Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane. Quarterly report, July - September 1996

This document covers the period July-September, 1996. Activities included studies of the oxidation of dimethyl ether over vanadyl pyrophosphate and synthesis of all previously acquired kinetic data. This synthesis revealed the need for additional data on methane and methanol oxidation and these experiments were performed. A further series of methanol oxidation/dehydration experiments was conducted on samples with varying surface acidity that have been described in earlier reports. Oxidation of methane over Cr- promoted VPO was also reinvestigated. The kinetic studies performed to date allow us to determine optimum conditions for methanol and formaldehyde production from methane using VPO catalysts, and in particular determine the effect of lean conditions (excess oxygen), oxygen deficient conditions (used in most other methane oxidation studies), and the potential of using the catalyst as a stoichiometric oxidant or oxygen carrier. However, unpromoted VPO yields only CO as the primary oxidation product. Studies of promoters have shown improvements in the formaldehyde selectivity but no methanol has been observed. The best promoters tested have been Fe and Cr (results for Cr are described in this report). We have also examined the use of iron phosphate for the methane conversion reaction. FePO{sub 4}is a more selectivity catalyst than the promoted VPO materials. Support of this iron phosphate on silica results in further improvements in selectivity. Current work is directed at understanding the improved selectivity for promoted VPO and at obtaining a knowledge of the optimum conditions for methane conversion of iron phosphate. 15 refs., 2 figs., 1 tab.