The Design Of Functional Group-Controlled Hollow Double-Shell MOFs Supported Pt Nanoparticles For Studying On Selective Hydrogenation Of Cinnamaldehyde

In the past decades,metal-organic frameworks(MOFs)assembled from metal ions and organic ligands through coordination bonds have received widespread attention as a new class of porous crystalline materials.The design of the hollow structure of the double-shell MOF controlled by functional groups in this paper can not only use the hollow structure to accelerate the mass transfer rate of the reaction molecules,but also regulate the outer shell layer with functional groups to have different morphologies,flakes or Block shape,which also plays a role in accelerating the mass transfer rate.Among the many MOF structures,ZIF-8 is often chosen as the carrier matrix for supporting metal nanoparticles due to its simple synthesis method and good thermal stability.Due to the high selectivity of Pt metal nanoparticles for C=O hydrogenation,they are often used in the selective hydrogenation of unsaturated aldehydes and ketones.UiO-66 can be synthesized with ligands with different functional groups(X=Br,NH2,NO2,H),and has different morphological characteristics.Numerous studies have shown that different morphologies lead to different properties because the active sites and mass transfer rates exposed by different morphology catalysts are different.Therefore,we have designed a catalyst with different morphological characteristics and supporting Pt nanoparticles with double-shell hollow MOFs.ZIF-8 is used as the inner layer to disperse Pt nanoparticles in a restricted area,and UiO-66-X is the outer layer.To regulate the overall morphology of the hollow catalyst.In order to investigate the effect of morphology on the catalytic effect of the catalyst,this group of catalysts were used to catalyze cinnamaldehyde,and the selective catalytic results of the reactants were compared and compared.The first part:using sulfonated polystyrene nanospheres as a template,growing a layer of ZIF-8 on the surface,supporting Pt nanoparticles on ZIF-8 by dipping method,and then growing a layer of UiO-66 on the outer layer by water bath method-66.Finally,the polystyrene template was removed with a polar solvent to obtain a catalyst with the structure Void@ZIF-8@Pt@UiO-66.The catalyst was used in the reaction of cinnamaldehyde hydrogenation to evaluate its activity and selection.The second part:Based on the synthesis ideas in the first part,the outer UiO-66 was replaced with UiO-66-X(X=Br,NH2,NO2),so that the catalyst has a different morphology.This series of catalysts are also used in the hydrogenation of cinnamaldehyde to study the law of catalytic reactions.It was found that under the same reaction conditions,Void@ZIF-8@Pt@UiO-66-NO2 has the best catalytic activity,which is attributed to the loose and porous sheet-like structure of UiO-66-NO2,which accelerates the mass transfer rate for the reaction.