Dissertations / Theses on the topic 'Alcohol dehydration'

Solvent recovery is gaining importance in the chemical production processes to reduce the costs and because of environmental concerns. Therefore separation schemes for recovery and recycle of solvents used in printing and packaging industry were developed. However, a low value by-product, mainly ethyl alcohol and isopropanol, is obtained during the solvent recovery process. If the water concentration of this mixture is decreased below 0.1% by weight, the value of it increases significantly. To dehydrate this stream, a pervaporation-adsorption separation scheme is developed in this study. The effect of pervaporation process parameters, such as temperature, feed flow rate, permeate side pressure, feed water and ethyl acetate concentration, on the performance of the PERVAP 2211 and 2201 membranes of Sulzer Chem-tech®
using the real industrial by-product solution obtained from a local company are investigated. Pervaporation tests were conducted using a home made experimental setup equipped with 148 cm2 rectangular shaped membrane module. Permeates obtained from these experiments were analyzed using a gas chromatograph equipped with FID and the water concentration of the feed solutions were analyzed using Karl-Fisher titration. Besides, adsorption studies were conducted using zeolite 3A in a fixed bed column. As a result of this study, PERVAP 2201 membranes showed higher fluxes with a slightly lower permeate water concentration compared to PERVAP 2211 at the at ranges studied. The increase in the pervaporation performance was observed with an increase in the temperature, permeate side vacuum and feed flow rate over the membrane. Therefore, concentrated-mode experiments were conducted at 70°
C, 2 torr permeate side pressure and 1.6 L/min of feed flow rate using the findings of the parametric studies and the retentate of this experiments were further dehydrated using liquid phase adsorption. Finally, the water concentration of the solution was decreased to 0.04% by weight.

Zeolite NaA membranes have attracted special attention in the last years in light of their high selectivities (>40000) and fluxes in the dehydration of alcohol/water mixtures. This Ph.D. thesis is aimed at developing new methods for zeolite NaA membrane synthesis together with the characterization of their mass transfer mechanisms for their further application in membrane reactors.
The membranes have been prepared onto the outer and inner surface of ceramic tubular supports by in situ and seeded hydrothermal synthesis. To avoid the shortcoming of low accessibility to the lumen of the tubes in inner-side membrane synthesis, a new seeding technique is here presented that relies on a controled filtration of a zeolite particle suspension. The seeding weight gain strongly depends on the retentate flow rate, transmembrane pressure and pH. On the other hand, for the hydrothermal syntheses, four different techniques have been used: (1) synthesis in a batch system, (2) synthesis in a centrifugal force field, (3) semi-continuous synthesis and (4) continuous synthesis. The as-synthesized membranes have been characterized by gas permeance, PV of ethanol/water mixtures, XRD and SEM. The results reveal that techniques (3) and (4) that involve gel renewal improve the PV performance, with selectivities and fluxes up to 16000 and 1.2 kg m-2 h-1, respectively, for ethanol/water mixtures 92:8 wt.% at 323 K. Moreover, despite the presence of a certain amount of intercrystalline defects in the layers, their use is suitable for dehydrating long-chain alcohols and ethers, which opens up the possibility of being used in membrane reactors to carry out etherificarion reactions.
The PV process in zeolite NaA membranes has been modeled using the generalized Maxwell-Stefan diffusional theory, including the explicit contribution of intercrystalline porosity and the binary adsorption isotherm of water and ethanol. The surface diffusivities of water obtained from the fittings to PV fluxes are ca. 3-5 orders of magnitud higher than those obtained from adsorption kinetics experiments. This apparent contradiction might be ascribed to the role of grain boundaries between adjacent zeolite grains as fast diffusion paths.
Les membranes zeolítiques hidrofíliques, caracteritzades per les seves elevades relacions Al/Si, constitueixen una camp de recerca prometedor per a la deshidratació de mescles orgàniques mitjançant pervaporació (PV). Més específicament, les membranes de zeolita NaA han rebut especial atenció per les seves altes selectivitats (>40000) y fluxos en la deshidratació de mescles alcohol/aigua. En aquest context, l'objectiu principal d'aquesta tesi doctoral ha estat el desenvolupament de nous mètodes de preparació d'aquestes membranes, juntament amb la caracterització dels seus mecanismes de transport per a la seva posterior aplicació en reactors de membrana.
En els capítols IV i V de la memòria es descriu la preparació de membranes de zeolita NaA sobre suports tubulars ceràmics, tant a la seva superficie externa com interna, mitjançant síntesi hidrotèrmica in situ y creixement secundari. En aquesta configuració, la sembra del suport és complexa a causa de la poca accessibilitat a la seva superficie interior. Per a paliar aquesta limitació, en esta tesi s'ha desenvolupat un mètode de sembra basat en la filtració controlada d'una suspensió de partícules de zeolita NaA. S'ha observat que el guany de de sembra [mg cm-2] depèn fortament del cabal de retingut, pressió transmembranal y pH. D'altra banda, la síntesi hidrotèrmica de les capes s'ha realizat mitjançant quatre tècniques diferents: (1) síntesi en un sistema batch, (2) síntesi sota l'acció d'un camp centrífug, (3) síntesi en un sistema semi-continu i (4) síntesi en un sistema continu. Les capas sintetizades s'han caracteritzat mitjançant permeació de gasos, PV de mescles etanol/aigua, DRX y SEM. Els resultats obtinguts indiquen que la renovació del gel a l'interior dels tubs millora la qualitat pervaporativa de les membranes, amb selectivitats y fluxos de fins a 16000 y 1.2 kg m-2 h-1, respectivament, per a mescles etanol/aigua 92:8 wt.% a 323 K. Les membranes també mostren bones prestacions en la deshidratació d'alcohols primaris C1-C5 i mescles ternàries 1-pentanol/DNPE/aigua. Els resultats també reflecteixen que, a pesar de la presència de defectes en les capes, el seu ús sembla adequat per a deshidratar alcohols y èters de cadena llarga, la qual cosa en possibilitaria l'ús en reactors de membrana per a dur a terme reaccions d'eterficació. Aquesta possibilitat s'il·lustra a partir de la simulació d'un reactor de membrana de zeolita NaA per a la reacció de l'1-pentanol a di-n-pentil éter (DNPE) en fase líquida catalitzada per resines àcides de bescanvi iònic.
En el capítol VI es presenta un model matemàtic per a la predicció de distribucions de tamanys de porus en membranes de MF, UF i NF a partir de la teoria de moments a partir de tres experiments independients: (1) permeació de N2 en règim Knudsen, (2) permeació d'agua pura, i (3) difusió iònica no impedida. Posteriorment, aquest mètode s'ha extès a la caracterització de defectes meso- i macroporosos en capes zeolítiques a partir d'una col·lecció d'experiments de PV. S'observa que les membranes de zeolita NaA perden parcialment la seva capacitat deshidratadora per a porositats intercristal·lines >10-4.
Finalment, en els capítols VII y VIII es descriu la modelització del procés de PV en membranes de zeolita NaA mitjançant la teoria generalitzada de Maxwell-Stefan. La modelització inclou explícitament la contribució de la porositat intercristal·lina i la informació de l'adsorció binària d'aigua i etanol. La modelització de l'equilibri d'adsorció binari s'ha realitzat a partir de la teoria IAST i la versió modificada PRAST. Els models resultants representen satisfactòriament les tendències experimentals. Les difusivitats superficials de l'aigua obtingudes a partir dels ajustos a fluxos de PV són 3-5 ordres de magnitud superiors als obtinguts a partir de cinètiques d'adsorció. Aquesta aparent contradicció s'argumenta a partir de la contribució dels límits de gra en les capes, el quals podrien actuar com a camins de difusió ràpida.

