Kinetic and structural requirements for a CO2 adsorbent in sorption enhanced catalytic reforming of methane. Part I: Reaction kinetics and sorbent capacity

Abstract This paper presents a fundamental model-based analysis for the applicability of integration of a highly active Rh/Ce α Zr 1−α O 2 catalyst with two candidate CO 2 sorbents for pure H 2 production in low temperature sorption-enhanced steam reforming of methane. K-promoted hydrotalcite and lithium zirconate solids are considered in the investigation as CO 2 sorbents. The process is analyzed using multi-scale modeling levels of a heterogeneous particle-based model, a heterogeneous bulk-scale model, and a homogenous bulk-scale model. The presence of this active catalyst dictates strict requirements on the sorbent in terms of fast adsorption kinetics for an efficient process performance. The maximum CH 4 conversion enhancement is determined to be a strong function of sorption kinetics. This enhancement is not affected by a higher sorbent capacity at slow adsorption kinetics. The process is studied using two fixed bed configurations of an integrated dual function particle and an admixture bed of catalyst/sorbent particles. Optimal operating conditions for the hydrotalcite-based system are identified to provide CH 4 conversion of 98% with high H 2 purity of 99.8% and low CO 2 contamination ( 4 conversion and H 2 purity of 99.9% at identical conditions. Based on the end application of H 2 produced, the process can be tuned to feed gas turbine cycles, fuel cells, or petrochemical plants.