Journal articles: 'Thiele modulus'

1

Kennedy, K. J., and R. L. Droste. "Diffusional limitations of anaerobic biofilms." Canadian Journal of Civil Engineering 14, no. 5 (October 1, 1987): 631–37. http://dx.doi.org/10.1139/l87-093.

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Using an empirical determination of apparent kinetic parameters in the bulk mixed liquor, the intrinsic kinetic parameters of anaerobic biofilms developed at 35 °C during start-up and steady-state downflow stationary fixed film reactor operation were estimated. The apparent kinetic parameters of anaerobic biofilms are not significantly influenced by internal diffusion limitations. The apparent kinetic parameters of mature biofilms showed no significant trends with increased biofilm thickness up to 2.6 mm and increased apparent Thiele modulus up to 3.1. Key words: anaerobic, biofilm kinetics, Thiele modulus, wastewater, filter.

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Hartmann, Martin, Albert Gonche Machoke, and Wilhelm Schwieger. "Catalytic test reactions for the evaluation of hierarchical zeolites." Chemical Society Reviews 45, no. 12 (2016): 3313–30. http://dx.doi.org/10.1039/c5cs00935a.

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3

Markoš, Jozef, and Alena Brunovská. "Optimal catalyst activity distribution in fixed-bed reactor with catalyst deactivation." Collection of Czechoslovak Chemical Communications 54, no. 2 (1989): 375–87. http://dx.doi.org/10.1135/cccc19890375.

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In this paper the influence of the active catalyst location in a pellet on fixed-bed catalytic reactor performance is described. The optimal activity distribution as a function of an economic parameter (ratio of product and catalyst costs), Thiele modulus and Damkohler number is estimated.

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4

Zhokh, Alexey, and Peter Strizhak. "Thiele modulus having regard to the anomalous diffusion in a catalyst pellet." Chaos, Solitons & Fractals 109 (April 2018): 58–63. http://dx.doi.org/10.1016/j.chaos.2018.02.016.

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Sharma, Kritika, Shrihari Sankarasubramanian, Javier Parrondo, and Vijay Ramani. "Electrochemical implications of modulating the solvation shell around redox active organic species in aqueous organic redox flow batteries." Proceedings of the National Academy of Sciences 118, no. 34 (August 20, 2021): e2105889118. http://dx.doi.org/10.1073/pnas.2105889118.

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Organic and organometallic reactants in aqueous electrolytes, being composed of earth-abundant elements, are promising redox active candidates for cost-effective organic redox flow batteries (ORFBs). Various compounds of ferrocene and methyl viologen have been examined as promising redox actives for this application. Herein, we examined the influence of the electrolyte pH and the salt anion on model redox active organic cations, bis((3-trimethylammonio) propyl)- ferrocene dichloride (BTMAP-Fc) and bis(3-trimethylammonio) propyl viologen tetrachloride (BTMAP-Vi), which have exhibited excellent cycling stability and capacity retention at ≥1.00 M concentration [E. S. Beh, et al. ACS Energy Lett. 2, 639–644 (2017)]. We examined the solvation shell around BTMAP-Fc and BTMAP-Vi at acidic and neutral pH with SO42-, Cl−, and CH3SO3− counterions and elucidated their impact on cation diffusion coefficient, first electron transfer rate constant, and thereby the electrochemical Thiele modulus. The electrochemical Thiele modulus was found to be exponentially correlated with the solvent reorganizational energy (λ) in both neutral and acidic pH. Thus, λ is proposed as a universal descriptor and selection criteria for organic redox flow battery electrolyte compositions. In the specific case of the BTMAP-Fc/BTMAP-Vi ORFB, low pH electrolytes with methanesulfonate or chloride counterions were identified as offering the best balance of transport and kinetic requirements.

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Zeynali, Mohammad Ebrahim, and S. Hakim. "Diffusion Processes Affecting the Performance of Heterogeneous Catalysts: Part 1." Defect and Diffusion Forum 319-320 (October 2011): 107–15. http://dx.doi.org/10.4028/www.scientific.net/ddf.319-320.107.

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The diffusion processes taking place in heterogeneous catalytic systems have been discussed. Various diffusion mechanisms such as Knudsen diffusion, molecular diffusion, configurational diffusion and surface diffusion sensitivity in catalytic systems were investigated. The concentration gradients inside the catalyst pellet were obtained for various Thiele modulus. The Knudsen number was calculated and discussed for large and small pores. The transitional diffusion coefficient was determined for diethylbenzene. The experimental pore size distribution carves for an industrial and synthesized catalyst was obtained and the effect of pore size distribution on diffusion coefficient was discussed.

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UshaRani, Ramu, Lakshmanan Rajendran, and Marwan Abukhaled. "Approximations for the Concentration and Effectiveness Factor in Porous Catalysts of Arbitrary Shape: Taylor Series and Akbari-Ganji’s Methods." Mathematical Modelling of Engineering Problems 8, no. 4 (August 31, 2021): 527–37. http://dx.doi.org/10.18280/mmep.080405.

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A mathematical model of reaction-diffusion problem with Michaelis-Menten kinetics in catalyst particles of arbitrary shape is investigated. Analytical expressions of the concentration of substrates are derived as functions of the Thiele modulus, the modified Sherwood number, and the Michaelis constant. A Taylor series approach and the Akbari-Ganji's method are utilized to determine the substrate concentration and the effectiveness factor. The effects of the shape factor on the concentration profiles and the effectiveness factor are discussed. In addition to their simple implementations, the proposed analytical approaches are reliable and highly accurate, as it will be shown when compared with numerical simulations.

