Cu/g-C3N4 modified ZnO/Al2O3 catalyst: methanol yield improvement of CO2 hydrogenation

Replacing ZnO with g-C3N4-ZnO hybrid in Cu/ZnO/Al2O3 catalysts for CO2 hydrogenation leads to enhanced methanol yield and selectivity, which shows a volcano-type relationship with g-C3N4 amount (0-15 wt% in g-C3N4-ZnO) in Cu/g-C3N4-ZnO/Al2O3 catalysts with the highest improvement at 5 wt% g-C3N4. The methanol space-time yield reaches 5.73 mmol h(-1) gcu(-1) (12 bar, 250 degrees C) for Cu/5 wt% g-C3N4-ZnO/Al2O3, superior to the highest methanol yield (5.45 mmol h(-1)gc(-1)) of industrial catalyst HiFUEL-R120 obtainable under the same pressure. Time-resolved photoluminescence, electronic spin resonance and temperature-programmed reduction characterizations support the promotion from enhanced strong metal-support interaction in modified catalysts caused by introduced electron-rich support.