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1
Ng, Kok Leong. "Kinetics and modelling of dimethyl ether synthesis from synthesis gas." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392222.
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Hagey, H. Louis. "Kinetic modelling of synthesis gas into hydrocarbons." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58214.pdf.
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Broberg, Marina. "FTIR method for analysis of synthesis gas." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-94539.
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The research institute ETC in Piteå is working with energy technical research and development. Today, much work revolves around research about renewable sources for fuel. In one project, biomass such as wood pellet is heated up while producing synthesis gas. The synthesis gas is then analyzed using three different GC techniques. ETC wanted to be able to make all their analysis on one instrument and with a faster speed. They contacted the company Rowaco in Linköping for help with developing a method on FTIR for analysis of the synthesis gas and that has been the aim for this thesis. A method has been developed for analysis of water, carbon monoxide, carbon dioxide and methane. The results from this thesis show that the concentrations of the molecules in the synthesis gas are outside the calibration curved that has been made and that the high concentrations give much interference to other molecules. The thesis also shows that many areas in the spectrum from the process are roof absorbers and there is also a contamination of water and carbon dioxide in the system. Suggested improvements are to find the source for the contamination, to develop calibration points with higher concentrations, to reduce the length of the gas cell and to dilute the gas before entering the FTIR.
4
Moore, Simon Andrew. "Formation of higher alcohols from synthesis gas." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272886.
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Dam, Bidhan Kumar. "Flashback propensity of gas mixtures." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Ardha, Vishwanath Reddy. "Laminar burning velocities of gas mixtures." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Pryce, Imogen Mary. "Calcium reclamation and synthesis of PCC for acid gas control in flue gas." Connect to resource, 2006. http://hdl.handle.net/1811/6477.
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Thesis (Honors)--Ohio State University, 2006.Title from first page of PDF file. Document formatted into pages: contains vi, 61 p.; also includes graphics. Includes bibliographical references (p. 59-60). Available online via Ohio State University's Knowledge Bank.
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Olsen, Susanne Kelly. "Catalytic membrane reactors for synthesis gas production from natural gas via partial oxidation." Thesis, Robert Gordon University, 2004. http://hdl.handle.net/10059/626.
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Natural gas obtained during the extraction of liquid hydrocarbons is often undesired due to the lack of infrastructure to transport the natural gas to an onshore location. As a result the natural gas is often flared causing economic waste and environmental concern. It would therefore be desirable to either convert the natural gas into some other substance which can be transported easily, or transport the natural gas in a liquid state. In that way, new field development will be more financially viable through the use of the extensive infrastructure and technology already in place in the offshore industry for transporting liquid hydrocarbons. It is considered that one feasible way of utilising offshore produced natural gas, is to convert it into synthetic gas (syngas) which can in turn be used to produce gases and fluids such as methanol, ammonia or a synthetic crude oil that can be readily pumped through the same pipelines as the produced oil. For the production of synthetic gas, membrane technology presents an attractive advantage improving conversion efficiency by operating as catalyst support, which then also increases the catalyst dispersion, resulting in optimal catalyst load and complete consumption of oxygen and methane in the partial oxidation. In the present investigation, an enhanced catalyst-dispersed ceramic membrane for low-cost synthesis gas production suitable for gas-to-liquids has been prepared, characterised and tested in a self-designed membrane reactor. The effect of temperature and feed flow rates has been studied and a kinetic model has been developed. In the novel membrane reactor, an active porous layer is located on both sides facing the oxygen and methane containing gas, adjacent is a second active porous layer and is supported by layers with increasing pore radii. Here the active porous layer on the bore side enhances the reaction between permeated oxygen and fuel species. In this study, it has also been demonstrated that the oxygen is activated prior to contacting the methane inside the membrane. This often results in 100% oxygen conversion, CO selectivity higher than 96% and syngas ratio (1-1/2 C O) of 2.2 to 1.8. Another advantage of the developed membrane system is that it can be used in high temperatures (> 1273.15K) and high pressure (80bars) processes with no variation on the flow rates, due to the mechanical strength of the ceramic support used.
9
Arinan, Ayca. "Direct Synthesis Of Dimethyl Ether (dme) From Synthesis Gas Using Novel Catalysts." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611490/index.pdf.
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Increasing prices of crude oil derived transportation fuels ascended the
researches on seeking alternative fuels, in last decades. Moreover, the increasing rate
of global warming, because of high greenhouse gas emissions initiated new research
for environment-friendly clean alternative fuels. Due to its low NOx emission, good
burning characteristics and high cetane number, dimethyl ether (DME) attracted
major attention as a transportation fuel alternative. Two possible pathways have been
proposed for DME production. One of these pathways is DME synthesis through
conventional methanol dehydration. More recently, direct DME synthesis in a single
step has attracted significant attention of researchers and fuel producers. Catalysts
having two active sites are required for direct DME synthesis from synthesis gas.
The aim of this work was to synthesize novel bifunctional direct DME
synthesis catalysts and test their activity in a high pressure fixed bed flow reactor.
Bifunctional mesoporous catalysts were synthesized by using one-pot hydrothermal
synthesis, impregnation and physical mixing methods. These materials were characterized by XRD, EDS, SEM, N2 physisorption and diffuse reflectance FT-IR
(DRIFTS) techniques.
Characterization results of the catalysts synthesized by one-pot hydrothermal
synthesis procedures in basic and acidic routes showed that pH value of the synthesis
solution was highly effective on the final physical structure and chemical nature of
the catalysts. Increase in the pH value promoted the incorporation of Cu, Zn and Al
into the mesoporous MCM-41 structure. Also, effects of Na2CO3 addition on the
catalyst structure during the hydrothermal synthesis procedure were investigated.
The characterization results showed that metals were incorporated into the catalyst
structure successfully. However, surface area results showed that loaded metals
blocked the pores of MCM-41 and decreased the surface area of the catalysts. Effects
of zirconium (Zr) metal with different weight ratios were also investigated. Results
showed that Zr loading increased the surface area of the catalyst.
A high pressure fixed bed flow reactor was built and the catalyst testing
experiments were performed between the temperature range of 200-400°C, at 50 bars. The activity results of the catalyst synthesized by impregnation method showed that no DME was formed over this catalyst
however it showed promising results for production of methanol and ethanol. Selectivity values of these alcohols were between 0.35 and 0.2. Formation of methane and CO2 indicated the occurrence of reverse dry reforming reaction. Incorporation of Zr into the catalyst structure at neutral synthesis condition caused significant activity enhancement, giving CO conversion values of about 40% at 400°
C. Product distribution obtained with this catalyst indicated the formation of DME, ethanol, methanol as well as CH4 and CO2. Highest DME selectivity (60%) was observed with the catalyst prepared by physical mixing of commercial methanol reforming catalyst with silicotungstic acid incorporated methanol dehydration catalyst having W/Si ratio of 0.4.
10
Rafiq, Muhammad Hamid. "Experimental Studies and Modeling of Synthesis Gas Production and Fischer-Tropsch Synthesis." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16572.
