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Designing oxidation catalysts

Hutchings, Graham John and Taylor, Stuart Hamilton 1999. Designing oxidation catalysts. Catalysis Today 49 (1-3) , pp. 105-113.

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Abstract

A simplified approach is described for the design of oxidation catalysts. It is based on three components and for selective oxidation the approach involves identifying catalysts that (a) do not catalyse the oxidation of the required product under the reaction conditions to be tested, (b) activate the oxidant and (c) activate the substrate. This approach is initially demonstrated to identify components of novel methane oxidation catalysts for the formation of methanol. The approach seeks to identify oxides that are capable of activating methane and oxygen, but do not destroy methanol, the desired product. From the perspective of methanol stability the oxides MoO3, Nb2O5, Ta2O5 and WO3 all produced high methanol conversion, however, high selectivities towards formaldehyde and dimethylether were obtained, with only low levels of carbon oxides throughout the range of conversions. The products formaldehyde and dimethylether were desirable by-products from a methane partial oxidation process, hence these oxides are considered to be suitable catalyst components. The activation of oxygen was probed using the 16O2/18O2 exchange reaction. The activation of methane has been probed by the exchange reaction with deuterium under non-oxidative conditions. The most active catalyst was Ga2O3 which exhibited normalised exchange rates several orders of magnitude greater than the other catalysts. On the basis of these results we tested a simple two component oxide catalyst for methane partial oxidation based on a Ga2O3/MoO3 physical mixture, which showed an increased methanol yield compared with the homogeneous gas phase reaction in the reactor tube packed with quartz chips. The increased methanol yield has been attributed to the development of a co-operative effect between the Ga2O3 and MoO3 oxide phases. The design approach has also been extended to the design of total oxidation of hydrocarbons for VOC destruction using benzene as a model VOC. In this case the design approach seeks to identify catalysts that can activate the substrate and the oxidant and also destroy the possible partial oxidation products. This approach is used to demonstrate that uranium oxide catalysts are extremely active for the oxidation destruction of hydrocarbons and chlorohydrocarbons. The degree of success from this approach indicates the validity of this novel approach in both the identification of selective and total oxidation catalysts. © 1999 Elsevier Science B.V. All rights reserved.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Cardiff Catalysis Institute (CCI)
Subjects: Q Science > QD Chemistry
Uncontrolled Keywords: Catalysts; Methanol; Oxidation; VOC destruction
Additional Information: cited by (since 1996) 31
Publisher: Elsevier BV
ISSN: 09205861
Last Modified: 04 Jun 2017 02:10
URI: http://orca-mwe.cf.ac.uk/id/eprint/10307

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