(763b) Understanding Active Sites in Ethanol Synthesis on PtCo Catalysts Prepared Using Atomic Layer Deposition

Production of ethanol and other C₂₊ oxygenates from syngas has brought continued interest over the past decades due to their importance as alternative transportation fuels and industrial feedstocks. Currently, no catalyst meets the selectivity and activity requirements for industrial-scale production of ethanol. In this work, we synthesize transition metal catalysts using atomic layer deposition (ALD) to study this reaction. Using ALD, we can introduce metalorganic precursors in the gas phase and deposit catalytic materials on surfaces layer-by-layer. Through controlled deposition of metal layers, we create model alloy catalysts to gain insights into the mechanism of syngas conversions to ethanol and other oxygenates. In particular, platinum cobalt alloys have been reported as a potential catalyst candidate. We create PtCo catalysts using ALD and compare their catalytic performance and structure to catalysts prepared using traditional methodologies. The addition of Pt using ALD to Co catalysts results in increased selectivity towards methanol and higher alcohols and decreased selectivity towards longer chain hydrocarbon products. Using in situ diffuse reflectance infrared Fourier transform spectroscopy, we demonstrate that the interplay of bridging and linear CO species is important in carrying out oxygenate synthesis on PtCo catalysts.