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Indirect route can be used to convert abundant natural resources such as natural gas (NG), coal and biomass to synthetic fuels (referred to as gas-to-liquid (GTL), coalto- liquid (CTL) and biomass-to-liquid (BTL)). It is currently one of the most effective solutions to the problem of finding suitable substitutes for liquid clean fuels. In this work, an investigation on the production of synthetic fuel from gaseous hydrocarbons (HCs)/bio-HCs and liquid bio-HCs on a small-scale unit has been carried out. The research project consists of two major parts, a modified version of a plasma-assisted catalytic partial oxidation (CPO) gliding arc (GlidArc) reactor and a thermally stable single-tube fixed-bed Fischer−Tropsch (FT) reactor. The potential for the CPO of methane to produce synthesis gas (syngas) was studied both experimentally and thermodynamically at a fixed pressure (1 bar) and electric power (0.3 kW). The investigations were performed in a partially adiabatic plasma-assisted (nonthermal) GlidArc reactor, using a Ni-based catalyst. Two cases were studied: in the first, normal air (molar ratio of O2/N2=21/79) was used, whereas enriched air (O2/N2=40/60) was utilized in the second. The individual effect of the O2/CH4 molar ratio, gas hour space velocity (GHSV) and bed exiting temperature (Texit) was studied for both cases. The main trends of the CH4 conversion, the syngas (H2 and CO) yield and the thermal efficiency of the reactor based on the lower heating value (LHV) were analyzed and compared. A numerical investigation of the CPO of methane to syngas using a GlidArc reactor was also studied. A 2D heterogeneous plug-flow model with radial dispersion and no gradients inside the catalyst pellet are used, including the transport equations for the gas and solid phase and reaction rate equations. The governing equations of this model formed a set of stationary differential algebraic equations coupled with the non-linear algebraic equations, and were solved numerically using in-house MATLAB code. Model results of CPO of methane were compared to previous experimental data with the GlidArc reactor found in the literature. A close match between the calculated and experimental results for temperature, reactant (CH4 and O2) conversion, H2 and CO yields and species molefraction were obtained. The developed model was extended to predict and quantify the influence of the GHSV as well as determine the influence of the reactor energy density (RED), the O2/CH4 molar ratio and the O2/N2 molar ratio. The predicted behaviors for the species mole-fraction, reactants conversion, H2 and CO yields and temperature along the length of the reactor have been analyzed. Furthermore, FT synthesis of a model biosyngas (33% H2, 17% CO and 50% N2) in a single tube fixed-bed FT reactor was investigated. The FT reactor consisted of a shell and tube with high-pressure boiling water circulating throughout the shell. A spherical unpromoted cobalt catalyst was used with the following reaction conditions: a wall temperature of 473 K, a pressure of 20 bars and a GHSV of 37 to 180 NmL/(gcat.h). The performance of the FT reactor was also validated by developing a 2D pseudo-homogeneous model that includes transport equations and reaction rate equations. Good agreement between the model predictions and experimental results were obtained. This developed model was extended to predict and quantify the influence of the FT kinetics as well as determine the influence of the tube diameter and the wall temperature. The predicted behaviors for CO and H2 conversion, productivity of HCs (mainly CH4 and C5 +) and fluid temperature along the axis of the reactor have been analyzed. In addition, the initial tests results are presented for the conversion of waste cookingoil (WCO) to biosyngas by CPO over a granular Ni-based catalyst. Additionally, autothermalreforming (ATR) of propane with water and normal air was also carried out.The investigations were performed in a partially adiabatic plasma-assisted (non-thermal)GlidArc reactor at fixed pressure (1 bar) and electric power (0.3 kW). Detailed axial temperaturedistributions, product concentrations, reactant conversions, H2 and CO yield,H2/CO ratio and thermal efficiency, as a function of the cold and hot WCO flow rate, thewater flow rate and the time on stream were studied. Propane and normal air were usedas oxidizing components to maintain autothermal operation. Finally, an investigation of the influence of process conditions on the production ofsyngas from model biogas (molar ratio of CH4/CO2=60/40) through partial oxidationover a granular Ni-based catalyst was explored. The investigations were performed in apartially adiabatic plasma-assisted (non-thermal) GlidArc reactor in a transitional flowregime at a fixed pressure (1 bar) and electric power (0.3 kW). The emphasis of this investigationwas on an experimental study and a comparative thermodynamic analysis. Theequilibrium compositions were calculated using a Lagrange multiplier and resulted in thedevelopment of systems of non-linear algebraic equations, which were solved numericallyusing the MATLAB function “fmincon”. Two cases were studied: normal air (molar ratioof O2/N2=21/79) and enriched air (O2/N2=40/60). The individual effects of the O2/CH4molar ratio and the Texit were studied in both cases. The main trends of the CH4 conversion,the syngas yield, the H2/CO ratio and the thermal efficiency of the reactor wereanalyzed.
11
Van, Lier Erik. "Gas phase methanol synthesis for carbon-11 radiopharmaceuticals." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/32488.
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Carbon-11 radiopharmaceuticals are gaining an increasing importance in positron emission
tomography due to their importance in diagnostic medicine. The most wide spread method
of production of these radiopharmaceuticals is by methylation of an appropriate precursor
with the highly reactive [¹¹C]methyl iodide. Conventional synthesis of this intermediate
involves liquid phase synthesis of [¹¹C]methanol, which is the step that limits the specific
activity of the final product. A catalytic gas phase methanol synthesis process was evaluated,
that promises to avoid the loss of specific activity. In this procedure, [¹¹C]carbon
dioxide produced in the target is first trapped and purified, then converted to [¹¹C]carbon
monoxide using molybdenum and finally reduced to [¹¹C] methanol using a copper zinc
oxide catalyst in the presence of hydrogen.
In this study a device to trap and purify [¹¹C]carbon dioxide was developed and optimized.
[¹¹C] Carbon dioxide produced in target was quantitatively trapped at -20° C on a
carbon molecular sieve column and quantitatively released in less than 3.5 minutes.
A reactor to convert 50 ppm carbon dioxide to carbon monoxide, based on the reaction
with molybdenum, was developed. A commercially available process simulator was used
to assist the optimization of operating conditions and molybdenum pretreatment methods.
Under optimal conditions, carbon dioxide was converted to carbon monoxide with over
70% yield.
A reactor to catalytically convert 50 ppm carbon monoxide to methanol was developed.
A copper zinc oxide catalyst was prepared by a co-precipitation method. The catalyst was
activated by reduction with hydrogen and passivated with compressed air prior to methanol
synthesis. The effect of temperature, pressure and flowrate on the conversion of carbon
monoxide to methanol were studied and results were used to create a kinetic model. This
model was used to determine optimal operating conditions for this reactor and predicts 60%
conversion of [¹¹C]carbon monoxide to [¹¹C]methanol.
These findings suggest that gas phase [¹¹C] methanol synthesis is a viable alternative to
the conventional liquid phase method, meriting further studies with carbon-11.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
12
Richards, D. G. "Synthesis gas conversion to oxygenates using rhodium catalysts." Thesis, Brunel University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381157.
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Dasgupta, Debalina. "ENHANCING GAS PHASE FISCHER-TROPSCH SYNTHESIS CATALYST DESIGN." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1674093841&sid=6&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2008."College of Engineering." Keywords: Bimetallic, Catalysts, Iron-cobalt, Fischer-Tropsch synthesis, Ruthenium Includes bibliographical references (p. 123-134). Also available online.
14
Davis, Geoffrey P. "Transparent polyurethanes : synthesis, characterisation and mustard gas resistance." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/11238.
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Transparent Polyurethanes based upon Polycaprolactone and H 12MDIisocyanate (Desmodur W) have been synthesised and tested with regard to permeation by Mustard Gas (HD). Variations in soft segment molecular weight, reaction ratio, and chain extender, as well as the effect of crosslinking have been investigated. It was found that the principal factor governing permeation behaviour was soft segment molecular weight. However as hard segment content increased the determinant role of the soft segment diminished. Morphological Analysis of the synthesised polyurethanes was carried out using DSC, CMI'A, GPC, and WAXD techniques. The physical properties (Hardness, Tensile Strength, etc) of these materials were also determined. Results showed that the use of mixed diol chain extenders or trifunctional crosslinking elements produced increased phase mixing in the polyurethanes as a consequence of poorer hard segment domain organisation. This had the effect of reducing soft segment restrictions such that poorer permeation performance was obtained. GPC and DSC Analysis of the various polycaprolactones used in the synthesis programme suggested that the lower molecular weight polyols (550-2000) were composed of at least two different molecular weight species. Work with mixed polyol formulations indicated this may affect the physical properties of the polyurethanes. GPC Analysis of the synthesised polyurethanes themselves showed a wide variety of molecular weights were obtained; these were seen to be very dependent upon polyol molecular weight. The CAPA 210 (1000 Mol.Wt.) based elastorners had the highest Mn values. It is believed these variations in molecular weight are related to the presence of different catalysts, activators, etc in the original polyols. Injection Moulding trials were carried out on the formulation considered to be the most promising candidate for the face mask material. Slight changes in physical properties were obtained as processing conditions were varied. Most significantly the polyurethane began to shown signs of yellowing at high injection temperatures (190°C and above).
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Yin, Xiuli. "Synthesizing methanol from biomass derived syngas." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31456844.
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Campbell, Kay Ann. "Synthesis and reactions of strained bicyclic enones." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/27697.
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Osgood, Eric S. "Transient gas chromatograph analysis of biomass synthesis gas produced in a lab scale gasifier." Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2600.
