Sorption enhanced reaction for high purity products in reversible reactions

Reversible reactions (A + B = C + D) can be performed to near completion using an admixture of catalyst and sorbent that will selectively adsorb one of the reaction products. For an initially clean sorbent and a favorable adsorption isotherm and a long reactor, the adsorbed product, C, will propagate as a sharp, shock‐like front. While the adsorbed product will not move faster than this front, the second, nonadsorbed product, D, will, in principle, leave the reactor, uncontaminated. However, a parametric analysis of the two examples presented in this work, the water gas shift and the cracking of hydrogen sulfide, reveals an unexpectedly complex behavior. While assuming adsorption equilibrium the effect of the equilibrium constant, the reaction kinetics and adsorption isotherm on the reactant and product concentration profiles are simulated. It is found that desired behavior is favored by large equilibrium constants, rapid kinetics, and strong nonlinear adsorption. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5452–5461, 2017