Although nickel dispersed in mesoporous aluminosilicates are efficient catalysts for the oligomerization of ethylene, the nature of the active nickel sites still remains controversial. Here we applied in situ FTIR-CO spectroscopy during reaction with ethylene combined with reaction kinetics with online MS analysis of reaction products to unravel the nature of the active nickel species in working mesoporous Ni-Al-MCM-41 catalysts. The results revealed that isolated ion-exchanged Ni²⁺ cations are irreversibly blocked during the initial reaction stages leaving unsaturated Ni²⁺ cations grafted on silanols and at the surface of small (confined) NiO nanoparticles as the active species in the pseudo-steady state. The low activity of these species in pure silica materials suggested a promotional role of aluminum in the Al-MCM-41 matrix on enhancing the activity of Ni²⁺ sites, probably through a close interaction between Al species and nearby Ni²⁺ sites, as inferred from quantitative ²⁷Al MAS NMR and FTIR spectroscopies.

尽管分散在中孔铝硅酸盐中的镍是乙烯低聚的有效催化剂，但活性镍位的性质仍存在争议。在这里，我们在与乙烯反应过程中应用了原位FTIR-CO光谱，并结合了反应动力学和反应产物的在线MS分析，以揭示在工作介孔Ni-Al-MCM-41催化剂中活性镍物种的性质。结果表明，在初始反应阶段，分离出的离子交换的Ni ²⁺阳离子被不可逆地阻止，从而使不饱和Ni ²⁺阳离子接枝在硅烷醇上和小的（受限的）NiO纳米颗粒的表面上，成为拟态中的活性物种。-稳定状态。这些物质在纯二氧化硅材料中的低活性表明铝在Al-MCM-41基质中对增强Ni ²⁺活性具有促进作用，这可能是由于Al物种与附近的Ni ²⁺部位之间存在密切的相互作用，由定量的²⁷ Al MAS NMR和FTIR光谱推断。