The role of lattice oxygen species in the catalytic oxidation of n-butane to maleic anhydride has been investigated using β-VOP04 labeled with 180. The catalyst was prepared by stoichiometric reaction of (VO)2P207 with 1802 using solid state preparation techniques. The β-VOPO 7 218O 1 2 was characterized using laser Raman and Fourier transform infrared spectroscopies: preferential incorporation at P-O-V sites was observed. A pulse reactor was used to react n-butane, 1-butane, 1,3-butadiene, furan, γ-butyrolactone, and maleic anhydride with the catalyst in the absence of gas-phase O2. Incorporation of 18O into the products was monitored by mass spectrometry. Specific lattice oxygen sites could be associated with the reaction pathways for selective or nonselective oxidation. The results of this study also indicate that the initial interaction of n-butane with β-VOPO4 is fundamentally different from the initial interaction of olefins or oxygenated species. The approach used in this research-referred to as Isotopic Reactive-Site Mapping-is a potentially powerful method for probing the reactive lattice sites of other selective oxidation catalysts.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry