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本文对前文所表征过的5个Cu/SiO_2催化剂进行了烯醛缩合反应制异戊二烯的活性评价.并对其反应后未再生的样品进行了XRD及XPS表征,关联表征与反应结果发现这些纯铜系催化剂上存在的两种铜组分(CuO和孤立Cu~(2+)),可被反应物甲醛还原为金属铜或Cu_2O.从反应初始活性数据来看,似乎可以认为Cu_2O是烯醛反应的活性相之一,且很可能是活化甲醛的中心.而金属铜则对生成异戊二烯不起活性作用.Cu_2O所起的可能是一种弱酸弱碱双功能位的作用.文中还对具有较长寿命的N-115(二氧化硅担载铜锑催化剂)和N-218(二氧化硅担载铜系催化剂)二催化剂寿命试验前后的活性数据进行了对比,并从酸碱催化的角度推论了影响铜系催化剂寿命的两个可能因素.
In this paper, the activity of isoprenal condensation reaction of five Cu / SiO 2 catalysts was evaluated, XRD and XPS were used to characterize the reaction of the unmodified samples, and the correlation analysis and reaction results were found The two copper components (CuO and isolated Cu 2+) existing on these pure copper catalysts can be reduced by formaldehyde to copper or Cu 2 O. From the initial activity data, it seems that Cu 2 O can be considered as One of the active phases of alkene reaction, and it is likely to be the center of activated formaldehyde, while copper does not play an active role in the formation of isoprene.Cu_2O may play a role as a weakly acidic and weak base bifunctional site. The activity data before and after the life test of N-115 (silica-supported copper antimony catalyst) and N-218 (silica-supported copper catalyst) catalysts with longer lifetimes were also compared and analyzed from acid The base catalysis point out two possible factors that affect the life of copper-based catalysts.