Bifunctional hybrid catalysts derived from Cu/Zn-based nanoparticles for single-step dimethyl ether synthesis

Well-defined colloidal Cu/Zn-based nanoparticles were synthesized and employed as precursors for the methanol active component in bifunctional syngas-to-dimethyl ether (STD) catalysts. The experiments were conducted using simulated biomass-derived, CO-rich syngas (H-2:CO ratio of 1:1) in a single continuous-flow reactor by combining the two catalytically active components (i.e., Cu/ZnO for methanol synthesis and gamma Al2O3 for its subsequent dehydration). Two different synthetic pathways were developed for synthesizing the colloidal Cu/Zn-based nanoparticles, while ensuring close contacts between the Cu nanoparticles and the Zn phase. Pure Cu nanoparticles were used as a reference. A series of bifunctional STD catalysts was prepared, where the nanoparticles were either directly supported on the dehydration catalyst or integrated into the STD catalyst by physical mixing. With this approach, active catalysts for the STD reaction with high DME selectivity were obtained.