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Driessen, Rick T., Sascha R. A. Kersten, and Derk W. F. Brilman. "A Thiele Modulus Approach for Nonequilibrium Adsorption Processes and Its Application to CO2 Capture." Industrial & Engineering Chemistry Research 59, no. 15 (January 17, 2020): 6874–85. http://dx.doi.org/10.1021/acs.iecr.9b05503.

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Sharratt, P. N., and R. Mann. "Some observations on the variation of tortuosity with Thiele modulus and pore size distribution." Chemical Engineering Science 42, no. 7 (1987): 1565–76. http://dx.doi.org/10.1016/0009-2509(87)80161-6.

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10

Yang, Wei, Schalk Cloete, John Morud, and Shahriar Amini. "An Effective Reaction Rate Model for Gas-Solid Reactions with High Intra-Particle Diffusion Resistance." International Journal of Chemical Reactor Engineering 14, no. 1 (February 1, 2016): 331–42. http://dx.doi.org/10.1515/ijcre-2015-0127.

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AbstractAn approximate analytical expression for estimating the effectiveness factors of non-catalytic gas-solid reactions is proposed. The new expression is derived from the analytical solution for simple first order reactions (Ishida and Wen 1968. Comparison of kinetic and diffusional models for solid-gas reactions. AIChE Journal 14, 311–317. http://dx.doi.org/10.1002/aic.690140218). The scaled Thiele modulus concept is introduced to account for the variations of the reaction rate form that differs from the first order. The validity of the new expression is demonstrated for the reactions of different orders and of different forms via comparisons against a complete particle-reactor model using the collocation method for solving heat and mass fluxes inside the particles. In addition, the proposed approach is applied to redox reactions of ferric oxide where non-isothermal condition, net consumption of gaseous reactant, and parallel reactions are encountered. The results show that the effectiveness factor method compared well with the orthogonal collocation method over a wide range of Thiele moduli, reaction orders and reaction forms. Therefore, the proposed expression can serve as a generic replacement for more complex and computationally expensive combined particle-reactor modelling which is often employed in reactor systems with significant intra-particle diffusion resistances.

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11

Gültekin, S. "Mass Transfer with Chemical Reactions in Porous Catalysts: A Discussion on the Criteria for the Internal and External Diffusion Limitations." Defect and Diffusion Forum 334-335 (February 2013): 279–83. http://dx.doi.org/10.4028/www.scientific.net/ddf.334-335.279.

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In this study, criteria for internal mass transfer given in the literature were investigated by considering tortuosity (τ) in the porous catalysts. Uncertainties in τ, which may have values between 2 to 7, have a big impact on the effective diffusivity (Deff) which also affects the Thiele Modulus (Φ). Since effectiveness factor (η) is function of Φ, then the criteria given for limitations are questionable. The value of Deff, and in turn the value of Φ calculated for the τ=2 to 7. At low Φ the effects are very small, but when the Φ increases the effect becomes more pronounced. As a result, when using internal mass transfer limitations, one has to be very careful not to get trapped by the disguised kinetics, results of which may end up with disaster.

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Shunmugham, Loghambal, and L. Rajendran. "Analytical Expressions for Steady-State Concentrations of Substrate and Oxidized and Reduced Mediator in an Amperometric Biosensor." International Journal of Electrochemistry 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/812856.

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A mathematical model of modified enzyme-membrane electrode for steady-state condition is discussed. This model contains a nonlinear term related to enzyme kinetics reaction mechanism. The thickness dependence of an amperometric biosensor is presented both analytically and numerically where the biological layer is immobilized between a solid substrate and permeable electrode. The analytical expressions pertaining to the concentration of species and normalized current are obtained using the Adomian decomposition method (ADM). Simple and approximate polynomial expressions of concentrations of an oxidized mediator, substrate, and reduced mediator are derived for all possible values of parametersϕO2(Thiele modulus),BO(normalized surface concentration of oxidized mediator), andBS(normalized surface concentration of substrate). A comparison of the analytical approximation and numerical simulation is also presented. A good agreement between theoretical predictions and numerical results is observed.

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Li, Mingchun, Baoting Wang, Aili Tao, and Shengfei Li. "Gas Sensing Properties of Cobalt Titanate with Multiscale Pore Structure: Experiment and Simulation." Sensors 20, no. 6 (March 24, 2020): 1787. http://dx.doi.org/10.3390/s20061787.

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A diffusion-reaction coupled model was presented to investigate the effects of multiscale pore structure characteristics on gas sensing properties. A series of CoTiO3 powders with different pore size distributions were fabricated by sol-gel method. Experimental results on cobalt titanate thick films show that a well-defined multiscale pore structure is particularly desired for the improvement of sensing performance, instead of just increasing the specific surface area. The theoretical responses of sensing elements with different pore size distributions were derived and compared with experimental data on CoTiO3 sensors exposed to ethanol. The calculated sensitivities considering the influence of pore size changes were also found to be in agreement with the experimental results. A dimensionless Thiele modulus Th was introduced for assessing the critical point corresponding to the transformation from surface reaction-controlled sensitivity into diffusion-controlled sensitivity.

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14

Hanika, Jiří, and Vladimíra Ehlová. "Modelling of internal diffusion inside a catalyst particle with non-uniform radial activity profile for parallel reactions." Collection of Czechoslovak Chemical Communications 54, no. 1 (1989): 81–90. http://dx.doi.org/10.1135/cccc19890081.

