Development of a Novel Catalytic Membrane Reactor for Heterogeneous Catalysis in Supercritical CO2

A novel type of high-pressure membrane reactor has been developed for hydrogenation in supercritical carbon dioxide (scCO₂). The main objectives of the design of the reactor are the separate feeding of hydrogen and substrate in scCO₂ for safe reactions in a continuous flow process, and to reduce the reaction time. By using this new reactor, hydrogenation of cinnamaldehyde into hydrocinnamaldehyde has been successfully carried out with 100% selectivity at 50 °C in 10 MPa (H₂: 1 MPa, CO₂: 9 MPa) with a flow rate of substrate ranging from 0.05 to 1.0 mL/min.     

Progress in performance and stability of a contactor-type Catalytic Membrane Reactor for wet air oxidation

Catalytic Membrane Reactors combine a membrane that controls transfers and a catalyst that provides conversion. This paper focuses on the catalytic performance stability of interfacial contactor membranes in the wet air oxidation of formic acid. Stable catalytic membranes with high activity have been developed.     

Hydrolysis of Olive Oil with Immobilized Lipase in a Tapered Column Reactor

Lipase was immobilized in ion exchange resin and then used in the hydrolysis of olive oil to produce fatty acids and glycerol. The time course of hydrolysis of olive oil was investigated in a stirred tank reactor using both of the free and immobilized lipases to find the yield of activity of immobilized enzyme. Continuous hydrolysis of olive oil was also carried out in a tapered column reactor and a cylindrical column reactor with a bottom ID of 10 mm at different upward flow rates. It can be known from experimental results that the degree of hydrolysis of olive oil in the tapered column reactor is moderately better than that in the cylindrical column reactor, the pressure drop in the tapered column reactor is much smaller than that in the cylindrical column reactor.     

Catalytic Dehydrogenation of Ethanol in Ru-Modified Alumina Membrane Reactor

Abstract

Ru-modified alumina composite membranes were prepared by the sol-gel method. The pore size distribution from nitrogen adsorption showed that average pore diameters were 3.1–4.5 nm, and the ideal separation factor was obviously higher than that of a pure γ-AI₂O₃ membrane. Ethanol dehydrogenation was carried out in the Ru-modified alumina membrane reactors. The effects of the reaction temperature, feed rate, and argon sweep flow rate on acetaldehyde yield were investigated. The results showed that the yield of acetaldehyde increased by 25–28% at the same conditions in a Ru-modified alumina membrane reactor. The reduced temperature of the Ru-modified alumina composite membrane was measured by temperature-programmed reduction, and the morphology of the membrane was characterized by SEM, TEM, and XRD.     

膜分离式酶解反应器的研究进展

本文综述了国内外近年来膜分离式酶解反应的研究概况,扼要报道了天津大学在膜分主耦合式酶解反应器方面所取得的开发进展。     

有机相中壳聚糖-海藻酸固定化脂酶的特性

研究了壳聚糖 海藻酸固定化脂酶在有机相反应中的稳定性与活性。考察了凝胶时间、壳聚糖浓度及壳聚糖分子质量对固定化脂酶包埋率与活性的影响 ,确定了适宜 pH值与批反应时间。同时讨论了溶剂极性和操作时间对固定化酶稳定性的影响。测定了固定化脂酶水解橄榄油反应的动力学参数。结果表明 ,壳聚糖 海藻酸聚电解质膜可提高固定化酶的包埋率与稳定性     

乳状液膜包酶制备6-APA的研究

Production of 6-aminopenicillanic acid (6-APA) by hydrolysis using penicillin acylase (PA) was studied as a model of an enzymatic emulsion liquid membrane (ELM) process. The loss of PA activity was examined for various membrane compositions (organic solvent, surfactant, carrier). The effects of some experimental variables on the stability of emulsion were investigated. It was found that the choice of organic solvent greatly affected tilestability of the emulsion. Increasing the concentration of the carrier in the membrane phase increases the transfer rate of substrate and products but also has a destabilizing effect on the emulsion. The recovery of 6-APA obtained by a di-carrier system (N263-N1923) was much higher than those when either of the di-carriers was used separately.The whole process was controlled both by the enzymatic reaction rate and by the transfer rate of the substrate and the products, however, the ratio of them could be changed by varying the composition of the system. For an optimum condition, it was obtained that the recovery ratio of 6-APA was over 80% and the conversion of benzyl penicillin (PG) was up to 90% in the external phase after 30 minutes. Meanwhile, the breakage percentage of the emulsion was less than 2%.     