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Md, Saad Juniza. "Dry reforming of waste plastics for synthesis gas production." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15698/.
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Thermal processing is an effective technique for recycling waste plastics in a sustainable way. The pyrolysis of waste plastics, followed by reforming reactions of the pyrolysis products generates syngas (hydrogen and carbon monoxide) that has a vast array of applications. To date, the steam reforming process has been the most researched technology for syngas production from waste plastics. However, this process produces a large amount of carbon dioxide. Due to the concern related to global warming associated with the emissions of carbon dioxide into the atmosphere, the recycling of carbon dioxide through the pyrolysis-reforming of waste plastic, (dry reforming) is environmentally attractive. The dry reforming process was the focus of this research. A preliminary thermogravimetric and kinetic analysis was conducted in order to have a general understanding on the effect of CO2 in a waste plastics pyrolysis. The results show that most plastics required lower activation energy with the presence of CO2 in the pyrolysis atmosphere (N2:CO2 ratio of 7:3). A two-stage pyrolysis-catalytic dry reforming reactor was used to investigate various process conditions and types of catalyst to maximise syngas production. The two-stage fixed bed reaction systems increased the H2 in both a N2 or CO2 atmosphere. Ni/Al2O3 based catalysts with different metal promoters (Mg, Cu and Co) were selected for the investigation of pyrolysis-dry reforming of waste plastics. Among the catalysts tested, the Ni-Co/Al2O3 catalyst presented the highest catalyst activity resulting in a syngas production of 149.42 mmolsygas g-1plastic with 58% carbon dioxide conversion, also no detectable carbon formation on the catalyst surface was observed. The dry reforming reaction was also favoured with the Ni-Co/Al2O3 catalyst with high cobalt content. Various process parameters such as catalyst preparation method, reforming temperature, CO2 feed input rate and catalyst to plastic ratio were tested. It was found that the addition of steam in the catalytic-dry reforming process manipulated the H2/CO molar ratio, based on the type of catalyst used and the CO2/steam feed ratio. Better catalyst activity in relation to H2 production was observed for the Ni-Mg/Al2O3 catalyst and Ni-Co/Al2O3 catalyst favoured CO production. Different types of plastics; individual and mixed plastics from different waste treatment plants were also processed through the catalytic-dry reforming process to determine the syngas production and catalyst activity of Ni-Co/Al2O3 catalyst. This research has suggested that the use of carbon dioxide as the reforming agent in the dry reforming process of waste plastics was comparable to the current reforming technology with an optimum syngas production of 148.6 mmol g-1SWP.
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Morrison, Christine Evon. "PRODUCTION OF ETHANOL FROM THE FERMENTATION OF SYNTHESIS GAS." MSSTATE, 2004. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07022004-175606/.
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Ethanol produced from lignocellulosic agricultural products and waste is an environmentally-friendly alternative to petroleum-derived fuel. Lignocellulosic biomass is gasified producing synthesis gas, which is composed of CO, CO2, and H2. Synthesis gas is fermented via anaerobic biocatalyst. The bacterium was grown in a fructose-rich medium then concentrated in ethanol production medium for synthesis gas fermentation. While the known ethanol-producing bacterium Clostridium ljungdahlii was used to provide baseline values for synthesis gas utilization and ethanol production, synthesis gas fermentation were conduced with a culture discovered at Mississippi State University. Additionally, efforts were made to isolate other anaerobic cultures capable of fermenting synthesis gas to ethanol.
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Martin, Margarita. "Synthesis of heat integrated gas separation systems incorporating absorption." Thesis, University of Manchester, 2009. http://www.manchester.ac.uk/escholar/uk-ac-man-scw:228857.
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There is an economic incentive to substitute energy and capital-intensive conventional gas separation schemes based on cryogenic distillation. Absorption has potential advantages over low-temperature schemes as it does not rely on high refrigeration requirements to perform the separation. An optimisation-based synthesis framework has been developed that integrates distillation and absorption-desorption schemes. This methodology is able to quantitatively resolve the numerous tradeoffs between the various capital and operating factors and systematically suggest new design configurations. A multilevel modelling approach enables the accommodation of absorption-desorption separation options in the distillation orientated framework supported by COLOM® (©Centre for Process Integration, University of Manchester). Improved shortcut models for reboiled absorption and distillation columns have been proposed, which are suitable for exploitation in the developed synthesis framework. A new methodology for heat integration is proposed that achieves efficient heat recovery and proposes a configuration of the heat exchanger network. This methodology works in harmony with the optimisation framework. Simultaneous optimisation of the separation system, the heat exchanger network and the refrigeration system offers the opportunity of achieving a superior overall configuration. The structural and operating variables of the separation system are optimised by Simulated Annealing. As a stochastic optimisation method, SA can deal with the large scale of the problem and its discontinuous and non-linear nature imposed by the feasibility limits of the separations and the model equations. The optimal separation configurations are selected on the grounds of minimum capital and operating costs. An analysis of costing methods is provided which aims at rationalising the basis for cost estimation. The application of the developed synthesis methodology is illustrated by a number of examples of relevance to the natural gas processing and refinery gas processing. Results will emphasise the functionality of the methodology as a tool for quantitative evaluation of preliminary designs and realisation of highly integrated and efficient process concepts.
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Muiruri, Mburu. "Synthesis and operation of zeolite membranes for gas separation." Thesis, University of Bath, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285288.
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Bourne, Samuel. "Development of novel gas-flow methodologies for pharmaceutical synthesis." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708895.
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Wang, Jiaona. "Synthesis and optimisation of low temperature gas separation processes." Thesis, University of Manchester, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488066.
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This thesis includes two sections. The first section presents a new synthesis framework for screening low temperature heat integrated separation systems. The synthesis and optimisation of low temperature gas separation processes is complex due to the large number of design options for both the separation system and the refrigeration system. In this thesis, task representation is applied to the separation system to accommodate both simple and complex distillation columns. Each task has been developed with several device representations. Condensation for separation is provided by the refrigeration system or heat integration. Design issues for the refrigeration system address the choice of refrigerant, selection of refrigeration structure and heat integration between the refrigeration system with separation processes and within separation process. A sequence-based superstructure is presented to accommodate all options in separation processes. The optimisation framework starts from the investigation of all the task representations for the separation system. Short-cut models of all the novel separation options are provided. An integration procedure is presented based on shaft power targeting. The large number of design options makes conventional enumerative or MiLP methods impractical. Also, for the MINLP, it is difficult to reach the actual optimum due to the highly non-linear nature of the models. In this thesis, the optimisation is carried out using a stochastic method (Genetic Algorithm) which can efficiently tackle mixed variables. Various case studies are examined for various design scenarios. Dephlegmation is an effective low temperature gas separation process, which has been used to reduce power consumption and improve separation efficiency. However, most existing models of a dephlegmator have focused on separation process simulation, the heat exchange characteristics and the refrigeration design were either ignored or based on highly simplified assumptions. The second section of this thesis presents a new framework for the design of dephlegmators that addresses simulation of the multi-component partial condensation, selection of plate-fin heat exchangers and design of the refrigeration process. For simulation, a film model is applied to estimate local mass and heat transfer and integrate for the total area separation. In the design of plate-fin heat exchangers, the key issue is to determine the controlling stream according to the flow pattern in the separation passages Design of refrigeration focuses on the optimisation of the composition when mixed refrigerants are used and on partition temperature when cascade cycles are used. A systematic methodology is proposed to include all these aspects. Various cases are used to provide guidelines in the design of dephlegmators used in multi-component gas mixtures with different refrigeration systems.
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Gumus, Rhoda Habor. "Synthesis gas production from biogas using Ni-based catalyst." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/33769.
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As a result of global climate changes brought about by human activity, more sustainable sources of energy are being sought as alternatives to fossil fuels. Biomass is of particular interest as a sustainable source of energy since it does not contribute to net CO2 emissions. Reforming of methane derived from biomass with CO2 may form the basis of an efficient means to produce synthesis gas which has many applications m the petrochemical and allied industries. The objective of this study was the investigation of CO2 reforming of methane (simulating biogas) over effective supported nickel catalysts capable of long term operation without significant loss of activity and stability.
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Taconi, Katherine Ann. "Methanogenic generation of biogas from synthesis-gas fermentation wastewaters." Diss., Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-07072004-085409.
