Influence of Ba on Co-Al-Ba composite oxide catalysts in auto-thermal reforming of acetic acid for hydrogen production

Auto-thermal reforming (ATR) of acetic acid (HAc) is one of the potential approaches to produce hydrogen. However, the current catalysts suffered from deactivation raised from sintering and carbon deposition. In order to address these concerns, a series of Co-Al-Ba composite oxide catalysts with different Ba dopings were synthesized by Pechini method, and the activity of hydrogen production via ATR of HAc was evaluated. The CAB50 catalyst with 50 wt% of BaO presented superior activity and stability: the conversion of HAc was stable at 100%, while the hydrogen yield was maintained at 2.4 mol-H 2 /mol HAc. This can be attributed to the replacement of Co by Ba in CoAl 2 O 4 spinel, hence more active species of Co 0 were exposed over the stable BaAl 2 O 4 skeleton, promoting adsorption and activation of HAc with stability. Meanwhile, the TG analysis showed that suitable amount of Ba doping promoted gasification of coking precursors and relieved carbon deposition, as also proved by the SEM. Spinel phase of CoAl 2 O 4 was prepared by Pechini method, and performed poor in auto-thermal reforming (ATR) of acetic acid (HAc) for hydrogen production, which can be attributed to constrain of spinel structure for reduction of Co oxides; As comparison, with introduction of Ba species, strong interaction of between Co and Al within the CoAl 2 O 4 spinel was specifically tuned by Ba via formation of BaAl 2 O 4 stuffed tridymite type structure, resulting in highly dispersed Co species over the BaAl 2 O 4 skeleton as active sites, and the reactivity was thus improved with high and stable hydrogen yield.