Efficient dehydration of methyl lactate to acrylic acid using Ca3(PO4)2-SiO2 catalyst

A series of catalysts consisting of Ca-3(PO4)(2) supported on SiO2 (silicate, colloidal silica and fumed silica) and Ca-3(PO4)(2)-SiO2 (silicate) with different loadings of Ca-3(PO4)(2) (70 to 95 wt.%) was prepared by sol-gel and wet-impregnation methods. These catalysts were characterized by N-2 isotherm for specific surface area. XRD for crystallinity, TPD-NH3 for total acidity and TPR-CO2 for basicity and SEM for morphological features of the active phases over the support. All the catalysts were found to be active in the vapor phase dehydration of methyl lactate (ML) to give mainly acrylic acid (AA), methyl acrylate (MA). Among the catalysts, Ca-3(PO4)(2)-SiO2(silicate) of (80:20 wt.%) was found to be an efficient catalyst in the dehydration of ML, which gave 73.6% conversion of ML with selectivity for AA and MA together (77.1%). (C) 2010 Elsevier B.V. All rights reserved.