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Sakaguchi, Toshikazu. "Synthesis, properties, and gas permeability of novel poly(diarylacetylenes)." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/143983.
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Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第12286号
工博第2615号
新制||工||1369(附属図書館)
24122
UT51-2006-J279
京都大学大学院工学研究科高分子化学専攻
(主査)教授 増田 俊夫, 教授 中條 善樹, 教授 伊藤 紳三郎
学位規則第4条第1項該当
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FLORES, JHONNY OSWALDO HUERTAS. "DIRECT SYNTHESIS OF HYDROCARBONS FROM SYNTHESIS GAS OVER HYBRID CATALYSTS BASED ON HFERRIERITE ZEOLITE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=12467@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Existe uma crise energética devido ao excessivo consumo do petróleo e à contaminação em suas diversas formas. Há enormes reservas de gás natural e a conversão deste gás em combustíveis líquidos a partir do gás de síntese, que vem do gás natural, via metanol, e posterior transformação do metanol em hidrocarbonetos é uma interessante alternativa. Catalisadores híbridos formados por um catalisador de síntese de metanol e um material ácido poroso, geralmente uma zeólita, são empregados para esta síntese direta. Seis famílias de catalisadores híbridos foram sintetizadas onde diversas variáveis foram testadas como: método de preparação do catalisador híbrido, método de preparação do catalisador de síntese de metanol, fase ativa, razão catalisador de síntese de metanol/zeólita, acidez da zeólita e diferente promotor. A zeólita empregada em todos os sistemas foi a H-ferrierita. O método de preparação influenciou nas propriedades estruturais, texturais, morfológicas, ácidas e catalíticas do catalisador híbrido. O melhor método de preparação do catalisador híbrido foi o método de coprecipitação-sedimentação que se mostrou mais ativo em temperaturas acima de 300°C. Observaram-se diferenças morfológicas nas partículas do catalisador de síntese de metanol (CSM) quando diferentes métodos de preparação foram empregados. O cobre, entre as fases ativas, mostrou-se a melhor na síntese direta de hidrocarbonetos a partir do gás de síntese em temperaturas acima de 300°C. A melhor razão catalisador de síntese de metanol/zeólita, nesta síntese direta, foi de 2:1. O cromo no sistema Cu-Zn-Al favoreceu a atividade em 250°C. Baixas razões acidez total/área de Cu(0) e altas temperaturas (350 e 400°C) favoreceram maiores conversões e seletividades em propano e butano, baixas temperaturas (300°C) favoreceram a formação de DME. Altas razões acidez total/área de Cu(0) favoreceram a formação de etano. A distribuição dos produtos na síntese direta de hidrocarbonetos a partir do gás de síntese foi dependente da temperatura de reação. Éter dimetílico apresentou um máximo em 300ºC. A síntese do metanol, parece ser a etapa limitante do processo.
An energy crisis due to the extreme consumption of the oil and to the contamination in its diverse forms exists. There are enormous natural gas reserves and the conversion of this gas in liquid fuels from the synthesis gas, through methanol, and posterior transformation of methanol in hydrocarbons is an interesting alternative. Hybrid catalysts based in methanol synthesis catalyst and an acidic porous material such as zeolites, are used for this direct synthesis. Six groups of hybrid catalyst were prepared and several properties studied such: preparation method of the hybrid catalyst, preparation method of the methanol synthesis catalyst, active site, CuO-ZnO-Al(2)O(3)/H- ferrierite ratio, acidity of the zeolite and different promoter. The zeolite used in all the systems was the ferrierite. The preparation method influenced the structural, textural, morphologic, acid and catalytic properties of the hybrid catalyst. The coprecipitationsedimentation method was more active in temperatures above 300°C. Morphologic differences in particles of the catalyst of methanol synthesis were observed when different preparation methods were used. The copper as active site was the better in the direct synthesis of hydrocarbons from synthesis gas in temperatures above 300°C. The best CuO-ZnO-Al(2)O(3)/H- ferrierite catalyst ratio, in this direct synthesis, was 2:1. The chromium in the Cu-Zn- Al system favored the activity in 250°C. Low acidity/metallic area Cu(0) ratio and high temperatures (350 and 400°C) favored higher activities and selectivities in propane and butane, lower temperatures (300°C) favored the DME formation. High acidity/metallic area Cu(0) ratio favored the formation of ethane. The hydrocarbons distribution was dependent on the reaction temperature. Dimethyl ether showed a maximum at 300°C. The methanol, seens to be the limitant step of the process.
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Yin, Xiuli, and 陰秀麗. "Synthesizing methanol from biomass derived syngas." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31456844.
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Young, Kay. "Mixed metal alkoxides as catalyst precursors." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6528/.
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This thesis describes research carried out to explore the use of mixed metal alkoxides as precursors of materials with catalytic activity in synthesis-gas chemistry. The alkoxide derived catalyst materials are compared against catalysts prepared by traditional co-precipitation methods. A discussion of the project objectives introduces the work and Chapter 1 includes a chronological survey of the literature up to the present day. A brief discussion of the commercial uses of alkoxides is given. Chapter 2 describes the general methods of synthesis and the properties of simple and bimetallic alkoxides; M(OR)(_x) and M[M'(OR)(_n)](_x) respectively. A more detailed treatment of the alkoxides of the first row transition elements is given, with emphasis on the properties and characteristics responsible for their possible potential as catalyst precursors. Chapter 3 deals with the catalytic aspects of ammonia and methanol synthesis. The preparation of industrial, heterogeneous catalysts has traditionally been carried out by co-precipitation of, for example, basic carbonates. The catalytic materials obtained may display catalytic activities which vary markedly (and not always controllably) with the precipitation, ageing, calcinations and/or reduction conditions employed. A discussion of the reaction mechanisms involved in ammonia and methanol syntheses is included. Several mixed metal alkoxides have been prepared from metals known to have catalytic activity in synthesis-gas chemistry (i.e. Mn, Fe, Co, Cu, Zn and Al). These metal alkoxides (e.g. Cu[Al(OPr(^1) (_4)](_2) ) have been characterised and found to compare well with literature data. Analyses, Infra-red and Mass-spectra are reported. After conversion to catalytic materials the alkoxide derived compounds were examined for surface properties ( oxide phases present, copper surface area, crystallite size, pore size distributions and pore volumes). The alkoxide materials compared quite well with the precipitated analogues and there was a difference in the properties of materials derived from different alkoxy groups. These studies were limited to the copper-aluminium alkoxides. The formation of a nickel (II) chloride, HMPA adduct is reported.
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Hayes, Martin John. "An investigation of Câ†2-oxygenate direct synthesis from CO/Hâ†2 mixtures over oxide-supported rhodium catalysts." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262274.
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Doan, Phuong Thanh. "Characterization of Cu-Co-Cr-K catalysts." Master's thesis, Mississippi State : Mississippi State University, 2001. http://library.msstate.edu/etd/show.asp?etd=etd-07022001-195724.
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Niemelä, Marita. "Reactions of synthesis gas on silica supported transition metal catalysts /." Espoo : Technical Research Centre of Finland, 1997. http://www.vtt.fi/inf/pdf/publications/1997/P310.pdf.
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Cotter, Jacqueline Louise. "Ethanol and Acetate Production from Synthesis Gas using Microbial Catalysts." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-08142006-111149/.
