title: Controlling activity and selectivity using water in the Au-catalysed preferential oxidation of CO in H2.
abstract: Industrial hydrogen production through methane steam reforming exceeds 50 million tons annually and accounts for 2-5% of global energy consumption. The hydrogen product, even after processing by the water-gas shift, still typically contains ∼1% CO, which must be removed for many applications. Methanation (CO + 3H2 → CH4 + H2O) is an effective solution to this problem, but consumes 5-15% of the generated hydrogen. The preferential oxidation (PROX) of CO with O2 in hydrogen represents a more-efficient solution. Supported gold nanoparticles, with their high CO-oxidation activity and notoriously low hydrogenation activity, have long been examined as PROX catalysts, but have shown disappointingly low activity and selectivity. Here we show that, under the proper conditions, a commercial Au/Al2O3 catalyst can remove CO to below 10 ppm and still maintain an O2-to-CO2 selectivity of 80-90%. The key to maximizing the catalyst activity and selectivity is to carefully control the feed-flow rate and maintain one to two monolayers of water (a key CO-oxidation co-catalyst) on the catalyst surface.
authors.affiliation: Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, USA.|Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors.forename: Johnny
authors.initials: J
authors.lastname: Saavedra
authors.affiliation: Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, USA.
authors.forename: Todd
authors.initials: T
authors.lastname: Whittaker
authors.affiliation: Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802-4400, USA.
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Pursell
authors.affiliation: Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802-4400, USA.|Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802-4400, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Rioux
authors.affiliation: Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, USA.
authors.forename: Bert D
authors.initials: BD
authors.lastname: Chandler