Dehydrogenation reactions zeolite membrane reactors

Improved selectivity in the liquid-phase oligomerization of i-butene by extraction of a primary product (i-octene C8) in a zeolite membrane reactor (acid resin catalyst bed located on the membrane tube side) with respect to a conventional fixed-bed reactor has been reported [35]. The MFI (silicalite) membrane selectively removes the C8 product from the reaction environment, thus reducing the formation of other unwanted byproducts. Another interesting example is the isobutane (iC4) dehydrogenation carried out in an extractor-type zeolite CMR (including a Pt-based fixed-bed catalyst) in which the removal of the hydrogen allows the equilibrium limitations to be overcome [36],... 

The majority of zeolite MR applications reported in the literature to date fall into the category of PBMRs. The reactor consists of a zeolite membrane with a conventional catalyst present in the form of a packed bed of pellets. The reaction takes place in the catalyst bed while the zeolite membrane serves mainly as a product separator (for H2 or H2O separation) [27] or a reactant distributor (for O2 distribution) [28]. Figure 3.5 illustrates a FAU-type zeolite PBMR combined with a packed bed reactor for dehydrogenation of cyclohexane [29]. Half of the catalyst is packed in the area upstream of the permeation portion to enhance the conversion, otherwise cyclohexane will preferentially permeate at the front end of the zeolite membrane, resulting in a decrease in conversion. 

Other authors studied the dehydrogenation of cyclohexane to benzene" and the cis to trans isomerization of piperylene. Both reactions were carried out in a vapour phase batch reactor at low temperature with a catalytic polymeric membrane, a composite polyethylacrylate polymer built-in with zeolite 13X containing Ni or Ti" or Co as catalyst. The reactor was fed with pure reactants in both cases. The authors developed a simple transient... 

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