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Numerical solution of the system of diffusion equations which describe a system of parallel reactions under the conditions of internal diffusion in a non-isotropic spherical catalyst particle was carried out in this paper. The solution of the problem was sought for various radial activity profile corresponding to the concentration profile of active component in a particle of supported catalyst and for various values of the Thiele modulus of both parallel reactions. Further, the effect of reaction order of single reactions (zeroth or first) with respect to the effectiveness factor of the internal diffusion and to the selectivity of the main reaction was investigated. It is evident from the results that the change of the activity profile in the particle has a great effect on the selectivity and on the effectiveness factor of the internal diffusion.

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15

Valencia, Pedro, and Francisco Ibañez. "Estimation of the Effectiveness Factor for Immobilized Enzyme Catalysts through a Simple Conversion Assay." Catalysts 9, no. 11 (November 7, 2019): 930. http://dx.doi.org/10.3390/catal9110930.

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A novel methodology to estimate the effectiveness factor (EF) of an immobilized enzyme catalyst is proposed here. The methodology consists of the determination of the productivity of both the immobilized enzyme catalyst and its corresponding soluble enzyme, plotted as a function of the reaction conversion. The ratio of these productivities corresponds to the EF estimator of the catalyst. Conversion curves were simulated in a batch reactor with immobilized enzyme and soluble enzyme for different values of the S0/KM ratio and Thiele modulus (Φ) to demonstrate this hypothesis. Two different reaction orders were tested: first-order kinetic and Michaelis–Menten-based kinetic with product inhibition. The results showed that the ratio of productivities between the immobilized and soluble enzymes followed the behavior profile presented by the EF with satisfactory agreement. This simple methodology to estimate the EF is based on routine conversion experiments, thus avoiding the exhaustive kinetic and mass transfer characterization of the immobilized enzyme catalyst.

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16

Ahmedi, Afaf, Mahmoud Abouseoud, Amrane Abdeltif, and Couvert Annabelle. "Effect of Diffusion on Discoloration of Congo Red by Alginate Entrapped Turnip (Brassica rapa) Peroxidase." Enzyme Research 2015 (February 5, 2015): 1–9. http://dx.doi.org/10.1155/2015/575618.

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Enzymatic discoloration of the diazo dye, Congo red (CR), by immobilized plant peroxidase from turnip “Brassica rapa” is investigated. Partially purified turnip peroxidase (TP) was immobilized by entrapment in spherical particles of calcium alginate and was assayed for the discoloration of aqueous CR solution. Experimental data revealed that pH, reaction time, temperature, colorant, and H2O2 concentration play a significant role in dye degradation. Maximum CR removal was found at pH 2.0, constant temperature of 40°C in the presence of 10 mM H2O2, and 180 mg/L of CR. More than 94% of CR was removed by alginate immobilized TP after 1 h of incubation in a batch process under optimal conditions. About 74% removal efficiency was retained after four recycles. Diffusional limitations in alginate beads such as effectiveness factor η, Thiele modulus Φ, and effective diffusion coefficients (De) of Congo red were predicted assuming a first-order biodegradation kinetic. Results showed that intraparticle diffusion resistance has a significant effect on the CR biodegradation rate.

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Shokirov, U., S. Turabjanov, Rakhimova, and F. Badriddinova. "KINETICS OFPYRROLE FORM TICS OFPYRROLE FORMATIONFROM A TIONFROM ACETYLENE, AMMONIA AND AMINES." Technical science and innovation 2018, no. 4 (August 2, 2019): 24–29. http://dx.doi.org/10.51346/tstu-01.18.4.-77-0019.

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The research findings of the pyrrole formation from acetylene, ammonia and amines varying catalysts and reaction conditions have been studied in the work. The cadmium catalysts developed by us selectively lead to pyrroleformation using aluminum fluoride as a promoter. The change in the rate of acetylene consumption depending on the weight of the catalyst according to the Boreskov criterion shows that external diffusion does not influence under the conditions of T-573K and P_ (C_2 H_2) = 0.1 atm. The values of the rate of acetylene consumption of at 4, 2, 1, 0.5 mm sizes of catalyst grains with similar conditions, internal diffusion does not influence on the observed rate of acetylene consumption. Calculation on the Thiele modulus shows that the reaction of acetylene consumption does not experience intradiffusion inhibition. The presence of a noticeable amount of macropores in the porous catalyst grain eliminates the appearance of a temperature gradient and causes a high kinetic ability of the reaction

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Picioreanu, C., M. C. M. van Loosdrecht, and J. J. Heijnen. "Discrete-differential modelling of biofilm structure." Water Science and Technology 39, no. 7 (April 1, 1999): 115–22. http://dx.doi.org/10.2166/wst.1999.0341.

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A fully quantitative two- and three-dimensional approach for biofilm growth and structure formation has been developed. The present model incorporates the flow over the irregular biofilm surface, convective and diffusive mass transfer of substrate, bacterial growth and biomass spreading. A future model will also include a mechanism for biofilm detachment due to biofilm deformation stress. Any arbitrary shape of the carrier surface can be accommodated in the model, as well as multispecies and multisubstrate biofilms. Results of model simulations show that the ratio between nutrient transfer rate to the biofilm and the bacterial growth rate influences to a great extent the biofilm roughness and porosity. A low mass transfer rate, i.e., low Reynolds numbers or high values of Thiele modulus, results in the development of a rough and open biofilm. When the biofilm growth is not limited by the substrate availability but by the rate of bacterial metabolism, the biofilm forms as a compact and homogeneous structure. The multidimensional biofilm modelling approach we used is very suitable for theoretical investigation of factors that affect biofilm structure and ecology.

