Abstract
A series of zirconium phosphate supported WOx solid acid catalysts with W loadings from 1-25 wt% have been prepared on high surface area zirconium phosphate by a surface grafting method. Catalysts were characterized by N-2 adsorption, FTIR, Raman, UV-Vis, P-31 MAS NMR, pyridine TPD and X-ray methods. Spectroscopic measurements suggest a Keggin-type structure forms on the surface of zirconium phosphate as a (equivalent to ZrOH2+)( ZrPW11O405-) species. All catalysts show high activity in palmitic acid esterification with methanol. These materials can be readily separated from the reaction system for re-use, and are resistant to leaching of the active heteropolyacid, suggesting potential industrial applications in biodiesel synthesis.