CMR catalytic membrane reactor

Note C=conversion, selectivity, K=yield, subscript m denotes the maximum value, subscript e indicates the equilibrium value without membrane, CMR=catalytic membrane reactor, /MRCF=catalytic ly inert membrane with catalyst pellets on the feed side... 

In the case of a catalytic membrane reactor (CMR), the membrane is (made) intrinsically catalytically active. This can be done by using the intrinsic catalytic properties of the zeolite or by making the membrane catalytically active. When an active phase is deposited on top of a membrane layer, this is also called a CMR because this becomes part of the composite membrane. In addition to the catalytic activity of the membrane, a catalyst bed can be present (PBCMR). The advantages of a CMR are as follows ... 

One of the most studied applications of Catalytic Membrane Reactors (CMRs) is the dehydrogenation of alkanes. For this reaction, in conventional reactors and under classical conditions, the conversion is controlled by thermodynamics and high temperatures are required leading to a rapid catalyst deactivation and expensive operative costs In a CMR, the selective removal of hydrogen from the reaction zone through a permselective membrane will favour the conversion and then allow higher olefin yields when compared to conventional (nonmembrane) reactors [1-3]... 

A catalytic membrane reactor (CMR) presents an alternate configuration where the membrane is both catalytically active and permselective. The reactant conver-... 

Besides previously described examples of integrated membrane systems and much more reported in the literature, including applications in gas separation and the petrochemical industry [29], a special case of integrated or hybrid membrane systems, with a lot of interest in the logic of the sustainable growth, is represented by the catalytic membranes reactors (CMRs). 

Catalytic membrane reactors (CMRs) are reactors which couple, in the same unit, a conversion effect (catalyst) and a separation effect (membrane). These reactors, besides the obvious interest of concentrating two classical steps of chemical processes in the same unit, have already shown various potential benefits for a range of reactions, and the concept of CMRs is a matter of continuous investigation for a large number of applications. 

Various arrangements have been proposed to combine a catalyst and a membrane to give the catalytic membrane reactor (CMR). Figure 5 schematically represents the most frequently used types of arrangement. 

Figure 9.6 Total conversion for inert membrane reactor with catalyst on the feed side (IMRCF), catalytic membrane reactor (CMR) and conventional fixed-bed reactor (FBR) with uniform and Dirac delta catalyst activity distributions as a function of the dimensionless residence time [Yeung et al., 1994]...

Besides total conversion, other reaction performance index may benefit from optimizing the catalyst distribution and location. Examples are product purity on the feed or p>ermeate side and product molar Row rate on the feed or permeate side. Yeung et al. [1994] have also investigated these aspects and provided comparisons among IMRCF, FBR and catalytic membrane reactor (CMR) in Figure 9.8. It is apparent that the various reaction performance indices call for different optimal catalyst distributions. 

In the second mode of incorporating a catalyst into a membrane reactor, the catalyst is attached to the membrane surface on the feed or permeate side or to the surfaces of the membrane pores. This case and the third mode where the membrane is inherently catalytic are often called catalytic membrane reactor (CMR). 

Two of the main types of catalytic membrane reactors are shown in Fti, me 4-12, The reactor in the middle is called an inert membrane reactor ivi/ i catalyst pellets on the feed side (IMRCF). Here the membrane is inert 8i..1 serves as a batrier to the reactants and some of the products. The reactor on ih bottom is a catalytic membrane reactor (CMR). The catalyst is deposiid directly on the membrane and only specific reaction products are able to e it the permeate side. For example, in the reversible reaction... 

The different types of membrane reactor configurations can also be classified according to the relative placement of the two most important elements of this technology the membrane and the catalyst. Three main configurations can be considered (Figure 25.13) the catalyst is physically separated from the membrane the catalyst is dispersed in the membrane or the membrane is inherently catalytic. The first configuration is often called the inert membrane reactor (IMR), in contrast to the two other ones, which are catalytic membrane reactors (CMRs).5o... 

Inert membrane reactors (IMRs) Catalytic membrane reactors (CMRs)... 

Catalytic membrane reactors (CMRs) are an interesting example of integrated system in which molecular separation and chemical conversions are combined in one step [8]. The heterogenization of catalysts in membrane is particularly suitable for catalyst design at the atomic and molecular... 

The most commonly utilized catalytic membrane reactor is the PBMR, in which the membrane provides only the separation function. The reaction function is provided (in catalytic applications) by a packed-bed of catalyst particles placed in the interior or exterior membrane volumes. In the CMR configuration the membrane provides simultaneously the separation and reaction functions. To accomplish this, one could use either an intrinsically catalytic membrane (e.g., zeolite or metallic membrane) or a membrane that has been made catalytic through activation, by introducing catalytic sites by either impregnation or ion exchange. This process concept is finding wider acceptance in the membrane bioreactor area, rather than with the high temperature catalytic reactors. In the latter case, the potential for the catalytic membrane to deactivate and, as a result, to require sub-... 

In comparison, catalytic membrane reactors (CMRs) based upon OTM technology integrate oxygen separation from the atmosphere and hydrocarbon processing into a single exothermic step (see Fig. 7.1) ... 

Figure 7.11 Schematic of how OTM based catalytic membrane reactors (CMRs) and hydrogen transport membranes (Hj MBN) might facilitate an environmentally benign electric utility.

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