Effect of Crystalline Phases for VPO Catalysts on the Oxidation of Butane: Thermodynamics and Kinetics
Xia Zhang, Haibo Wang, Lianke Gou, Lanpeng Li, Aijun Duan, Zhengkai Cao
Abstract
Serial VPO catalysts with different compositions of crystalline phases were prepared at various activation temperatures. The characterization results revealed that the proportion of V5+ species, the acidity levels, and the surface P/V ratios of VPO catalysts showed an increasing tendency with activation temperature. The performances of n-butane oxidation for serial VPO catalysts were tested at different conditions. It was shown that the S-405 catalyst (activated at 405 °C) presented the highest conversion of n-butane (75.2%) at a GHSV of 1000 h–1 and the highest selectivity for maleic anhydride (MA) (68.9%) at a GHSV of 1800 h–1, which were attributed to S-405’s high intensities at different crystalline faces, the highest amount of acidity (5.52 mL/g), the highest number of total removed oxygen atoms (2.88 × 1021 atom g–1), and the best reducibility. In addition, the kinetic and thermodynamic analyses confirmed that the S-405 catalyst possessed the best activity and selectivity of n-butane oxidation, and the effects of Lat-O and Sur-O on the selectivity for MA were also disclosed.