Alumina support-stabilized nanoscaled vanadium–phosphorous mixed oxides as new catalysts for propane ammoxidation

详细信息    查看全文

• 作者：Ewelina Mikolajska^a ; ^{ejm@icp.csic.es"" rel=""nofollow} ; Elizabeth Rojas Garcia^a ; Ricardo Ló ; pez Medina^a ; Anna E. Lewandowska^a ; Jose Lu&#xed ; s G. Fierro^b ; Miguel A. Bañ ; ares^a ; ^{banares@icp.csic.es"" rel=""nofollow}
• 关键词：Support stabilized nanoscaled VPO ; Vanadium phosphates ; Propane ; Ammoxidation ; Acrylonitrile ; Alumina ; Surface vanadium oxide
• 刊名：Applied Catalysis A: General
• 出版年：2011
• 出版时间：19 September 2011
• 年：2011
• 卷：404
• 期：1-2
• 页码：93-102
• 全文大小：1545 K

文摘

Much attention has recently been devoted to the surface of bulk catalysts. It has been proved that the most critical phenomena occur at the surface, which differs significantly from the bulk. To evaluate the role of the bulk in VPO catalyst, vanadium and phosphorus were supported on γ-alumina by incipient wetness impregnation at a total V + P of two monolayers so that nanoscaled VPO phases (n-VPO) form on alumina, such size maximizes the surface-to-bulk ratio. Alumina support stabilizes V⁵⁺, which may be reduced, while V⁴⁺ predominates in bulk vanadyl pyrophosphate phase. In addition, the support modifies acid–base and textural properties. The presence of VPO nanocrystals supported on alumina (n-VPO) facilitates investigating the interaction between alumina-dispersed vanadia and VPO-lattice vanadium ions. Both, bulk and supported phases are active for propane ammoxidation affording acrylonitrile yields of 41 % and 48 % , respectively, at 500 °C. The yield to acrylonitrile per mass unit of VPO increases by 150 % at 500 °C in the alumina-stabilized n-VPO system when compared to the bulk VPO.