逆水煤气变换耦合乙烷脱氢反应中助剂对Cr/SiO_2催化剂性能的影响

Effect of promoters on Cr/SiO_2catalysts for coupling of reversed water-gas shift reaction with dehydrogenation of ethane to ethene

分别制备了以Mn、Ce、Cu、Zn、K等为助剂的Cr/SiO2催化剂,考察了助剂在逆水煤气变换耦合乙烷脱氢制乙烯反应中对Cr/SiO2催化剂反应性能的影响。结果表明,高温下Mn的加入有利于催化活性的提高,Cr-Mn/SiO2催化剂显示了较好的催化活性。在740℃、n(CO2)/n(C2H6)=7的条件下,乙烷转化率为47%,乙烯选择性为99%。XRD、XPS、UV-DRS和TPR技术的表征表明催化剂表面存在Cr3+、Cr6+、Mn4+物种,Mn的加入使得催化剂还原性能增强,有助于反应过程中氧化还原循环的进行,提高了反应活性。

The coupling reaction of ethane dehydrogenation with reversed water-gas shift reaction over Cr/SiO2 catalysts was studied.The Cr/SiO2 catalyst promoted by Mn oxide has already been found to be active and selective in the reaction at around 740 ℃,with the selectivity to ethylene of about 99.7% at 47.7% ethane conversion.XPS results showed that Cr6＋,Cr3＋ and Mn4＋ occupied on the surface of the catalysts.The addition of Mn benefited the redox cycle between reactants and catalyst and enhanced reaction activity.