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

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An intrinsic kinetics model was established for CO2 hydrogenation to dimethyl ether (DME) with a Cu–Fe–Zr/HZSM‐5 catalyst based on H2/CO2 adsorption, simulation, and calculation of methanol synthesis from CO2 intermediates and experimental data. H2/CO2‐temperature programmed desorption results show a dissociative H2 adsorption on Cu site; CO2 was linearly adsorbed on Fe3O4 weak base sites of the catalyst; the adsorbing capacity of H2 and CO2 increased after Zr‐doping. Density functional theory analysis of methanol synthesis from CO2 and H2 revealed a formate pathway. Methanol synthesis was the rate‐limiting step (173.72 kJ·mol−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. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1613–1627, 2015