Characterization of supported Cu-Zn/graphene aerogel catalyst for direct CO2 hydrogenation to methanol: Effect of hydrothermal temperature on graphene aerogel synthesis

摘要

Reduced graphene oxide aerogel (rGOae) was synthesized via hydrothermal reduction and following freeze-drying method. The as-prepared material was then used as a novel support of Cu-Zn/rGOae catalyst for the direct CO2 hydrogenation to methanol. Moreover, in situ X-ray absorption near-edge structure (XANES) spectroscopy was applied to evaluate the oxidation state of the Cu and Zn species during the H-2 reduction process at 350 degrees C with a holding time of 90 min. The effects of the hydrothermal reduction temperature of rGOae support and Cu-Zn metal loading contents were investigated. Interestingly, the hydrothermal reduction at 140 degrees C provided the highest surface area (458 m(2) g(-1)), and 15wt%Cu-Zn/rGOae catalyst achieved the highest methanol production (94.53 mg(MeOH) g(cat)(-1) h(-1)) at a reaction temperature of 250 degrees C and pressure of 15 bar.