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Mariani, Néstor J., Clarisa Mocciaro, Sergio D. Keegan, Osvaldo M. Martínez, and Guillermo F. Barreto. "Evaluating the effectiveness factor from a 1D approximation fitted at high Thiele modulus: Spanning commercial pellet shapes with linear kinetics." Chemical Engineering Science 64, no. 11 (June 2009): 2762–66. http://dx.doi.org/10.1016/j.ces.2009.02.044.

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Xavier, Joao B., Cristian Picioreanu, Suriani Abdul Rani, Mark C. M. van Loosdrecht, and Philip S. Stewart. "Biofilm-control strategies based on enzymic disruption of the extracellular polymeric substance matrix – a modelling study." Microbiology 151, no. 12 (December 1, 2005): 3817–32. http://dx.doi.org/10.1099/mic.0.28165-0.

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A kinetic model is proposed to assess the feasibility of strategies for the removal of biofilms by using substances that induce detachment by affecting the cohesiveness of the matrix of extracellular polymeric substances (EPSs). The model uses a two-state description of the EPS (natural EPS and compromised EPS) to provide a unified representation of diverse mechanisms of action of detachment-promoting agents (DPAs), which include enzymes that degrade the EPS and other agents described in the literature. A biofilm-cohesiveness factor describes local increases in detachment rates resultant from losses in cohesive strength. The kinetic model was implemented in an individual-based biofilm-modelling framework, including detachment rates dependent on local cohesiveness. The efficacy of treatments with DPAs was assessed by three-dimensional model simulations. Changes in treatment efficacy were evaluated quantitatively by using a Thiele modulus, which quantifies the relationship between diffusion of the DPA through the biofilm matrix and DPA decay rate, and a Damköhler number relating the rate of EPS reaction with a DPA and the rate of EPS production by the micro-organisms in the biofilm. This study demonstrates the feasibility and limits of implementing biofilm-control strategies based on attacking the EPS.

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Fawaz, Elyssa G., Darine A. Salam, Severinne S. Rigolet, and T. Jean Daou. "Hierarchical Zeolites as Catalysts for Biodiesel Production from Waste Frying Oils to Overcome Mass Transfer Limitations." Molecules 26, no. 16 (August 12, 2021): 4879. http://dx.doi.org/10.3390/molecules26164879.

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Hierarchical crystals with short diffusion path, conventional microcrystals and nanocrystals of ZSM-5 zeolites were used for biodiesel production from waste frying oils and were assessed for their catalytic activity in regard to their pore structure and acidic properties. Produced zeolites were characterized using XRD, nitrogen adsorption–desorption, SEM, TEM, X-ray fluorescence, and FTIR. Pore size effect on molecular diffusion limitation was assessed by Thiele modulus calculations and turnover frequencies (TOF) were used to discuss the correlation between acidic character and catalytic performance of the zeolites. Owing to the enhanced accessibility and mass transfer of triglycerides and free fatty acids to the elemental active zeolitic structure, the catalytic performance of nanosponge and nanosheet hierarchical zeolites was the highest. A maximum yield of 48.29% was reached for the transesterification of waste frying oils (WFOs) using HZSM-5 nanosheets at 12:1 methanol to WFOs molar ratio, 180 °C, 10 wt % catalyst loading, and 4 h reaction time. Although HZSM-5 nanosponges achieved high conversions, these more hydrophilic zeolites did not function according to their entire acidic strength in comparison to HZSM-5 nanosheets. NSh-HZSM5 catalytic performance was still high after 4 consecutive cycles as a result of the zeolite regeneration.

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Kumoro, Andri Cahyo, Diah Susetyo Retnowati, and Ratnawati Ratnawati. "Kinetics of Starch Degradation during Extrusion Cooking of Steady State Flow Konjac (Amorphophallus oncophyllus) Tuber Flour in a Single Screw Extruder." Bulletin of Chemical Reaction Engineering & Catalysis 15, no. 2 (July 20, 2020): 591–602. http://dx.doi.org/10.9767/bcrec.15.2.8125.591-602.

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The presence of glucomannan in Konjac (Amorphophallus oncophyllus) tuber flour has promoted its various applications, especially in the food, drink, drug delivery and cosmetics. Starch is the main impurity of Konjac tuber flour. Although the common wet refining method may result in a high purity Konjac tuber flour, it is very tedious, time consuming and costly. This research aimed to study the kinetics of starch degradation in the extrusion cooking process of dry refining method to produce high quality Konjac tuber flour. In this research, Konjac tuber flour with 20% (w/w) moisture was extruded in a single screw extruder by varying screw speeds (50, 75, 100, 125, 150 and 175 rpm) and barrel temperatures (353, 373, 393, 413 and 433 K). The results showed that the starch extrusion cooking obeys the first reaction order. The reaction rate constant could be satisfactorily fitted by Arrhenius correlation with total activation energy of 6191 J.mol−1 and pre-exponential factor of 2.8728×10−1 s−1. Accordingly, thermal degradation was found to be the primary cause of starch degradation, which shared more than 99% of the energy used for starch degradation. Based on mass Biot number and Thiele modulus evaluations, chemical reaction was the controlling mechanism of the process. The results of this research offer potential application in Konjac tuber flour refining process to obtain high quality flour product. Copyright © 2020 BCREC Group. All rights reserved

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23

Alopaeus, Ville. "Approximating Catalyst Effectiveness Factors with Reaction Rate Profiles." Catalysts 9, no. 3 (March 13, 2019): 255. http://dx.doi.org/10.3390/catal9030255.