Thesis (MScEng)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Distillation is the most widely used separation technique in the chemical process industry and typically accounts for approximately one-third of the total capital cost and more than half of the total energy consumption of a typical petrochemical-chemical plant. Therefore, the design and optimization of the distillation sequence are of critical importance to the economics of the entire process. Azeotropic mixtures cannot be separated into their pure components via normal distillation. Enhanced distillation techniques such as heterogeneous azeotropic distillation should be considered for these mixtures. Isobaric vapour-liquid-liquid equilibrium (VLLE) data are highly important for the design and analysis of heterogeneous distillation columns. However, limited VLLE data are available in literature due to the difficulties involved with measuring such data. The objective of this work was to systematically evaluate and compare the performance of selected entrainers (including benzene, DIPE and cyclohexane) for the dehydration of C2 and C3 alcohols. To meet this objective, phase equilibrium data had to be measured. Isobaric VLLE at standard atmospheric conditions were measured with a dynamic Guillespie unit equipped with an ultrasonic homogenizer, which prevented liquid-liquid separation. Vapour-liquid equilibrium (VLE) and VLLE data were measured for ethanol/water/di-isopropyl ether (DIPE), n-propanol/water/DIPE and n-propanol/water/isooctane. The VLE data were found to be thermodynamically consistent according to the L-W (Wisniak 1993) and McDermott-Ellis consistency tests. No thermodynamic consistency test, specifically for VLLE data, could be found in literature, but the LLE part of the data followed a regular profile according to the Othmer-Tobias correlation. The binary DIPE/water and isooctane/water azeotropes, as well as ternary ethanol/DIPE/water and n-propanol/isooctane/water azeotropes, as measured in this work, agree well with those found in literature. Regressed parameters for the NRTL, UNIQUAC, and UNIFAC models, generally improved the model predictions compared with built-in Aspen parameters. This confirmed the importance of having actual measured VLLE data available for evaluation and improvement of estimations by thermodynamic models. NRTL predicted the ethanol/DIPE/water and n-propanol/DIPE/water VLLE most accurately. Despite the improved regressed parameters for n-propanol/isooctane/water predictions, the models are still considered unsuitable for accurate prediction of the VLLE behaviour of this system. Separation sequences were simulated in Aspen with built-in and regressed parameters, respectively, to illustrate the significant effect such inaccurate parameters have on these simulations. Phase diagram (VLLE data) evaluation of ethanol and isopropanol (IPA) with various entrainers, as found in literature, indicated that DIPE might be a good entrainer for the dehydration of these alcohols. Benzene and cyclohexane are generally used as entrainers in industry for these processes. Benzene is however carcinogenic and therefore an alternative has to be found (United States Department of Labour - Occupational Safety & Health Administration 2011). Separation sequences were simulated for ethanol dehydration with benzene and DIPE as entrainers, respectively. Taking cost and safety into account, DIPE can be considered an acceptable replacement for benzene as entrainer for ethanol dehydration. A separation sequence was also simulated for the dehydration of IPA with DIPE as entrainer and compared to a simulation with cyclohexane (Arifin, Chien 2007) as entrainer. DIPE was found to be a reasonable alternative to cyclohexane as entrainer for IPA dehydration. Two other separation sequences were simulated as practical examples where DIPE could be used as entrainer for the recovery of ethanol or n-propanol from aqueous Fischer Tropsch waste streams. DIPE is therefore found to be a feasible alternative entrainer to benzene and cyclohexane for the dehydration of ethanol and IPA via heterogeneous azeotropic distillation, based on pre-liminary cost considerations, separation ability and safety. Better entrainers than DIPE may exist, but from the data available in literature and the measurements made in this work DIPE appears to be superior to benzene, cyclohexane and isooctane.
AFRIKAANSE OPSOMMING: Distillasie is die mees algemeen-gebruikte skeidingstegniek in die chemiese proses-industrie. Dit is tipies verantwoordelik vir ʼn derde van die totale kapitaalkoste en meer as die helfte van die totale energie verbruik op ʼn tipiese petrochemiese chemiese aanleg. Daarom is die ontwerp en optimering van ʼn distillasie trein van kardinale belang vir die winsgewendheid van die proses. Azeotropiese mengsels kan nie slegs deur normale distillasie in suiwer komponente geskei word nie. Gevorderde distillasie tegnieke soos heterogene azeotropiese distillasie moet dus oorweeg word vir sulke mengsels. Isobariese damp-vloeistof-vloeistof ewewigsdata is een van die belangrikste fisiese eienskappe vir die ontwerp van heterogene distillasie kolomme. Die hoeveelheid damp-vloeistof-vloeistof ewewigsdata wat beskikbaar is in die literatuur is egter baie beperk omdat dit moeilik is om die data te meet. In hierdie werk is isobariese damp-vloeistof-vloeistof ewewigsdata met ʼn dinamiese Guillespie eenheid, by standaard atmosferiese druk gemeet. Die eenheid is toegerus met ʼn ultrasoniese homogeniseerder om vloeistof-vloeistof skeiding te voorkom. Temperatuur is gemeet met ʼn akkuraatheid van 0.03oC by 0oC. Die sisteem se druk is konstant gehou op 101.3 kPa met ʼn akkuraatheid van 0.35 % VSU (Vol Skaal Uitset). Die ewewigsamestellings is met ʼn relatiewe akkuraatheid van 2 % gemeet. Daar is damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata van etanol/water/di-isopropiel eter (DIPE), npropanol/ water/ DIPE en n-propanol/water/iso-oktaan gemeet. Die damp-vloeistof ewewigsdata is deur die LW (Wisniak 1993) en McDermott-Ellis termodinamiese konsistensie toetse getoets en konsistent bevind. Geen termodinamiese konsistensie toets spesifiek vir damp-vloeistof-vloeistof ewewigsdata kon gevind word nie. Die Othmer-Tobias korrelasie dui egter aan dat die vloeistof-vloeistof ewewig gedeelte van die data ʼn reëlmatige gang volg. Die binêre DIPE/water en iso-oktaan/water azeotrope en ternêre etanol/DIPE/water en n-propanol/iso-oktaan/water fase-ewewigte wat in hierdie werk gemeet is, stem ooreen met die wat in die literatuur te vind is. Die parameters vir die modelle (NRTL, UNIQUAC en UNIFAC) wat in hierdie werk bestudeer is, is in die algemeen verbeter deur regressie van die eksperimentele data. Dit dui daarop dat dit belangrik is om eksperimentele damp-vloeistof-vloeistof ewewigsdata te hê om die voorspellings van termodinamiese modelle mee te evalueer en te verbeter. Die etanol/water/ DIPE en n-propanol/water/DIPE damp-vloeistof-vloeistof ewewigsdata is die akkuraatste deur NRTL voorspel. Ten spyte van die verbeteringe wat deur regressie behaal is met die NRTL en UNIQUAC parameters vir n-propanol/water/isooktaan, word hierdie modelle steeds nie as gepas vir die voorspelling van hierdie datastel beskou nie. Skeidingsreekse is gesimuleer met die ingeboude Aspen parameters en regressie parameters, onderskeidelik, om te illustreer dat onakkurate parameters ʼn beduidende effek op sulke simulasies het. Die evaluasie van fase diagramme van etanol en IPA met verskeie skeidingsagente, wat in die literatuur te vind is, dui aan dat DIPE ʼn goeie skeidingsagent kan wees vir die dehidrasie van hierdie alkohole. Skeidingsreekse vir die dehidrasie van etanol met benseen en DIPE, onderskeidelik, is gesimuleer. Met koste en veiligheid in ag geneem, is daar gevind dat DIPE ʼn aanvaarbare plaasvervanger vir benseen as skeidingsagent vir etanol dehidrasie kan wees. Daar is ook ʼn skeidingsreeks vir die dehidrasie van IPA met DIPE as skeidingsagent gesimuleer en met ʼn simulasie (Arifin, Chien 2007) wat sikloheksaan as skeidingsagent gebruik, vergelyk. Daar is bevind dat DIPE ʼn redelike alternatief vir sikloheksaan kan wees as skeidingsagent vir IPA dehidrasie. Nog twee skeidingsreekse is gesimuleer om as praktiese voorbeelde te dien van die gebruik van DIPE as skeidingsagent om etanol of n-propanol vanaf waterige Fischer-Tropsch afvalstrome te herwin. Daarom is daar bevind dat DIPE ʼn geldige alternatiewe skeidingsagent vir benseen en sikloheksaan is, gebaseer op koste, skeidingsvermoë en veiligheid. Daar kan beter skeidingsagente as DIPE bestaan, maar vanuit die data beskikbaar in literatuur en die metings geneem in hierdie werk, is DIPE die beste.

