Preparation Of Alkynylated PVA-noble Metal Catalysts And Catalytic Performance For The Reduction Of 4-nitrophenol

Precious metals have unique stability,selectivity,high surface area characteristics,and excell ent structures.They stand out from many catalysts and have won wide attention in the cataly st industry.They are widely used in automobile exhaust treatment,fertilizer synthesis,fine c hemicals,petroleum smelting and many other fields.A large amount of researches have achi eved that the precious metal nanoparticles are uniformly distributed on stabilizers and a suita ble carrier should be selected to stabilize the metal nanoparticles.For example,the catalytic effect of Pd on Al₂O₃ is better than only PdIn this thesis,we use polyvinyl alcohol?PVA?as the matrix,propargylamine as the alkynyl source,carbamic acid as the modifier,and M?M=Pd,Pt,Au?as the catalytic particles,and modified grafting and blending methods to alkynylate PVA@M catalyst.Using infrared ray,nuclear magnetic resonance,and high-resolution transmission electron microscope to charac terize the graft structure and nanosphere microspheres,we get the the result that the graft deg ree of the alkynyl functional group was 52%,indicating that PVA was successfully alkynylat ed.The shape of Pd and Au Nanoparticles are spherical and uniformly distribute,and Pt nan oparticles sparsely distribute.The sizes of Pd nanoparticles are mainly between 3-7nm with a n average particle diameter of 5.01nm.The sizes of Pt nanoparticles are mainly between 2-5nm with an average particle diameter of 3.58.nm;The sizes of Au nanoparticles are mainly between 2-6nm,with an average particle diameter of 4.22nm.The alkynylated PVA@M was used to catalyze the reduction of 4-nitrophenol to study its c atalytic performance.The experimental results showed that the alkynylated-PVA@M did n ot show a high catalysis in the reduction reaction of 4-nitrophenol.We introduced graphene,MXene,multi-walled carbon nanotubes,three carbon-based material carriers,to optimize it,to obtain excellent performance from the supported catalyst of"alkynyl PVA@M/MWCN T".Based on different catalyst dosages,different pH values,and recycling and so on,the per formance of alkynylated-PVA@M/MWCNT for the reduction of 4-nitrophenol was evalua ted.The experimental results show that the alkynylated-PVA@Pd/MWCNT has the best c atalytic performance among the alkynylated-PVA@M/MWCNT,and it is more conducive to the reaction under acidic conditions.