Membrane reactors comparison

S. Rissom, J. Beliczey, G. Giffels, U. Kragl, and C. Wan drey, Asymmetric reduction of acetophenone in membrane reactors comparison of oxazaborolidine and alcohol dehydrogenase, Tetrahedron Asymm. 1999, 10, 923-928. 

Kikuchi, E., Menoto, Y., Kajiwara, M., Uemiya, S., Kojima, T. (2000). Steam reforming of methane in membrane reactors comparison of electroless-plating and CVD membranes and catalyst packing methods. Catalysis Today 56, 75-81. 

Figure 12.4 Methane conversion against temperature for membrane reactor. Comparison between experimental data (symbols) and model results (lines) for a 40 SCCM sweep flow rate. Reprinted from G. Barbieri, G. Mar-igliano, E. Drioli, Simulation of steam reforming process in a catalytic membrane reactor, Ind. Eng. Chem. Res., 36, 6, 2001, with permission of American Chemical Society.

CO conversion as a function of hydrogen recovery factor (HRF) in WGS tests with a Pd membrane reactor comparison with thermodynamic (TD) equilibrium values. (After Pinacci et ai, 2010.)... 

Figure 4. Comparison of Propane Aromatization Performances of a Palladium Membrane Reactor (PMR) and a Conventional Reactor (CR) using a Ga-H-ZSM-5 Catalyst...

Kragl and Wandrey made a comparison for the asymmetric reduction of acetophenone between oxazaborolidine and alcohol dehydrogenase.[59] The oxazaborolidine catalyst was bound to a soluble polystyrene [58] and used borane as the hydrogen donor. The carbonyl reductase was combined with formate dehydrogenase to recycle the cofactor NADH which acts as the hydrogen donor. Both systems were run for a number of residence times in a continuously operated membrane reactor and were directly comparable. With the chemical system, a space-time yield of 1400 g L"1 d"1 and an ee of 94% were reached whereas for the enzymatic system the space-time yield was 88 g L 1 d"1 with an ee of >99%. The catalyst half-life times were... 

A lipase-immobilized membrane reactor was applied for the optical resolution of racemic naproxen, lipase stability was enhanced by the EMR set-up to > 200 h in comparison with a half-life of 2 h in a stirred tank. Only pure lipase gave the best enantioselectivity (Sakaki, 2001). 

A simulative comparison of dense and microporous membrane reactors for the steam reforming of methane,... 

Figure 4.34 shows the PSPS for the reactive membrane separation process with application of a Knudsen-membrane. In comparison with reactive distillation, the membrane turns the vertical hyperbola into a horizontal hyperbola. In particular, the membrane shifts the stable node branch towards the THF-vertex such that THF-rich products can be attained in the considered Knudsen-membrane reactor. 

Fig. 12.10. Comparison between experimentally determined and predicted conversions of cyclohexane in the membrane reactor (Eq. (37)) as a function of the sweep (dilution) ratio (Eq. (36)) at 473 K for three different cyclohexane feed concentrations (right, 3.7 vol% center, 4.9 vol% left, 5.8 vol%). The corresponding equilibrium conversions, Xeq, are indicated by dashed lines.

In order to interpret and further analyze the results obtained for the membrane reactor it is expedient to perform a comparison with the conventional fixed-bed reactor. Following studies conducted by Reo et al. [49, 50], the three possible configurations illustrated in Fig. 12.11 could be compared. 

Fig. 12.17. Comparison between experimental results obtained in a conventional (co-feed) fixed-bed reactor (FBR) and in a membrane reactor (MR) where the oxygen was dosed from the shell side over the membrane wall in a dead-end configuration. Conditions xo2° = 0.004 xc2H6° = 0.007 GHSV = 38 000 hr1.

Fig. 12.18. Comparison of the optimized reduced amounts that should be dosed and the corresponding internal compositions for a fixed-bed reactor (discrete dosing, top) and a membrane reactor (continuous dosing, bottom). A triangular network of parallel and series reactions was analyzed using an adapted plug-flow reactor model, Eq. 48. One stage (left) and 10 stages connected in series (right) were considered. All reaction orders were assumed to be 1, except for those with respect to the dosed component in the consecutive and parallel reactions (which were assumed to be 2) [66].

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. 

Figure 10.6 Comparison of modeling and experimental conversions of thermal decomposition of carbon dioxide in a dense zirconia membrane reactor (Itoh et al., 1993]...

Shown in Figure 10.19 is a comparison of the overall reaction rate as a function of the liquid flow rate for the three models Just mentioned [Harold et al., 1989]. Three different values of the catalytic activity (k ) arc used as a parameter. The solid line, dashed line (-) and dotted line (- -) represent the results predicted by the CNMMR model with a well-mixed liquid stream, the CNMMR model with a laminar-flow liquid stream and the string-of-pellcts reactor model, respectively. The membrane is assumed to be 0.1 cm thick for the two membrane reactors. The liquid feed is saturated with A and contains a... 

Comparison of conversion of concurrent and counter-current membrane reactors... 

Figure 11.7 Comparison of co-current and counter-current porous membrane reactors for decomposition of ammonia with a hydrogen permselectivity determined by Knudsen diffusion at 627 C [Collins ct al., 19931...

Figure 11.10. Comparison of conversions in a dense Pd membrane reactor with five different ideal flow pauems [Itoh et al., 1990]...

Comparison of performance of fluidized bed membrane reactor (FBMR), fluidized bed reactor (FBR) and continuous stirred tank reactor (CSTR)... 

Figure 11.22 Comparison of plug-flow isothermal and adiabatic palladium membrane reactors for dehydrogenation of 1-butene [Itoh and Govind, 1989]...

Figure 11.38 Comparison of single- and two-membrane reactors as a function of the ratio of the reactant permeation rale to the reaction rate [Tekid et al., 1994]...

Despite the unique properties of inorganic membranes vs. the rather well-established polymeric ones (see Table 1 for a comparison), issues such as membrane instability, insufficient permeability or permselectivity, or simply the unbearable costs implied still hamper the application of inorganic-membrane reactors in the process industry. 

Miachon S, Perez V, Crehan G, Torp EG, Raeder H, Bredesen R, and Dalmon JA. Comparison of a contactor catalytic membrane reactor with a conventional reactor Example of wet air oxidation. Catal Today 2003 82(1 ) 75-81. 

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