焙烧气氛对丙烷氨氧化Mo-V-Te-Nb-O催化剂性能的影响

Effects of Calcination Atmosphere on Catalytic Performance of Mo-V-Te-Nb-O for Propane Ammoxidation

采用不同气氛焙烧共沉淀方法制备MoV0.31Te0.23Nb0.24氧化物催化剂,考察焙烧气氛对该催化剂结构及其催化丙烷氨氧化反应性能的影响,并采用X-射线粉末衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)等手段对所制备的催化剂进行表征。结果表明:采用惰性的氮气气氛焙烧的MoV0.31Te0.23Nb0.24氧化物催化剂具有良好的丙烷氨氧化反应性能。在氮气气氛下焙烧的催化剂,构成催化剂的各种元素在焙烧过程中形成了价态分布合理的活性相M1和M2,用于催化丙烷氨氧化反应,丙烷转化率可达58.7%,丙烯腈收率为35.0%;在空气和氧气气氛下焙烧的催化剂,其组成中各元素以高价态的单一氧化物形式存在,不利于丙烷选择性氧化生成丙烯腈。

MoVo0.31Te0.23Nb0.24 oxide catalysts for propane ammoxidation were synthesized by co-precipitation method under different calcination atmosphere conditions. The effects of calcination atmosphere on the physicochemical properties of the catalysts were investigated. The catalysts were characterized by X-ray diffraction （XRD）, Raman Spectrum and X-ray photoelectron spectroscopy （XPS）. The catalytic performance was evaluated using propane ammoxidation to acrylonitrile as a model reaction. The results showed that the obtained catalyst exhibits good performance on propane ammoxidation under an inert atmosphere of nitrogen in the calcination process. This was because, under the nitrogen atmosphere, the elements constituting the catalyst formed an appropriate distribution of the active phases of M1 and M2 in a reasonable valence state during the calcination process. That significantly enhanced the catalytic performance for propane ammoxidation： propane conversion was up to 58.7%, and acrylonitrile selectivity was up to 35.0%. Under air and oxygen atmosphere during the calcination, simple oxides were formed in a higher valence state, which was not in favor of the selective oxidation of propane to acrylonitrile.