Ge adjusted microregion electron structures of lattice distortion in Cu/nGe-CeOx to boost CO2 hydrogenation to CH3OH
Developing high-performance supported non-precious metal copper-base catalysts for CO 2 hydrogenation is of extreme significance for the successful production of green methanol (CH 3 OH). Herein, Cu/ n Ge-CeO x catalysts ( n = 0, 0.25, 0.5, and 1 wt%) were synthesized via the incipient wetness impregnation method and comprehensively investigated using experiments and DFT calculations. Among all the catalysts, the Cu/0.5Ge-CeO x catalyst exhibited the highest concentration of oxygen vacancies, the smallest Cu grain size, and the most favorable regions for CO 2 adsorption. Compared to the Cu/0Ge-CeO x catalyst, the CH 3 OH yield was significantly improved over the Cu/0.5Ge-CeO x catalyst in the temperature range of 220–260°C under 3 MPa and a gas hourly space velocity of 3000 mL·g cat −1 ·h −1 . Especially at 260°C, the yield sharply increased from 35.23% to 82.21%, and this catalyst maintained high activity for 100 h. This was because the inert pair effect of the introduced Ge promoters induced lattice distortion on the support surface and regulated its microregion electron structures, while simultaneously establishing a highly active interface on the adjacent Cu cluster. This not only enabled an integrated process of in situ activated CO 2 and hydrogenation, but also inhibited the HCOO pathway, lowered the barrier of the rate-controlling step of the RWGS pathway, and reconciled some of its competing branching routes.
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