Hydrothermally synthesized poorly-crystalline binary oxides with ZrW 2 O 8 composition: preparation, structural analysis, and catalytic activity for the alkylation of anisole with benzyl alcohol.

Hydrothermally synthesized poorly-crystalline metastable Zr-W binary hydroxide (W/Zr = 2), after calcination, was confirmed to be a strong solid acid catalyst to promote the alkylation of anisole with benzyl alcohol. The preparation conditions, structure of the as-prepared catalysts and the calcined hydroxides were investigated using XRD, nitrogen adsorption isotherms, TG-DTA, and XANES/EXAFS techniques. The crystalline phase was controlled by the hydrochloric acid concentration used for preparing a mother gel, and 5-9 M HCl was suitable for preparing the active phase. The tungsten species exists as a six-valent WO 6 distorted octahedron connected with the ZrO 7 unit via corner-sharing linkages. The incompleteness of the network structure is suggested to be responsible for the solid acidity.