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

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 H-2 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 g(cat)(-1) h(-1) at 200 degrees C over the Co3O4-m catalyst, which was reduced at 300 degrees C. In addition, the selectivity for CH4 further decreased at 200 degrees 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 g(cat)(-1) h(-1)) was slightly lower than that of Co3O4-m catalysts under the same reaction conditions. (C) 2018 Elsevier Inc. All rights reserved.