Synthesis And Application Of Highly Stable S-modified Mesoporous Carbon Confined Ru Nano-catalyst

1,2,3,4-Tetrahydroquinoline is an important chemical intermediate for drugs,dyes and other biologically active molecules,so the efficient and selective hydrogenation of quinoline to produce1,2,3,4-Tetrahydroquinoline is There are broad application prospects in the synthesis of fine chemicals and drugs.However,due to the strong adsorption of quinoline and its hydrogenation products on the metal nanocatalyst,it is difficult to obtain the target product with high selectivity due to excessive hydrogenation of the substrate,as well as the problems of catalyst poisoning and metal loss.In this topic,a series of highly stable sulfur-doped mesoporous carbon-supported Ru catalysts were prepared using coordination-assisted block copolymer self-assembly methods.At the same time,quinoline selective hydrogenation was used as a probe reaction to explore the catalyst's reactivity center.XRD,TEM and other characterization results show that the coordination of mercapto groups and the mesoporous confined environment can effectively disperse and stabilize Ru nanoparticles;the metal reduction and carrier pyrolysis process proceed simultaneously to form metal nanoclusters.Part of the atoms in the nanoparticles are embedded in the pore walls,and some of the atoms are exposed in the mesoporous channels,which inhibits their loss and reunion.The electronic structure of ruthenium nanoparticles was explored through XPS and other characterization methods.The results showed that there was an electron transfer between the sulfur species and the metal Ru,and the sulfur species had a stronger ability to withdraw electrons.By changing the molar ratio of metal to ligand,the proportion of Ru⁰ in the catalyst changed significantly;the proportion of Ru⁰ in the catalyst Ru/OMSC-0.504%reached the highest value of55.42%.Chemical reaction kinetics experiments show that the doping of sulfur can reduce the activation energy of the reaction to varying degrees,and also changes the adsorption strength of the catalyst to the substrate,so that the adsorption reaches the optimal value.Under the reaction conditions of 130?and H₂ pressure of 4 MPa,the catalyst Ru/OMSC-0.504%has the optimal catalytic activity for the selective hydrogenation of quinoline.The initial reaction rate can reach 159.15 mmol·mmol_Ru^-1·h^-1.The selectivity to the product 1,2,3,4-tetrahydroquinoline is greater than 99%.According to the XPS characterization results,it can be seen that the proportion of Ru⁰ in this catalyst is the highest?55.42%?,so it provides more active sites for the reaction.Both"sulfhydryl capture"experiment and the ICP test did not detect the loss of ruthenium,indicating that the sulfur-doped mesoporous carbon-supported Ru catalyst has good catalytic stability.The catalyst Ru/OMSC-0.504%has undergone six catalytic cycles,and the initial rate of the reaction does not change significantly,indicating that the catalyst has good resistance to poisoning.