Thesis (MEng)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The operation and optimisation of a distillation train directly effects the total energy consumption of a typical processing plant. With this in mind, the efficient separation of low molecular weight alcohol azeotropes, using heterogeneous azeotropic distillation, is of great economic and environmental importance. Heterogeneous azeotropic distillation involves the addition of an extraneous component, known as an entrainer, to the mixture to facilitate separation. Benzene has long been replaced as the entrainer of choice, due to its carcinogenic nature, and research into finding a more suitable entrainer has commenced. To determine if an entrainer is suitable for a particular separation, detailed phase behaviour information of the ternary alcohol/entrainer/water system is required; vapour-liquid (VLE), vapour-liquid-liquid (VLLE) equilibria data and the composition of all azeotropes present. This is complicated by the fact that thermodynamic models (like the nonrandom two-liquid (NRTL), universal functional (UNIFAC) and universal quasichemical (UNIQUAC) activity coefficient models) often fail to predict the phase equilibria of ternary systems. The lack of available experimental phase equilibria data, and the inability of thermodynamic models to predict phase equilibria data, has fueled the need for the experimental determination of accurate, repeatable isobaric VLE, VLLE and azeotropic data. With this in mind, this research is focused on the experimental determination of VLE, VLLE and azeotropic data for three low molecular weight alcohol/entrainer/water systems at 101.3 kPa. Following an extensive literature study on azeotropes, applicable separation techniques and available VLE and VLLE data in literature, the ethanol/2-butanone/water, n-propanol/2-butanone/water and iso-propanol/2-butanone/water systems were chosen for experimental investigation. The experimental determination was carried out in a Gillespie type still, equipped with an ultrasonic homogenizer. The temperature and pressure accuracies of the equipment were found to be 0.03°C and 2mbar respectively. The chosen experimental methodology was verified, and its repeatability tested, through the measurement of isobaric VLE and VLLE data of ethanol/isooctane, ethanol/n-butanol/water and n-propanol/isooctane/water systems at 101.3 kPa and subsequent comparison of the measured data with literature data. The compositional error reported, taking into account experimental and analysis effects, is ±0.014 mole fraction. All experimentally determined data sets, verification and new data, were tested for thermodynamic consistency by using the Wisniak modification of the Herrington test, the L/W consistency test, as well as the McDermott-Ellis consistency test, and found to be consistent. The Othmer-Tobias correlation was used to ensure the measured LLE data followed a steady trend, with all R-values larger than 0.910. For all three of the new systems chosen, the absence of ternary heterogeneous azeotropes was noted. The presence of a ternary homogeneous azeotrope was found for both the ethanol/2-butanone/water and iso-propanol/2-butanone/water systems. No ternary azeotropes are present for the n-propanol/2-butanone/water system. Suitable entrainers were compared to 2-butanone (MEK) by plotting measured data and literature information of five similar alcohol/entrainer/water systems on a ternary phase diagram. It was found that MEK could not be considered as a suitable entrainer for heterogeneous azeotropic distillation of ethanol, n-propanol and IPA. This is due to the absence of a ternary heterogeneous azeotrope for the aforementioned alcohol/MEK/water systems. Finally, the ability of thermodynamic models (NRTL, UNIFAC and UNIQUAC) to predict experimental data was determined both visually and through descriptive statistics. This entailed the inspection of ternary phase diagrams and the calculation and evaluation of average absolute deviation (AAD) and and average absolute relative deviation (AARD%) values. The measured data were modelled in Aspen Plus®. It was found that none of the models could predict the ternary systems with acceptable accuracy and the data were regressed. In general, the regressed parameters for the NRTL, UNIFAC and UNIQAC models improved the model predictions when compared to the built-in Aspen parameters. The UNIFAC model predicted the ethanol/MEK/water and n-propanol/MEK/water systems most accurately while none of the models could predict the IPA/MEK/water systems with acceptable accuracy.
AFRIKAANSE OPSOMMING: Die ontwerp en optimering van 'n distillasietrein het ‘n duidelike effek op die totale energieverbruik van ‘n tipiese prosesaanleg. Met dit in gedagte, is ‘n meer doeltreffende skeiding van lae molekulêre massa alkohol aseotrope, met behulp van heterogene aseotropiese distillasie, voordelig vir die ekonomie en die omgewing. Heterogene aseotropiese distillasie behels die toevoeging van 'n eksterne komponent, wat bekend staan as 'n skeidingsagent, om uiteindelik die skeiding te fasiliteer deur die komponente se dampdrukke te verander. Benseen was in die verlede ‘n gewilde skeidingsagent, maar dit is a.g.v. sy karsenogeniese eienskappe nie meer aanvaarbaar om te gebruik nie. Nuwe navorsing in hierdie veld fokus dus onder andere op die identifisering van meer geskikte skeidingsagente. Om te bepaal of 'n skeidingsagent geskik is, word indiepte fasegedrag inligting benodig, i.e. damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata en die samestelling van alle aseotrope teenwoordig. Ongelukkig kan termodinamiese modelle dikwels nie die fasegedrag van ternêre stelsels voorspel nie. Dit, sowel as die beperkte beskikbaarheid van eksperimentele ewewigsdata in die literatuur, het dus hierdie navorsing aangevuur. Die projek het gefokus op die experimentele bepaling van damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata en aseotropiese data vir drie alkohol/skeidingsagent/water-stelsels by 101.3 kPa. Na ‘n indiepte literatuurstudie van aseotrope, gepaste skeidingstegnieke en beskikbare damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata, is 2-butanone (MEK) gekies as ‘n moontlike skeidingsagent en die etanol/MEK/water-, n-propanol/MEK/water- en iso-propanol/MEK/water-stelsels gekies vir eksperimentele ondersoek. Die data is met ‘n dinamiese Gillespie eenheid gemeet, toegerus met ‘n ultrasoniese homogeniseerder om vloeistof-vloeistof skeiding te voorkom. Die akkuraatheidsbande van temperatuur- en druk meetinstrumente was 0,03°C en 2 mbar, onderskeidelik. Die eksperimentele metode en die herhaalbaarheid van metings is bevesting, deur die isobariese damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata van etanol/iso-oktaan, etanol/n-butanol/water en n-propanol/iso-oktaan/water te vergelyk met onafhanklike stelle ooreenstemmende data uit die literatuur. Die gesamentlike eksperimentele en analitiese fout wat gemaak kon word tydens bepaling van molfraksie samestellings was ±0.014 molfraksie. Alle gemete eksperimentele data is getoets vir termodinamiese samehang deur middel van beide die L/W en McDermott-Ellis konsekwentheidstoetse. Die Othmer-Tobias korrelasie is gebruik om seker te maak dat die gemete LLE data ‘n konstante tendens volg, met alle R-waardes groter as 0.910. Vir al drie van die nuwe stelsels wat gekies is, was ‘n drieledige heterogene aseotroop afwesig. Die teenwoordigheid van drieledige homogene aseotrope is egter waargeneem vir die etanol/MEK/water- en IPA/MEK/water-stelsels. Geen drieledige aseotrope is vir die n-propanol/MEK/water-sisteem gevind nie. Alle gemete data, asook literatuur inligting van vyf soortgelyke alkohol/skeidingsagent/water sisteme, is op ‘n drieledige fase diagram voorgestel om die skeidingsagente met mekaar te vergelyk. Hiervolgens word dit getoon dat MEK nie as ‘n gepaste skeidingsagent vir heterogene aseotropiese distillase beskou kan word nie a.g.v. die afwesigheid van ‘n drieledige heterogene aseotroop in die voorgenoemde alkohol/MEK/waterstelsels. Die vermoë van die termodinamiese modelle (NRTL, UNIFAC en UNIQUAC) om die eksperimentele data te voorspel is visueel (per grafiek) sowel as deur beskrywende statistiek bepaal. Dit behels die inspeksie van drieledige fasediagrame en die berekening en evaluasie van die gemiddelde absolute afwyking en gemiddelde absolute relatiewe afwykingswaardes. Hierdie teoretiese data is met Aspen Plus® bepaal. Nie een van die modelle kon die drieledige stelsels se fasegedrag met aanvaarbare akkuraatheid voorspel nie. Die parameters vir die NRTL-,UNIFAC- en UNIQUAC-modelle kan verbeter word deur middel van regressie, in vergelyking met die ingeboude Aspen parameters. Dit is bevind dat die UNIFAC model die etanol/MEK/water- en n-propanol/MEK/water-stelsel die beste kan voorspel. Nie een van die bogenoemde modelle kon egter die fasegedrag van die IPA/MEK/water-stelsel voorspel nie.

