Integrated Capture and Conversion of CO_2 to Methanol in a Post-Combustion Capture Solvent: Heterogeneous Catalysts for Selective C-N Bond Cleavage

摘要

An efficient and selective heterogeneous catalyst is identified for the condensed-phase hydrogenation of captured CO_2 in the presence of an advancedwater-lean post-combustion capture solvent, (N-(2-EthoxyEthyl)-3-MorpholinoPropan-1-Amine), 2-EEMPA. The catalysts commonly used for gasphaseCO_2 hydrogenation (e.g., Cu/Zn/Al_2O_3) cause deactivation of aminepromoters via N-methylation by C-O cleavage of formamide intermediates.A heterogeneous catalyst system that suppresses N-methylation of aminesolvents is identified, demonstrating how Pt, supported by reducible metaloxides CeO_2 or TiO_2, can be selective for C-N cleavage to produce methanol.This is the first known demonstration of integrated low-temperature thermocatalyticcapture and conversion of CO_2 to methanol in an economicallyviable CO_2 capture solvent. Technoeconomic analyses performed on the stateof-technology suggest that methanol can be produced with a minimum sellingprice of $4.4/gallon ($1,460/metric ton) when using CO_2 captured from a 650MW natural gas combined cycle plant. Ultimately, a road map of how realisticand achievable improvements to space velocity and methanol selectivity ofthis integrated process can enable near cost parity to fossil-derived methanol,with a selling price of ≈$1.4/gal ($470/metric ton), is presented.