South African Journal of Chemistry
versão On-line ISSN 1996-840X
SINGH, Sooboo. Partial oxidation of n-pentane over vanadium phosphorus oxide supported on hydroxyapatites. S.Afr.j.chem. (Online) [online]. 2016, vol.69, pp. 1-8. ISSN 1996-840X. http://dx.doi.org/10.17159/0379-4350/2015/v69a1.
The selective oxidation of M-pentane to value-added products, maleic anhydride or phthallic anhydride by vanadium phosphorus oxide loaded on hydroxyapatites as catalysts and oxygen as oxidant was investigated. Hydroxyapatite (HAp) and cobalt-hydroxyapatite (Co-HAp) were prepared by the co-precipitation method and VPO with varying weight percentages (2.5-15.0 %) were loaded on the hydroxyapatite supports by the wet impregnation technique. The catalyst materials were characterized by surface area measurements, elemental analysis, powder X-ray diffraction (XRD), infrared spectroscopy (IR) and temperature-programmed reduction (TPR). VPO is present in two phases, viz.( VO)2P2O7 and VOPO4. With increase in the VPO loading on the hydroxyapatites, the (VO)2P2O7 phase also increased. From catalytic results, a conversion of 75 % of n-pentane and selectivity towards maleic anhydride, about 50 % and phthalic anhydride, about 25 %, were consistently achieved with loadings of 5.0 and 7.5 wt. % VPO at 360 °C for GHSVs of 1900 and 2300 h-1. Under optimum conditions, product yields of up to 40 % maleic anhydride and 20 % phthalic anhydride were obtained. It is proposed that the products formed through the diene intermediate.
Palavras-chave : Selective oxidation; M-pentane; vanadium phosphorus oxide; hydroxyapatite; maleic anhydride; phthalic anhydride.