Solvent- and Catalyst-Free Carbon Dioxide Capture and Reduction to Formate with Borohydride Ionic Liquid.

The metal- and solvent-free capture and reduction of large amounts of CO to formate under ambient conditions is achieved by combining a pyrrolidinium-based ionic liquid with a borohydride anion. This material demonstrates one of the highest CO capacities at room temperature and 1 bar with up to 1 g  g . CO gas reacts with the BH anion to give triformatoborohydride, [HB(OCHO) ] . The reaction occurs without loss in capacity at low CO concentration (6 vol % diluted with N ). The thermodynamics and kinetics of the reaction were monitored by using a magnetic suspended balance. In addition, more than 1 mol  mol is captured and reduced if air is used as a CO source. The product can be then treated with HCl to give formic acid and the corresponding ionic liquid chloride, which can be recycled. This ionic liquid borohydride demonstrates great potential as a CO absorber and reducer to produce alternative fuels.