Zeolite membrane reactors modelling

Modeling on the reactor level, which is needed in designing the zeolite membrane reactor, could receive some more attention, since the number of studies in this particular field are few [56,106]. 

Jeong BH, Sotowa KI, and Kusakabe K. Modeling of an FAU-type zeolite membrane reactor for the catalytic dehydrogenation of cyclohexane. Chem Eng J 2004 103 69-75. 

Membrane reactors provide opportunities for overcoming thermodynamic limits on the maximum attainable conversion of reversible reactions. A simple membrane reactor model has been employed to investigate the performance of Cs/C6 hydroisomerization process on zeolites and compare it to a state-of-the-art total isomerization (TIP) process. A RON of 88.0 was obtained, slightly higher and promising compared to the TIP process with RON of 86. 

Casanave D et al (1999) Zeolite membrane reactor for isobutene dehydrogenation experimental results and theoretical modeling. Chem Eng Sci 54 2807-2815... 

To this end, I invited an international team of highly expert scientists from the field of membrane science and technology to write about the state-of-the-art of the various kinds of membranes (polymeric, Pd- and non-Pd-based, carbon, zeolite, perovskite, composite, ceramic and so on) used in membrane reactors, modelling aspects related to all kinds of membrane reactors, the various applications of membrane reactors and, finally, economic aspects. 

Casanave, D., Ciavarella, R, Fiaty, K. and Dalmon, J.A. (1999) Zeolite membrane reactor for isobutane dehydrogenation Experimental results and theoretical modelling. Chemical Engineering Science, 54, 2807-2815. 

F. Kapteijn, W. Zhu, J.A. Moulijn, T.Q. Gardner, Zeolite Membranes - Modelling, Application. In A. Cybulski J.A. Moulijn (Eds), Structured Catalysts and Reactors Second Edition, Revised and Expanded. Marcel Dekker, New York, NY, 2005. 

Tanaka et al. (2001) used zeolite T membranes in an ISU membrane reactor (at 343 K). Almost complete conversion was reached. The reaction time courses were well described by a model based on two assumptions (1) the reaction obeyed to a second-order kinetic and (2) the permeation flux of each component was proportional to its concentration. 

Daramola M O, Burger A J and Giroir-Fendler A (2011), Modelling and sensitivity analysis of a nanocomposite MFI-alumina based extractor-type zeolite catalytic membrane reactor for m-Xylene isomerization over Pt-HZSM-5 catalyst , Chem Eng J, 171,618-627. 

Langhendries et al [5.74] analyzed the liquid phase catalytic oxidation of cyclohexane in a PBMR, using a simple tank-in-series approximate model for the PBMR. In their -reactor the liquid hydrocarbon was fed in the tubeside, where a packed bed of a zeolite supported iron-pthalocyanine catalysts was placed. The oxidant (aqueous butyl-hydroperoxide) was fed in the shellside from were it was extracted continuously to the tubeside by a microporous membrane. The simulation results show that the PBMR is more efficient than a co-feed PBR in terms of conversion but only at low space times (shorter reactors). A significant enhancement of the organic peroxide efficiency, defined as the amount of oxidant used for the conversion of cyclohexane to the total oxidant converted, was also observed for the PBMR. It was explained to be the result of the controlled addition of the peroxide, which gives low and nearly uniform concentration along the reactor length. 

Yawalkar et al. (2001) has developed a model for a three-phase reactor based on the use of a dense polymeric composite membrane containing discrete cubic zeolite particles (Fig. 4.5) for the epoxidation reaction of alkene. Catalytic particles of the same size are assumed vdth a cubic shape and uniformly dispersed across the polymer membrane cross-section. Effects of various parameters, such as peroxide and alkene concentration in liquid phase, sorption coefficient of the membrane for peroxide and alkene, membrane-catalyst distribution coefficient for peroxide and alkene and catalyst loading, have been studied. The results have been discussed in terms of a peroxide effidency defined as the ratio of flux of peroxide through the membrane utilized for alkene oxidation to the total flux of organic peroxide through the membrane. The paper aimed to show that, by using an organophilic dense membrane and the catalysts confined in the polymeric matrix, the oxidant concentration (in that reaction peroxides) can be controlled on the active site with an improvement of the peroxide efficiency and selectivity to desired products. 

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