Selective oxidation of n-butane over nanosized crystallites of (VO)2P2O7 synthesized by an exfoliation–reduction process of VOPO4⋅2H2O in a mixture of 2-butanol and ethanol

Intercalation, exfoliation, and reduction of VOPO4⋅2H2O were conducted in 2-butanol alone and in a mixed-alcohol solvent (2-butanol and ethanol). Whereas both processes produced crystallites of pure VOHPO4⋅0.5H2O, much smaller and thinner crystallites (average size, 340 × 35 nm) were formed in the mixed alcohol compared with 2-butanol alone (average size 950 × 200 nm). The small, thin crystallites of precursor VOHPO4⋅0.5H2O could be transformed into sharply angular nanosized crystallites (60 nm long and 31 nm thick) of highly crystalline (VO)2P2O7, without mesopores. When used as a catalyst, this compound exhibited higher activity and selectivity to maleic anhydride (75% at 80% conversion) for selective oxidation of n-butane compared with that derived from the precursor prepared in 2-butanol alone. The high activity of the nanosized crystallites of (VO)2P2O7 is attributed to their large surface area (40 m2 g−1), which is due to their smaller dimensions, and their high selectivity may be attributed to the lack of mesopores as well as their highly crystalline state.