oa South African Journal of Chemistry - Partial oxidation of n-pentane over vanadium phosphorus oxide supported on hydroxyapatites : research article
|Article Title||Partial oxidation of n-pentane over vanadium phosphorus oxide supported on hydroxyapatites : research article|
|© Publisher:||South African Chemical Institute (SACI)|
|Journal||South African Journal of Chemistry|
|Affiliations||1 University of KwaZulu-Natal|
|Publication Date||Jan 2016|
|Pages||1 - 8|
|Keyword(s)||Hydroxyapatite, Maleic anhydride, n-pentane, Phthalic anhydride, Selective oxidation and Vanadium phosphorus oxide|
The selective oxidation of n-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.
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