Enhanced CO selectivity for reverse water‐gas shift reaction using Ti 4 O 7 ‐doped SrCe 0.9 Y 0.1 O 3‐δ hollow fibre membrane reactor

Reverse water‐gas shift reaction (RWGS) is important in the CO 2 utilization cycle to convert carbon dioxide (CO 2 ) and hydrogen (H 2 ) to carbon monoxide (CO). In this work, the RWGS performance is evaluated by utilizing Ti 4 O 7 ‐doped SrCe 0.9 Y 0.1 O 3‐δ (SCY‐b) hollow fibre membrane reactor where H 2 permeates through the SCY‐b proton conducting membrane and reacts with CO 2 feed gas. Upon increasing the temperature from 750 to 950 °C, the CO yield increased from a negligible value to 14.82 %, when the sweep gas flow rate was 50 mL min −1 H 2 ‐He (50:50 vol. ratio) and the feed gas flow rate was 100 mL min −1 CO 2 ‐N 2 (5:95 vol. ratio). The CO yield increase with the temperature increase reflects the enhanced H 2 permeation flux through the SCY‐b membrane at higher temperatures. Higher CO 2 concentration in the feed gas led to lower CO yield due to the higher amount of remaining CO 2 in the outlet stream. The deposition of porous SCY or SCY‐b surface layer onto the hollow fibre outer circumference surface also increased H 2 flux through the fibre relative to the non‐deposited one. Thermogravimetric and CO 2 ‐temperature programmed desorption results further reveal that SCY‐b adsorbed CO 2 at temperature above 500 °C due to the reaction between CO 2 and SCY‐b material. Despite the formation of SrCO 3 during RWGS, the SCY‐b hollow fibre membrane reactor still displayed a stable CO yield of around 14 % throughout the 6‐day continuous membrane reactor test.