Experimental and theoretical study of the intrinsic kinetics for dimethyl ether synthesis from CO2 over Cu-Fe-Zr/HZSM-5

An intrinsic kinetics model was established for CO2 hydrogenation to dimethyl ether (DME) with a Cu-Fe-Zr/HZSM-5 catalyst based on H-2/CO2 adsorption, simulation, and calculation of methanol synthesis from CO2 intermediates and experimental data. H-2/CO2-temperature programmed desorption results show a dissociative H-2 adsorption on Cu site; CO2 was linearly adsorbed on Fe3O4 weak base sites of the catalyst; the adsorbing capacity of H-2 and CO2 increased after Zr-doping. Density functional theory analysis of methanol synthesis from CO2 and H-2 revealed a formate pathway. Methanol synthesis was the rate-limiting step (173.72 kJmol(-1) activation energy) of the overall CO2 hydrogenation reaction, and formation of H2CO is the rate-determining step of methanol synthesis. Relative errors between calculated and experimental data of partial pressures of all components were less than 10%. Therefore, the kinetics model may be an accurate descriptor of intrinsic kinetics of CO2 hydrogenation to DME. (c) 2015 American Institute of Chemical Engineers AIChE J, 61: 1613-1627, 2015