Acetalization of glycerol with acetone to bio fuel additives over supported molybdenum phosphate catalysts

Abstract

The acetalization of glycerol with acetone was carried out over a series of molybdenum phosphate catalysts supported on SBA-15 with varying MoPO loadings ranging from 5-50wt%. These catalysts were characterized by X-ray diffraction, FT-IR, Laser Raman Spectroscopy, Ultraviolet–visible diffuse reflectance spectroscopy (UV DRS), NH3-TPD analysis, ex-situ pyridine adsorbed FT-IR analysis and pore size distribution measurements. The XRD results of unsupported MoPO show the formation of (MoO2)2P2O7 phase and this phase is present in a well dispersed state on the SBA-15. Raman spectra reveal the presence of MoPO species in the form of (MoO2)2P2O7 phase in the samples above 40wt% MoPO/SBA-15. The presence of both isolated tetrahedrally and isolated octahedrally coordinated Mo centers in the unsupported and supported MoPO are confirmed by the UVDRS findings. Ammonia TPD analysis suggests that the total acidity increased with MoPO loading and acidity of the catalysts was proved to be detrimental to assess the catalytic performance. The conversion and selectivity during the acetalization depends strongly on the reaction time, catalyst loading and glycerol to acetone molar ratio. Acetalization of glycerol suggests that 40wt% MoPO/SBA-15 sample exhibited better catalytic properties than other catalysts investigated. The catalytic properties are well correlated with the acidic functionalities of the catalysts.