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Membrane Reactor (membrane + reactor)
Kinds of Membrane Reactor Terms modified by Membrane Reactor Selected AbstractsPolyurethane- and Polystyrene-Supported 2,2,6,6-Tetramethyl- piperidine-1-oxyl (TEMPO); Facile Preparation, Catalytic Oxidation and Application in a Membrane ReactorADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2008Muhammad Afzal Subhani Abstract In this contribution, the facile synthesis of two new polymer-supported 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) catalysts and their application in the catalytic oxidation of alcohols to carbonyl compounds are described. For attachment of the TEMPO group to the polymer an isocyanate functionalized polymer is chosen. This new approach facilitates the synthesis in comparison with previously existing methods which generally require deprotonation of TEMPO prior to reaction with the polymer. Following this approach, polyurethane (PU)- and polystyrene (PS)-based TEMPO catalysts are prepared in a one-step reaction from commercially available compounds. Both polymer-supported catalysts showed promising yields for a variety of substrates using inorganic and/or organic co-oxidants in biphasic and/or monophasic systems. The recyclability of the corresponding catalysts was studied in repetitive batch experiments using filtration or distillation depending on the support type. Furthermore, application of the homogeneous polyurethane-supported TEMPO for the selective oxidation of benzyl alcohol in a continously operated membrane reactor is demonstrated. [source] ChemInform Abstract: Hydrogen Production by Water Dissociation in Surface-Modified BaCoxFeyZr1-x-yO3-, Hollow-Fiber Membrane Reactor with Improved Oxygen Permeation.CHEMINFORM, Issue 41 2010Heqing Jiang Abstract A BaCoxFeyZr1-x-yO3-, hollow-fiber membrane is surface modified by a catalytically active BaCoxFeyZr0.9-x-yPd0.1 O3-, porous layer. [source] ChemInform Abstract: The Selective Oxidation of Benzyl Alcohols in a Membrane Reactor.CHEMINFORM, Issue 31 2001G. Grigoropoulou Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Porphyrin-Functionalized Dendrimers: Synthesis and Application as Recyclable Photocatalysts in a Nanofiltration Membrane ReactorCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2005Suhas A. Chavan Dr. Abstract The convergent synthesis of a series of porphyrin-functionalized pyrimidine dendrimers has been accomplished by a procedure involving the nucleophilic aromatic substitution (NAS) as a key reaction step. The resulting dendritic porphyrin catalysts show high activity in the light-induced generation of singlet oxygen (1O2) from ground-state oxygen. These materials are synthetically useful photosensitizers for the oxidation of various olefinic compounds to the corresponding allylic hydroperoxides. Catalytic activities and regio- and stereoselectivities of the dendritic photosensitizers are comparable to those observed for mononuclear porphyrin catalysts. Recycling of the dendrimer-enlarged homogeneous photocatalysts was possible by solvent-resistant nanofiltration (SRNF) by using an oxidatively stable membrane consisting of a polysiloxane polymer and ultrastable Y zeolite as inorganic filler. Moreover, this membrane technology provides a safe way to isolate the hydroperoxide products under very mild conditions. The membrane showed high retention for the macromolecular catalysts, even in chlorinated solvents, but some oxidative degradation of the porphyrin units of the dendrimer was observed over multiple catalytic runs. [source] A simplified method for limit conversion calculation in membrane reactorsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Fausto Gallucci Abstract Membrane reactors (MRs) are often used to carry out equilibrium limited reactions. This is because the thermodynamic equilibrium is a strong constrain for traditional systems. Even with very active catalysts, traditional reactors (TRs) cannot give conversions higher than those allowed by the thermodynamic equilibrium. On the contrary, MRs are able to shift the equilibrium of a traditional system owing to the removal of at least one reaction product that takes place simultaneously to the reaction. In this work, a simplified method for the calculation of limit conversion in MR is discussed and compared with literature methods. The typical method for calculating equilibrium conversions in TR is also discussed. It has been demonstrated that the simplified method applied to two reaction systems gives fast predictions of the limit conversion for MR. