CATALYTIC ETHANOL STEAM REFORMING Am. Chem. Soc., Div. Pet. Chem. 2008, 51 p.1&2 M. Scott B.Sc. M.Sc.(hons) Department of Chemistry The University of Auckland Handbook of Green Chemistry, Wiley 2008 Topics in Catalysis, in press Science, in press

H 2 from ethanol Traditional Energy non-sustainable Renewable Efficient

Renewable energy cycle Photosynthesis 2807 kJ/mol C 6 H 12 O 6 Glucose H 2 combustion -286 kJ/mol Fermentation 15 kJ/mol Steam reforming 173 kJ/mol 6CO H 2 + O 2 + H 2 O 2CH 3 CH 2 OH + 2CO 2 Ethanol + hν 6CO H 2 O ∆

The catalyst Cerium dioxide nanoparticles as the supporting material. Rhodium metal dissociates sp 3 C-H bond Rh/CeO 2 dissociates C-C bond of ethanol Palladium excels in hydrogenation and oxidation Bimetallic Rh,Pd/CeO 2 displays ideal properties

Steam Reforming An activated process 298K; Ethanol on reduced Rh/CeO 2 J. Catal. 208, (2002) CO

Catalyst manufacture Precipitation Deposition CeO 2 nano-particles pH K

Catalytic testing 6:1 water to ethanol ratio shows higher CH 4 conversion than 3:1 ratio => higher H 2 vol. % Effects of varying reaction temperature Effects of varying weight percentage loading noble metal Varying throughput (2.5, 5, 6.5 and 11.5 mL/hour)

CH 3 CH 2 OH → CH 4 + CO + H 2 ΔH 0 = 50 kJ/mol CO + H 2 O → CO 2 + H 2 ΔH 0 = -41 kJ/mol CH 4 + 2H 2 O → CO 2 + 4H 2 ΔH 0 = 164 kJ/mol Temperature dependence

Temperature Programmed Desorption Water CH 3 CH 2 - Acetaldehyde CH 3 CH 4 CO CH 3 CH 2 - CeO 2 500K & 773K 1%Pd,1%Rh/CeO 2 375K & 525K CO 2

Effect of metal loading 11.5 mL/hour, 6:1 and 773K wt.% on ceria Vol.% H 2 Vol.% CO 2 Vol.% CH 4 Vol.% CO Χ% max. H 2 yield 1%Pd %Rh ½%Rh, ½%Pd ½%Rh, 1%Pd ½%Rh, 2%Pd

Transmission Electron Microscopy Pd,Rh alloy Used catalyst Alloying of Rh and Pd Reduction of Rh 2 O 3 Restructuring of Support Origins at interface Lowering CN of Cerium

Rh/CeO 2 based catalyst Bimetallic catalyst very active Low metal loadings show best activity Active sites at Rh-Ce and Pd-Ce interface High temperature required for CH 4 oxidation CH 4 reforming and CO oxidation inadequate Dramatic restructuring occurring Activation of catalyst occurring No signs of deactivation CH 3 CH 2 OH + 3H 2 O → 6H 2 + 2CO 2 ∆H=173 kJ/mol

Future research In situ FTIR TPD studies Further XPS studies Near Edge X-ray Absorption Fine Structure Further PAS and TEM Maximise outflow Doping ⅓wt.%Rh,⅓wt.%Pd,⅓wt.%Ni/Ce 0.75 Zr 0.25 O 2

Inverse Opal Ceria 20000x x Scanning Electron Microscopy Transmission Electron Chem. Mater. 2008, 20, 1183–1190 Microscopy 3D macroporous structure Resistant to sintering to 1073K Allow gas low through pores High surface to volume ratio

Acknowledgments: Associate Professor Hicham Idriss Supervisor Dr Geoffrey Waterhouse, Dr William Chiu, Dr Maria Goeffrey University of Auckland Graduates Alister Gardiner and Simon Arnold Industrial Research Limited, Christchurch Professor Jordi Llorca (HRTEM) Universitat Politècnica de Catalunya, Barcelona, Spain Dr Steven J. Pas (PAS) Commonwealth Scientific and Industrial Research Organisation (CSIRO) Manufacturing and Materials Technology, Victoria, Australia Mark Blackford (TEM) Australia’s Nuclear Science and Technology Organisation, Lucas Heights, Sydney, Australia

XPS 1%Rh,1%Pd/CeO 2 and PAS 1 Ethanol + 3 water at 773 K, 3 hours at ca. 100 Torr E B = hν – (φ + E K ) Voids in the bulk PAS 2%Rh,2%Pd/CeO 2 Oxidation of CeO 2 Reduction of metal Homogenization Growth of voids