脱氢
丙烷
氧化钒
色散(光学)
钒
退火(玻璃)
材料科学
化学工程
无定形固体
尖晶石
氧化物
化学
催化作用
结晶学
有机化学
复合材料
冶金
工程类
物理
光学
作者
Yu-Ling Shan,Huai-Lu Sun,Shilei Zhao,Kaixin Li,Kong-Hao Xia,Junwei Ding,Wenlong Yu
标识
DOI:10.1016/j.cej.2022.137969
摘要
Vanadium oxide-based catalysts are promising candidates for propane direct dehydrogenation. A strategy was developed in the present study to enhance the intrinsic activity and coking-resistance of supported VOx catalysts at the same time. The annealing temperature and VOx surface density were identified as regulation parameters to tailor the dispersion of VOx and micro-environment of V-O-Al active sites. The surface acidic VOx was found capable of inducing local structure rearrangement of transition alumina and the transformation of amorphous δ- to more crystalline θ-alumina at relatively lower temperatures, contributing to lowering VOx-support interactions and enhancing VOx reducibility. The DFT calculations verify that the chemical states of V-O active sites could be tuned by the ligand Al3+ coordination micro-environment, and the octahedral Al3+ serving as ligands contributes to enhancing the reducibility and C–H bond rupture capability of V-O site. The annealing temperature was also found capable of dispersing VOx species over alumina surface with the optimal temperature dependent of specific VOx loadings. As a consequence, the intrinsic activity of 3.1 V/Al2O3-900 and the deactivation rate of 3.1 V/Al2O3-700 with dominantly isolated VOx is 1.4 times and 0.65 times that of 3.1 V/Al2O3-550, respectively.
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