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Fuel Cells, Advanced Reactors and Smart Catalysis: The Exploitation of Ceramic Ion-Conducting MembranesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2003I.S. Metcalfe Abstract Membrane reactors are of great interest in the chemical industries because they offer the possibility of improved yields, improved selectivities and more compact plant. However, a significant barrier to their uptake is the unavailability of membrane systems having the required performance at an acceptable cost. In this paper we will explore the use of one class of membrane that has the potential to deliver high performance at reasonable cost. Ion-conducting ceramic membranes can be used in a wide range of high temperature applications including fuel cells, advanced reactors and even smart catalytic systems. [source] Preventing biofilm formation: promoting cell separation with terpenesFEMS MICROBIOLOGY ECOLOGY, Issue 3 2007Carla C.C.R. De Carvalho Abstract Both carveol and carvone were effective in dispersing Rhodococcus erythropolis cells that were being stimulated to aggregate by the presence of organic solvents. The two terpenes influenced the fatty acid composition of the cell membrane, decreasing the percentage of fatty acids with more than 16 carbon atoms, and thus cell hydrophobicity, and also the degree of saturation of the fatty acids. In the presence of 250 ,mol of terpene, the volume of biofilm was reduced by one third in comparison with biofilms in the absence of terpenes. The percentage of aggregated cells was also found to depend on carvone concentration during the bioconversion of carveol to carvone, in a membrane reactor. The extent of cell aggregation decreased from 90% to 10% when carvone concentration reached ca. 48 mM in the organic phase. [source] Polyurethane- and Polystyrene-Supported 2,2,6,6-Tetramethyl- piperidine-1-oxyl (TEMPO); Facile Preparation, Catalytic Oxidation and Application in a Membrane ReactorADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2008Muhammad Afzal Subhani Abstract In this contribution, the facile synthesis of two new polymer-supported 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) catalysts and their application in the catalytic oxidation of alcohols to carbonyl compounds are described. For attachment of the TEMPO group to the polymer an isocyanate functionalized polymer is chosen. This new approach facilitates the synthesis in comparison with previously existing methods which generally require deprotonation of TEMPO prior to reaction with the polymer. Following this approach, polyurethane (PU)- and polystyrene (PS)-based TEMPO catalysts are prepared in a one-step reaction from commercially available compounds. Both polymer-supported catalysts showed promising yields for a variety of substrates using inorganic and/or organic co-oxidants in biphasic and/or monophasic systems. The recyclability of the corresponding catalysts was studied in repetitive batch experiments using filtration or distillation depending on the support type. Furthermore, application of the homogeneous polyurethane-supported TEMPO for the selective oxidation of benzyl alcohol in a continously operated membrane reactor is demonstrated. [source] Preparative Enzymatic Synthesis of the Acylglucuronide of Mycophenolic AcidADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6-7 2003Matthias Kittelmann Abstract The acylglucuronide (3) of mycophenolic acid (1) was enzymatically synthesised on a preparative scale (450,mg substrate) under optimised reaction conditions with 51% conversion. By screening 9 liver homogenates from 8 vertebrate species, it was shown that only with liver homogenate from horse as the catalyst were the acyl- (3) and the O -glucuronide (2) were formed in a ca. 1,:,1 ratio. With homogenates from other sources, the O -glucuronide (2) was produced in high excess. By optimising the concentration of the co-substrate UDP-glucuronic acid and the reaction temperature, the conversion to the acylglucuronide (3) was increased from initially 34 to 55% and the ratio of acyl- (3) to O -glucuronide (2) from 1.5,:,1 to 3.9,:,1. The reaction was also performed continuously in an enzyme membrane reactor, however, with lower conversion yield and therefore, higher specific UDP-glucuronic acid consumption. [source] Removal of H2S and volatile organic sulfur compounds by silicone membrane extractionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2009I. Manconi Abstract BACKGROUND: This study explores an alternative process for the abatement and/or desulfurization of H2S and volatile organic sulfur compounds (VOSC) containing waste streams, which employs a silicone-based membrane to simultaneously remove H2S and VOSC. An extractive membrane reactor allows the selective withdrawal of VOSC and H2S simultaneously from the waste stream, while preventing direct contact between the waste stream and the absorbing solution and/or