Preparation And Catalysis Of Metal Nanoparticle/Metal-Organic Framework Composite Catalyst

Recently,metal nanoparticles/MOF composite materials have attracted extensive attention in catalytic fields due to the significant synergistic effect in them,which induce an important new direction of the functional study on MOFs.Although they have already exhibit intriguing application prospect,some serious issues such as complicated preparation procedures,easy aggregation of nanoparticles,week interface interaction between MOF and nanoparticles,etc.still need to be addressed.As a basic reaction in the field of catalysis,catalytic hydrogenation has pivotal position in national economy.In this respect,the semi-hydrogenation products of phenylacetylene were important intermediates in the production of foamed plastics.The products of carbonyl hydrogenation of cinnamaldehyde were widely used in cosmetics and pharmaceutical industries.Therefore,it is important research significance to design and synthesize catalysts with high activity and high selectivity for selective hydrogenation of phenylacetylene and cinnamaldehyde.Addressing the problems above,we proposed three methods to prepare nanoparticles/MOF composite materials.The first is to use MOF⁺technology,that is,the surface reaction technology of“phenol-Fe?III?”interaction.Secondly,metal nanoparticles without stabilizers by spray technology.The third is the combination of the above two kinds of technology.On such a basis,we were prepared three types of catalysts and studied their performance in different catalytic hydrogenation furtherly.The Specific research-related was as follows:?1?We selected Zn-MOF-74 as the carrier,use Pd as the active metal and employed FeSO₄·7H₂O to be the reducing agent for a simple in-situ preparation of Zn-MOF-74/?Pd/Fe₂O₃?complex catalyst through the MOF⁺technology.The catalyst could well maintain the integrity and porosity of the MOF framework,and showed excellent properties in alkenes and phenylacetylene catalytic reactions.Compared with traditional methods for the preparation of complex catalysts,this method provided a unique and novel idea.?2?With sodium borohydride as the reducing agent,we prepared the monodispersed Pd NPs solution through the MOF⁺technology,and then prepared Pd/Zn-MOF-74 complex catalyst by Impregnation with Zn-MOF-74 as the carrier.The catalyst showed great selective catalytic performance toward phenylacetylene and propiolic acid.Selectivity of phenylacetylene reached 92%with TOF value at 98.1 h^-1.Theoretical calculation also noticed the coordination between the open Zn?II?metal sites in Zn-MOF-74 material and the C?C bonds in phenylacetylene structure,that activate the C?C bond to achieve high selective hydrogenation of Styrene.?3?With sodium borohydride as the reducing agent,we first used the spray technology to prepare the monodispersed Pt NPs solution,and then employed the MOF⁺technology with Zn-MOF-74 as the carrier to prepare Co-MOF-74/?Pt/Fe₂O₃?complex catalyst.The catalyst showed excellent selective catalytic capability in the catalytic hydrogenation of cinnamaldehyde with TOF value as high as 245.6 h^-1 and the selectivity of cinnamaldehyde up to 95%.The characterization results reveal the strong space-limiting effect between the metallic nano-particles and the MOF support,which can significantly reduce the electron cloud density of the platinum nanoparticles and activate the C=O double bond.Meanwhile,the well-developed pores in the catalyst structure can provide a strong spatial confinement effect,further improving the performance of the catalyst.