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Packed Bed Reactor (packed + bed_reactor)
Selected AbstractsThermal performance of a packed bed reactor for a high-temperature chemical heat pumpINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2001Yukitaka Kato Abstract The thermal performance of a chemical heat pump that uses the reaction system of calcium oxide/lead oxide/carbon dioxide, which is developed for utilization of high-temperature heat above 800°C, is studied experimentally. The thermal performance of a packed-bed reactor of a calcium oxide/carbon dioxide reaction system, which stores and transforms a high-temperature heat source in the heat pump operation, is examined under various heat pump operation conditions. The energy analysis based on the experiment shows that it is possible to utilize high-temperature heat with this heat pump. This heat pump can store heat above 850°C and then transform it into a heat above 900°C under an approximate atmospheric pressure. An applied system that combines the heat pump and a high-temperature process is proposed for high-efficiency heat utilization. The scale of the heat pump in the combined system is estimated from the experimental results. Copyright © 2001 John Wiley & Sons, Ltd. [source] Fast and Enantioselective Production of 1-Aryl-1-propanols through a Single Pass, Continuous Flow ProcessADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2008Miquel Abstract A functional polymer 4, obtained by reaction of (R)-2-(1-piperazinyl)-1,1,2-triphenylethanol with a Merrifield resin, has been loaded in a packed bed reactor and used as catalyst for the continuous enantioselective production of 1-arylpropanols by ethylation of aromatic aldehydes. The high catalytic activity depicted by 4 allows the complete conversion of the substrates with the use of stoichiometric reagent ratios and unprecedently short residence times (down to 2.8,min). In practice, a single-pass operation can be used for all the studied aldehydes, and productions of up to 13.0 mol/g,h are recorded. The sequential operation of the flow system for the uninterrupted synthesis of a small library of enantiopure 1-arylpropanols is also reported. [source] Urease immobilization on an ion-exchange textile for urea hydrolysisJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2006Kyeong-Ho Yeon Abstract Ion-exchange textiles are used as organic supports for urease immobilization with the aim of developing reactive fibrous materials able to promote urea removal. A non-woven, polypropylene-based cation-exchange textile was prepared using UV-induced graft polymerization. Urease was covalently immobilized onto the cation-exchange textile using three different coupling agents: N -(3-dimethylaminopropyl)- N,-ethylcarbodiimide hydrochloride (EDC), N -cyclohexyl- N,-(b -[N -methylmorpholino]ethyl)carbodiimide p -toluenesulfonate (CMC), and glutaraldehyde (GA). The immobilized biocatalyst was characterized by means of FT-IR spectrometry, SEM micrographs, dependence of the enzyme activity on pH and temperature, and according to the kinetic constants of the free and immobilized ureases. The biotextile prepared with EDC in the presence of N -hydroxysuccinimide performs best. The optimum pH was 7.2 for the free urease and 7.6 for the immobilized ureases. The reactivity was maximal at 45 °C for free urease, 50 °C for biotextiles prepared using EDC or CMC, and 55 °C for biotextiles prepared with GA. The activation energy for the immobilized ureases was 4.73,5.67 kcal mol,1, which is somewhat higher than 4.3 kcal mol,1 for free urease. The urea conversion for a continuous-flow immobilized urease reactor is nearly as good as a continuously stirred tank reactor having a much longer residence time, suggesting that the packed bed reactor had sufficient diffusive mixing and residence time to reach nearly optimal results. Urease immobilized on a biotextile using EDC has good storage and operational stability. Copyright © 2006 Society of Chemical Industry [source] Production of L -methionine by immobilized pellets of Aspergillus oryzae in a packed bed reactorJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2002Ying-Jin Yuan Abstract Production of L -methionine by immobilized pellets of Aspergillus oryzae in a packed bed reactor was investigated. Based on the determination of relative enzymatic activity in the immobilized pellets, the optimum pH and temperature for the resolution reaction were 8.0 and 60,°C, respectively. The effects of substrate concentration on the resolution reaction were also investigated and the kinetic constants (Km and Vm) of immobilized pellets were found to be 7.99,mmol,dm,3 and 1.38,mmol,dm,3 h,1, respectively. The maximum substrate concentration for the resolution reaction without inhibition was 0.2,mol,dm,3. The L -methionine conversion rate reached 94% and 78% when substrate concentrations were 0.2 and 0.4,mol,dm,3, respectively, at a flow rate of 7.5,cm3,h,1 using the small-scale packed bed reactor developed. The half-life of the L -aminoacylase in immobilized