Ultrafine Palladium Nanoparticles Encapsulated In Porous Organic Polymers As Efficient Hydrogenation Catalysts

The design and construction of ultrafine metal nanocatalysts is one of the important research directions of nanocatalysis,which plays an important role in promoting the development of heterogeneous catalysis.Due to the ultrafine metal nanoparticles have large edge and angular atoms,thus endow them with superior activity for catalysis.Especially for precious metals,ultrafine noble metal nanoparticles?NMNPs?greatly increase their utilization.However,the higher surface energy of ultrafine nanoparticles leads to their severe agglomeration.Therefore,it is very urgent to design and synthesize a suitable supporter to effectively prevent the agglomeration of ultrafine nanoparticles.The porous organic polymers?POPs?and biomassa materials have high specific surface area,abundant heteroatoms content,adjustable pores and high thermal stability.When POPs is used as a catalyst supporter,the NMNPs can be dispersed and anchored,the particle dispersibility is improved,and the catalytic activity and stability of the catalyst are improved.In this work,a palladium-based nanocatalyst was used as the research background to explore a simple and efficient method for the preparation of NMNPs catalysts.The main research contents of this thesis are as follows:?1?We designed and synthesized a stable triazinly-pentaerythritol porous organic polymer?TP-POP?,which exhibits abundant hydrophobic pores and rich triazinyl groups.Then,the TP-POP was devoted to encapsulate highly dispersed ultrafine Pd NPs in its pores via a reverse double-solvents approach?RDSA?.The as-prepared Pd@TP-POP catalyst shows excellent catalytic activity in reduction of 4-nitrophenol and transfer hydrogenation of aromatic aldehydes under very mild conditions.?2?Separation and recovery of heterogeneous catalysts is also one of its important characteristics,and magnetic separation is usually the easiest and most effective way.The magnetic core-shell structured POP encapsulated ultrafine palladium nanoparticle catalyst synthesized in this work has improved the separation cycle of the catalyst.The Fe₃O₄@PDA@POP@Pd catalyst is applied to catalytic hydrogenation of an aryl nitro compound and over hydrogenation of an alkyne compound,which maintains excellent catalytic activity and stability while being simply recovered.?3?During the development of green sustainable energy,the work also synthesized biomass carbon fiber as a supporter-limited palladium-cobalt bimetallic nanocatalyst?PdCo/CCF?and applied it to catalytic hydrogenation reaction.This work is expected to provide a useful platform for improving the utilization of precious metals and developing highly efficient precious metal nanocatalysts for catalytic hydrogenation reaction.