用醇还原VOPO_4·2H_2O制备的VOHPO_4·0.5H_2O的择优取向性能

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

研究了用醇还原VOPO4 ·2H2 O制备的VOHPO4 ·0 5H2 O的晶面择优取向现象及其在正丁烷和空气混合气体中活化后 ,产物 (VO) 2 P2 O7的晶面择优暴露对正丁烷氧化制顺酐性能的影响 .以伯醇还原VOPO4 ·2H2 O制备的VOHPO4 ·0 5H2 O晶体 ,晶面择优取向于 (2 2 0 )面 ,晶型为玫瑰状或扭曲的片状聚集体 ;活化后的产物仅含(VO) 2 P2 O7相 ,其 (0 2 0 )晶面择优暴露 .以仲醇还原VOPO4 ·2H2 O制备的VOHPO4 ·0 5H2 O晶体 ,晶面择优取向于(0 0 1)面 ,晶型为平板片状体 ;活化后的产物由 (VO) 2 P2 O7,VOPO4 和无定形相组成 ,其中 (VO) 2 P2 O7相含量低 ,其(0 2 0 )晶面暴露少 .由苄醇、环己醇和 3 甲基 3庚醇还原VOPO4 ·2H2 O制备的VOHPO4 ·0 5H2 O的XRD谱与用仲醇制备的相似 .用一般方法 (V2 O5/异丁醇 /H3PO4 )制备的VOHPO4 ·0 5H2 O晶体不具有晶面择优取向性质 ,活化后得到的 (VO) 2 P2 O7的结晶度较低 .由正辛醇还原VOPO4 ·2H2 O制备的VOHPO4 ·0 5H2 O经活化后 ,对正丁烷氧化制顺酐的催化性能优于用仲辛醇和一般方法制备的VOHPO4 ·0 5H2 O .

VOHPO 4·0 5H 2O was prepared by reducing VOPO 4·2H 2O with various alcohols and then calcinated in n butane/air to produce the final catalysts. The preferential orientation of VOHPO 4·0 5H 2O and the influence of the preferential exposition of the plane of the final catalysts on catalytic oxidation of n butane to maleic anhydride (MA) were investigated. VOHPO 4·0 5H 2O with rose like or twist agglomerated type structure prepared by reducing VOPO 4·2H 2O with primary alcohol orientates preferentially the (220) plane, the final catalyst contains only (VO) 2P 2O 7 phase, the (020) plane is preferential exposition. VOHPO 4·0 5H 2O with platelet type structure prepared by reducing VOPO 4·2H 2O with secondary alcohol orientates preferentially the (001) plane, the final catalyst is composed of (VO) 2P 2O 7, VOPO 4 and amorphous phase, and the exposition of the (020) plane of (VO) 2P 2O 7 is less. The XRD patterns of VOHPO 4·0 5H 2O prepared from cyclohexanol, benzyl alcohol and 3 methyl 3 enanthol are similar to that prepared from secondary alcohol. VOHPO 4·0 5H 2O derived from V 2O 5/isobutanol/H 3PO 4 (ordinary method) has no the preferential orientation of the plane. The results show that the catalytic properties of the final catalyst prepared from 1 octyl alcohol for the oxidation of n butane to MA are superior to that of the catalyst derived from 2 octyl alcohol and ordinary method.