the biological treatment system. The influence of the sulfur compounds, membrane characteristics, extractant and pH was studied. RESULTS: Sulfide and the VOCS studied, i.e. methanethiol (MT), ethanethiol (ET) and dimethylsulfide (DMS) were removed from the synthetic wastewater using a silicone rubber membrane. Methanethiol showed the highest (8.72 × 10,6 m s,1) overall mass transfer coefficient (kov) and sulfide the lowest kov value (1.23 × 10,6 m s,1). Adsorption of the VOCS into the silicone membrane reduced the overall mass transfer coefficient. The kov when using Fe(III)EDTA, as extractant (5.81 × 10,7 m s,1) for sulfide extraction was one order of magnitude lower than with anaerobic water (2.54 × 10,6 m s,1). On the other hand, the sulfide removal efficiency with Fe(III)EDTA, was higher (84%) compared with anaerobic water (60%) as extractant. An additional mass transfer resistance was formed by elemental sulfur which remained attached to the membrane surface. CONCLUSIONS: Extraction of sulfide and VOCS from a synthetic wastewater solution through a silicone rubber membrane is a feasible process as alternative to the techniques developed to treat VOSC emissions. Optimizing the aqueous absorption liquid can increase the efficiency of extraction based processes. Copyright © 2008 Society of Chemical Industry [source] Oxidative dehydrogenation of propane in a perovskite membrane reactor with multi-step oxygen insertionAICHE JOURNAL, Issue 9 2010Oliver Czuprat Abstract A membrane reactor incorporating a hollow fiber with successive parts of oxygen permeable and passivated surface segments has been developed and was used for the oxidative dehydrogenation (DH) of propane. This membrane geometry allows a controlled oxygen feeding into the reactor over its axial length. In the oxidative DH, the thermodynamic limitation of propane DH can be overcome. By using this novel hollow fiber membrane reactor with a Pt/Sn/K DH catalyst, oxygen separation and propene formation could be established even at temperatures as low as 625°C with long-term stability. Combining the hollow fiber membrane and the DH catalyst, the highest propene selectivity of 75% was observed at a propane conversion of 26% and 625°C whereas the best propene yield of 36% was obtained at 675°C (48% propene selectivity). The performance of this reactor is evaluated by applying various reaction conditions. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Oxygen permeability and structural stability of a novel tantalum-doped perovskite BaCo0.7Fe0.2Ta0.1O3,,AICHE JOURNAL, Issue 3 2010Huixia Luo Abstract Dense BaCo0.7Fe0.2Ta0.1O3,, (BCFT) perovskite membranes were successfully synthesized by a simple solid state reaction. In situ high-temperature X-ray diffraction indicated the good structure stability and phase reversibility of BCFT at high temperatures. The thermal expansion coefficient (TEC) of BCFT was determined to amount 1.02 × 10,5 K,1, which is smaller than those of Ba0.5Sr0.5Co0.8Fe0.2O3,, (BSCF) (1.15 × 10,5 K,1), SrCo0.8Fe0.2O3,, (SCF) (1.79 × 10,5 K,1), and BaCo0.4Fe0.4Zr0.2O3,, (BCFZ) (1.03 × 10,5 K,1). It can be seen that the introduction of Ta ions into the perovskite framework could effectively lower the TEC. Thickness dependence studies of oxygen permeation through the BCFT membrane indicated that the oxygen permeation process was controlled by bulk diffusion. A membrane reactor made from BCFT was successfully operated for the partial oxidation of methane to syngas at 900°C for 400 h without failure and with the relatively high, stable oxygen permeation flux of about 16.8 ml/min cm2. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Computational study of staged membrane reactor configurations for methane steam reforming.AICHE JOURNAL, Issue 1 2010Abstract This article and Part II report a computational study carried out to analyze the performance achievable using a staged membrane reactor in the methane steam reforming process to produce high purity hydrogen. A reaction/separation unit in which reactive stages are laid out in series to permeative stages already proposed in literature (Caravella et al., J Memb Sci. 2008;321:209,221) is modified here to increase its flexibility. The improvement includes the consideration of the Pd-based membrane along the entire length. Two- and ten-staged reactors are examined in terms of methane conversion, hydrogen recovery factor and hydrogen recovery yield, considering co- and counter-current flow configurations. Individual stage lengths are obtained by maximizing either methane conversion or hydrogen recovery yield, comparing the results to the ones of an equivalent traditional reactor and a conventional membrane reactor. The analysis allows demonstrating that the counter-current configuration leads to significant improvements in the hydrogen recovery, but proves almost irrelevant with respect to methane conversion. The influence of the number of stages and the amount of catalyst is quantified in the accompanying part II article. