A series of zirconium phosphate supported WO x 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, 31 P MAS NMR, pyridine TPD and X-ray methods. Spectroscopic measurements suggest a Keggin-type structure forms on the surface of zirconium phosphate as a (MZrOH 2 + )(ZrPW 11 O 40 52 ) 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.
Experimental Catalyst preparationPorous zirconium phosphate. A simple hydrothermal synthesis procedure was used 24 during which 0.01 mol of zirconium n-propoxide, (70 wt% solution in 1-propanol, Aldrich) was added drop wise to a 60 mL solution of H 3 PO 4 (0.1 mol L 21 ) under stirring. After a further 2 h stirring at room temperature,
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.