| CrOx/SiO2催化剂上丙烷在CO2气氛中脱氢反应的研究 |
| Dehydrogenation of Propane over CrOx/SiO2 Catalysts under CO2 Atmosphere |
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| 摘要: 采用XRD、UV-vis DRS、ESR和微分吸附量热等技术,考察了铬担载量分别为2.5、5和10wt%的CrOx/SiO2催化剂的结构、表面性质和氧化还原性能。结果表明,催化剂表面上存在多种Cr的氧化态和聚集形式。随着Cr担载量从2.5wt%到10wt%的逐渐增大,催化剂表面占主导地位的Cr物种由CrO3单体转为多聚CrO3和Cr2O3晶相。在CO2气氛中催化剂对丙烷转化率和丙烯选择性的大小顺序为2.5wt%CrOx/SiO2>5wt%CrOx/SiO2>10wt%CrOx/SiO2,反应过程中的原位ESR和UV-visDRS测定结果表明,催化剂表面的反应活性中心为Cr5+,Cr5+可由催化剂预处理过程中Cr3+的氧化及丙烷反应过程中CrO3单体的还原产生,在反应中CO2可使Cr3+重新氧化为Cr5+. |
| 关键词: CrOx/SiO2催化剂 丙烷脱氢 CO2 Cr5+活性中心 |
| 基金项目: 国家自然科学基金资助课题(No.29973013);国家重点基础研究规划项目(G1999022408)课题. |
| Abstract: The surface structure and redox properties of CrOx/SiO2 catalysts with various Cr loadings of 2.5, 5 and 10wt% have been investigated by XRD, UV-vis DRS, ESR and microcalorimetric adsorption methods.It was found that chronia occurs with different oxidation states and different coordination numbers on the surface of the catalysts.With Cr loadings increasing from 2.5wt% to 10wt%, the dominant surface Cr species change from chromate to polychromate and Cr2O3 cluster.The order of propane conversion and selectivity to propane for the propane dehydrogenation reaction under CO2 atmosphere over CrOx/SiO2 catalysts is 2.5wt%CrOx/SiO2 > 5wt%CrOx/SiO2 > 10wt% CiOx/SiO2. The results of ESR and UV-vis DRS measured during reaction process indicate that the active center of CrOx/SiO2 catalysts for the reaction is Cr5+ species, which is probablely generated from Cr3+ species oxidizing during the calcination and chromate reducting during the reaction.The role of CO2 is to reoxidize Cr3+ to Cr5+ in the reaction. |
| Keywords: CrOx/SiO2 catalysts propane dehydrogenation CO2 Cr5+ active center |
| 投稿时间：2000-03-06 修订日期：2000-04-13 |
| 摘要点击次数: 1165 |
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| 邹琥,葛欣,李明时,上官荣昌,沈俭一.CrOx/SiO2催化剂上丙烷在CO2气氛中脱氢反应的研究[J].无机化学学报,2000,16(5):775-782. |
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