PNNL

Abstract

We have identified an efficient and selective heterogenous catalyst for the condensed-phase hydrogenation of captured CO2 in the presence of an advanced water-lean post-combustion capture solvent, (N-(2-EthoxyEthyl)-3-MorpholinoPropan-1-Amine), 2-EEMPA. The catalysts commonly used for gas-phase CO2 hydrogenation (e.g., Cu/Zn/Al2O3) cause deactivation of amine promoters via N-methylation by C-O cleavage of formamide intermediates. Here, we identify a heterogenous catalyst system that suppresses N-methylation of amine solvents, demonstrating how Pt, supported by reducible metal oxides CeO2 and TiO2, can be selective for C–N cleavage to produce methanol. This is the first known demonstration of integrated low-temperature thermocatalytic capture and conversion of CO2 to methanol in an economically viable CO2 capture solvent. Technoeconomic analyses performed on the state-of-technology (SOT) suggests that methanol could be produced with a minimum selling price of $4.4/gallon ($1,460/metric ton) when using CO2 captured from a 650 MW natural gas combined cycle plant. Ultimately, we present a road map of how realistic and achievable improvements to space velocity and methanol selectivity of this integrated process could enable near cost parity to fossil-derived methanol, with a selling price of approximately $1.4/gal ($470/metric ton).