Hydrogenation of olefins and aromatics is of significance for fuel processing and hydrogen storage, and developing nickel (Ni) catalyst highly active at low reaction temperature is the key to low the process cost. Herein we developed an ammonium citrate assisted impregnation method to fabricate loaded Ni catalyst (NiM-2) for hydrogenation. The Ni²⁺ species are anchored on the support MCM-41 strongly and evenly in form of Ni-citrate complex via the H-bonding between Si-OH group of MCM-41 and –COO^- of citrate. During reduction, the carbon layers temporarily formed by carbonization of citrate species inhibit the transfer and sintering of Ni species, and finally induces ultra-small metallic Ni nanoparticles after carbon layers slow decomposition by Ni species. Low coordination numbers and strong electron interaction between small metallic Ni nanoparticles and MCM-41 support upshift the d-band center of metallic Ni atoms. In hydrogenation, the small particle size and easier reduction for oxidized Ni species provide abundant active sites for reaction, and the upshifted d-band center induces strongly adsorption and activation of C = C bonds, which is confirmed for the first time in our work. As a result, the catalyst exhibits superior activity compared with reported and commercial Ni-based catalysts for hydrogenation of olefins and aromatics. Specifically, the catalyst with higher Ni loading (18%) exhibits good activity under room temperature and 0.1 MPa for hydrogenation of dicyclopentadiene and are comparable to Pd catalysts, making it as one of the best non-precious metal catalysts for hydrogenation reaction. And also, NiM-2 shows extremely high stability.

烯烃和芳烃加氢对于燃料加工和储氢具有重要意义，开发低反应温度下高活性的镍（Ni）催化剂是降低工艺成本的关键。在此，我们开发了一种柠檬酸铵辅助浸渍方法来制造用于加氢的负载镍催化剂（NiM-2）。Ni ^{2+物质通过 MCM-41 的 Si-OH 基团和柠檬酸盐的 –COO -}之间的氢键以 Ni-柠檬酸盐络合物的形式牢固且均匀地锚定在载体 MCM-41 上。在还原过程中，碳层 柠檬酸盐物种碳化暂时形成的纳米粒子抑制了镍物种的转移和烧结，最终在碳层被镍物种缓慢分解后诱导出超小的金属镍纳米粒子。小型金属 Ni 纳米粒子和 MCM-41 之间的低配位数和强电子相互作用支持金属 Ni 原子的 d 带中心上移。在氢化过程中，氧化镍物质的小粒径和更容易的还原为反应提供了丰富的活性位点，并且上移的d带中心诱导了C=C键的强烈吸附和活化，这是我们的工作中首次得到证实。因此，与报道的和商用的用于烯烃和芳烃加氢的镍基催化剂相比，该催化剂表现出优异的活性。具体来说，高Ni负载量(18%)的催化剂在室温和0.1 MPa下对双环戊二烯加氢表现出良好的活性，与Pd催化剂相当，使其成为加氢反应最好的非贵金属催化剂之一。而且，NiM-2表现出极高的稳定性。