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A novel approximate solution for catalyst effectiveness factors is presented. It is based on carefully selected approximate reaction rate profiles, instead of typical assumption of composition profiles inside the catalyst. This formulation allows analytical solution of the approximate model, leading to a very simple iterative solution for effectiveness factor for general nonlinear reaction stoichiometry and arbitrary catalyst particle shape. The same model can be used with all practical Thiele modulus values, including multicomponent systems with inert compounds. Furthermore, the correct formulation of the underlying physical model equation is discussed. It is shown that an incorrect but often-used model formulation where convective mass transfer has been neglected may lead to much higher errors than the present approximation. Even with a correctly formulated physical model, rigorous discretization of the catalyst particle volume may have unexpectedly high numerical errors, even exceeding those with the present approximate solution. The proposed approximate solution was tested with a number of examples. The first was an equimolar reaction with first order kinetics, for which analytical solutions are available for the standard catalyst particle geometries (slab, long cylinder, and sphere). Then, the method was tested with a second order reaction in three cases: 1) with one pure reactant, 2) with inert present, and 3) with two reactants and non-stoichiometric surface concentrations. Finally, the method was tested with an industrially relevant catalytic toluene hydrogenation including Maxwell-Stefan formulation for the diffusion fluxes. In all the tested systems, the results were practically identical when compared to the analytical solutions or rigorous finite volume solution of the same problem.

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Sulaiman, Sarina, and M. H. M. Amin. "Fish Bone-Catalyzed Methanolysis of Waste Cooking Oil." Bulletin of Chemical Reaction Engineering & Catalysis 11, no. 2 (August 20, 2016): 245. http://dx.doi.org/10.9767/bcrec.11.2.556.245-249.

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The use of cheaper alternative such as waste cooking oil as substitute to vegetable oil can reduce the overall production cost of biodiesel. This research focuses on the investigation of the kinetic of waste cooking oil methanolysis using heterogeneous waste catalyst. Fish bone waste was used as the catalyst for the methanolysis of waste cooking oil. The kinetic data obtained from this study can be used to optimize the process of biodiesel production. The effects of temperature and catalyst amount were varied between 50- 65 °C and 4-10 wt % respectively. The kinetic of transesterification of waste oil, the reaction rate constant (k) and activation energy (EA) at 55, 65 and 65 °C were determined. The highest yield of biodiesel, 86 % were achieved at 6 wt% of catalyst amount, mixing of 300 rpm, methanol to oil ratio of 18:1 and reaction temperature of 65 °C. The activation energy (Ea) was 34.12 kJ/mol. This study also proves that transesterification process is not affected by the internal mass transfer due to the Thiele modulus value between 0-1.69. Copyright © 2016 BCREC GROUP. All rights reservedReceived: 22nd January 2016; Revised: 2nd February 2016; Accepted: 17th February 2016How to Cite: Sulaiman, S., Amin, M.H.M. (2016). Fish Bone-Catalyzed Methanolysis of Waste Cooking Oil. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2): 245-249 (doi:10.9767/bcrec.11.2.556.245-249)Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.556.245-249

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Zhou, Yue, Jie Hao, and Dongbing Zhao. "Divergent synthesis of 3-substituted thieno[3,4-b]thiophene derivatives via hydroxy-based transformations." Materials Chemistry Frontiers 3, no. 7 (2019): 1422–26. http://dx.doi.org/10.1039/c9qm00128j.

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Modular assembly of 3-substituted thieno[3,4-b]thiophenes: we have developed the first Pd-catalytic method to access 3-hydroxythieno[3,4-b]thiophene-2-carboxylate, which can be widely utilized for modular assembly of structurally diverse 3-substituted thieno[3,4-b]thiophene derivatives.

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FANG, Yuanxiang, and Rakesh GOVIND. "A New Thiele's Modulus for the Monod Biofilm Model." Chinese Journal of Chemical Engineering 16, no. 2 (April 2008): 277–86. http://dx.doi.org/10.1016/s1004-9541(08)60075-0.

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Valencia, P. L., S. A. Flores, and A. Abakarov. "Temperature effect on heterogeneous enzyme catalyzed reaction: Thièle modulus and effectiveness factor analysis." Journal of Biotechnology 150 (November 2010): 388. http://dx.doi.org/10.1016/j.jbiotec.2010.09.491.

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Osney Pérez, Ones, Lourdes Zumalacárregui De Cárdenas, and Osvaldo Gozá León. "Modelación Matemática de Columnas de Destilación Alcohólica." Publicaciones e Investigación 5, no. 1 (April 13, 2011): 29. http://dx.doi.org/10.22490/25394088.592.

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En este trabajo se presenta una propuesta de módulos de cálculo para la ampliación del simulador modular STA 4.0, orientado a la industria azucarera, con el objetivo de llevar a cabo el cálculo y análisis en destilerías de etanol. Se desarrollaron los módulos de cálculo para la simulación de las columnas que conforman el área de destilación, teniendo en cuenta los balances de materiales y energía, las relaciones de equilibrio y las propiedades termodinámicas del sistema etanol-agua. Para la determinación de las etapas teóricas en las columnas se hace uso del método de Ponchon-Savarit. Para la columna destiladora, se estableció una comparación entre los resultados obtenidos con los que ofrece el método de McCabe-Thiele. Se ilustra la aplicación de estos módulos de cálculo de destilerías de etanol a un caso real, demostrando su validez

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Hanyka, Jiří, and Alena Fialová. "The course of consecutive reactions inside a nonisotropic catalyst particle, affected by internal difusion." Collection of Czechoslovak Chemical Communications 51, no. 1 (1986): 54–65. http://dx.doi.org/10.1135/cccc19860054.

