Zhao Yifan,Li Wensi,Rehman Mooeez Ur,Wang Shengping,Li Guobing,Xu Yan
A series of N-modified Ru/N x -AC catalysts were prepared by ammonia treatment method and applied in dioctyl phthalate hydrogenation, which is a cascade reaction system involving partial hydrogenation of aromatic ring and the further saturated hydrogenation of the formed intermediate bis(2-ethylhexyl) cyclohexene-1,2-dicar-boxylate (DH 4 ) to dioctyl di-2-ethylhexylcyclohexane-1,4-dicar-boxylate (DEHCH). N doping was found to be able to increase the nitrogen-containing pyridine groups on the activated carbon (AC) surface, resulting in the abundance of binding sites for anchoring Ru and exceptionally enhancing the dispersion of Ru nanoparticles. Furthermore, the N-modified Ru/N 12 -AC catalyst exhibited a significantly higher turnover frequency value (1260.06 h −1 ) than Ru/AC catalyst (913.64 h −1 ). It was deduced that the presence of the pyridine groups could improve the adsorption of intermediate DH 4 by promoting the coverage of DH 4 on the catalyst surface. The environment of surface-enriched DH 4 accelerated the reaction rate of DH 4 hydrogenation and increased the selectivity to DEHCH. Therefore, the cooperation between highly dispersed Ru nanoparticles and pyridine groups supports remarkably enhanced the activity and selectivity. In addition, the Ru/N 12 -AC catalyst presented excellent catalytic activity and versatility in the hydrogenation of other phthalates such as dimethyl phthalate, diethyl phthalate, and dibutyl phthalate, demonstrating its prospective application in phthalate esters hydrogenation. Graphical abstract
Description N-doping exceptionally improved Ru dispersion and the adsorption of the intermediate product in DOP hydrogenation, leading to a higher activity and selectivity to saturated product.
Ru/AC catalyst used in acetylene hydrochlorination reaction has several drawbacks such as poor dispersion, metal loss, serious carbon deposition, and insufficient active sites. To address these issues of traditional Ru/AC, in this study, the supported Ru-L x /AC catalysts were synthesized by the coordination of ruthenium precursor and several structural triazine ligands. The complexation of heteroatomic structure to Ru atom formed a local active domain, which is more conducive to the synergistic adsorption and activation of the initial reactants, and further optimizes the reaction microenvironment. The spatial topological structure with conjugated structures effectively promoted the transfer of electrons between the heteroatoms and the ruthenium precursors, facilitating the stabilization of active Ru species. The newly developed synthetic process also increased dispersion of reaction components and impeded the sintering of ruthenium components promoted by the local structural forces. The optimum Ru-1,3,5-triazine/AC (Ru-L 1 /AC) catalyst exhibited 162% higher acetylene conversion than the benchmark Ru/AC catalyst. The significantly improved activity and stability of the optimized catalyst will have a huge application prospect in industry.
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