Simulation of a Palladium Membrane Reactor for Dehydrogenation of Ethylbenzene.

Abstract

Mathematical models taking into account the non-isothermal condition and radial heat and mass transfer for the dehydrogenation of ethylbenzene to styrene in a conventional fixed-bed reactor and a palladium membrane reactor were developed using the kinetic data of a 70 wt% F 2 O 3 :20 wt% K 2 O:5 wt% Ce 2 O:5 wt% Cr 2 O 3 catalyst and the H 2 permeation data through a palladium membrane with 10 µ µ µ µ µm thickness. The study showed that due to the continuous removal of H 2 from the reaction side, both the conversion and the selectivity obtained from the membrane reactor were superior to those of the conventional fixed-bed reactor. It was shown by the theoretical study that the assumptions of isothermal and plug-flow conditions overestimated the performance of the reactors. The membrane reactor with a catalyst packed in the shell side showed superior performance to the one with a catalyst packed in the tube side because the former had lower heat transfer resistance than the latter. The operating modes in the separation side played an important role in determining the reactor performance. The use of reactive sweep gas did not only rapidly consume the permeating H 2 but also supplied additional heat to the reaction side; however, the resulting performance may be interior to the other operating modes such as vacuum and inert sweep gas modes.

Maximum Production Minimum Pollution (MPMP), Necessary but not Sufficient for Sustainability

“…The numerical values of Ai and Ei are given in Table 1 and are used to calculate the rate of reactions in kmol/kg cat/h. To change the units of partial pressures from bars to Pascal and the reaction rates from kmol/kg cat/h to mol/kgcat/s, the above rate equations have to be multiplied by the constants in Table 2 (Amon et al, 1999;Shu et al, 1994;Carl, 1999;Assabumrungrat et al, 2002;Bischoff, 1990;Villadsen and Michelsen, 1978;Trefethen, 2000). On the tube side, the hydrogenation reaction of nitrobenzene to aniline is given by (Amon et al, 1999):…”

Simulation Investigation of Novel Membrane Reactors for Catalytic Reactions

“…The membrane tube is considered to be a composite wall having a stainless steel layer coated by a thin layer of palladium. The thermal conductivities of the stainless steal layer and the palladium are taken to be 24.5 W/m×K and 93.3 W/m×K, average values over a temperature range of 200-1800 K. 9,10 The heat transferred per unit length from each tube is obtained from:…”

An efficient palladium membrane reactor to increase the yield of styrene in ethylbenzene dehydrogenation

“…alumina, titania, zirconia, or vycor glass), and composite membranes (e.g. metal/alumina, metal/vycor glass, or metal/stainless steel [21][22][23][24][25]). Although suffering from relatively high cost, dense palladium membranes have been received most attention due to its exclusive hydrogen permeability characteristics.…”