Partial oxidation of n-pentane over vanadium phosphorus oxide supported on hydroxyapatites

Abstract

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 cobalthydroxyapatite (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 temperatureprogrammed reduction (TPR). VPO is present in two phases, viz. (VO) 2 P 2 O 7 and VOPO 4 . With increase in the VPO loading on the hydroxyapatites, the (VO) 2 P 2 O 7 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. KEYWORDSSelective oxidation, n-pentane, vanadium phosphorus oxide, hydroxyapatite, maleic anhydride, phthalic anhydride.

Gas–Solid Oxidation of Unwashed Lignin to Carboxylic Acids

“…Scheme shows two alternative routes to depolymerize the substrate ( 1 ) catalytically: arrow A, a selective aerobic oxidation pathway in the presence of free oxygen (O 2 ); and arrow B, an anaerobic oxidative cleavage in its absence, with weakly bound oxygen. ,, Vanadium-based complexes, namely, VPP and HZSM-5-supported VPP catalysts, have catalyzed substrate ( 1 ) conversion. The VPP is a well-known selective and efficient catalyst to activate molecular oxygen, and oxidize it, even at room temperature. − ,− …”

Estudo de hidroxiapatita contendo própolis de origem brasileira: caracterização, atividade antimicrobiana e efeito citotóxico dos materiais

“…As análises de FTIR foram realizadas com o objetivo de identificar os grupos funcionais específicos tanto para os extratos secos de própolis verde e vermelha como para as amostras (HA-ETOH80, HA-GP20, HA-GP8, HA-RP20 e HA-RP8). Para os extratos secos de própolis verde e vermelha, os espectros de FTIR foram obtidos com objetivo principal de identificar grupos funcionais característicos de fenólicos e flavonoides totais, principais responsáveis pela atividade antimicrobiana destes extratos, uma vez que a composição da própolis é bastante complexa e variável, apresentando mais de 300 substâncias (SFORCIN, 2016 adsorvido da atmosfera durante o processo de síntese, uma vez que o procedimento é realizado em sistema aberto (GUERRA-LOPEZ et al, 2015;HE;DONG;DENG, 2016;JAFARI et al, 2016;ROGINA et al, 2016;SINGH, 2016;ZHANG et al, 2016). A Tabela 8 mostra os sinais obtidos para cada banda de absorção para a amostra HA-ETOH80 e suas respectivas atribuições.…”