Journal of Membrane Science, Vol.472, 222-231, 2014
Composite ionic liquid-polymer-catalyst membranes for reactive separation of hydrogen from carbon monoxide
Novel composite ionic liquid and polyimide membranes with dissolved RuCI3 catalyst for H-2/CO reactive separation were fabricated to combine gas diffusive separation and water-gas shift reaction. The CO concentration in the membranes is reduced via its reaction with H2O to form CO2 and H-2, catalysed by the Ru carbonyl complex which forms in the reaction between dissolved RuCI3 and CO. In order to optimize the membrane configurations and operating conditions, water-gas shift reaction turnover frequencies (TOFs) of the membranes with various concentrations of ionic liquid and RuCI3 were determined at different pressures, temperatures and times-on-stream on a purpose-built test rig. The results show that the ionic liquid, [C(4)mim][OTf] improves TOFs by increasing the solubilities of H2O and the gases solubilities within the membrane. TOFs were found to increase initially, but reduce as time-on-stream increased, due to the formation and subsequent evaporation of a Ru carbonyl complex. Lower temperature and lower concentration of [C(4)mim][OTf] were found to minimize the loss of the catalyst. It is suggested that the 2 wt% RuCl3 center dot XH2O + 20 wt% [C(4)mim][OTf] + Pl membrane operated at 140 degrees C and 2 bar has the best combination of reactivity and durability. (C) 2014 Elsevier B.V. All rights reserved.