SiO_2负载MoVNbO复合氧化物催化剂上乙烷低温氧化制乙酸

Silica-Supported MoVNbO Complex Oxide Catalyst for Low-Temperature Oxidation of Ethane to Acetic acid

采用有机金属络合物浸渍表面反应技术制备了SiO2为载体的复合氧化物催化剂Mo3V1Nb0.3Ox/SiO2,并用N2吸附,IR,UVVis,TPR和微反技术研究了催化剂的表面结构、晶格氧的活性和对乙烷选择氧化反应的性能.实验结果表明,复合氧化物与SiO2表面以M-O-Si键连接,金属离子处在四面体和八面体配合物结构之中;含铌的表面复合氧化物中晶格氧的活性明显提高.在252℃,0.5MPa和空速2000h-1的反应条件下,乙烷与氧在Mo3V1Nb0.3Ox/SiO2催化剂上发生反应,生成乙酸和乙醛,乙烷的转化率达16.1%,产物乙酸和乙醛的总选择性为90.3%.

The Mo3VlNb0.3Ox/SiO2 catalyst was prepared by the surface modification of impregnated silica carrier with organometallic complexes. Its surface structure, activity of lattice oxygen, reducibility and catalytic performance for ethane selective oxidation were characterized by the techniques of N2 adsorption, IR spectroscopy, UV-Vis spectroscopy, temperature-programmed reduction and microreaction. The M-O-Si surface bonds are formed between the complex oxides and silica support, and the metallic ions of complex oxides are present in the coordinations of octahedron or tetrahedron. The activity of the lattice oxygen in the niobium-containing surface complexes in the Mo3V1Nb0.3Ox/SiO2 catalyst increases obviously. Under the optimum conditions of 252 ℃, 0.5 MPa and SV = 2 000 h^-1, ethane can be oxidized to acetic acid and acetaldehyde over the Mo3V1Nb0.3Ox/SiO2 catalyst with an ethane conversion up to 16.1% and a total selectivity for acetic acid and acetaldehyde of 90.3 %.