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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＋。
The structure, surface properties and redox properties of CrOx / SiO2 catalysts with 2.5, 5 and 10 wt% chromium loadings were investigated by XRD, UV-vis DRS, ESR and differential calorimetry. The results show that there are many oxidation states and aggregated forms of Cr on the catalyst surface. With the increase of Cr loading from 2.5wt% to 10wt%, the Cr species dominated on the surface of the catalyst changed from CrO3 monomer to polycrystalline CrO3 and Cr2O3 crystal phases. The order of catalyst to propane conversion and propylene selectivity in CO2 atmosphere is 2 in size. The results of in-situ ESR and UV-vis DRS measurements show that the reaction center of catalyst surface is Cr5 +, and Cr5 + can be controlled by the catalyst pretreatment process Cr3 + Of the oxidation and propane reaction process CrO3 monomer reduction in the reaction of CO2 Cr3 + can be re-oxidized to Cr5 +.