Sorption enhanced steam reforming of methanol for high-purity hydrogen production over Cu-MgO/Al2O3 bifunctional catalysts.

• Cu-MgO/Al 2 O 3 bifunctional catalysts exhibit superior activity and stability in SESRM. • The incorporation of Cu2+ into MgO promotes CO 2 sorption and desorption capacity. • MgO facilitates the production of formate and consequent reduction of CO. • Cu sintering can be inhabited due to the strong interaction between Cu and MgO. Sorption enhanced steam reforming of methanol (SESRM) can significantly promote the hydrogen production process with simultaneous CO 2 sorption. The mechanical mixture of catalysts and sorbents as a conventional approach is complex and requires high temperatures for regeneration, which results in serious sintering of Cu-based catalysts. This paper describes a novel Cu-MgO/Al 2 O 3 bifunctional catalysts (x CMA, x is denoted as the mass fraction of Cu, 0%–10%) via a sol–gel method for the SESRM process. We find that Cu species, including metallic Cu and Cu ions, co-exist on the catalyst. The metallic Cu on the catalyst surface is an active site for methanol steam reforming while the Cu ion in MgO lattice promotes the CO 2 sorption capacity. Moreover, the incorporation of Cu ion into MgO also facilitates CO 2 desorption by forming more bidentate carbonates. Due to the strong interaction between Cu and MgO, the Cu sintering is inhabited in comparison with the mechanical mixture of catalysts and sorbents. Meanwhile, MgO is found to induce more formate species to inhibit the generation of carbon monoxide. As a result, the optimal bifunctional catalyst, 8 wt% Cu-MgO/Al 2 O 3 (8CMA) shows a superior performance in both catalytic reforming and CO 2 sorption with a highest H 2 selectivity of 99.3% and lowest CO selectivity (<0.15%) over 10 repeated cycles. This study suggests that the appropriate control of bifunctional catalysts can lead to powerful potential for high H 2 production performance in SESRM. [ABSTRACT FROM AUTHOR]