Studies on a niobia-supported VPO catalyst for glycerol dehydration

Abstract

Niobia supported VPO catalysts were synthesized using the deposition–precipitation method with VPO loadings increasing from 5 to 50 weight percent. The catalysts are characterized by various adsorption studies like BET surface area, TPR, TPD and spectroscopic studies like XRD, UV-DRS, FT-IR, and X-ray photoelectron spectroscopy. The dehydration of glycerol in the vapour phase was assessed in terms of its catalytic characteristics. The XRD analysis result of pure VPO validates the development of the vanadyl pyrophosphate phase. Despite higher VPO loadings, the supported VPO (VPO/Nb) study results indicate that the VPO species is widely distributed over the support. The results of the FTIR investigation indicate that with increasing VPO loadings, the phase of vanadyl pyrophosphate develops on niobia. According to the UV-DRS investigation, there may be some vanadium orthophosphate phase formation in addition to vanadyl pyrophosphate phase formation. XPS analysis findings confirmed the formation of V⁴⁺ species (VPP phase) over the support, and the binding energy values of V⁴⁺ were found to be unaltered with the successive addition of VPO loadings. The TPR experiments revealed that the reducible temperature of bare VPO is significantly greater than that of the niobia-assisted VPO catalyst. The ammonia TPD analysis findings show that the supported VPO has a higher total acidity value than either pure VPO or niobia. The catalytic performance of the samples was found to have relied on the total acidity of the catalyst.