Synthesis Of Catalysts With Nanoparticles Supported On Metal Organic Frameworks And Its Catalytic Performance Of CO₂ Hydrogenation

In the CO₂ hydrocatalytic reaction,porous MOFs with carboxylic acid as the connective framework would be an advantageous support instead of metal oxide carrier of catalyst bacause its secondary building units similar to metal oxide;Metal nanoparticles?MNPs?can have different performance by adjusting their morphology,size and distribution,In order to combine the excellent properties of both MOF and MNPs,we studied the design and assembly of catalyst MNPs@MOF with core-shell structure by loading different MNPs into the core and surface of MOF,it can effectively prevent MNPs from agglomerate and deactivation,and later we researched the catalytic performance of catalysts in CO₂ hydrogenation reaction.1.The spherical catalysts Au@UIO-66 and Au@Pd@UIO-66 with core-shell structure was synthesized,UIO-66 as carrier was shell and Au NP or Au@Pd NP was core respectively;the effect of PVP on synthesis of catalysts was studied,and ultrathin Pd atomic layer on the surface of the Au@Pd can promote the formation of core-shell structure and have the effect of nanocrystalization on products;uniformly and dispersed catalysts containing Pt were obtained after adsorbing Pt NPs on the surface of UIO-66.The catalytic results showed that Pt/Au@Pd@UIO-66 has high catalytic activity and high CO selectivity in the RWGS reaction because of the strong interaction between UIO-66 and MNPs,meanwhile,core-shell structure canpre vents the agglomeration of MNPs after the collapse of UIO-66 at high temperature and UIO-66 can transform into ZrO2 which is still a good catalyst carrier.2.Four core-shell catalysts with different cubic Pd NPs loads were synthesized:Pd3.4@UIO-66,Pd7.7@UIO-66,Pd14@UIO-66 and Pd20@UIO-66,the change of Pd content will affect integral uniformity and dispersity of the catalysts,and Pd14@UIO-66 has the highest activity in CO₂ hydrocatalytic reaction;the selectivity of the product varies with the change of the Pd load,the selectivity of CO and CH4 reached the lowest and highest points respectively,namely high content of cubic Pd NPs could inhibits the production of CO and promotes the production of CH4.3.Ru@Pd and Pt@Pd with core-shell structure was synthesized with cubic Pd as the template;Due to the differences in the stability of the two metals?Pd and Pt,Pd and Ru?,the square hollow nanoparticles of Pt and Ru can be obtained by selective removal of Pd using the etchant.The addition of PVP could contribute to the dispersion of Pt NCs in the MOF precursor solution and MOF will grow around Pt NCs as core.when the composites MNCs@MOF was synthesised.This shows the formatiom of a dual functional material MNCs@MOF with MOF micropores and MNCs mesopore is feasible by loading hollow particles in MOF.