Orientador : Maria Aparecida Silva
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Na secagem de determinados alimentos como frutas, juntamente com a água há também a evaporação de outras substâncias voláteis presentes em quantidades menores. Quando essas substâncias possuem características odoríferas, a qualidade do produto final seco pode ser prejudicada devido à diminuição do aroma. Por isso, torna-se interessante considerar nos estudos de secagem a evaporação, além da água, desses outros componentes voláteis. A modificação da atmosfera tem sido utilizada somente em armazenamento, principalmente de vegetais, mas pode também ser estendida à secagem, pois pode influenciar a perda de voláteis responsáveis pelas características sensoriais do produto final. No presente trabalho, desenvolveu-se um sistema de secagem, no qual a atmosfera de secagem pode ser modificada pela adição de gases ou líquidos. O referido sistema é composto por um túnel de secagem, feito de paredes de policarbonato e de um sistema de aquisição e controle de dados, onde se pode acompanhar continuamente o peso da amostra e controlar a temperatura do gás de secagem. As amostras submetidas à secagem foram um sistemamodelo e o abacaxi (Smooth Cayenne). O primeiro foi desenvolvido a partir da composição química básica do abacaxi e da adição de outros compostos, contendo um dos principais componentes do aroma desta fruta (hexanoato de etila). A atmosfera de secagem foi modificada pela adição de etanol (0,5% v/v) ao ar por meio de um bico atomizador, localizado na parte superior do túnel de secagem. Nos experimentos de secagem (temperatura: 40 e 60ºC; velocidade do gás de secagem: 0,42 e 0,84 m/s; umidade relativa do gás de secagem: 8 e 23%), acompanhou-se a variação do teor de água com o tempo e a variação do teor dos componentes do aroma, sendo estes últimos determinados por cromatografia gasosa. Desenvolveu-se a metodologia analítica de determinação do aroma em ambos os sistemas, a partir dos estudos de extração de aromas e de análise cromatográfica gasosa. O aroma presente no sistema-modelo foi extraído em hexano e os componentes voláteis do aroma do abacaxi foram extraídos em éter etílico. A modificação da atmosfera de secagem do sistema-modelo com etanol, promoveu uma evaporação menos intensa de água e do componente do aroma. Já nos experimentos de secagem de abacaxi, aparentemente a evaporação do aroma foi mais intensa em atmosfera modificada do que em atmosfera normal
Abstract: In the drying of some foods such as fruits, along with water removal there is also the evaporation of other volatile substances present in lesser amounts. When these substances possess odoriferous characteristics, the quality of the final dried product can be lowered due to aroma loss. Therefore, it is interesting to consider in the drying studies the evaporation of these volatile components other than water. The modification of atmosphere has been used only in storage, especially for vegetables, but can be extended to drying since it can influence the loss of volatile components responsible for the sensorial characteristics of the final product. In the present work, a drying equipment was developed, in which the drying atmosphere can be modified by the addition of gases or liquids. The equipment is composed of a drying tunnel with polycarbonate walls and a data acquisition and control system, allowing continuous monitoring of the sample weight and control of the drying gas temperature. Samples submitted to drying were a model-system and pineapple (Smooth Cayenne). The model-system was developed from the basic chemical composition of pineapple and the addition of other compounds, containing one of the main aroma components (ethyl hexanoate). The drying atmosphere was modified by the addition of ethanol (0,5% v/v) to air using a double-fluid atomizer, which is located in the upper part of the drying tunnel. In the experiments, the variation with time of water content and aroma components concentration, were monitored. The latter was measured by gas chromatography. An analytical methodology for determination of the aroma components in both systems was developed from the studies of aroma extraction and gas chromatography. The aroma present in the model-system was extracted with hexane and the volatile aroma components from the pineapple were extracted with ethylic ether. The modification of the atmosphere with ethanol in drying of the model-system promoted a less intense evaporation of both water and aroma component. In the experiments of pineapple drying, apparently the evaporation of aroma was more intense in modified atmosphere than in normal atmosphere
Doutorado
Engenharia de Processos
Doutor em Engenharia Química

Di-n-butyl ether (DNBE) is considered a very attractive oxygenate compound to reformulate diesel fuel. The research work performed along this thesis has clearly proven that sulfonic P(S-DVB) ion exchange resins are suitable catalysts for the synthesis of DNBE from the liquid phase dehydration of 1-butanol at the temperature range of 140-190 °C. A catalyst screening of acidic P(S-DVB) ion exchange resins showed that resins activity is enhanced with high acid capacities and with polymer matrices that are able to swell moderately allowing 1-butanol ready access to the active sites but without resulting in very large distance between the active centers. The resin Amberlyst 36 (oversulfonated, medium values of %DVB) proved to be the most active catalysts tested. However, in an industrial process a high selectivity to DNBE is extremely desirable from an environmental and economic standpoint, and resins that present a more elastic polymer matrix and higher ability to swell (gel type resins and Amberlyst 70) are the ones that present higher selectivities. Among all the tested resins, Amberlyst 70 was selected as the most suitable catalyst for industrial use given its excellent property balance: satisfactory activity, high selectivity to DNBE and thermal stability up to 463 K. The relatively large value found for the thermodynamic equilibrium constant of DNBE formation and the fact that the formation of the secondary product 1-butene was extremely slow assure high conversion levels in an industrial etherification process. DNBE formation proved to be a slightly exothermic reaction, almost athermic, whereas 1-butene formation was found to be an endothermic reaction. A comprehensive kinetic analysis enlightened that the reaction rate to form DNBE on Amberlyst 70 is highly influenced by the temperature and the presence of water. Two kinetic models that are able to predict the reaction rates of DNBE formation were identified. One of them stems from a Langmuir-Hinshelwood-Hougen-Watson (LHHW) formalism in which two adsorbed molecules of 1-butanol react to yield ether and water, being the reversible surface reaction the rate limiting step. The other one stems from a mechanism in which the rate limiting step is the desorption of water and where the adsorption of DNBE is negligible. Both models present several characteristics in common: in both water inhibition effect is correctly represented by a correction factor derived from a Freundlich adsorption isotherm; the number of free active sites is found to be negligible compared to the occupied ones; both present similar values of apparent activation energies (122 ± 2 kJ/mol). The study of the influence of typical 1-butanol impurities (isobutanol or ethanol and acetone, depending on the production process) demonstrated that isobutanol enhances the formation of branched ethers whereas ethanol leads to the formation of ethyl butyl ether and di- ethyl ether and acetone hardly reacts. In the second part of this thesis, it was demonstrated the suitability of molecular dynamics simulations in the understanding of the microscopic structure of P(S-DVB) ion-exchange resins and the prediction of their properties. Atomistic simulations of the structure of sulfonated P(S-DVB) resins reveled the decisive role that internal loops (closed polymer chains) play in defining the properties (i.e. density, porosity and structures) of highly cross-linked resins. Thus, although crosslinks ensure the local backbone structure, internal loops confer rigidity and loop architecture. It was also demonstrated that the developed atomistic model is able to predict the swelling behavior of ion-exchange resins in 1-butanol. From the swelling study performed by means of molecular dynamic simulation it was possible to characterize and quantify the structure of the swollen polymeric network at molecular level and to conclude that alcohol molecules tend to interact with the sulfonic groups of the resin.

