丙烷氨氧化制丙烯腈改性Al-V-Sb-O_x催化剂的结构特征

Characterization of modified Al-Sb-V-O_x catalyst for propane ammoxidation to acrylonitrile

为了提高丙烷氨氧化制丙烯腈催化剂的性能 ,在Al-V -Sb -Ox 催化体系中逐步加入元素W ,P ,Mg ,B和Bi进行改性 ;采用孔结构分析 ,SEM ,XPS等手段表征了催化剂的孔结构、表面元素及元素化合态 ,与相应的催化性能相关联 ,研究了复合助剂元素对Al-V -Sb -Ox 催化剂的改性作用 .结果表明 :Al-V -Sb -Ox 催化剂体系是一种结构复杂、以无定形结构为主的表面不均匀的多孔催化剂 ,催化剂表面组成与体相组成相差较大 ;催化反应使表面元素分布明显改变 ,各助剂在复合情况下发挥的作用各有侧重 ,其中 ,W在提高催化剂比表面和催化活性方面作用突出 ,P可以增大催化剂的孔容和平均孔径 ,Bi则使V 。

The Al-Sb-V-O x catalysts promoted by one or several species among tungsten, phosphor, magnesium, boron and bismuth were characterized by pore structure analysis, powder X-ray diffraction, scan electron microscopy and X-ray photoelectron spectroscopy. The results of characterization were related to the performance of catalysts. It is shown that Al-Sb-V-O x catalyst is of structurally complex. The composition in the surfaces of catalysts is different from that in the bulks. And the population of the atoms in the surfaces of the catalysts was obviously changed with ammoxidation. The role of the promoters is favored in different sides. Tungsten was more effective on improving catalyst specific area and activity than the others. Phosphor could increase catalyst pore volume and average pore diameter. Bismith could decrease to a large degree the concentration of vanadium and antimony in the surface of the catalyst.