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A system of differential equations for consecutive reactions inside a nonisotropic catalyst particle under conditions of internal diffusion is solved. The system of diffusion equations for the spherical geometry of the catalyst grain is numerically solved by using the collocation method. The solution is sought for various radial activity profiles across the catalyst particle and for various values of Thiele's modulus for the two consecutive reactions. The effect of the reaction orders with respect to the reactants on the degree of utilization of the internal catalyst surface and on the reaction selectivity is examined.

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Gupta, Murlidhar, Andrew McFarlan, Leslie Nguyen, and Fernando Preto. "Design and development of a novel centrifuge ablative pyrolysis approach for biomass conversion to bio-oil and bio-char." E3S Web of Conferences 61 (2018): 00016. http://dx.doi.org/10.1051/e3sconf/20186100016.

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Pyrolysis has evolved as a key pre-treatment step to produce renewable fuels and chemicals from agricultural and forestry residues. In the past few years, there have been different directions in the development of pyrolysis reactors. For example, in vortex and cyclone approaches, biomass particles are suspended in a flow of high supersonic velocities to ensure enough centrifugal forces for pressing the particles against the heated reactor surface. Although simple in design, the requirement of large volumes of carrier gases necessitates cumbersome downstream gas separation, resulting in thermodynamic penalties and higher capital equipment costs. In ablative systems, with little or no carrier gases, the key challenge relates to using an appropriate mechanism to continuously apply forces on biomass particles during pyrolysis. In a recent alternative approach, thermo-mechanical rotors at very high rpm have been used to create the required centrifugal forces for pressing the biomass particles against the heated walls of a concentric shell. In the current approach, a modular centrifuge pyrolysis system has been designed using Biot and Thiele numbers as key constraints for characterizing ablative regimes. Unlike other centrifuge pyrolysis reactors, the novel rotor mechanism incorporated in this reactor system facilitates constant centrifugal force as well continuous propagation of biomass feeds. The 10 kg/hr thermo-mechanical pyrolysis system has been successfully commissioned using hardwood sawdust. Properties of bio-oil and bio-char produced in this new reactor have been compared to products from fluid bed pyrolysis system. In addition to its compact and modular design suitable for mobile pyrolysis units, it can be operated in variable regimes of pyrolysis, e.g., slow to fast modes, allowing adjustable product distribution.

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Sun, Pan-Pan, Tae-Young Kim, Hyeon Seo, and Sung-Yong Cho. "Recovery of Copper(II) and Silver(I) from Nitrate Leaching Solution of Industrial Dust via Solvent Extraction with LIX63." Metals 11, no. 8 (August 17, 2021): 1300. http://dx.doi.org/10.3390/met11081300.

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A nitrate leachate containing Cu(II), Ag(I), Ni(II), Mg(II), and Al(III) was obtained during the leaching of industrial dust, which arises during the pyrometallurgy of spent camera modules. To separate and recover Cu(II) and Ag(I) from the leaching solution, solvent extraction experiments using 5,8-diethyl-7-hydroxydodecan-6-oxime (LIX63) were conducted. LIX63 was found to selectively extract Cu(II) and Ag(I) over other metal ions (Ni(II), Mg(II), and Al(III)) at low nitric acid concentrations. The extraction efficiency of Cu(II) was more affected than that of Ag(I) by the acidity of the feed solution and the LIX63 concentration in the organic phase. Cu(II) and Ag(I) were simultaneously extracted using 2 mol/L LIX63. Cu(II) was separated from the loaded LIX63 via stripping with 4 mol/L HNO3, whereas Ag(I) was recovered via stripping with 0.1 mol/L thiourea after the removal of Cu(II). McCabe–Thiele diagrams for the extraction and stripping of Cu(II) and Ag(I) were constructed. The complete extraction of Cu(II) and Ag(I) was confirmed via counter-current extraction. Moreover, stripping simulation tests confirmed that higher than 99.99% of Cu(II) and 99.2% of Ag(I) were stripped. The purities of Cu(II) and Ag(I) in the recovered solution were 95.2% and 99.993%, respectively. A process flow chart for the recovery of Cu(II) and Ag(I) from the nitrate leachate of the target industrial dust was also provided.

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32

Kodesho, Taiki, Keigo Taniguchi, Takuya Kato, Shougo Mizoguchi, Yoshiki Yamakoshi, Kota Watanabe, Mineko Fujimiya, and Masaki Katayose. "Relationship between shear elastic modulus and passive force of the human rectus femoris at multiple sites: a Thiel soft-embalmed cadaver study." Journal of Medical Ultrasonics 48, no. 2 (February 12, 2021): 115–21. http://dx.doi.org/10.1007/s10396-020-01076-w.

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33

Wang, Yaxin, Edward A. Evans, Christopher S. Kovach, Uziel Landau, and John C. Angus. "Nucleation and Growth Processes During the Chemical Vapor Deposition of Diamond." MRS Proceedings 363 (1994). http://dx.doi.org/10.1557/proc-363-127.

