Effects of mesoporous structure and Pt promoter on the activity of Co-based catalysts in low-temperature CO2 hydrogenation for higher alcohol synthesis

Abstract

Mesoporous Co3O4 (Co3O4-m) was synthesized with mesoporous silica (KIT-6) as a hard template. Co3O4-m was characterized by in situ reduction XRD, BET, TEM, and H2 TPR. The partly reduced Co3O4-m was studied as a catalyst for higher alcohol synthesis from CO2 hydrogenation. The metallic Co reduced from Co3O4 was the main activity site for the CO2 hydrogenation. The ordered mesoporous structure of the Co3O4-m catalyst promotes the growth of carbon chains for the production of higher hydrocarbons and alcohols and reduces the selectivity for CH4 from that of the partially reduced Co3O4 nanoparticles. The highest yield of higher alcohols was obtained in 1.6 mmol gcat−1 h−1 at 200 °C over the Co3O4-m catalyst, which was reduced at 300 °C. In addition, the selectivity for CH4 further decreased at 200 °C over the Pt/Co3O4-m catalyst, while the selectivity for CO and alcohols increased, owing to the reverse water gas shift ability of Pt. However, the conversion of CO2 significantly decreased. The yield of higher alcohols (1.5 mmol gcat−1 h−1) was slightly lower than that of Co3O4-m catalysts under the same reaction conditions.