邻二甲苯氧化制苯酐催化剂载体钠迁移对催化剂稳定性的影响

探讨了以刚玉球为载体,V_2O_5-TiO_2为活性组份的邻二甲苯氧化制苯酐催化剂活性下降原因。发现由于刚玉球载体含钠量较高,催化剂在高温下长期反应,因载体中钠热迁移至活性组份中,与V_2O_5反应生成针状形态的钒酸钠化合物或固熔体,改变了V_2O_5在TiO_2上的分布状态和钒原子周围的配位结构、影响了催化剂的稳定性。

Effect of Migration of Sodium in Carrier on Activity of Catalyst for Oxidation of o-xylene to Phthalic Anhydride

The cause for reduction in activity of the catalyst with V_2O_5-TiO_2 as the active component for oxidation of o-xylene to phthalic anhydride was investigated. It was found that on prolonged reaction under high temperatures, the sodium, which was present in the alumina carrier in relatively high content, migrated to the active component and reacted with V_2O_5 to form needle-like or a solid solution of sodium vanadate with the molecular formula of Na_2O·V_2O_4·5V_2O_5, changing the state of distribution of V_2O_5 on TiO_2 as well as that of coordination around the vanadium atoms, and thus effecting the stability of the catalyst.