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The feasibility of inducing a resting stage in cultures of Clostridium ljungdahlii and Clostridium autoethanogenum was evaluated. Additionally, the effects of medium pH and benzyl viologen, a electron mediator, were tested separately for resting C. ljungdahlii cultures. Cells were grown on nitrogen-rich basal media, a modified Reinforced Clostridial Media and DSMZ 640 for C. ljungdahlii and C. autoethanogenum respectively, and then transferred to nitrogen-limited media to induce the resting stage. The performance of the resting cultures was evaluated by product formation (ethanol and acetate), culture stability, and cell viability. It was found that C. ljungdahlii was able to be induced into a stable non-growing stage with basal medium supplemented with vitamins and trace elements and devoid of the major nitrogen sources: yeast extract, beef extract, and proteose peptone, RCM.NA.SVE. However, there was no significant product formation in the resting cultures of C. ljungdahlii. Three pH levels, 6.8 (the control), 5.5, and 4.5, were tested for affects on C. ljungdahlii resting cell performance. The medium pH of resting cultures in NG.RCM.NA.SVE did not improve product formation of non-growing C. ljungdahlii cultures. The more acidic pH of the non-growing media reduced the culture viability from 100 % at pH 6.8 to 44.4 and 11.1 % at pH 5.5 and 4.5 respectively. Three levels of benzyl viologen concentration were tested for affects on C. ljungdahlii resting cell performance: 0, 50, and 100 part per million. The addition of benzyl viologen did not enhance the cultures? product formation capabilities. The benzyl viologen in the resting cell media also negatively affected the culture viability leaving only 33.3 and 55.5 % of the cultures viable with 100 and 50 ppm benzyl viologen respectively. C. autoethanogenum cultures were not able to be induced into stable non-growing cultures. With various nitrogen-source limitations from the basal medium cultures experienced either significant increases or decreases in culture density over time. The ethanol product selectivity in both non-growing and growing cultures of C. autoethanogenum in nitrogen-limited media was improved from the growing C. autoethanogenum in the basal medium. The ethanol to acetate production ratio was improved to 1:4.5 in two different nitrogen-limited media (one without yeast extract or trypticase peptone in which the culture density decreased, and only devoid of yeast extract in which the culture grew) from 1:7 in the basal growth medium. All cultures of C. autoethanogenum remained viable after transfer from the growth media to the non-growth media. From these studies it appears that ethanol is a primary metabolite for both C. ljungdahlii and C. autoethanogenum on sugar substrates.
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Borgonovo, Cecilia. "Synthesis of Aluminum-Aluminum Nitride Nanocomposites by Gas-Liquid Reactions." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-dissertations/224.
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An innovative method has been developed for synthesizing aluminum-aluminum nitride nanocomposite materials wherein the reinforcing nano-sized aluminum nitride particles are formed in-situ in a molten aluminum alloy. This method, which circumvents most issues associated with the traditional ways of making nanocomposites, involves reacting a nitrogen-bearing gas with a specially designed molten aluminum alloy. The method ensures excellent dispersion of the nanoparticles in the matrix alloy, which is reflected in enhanced mechanical properties. In this thesis, the author reviews the limitations of the conventional methods of manufacturing nanocomposites and develops thermodynamic and kinetic models that allow optimizing the in-situ gas-liquid process to produce quality nanocomposite material. Also, in this thesis, the author reports the measured room temperature and elevated temperature tensile properties of materials that were made by the optimized process and compares the measured values to their counterparts obtained for the base alloy. A 75 pct. increase in room temperature yield strength is obtained when the base alloy is reinforced with one pct. nano-size aluminum nitride particles and this significant increase in yield strength is accompanied by only negligible loss of ductility.
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Shirridan, Caroline. "The catalytic decomposition of ethanol to a synthesis gas mixture." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/11913.
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Suárez, París Rodrigo. "Catalytic conversion of biomass-derived synthesis gas to liquid fuels." Doctoral thesis, KTH, Kemisk teknologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-182690.
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Climate change is one of the biggest global threats of the 21st century. Fossil fuels constitute by far the most important energy source for transportation and the different governments are starting to take action to promote the use of cleaner fuels. Biomass-derived fuels are a promising alternative for diversifying fuel sources, reducing fossil fuel dependency and abating greenhouse gas emissions. The research interest has quickly shifted from first-generation biofuels, obtained from food commodities, to second-generation biofuels, produced from non-food resources. The subject of this PhD thesis is the production of second-generation biofuels via thermochemical conversion: biomass is first gasified to synthesis gas, a mixture of mainly H2 and CO; synthesis gas can then be catalytically converted to different fuels. This work summarizes six publications, which are focused on the synthesis gas conversion step. Two processes are principally examined in this summary. The first part of the PhD thesis is devoted to the synthesis of ethanol and higher alcohols, which can be used as fuel or fuel additives. The microemulsion technique is applied in the synthesis of molybdenum-based catalysts, achieving a yield enhancement. Methanol cofeeding is also studied as a way of boosting the production of longer alcohols, but a negative effect is obtained: the main outcome of methanol addition is an increase in methane production. The second part of the PhD thesis addresses wax hydroconversion, an essential upgrading step in the production of middle-distillate fuels via Fischer-Tropsch. Bifunctional catalysts consisting of noble metals supported on silica-alumina are considered. The deactivation of a platinum-based catalyst is investigated, sintering and coking being the main causes of decay. A comparison of platinum and palladium as catalyst metal function is also carried out, obtaining a fairly different catalytic performance of the materials in terms of conversion and selectivity, very likely due to dissimilar hydrogenation power of the metals. Finally, a kinetic model based on the Langmuir-Hinshelwood-Hougen-Watson formalism is proposed to describe the hydroconversion reactions, attaining a good fitting of the experimental data.Klimatförändringarna är ett av de största globala hoten under det tjugoförsta århundradet. Fossila bränslen utgör den helt dominerande energikällan för transporter och många länder börjar stödja användning av renare bränslen. Bränslen baserade på biomassa är ett lovande alternativ för att diversifiera råvarorna, reducera beroendet av fossila råvaror och undvika växthusgaser. Forskningsintresset har snabbt skiftat från första generationens biobränslen som erhölls från mat-råvaror till andra generationens biobränslen producerade från icke ätbara-råvaror. Ämnet för denna doktorsavhandling är produktion av andra generationens biobränslen via termokemisk omvandling. Biomassa förgasas först till syntesgas, en blandning av i huvudsak vätgas och kolmoxid; syntesgasen kan sedan katalytiskt omvandlas till olika bränslen. Detta arbete sammanfattar sex publikationer som fokuserar på steget för syntesgasomvandling. Två processer är i huvudsak undersökta i denna sammanfattning. Den första delen av doktorsavhandlingen ägnas åt syntes av etanol och högre alkoholer som kan användas som bränsle eller bränsletillsatser. Mikroemulsionstekniken har använts vid framställningen av molybden-baserade katalysatorer, vilket gav en höjning av utbytet. Tillsatsen av metanol har också studerats som ett sätt att försöka få en högre koncentration av högre alkoholer, men en negativ effekt erhölls: huvudeffekten av metanoltillsatsen är en ökad metanproduktion. Den andra delen av doktorsavhandlingen handlar om vätebehandling av vaxer som ett viktigt upparbetningssteg vid framställning av mellandestillat från Fischer-Tropsch processen. Bifunktionella katalysatorer som består av ädelmetaller deponerade på silica-alumina valdes. Deaktiveringen av en platinabaserad katalysator undersöktes. Sintring och koksning var huvudorsakerna till deaktiveringen. En jämförelse mellan platina och palladium som funktionella metaller genomfördes också med resultatet att det var en ganska stor skillnad mellan materialens katalytiska egenskaper vilket gav olika omsättning och selektivitet, mycket sannolikt beroende på olika reaktionsmönster hos metallerna vid vätebehandling. Slutligen föreslås en kinetisk modell baserad på en Langmuir-Hinshelwood-Hougen-Watson modell för att beskriva reaktionerna vid vätebehandling. Denna modell ger en god anpassning till experimentella data.
El cambio climático es una de las mayores amenazas del siglo XXI. Los combustibles fósiles constituyen actualmente la fuente de energía más importante para el transporte, por lo que los diferentes gobiernos están empezando a tomar medidas para promover el uso de combustibles más limpios. Los combustibles derivados de biomasa son una alternativa prometedora para diversificar las fuentes de energía, reducir la dependencia de los combustibles fósiles y disminuir las emisiones de efecto invernadero. Los esfuerzos de los investigadores se han dirigido en los últimos años a los biocombustibles de segunda generación, producidos a partir de recursos no alimenticios. El tema de esta tesis de doctorado es la producción de biocombustibles de segunda generación mediante conversión termoquímica: en primer lugar, la biomasa se gasifica y convierte en gas de síntesis, una mezcla formada mayoritariamente por hidrógeno y monóxido de carbono; a continuación, el gas de síntesis puede transformarse en diversos biocombustibles. Este trabajo resume seis publicaciones, centradas en la etapa de conversión del gas de síntesis. Dos procesos se estudian con mayor detalle. En la primera parte de la tesis se investiga la producción de etanol y alcoholes largos, que pueden ser usados como combustible o como aditivos para combustible. La técnica de microemulsión se aplica en la síntesis de catalizadores basados en molibdeno, consiguiendo un incremento del rendimiento. Además, se introduce metanol en el sistema de reacción para intentar aumentar la producción de alcoholes más largos, pero los efectos obtenidos son negativos: la principal consecuencia es el incremento de la producción de metano. La segunda parte de la tesis estudia la hidroconversión de cera, una etapa esencial en la producción de destilados medios mediante Fischer-Tropsch. Los catalizadores estudiados son bifuncionales y consisten en metales nobles soportados en sílice-alúmina. La desactivación de un catalizador de platino se investiga, siendo la sinterización y la coquización las principales causas del problema. El uso de platino y paladio como componente metálico se compara, obteniendo resultados catalíticos bastante diferentes, tanto en conversión como en selectividad, probablemente debido a su diferente capacidad de hidrogenación. Finalmente, se propone un modelo cinético, basado en el formalismo de Langmuir-Hinshelwood-Hougen-Watson, que consigue un ajuste satisfactorio de los datos experimentales.