Solid acid catalysts were prepared through silicon substitution into aluminophosphate frameworks. Silicon incorporation was confirmed using solid state nuclear magnetic resonance spectroscopy. The nature of the acid sites generated was determined using Fourier Transform infrared spectroscopy. These materials were tested as catalysts for the dehydration of ethanol to ethylene at low operating temperatures. The materials were active for dehydration of ethanol to ethylene with significant differences observed between aluminophosphate frameworks both in terms of selectivity to the desired product but also in terms of the nature of the silicon substitution and the active sites. Links have been made between these properties and the observed catalytic behaviour. The effect of the catalytic framework is further explored though the testing of cobalt substituted aluminophosphates for ethanol dehydration. Silicon substituted aluminophosphates have been tested for the dehydration of 1-phenylethanol to styrene as an example of catalysis in the liquid phase. Here the influence of framework was particularly significant due to the large substrate. The effect of redox metals in the aluminophosphate framework has been investigated through the use of calcined and pre-reduced cobalt substituted aluminophosphates for the dehydration of ethanol to ethylene. Analysis of the catalytic product stream was combined with UV-Visible measurements to investigate potential redox processes occurring during the reaction time on stream and the influence of the oxidation state of the redox metal on the catalytic products of the reaction.

Une nouvelle famille de catalyseurs a été développée pour la déshydratation des alcools en C2-C4. Ces catalyseurs qui correspondent à des phosphates de terres rares, sont plus actifs et au moins aussi sélectifs que les catalyseurs traditionnels de déshydratation et ils ne montrent que des désactivations limitées en fonction du temps par dépôt de coke à leur surface. Plusieurs méthodes de préparation de ces catalyseurs ont été développées et les catalyseurs ont été caractérisés par DRX, spectroscopie IR, Raman, MET, EDX, XPS. L’acido-basicité des catalyseurs a été étudiée par TPD de NH3 et CO2 et adsorption de pyridine et de lutidine suivie par IR. Les études catalytiques ont permis de montrer que le mécanisme principal de déshydratation est de type E1 et que les principaux sites catalytiques sont des sites acides de Bronsted ou de Lewis. Les sites acides de Bronsted correspondent à des d’espèces (H2PO4)2- dont la présence est liée à un excès de phosphore en surface, les sites acides de Lewis correspondent aux ions terre rare. L’implication des deux types de sites a été étudiée en fonction de plusieurs paramètres. Les performances des catalyseurs ont été attribuées à une quantité importante de sites acides moyennement forts et à une très faible quantité de sites basiques faibles. Dans la déshydratation du 1-butanol, il apparaît clairement que les sites les plus actifs et les plus sélectifs en 2-butene sont des sites acides de Bronsted. Sur un plan plus appliqué la thèse a permis de mettre au point de nouveaux procédés de préparation de propène soit direct soit passant par une étape de métathèse (éthylène + 2-butène), de 1 et 2- butène et de butadiène (déshydratation du 3-butène-1-ol et du 2, 3-butanediol)
A new family of catalysts has been developed for the dehydration of C2-C5 alcohols. These performing catalysts, which correspond to lanthanides phosphates, are more active and at least as selective when compared to traditional efficient dehydration and show very limited deactivation under reaction flow due to coke deposition. Different methods of preparation of the catalysts have been developed and the catalysts have been characterized by various techniques like XRD, Raman spectroscopy, TEM with EDX analyses and XPS. The acid base properties of the solids have been studied by NH3 and CO2 TPD and by adsorption of lutidine and pyridine followed by IR. The catalytic studies allow showing that the main reaction mechanism on the solids was E1-type and the active sites are both Bronsted and Lewis sites. The Bronsted acid sites correspond to (H2PO4)2- species which presence is related to an excess of P at the surface and the Lewis acid sites correspond to the rare earth cations. The implication of both types of sites as a function of different parameters has been studied. The high efficiency has been attributed to a high amount of acid sites with a moderated acid strength and to a very low amount of basic sites with weak strength. In the dehydration of 1-butanol it appears clearly that the more active and selective sites are Brosnted acid sites. On an industrial point of view the, the thesis work allowed to design new processes of production of propene either direct or through a metathesis reaction (ethylene+ 2-butene), of 1 and 2-butene and of butadiene (dehydration of 3-butene-1-ol and 2, 3-butanediol

碩士
國立臺灣科技大學
化學工程系
96
The design and control of dehydration of isopropyl alcohol (IPA) via heterogeneous and homogeneous (extractive distillation) azeotropic distillation will be investigated in this thesis. For heterogeneous azeotropic distillation, Chien et al. (Ind. Eng. Chem. Res. 2004, 43, 2160) has been studied the design and control of a heterogeneous azeotropic distillation column of isopropyl alcohol using cyclohexane (CyH) as entrainer with feed composition to the heterogeneous azeotropic column assuming to be near the isopropyl alcohol (IPA) and water azeotropic composition (water at 31 mol % in that paper). However, for a typical waste IPA stream, it is more diluted. Taking a typical waste IPA stream with equal molar of IPA and water as an example in this study, design and control of this system will be investigated. The resulting proposed design flow sheet is a two-column system which combines pre-concentrator column and recovery column into a single column. This design adapted from Ryan and Doherty (AIChE J. 1989, 35, 1592) for their ethanol dehydration process not only minimizes the total annual cost but also is very robust when operating in the face of various fresh feed disturbances. Only one tray temperature control loop in the heterogeneous azeotropic column and another one in the combined pre-concentrator/recovery column are needed in the proposed overall control strategy. For homogeneous extractive distillation, dimethyl sulfoxide (DMSO) is used as heavy entrainer. The design flowsheet includes an extractive distillation column and an entrainer recovery column. The optimal design flowsheet of this complete process has been established showing that the total annual cost and the needed steam cost of this design flowsheet is significantly less than the competing design flowsheet via heterogeneous azeotropic distillation. A very simple overall control strategy has also been proposed which requires only one tray temperature control loop in each column to hold the high-purity specifications of the two products. Dynamic simulations reveal that fixing of the reflux ratio is not a suitable control strategy. Instead, the strategy to fix the two reflux flow rates should be used to reject feed disturbances.