酶膜反应器的应用及展望

概述了酶膜反应器的研究现状 ,区别于传统反应器的优点 ,按照其不同特征进行分类。重点介绍其生物应用实例 ,并指明有待解决的问题和发展空间     

Effects of Additives on the Activity and Enantioselectivity of Candida rugosa Lipase in a Biphasic Medium

The effects of Li⁺, Na⁺, K⁺, Mg²⁺ and Zn²⁺ ions on the activity and enantioselectivity of Candida rugosa lipase (CRL) were investigated in a biphasic medium composed of phosphate buffer solution (containing a metal ion within a 50–500 mM concentration range) and isooctane. The hydrolytic activities of CRL towards p‐nitrophenyl acetate were measured after incubation of the enzyme in the presence of metal ions for 24 h, and they were compared to that obtained after incubation in the absence of any metal ion. The CRL activity was stimulated by the chloride salts of Li⁺, K⁺ and Mg²⁺ for all concentrations considered and the highest enhancement was achieved by Li⁺ with a 1.24–1.75 fold increase observed. The effects of metal ions on the enantioselectivity of CRL were investigated by performing the hydrolysis of racemic Naproxen methyl ester in the same biphasic medium containing Li⁺, Na⁺, K⁺, Mg²⁺ and Zn²⁺ ions. The addition of metal ions increased the hydrolysis rate by ca. 1.31–1.45 fold relative to the control, whereas the enantiomeric excess of product increased slightly in the presence of the metal ions. The effect of Triton X‐100 on the activity and enantioselectivity of the CRL was also investigated by employing 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 mM concentrations of it in phosphate buffer solution of the biphasic medium. High concentrations of Triton X‐100 stimulated the enzyme activity up to 1.66 fold after 24 h incubation. Triton X‐100 increased the hydrolysis rate almost independently of the concentration.     

Li_2O·MnO_2-Ag-YSZ氧泵型反应器中NEMCA效应的研究

本文对Ｌｉ２Ｏ·ＭｎＯ２－Ａｇ－ＹＳＺ氧泵型催化膜反应器中甲烷氧化偶联反应的ＮＥＭＣＡ效应进行了研究。考察了稳态电流和反应温度对ＮＥＭＣＡ效应的影响,考察了反应气中甲烷含量、反应温度对发生ＮＥＭＣＡ效应时的交换电流密度的影响,比较了传递体系和联合体系的交换电流密度与活性过电位的关系。结果表明：高甲烷含量、低反应温度和反应气中引入极少量的Ｏ２,可降低三相界面的交换电流密度,有利于ＮＥＭＣＡ效应的发生     

丙烯腈尾气流向变换催化燃烧的实验研究

在固定床反应器中利用HPA型催化剂进行了丙烯腈尾气流向变换催化燃烧实验。考察了在不同尾气组成、不同空速及不同换向周期下流向变换催化燃烧反应系统的热波特性、可燃物的转化率等特性。结果表明,在广泛的操作条件变化范围内,可燃物的转化率均能维持在96％以上,即使空速、气体组成在一定范围内短期波动,流向变换催化燃烧反应系统仍然能够维持正常操作,但在可燃物浓度较低且空速、换向周期与可燃物浓度匹配不合理时反应系统将熄火,浓度较高时将飞温。     

固定床催化反应器参数敏感性的研究进展

对于在固定床催化反应器中进行的强放热反应,当初始条件达到或超过某一限度时,反应系统瞬是产生的热量超过了反应系统本身所能承受的限度或负荷,造成热点温度急剧升高,导致反应系统失去控制,对反应的转化率、选择性以及催化 活性和寿命等都有不良影响。对反应系统参数敏感性的研究,实质上就是从理论上揭示出反应系统安全操作上限,使之由于温度升高引起不良后果有在反应器的设计中和操作前就能避免。文中对上述问题进行了详尽     

Marked Enhancement of the Methane Dehydrocondensation Toward Benzene Using Effective Pd Catalytic Membrane Reactor with Mo/ZSM-5

Steady state product formation rates of benzene, hydrogen, naphthalene, toluene in methane dehydrocondensation reaction on 3wt% Mo loaded ZSM-5 catalyst was enhanced 2–10 times by the removal of hydrogen using Pd membrane for 100h at 883K. The amount of permeated hydrogen through the Pd membrane was measured before and during the methane dehydrocondensation reaction. About 50–60% of hydrogen from the total hydrogen produced during the methane dehydrocondensation was selectively removed by the Pd membrane, owing to which the equilibrium of the methane dehydrocondensation was shifted toward the product side.     

