逆水煤气变换耦合乙烷脱氢反应中载体对氧化铬催化剂性能的影响

Effect of supports on the catalytic performance of chromium oxide catalysts for the coupling of reversed water-gas shift reaction with the dehydrogenation of ethane to ethylene

研究了在逆水煤气变换耦合乙烷脱氢反应中担载型氧化铬催化剂的活性,考察了多种载体对于催化剂反应性能的影响。结果表明,不同的载体所担载的氧化铬催化剂具有不同的催化性能。其中二氧化硅担载的氧化铬催化剂具有较高的乙烷转化率和乙烯选择性,在700℃时分别达到30.7%和96.5%。CO2的作用是通过与H2反应促进乙烷脱氢、并减少催化剂表面积炭。运用XRD、TPR、XPS、UV-DRS和微量吸附量热技术对催化剂体相与表面结构、表面酸性和铬物种价态等进行了表征,结果显示催化剂表面酸中心适当的强度、数量和分布有利于乙烷的活化和催化转化,Cr3+和Cr6+物种是反应的活性中心。

The coupling reaction of the dehydrogenation of ethane to ethylene with reversed water-gas shift reaction was studied over chromium oxide catalysts. And the effect of support on catalytic activity was also studied. The results show that the support exerts a quite different effect on catalytic behavior. Cr/SiO2 catalyst exhibits an excellent performance in this reaction with 30.7% ethane conversion and 96.5% ethylene selectivity. The function of CO2 is to abstract H2 and to resistant coke formation during dehydrogenation of ethane. XRD, TPR, XPS, UV-DRS spectroscopy and micro-calorimeter technique are used to investigate the nature of active site of catalysts. Characterization indicates that the distribution of chromium oxide on supports and surface chromium species structure are influenced by the nature of supports. The acidity/basicity and redox property of catalysts determines the catalytic activity in the dehydrogenation of ethane under CO2. Cr3＋and Cr6＋ species on the surface of catalysts were proposed to be the active sites for the reaction.