Pervaporation (PV), a non-porous membrane separation process, is gaining considerable attention for solvent separation in a variety of industries ranging from chemical to food and pharmaceutical to petrochemicals. The most successful application has been the dehydration of organic liquids, for which hydrophilic membranes are used. However, during pervaporation, excessive affinity of water towards hydrophilic membranes leads to undesirable swelling (water absorption) of the membrane matrix. To control swelling, often hydrophilic membranes are crosslinked to modify physicochemical (surface and bulk) properties. Since the transport of species in pervaporation is governed by sorption (affected by surface and bulk properties) and diffusion (affected by bulk properties), it is essential to study the effect of crosslinking on the surface and bulk physicochemical properties and their effects on separation performance. This thesis focuses on the effect of crosslinking on the physicochemical properties (e.g., crystallinity, hydrophilicity, surface roughness) of hydrophilic polymeric membranes and their dehydration performance alcohol-water mixtures. Poly(vinyl alcohol), PVA was used as the base polymer to prepare membranes with various morphologies such as homogeneous, blended (with Chitosan, CS) and composite (with poly(sulfone), PSf) structures. Before applying the crosslinked membranes for the PV dehydration of alcohols, the physicochemical characterization were carried out using Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), tensile testing, contact angle and swelling experiments. The crosslinked membranes showed an increase in surface hydrophobicity from the contact angle measurements as compared to the uncrosslinked membranes. AFM surface topography showed that the membrane surfaces have nodular structures and are rough at the nanometer scale and affected by the crosslinking conditions such as concentration and reaction time. Surface hydrophobicity and roughness was found to increase with increasing degree of crosslinking. DSC measurements showed an increase in melting temperature of the polymer membranes after crosslinking. For the PV dehydration of ethanol, a decrease in flux and an increase in selectivity were observed with increase in the degree of crosslinking. Effects of membrane thickness (of PVA layer) for crosslinked PVA-PSf composite membranes were studied on PV dehydration of ethanol. Total flux and selectivity were statistically analyzed as a function of the membrane thickness. In general, the outcome agrees with the solution-diffusion (S-D) theory: the total flux was found to be significantly affected by the PVA layer thickness, while the selectivity remains nearly unaffected. Using the S-D theory, the mass transfer resistance of the selective layers was calculated and found to increase with thickness. The relatively small change observed for selectivity has been related to the crosslinking of the PVA layer that increases the surface hydrophobicity of the membrane. Chitosan-Poly(vinyl alcohol), or CS-PVA, blended membranes were prepared by varying the blending ratio to control membrane crystallinity and its effect on the PV dehydration of ethylene glycol. The blended membranes were crosslinked interfacially with trimesoyl chloride (TMC)/hexane. The crystallinity of the membrane was found to decrease with increasing CS wt% in the blend. Although the crosslinked CS-PVA blend membranes showed improved mechanical strength, they became less flexible as detected in tensile testing. The resulting crosslinked CS-PVA blended membranes showed high flux and selectivity simultaneously, for 70-80wt% CS in the blend. The effect of feed flow-rate was studied to find the presence of concentration polarization for 90wt% EG in feed mixture as well. The crosslinked blend membrane with 75wt% CS showed a highest total flux of 0.46 kg/m2/h and highest selectivity of 663 when operating at 70oC with 90wt% EG in the feed mixture. Effects of crosslinking concentration and reaction time of trimesoyl chloride (TMC) were studied on poly(vinyl alcohol)-poly(sulfone) or PVA-PSf composite membranes. Results showed a consistent trend of changes in the physicochemical properties: the degree of crosslinking, crystallinity, surface roughness, hydrophilicity and swelling degree all decrease with increasing crosslinking agent (TMC) concentration and reaction time. The crosslinked membrane performance was assessed with PV dehydration of ethylene glycol-water mixtures at a range of concentrations (30 to 90wt% EG). The total flux of permeation was found to decrease, while the selectivity to increase, with increasing TMC concentration and reaction time. The decrease in flux was most prominent at low EG concentrations in the feed mixtures. A central composite rotatable design (CCRD) of response surface methodology was used to analyze PV dehydration performance of crosslinked poly(vinyl alcohol) (PVA) membranes. Regression models were developed for the flux and selectivity as a function of operating conditions such as, temperature, feed alcohol concentration, and flow-rate. Dehydration experiments were performed on two different alcohol-water systems: isopropanol-water (IPA-water) and ethanol-water (Et-water) mixtures around the azeotrope concentrations. Judged by the lack-of-fit criterion, the analysis of variance (ANOVA) showed the regression model to be adequate. The predicted flux and selectivity from the regression models were presented in 3-D surface plots over the whole ranges of operating variables. For both alcohol-water systems, quadratic effect of temperature and feed alcohol concentration showed significant (p < 0.0001) influence on the flux and selectivity. A strong interaction effect of temperature and concentration was observed on the selectivity for the Et-water system. For the dehydration of azeotropic IPA-water mixture (87.5wt% IPA), the optimized dehydration variables were found to be 50.5oC and 93.7 L/hr for temperature and flow-rate, respectively. On the other hand for azeotropic Et-water mixture (95.5wt% Et), the optimized temperature and flow-rate were found to be 57oC and 89.2 L/hr, respectively. Compared with experiments performed at optimized temperature and feed flow-rate, the predicted flux and selectivity of the azeotropic mixtures showed errors to be within 3-6 %.

碩士
中原大學
化學工程研究所
98
In this study, a series of PA/ PAN composite hollow fiber membranes (HFMs) was prepared by the interfacial polymerization of various water-soluble amine monomers 1,6 hexanediamine (HDA), ethylenediamine (EDA), diethylenetriamine (DETA), and tetraethylenepentamine (TEPA) and oil-soluble monomer trimesoyl chloride (TMC) to investigate the effects of functional groups and structural patterns of the monomers on the pervaporation performance of the PA/PAN composite hollow fiber membranes for separating aqueous alcohol solutions. When water-soluble monomer had more amine functional groups, the PA/ PAN composite hollow fiber membrane exhibited superior pervaporaion performance. As identified by XPS, results indicated that the more the amine functional groups, the higher degree of cross-linking in the polymerized composite hollow fiber membrane . From light transmission experiments, it was found that the more the amine functional groups, the faster the free-standing membrane interfacial polymerization reaction rate. As a result of the positron measurements, it was found that the more the amine functional groups, the lower the S parameter values and the smaller the polymer free volume, which can also explain the higher degree of cross-linking. From the results obtained by means of AFM, SEM, XPS, water contact angle measurement, and light transmission, we found that the more the water-soluble monomer amine functional groups, the faster the interfacial polymerization reaction rate and the higher the degree of cross-linking on the polyamide surface, resulted from more hydrophilic. Furthermore, from positron results, it was found that the more the amine functional groups, the smaller the free volume amount. The above results and the pervaporation performance experimental results were correspond with each other. The ideal interfacial polymerization conditions for PAN hydrolysis time with NaOH, TEPA concentration, TEPA soaking time, TMC concentration and reaction time were 30min, 2wt%, 1min, 1wt% and 30sec, respectively. In a pervaporation performance test at 25 C for separating 90 wt% ethanol, the permeation flux was 342 g/m2h and the concentration of water in the permeate was 97.5 wt%. To further improve the pervaporation performance of PA/mPAN composite hollow fiber membrane, silica was added in the PAN hollow fiber membrane, and with this addition, it was expected to increase membrane’s hydrophilicity and the pore size of the outer surface. SEM and AFM were the instruments used to observe the morphologies and the roughness of the silica/PAN hollow fiber membrane, and scanning electron microscope energy-dispersive x-ray spectroscopy (SEM-EDX) was used to observe the distribution of silica in hollow fiber membrane. It was found that silica was distributed well on the outer surface of the hollow fiber membrane. With an increase in the content of silica, the roughness decreased. From the water contact angle measurement, it was revealed that with an increase in the silica content, the hydrophilicity of the hollow fiber membrane increased. Pure water permeation test was carried out, and the finding was that as the content of silica increased, the pure water flux increased first and then decreased gradually. The 5 wt% silica added PAN hollow fiber membrane was chosen to prepare the PA/silica-mPAN composite hollow fiber membrane through interfacial polymerization. However, the pervaporation performance results showed that there was no improvement. Therefore, we changed the interfacial polymerization process, we did not carry out the hydrolysis process for PAN hollow fiber membrane. As a result, the PA/silica-PAN composite membrane exhibited better pervaporation performance. The pervaporation separation of 90 wt% aqueous ethanol solution at 25 C using the PA/silica-PAN composite hollow fiber membrane gave a permeation rate and a water concentration in the permeate of 479 g/m2h and 99 wt%, respectively.