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Computational study of staged membrane reactor configurations for methane steam reforming.AICHE JOURNAL, Issue 1 2010Abstract The present work complements part I of this article and completes a computational analysis of the performances of staged membrane reactors for methane steam reforming. The influence of the number of stages and catalyst amount is investigated by comparing the methane conversion and hydrogen recovery yield achieved by an equisized-staged reactor to those of an equivalent conventional membrane reactor for different furnace temperatures and flow configurations (co- and counter-current). The most relevant result is that the proposed configuration with a sufficiently high number of stages and a significantly smaller catalyst amount (up to 70% lower) can achieve performances very close to the ones of the conventional unit in all the operating conditions considered. This is equivalent to say that the staged configuration can compensate and in fact substitute a significant part of the catalyst mass of a conventional membrane reactor. To help the interpretation of these results, stage-by-stage temperature and flux profiles are examined in detail. Then, the quantification of the performance losses with respect to the conventional reactor is carried out by evaluating the catalyst amount possibly saved and furnace temperature reduction. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Theoretical study of a membrane reactor for the water gas shift reaction under nonisothermal conditionsAICHE JOURNAL, Issue 12 2009María E. Adrover Abstract A simulation of a membrane reactor for the water gas shift reaction is carried out by means of a 1D pseudo-homogeneous nonisothermal mathematical model. The composite membrane consists of a dense layer of Pd (selective to H2) supported over a porous ceramic layer. The effect of temperature, overall heat-transfer coefficient, and mode of operation on the membrane reactor performance and stability are analyzed, and the results obtained are compared with those corresponding to a reactor with no hydrogen permeation. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Oxygen selective ceramic hollow fiber membranes for partial oxidation of methaneAICHE JOURNAL, Issue 10 2009Haihui Wang Abstract A BaCoxFeyZrzO3,, (BCFZ) perovskite hollow fiber membrane was used to construct reactors for the partial oxidation of methane (POM) to syngas. The performance of the BCFZ fibers in the POM was studied (i) without any catalyst, (ii) with catalyst-coated fibers, and (iii) with catalyst packed around the fibers. In addition to the performance in the POM, the stability of the BCFZ hollow fiber membranes was investigated for the different catalyst arrangements. Best stability of the BCFZ hollow fiber membrane reactor in the POM could be obtained if the reforming catalyst is placed behind the oxygen permeation zone. It was found that a direct contact of the catalyst and the fiber must be avoided which could be achieved by coating the fiber with a gold film. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Design of mixed conducting ceramic membranes/reactors for the partial oxidation of methane to syngasAICHE JOURNAL, Issue 10 2009Xiaoyao Tan Abstract The performance of mixed conducting ceramic membrane reactors for the partial oxidation of methane (POM) to syngas has been analyzed through a two-dimensional mathematical model, in which the material balance, the heat balance and the momentum balance for both the shell and the tube phase are taken into account. The modeling results indicate that the membrane reactors have many advantages over the conventional fixed bed reactors such as the higher CO selectivity and yield, the lower heating point and the lower pressure drop as well. When the methane feed is converted completely into product in the membrane reactors, temperature flying can take place, which may be restrained by increasing the feed flow rate or by lowering the operation temperature. The reaction capacity of the membrane reactor is mainly determined by the oxygen permeation rate rather than by the POM reaction rate on the catalyst. In order to improve the membrane reactor performance, reduction of mass transfer resistance in the catalyst bed is necessary. Using the smaller membrane tubes is an effective way to achieve a higher reaction capacity, but the pressure drop is a severe problem to be faced. The methane feed velocity for the operation of mixed conducting membrane reactors should be carefully regulated so as to obtain the maximum syngas yield, which can be estimated from their oxygen permeability. The mathematical model and the kinetic parameters have been validated by comparing modeling results with the experimental data for the La0.6Sr0.4Co0.2Fe0.8O3-, (LSCF) membrane reactor. