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,

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Nanoporous phospho-tungstate organic-inorganic hybrid materials have been synthesized from sodium tungstate and mono-n-dodecyl phosphate (MDP), which was used as both surfactant and phosphorus precursor. These hybrid materials were thoroughly characterized by N 2 adsorption, elemental analysis, powder XRD, FTIR, Raman, TG, TEM and XPS and possess lamellar structures with interlayer spacings of 3.2 nm. A plausible method for formation of hybrid materials comprised of lacunary Keggin anions and micelles of surfactants is proposed.

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