Electrified synthesis of n-propanol using a dilute alloy catalyst

Abstract

N-propanol is an important industrial solvent but the current industrial routes for its production rely on fossil fuels and generate high carbon dioxide emissions. Replacing fossil processes with electrochemical systems powered using renewable energy offers one route to reduce the carbon intensity of n-propanol manufacture. The electrosynthesis of n-propanol via carbon monoxide electroreduction relies on the coupling of C1 and C2 intermediates, and these are preferentially stabilized on different sites. Here we pursued the synthesis of catalysts in which a high-oxygen-affinity metal (such as Sn in the best catalysts herein) is present in dilute quantities within a Cu matrix. The Sn–Cu catalyst is then formed into a catalyst/carbon/ionomer heterojunction architecture that reverses electro-osmotic drag to concentrate the n-propanol produced. We achieve n-propanol electrosynthesis from carbon monoxide with a Faradaic efficiency of 47 ± 3% and a concentration of 30 wt% at an energy efficiency of 24%. We report stable n-propanol electrosynthesis for 120 h in a membrane-electrode assembly electrolyser. Electrosynthesis of n-propanol from CO has been limited by poor selectivity and low product concentration. Here a Sn–Cu catalyst/carbon/ionomer heterojunction is prepared where the adjacent atomic active sites favour the coupling of C1 and C2 intermediates to C3 product with 47% Faradaic efficiency and the reversal of electro-osmotic drag concentrates the product to 30 wt%.