Multifunctionality of Cu-ZnO-ZrO2/H-ZSM5 catalysts for the one-step CO2-to-DME hydrogenation reaction

A series of Cu-ZnO-ZrO2/H-ZSM5 multifunctional catalysts for the one-step CO2-to-DME hydrogenationreaction was prepared via coprecipitation of methanol catalyst precursors by means of different precipi-tating agents (i.e., sodium bicarbonate, ammonium carbonate, oxalic acid and urea) in a slurry containingdispersed zeolite particles. The samples were characterized by XRF, XRD, N2adsorption/desorptionisotherms, SEM, N2O-titration, TPR and NH3/CO2TPD techniques, while the catalytic testing was car-ried out in a fixed-bed reactor operating at 3.0 MPa, in the TRrange 473-513 K and space velocity of10,000 h-1(CO2/H2/N2, 3/9/1). The experiments revealed that the preparation methodology significantlyaffects catalyst properties and hence catalyst activity. The multifunctional catalyst prepared via ammo-nium carbonate precipitation resulted to be the most active in CO2conversion, also accomplishing highDME selectivity, with a maximum space-time yield of 0.225 kgDME/kgcat/h. Catalyst characterization dis-closed that the strength of basic sites, the ratio between acid and basic sites along with the Cu particlesizes are crucial to achieve maximum catalytic performance, keeping CO selectivity to a minimum valueject]