N2O is an extremely potent greenhouse gas with a lifetime of 150 years. Consequently it is important to decompose N2O before it is released into the atmosphere. The aim of this study is to decompose N2O into N2 and O2 at temperatures ≤ 350 °C. In the current work, we have investigated the effects of repeated testing or repeated thermal pre-treatment on the activity of 2 wt.% Pd-Al2O3 catalyst. As the dissociation of N2O releases oxygen which can effectively poison a metallic catalyst surface, we have also evaluated the effect of adding a hydrocarbon to the gas stream.

Te-promoted (1%) vanadium phosphate catalyst (VPDTe) was prepared via VOPO4·2H2O by calcining its precursor VOHPO4·0.5H2O in a flow of n-butane/air. VPDTe catalyst has resulted a higher existence of V5+ phase with V5+/V4+ ratio of 0.23. SEM micrographs show that Te addition altered the arrangement of the platelets from "rose-like" clusters to layer with irregular shape. Te addition has also markedly lowered the reduction activation energies of the vanadium phosphate catalyst as revealed by TPR profile. The amount of active oxygen species associated with V4+ phase of the Te promoted catalyst was significantly higher than those of the unpromoted catalyst. These observations suggest that high mobility and availability of reactive oxygen species contributed to the enhancement of n-butane conversion up to 80% at 673 K, while only 47% over unpromoted catalyst (2400 h−1, 1.7% n-butane in air).

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

The reaction of VOPO4 center dot 2H(2)O, beta-VOPO4 and VOHPO4 center dot 0.5H(2)O with alcohols in an autoclave at elevated temperatures (100-400 degrees C) and pressures (1-150 bar) is described and discussed. The reduction of VOPO4? 2H2O with alcohols at ambient pressure is a standard method of preparation for VOHPO4 center dot 0.5H(2)O which is a valuable commercial catalyst precursor for the oxidation of butane to maleic anhydride. Surprisingly, the use of higher reaction pressures presents an unexplored region, and we show that primary alcohols at high temperature and pressure reduce both VOPO4 center dot 2H(2)O and beta-VOPO4 to tetragonal VPO4 center dot H2O, whereas VOHPO4 center dot 0.5H(2)O is reduced to form monoclinic VPO4 center dot H2O. Previously these materials have been prepared by slow hydrothermal synthesis requiring the presence of templates, and hence we present new more facile synthetic pathways to these V(III) compounds. The catalytic performance for the selective oxidation of butane to maleic anhydride of these materials pretreated in situ with butane/air is also described and discussed in terms of the structures of the materials formed under the reaction conditions.