pellets was 70 days in continuous operation. All the results obtained in this paper exhibit a practical potential of using immobilized pellets of Aspergillus oryzae in the production of L -methionine. © 2002 Society of Chemical Industry [source] Steam reforming of propane in a zirconia membrane reactor with a Rh-supported Ce0.15Zr0.85O2 catalystASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009K. Kusakabe Abstract The steam reforming (SR) of propane for hydrogen production at 400,600 °C in a porous yttria-stabilized zirconia (YSZ) membrane reactor was investigated. The YSZ membrane was used as a hydrogen selective membrane. A Rh-supported Ce0.15Zr0.85O2 catalyst was packed in the membrane reactor because the catalyst was found to be the most suitable catalyst for the low-temperature SR of propane on the basis of the results obtained using a packed bed reactor. The conversion of propane in the membrane reactor was higher than that in a packed bed reactor due to the shift of equilibrium toward the hydrogen-producing side. In spite of relatively low permeation selectivity (ideal H2/CO selectivity = 9 at 100 °C), hydrogen permeation through the membrane caused an increase in the CO2 fraction and a decrease in the CO fraction in reformed gas. This indicates that the water-gas shift reaction was an important contributor in the product distribution in the membrane reactor. Meanwhile, the methane fraction remained largely unchanged, regardless of selective hydrogen permeation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Kinetics of lactose hydrolysis by ,-galactosidase of Kluyveromyces lactis immobilized on cotton fabricBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2003Quinn Zhengkun Zhou Abstract A mathematic model for describing the Michaelis-Menten-type reaction kinetics with product competitive inhibition and side-reaction is proposed. A multiresponse nonlinear simulation program was employed to determine the coefficients of a four-parameter rate expression. The rate expression was compared with the conventional Michaelis-Menten reaction rate models with and without product inhibition. Experimental data were obtained using ,-galactosidase of Kluyveromyces lactis immobilized on cotton fabric in a batch system at a temperature of 37°C and at various initial concentrations of dissolved lactose ranging from 3,12.5% (w/v). The reaction is followed by concentration changes with time in the tank. Samples were obtained after the outlet stream of the packed bed reactor is mixed in a well-stirred tank. High-performance liquid chromatography (HPLC) was applied to monitor the concentrations of all the sugars (reactants as well as products). The four-parameter rate model is featured with a term to describe the formation of trisaccharides, a side-reaction of the enzymatic hydrolysis. The proposed model simulates the process of lactose hydrolysis and the formation of glucose and galactose, giving better accuracy compared with the previous models. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 127,133, 2003. [source] Immobilization of ,-Galactosidase on Fibrous Matrix by Polyethyleneimine for Production of Galacto-Oligosaccharides from LactoseBIOTECHNOLOGY PROGRESS, Issue 2 2002Nedim Albayrak The production of galacto-oligosaccharides (GOS) from lactose by Aspergillus oryzae ,-galactosidase immobilized on cotton cloth was studied. A novel method of enzyme immobilization involving PEI,enzyme aggregate formation and growth of aggregates on individual fibrils of cotton cloth leading to multilayer immobilization of the enzyme was developed. A large amount of enzyme was immobilized (250 mg/g support) with about 90,95% efficiency. A maximum GOS production of 25,26% (w/w) was achieved at near 50% lactose conversion from 400 g/L of lactose at pH 4.5 and 40 °C. Tri- and tetrasaccharides were the major types of GOS formed, accounting for about 70% and 25% of the total GOS produced in the reactions, respectively. Temperature and pH affected not only the reaction rate but also GOS yield to some extend. A reaction pH of 6.0 increased GOS yield by as much as 10% compared with that of pH 4.5 while decreased the reaction rate of immobilized enzyme. The cotton cloth as the support matrix for enzyme immobilization did not affect the GOS formation characteristics of the enzyme under the same reaction conditions, suggesting diffusion limitation was negligible in the packed bed reactor and the enzyme carrier. Increase in the thermal stability of PEI-immobilized enzyme was also observed. The half-life for the immobilized enzyme on cotton cloth was close to 1 year at 40 °C and 21 days at 50 °C. Stable, continuous operation in a plug-flow reactor was demonstrated for about 3 days without any apparent problem. A maximum GOS production of 26% (w/w) of total sugars was attained at 50% lactose conversion with a feed containing 400 g/L of lactose at pH 4.5 and 40 °C. The corresponding reactor productivity was 6 kg/L/h, which is several-hundred-fold higher than those previously reported. [source] | |||||||||||||