title: Stable amorphous georgeite as a precursor to a high-activity catalyst.
abstract: Copper and zinc form an important group of hydroxycarbonate minerals that include zincian malachite, aurichalcite, rosasite and the exceptionally rare and unstable--and hence little known and largely ignored--georgeite. The first three of these minerals are widely used as catalyst precursors for the industrially important methanol-synthesis and low-temperature water-gas shift (LTS) reactions, with the choice of precursor phase strongly influencing the activity of the final catalyst. The preferred phase is usually zincian malachite. This is prepared by a co-precipitation method that involves the transient formation of georgeite; with few exceptions it uses sodium carbonate as the carbonate source, but this also introduces sodium ions--a potential catalyst poison. Here we show that supercritical antisolvent (SAS) precipitation using carbon dioxide (refs 13, 14), a process that exploits the high diffusion rates and solvation power of supercritical carbon dioxide to rapidly expand and supersaturate solutions, can be used to prepare copper/zinc hydroxycarbonate precursors with low sodium content. These include stable georgeite, which we find to be a precursor to highly active methanol-synthesis and superior LTS catalysts. Our findings highlight the value of advanced synthesis methods in accessing unusual mineral phases, and show that there is room for exploring improvements to established industrial catalysts.
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Simon A
authors.initials: SA
authors.lastname: Kondrat
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Smith
authors.affiliation: The UK Catalysis Hub, Research Complex at Harwell, Harwell, Oxon OX11 0FA, UK.|Kathleen Lonsdale Building, Department of Chemistry, University College London, Gordon Street, London WC1H 0AJ, UK.
authors.forename: Peter P
authors.initials: PP
authors.lastname: Wells
authors.affiliation: Diamond Light Source, Didcot OX11 0DE, UK.|Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Chater
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: James H
authors.initials: JH
authors.lastname: Carter
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Morgan
authors.affiliation: Center for Electron Nanoscopy, Technical University of Denmark, Fysikvej 307, DK-2800 Kgs Lyngby, Denmark.
authors.forename: Elisabetta M
authors.initials: EM
authors.lastname: Fiordaliso
authors.affiliation: Center for Electron Nanoscopy, Technical University of Denmark, Fysikvej 307, DK-2800 Kgs Lyngby, Denmark.
authors.forename: Jakob B
authors.initials: JB
authors.lastname: Wagner
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.|Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Davies
authors.affiliation: Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, Pennsylvania 18015, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Lu
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Bartley
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Stuart H
authors.initials: SH
authors.lastname: Taylor
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Spencer
authors.affiliation: Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, Pennsylvania 18015, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Kiely
authors.affiliation: Johnson Matthey, PO Box 1, Belasis Avenue, Cleveland TS23 1LB, UK.
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Kelly
authors.affiliation: Johnson Matthey, PO Box 1, Belasis Avenue, Cleveland TS23 1LB, UK.
authors.forename: Colin W
authors.initials: CW
authors.lastname: Park
authors.affiliation: Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Rosseinsky
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Hutchings