无机膜催化反应的研究进展

综述了无机膜材料及无机膜反应研究的历史、现状及进展,介绍了无机膜反应器的特点与结构,阐述了无机膜催化反应在改造传统产业,合理利用资源,调整能源结构及环境保护中的重要意义,并对我国在无机膜催化反应中的发展方向进行了展望。     

酶膜反应器控制系统的研制

提出了实现连续酶化反应的控制方案,利用单片机实时检测反应所需温度、pH值和体积,实现自动控制以满足连续酶化反应的要求。试验结果表明转化率和产物的产率均得到提高,该方法具有推广价值。     

Mathematical Modeling and Optimization of Combined Steam and Dry Reforming of Methane Process in Catalytic Fluidized Bed Membrane Reactor

Mathematical modeling of the methane-combined reforming process (steam methane reforming–dry reforming methane) was performed in a fluidized bed membrane reactor. The model characterizes multiple phases and regions considering low-density phase, high-density phase, membrane, and free board regions that allow study of reactor performance. It is demonstrated that the combined effect of membrane and reaction coupling provides opportunities to overcome equilibrium limits and helps to achieve higher conversion. Additionally, the influence of key parameters on reactor performance including reactor temperature, reactor pressure, steam to methane feed ratio (S/C), and carbon dioxide to methane feed ratio (CO₂/C) were investigated in the multi-objective genetic algorithm to find the optimal operating conditions. Finally, the process of steam reforming was simulated in selected optimal conditions and the results are compared to those of the combined reforming process. Comparison reveals the superiority of the combined reforming process in terms of methane conversion, catalyst activity, and outlet H₂/CO ratio in the syngas product in being close to unity.     

Dispersion and Mass Transfer Effects on the Performance of an Immobilized Lipase Packed Bed Reactor During the Hydrolysis of Rice Bran Oil

The performance of an immobilized packed bed reactor for the hydrolysis of rice bran oil has been investigated and can be well described by a dispersion model with an average standard deviation of 0.0388. Global mass transfer coefficients estimated using the model and experimental data ranged from 0.095‐0.482 min^?1, depending on substrate flow rates. A dimensionless mass transfer correlation between the Sherwood number and the Reynolds number was obtained as NSh = 3.96 ×NRe^2.07.     

用多孔金属—SiO2复合膜反应器进行CO水蒸汽变换反应

用自制的多孔金属－ＳｉＯ２复合膜组装成一种新颖的膜反应器,利用ＣＯ变换反应考察该膜反应器的性能实验系统地考察了反应温度,空速、水／气比和只发气流量对ＣＯ转化率的影响。结果表明,在相同的反应条件下,膜反应器的转化率比固定床反应器的转化率提高４－１１％左右,最高可达２０％。     

Simulation of Catalytic Combustion of Methane in a Monolith Honeycomb Reactor

1 INTRODUCTION Monolith honeycomb reactor plays an important role in catalytic combustion[1] such as combustion chambers for gas turbines used in power generation where methane is the main reactant. It contains hun-dreds of parallel channels that are often of the order of 1—2mm in diameter. The catalyst may be dispersed within a washcoat that is coated onto the surface of the channels[2] where catalytic combustion occurs. Com-pared to conventional gas-phase combustion, catalytic combusti…     

一种选择性拆分布洛芬对映体的固定化脂肪酶

为了提高扩展青霉TS414脂肪酶(PEL)对布洛芬的拆分效率,建立了适于非水相中选择性拆分(R,S)-布洛芬的固定化方法. 结果表明,固定化介质的类型、冻干pH和外加水量等因素对固定化PEL酶促拆分(R,S)-布洛芬有较大影响. 在冻干pH为9.0、外加水量为0、以大孔吸附树脂AB-8为固定化载体的体系中,40℃反应30 h后,拆分反应的转化率可达47%,对映体过量值eeP可达98.75%. AB-8固定化后,PEL在有机相反应体系中的分散性得到了明显改善,大幅度提高了酶促拆分反应的效率;大孔吸附树脂AB-8固定化PEL具有较高的操作稳定性,连续10批拆分反应的平均转化率在47%以上,eeP值均稳定在98%以上.