Physico-chemicals and catalytic properties of manganese-promoted vanadium phosphate (VPO) catalyst

Abstract

The addition of 1% Mn promoter to vanadium phosphate catalyst led to doubling of the specific surface area from 20.3 (unpromoted) to 39.4 m 2 g -1 . The XRD pattern of the Mn-promoted catalyst gave only the characteristics of the (VO) 2 P 2 O 7 phase, indicating that the Mn was incorporated into the crystal lattice of the catalyst. The Mn-promoted catalyst was also twice as active in removing the total amount of oxygen. However, since the only oxygen species related to V 4+ being removed and no oxygen species associated with V 5+ was observed, the nbutane conversion was not much improved as compared to the unpromoted counterpart. A necessary amount and distribution of the V 5+ phase in a well crystalline V 4+ phase is essential in order to enhance the catalytic performance in the mild oxidation of n-butane to maleic anhydride.

Dependence of n-Butane Activation on Active Site of Vanadium Phosphate Catalysts

“…16 m 2 g -1 (for undoped), 14 m 2 g -1 for VPDBi1Fe1, 12 m 2 g -1 for VPDBi1Fe2 and 18 m 2 g -1 for VPDBi2Fe1. In our earlier studies, we had shown that the incorporation of 1% of Bi increased the surface area [3]; however, doping with 1% of Fe significantly lowered the surface area [6]. The higher concentration of Bi of doped catalyst (VPDBi2Fe1) in this study may encourage the formation of crystal phases with a slightly higher surface area and hence the slight variations in surface area we observe here are consistence with our earlier study.…”

“…catalyst are necessary [15][16][17] although an excess of this oxygen was observed to be detrimental. Our previous result on Bi-promoted VPD catalysts shows an enhancement of the activity [3] whereas Fe was found to reduce the conversion of the catalyst which was prepared via dihydrate route [6]. A mixture of Bi-Fe dopants in this case induced to a low activity of the catalyst due to two salient observations.…”

“…/V 4? ratio of *0.25 was suggested to give a high activity [6]. Secondly, the low amount of active oxygen species (O -) since V 4?…”

Vanadium Phosphate Materials as Selective Oxidation Catalysts

“…The promotional effects of cobalt (148,150,165,167,169,173,179,182,(191)(192)(193)(194)(195)(196)(197)(198)(199)(200)(201)(202)(203) and iron (66,148,166,167,171,176,(179)(180)(181)(193)(194)(195)201,(204)(205)(206)(207) have been widely investigated recently. Abdelouahab et al (193) considered the effects of these promoters on the structure of catalysts prepared with organic solvents.…”

Effect of Different Calcination Duration on Physicochemical Properties of Vanadium Phosphate Catalysts

“…Our group has been investigated the effect of the different calcinations duration of nbutane/air pretreatment on the vanadium phosphate catalysts synthesized via organic method 4,5 . In this paper, we would like to study the effect of different calcination duration on the vanadium phosphate catalysts prepared via VPO 6,7 and VPD 6,8,9 method . The precursors were calcined in an inert environment to produce catalysts which mainly consist of (VO) 2 P 2 O 7 phase.…”