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] A novel inorganic hollow fiber membrane reactor for catalytic dehydrogenation of propaneAICHE JOURNAL, Issue 9 2009Zhentao Wu Abstract A novel inorganic hollow fiber membrane reactor (iHFMR) has been developed and applied to the catalytic dehydrogenation of propane to propene. Alumina hollow fiber substrates, prepared by a phase inversion/sintering method, possess a unique asymmetric structure that can be characterized by a very porous inner surface from which finger-like voids extend across ,80% of the fiber cross-section with the remaining 20% consisting of a denser sponge-like outer layer. In contrast to other existing Pd/Ag composite membranes, where an intermediate ,-Al2O3 layer is often used to bridge the Pd/Ag layer and the substrate, the Pd/Ag composite membrane prepared in this study was achieved by coating the Pd/Ag layer directly onto the outer surface of the asymmetric substrate. After depositing submicron-sized Pt (0.5 wt %)/,-alumina catalysts in the finger-like voids of the substrates, a highly compact multifunctional iHFMR was developed. Propane conversion as high as 42% was achieved at the initial stage of the reaction at 723 K. In addition, the space-time yields of the iHFMR were ,60 times higher than that of a fixed bed reactor, demonstrating advantages of using iHFMR for dehydrogenation reactions. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Design of a thermally balanced membrane reformer for hydrogen productionAICHE JOURNAL, Issue 10 2008David S. A. Simakov Abstract Hydrogen production by autothermal methane steam reforming in a catalytic fixed bed membrane reactor has been analyzed and simulated. The two-compartment reactor indirectly couples the endothermic steam reforming with methane oxidation, while hydrogen is separated by a permselective Pd membrane. Simulations of the reactor, using published kinetics, map the acceptable domain of operation and the optimal set of operating parameters. The simulations exhibit slow-moving thermal fronts and the steady-state operation domains bounded by stationary fronts, separating domains of upstream and downstream-moving fronts. Front velocity depends on thermal coupling and hydrogen separation. An analytical approximation for the thermal front velocity in a thermally balanced reactor has been developed. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Performance study of heptane reforming in the dense ceramic membrane reactorsAICHE JOURNAL, Issue 1 2008Wenliang Zhu Abstract Heptane reforming was investigated in three dense ceramic membrane reactors, where the membranes were modified differently with reforming catalyst. Each reactor displayed distinctive catalytic behavior. The reactor with a bare membrane showed low catalytic activity and low oxygen permeation flux (JO2), but gave stable performance. The left two membranes reactors modified with catalyst both displayed shift processes at the preliminary stage of membrane reaction, not only in JO2 but also in the selectivity of all products. Moreover, the membrane reactor with more catalyst gave higher performance in the case of JO2 and CO selectivity. The observed shift phenomena are due to the activation of catalyst on the membrane surface, and the different amounts of catalyst produce different impaction on the membrane reactions. On the basis of the results in three membrane reactors, a reaction pathway of hydrocarbon reforming in dense ceramic membrane reactor is proposed. Being some different from combustion and reforming mechanism (CRR), hydrocarbon reforming in dense ceramic membrane reactor has its own characteristics. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source] Oxidative coupling of methane in dense ceramic membrane reactor with high yieldsAICHE JOURNAL, Issue 10 2002F. T. Akin Oxidative coupling of methane (OCM) was studied with dense tubular Bi1.5Y0.3Sm0.2O3 (BYS) membranes at various temperatures (870,930°C). BYS powders were synthesized by a citrate method. Tubular-shaped dense membranes of BYS in the fluorite-type FCC phase structure were fabricated by cold isostatic pressing with green machining. The best one-pass C2 (C2H4 + C2H6) yield achieved for OCM in the BYS dead-end membrane reactor was 35% at a C2 selectivity of 54% at 900°C. At the same C2 yield, the membrane reactor mode gives C2 selectivity of over 200% higher than the cofeed mode in the same membrane reactor under