Modulation of coordination environment on atomically dispersed Ir catalysts for highly-efficient reductive amination

The modulation of coordination environment on active metal atom as well as the cognition of selective-structure relationship have drawn widespread attention in heterogeneous hydrogenation reactions, but remain a big challenge. Here, we report 1 % Ir species supported on NiO nanosheet via a reduction process in hydrogen at various temperatures (donated as 1 %Ir/NiO-160, 1 %Ir/NiO-180 and 1 %Ir/NiO-200). Notably, the optimal catalyst 1 %Ir/NiO-180 exhibits an unexceptionable catalytic behavior (yield > 99 %) in furfural reductive amination reaction. A conjoint investigation based on AC-HAADF-STEM, XAFS and in situ CO-IR confirms the most abundant Ir - Ni coordination in 1 %Ir/NiO-180 catalyst, as well as mainly Ir - O coordination and Ir - Ir coordination in 1 %Ir/NiO-160 and 1 %Ir/NiO-200, respectively. Studies on structure-selective relationship based on in situ experiments and theoretical calculations further uncover that the Ir-Ni interfacial sites as intrinsic active centers simultaneously promote the adsorption of reaction intermediates (N-furfurylidenefurfurylamine) and the dissociation of NH3. Therefore, this process effectively promotes the reductive amination of reaction intermediate, leading to the production of furfurylamine (FAM) with a rather highly catalytic selectivity. This work provides an effective strategy for the modulation of coordination environment on active metal atom, which is constructive for the design and optimization of catalyst structure in the heterogeneous catalysis.