QC 20160308
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KHAN, Fareha Zafar. "Synthesis, Characterization, and Gas Permeation Properties of Novel Cellulose Derivatives." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/57276.
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Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第13842号
工博第2946号
新制||工||1435(附属図書館)
26058
UT51-2008-C758
京都大学大学院工学研究科高分子化学専攻
(主査)教授 増田 俊夫, 教授 中條 善樹, 教授 木村 俊作
学位規則第4条第1項該当
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Azenha, Ivo Samuel Caniceiro. "Synthesis, characterization and modeling of zeolitic membranes for gas separation." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15272.
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Mestrado em Engenharia QuímicaThe interest on inorganic membranes has been growing significantly due to their remarkable properties like mechanical, thermal and chemical stabilities, and the ability to perform selective separations based on the kinetic diameter and surface affinity, acting as molecular sieves. The main objectives of this work were: (i) the application of the Maxwell-Stefan (MS) formalism to gas permeation through zeolite-type membranes in order to explore its potential as purely predictive tool; (ii) the development of new MS thermodynamic factors for the Dubinin-Astakhov and Dubinin-Radushkevich isotherms, since they are fundamental in the field of microporous materials; (iii) modeling water permeation through zeolites 13X and 4A membranes after accurate analysis of the influence of isotherm data and effective diffusivity upon permeation; (iv) synthesis and characterization of AM-3 (Aveiro Manchester number 3) titanosilicate membranes for gas separation. Regarding membranes preparation, they were synthesized hydrothermally up to three consecutive times on tubular α-alumina supports through a secondary growth technique. Through X-ray diffraction and scanning electron microscopy it was possible to conclude that after three depositions the AM-3 becomes clearly evident. The influence of pH was also studied and it was verified that a pure phase of AM-3 was not obtained. The dynamic characterization of the membrane disclosed the existence of macro and/or meso-defects, since helium permeances decreased with increasing temperature. The consecutive heating and cooling cycles were able to enhance gas permeance values. Concerning modeling, the MS thermodynamic factors of Dubinin-Astakhov and Dubinin-Radushkevich isotherms were derived for the first time. These factors were successfully validated using published data for methane and ethane on a silicalite-1 membrane. The results showed they are simultaneously able to correlate pure gas permeation and are capable of predicting binary mixture separation, which is a much more important achievement in this field. It was also disclosed that the methane and ethane diffusivities are essentially independent of the fractional occupancy. The water permeation through zeolites 13X and 4A membranes was predicted using MS approach. The influence of temperature and solid loading upon the effective diffusivities was previously modeled, being possible to observe very distinct and non-linear behaviors for both materials. The results evidenced higher fluxes for zeolite 13X, due to its higher pore size. Moreover the flux decreases with increasing temperature, being the opposite verified for the zeolite 4A membrane.
O interesse por membranas inorgânicas tem crescido significativamente devido a propriedades notáveis como a elevada estabilidade mecânica, térmica e química, e a capacidade de efetuarem separações seletivas assentes na afinidade e diâmetro moleculares, atuando como peneiros moleculares. Os objetivos principais deste trabalho foram: (i) a aplicação do formalismo de Maxwell-Stefan (MS) à permeação de gases em membranas zeolíticas de forma a explorar o seu potencial puramente preditivo; (ii) o desenvolvimento de novos fatores termodinâmicos de MS para as isotérmicas de Dubinin-Astakhov e Dubinin-Radushkevich; (iii) a modelação da permeação de água em membranas zeolíticas 13X e 4A, precedida de um estudo rigoroso da influência dos dados de equilíbrio e das difusividades efetivas sobre os resultados; (iv) síntese e caracterização de membranas de titanossilicato AM-3 (Aveiro-Manchester número três) para separação de gases. No que respeita à preparação das membranas de AM-3, estas foram sintetizadas hidrotermicamente em suportes tubulares de α-alumina pelo método de crescimento secundário. Observou-se a formação do filme de AM-3 por difração de raios X e microscopia eletrónica de varrimento. Efetuou-se ainda um estudo de pH tendo-se observado que na gama de concentrações em causa não se conseguiu obter uma fase pura de AM-3. A caracterização dinâmica da membrana de AM-3 mostrou a existência de macro e/ou meso defeitos devido à permeância (do hélio) diminuir com o aumento da temperatura. A realização de ciclos consecutivos de aquecimento e arrefecimento permitiu aumentar os valores de permeância. Relativamente à modelação foram derivados pela primeira vez os fatores termodinâmicos de MS para as isotérmicas de Dubinin-Astakhov e Dubinin-Radushkevich. Estes foram validados com sucesso, usando dados de metano e etano em membrana de silicalite-1. Os resultados mostraram que estes fatores são simultaneamente capazes de correlacionar a permeação de gases puros e prever, a partir deles, a separação de misturas binárias, o que é um feito notável nesta área de investigação. As difusividades do metano e etano são essencialmente independentes da concentração no sólido. A permeação de água através de membranas de zeólitos 13X e 4A foi prevista usando a abordagem de MS. A influência da temperatura e da carga do sólido sobre as difusividades efetivas foi previamente modelada, tendo-se observado comportamentos muito distintos e não lineares nos dois materiais. Os resultados evidenciaram fluxos mais elevados para o zeólito 13X (devido ao maior tamanho de poro), que diminuem com o aumento da temperatura. No caso do zeólito 4A o comportamento foi o oposto.
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Reiss, Paul. "Porous organic cages : synthesis and application in noble gas separation." Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/2032459/.
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Porous organic cages have recently received much attention due to their synthetic tunability, solution processability, high gas adsorption capacities, and ability to selectively separate small molecules based on their size and shape. In this thesis, a range of novel porous organic cages are presented, with each possessing unique functionalities, pore structures and gas sorption properties due to the employment of synthetically-modified versions of traditional trialdehyde and diamine cage precursors. The introduction of new functionality into the cage structure, including methyl, hydroxyl and ethanoanthracene groups, highlights how subtle modification of the cage precursors can initiate significant changes in the self-assembly of the cage molecules. This in turn affects the pore dimensions, as well as the gas sorption and separation performance, of the resultant porous material. This strategy led to the successful isolation of an asymmetric cage molecule, which demonstrated the potential to separate noble gases, as well as the preparation of cages with diverse vertex functionality, molecular size and gas sorption properties. The ability of porous organic cages to selectively separate xenon from krypton gas was also investigated through the use of dynamic breakthrough measurements, with the performance of these cages surpassing all other porous materials evaluated to date.
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Hunt, Joseph Ray. "Synthesis, characterization, and gas adsorption properties of covalent organic frameworks." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1779835631&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Ford, Jackson Walker. "Production of acetic acid from the fermentation of synthesis gas." Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-07062004-133352.
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PAOLUCCI, VALENTINA. "Graphene-like nanoscale gas sensors from material synthesis to applications." Doctoral thesis, Università degli Studi dell'Aquila, 2019. http://hdl.handle.net/11697/143506.
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A very widespread area of application for nanomaterials is that of gas sensors. Until now, in fact, the measurement of pollutants in the air or in gaseous currents, has always been carried out through the use of traditional techniques, very effective, but long and often complicated. The use of solid-state gas sensors, devices capable of transforming chemical information, such as the concentration of a pollutant, into an electrical signal through the combined action of a receptor and a transducer, is considered the future in the field of environmental monitoring, as it allows simple, immediate measures and involves the use of small, even portable devices.
