The Preparation Of Novel Metallic Catalyst Stabilized By Modified Poly (Propylene Imine) Dendrimer And The Application For The Hydrogenation Of Diene Copolymers

Nitrile-butadiene rubber(NBR)and styrene-butadiene rubber(SBR)have relatively poor anti-aging capability due to carbon-carbon double bond in the molecular structures.Presently,the anti-aging capability can be effectively improved by hydrogenating the unsaturated carbon-carbon double bond to saturated carbon-carbon single bond.However,the hydrogenation catalysts possess some disadvantages in terms of catalytic performance,selectivity,separation and recovery capability.Therefore,the development of a novel type of catalyst with high catalytic activity,favorable selectivity,low cost and easy recovery capability is an important subject in the field of catalytic hydrogenation.The double bonds in the nitrogen-containing 15-membered triolefinic macrocyclic ligands are excellent electron donators for the transition metallic atoms,and the macrocyclic ligands have high antioxide stabilization and tend to coordinate with metallic atoms to form complexes,which are beneficial to stabilize and recover metal.Dendrimers have stereoregular,highly branched and precise structures.The internal cavity can effectively encapsulate the metal particles.In addition,the surface modification of the dendrimer can also transfer the catalytic active center to the dendrimer surface,which is more likely to contact with the substrates.By combining the advantages of macrocyclic ligands and dendrimer,several novel catalysts having high loading capacity,local concentration and catalytic activity were prepared.The main contents of the thesis are as follows:1.15-memberedtriolefinic macrocycle(MAC)was synthesized by using2,4,6-triisopropyl-benzenesulfonamide,4-(3-bromopropyl)benzenesulfonamide and1,4-dibromo-2-butene as materials through nucleophilic substitution reaction between the amino group and bromine atom.The products were characterized by FT-IR,1H-NMR,MALDI-TOF-MS and elemental analysis.2.Hybrid dendrimers(G2-M,G3-M)with MAC on its surface were synthesized by the nucleophilic substitution reaction between amino group in dendrmers andbromopropyl groups in MAC.The G2-M and G3-M were characterized by FT-IR,1H-NMR and elemental analysis.3.G2-M(Rh3+xRu3+10-x)and G2-M(Rh3+xPd2+10-x)were prepared by coordination between G2-M and RuCl3·3H2O/RhCl3·3H2Oand RhCl3·3H2O/Pd(OAc)2 respectively.The Rh3+,Ru3+ and Pd2+ were stabilized on the surface of G2-M by the coordinate bonds between MAC and metal ions.There was a synergistic effect between the bimetalic ions in G2-M(Rh3+xPd2+10-x)and G2-M(Rh3+xRu3+10-x).Besides,G3-M was used to coordinate with RhCl3·3H2O to prepare G3-M(Rh3+).The prepared catalysts were analyzed and characterized by 1H-NMR,UV-vis,XRD and XPS.The catalytic activity of G2-M(Rh3+xPd2+10-x)and G2-M(Rh3+xRu3+10-x)bimetallic catalysts demonstrated higher catalytic activities than that of G2-M(Rh3+x)/G2-M(Ru3+10-x)and G2-M(Rh3+x)/G2-M(Pd2+10-x)in the hydrogenation of NBR and SBR.The active species Rh[(PPh3)3]1+ can be generated by ligand exchange between triphenylphosphine(PPh3)and G2-M(Rh3+),which can significantly promote the hydrogenation of NBR and SBR.The hydrogenation degree of NBR and SBR obtained by catalytic hydrogenation of G2-M(Rh3+)can reach above 99.8%.The residual amounts of Rh in HNBR and HSBR catalyzed by G2-M(Rh3+)were 55 ppm and 33 ppm,respectively.The Rh0 generated from the Rh ions can be recaptured by the macrocycles in G2-M,but the Rh0 had poor interaction with PPh3 to form active species,resulting in significant catalytic decrease for the recovered G2-M(Rh3+).The recovery rate of Rh in HNBR and HSBR catalyzed by G2-M(Rh3+)was much higher than that of the traditional catalyst-Rh(PPh3)3Cl.G2-M(Rh3+)and G3-M(Rh3+)had similar catalytic capability.However,the Rh residue in HNBR and HSBR catalyzed by G3-M(Rh3+)were higher than those of G2-M(Rh3+).3.The G3-M(Pdx Pt10-x)nanoalloy were prepared by ligand exchange method between G3-M and the complexes of Pd(PPh3)4/Pt(PPh3)4.G3-M(PdxPt10-x)(x = 7,5,3)displayed higher catalytic efficiency than that of single metal G3-M(PdxPt10-x)(x =0,10)for the hydrogenation of NBR and SBR.The hydrogenation degree of NBR andSBR catalyzed by G3-M(Pd7Pt3)can be 45.5% and 38.1% respectively.Because of the larger molecular weight of SBR than NBR,the catalyst is more difficult to contact with SBR than NBR,resulting in the higher hydrogenation degree of NBR than that of SBR under the same conditions.The residual amounts of Pd and Pt metal in HNBR obtained by catalytic hydrogenation of G3-M(Pd7Pt3)were 55 ppm and 58 ppm,respectively,and the recovery of total metals were 80.2%.The residual amounts of Pd and Pt metals in HSBR obtained by the first catalytic hydrogenation of G3-M(Pd7Pt3)were 40 ppm and 43 ppm,respectively,and the recovery of total metals was 85.5%.4.Acylated polypropylene imine dendrimers(G2-A and G2-P)were synthesized by one-step reaction throughG2-PPI/benzoyl chloride and G2-PPI/propionyl chloride respectively.The structure and composition of G2-A and G2-P were characterized by FT-IR,1H-NMR,13C-NMR and elemental analysis.G2-A(Rh3+)and G2-P(Rh3+)were prepared by the coordination between G2-A(P)and RhCl3·3H2O.The 13C-NMR spectra indicated the the characteristic peaks of the carbon atoms adjacent to the quaternary amine group completely shifted to high field.The coordination ratio of quaternary amine group and Rh3+ was 3:1.Since the recovery capability of G2-M is stronger than that of G2-A and G2-P,the HNBR and HSBR catalyzed by G2-A(Rh3+)and G2-P(Rh3+)demonstrated higher Rh residues than those of G2-M(Rh3+).