醇还原VOPO_4·2H_2O制备VOHPO_4·0.5H_2O的活化研究

Activation of VOHPO_4·0.5H_2O Prepared by Reducing VOPO_4·2H_2O with Alcohol

研究了醇还原 VOPO4 · 2 H2 O制备的 VOHPO4 · 0 .5H2 O,在正丁烷和空气的混合气体中活化后 ,醇对产物物相组成的影响。由伯醇制备的 VOHPO4 · 0 .5H2 O活化后 ,产物中( VO) 2 P2 O7相的结晶度和含量较高 ;随着伯醇碳原子数的增加 ,活化后产物 ( VO) 2 P2 O7的无序度增加 ;仲醇制备的 VOHPO4 · 0 .5H2 O活化后 ,最终产物中 ( VO) 2 P2 O7的含量和结晶度较低 ,且有较多的无定型和 VOPO4 相生成。研究表明 ,正戊醇 (正辛醇 )制备的 VOHPO4 · 0 .5H2 O活化后 ,正丁烷的转化率和顺酐的选择性均优于仲戊醇 (仲辛醇 )和常规方法制备的 VOHPO4 · 0 .5H2

The calcination of VOHPO 4·0.5H 2O prepared by reducing VOPO 4·2H 2O with alcohols in n butane/air has been investigated. The studies of XRD show that, in VOHPO 4·0.5H 2O prepared with alcoh l ols and calcinated under identical conditions ( 430°C , n butane/air=1.5/98.5, V/V ), the crystallinity and content of (VO) 2P 2O 7 phase are high. The degree of the disorder along the [020] cleavage plane of (VO) 2P 2O 7 increases with the number of carbon atom of alcohols used to prepare VOHPO 4· 0.5H 2O . VOHPO 4·0.5H 2O prepared with alcoh 2 ols and calcinated under same conditions is composed of (VO) 2P 2O 7, amorphous phase and VOPO 4 phase and the crystallinity and content of (VO) 2P 2O 7 are lower than that prepared by using alcoh l ol. The results of experiment show that the catalytic oxidation properties of the final catalyst of VOHPO 4·0.5H 2O prepared with pental l ol (or octyl alcoh l ol) is better than those with pentan 2 ol (or octyl alcoh 2 ol) and normal method (V 2O 5+isobutanol+H 3PO 4). Disorder along the [020] plane of (VO) 2P 2O 7 catalyst considerably enhances the activity of the selective oxidation of n butane to maleic anhydride (MA).