MÁSTER UNIVERSITARIO EN INGENIERÍA QUÍMICA POR LA UNIVERSIDAD DE CANTABRIA Y LA UNIVERSIDAD DEL PAÍS VASCO/EUSKAL HERRIKO UNIBERTSITATEA
Tese arquivada ao abrigo da Portaria nº 227/2017 de 25 julho.
Zeolite membranes are attracting attention as alternative separation technologies to conventional distillation especially for separation of close-boiling mixtures. In addition, zeolite membranes can also be integrated in membrane reactors. A few types of zeolite membranes, such as A-type and T-type, have been commercialized and applied in the industry for dehydration of solvents. However, applications of A-type and T-type membranes are limited due to their poor stability in acidic media and water-rich systems. To overcome these limitations, hydrophilic ZSM-5 zeolite membranes have been developed, although their long-term performance, the mass transport mechanism and the micro-structure of the membrane are still far from full understanding. Therefore, the main objective of this master thesis was to study the performance of the synthesized ZSM-5 membranes in long-term pervaporation experiments, considering alcohol dehydration processes as application. The separation performance was studied considering different types of alcohol and composition of their aqueous mixtures. The post-treatment of the membrane was also investigated to recover the membrane performance. Lastly, molecular simulations of competitive adsorption of water and alcohol molecules on ZSM-5 zeolitic pores using grand canonical ensemble molecular dynamics were studied. By comparing the information obtained by experiments to the results of the molecular simulations, the membrane micro-structure and the transport mechanism were discussed. This master thesis has been carried out in the Green Chemical Processes laboratory from the division of Membrane Science and Engineering in Yamaguchi University (Japan), headed by Prof. Izumi Kumakiri, in the framework of a bilateral agreement for academic and research exchange with the Environmental Technologies and Bioprocesses Research group of the University of Cantabria (Spain) leaded by Prof. Ane Urtiaga. The research group of Professor Kumakiri is expert in the development of inorganic membranes, in particular zeolite membranes, and their knowledge has been combined with the expertise of Professor Urtiaga in the industrial application of pervaporation for solvent dehydration.

碩士
國立成功大學
化學系碩博士班
92
This study focus on the application of pervaporation on dehydration of solvents, and also aided esterification reaction .The membrane used for this study is PVA/PAN cross-linked with maleic acid. The dehydration of solvents included ethanol, isopropanol and butanol aqueous mixtures. Afterwards, pervaporation aided esterification to react ethyl acetate and butyl acetate, determine the effect of separation of water on the esterification reaction. We also use SEM, FT-IR, TGA to analyze the membrane surface’s structure chemical structure and thermal stability of the membrane. 　　On dehydration of aqueous solvent mixtures, the water content in the feed mixtures, temperature reaction, the size of organic solvent will affect the selectivity and flux of the membrane. From the experimental results, we find that the selectivity of ethanol is approximately 20~191, the flux is about 0.03~1.25 kg/m2hr ; the selectivity of isopropanol is about 115~4500，the flux is 0.06~0.84 kg/m2hr ; the selectivity of n-butanol is about 314~2167，the flux is 0.12~0.60 kg/m2hr。Value of activation energy of B3 membrane on dehydration of organic solvent in sequence：n-butanol < isopropanol < ethanol。 　　Furthermore, we also discuss the effect of pervaporation on esterification。The experimental results show that the membrane has a high selectivity on water。Water flux has occupied over 70% of the total flux。Since almost all of the water left the feed side, therefore pervaporation can increase the conversion of reaction。

碩士
國立臺灣科技大學
化學工程系
90
Abstract In various chemical processes, we often need to separate acetic acid-water system or isopropyl alcohol-water system. This research is to study these two important heterogeneous azeotropic separation process. We simulate the system of dehydration of acetic acid in different decanter organic level control strategies and improve the ability of eliminating disturbance. Another dehydration of isopropyl alcohol process, we compare two-column and three-column structures to further purity the top product of the heterogeneous azeotropic column in Chien et al.(1999). After the steady state simulations of two structures, the optimum process designs and operating conditions will be given. The most economical structure for this separation will be recommended. Dynamic simulations of various control strategies for the overall process will be compared.

博士
東海大學
化學工程與材料工程學系
101
Because the reflux ratio used either in the pre-concentration column or the recovery column of the three-column heterogeneous distillation sequence for IPA dehydration system is quite small demonstrated by Arifin and Chien (2007), these two conventional distillation columns are both replaced by a stripping column in this study and a new separation scheme called Scheme 3 is thereby developed. The economic analysis of the proposed system shows it is more energy efficient and lower capital costs as compared to the two and three-column sequences afore-mentioned. Further, in developing a plant-wide control structure, a tray temperature control loop is implemented in each of the three columns which regulates reboiler duty in order to maintain the bottom product compositions for Scheme 3, and ratio control of the organic reflux flow to the feed flow rate of the azeotropic column is used to reject feed rate disturbance. Closed-loop responses to ±20% changes in fresh feed rate and feed H2O composition show that the proposed strategy has good control performance. This proposed scheme can be achieved three goals that are more energy saving, less total annual cost, and process easily controlled.

碩士
中原大學
化學工程研究所
105
In this study, meso-/microporous AlBTC MOA (metal-organic aerogel) were synthesized via the sol-gel process. Its gelation mechanism was discussed by changing its reaction temperature and the concentration of AlBTC sol. Then as-synthesized particles were successfully incorporated into the chitosan polymeric solution to form mixed matrix membranes (MMMs) and used to dehydrate 90 wt% butanol/water mixture under 25oC in a pervaporation process. The as-prepared MMMs showed a good pervaporation performance on separating butanol/water. Because the meso-/microporous in AlBTC MOA provides more channels to permeate the feed, and the hydrophilicity of AlBTC MOA enhances the separation factor. However, when too much particles doped, the aggregation were occurred and formed unselective pores in the membrane, causing the pervaporation efficiency to reduce. As a result, we found the AlBTC/CS MMMs with 0.3 wt% AlBTC-0.075 doped had the best pervaporation performance. Its flux, separation factor, and pervaporation separation index (PSI) are 1233 g/m2h, 1574, 1941 Kg/m2h respectively. Moreover, when 0.25 g glutaraldehyde crosslinking is added AlBTC-0.075/CS MMMs obtains an even better performance. Its flux, separation factor, and PSI are 526 g/m2h, 4578, 2410 Kg/m2h respectively. Summarizing the above, the AlBTC/CS MMMs broke the trade-off between the flux and the separation factor, therefore, the MMMs has high flux and separation factor at the same time. In addition, the pervaporation performance of the AlBTC/CS MMMs in butanol dehydration clearly exceeds the upper limit of the membranes reported previously. It proves that the as-prepared AlBTC MOA and AlBTC/CS MMMs in this work, are promising materials in the pervaporation process. Key words: Pervaporation, Mixed Matrix Membranes, Metal-Organic Aerogel, alochol dehydration

My work deals with the problem of alcohol consumption of high school and apprentice students. The goal of my work was to find out what drinks youths prefer and how much of it they drink daily. The next goal was to find out the alcohol consumption of high school and apprentice students. In this research I evaluated how often youths drink alcohol, at what age they first drank it and what their opinion is about its effect on human health. In the theoretical part of this work I dealt with a better drinking regime, different kinds of beverages and I evaluated different alcoholic and non- alcoholic beverages according to their effects on human health. I have described different examples of diseases that are caused by overconsumption of alcohol and those that people with alcohol addiction suffer from. For extra interest I have described the origin of different beverages. In the research part I dealt with the drinking regime of high school and apprentice students. I found out what sweet and sugar free beverages students and apprentices drink and how much they drink daily. It also deals with differences in alcohol consumption between students and apprentices, if boys drink more alcohol than girls and if smokers drink more alcohol than non- smokers. To obtain the results I used questionnaires and gave them to students at high schools and apprentices at vocational schools in České Budějovice. The results were processed in MS Excel. The research confirmed all expected hypothesis. The first confirmed hypothesis was that apprentices drink alcohol more often than high school students. The next confirmed hypothesis was that the above mentioned group does not follow a correct drinking regime. The third confirmed hypothesis was that boys drink alcohol more often than girls. The hypothesis that expected that students and apprentices who smoke drink alcohol more often was also confirmed. The last confirmed hypothesis was, that youths prefers beverages with a content of sugar more than water and sugar free tea.

