Introduction Ethanol is an alternative fuel that can be formed from natural gas and biomass-derived syngas via catalytic conversion. Cobalt-and copper-based bimetallic catalysts have been proposed for ethanol and higher alcohols synthesis as a substitute of high-cost noble metal catalyst1,2. In cobalt-copper based catalysts, cobalt and copper site pairs with close proximity are capable of dissociating CO and linearly adsorbing CO, forming the C-C bond and creating intermediates that form ethanol and higher oxygenates3. La2O3 is a promoter that can increase the dispersion of cobalt and promote cobalt-copper interaction4. Meanwhile, moderate basicity of lanthanum promoted catalysts can suppress methanation activity. Materials and Methods The purpose of this work is to study the promoting effect of La2O3 on cobalt-copper catalysts for synthesizing ethanol and higher alcohols from syngas. Different ratios of cobalt and copper are supported on lanthanum oxide by coprecipitation. BET measurements are done to ensure that there are no major textural differences among the catalysts. TPR-H2 studies the reduction behavior of the catalysts. DRIFTS under reaction conditions on these catalysts studies CO adsorption on the surface species and reaction mechanism. CO hydrogenation shows catalyst activity and selectivity in CO hydrogenation. Results and Discussion Results showed that lanthanum oxide promoters has great effects on selectivity. From TPR-H2 results, La2O3 increases cluster dispersion and promotes cobalt reduction. All the catalysts precursors in the study have very low crystallinity of CuO and Co3O4. DRIFTS study show that cobalt carbide is formed in the presence of syngas flow on the Cu1Co1La20, which is a new type of sites that can adsorb CO associatively and insert into CHx surface species that form higher alcohols5-7. CO hydrogenation test is performed at 30 bar, 270 °C and 2:1 H2 to CO ratio. Comparing with a reference catalyst promoted with alumina, lanthanum promoted catalyst displays lower activity, but higher selectivity to ethanol and higher alcohols. Methanation is inhibited on lanthanum promoted catalysts. During the reaction, cobalt carbide is slowly formed on lanthanum promoted catalysts, which leads to increasing selectivity to alcohols and decreasing selectivity to methane and C2+ hydrocarbon. Further CO hydrogenation tests on different cobalt copper ratio optimizes the composition to yield highest selectivity to ethanol

Role of lanthanum oxide on cobalt-copper catalyst for the conversion of syngas to ethanol

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.