Preparation Of Noble Metal Based Nano Catalyst And Its Catalytic Performance For Selective Hydrogenation

Hydrogenation is not only used to produce various organic chemicals in chemical production,but also used as a refining method to improve the purity of chemical products.However,at present,most of the catalysts for catalytic hydrogenation are supported catalysts.Due to the small size and high surface energy of the active components,it is easy to aggregate and fall off,so it is difficult to achieve high conversion rate,excellent selectivity and good stability while obtaining high conversion frequency?TOFs?.In view of the above problems,this paper mainly carried out the design and controllable preparation of new nano catalysts based on noble metal nanoparticles and metal organic framework?MOF?and their research work in catalytic hydrogenation.For the alkyne semi-hydrogenation,in this paper,the metal organic framework of the zirconium metal node?UiO?with adjustable hydrophobicity and electron absorption ability is used as the support,and the palladium?Pd?nanoparticles are used as the active component to construct the sandwich structure catalyst of UiO@Pd@UiO precisely for the alkyne semi-hydrogenation.In the semi-hydrogenation of phenylacetylene,the coated porous hydrophobic UiO not only enriches phenylacetylene around Pd nanoparticles,but also promotes the hydrogenation reaction,making the TOF value reach 17608 h^-1.In addition,there is an interface electron transfer between Pd nanoparticles and UiO,which reduces the adsorption energy of Pd nanoparticles on styrene and effectively prevents the hydrogenation reaction.When phenylacetylene is completely converted,the selectivity of styrene reaches 93.1%.The activity and selectivity of the catalyst did not decrease after five consecutive catalytic cycles.In addition,the catalyst also showed high activity and selectivity in the hydrogenation of alkynes with different end groups and inner chains.By changing the number of benzene rings on the organic ligands,we can customize the support at the molecular level,which provides an important reference for the design of heterogeneous catalysts with high performance.For phenol hydrogenation,Pt@MIL-101?Cr?catalyst was prepared by using Pt nanoparticles as the active component,MIL-101?Cr?as the support,and Pt nanoparticles were confined in the pores of MIL-101?Cr?by double solvent method.This restriction not only makes the catalyst achieve complete conversion of phenol under mild conditions,but also the selectivity of cyclohexanol reaches 100%.In addition,its activity and selectivity remain unchanged during five cycles of the catalyst.The preparation method of the catalyst provides a way for the synthesis of heterogeneous catalyst with high performance and high stability.