similar conditions. The oxygen permeation fluxes through tubular BYS membrane reactors under OCM reaction conditions are approximately 1.5 to 3.5 times higher than those under oxygen permeation conditions with He as the purge. After 6 days of OCM, BYS membrane remained in good integrity with minor phase segregation observed at the reaction side of the membrane. [source] Bioactive peptide production by hydrolysis of porcine blood proteins in a continuous enzymatic membrane reactorJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2009Jen-Ting Wei Abstract BACKGROUND: During slaughter a hog produces approximately 3 L of blood. However, only a small proportion of porcine blood is currently used in food, feed or fertiliser, most of it being treated as waste and discarded. In this study the possibility of hydrolysing porcine blood proteins by enzyme in a membrane reactor for the production of bioactive peptides was investigated. Red blood corpuscles, blood plasma and defibrinated blood plasma were hydrolysed by various proteases, and the hydrolysates were evaluated for bioactive properties. RESULTS: The hydrolysate produced by hydrolysing red blood corpuscles with a mixture of trypsin, chymotrypsin and thermolysin had the highest angiotensin I-converting enzyme (ACE)-inhibitory activity (IC50 = 0.58 mg mL,1) and scavenging effect on ,,,-diphenyl-,-picrylhydrazyl (DPPH) (65%) after 6 and 10 h of hydrolysis respectively. When the hydrolysis was carried out in an enzymatic membrane reactor with an enzyme/substrate ratio of 1:5 and a residence time of 100 min, the process reached steady state in 2 h. The ACE-inhibitory activity of the product during the steady state process was 86% and its scavenging effect on DPPH was 54%. The membrane process also decolourised the enzyme-hydrolysed product, thus improving the appearance of the product. CONCLUSION: This study demonstrated that hydrolysates of porcine blood possess antihypertensive and antioxidant activities. Using red blood corpuscles as the substrate, the hydrolysis could be carried out in a membrane reactor with a mixture of proteases to produce bioactive peptides continuously. Therefore processing of porcine blood in an enzymatic membrane reactor is a potential method for producing a health-promoting product. Copyright © 2008 Society of Chemical Industry [source] Simulation of autothermal reforming in a staged-separation membrane reactor for pure hydrogen productionTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2008Anwu Li Abstract Steam methane reforming with oxygen input is simulated in staged-separation membrane reactors. The configuration retains the advantage of regular membrane reactors for achieving super-equilibrium conversion, but reaction and membrane separation are carried out in two separate units. Equilibrium is assumed in the models given the excess of catalyst. The optimal pure hydrogen yield is obtained with 55% of the total membrane area allocated to the first of two modules. The performance of the process with pure oxygen input is only marginally better than with air. Oxygen must be added in split mode to reach autothermal operation for both reformer modules, and the oxygen input to each module depends on the process conditions. The effects of temperature, steam-to-carbon ratio and pressure of the reformer and the area of the membrane modules are investigated for various conditions. Compared with a traditional reformer with an ex situ membrane purifier downstream, the staged reactor is capable of much better pure hydrogen yield for the same autothermal reforming operating conditions. Le reformage du méthane à la vapeur avec apport d'oxygène est simulé dans des réacteurs à membranes de séparation étagés. Cette configuration conserve l'avantage des réacteurs à membranes réguliers pour la conversion en sur-équilibre, mais la réaction et la séparation par membranes sont réalisées dans deux unités séparées. L'équilibre est supposé dans les modèles selon l'excès en catalyseur. Le rendement optimal en hydrogène pur est obtenu avec 55% de la surface totale des membranes affectée au premier des deux modules. La performance du procédé avec apport d'oxygène pur n'est que marginalement meilleure par rapport à l'air. De l'oxygène peut être ajouté en mode fractionné pour atteindre un fonctionnement autothermique pour les deux modules reformeurs, et l'apport d'oxygène de chaque module dépend des conditions de procédé. Les effets de la température, du rapport vapeur-carbone et de la pression du reformeur et de la surface des modules membranaires sont étudiés pour diverses conditions. Comparativement au reformeur traditionnel avec, en aval, un purificateur à membranes ex-situ, le réacteur étagé peut donner un bien meilleur rendement en hydrogène