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AbstractIn situmicrobalance measurements of diamond growth rates are described. These results can be used to test proposed mechanisms for diamond growth and suggest mechanisms for sp2impurity incorporation. The Thiele modulus is a simple criterion for growth uniformity and is used to compare hot-filament and combustion-assisted growth.

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34

Narayanan, C. M. "Performance and Applications of Semifluidized Bioreactors – A Review." International Journal of Chemical Reactor Engineering 17, no. 1 (July 21, 2018). http://dx.doi.org/10.1515/ijcre-2017-0178.

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AbstractThis paper reviews the design features and performance characteristics of semifluidized bed bioreactors. Both biofilm reactors and immobilized enzyme bioreactors have been analysed. Also, both two phase (liquid – solid) and three phase (gas – liquid – solid) operations are considered. Apart from the hydrodynamic parameters (semifluidization velocity, bed expansion ratio, height of packed section formed, fractional fluid holdups in both fluidized and packed sections), all other operating/system parameters affecting reactor performance such as axial dispersion, intrinsic kinetics of bioconversion (mostly nonlinear), the effectiveness factor and Thiele – type modulus have also been surveyed. The specific advantages and attractive features of these bioreactors have been highlighted based on data from successful case studies such as bioplastic synthesis, biodiesel manufacture, Xanthan gum production and aerobic waste water treatment with and without LPO (Liquid Phase Oxygen) utilization.

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35

Möller, Klaus P., Jonas L. L. Hedlund, Olov Öhrman, and Velaphi Msimang. "The Catalytic Evaluation of Structured Zeolite Catalysts." International Journal of Chemical Reactor Engineering 2, no. 1 (January 20, 2004). http://dx.doi.org/10.2202/1542-6580.1025.

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ZSM-5 films, with thicknesses between 150 and 2300 nm, supported on 3 mm diameter alumina beads are characterised in terms of their catalytic activity and selectivity for tri-isopropylbenzene cracking and para-xylene isomerisation at 450 °C. A reaction-diffusion model adequately represents the experimental data and is used to estimate intrinsic reactivity and diffusion properties of the zeolite films. Results show that the external activity, overall activity and the diffusivity increase with increasing film thickness. The variation in reactivity and diffusivity, when compared to physio-chemical data, are a result of structural defects and non-homogeneities of the zeolite film. The measured diffusivities are within an order of magnitude of those extrapolated from literature. Thick zeolite films have the largest Thiele modulus as the increase in zeolite film thickness dominates over the structural defects. The largest selectivity improvements are observed for thick zeolite films.

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Schwan, Peter, and Klaus P. Möller. "Estimation of Cumene Cracking Reaction-Diffusion Model Parameters: Uniqueness and Parametric Sensitivity Analysis." International Journal of Chemical Reactor Engineering 1, no. 1 (May 16, 2003). http://dx.doi.org/10.2202/1542-6580.1026.

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The pulse response of cumene cracking over ZSM5 extrudates has been measured using a Jetloop recycle reactor. A model assuming first order irreversible reaction with constant macro-pore diffusivity and linear adsorption was used to describe the response curves of the reactants and products. The model parameters adsorption, diffusion and reaction rate are in general highly correlated. Relationships for regions of parameter insensitivity and correlation functions between dependent parameters are given. With the aid of independent measurement of adsorption, a sensitivity analysis and a similarity analysis between equations, it was possible to reduce the 7 parameter model into a 2 parameter model for conditions of strong diffusion limitation observed in these experiments. Although good model fits could be achieved, a high degree of uncertainty in the parameter estimates remained, which reflects the high correlation of the physical parameters. Comparison with steady state results shows that the transient diffusivity for cumene is approximately equal to the Knudsen diffusivity, but an order of magnitude lower than the steady state diffusivity. The transient Thiele modulus for cumene was an order of magnitude higher than the steady state value.

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Narayanan, C. M., Maneka Banik, and Sayani Halder. "Performance Analysis of Immobilized Enzyme Semifluidised Bed Bioreactors." International Journal of Chemical Reactor Engineering 9, no. 1 (December 1, 2011). http://dx.doi.org/10.2202/1542-6580.2670.

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In spite of the many-sided advantages of semifluidised bed bioreactors, no attempt has been made to simulate their performance mathematically. Only scattered experimental data are available in literature. In the present study, therefore, attempts have been made to simulate immobilized enzyme semifluidised bed bioreactors’ performance as equivalent to CSTR – PFR combinations, but with due allowances for the heterogeneity of the system. Bioconversions that follow Michaelis – Menten kinetics (with and without substrate inhibition) and reversible Michaelis – Menten kinetics have been considered. Substrate transfer into the particle (that accommodates the immobilized enzyme) is governed by the magnitude of effectiveness factor which is evaluated based on the generalized integral for the estimation of Thiele – type modulus and the corresponding correlation for effectiveness factor (as a hyperbolic tangent function) and also based on the analytical expression proposed by Gottifredi and Gonzo. Parameters such as operating semifluidisation velocity, porosity of fluidized section, height ratio of packed section to fluidized section are estimated from experimental correlations that are selected through elaborate trial and error procedure. Though the simulation model involves simplifications and empirical estimation of a few parameters, model results are found to exhibit reasonably good agreement with data collected through extensive experimental investigations, the maximum deviation being ±12.5 %. This confirms the acceptability of the software package developed. The developed software could be, therefore, recommended for the design and installation of industrial semifluidised bed bioreactors and also for the performance analysis of existing industrial bioreactors.

