Tubular catalytic membranes

Alexeeva OK, Alexeev S.Yu., Shapir B.L., Tulskii M.N. Modified tubular catalytic membrane reactor for hydrogen production from hydrocarbons. Eds. M.D. Hampton et al. Hydrogen Materials Science and Chemistry of Metal Hydrides, 2002 Kluwer Academic Publishers, NATO Science Series 11/71, 339-347. 

Watercatox Not an established process, but a project of the Fifth Framework Program of the European Union. The purpose was to develop catalytic processes for destroying organic residues in water by wet air oxidation ( WAO).The chosen system used a tubular catalytic membrane reactor for contacting the aqueous solution with air. Several companies and research institutes participated in this project from 2000, and the process was piloted with several real industrial liquid effluents. 

Akyurtlu etal. (1988) carried out a theoretical investigation on multi-phase porous tubular catalytic membrane with the liquid phase on the external side and the gas phase in the membrane tube lumen. They showed the importance of the Tliiele modulus on the reactor performance and that thin-walled catalyst tubes have larger effectiveness factors. 

The research group coordinated by Professor Gabriele Centi prepared a series of tubular catalytic membranes (TCM) and tested in the direct synthesis of H202. " Such TCMs are asymmetric a-alumina mesoporous... 

Figure 13.3 Scheme of a catalytic membrane with a cylindrical geometry (tubular or hollow fiber). 

The Hrst type of generic model for shell-and-tube membrane reactors refers to a nonisothermal packed-bed catalytic membrane tubular reactor (PBCMTR) whose cross-sectional view is shown in Figure lO.l. Mathematical models for this type of membrane reactor have been reviewed quite extensively by Tsotsis et al. [1993b]. 

General Models Describing Transport Phenomena in Packed-Bed Catalytic Membrane Tubular Reactors... 

Catalytic Membrane Tubular Reactor with Packed Bed on... 

Tsotsis et al. [1992] considered a case where two reaction zones exist in a porous membrane reactor one inside the membrane matrix and the other in the tubular region which is packed with catalyst particles. They presented a packed-bed catalytic membrane tubular reactor model under isothermal and co-current flow conditions. Thus, Equations (10-37), (10-6) and (10-45) ail reduce to the condition... 

Some other unceitainties associated with packed-bed catalytic membrane reactors arc the following. The reaction rate in the membrane layer is not easy to assess and it is likely to be different from that in the catalyst bed. The extremely small thickness of the membrane layer compared to the dimensions in the tubular and the annular regions makes the direct determination of the membrane-related parameters difficult, if not impossible in some cases. Furthermore, obtaining accurate data of the effective diffusivity for the membrane, particularly in the presence of a support layer, is not straightforward and often involves a high degree of uncertainty. 

Catalytic membrane reactors represent the most compact and yet challenging membrane reactor design. The membrane material may be inherently catalytic or rendered catalytic by impregnating a catalyst on the surface of the membrane itself or the pores inside the membrane/support matrix. When the inner tube of a shell-and-tul reactor is a permselective and also catalytic membrane, the reactor is called catalytic membrane tubular reactor. Under this special circumstance, ibj = 0 = kf for Equations (10-36) to (10-37) and (10-44) to (10-45), assuming plug flows on both the tube and shell sides. The transport equations for the membrane zone. Equations (10-5) to (10-6), hold. 

In the above examples of catalytic membrane tubular reactors (CMTR), the transport equations for the catalytic membrane zone (i.e.. Equations (10-5) and (10-6)) are considered and solved. A simpler and less rigorous approach to modeling a CMTR is to neglect the membrane layer(s) and account for the catalytic reactions in the tube core or annular region. This approach was adopted by Wang and Lin [1995] in their modeling of a shell-and-tubc reactor with the membrane tube made of a dense oxide membrane (a... 

The idea to limit polarization and fouling during tangential filtration of biological fluid by fluidizing small inert particles inside a tubular ceramic membrane had been presented at the end of the 1980s [25]. More recently, based on advances in the development of more stable membranes with increased permeance, the possibilities for integrating membranes into gas catalytic reactors to achieve a major increase in... 

Catalytically active supported ionic liquid membranes were used for propylene/propane vapor mixture separation. In this case, the ionic Hquid was immobilized in the pores of an asymmetric ceramic support, displaying sufficient permeability, good selectivity, and long-term stabUity [51]. Porous inorganic membranes were also used as a support for chiral-selective liquid membranes. For this purpose, porous tubular ceramic membranes were impregnated with 3-cyclodextrin polymer. Such SLMs were used for separation of enantiomers of racemic pharmaceutical chlorthahdone [52]. 

The first relevant modeling effort we are familiar with is a simulation study by Gill et al [5.1], who in 1975 developed a model for a wall-catalyzed porous tubular reactor. The papers by Itoh [5.2] and Sun and Khang [5.3], published in the eighties, are among the earliest studies explicitly dealing with the modelling of catalytic membrane reactors. Itoh... 

Membrane bioreactors have been modelled using approaches that have proven successful in the more conventional catalytic membrane reactor applications. The simplest membrane bioreactor system, as noted in Chapter 4, consists of two separate units, a bioreactor (typically a well-stirred batch reactor) coupled with an external hollow fiber or tubular or flat membrane module. These reactors have been modelled by coupling the classical equations of stirred tank reactors with the mathematical expressions describing membrane permeation. What makes this type of modelling unique is the complexity of the mecha-... 

Another class of processes where it is advantageous to keep the reactants separated from each other, except within the catalyst pores, is oxidation of light gaseous hydrocarbons (e.g., ethene, propene, butene). Conventionally these processes are carried out in multi-tubular fixed-bed reactors (see, for example, Fig. 20). Flammability considerations usually restrict the feed mixture composition. By adopting the concept of a multi-tubular cooled catalytic membrane reactor (with inclusion of heat pipes ), with reactants kept separate, we should be able to avoid any flammability constraints. 

M. Reif, Tubular inorganic catalytic membrane reactors Advantages and performance in multiphase hydrogenation reactions, Catal. Today 2003, 79-80, 139-149. 

A catalytic membrane reactor having a tubular ceramic membrane for H2S decomposition was patented by Vizoso [76]. It was claimed that applying a membrane reactor between 400 and 7(X)°C, with the molybdenum sulphide catalyst deposited directly on the surface of the ceramic membrane, resulted in a 20% increase in the conversion of a 4% H2S stream, though few details were provided. 

L. Paturzo, F. Gallucci, A. Basile, G. Vitulli and P. Pertid, An Ru-based catalytic membrane reactor for dry reforming of methane-its catalytic performance compared with tubular packed bed reactors, Catal. Today, 2003, 82, 57-65. 

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