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 VOPO4dot operator2H2O were conducted in 2-butanol alone and in a mixed-alcohol solvent (2-butanol and ethanol). Whereas both processes produced crystallites of pure VOHPO4dot operator0.5H2O, much smaller and thinner crystallites (average size, 340 x 35 nm) were formed in the mixed alcohol compared with 2-butanol alone (average size 950 x 200 nm). The small, thin crystallites of precursor VOHPO4dot operator0.5H2O 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. [PUBLICATION ABSTRACT]