The diploma thesis deals with analysis of the drinking regime of students of the Technical and Economic University (VŠTE) in České Budějovice. The theoretical part contains informations of the drinking regime in general, the suitability of widely discussed and used beverages. At the end of the theoretical part are the best recommendations, which todays literature, studies and other sources can offer. I have used questionnaire survey for the quantitative research. A total of 1515 students of the Technical and Economic University in České Budějovice have attented this questionnaire survey. Obtained answers are then evulated and compared with given hypotheses in the practical part.

碩士
東海大學
應用化學系
82
The catalytic reactions of ethanol, 1-propanol and 2-propanol were studied at 200~300℃ and atmospheric pressure in a fixed- bed, integral flow reactor over a variety of catalysts, i.e., HZSM-5 zeolite with different molar ratios of silica to alumina (31,51 and 75) and calcination temperatures (400,600 and 800℃) ,HZSM-5 exchanged with alkali metal ion, clays and pillared clays. The conversion of aliphatic alcohol and the selectivity of olefin product increase with increasing the reaction temperature. For the reaction of ethanol and 1-propanol over ZSM-5 type zeolites, both the conversion and the olefin selectivity decrease as the calcination temperature and the basicity of exchanged alkali metal increase. Similar results were observed on the reaction of 2-propanol over HZSM-5 exchanged with alkali metal ion. With regard to the clay type catalyst, K10 and Cr-PM exhibit better conversion of aliphatic alcohol. Based on the TPD measurements of ammonia, HZSM-5 owns strong and weak acid sites. Both the total acid amount and the acid strength decrease with increasing the silica to alumina ratio ] and the calcination temperature of HZSM-5 or ion exchanged with K+ and Cs+. For the clay type catalyst, Cr-PM and K10 exhibit greater acid amount and acid strength. The conversion of alcohol is correlated with the total acid amount of the catalyst. The catalyst strong and weak acid sites favor the formation of olefin and ether product, respectively. For the reaction path, consecutive reaction from ethanol to produce diethylether and ethylene was found whereas competitive reaction occurred in the reaction of 1-propanol to or dipropylether and propylene. With 2- propanol, propylene was the main product.

Brønsted and Lewis acid sites located within microporous solids catalyze a variety of chemical transformations of oxygenates and hydrocarbons. Such reactions occur in condensed phases in envisioned biomass and shale gas upgrading routes, motivating deeper fundamental understanding of the reactivity-determining interactions among active sites, reactants, and solvents. The crystalline structures of zeolites, which consist of SiO₄ tetrahedra with isomorphously-substituted M⁴⁺ (e.g., Sn⁴⁺, Ti⁴⁺) as Lewis acid sites, or Al³⁺ with charge-compensating extraframework H⁺ as Brønsted acid sites, provide a reasonably well-defined platform to study these interactions within confining voids of molecular dimension. In this work, gas-phase probe reactions that afford independent control of solvent coverages are developed and used to interpret measured rate data in terms of rate and equilibrium constants for elementary steps, which reflect the structure and stability of kinetically relevant transition states and reactive intermediates. The foundational role of quantitative kinetic information enables building molecular insights into the mechanistic and active site requirements of catalytic reactions, when combined with complementary tools including synthetic approaches to prepare active sites and surrounding environments of diverse and intended structure, quantitative methods to characterize and titrate active sites and functional groups in confining environments, and theoretical modeling of putative active site structures and plausible reaction coordinates.

Allylic amines are important and fundamental building blocks due to their wide-spread occurrence in many natural products and the ability to further functionalize them by transformations on the double bond to generate a diverse range of compounds. Transition-metal catalyzed allylic substitution represents an attractive and efficient approach towards the synthesis of these allylic amines. However, limitations associated with the traditional methods developed for such allylic amination in terms of regiospecificity, atom economy and generality in these transformations, combined with the importance of allylic amination, prompted us to develop novel atom efficient and regiospecific methods for their synthesis.

A 1:1 mixture of AuCl[P(t-Bu)₂o-biphenyl] (5 mol %) and AgSbF₆ (5 mol %) catalyzed the intermolecular amination of underivatized allylic alcohols with 1-methyl-2-imidazolidinone and related nucleophiles. The first examples of intermolecular allylic amination was developed that in the case of gamma-unsubstituted and gamma-methyl-substituted allylic alcohols, occurred with high gamma-regioselectivity and syn-stereoselectivity.

A 1:1 mixture of AuCl[P(t-Bu)₂o-biphenyl] (5 mol %) and AgSbF₆ (5 mol %) also served as a very efficient catalytic system for the intramolecular amination of allylic alcohols with alkylamines to form substituted pyrrolidine and piperidine derivatives. The protocol was effective for a range of secondary as well as primary alkylamines as nucleophiles with different substitutions on the alkyl chain tethering the nucleophile to the allylic alcohol. The method was also extended towards the total synthesis of the naturally occurring alkaloid (S)-(+)-coniine in two steps from the starting (R,Z)-8-(N-benzylamino)-3-octen-2-ol. In addition, gold(I)-catalyzed cyclization of (R,Z)-8-(N-benzylamino)-3-octen-2-ol (96% ee) led to isolation of (R,E)-1-benzyl-2-(1-propenyl)piperidine in 99% yield and 96% ee that established the net syn-addition of the nucleophile with respect to the departing hydroxyl group.

A bis(gold) phosphine complex (S)-Au₂Cl₂(DTBM-MeOBIPHEP) (2.5 mol %) and AgClO₄ (5 mol %) catalyzed the intramolecular enantioselective dehydrative amination of allylic alcohols with carbamates to form the corresponding substituted pyrrolidines, piperidines, morpholines and piperazines in excellent yields and with up to 95% ee. This general and effective protocol tolerated a range of carbamates as well as sulfonamides as nucleophiles. Cyclization of chiral amino allylic alcohols that possessed a stereogenic homoallylic or hydroxy-bound carbon atom occurred with an overriding catalyst control of asymmetric induction. In addition, stereochemical analysis of the cyclization of a chiral non-racemic secondary allylic alcohol established the net syn-displacement of the hydroxy group by the carbamate nucleophile.

Alongside allylic amination, a cationic gold(I)-N-heteocyclic carbene complex catalyzed the intermolecular etherification (alkoxylation) of allylic alcohols in a regiospecific and syn-stereoselective fashion. The transformation was highly efficient to utilize unactivated primary and secondary alcohols as nucleophiles with different allylic alcohols to undergo regiospecific etherification. Employment of a chiral nonracemic secondary allylic alcohol, trans-5-(benzyloxy)pent-3-en-2-ol (98% ee) showed a high level of chirality transfer on reaction with n-butanol to the corresponding allylic ether, (2-butoxypent-3-en-1-yloxy)methylbenzene (97% ee) and established the net syn-addition of the alcohol nucleophile with respect to the departing hydroxyl group of the allylic alcohol.

Dissertation