pur pour les mêmes conditions opératoires de reformage autothermique. [source] Phenol recovery from simulated wastewater using a vertical membrane reactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Manoj Jhanwar Abstract Phenol was recovered from the simulated wastewater in the form of a useful product, allyl phenyl ether, using A-172 membrane as phase-transfer catalyst in a batch and a continuous membrane reactor. The effects of temperature, agitation rates and flow rates of aqueous and organic phases, and concentrations of phenol and allyl bromide on the yield of allyl phenyl ether in the organic phase and phenol removal in the aqueous phase after the reaction were studied. Activation energy and turnover number of the reaction were calculated as well. In the batch mode, the phenol concentration in the treated aqueous phase was found to be < 2 ppm, reduced from 5000 ppm, and more than 99% of the phenol was recovered in the form of allyl phenyl ether after reacting for 180 min. In a continuous mode, the phenol concentration can be reduced from 5000 to 100 ppm in the steady state operation of the reactor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Syntheses of esters through poly(styrene sulfonic acid)/poly(vinyl alcohol) membrane reactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Tadashi Uragami Abstract Cation exchange membranes prepared from poly(styrene sulfonic acid) (PSA) and poly(vinyl alcohol) (PVA) were cross-linked by both glyoxal and gultaraledehyde and cross-linked membranes furthermore were annealed. The ion exchange capacity of the resulting PSA/PVA membranes increased, and the water content and degree of swelling of PSA/PVA membrane decreased with increasing annealing time. The syntheses of esters from alcohol and acetic acid through various PSA/PVA membranes have been carried out in a diaphragm type cell consisting of two detachable parts in which the membrane was set in the middle of the two parts of cell. When an aqueous solution of alcohol and acetic acid on one part of cell and p -chloro benzene (Cl-Bz) on another part were set, esters formed by the catalytic action of PSA/PVA membrane increased on the Cl-Bz phase with time. These results support that the PSA/PVA membrane could perform both the reaction and separation. The formation of esters in this membrane reactor was a secondary reaction as well as general the esterification between alcohols and acids. The catalytic action in the esterification of the PSA/PVA membranes prepared by changing the ratio of PSA/PVA and the amount of casting solution was also investigated. The rate of esterification reaction was significantly dependent on the number of sulfonic acid group in the effective membrane volume. The rate of reaction per mEq SO3H increased with an increase of the degree of swelling of the membrane and decreasing membrane thickness. In the esterifications of methanol, ethanol and n -propanol with acetic acid, the reactivity through the PSA/PVA membrane was higher than that with HCl as catalyst. In that of n -butanol with acetic acid, however, it was vice versa. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Estimating limit conversion for methane steam reforming in a palladium membrane reactor using countercurrent sweep gasASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010S. Hara Abstract Generally speaking, conversion increases with increasing reactor length to approach a certain value: so-called limit conversion. Limit conversion for a membrane reactor with a cocurrent sweep gas has been studied extensively. However, characteristics of limit conversion for the countercurrent, which are examined in this study, remain unclear. First, conversions of MRs with different reactor lengths were calculated using a conventional mode of integrating differential equations. Results confirmed that limit conversion is not always 100%, even for the countercurrent. Long MRs were found to have a pseudo-constant state inside, characterized by an extremely low apparent reaction rate and permeation rate. Secondly, a novel approach to estimate limit conversion was developed: reaction equilibrium constants and hydrogen partial pressure balance between both sides were applied not for the end of the reactor but for the pseudo-constant state. This new approach suggests that limit conversion for the countercurrent depends on the reaction temperature, feed-side and permeation-side pressures, feed-gas composition, and the sweep rate. It is fundamentally independent of reaction kinetic equations and hydrogen permeation-rate properties. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Innovative membrane based process for the selective oxidation of light alkanes assisted by the Fenton systemASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010C. Espro Abstract Selective oxidation of light alkanes under mild conditions (temp, 80,120 °C; pressure, 140 kPa) mediated by Fe2+/H2O2 Fenton system on Nafion based composite membranes is studied in a multifunctional three phase catalytic membrane reactor (3PCMR). The role of textural properties and acid functionality on the catalytic performance of the Nafion composite membranes is outlined. The features of the multifunctional 3PCMR, enabling reaction along with product separation and recovery, are discussed. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Membrane reactor modelling, validation and simulation for the WGS reaction using metal doped silica membranesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010S. Battersby Abstract In this work, a Matlab Simulink© model was developed to analyse and predict the performance of a metal doped silica membrane reactor for H2 production via both the high and low temperature water gas shift reaction. An activated transport model for mixed gas separation with combined reaction was developed to model the effects within a membrane reactor unit. The membrane reactor was modelled as a number of perfectly mixed compartments containing a catalyst bed and a gas selective membrane. The combined model provided a good fit to experimentally measured results for higher conversions up to equilibrium, which is generally the case for industrial applications. Simulation results showed that H2 separation and H2 recovery improved with pressure, due to the H2 concentration driving force across the membrane. For a single stage membrane reactor unit, a maximum conversion of 93% could be achieved with a H2 recovery rate of 95%. In addition, the membrane reactor efficiency increased at higher temperatures and lower H2O:CO feed ratios, allowing for CO conversion improvements by the membrane reactor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Production of hydrogen via glycerol steam reforming in a Pd-Ag membrane reactor over Co-Al2O3 catalystASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010A. Iulianelli Abstract Generally, biodiesel fuel, when converted from vegetables oils, produces around 10 wt% of glycerol as a byproduct, which could be used for producing hydrogen by a steam-reforming reaction. Different scientific works have been realized in conventional reactors on the steam reforming of glycerol (GSR) in the aqueous or the gas phase. High reaction pressure and a relatively small catalyst deactivation are noticed when GSR is carried out in an aqueous phase, whereas the catalyst deactivation is the main disadvantage in the gas phase. In this work, GSR reaction was performed in a perm-selective Pd-Ag membrane reactor (MR) packed with a Co-Al2O3 commercial catalyst in order to extract a CO-free hydrogen stream and also enhance the performances in terms of glycerol conversion and hydrogen yield with respect to a traditional reactor (TR), both working at weight hourly space velocity (WHSV) = 1.01 h,1, 400 °C and H2O/C3H8O3 = 6/1. In MR, a maximum glycerol conversion of around 45.0% was achieved at 1.0 bar as reaction pressure, whereas it was around 94% at 4.0 bar. Moreover, as best value, more than 60.0% of CO-free hydrogen recovery was achieved in the MR at 4.0 bar and 22.8 of sweep factor (sweep gas to glycerol ratio). Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Remarks on studies for direct production of phenol in conventional and membrane reactorsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Raffaele Molinari Abstract The great interest in the oxidation reaction of benzene to phenol is linked to some disadvantages of the cumene process, such as environmental impact, production of an explosive intermediate, a multi-step process (which involves (1) difficulty to achieve high phenol yield, in relation to the benzene used and (2) high capital investment), and a high acetone production as a co-product which results in an over supply in the market. In this paper, we discuss various studies concerning a new approach based on a one-step and acetone-free method for phenol production. Particular attention is devoted to phenol production processes using various configurations of membrane reactors (MRs) and a photocatalytic membrane reactor (PMR). In particular, the biphasic MR allowed to achieving high selectivity values (97,98%). The described studies have been classified according to oxidant type such as N2O, O2, and H2O2. Each of them shows that direct oxidation of benzene to phenol is a difficult task and further efforts are needed to search and replace the three step traditional process of converting benzene into phenol with a process of direct oxidation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||