The Oxidation of Methane at Low Temperatures Over Zirconia-Supported Pd, Ir and Pt Catalysts and Deactivation by Sulfur
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The Oxidation of Methane at Low Temperatures Over Zirconia-Supported Pd, Ir and Pt Catalysts and Deactivation by Sulfur Poisoning Hirofumi Ohtsuka
Received: 23 August 2010 / Accepted: 15 November 2010 / Published online: 30 November 2010 Ó Springer Science+Business Media, LLC 2010
Abstract The oxidation of methane over zirconiasupported Pd, Ir, and Pt catalysts at low temperatures under an oxidizing atmosphere and the effect of SO2 on this reaction were investigated. An Ir–Pt/ZrO2 catalyst exhibited high activity and low deactivation by SO2. Characterization of the catalyst indicated the presence of a highly oxidized Pt species that was stabilized by the addition of Ir. Keywords Platinum Iridium Methane Catalytic oxidation X-ray absorption fine structure
1 Introduction Among hydrocarbons, methane produces the least amount of carbon dioxide per heat of combustion unit. In comparison to other fossil fuels, the combustion of natural gas (methane) results in lower emissions of greenhouse gases and, consequently, the use of methane is increasing on a global level. However, methane itself is also a greenhouse gas with a global warming effect that is 25 times greater than carbon dioxide [1]. Methane is emitted from various sources such as agricultural activities, waste treatment, industrial processes, fuel combustion, and coal mining. Air that is ventilated from coal shafts contains methane in low
Electronic supplementary material The online version of this article (doi:10.1007/s10562-010-0506-x) contains supplementary material, which is available to authorized users. H. Ohtsuka (&) Energy Technology Laboratories, Osaka Gas Co., Ltd, 6-19-9 Torishima, Konohana-ku, Osaka 554-0051, Japan e-mail: [email protected]
concentrations (0.1–1 vol.%); this is called ventilation air methane (VAM). The global VAM emission is estimated to be equivalent to 230 Mt–CO2/y [2, 3]. Therefore, the reduction of VAM is needed to decrease global warming. Catalytic oxidation is effective for the abatement of diluted combustible gases and is widely used as a means for controlling volatile organic compounds (VOCs) released from industrial sources [4]. In order for catalytic oxidation to be an economically viable method of VAM abatement, a highly active catalyst is needed that can oxidize methane at low temperatures. The catalytic oxidation of methane has been widely studied for use in flameless combustion and for methane abatement from combustion exhaust [5–7]. Yao compared the oxidation of lower alkanes (C1–C4) over Pd, Pt, and Rh/ Al2O3 catalysts under oxidizing conditions and found that the activity for methane oxidation decreases in the following order: Pd [ Rh [ Pt, whereas Pt is superior for the oxidation of C3–C4 alkanes [8]. Oh and coworkers investigated methane oxidation over Al2O3-supported catalysts under oxidizing conditions and reported that the activity for methane oxidation decreases in the following order: Pd [ Rh [ Pt [9]. Burch and Loader compared the activities of Pt/Al2O3 and Pd/Al2O3 catalysts under oxidizing, s
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