硅铝比对Co/SSZ-13催化CO_(2)氧化乙烷脱氢制乙烯反应性能的影响  

Effects of Si/Al on the catalytic performance of Co/SSZ-13 catalysts for CO_(2)oxidative ethane dehydrogenation to ethylene

作　　者：王樱 陈铭 钟智勇 叶代启 陈礼敏 WANG Ying;CHEN Ming;ZHONG Zhiyong;YE Daiqi;CHEN Limin(School of Environment and Energy,South China University of Technology,Guangzhou 510006;National Engineering Laboratory for VOCs Pollution Control Technology and Equipment,Guangzhou 510006;Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control(SCUT),Guangzhou 510006)

机构地区：[1]华南理工大学环境与能源学院,广州510006 [2]挥发性有机物污染治理技术与装备国家工程实验室,广州510006 [3]广东省大气环境与污染控制重点实验室,广州510006

出　　处：《环境科学学报》2023年第10期331-342,共12页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.22276060)。

摘　　要：采用浸渍法制备了不同硅铝比载体负载的钴基催化剂,探究了硅铝比对CO_(2)氧化乙烷脱氢(CO_(2)-ODHE)性能的影响.NH_(3)-TPD、Raman、H_(2)-TPR、XPS等表征结果表明,硅铝比对载体酸碱性的改变会显著影响催化剂上Co物种的落位、结构和氧化还原性能.降低硅铝比会提高载体的弱酸位点的数量,而酸量的提高改变了催化剂表面钴物种的存在形式,即提高催化剂表面Co^(2+)的占比.同时,不同的钴物种对催化剂酸性的贡献存在差异,分子筛上的Co^(2+)与羟基醇的相互作用会提高催化剂的酸性,而大量存在的CoAl_(2)O_(4)及Co_(3)O_(4)会在一定程度上降低催化剂的酸性.催化剂上钴物种的存在形式及酸性共同作用于CO_(2)-ODHE的活性,大量的Co^(2+)及适量的酸性位点是保持高乙烷转化率和乙烯收率的关键,适量的Co_(3)O_(4)则可促进CO_(2)的转化,进而使乙烷通过ODHE路径产乙烯,但过高的酸性将导致乙烷严重积碳.The cobalt-based catalysts supported on SSZ-13 with different silica-aluminum ratios were prepared through impregnation to investigate the effect of silica-aluminum ratio on CO_(2)oxidative ethane dehydrogenation(CO_(2)-ODHE).NH_(3)-TPD,Raman,H_(2)-TPR,and XPS characterizations show that the silica-alumina ratio changes the acidity of supports,significantly affecting the settlement and structure of Co species and redox performance of catalysts.Reducing the silica-alumina ratio will increase the acidity of the support,which increases the amount of Co^(2+)on catalyst surface.In addition,cobalt species contributes differently to the catalyst acidity.The Co^(2+)species interacts with silanol groups and increases the catalyst acidity,while large amounts of CoAl_(2)O_(4) and Co_(3)O_(4) reduce it.Accordingly,the form of cobalt species and the catalyst acidity together contribute to the CO_(2)-ODHE activity.A large amount of Co^(2+)and the proper amounts of acidic sites are essential to achieve high ethane conversion and ethylene yield.The proper amount of Co_(3)O_(4) promotes CO_(2)conversion,subsequently leading to ethylene production through ODHE reaction.Besides,excessive acidity results in severe carbon deposition of ethane.

关 键 词：CO_(2) 乙烷氧化脱氢 Co基催化剂 硅铝比 酸碱性 

分 类 号：X701[环境科学与工程—环境工程]