Catalytic conversion of carbon dioxide (CO2) to fuels or chemicals is a “Holy Grail” paradigm.1–4 Unfortunately, only a few industrial processes employ CO2 as a building block, such as the production of urea, salicylic acid and polycarbonates.5 Recently, increasing efforts have been devoted to the transformation of CO2 into a variety of value-added chemicals including methane, methanol, formaldehyde, formic acid, and organic carbonates. Among them, formic acid is the important commodity chemical used in food industry as well as for leather tanning.6 Moreover, formic acid or formate salts is highly attractive as the clean source for H2 generation. However, since CO2 is the lowest in energy of all carbon-containing binary neutral species, the direct hydrogenation of CO2 in gas-phase is thermodynamically unfavorable and implies high external energy inputs.7,8 One approach to overcome the thermodynamic limitation for CO2 hydrogenation is to use base additives such as ammonia or amines in aqueous phase and convert CO2 to water soluble bicarbonate salts. In fact, aqueous amine or ammonia solvents are widely used in carbon capture and storage processes (CCS).9,10 With the deployment of large-scale CCS facilities, it is expected that aqueous amine or ammonia captured CO2, in the form of bicarbonate/carbonate ions, can be directly used as C1 feedstocks for chemical production at a low or even negative cost due to saving parasitic costs of CO2 separation and storage in CCS processes. Herein, we investigate the catalytic process to convert amine-CO2 adducts to formic acid with supported palladium metal nano-cluster catalysts in aqueous media. To design the stable heterogeneous catalytic system for this reaction, we aim to directly convert the amine-CO2 adducts from the CO2 capture step of CCS process to formic acid, saving the energy and cost for separating, compressing, and transporting CO2 in the storage step of CCS process. In this study, we prove that the CO2 capture and conversion process is feasible via the aqueous phase hydrogenation of amine-CO2 adducts. Active carbon supported Pd nanoparticle catalyst shows the best performance among the tested supported metal catalysts. The effects of amine structure, structure, solubility, functional group containing, and other proprieties are pronounced on the conversion of amine-CO2 adducts. The yield of formates is highly dependent on the bicarbonate and carbamate intermediates in an amine-CO2 adducts.

High efficient formate production by low temperature hydrogenation of amine captured CO2 over Pd catalyst

249th National Meeting (2015)

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