In this work nanomaterials have been used as gas sensors, thus exploiting their properties to significantly modify the electrical resistance following exposure to small concentrations of oxidizing and reducing gases.
Material’s evolution has been followed from the synthesis to the final application as gas sensors. In particular Transition Metal Dichalcogenides exfoliation process to produce high quality and high quantity of mono to few layer flakes has been set up, and once the final product has been tested, his performances have been optimized by combination with other materials. The design of the exfoliation process has been developed in light of the possibility of massive production and eventually the scalability of the process itself.
Morphological characterization of materials was carried out by means of Electron Microscopy (TEM and SEM), Atomic Force Microscopy, X-ray Diffraction and X-ray Photoelectron Spectroscopy. The electrical characterizations have been carried out by a laboratory equipment. Target gases such as H2 and NO2 with concentrations like those found in pollute environments were investigated.
This PhD work has developed through relationships with various research groups including the Departments of Physics and Industrial Engineering of the University of L'Aquila, the Department of Industrial Engineering of the University of Padova and the Department of Chemistry of the University of Sassari.
In particular, this research has been aimed to:
- Exfoliation of mono to few layered 2D Transitional Metal Dichalcogenides (TMDs) by grinding assisted probe sonication technique and optimization of exfoliation process;
- Investigation of the effect of the exfoliation on the surface chemistry of WS2;
- The morphological, microstructural and electrical characterization of synthesized sensing materials to define factors influencing gas sensing properties;
- Investigation on the gas sensing properties of above-mentioned nanostructured semiconductors to target gases such as H2, NO2, and humidity under simulated conditions.
- Synthesis and investigation of gas sensing properties of traditional semiconductor Metal Oxide Sensors (MOS).
The main achievements earned during this PhD program have been:
- Design of a reproducible and controllable exfoliation procedure to fabricate pristine mono and few layered WS2, by means of grinding assisted probe sonication yielding suspension of flake of average lateral size of 100 nm and thickness of 6 nm (less than 10 layers per flake)
- Control of the surface oxidation and thermal stability of exfoliated WS2 flakes
- Application of the exfoliated material to produce gas sensors, with complete understanding of the role of WS2/WO3, able to detect NO2 at concentration of 200 ppb and H2 5 ppm.
- Improvement of of the gas sensing performances of WS2 by the combination of graphene oxide to enhance conductivity and improvement of the response/recovery of the sensor by using light irradiation
- Improvement of of the gas sensing performances of traditional metal oxide sensors by adding different doping elements during synthesis.
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Hughes, Dimitri. "Facilitated characterization of a catalytic partial oxidation fuel reformer using in situ measurements." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31646.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010.Committee Co-Chair: Haynes, Comas; Committee Co-Chair: Wepfer, William; Committee Member: Jeter, Sheldon. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Roso, Casares Sergio. "Synthesis and gas sensing properties of single crystalline metal-oxide nanostructures." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/402468.
Full textAbstract:
A la present tesis doctoral, s'han produït diferents tipus de nanoestructures basades en òxids metàl·lics, com per exemple nanofils de ZnO i octaedros d'In2O3, utilitzant el mètode de Deposició Química de Vapor (CVD) a altes temperatures.
Per a la detecció d'òxid de nitrogen, s'ha descobert que la resposta dels nanofils d'ZnO està directament relacionada amb la quantitat de defectes presents en el material. Com més gran es el nombre de defectes, major és la resposta al diòxid de nitrogen. Tanmateix, per a la detecció d'etanol, la mostra que contenia un nombre mig de defectes, va ser la que dóna millors resultats.
Pel que fa als octaedres de In2O3, podem dir que els octaedres d'In2O3 pur són excel·lents candidats per a la detecció de NO2, ja que tenen una excel·lent sensibilitat (0.43 ppb-1) a baixes temperatures (130ºC), mentres que la resposta a altres gasos com H2 és dos ordres de magnituds inferior en les mateixes condicions. A més a més, en presencia d'humitat, s'incrementa la sensibilitat a NO2 i, a la vegada, es redueix la sensibilitat a H2, pel que la selectivitat a NO2 també es veu incrementada.
Finalment, utilitzant l'espectroscopia DRIFT, s'ha analitzat l'In2O3 expost a 1 ppm de NO2 a diferents temperatures i s'ha descobert que el mecanisme proposat per a descriure el procés de sensat es bastant més complicat del que s'ha reportat fins ara.
Com a resultat de tots aquests experiments, s'ha donat un pas edanvant en l'explicació dels mecanismes de sensat dels nanofils d'ZnO i els octaedres de In2O3 a diferents temperatures.En la presente tesis doctoral, se han producido diferentes tipos de nanoestructuras basadas en oxidos metalicos, como por ejemplo nanohilos de ZnO y ocaedros de In2O3, utilizando el método de Deposición Química de Vapor (CVD) a altas temperaturas. Para la detección de dióxido de nitrógeno, se ha descubierto que la respuesta de los nanohilos de ZnO está directamente correlacionada con la cantidad total de defectos presentes en el material. Cuanto mayor es el número de defectos, mayor es la respuesta al dióxido de nitrógeno. Sin embargo, para la detección de etanol, la muestra que contenía un número medio de defectos fue la que dio mejores resultados. Por lo que respecta a los octaedros de In2O3, podemos decir que los octaedros de In2O3 puro son excelentes candidatos para la detección de NO2, ya que poseen una excelente sensibilidad (0.43 ppb-1) a bajas temperaturas (130ºC), mientras que la respuesta a otros gases como H2 es dos órdenes de magnitud inferior en las mismas condiciones. Además, en presencia de humedad, se incrementa la sensibilidad a NO2 y, a la vez, se reduce la sensibilidad a H2, por lo que la selectividad hacia NO2 tambien se ve incrementada. Finalmente, utilizando la espectroscopia DRIFT, se ha analizado el In2O3 expuesto a 1 ppm de NO2 a diferentes temperaturas y se ha descubierto que el mecanismo propuesto para describir el proceso de senado es bastante más complicado que lo que se ha publicado hasta ahora. Como resultado de todos estos experimentos, se ha arrojado luz nueva sobre los mecanismos de sensado de los nanohilos de ZnO y los octahedros de In2O3 a diferentes temperaturas.
In the present doctoral thesis, several metal oxide nanostructures such as ZnO nanowires and In2O3 octahedra via a chemical vapour deposition (CVD) method at high temperatures. For the detection of nitrogen dioxide, it was found that the response of ZnO nanowires was directly correlated to the overall amount of defects of the material. The higher the number of defects is, the higher the response to nitrogen dioxide is. On the other hand, for the detection of ethanol, ZnO nanowires with an intermediate number of defects in which surface defects were dominant led to the best results. Additionally, regarding the In2O3 octahedra, we can say that pure In2O3 octahedra are excellent for detecting NO2 gas with an outstanding sensitivity (0.43 ppb-1) at low temperatures (130ºC), while the response to H2 remains two orders of magnitude lower under the same conditions. In addition, the presence of humidity increases the sensitivity to NO2 and, at the same time, reduces the response to H2, which results in an increased selectivity. Finally, by making use of the DRIFT spectroscopy, we have analyzed In2O3 material towards 1 ppm of NO2 at different temperatures and, it has been found that the mechanism proposed for the gas sensing is far more complicated than previously reported. As a result of these experiments, new light on the sensing mechanism of ZnO and In2O3 material towards NO2 gas at different temperatures has been shed.
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Mu, Bin. "Synthesis and gas adsorption study of porous metal-organic framework materials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41097.
Full textAbstract:
Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) have become the focus of intense study over the past decade due to their potential for advancing a variety of applications including air purification, gas storage, adsorption separations, catalysis, gas sensing, drug delivery, and so on. These materials have some distinct advantages over traditional porous materials such as the well-defined structures, uniform pore sizes, chemically functionalized sorption sites, and potential for post-synthetic modification, etc. Thus, synthesis and adsorption studies of porous MOFs have increased substantially in recent years. Among various prospective applications, air purification is one of the most immediate concerns, which has urgent requirements to improve current nuclear, biological, and chemical (NBC) filters involving commercial and military purposes. Thus, the major goal of this funded project is to search, synthesize, and test these novel hybrid porous materials for adsorptive removal of toxic industrial chemicals (TICs) and chemical warfare agents (CWAs), and to install the benchmark for new-generation NBC filters. The objective of this study is three-fold: (i) Advance our understanding of coordination chemistry by synthesizing novel MOFs and characterizing these porous coordination polymers; (ii) Evaluate porous MOF materials for gas-adsorption applications including CO2 capture, CH4 storage, other light gas adsorption and separations, and examine the chemical and physical properties of these solid adsorbents including thermal stability and heat capacity of MOFs; (iii) Evaluate porous MOF materials for next-generation NBC filter media by adsorption breakthrough measurements of TICs on MOFs, and advance our understanding about structure-property relationships of these novel adsorbents.
