Catalytic hydrothermal conversion of CO2 captured by ammonia into formate using aluminum-sourced hydrogen at mild reaction conditions

[Display omitted] •Ammonium carbamate showed the best performance toward formate (38%) under mild reaction temperature.•Yield was proportional to catalyst content up to 30% of Pd/C with respect to carbon source.•Aluminum was partially active up to the 5th re-use.•Pd can play a reducing role through the formation of palladium hydride species.•Al showed comparable yield to gaseous H2 at similar level of pressure. The catalytic conversion of CO2 captured in aqueous media into formate was studied using aluminum-sourced hydrogen in a batch reaction system. To do so, the main ammonia-based CO2 absorption derivatives: ammonium carbamate, carbonate and bicarbonate and sodium bicarbonate were selected as CO2 source. The performance of the different species was determined under mild hydrothermal reaction conditions (120°C), using Pd/C 5wt% catalyst. In these conditions, the formate yield and selectivity increase in the order ammonium bicarbonate