Ultra-low temperature water–gas shift reaction catalyzed by homogeneous Ru-complexes in a membrane reactor – membrane development and proof of concept

Abstract

A monolithic membrane reactor combining the supported ionic liquid-phase (SILP) catalyzed ultra-low temperature water–gas shift reaction (WGSR) with in situ product removal is presented. The SILP catalyst consists of the transition metal complex [Ru(CO)₃Cl₂]₂ homogeneously dissolved in 1-butyl-2,3-dimethylimidazolium chloride [C₄C₁C₁Im]Cl and supported on alumina pellets. These Ru-SILP pellets are deposited inside the channels of a silicon carbide monolith. The resulting monolithic catalyst is very active and stable in the WGSR in the temperature range between 120 and 160 °C, thereby making full use of the high equilibrium conversion at these conditions. A facilitated transport membrane was coated onto the smooth outside of the SiC monolith to allow preferential removal of CO₂ compared to H₂. The proof of this concept has been shown under industrially relevant conditions using a biogas feed. These results demonstrate, for the first time, the combination of homogeneous SILP catalyzed WGSR with enhanced in situ removal of one of the products (here: CO₂) via facilitated transport membrane separation.