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Rivera De la Rosa, Javier, Carlos J. Lucio-Ortiz, Celia D. Pedroza-Solís, David De Haro-Del Rio, and Tomás Hernández García. "La-, Mn- and Fe-Doped Zirconia Washcoats Deposited on Monolithic Reactors via Sol-Gel Method: Characterization and Evaluation of their Mass Transfer Phenomena and Kinetics in Trichloroethylene Combustion." International Journal of Chemical Reactor Engineering 15, no. 5 (July 19, 2017). http://dx.doi.org/10.1515/ijcre-2017-0027.

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Abstract La-, Mn- and Fe-doped ZrO2 was synthesized using the sol-gel method, washcoated on cordierite monoliths and used in trichloroethylene (TCE) combustion. A sol from sol-gel synthesis method was used to obtain the zirconia washcoatings. The washcoatings deposited on the cordierite monolith materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and N2 physisorption measurements, being the crystalline phase determination the most correlate with the catalytic activity. The washcoat properties were correlated to their performance in trichloroethylene combustion. The catalytic washcoatings contained a mixture of crystalline tetragonal ZrO2 and monoclinic ZrO2, and the monoclinic phase exhibited strong interactions with the α-cordierite crystalline phase. For the kinetic tests, the mass transfer into the washcoated monolith channels was evaluated using a recently developed model for the internal mass transfer coefficients for diffusion and reactions in catalytic monoliths. This model involves three resistances. In a plot of the overall resistance as function of the Thiele modulus was determinate that he reaction occurred in the kinetically controlled regime. The kinetic data were fit to two Langmuir–Hinshelwood (LH) models, and the reaction rate was fitted as a function of the trichloroethylene inlet concentration. The adsorption parameters obtained with both LH models were validated based on thermodynamic criteria for the changes in the standard enthalpy of adsorption(${\Delta}H_{ads}^0$) and standard total entropy of adsorption (${\Delta}S_{ads}^0$). It was found that adsorbed TCE and oxygen atoms should be more mobile over the catalyst, which had a higher proportion of tetragonal phase than monoclinic phase of zirconia. The La, Fe-doped catalyst exhibited the highest activity, mainly due the presence of tetragonal zirconia.

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Valdés-Parada, Francisco J., Didier Lasseux, and Stephen Whitaker. "Diffusion and Heterogeneous Reaction in Porous Media: The Macroscale Model Revisited." International Journal of Chemical Reactor Engineering 15, no. 6 (October 24, 2017). http://dx.doi.org/10.1515/ijcre-2017-0151.

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Abstract Diffusion and reaction in porous media have been studied extensively due to the wide range of applications in which this transport phenomenon is involved. In particular, in chemical reactor engineering, reactive mass transfer is crucial to understand the performance of porous catalyst particles immersed in chemical reactors. Due to the disparity of characteristic lengths between the pores and the porous particles, this type of process is usually modeled by means of effective-medium equations, in which the solid and fluid phases are conceived as a pseudo-continuum. For conditions in which the pore-scale Thiele modulus (or Kinetic number) is much smaller than unity, it is reasonable to assume that the effective diffusivity involved in the effective-medium model is only a function of the porous medium geometry. However, a long debate has existed in the literature concerning the extensive use of this assumption for situations in which the Kinetic Number does not satisfy the above mentioned constraint. In addition, the functionality of the effective reaction rate coefficient with the Kinetic number has not been sufficiently studied. In this work we address these issues by means of the volume averaging method. Our analysis is focused on cases in which the Kinetic number can reach values up to 1. Interestingly, for this particular condition, the use of the intrinsic diffusivity tensor is justified. In addition, by means of Maclaurin series expansions, the effective reaction rate coefficient is shown to be acceptably approximated as a first-order function. These two conclusions for the effective medium coefficients constitute the major contributions from this work. In addition, the predictions from the upscaled model are validated by comparison with direct numerical simulations under steady and transient conditions.

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Jiménez-García, Gladys, Roberto Quintana-Solórzano, Ricardo Aguilar-López, and Rafael Maya-Yescas. "Modelling Catalyst Deactivation by External Coke Deposition during Fluid Catalytic Cracking." International Journal of Chemical Reactor Engineering 8, no. 1 (February 18, 2010). http://dx.doi.org/10.2202/1542-6580.2198.

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Although the Fluid Catalytic Cracking (FCC) is an economic important process, simulation of its kinetics is rather empiricalmainly it is a consequence of the complex interactions among operating variables and the complex kinetics that take place. A crucial issue is the inevitable catalyst reversible deactivation, consequence of both, coke (by-product) deposition on the catalyst surface (external) and inside the catalytic zeolite (internal). In order to tackle this problem, two main proposals to evaluate deactivation rate by coking have been extensively applied, both use a probability distribution function called "the negative exponential function"one of them uses the time that catalyst has been in the reacting stream (named Time-on-Stream), and the other is related to the coke amount on/inside the catalyst (denoted as Coke-on-Catalyst). These two deactivation models can be unified by tracking catalyst activity as function of the decrease on effective diffusivity due to pore occlusion (external) by cokethis situation leads to an increase of Thiele modules and consequently a decrease of the effectiveness factor of each reaction. This tracking of catalyst activity incorporates, implicitly, rates of reaction and transport phenomena taking place in the catalyst pores and is therefore phenomenological rather than statistical. In this work, the activity profiles predicted previously are reproduced at MAT laboratory reactor. The same approach is used to model an industrial riser and the results are in agreement with previous reports.

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Journal articles on the topic 'Thiele modulus'

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