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Warwick, Barry School of Chemical Engineering & Industrial Chemistry UNSW. "Synthesis, purification and micronisation of copper indomethacin using dense gas technology." Awarded by:University of New South Wales. School of Chemical Engineering and Industrial Chemistry, 2001. http://handle.unsw.edu.au/1959.4/17876.
Full textAbstract:
The primary aim of this work was to provide an alternative method of synthesis of the non-steroidal anti-inflammatory drug copper indomethacin (Cu-Indo) and to produce alternative forms of the drug to increase its marketability. Dense gases as anti-solvents were used to achieve these aims. The study involved the synthesis, purification, micronisation and co-precipitation of Cu-Indo with polyvinylpyrrolidone (PVP) using dense carbon dioxide as an anti-solvent. Initially the volumetric and solubility behaviours of the solvent???anti-solvent systems were investigated to determine the optimum processing conditions. The solubility of Cu-Indo in an expanded solution was found to be a complex function of the solvent and other solutes. Copper indomethacin was successfully synthesised and purified in a single vessel using dense carbon dioxide as an anti-solvent. Drug yields of 98 % and purities near 100 % were achieved at optimum conditions with the advantages of less residual solvent in the drug, less solvent waste, reduced processing time and increased yields over the conventional synthesis process. Copper indomethacin was produced in a variety of morphologies and particle sizes using dense carbon dioxide as an anti-solvent. An investigation of the effect of process parameters on the particle characteristics showed that solute concentration was the dominant variable. Spherical particles with diameters less than 8 mm were obtained at optimum conditions. The immediate benefit of micronising Cu-Indo was demonstrated with an eight fold increase in dissolution rate when compared to the conventionally produced drug. Polyvinylpyrrolidone was successfully co-precipitated with Cu-Indo using dense carbon dioxide as an anti-solvent. The PVP???Cu-Indo co-precipitates were found to increase the solubility of the drug in ethanol with a 36 fold solubility enhancement at optimum conditions. The use of dense carbon dioxide as anti-solvent in this work demonstrates the potential of the GAS and ASES processes in the pharmaceutical industry. Copper indomethacin was synthesised, purified and micronised in a single vessel at a substantial saving in terms of time and solvent usage. The micronisation of Cu-Indo and the formation of the PVP???Cu-Indo co-precipitate provided alternative forms of the drug substantially increasing its marketability.
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Blanksby, Stephen J. ""Gas phase synthesis of interstellar cumulenes : mass spectrometric and theoretical studies" /." Title page, contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phb6423.pdf.
Full textAbstract:
Thesis (Ph.D.)-- University of Adelaide, Dept. of Chemistry, 1999.Copies of author's previously published articles inserted. Supplement entitled: Addressing referee concerns, stapled to back end paper (5 leaves). Bibliography: leaves 199-212.
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Putkham, Apipong. "Synthesis, characterisation and gas absorption studies for metal organic framework materials." Thesis, University of Newcastle Upon Tyne, 2010. http://hdl.handle.net/10443/909.
Full textAbstract:
Recently, porous metal organic framework materials (MOFs) have attracted considerable attention due to the wide range of possible applications of the materials in 1) gas storage, purification and separation; 2) as catalysts and catalyst supports; and 3) for adsorption of environmentally unfriendly species. This study has involved the synthesis, characterisation and determination of the adsorption/desorption characteristics of functionalised porous metal organic framework materials. The overall objective was to increase understanding of the role of surface functional groups and framework flexibility in determining the adsorption characteristics of gases and vapours and assess the possible applications of these materials for gas storage and separation. Adsorption of hydrogen, nitrogen, oxygen and argon were studied in order to investigate the possible applications of metal organic framework NEW-1 in gas storage and air separation. In case of the air separation, adsorption characteristics of O2, N2, and Ar on metal organic framework NEW-1, mixed-zinc/copper organic framework (M’MOF-1) and a carbon based molecular sieve (CMS-40) were compared. The crucial factors such as molecular size and shape in relation to pore structure in determining the adsorption characteristics on materials were investigated. Selected kinetic models i.e. stretched exponential model (SE), double stretched exponential model (DSE) were used to determine the kinetic adsorption parameters. Also, the isosteric enthalpies of gases adsorption at zero surface coverage were determined. The results show that very narrow pores are required in metal organic frameworks to achieve kinetic selectivity similar to CMS-40.
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Du, Toit Ernest. "The direct conversion of synthesis gas to chemicals / Ernest du Toit." Thesis, Potchefstroom University for Christian Higher Education, 2002. http://hdl.handle.net/10394/9624.
Full textAbstract:
The catalytic conversion of synthesis gas, obtainable from the processing of coal, biomass or
natural gas, to a complex hydrocarbon product stream can be achieved via the Fischer-Tropsch
process. The Fischer-Tropsch synthesis process has evolved from being mainly a fuel producing
process in the early 1950's to that of a solvent and speciality wax production process towards the
end of the 1970's. From the early 1980's there has been a clear shift towards the production of
commodity chemicals in addition to fuel.
Advances in reactor technology, volatile crude oil markets and a world trend towards "clean"
fuels may cause a shift towards coal and natural gas as the feedstock of choice for the chemical
industry. Fischer-Tropsch plants are capital intensive ventures due to the complexity of the
process. Viable returns on such projects can only be realised by adding value to the products
obtained from such processes. The chemical industry places a high premium on certain
chemicals such as olefins and higher alcohols. More selective production of such chemicals can
contribute to increased 'profitability and thus more economically viable processes. The C8+
alcohol and C6+ olefin product range can be labelled as valuable chemicals. A major limitation
in the traditional Fischer-Tropsch process is the low selectivity towards these valuable chemicals.
The product distribution observed for a Fischer-Tropsch catalyst system conforms to the SchulzFlory
polymerisation mechanism, which is inherently non-selective.
This investigation deals with an iron-based catalyst that can best be described as a chemically
selective Fischer-Tropsch catalyst. The product spectrum achieved with this so-called "ChemFT"
catalyst can be seen as a breakthrough in terms of producing chemicals directly from syngas.
The investigation covers the following aspects:
a review of the development of the ChemFT catalyst used in this investigation,
the characterisation of the ChemFT catalyst,
an experimental verification of the catalyst product spectrum with respect to alcohols and
olefins, on both laboratory and pilot plant scale,
the development of rate equations for'Fischer-Tropsch and Water-Gas-Shift activity. Experimental performance results of the ChemFT catalyst show high selectivity towards the
desired alcohol product compared to traditional low temperature iron catalysts (8- 14 C atom%
vs. 2 - 4 C atom %). Similar olefin selectivity is obtainable with lower long chain paraffin
selectivity (little or no wax formation). It is concluded that the ChemFT catalyst differs from
conventional Fischer-Tropsch iron catalysts as far as selectivity and typical process conditions
are concerned. Published reaction rate equations were evaluated for applicability to such a
scenario. Known Fischer-Tropsch reaction rate equations described the catalyst kinetics fairly
well. The theoretical base thereof was further improved by modifYing the equations to include
the effect of catalyst vacant sites. Published Water-Gas-Shift rate equations did not adequately
describe the catalyst. It was shown that the accuracy of the Water-Gas-Shift equation could be
improved by modifYing it to account for C02 adsorption. Reaction rate equations for both the
Fischer-Tropsch and Water-Gas-Shift reaction rates that are valid in the typical operating
conditions are proposed.Thesis (PhD (Chemical Engineering))--Potchefstroom University for Christian Higher Education, 2003
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Santamaria-Mendia, Fernan. "Synthesis and characterisation of gas permeation through novel based polyimide membranes." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396631.
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