Synthesis and catalytic properties of porous Nb–Mo oxide solid acid

Several porous NbxMo10−x mixed oxides prepared from NbCl5 and MoCl5 in the presence of block copolymer surfactant Pluronic P-123 were examined as potential solid acid catalysts. Amorphous mesoporous structures were observed in samples with x from 10 to 9, whereas samples with higher Mo concentrations (x = 3–8) formed large pores by inter-particle voids and a non-porous structures with crystallized molybdenum oxide (MoO3) were observed in samples with x from 0 to 2. The acid strength increased with increasing the Mo content in NbxMo10−x oxides, which was determined by NH3 temperature-programmed desorption (NH3-TPD) and Fourier transform infrared (FT-IR) spectroscopy using pyridine as a probe molecule. Porous Nb3Mo7 oxide exhibited the highest acid-catalytic activity for the Friedel–Crafts alkylation of anisole due not only to mole ratio of Nb/Mo but also to pore structure.