Direct synthesis of CH3OH from CO2 hydrogenation over Ni5Ga3/SiO2 catalysts

[Display omitted] •Ni5Ga3/SiO2 catalysts were prepared by a co-precipitation method;•Effects of reactions on intrinsic properties of catalysts were investigated;•A fixed–bed column for the one-step CO2 conversion was applied;•High–value CH3OH products were obtained from a direct CO2 hydrogenation;•Payback of a 10–TPD plant of CO2 converted to methanol are 1.86 years. Ni5Ga3/SiO2 catalysts were synthesized by co-precipitation method. The catalytic components of Ni5Ga3/SiO2 were gallium species, which was confirmed by X–ray photoelectron spectroscopy (XPS) measurements. Notably, the fine structures of the metal atoms in Ni5Ga3/SiO2 were obtained using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The optimal catalytic performances of Ni5Ga3/SiO2 (CO2 conversion = 100.0 %, CH3OH selectivity = 84.7 %, CH3OH yield = 84.7 %) were obtained at 250 °C. At 250 °C, the low activation energies and Gibbs energies of formation for CH3OH (Ea = 42.604 kJ mol−1, hG523E= 3.26 kJ mol−1) revealed that their spontaneities were significantly enhanced by catalysts. Cost assessment of a 10-TPD (ton per day) waste gas utility process for a petrochemical refinery plant shown that the overall income was USD$88,932/d with a payback of 1.86 years. This work provides a serial route to produce high-value-added chemicals in large scale from industrial emitted CO2 and syngas utility.