针对目前丙烷非氧化脱氢中铬系催化剂活性位点存在的问题，通过调控不同铬基前驱体负载在MCM-41上来建立活性位点与催化性能之间的构效关系。利用XPS、H₂-TPR、XRD、UV、H₂-TPR等表征手段对催化剂的价态、活性物种的存在形式等进行表征。结果表明，制备的3种铬基催化剂都有单体的Cr （Ⅵ）、聚合的Cr （Ⅵ）以及块状的Cr₂O₃。Cr/MCM-41（H₈CrN₂O₄）产生更多Cr （Ⅵ）；催化剂所形成的单体的Cr （Ⅵ）促进活性的提升；与之相反，聚合的Cr （Ⅵ）和块状的Cr₂O₃阻碍催化剂的性能。单体的Cr （Ⅵ）在遇到丙烷迅速被还原成配位不饱和的Cr³⁺、Cr²⁺，进一步说明单体的Cr （Ⅵ）是铬系催化剂应用于丙烷非氧化脱氢的活性位点的前体。

In view of the controversial problem of the active sites of chromium-based catalysts for non-oxidative dehydrogenation of propane,the structure-activity relationship between active sites and catalytic performance is established by adjusting the loading of different chromium-based precursors on MCM-41.XPS,H₂-TPR,XRD,UV,in-situ TPR,and other characterization methods are utilized to analyze the valence state of the catalyst and the existence of active species.Results show that the three chromium-based catalysts prepared all have monomeric Cr(Ⅵ),polymerized Cr(Ⅵ),and massive Cr₂O₃.Among them,XPS and H₂TPR results show that Cr/MCM-41(H₈CrN₂O₄) produces more Cr(Ⅵ);XRD.UV and Raman results prove that the monomer Cr(Ⅵ) formed by the catalyst promotes the improvement of activity.In contrast,polymerized Cr(Ⅵ) and massive Cr₂O₃ hinder the performance of the catalyst.Finally,in-situ TPR proves that monomer Cr(Ⅵ) is rapidly reduced to coordinate unsaturated Cr³⁺ and Cr²⁺ when encountering propane.It is further illustrated that the monomeric Cr(Ⅵ) is the precursor of the active site of the chromium-based catalyst used in the non-oxidative dehydrogenation of propane.

张哲玮(1996-),男,硕士研究生,研究方向为材料催化,2205520710@qq.com