Study On MOFs-Membranized Core-Shell HZSM-5@MOFs Loaded（Pd,Pt）and Their Catalytic Properties For CO₂ Conversion

The advantages of Zr-based metal organic frameworks,such as high stability,large specific surface area and regular pore size,make it widely used in catalysis,adsorption,separation and other fields.MOFs can be combined with functional materials(such as SiO2,MNPs,MOFs,zeolites,etc.)to form SiO2@MOFs,MOFs@MOFs,MNPs@MOFs,and zeolite@MOFs composite materials,and anchor MNPs by using MOFs to form multifunctional composite materials.In this paper,encapsulating HZSM-5 into Zr-based UIO-66-NH2 and UIO-67 to form the HZSM-5@MOFs structures,respectively.The HZSM-5@MOF s/MNPs multifunctional catalyst can be obtained by combining HZSM-5@MOFs with MNPs,and their catalytic performances for CO2 conversion were studied.HZSM-5 nanocrystals(NCs)with regular hexagonal prisms were prepared.And encapsulating HZSM-5 NCs into UIO-66-NH2 were controlled by dual solvents(EtOH,DMF),resulting in core-shell HZSM-5@UIO-66-NH2 materials with continuous UIO-66-NH2 membrane.The effects of ZrCl4/EtOH(or H2BDC-NH2/DMF)concentration,EtOH/DMF ratios,the HZSM-5 dosage and reaction time on UIO-66-NH2 coating HZSM-5 were investigated,and related characterizations of the synthesized HZSM-5@UIO-66-NH2 were carried out.The prepared HZSM-5,UIO-66-NH2 and HZSM-5@UIO-66-NH2 loading Pd NPs,respectively,were used for CO2 conversion,and the catalytic performances of UIO-66-NH2/Pd,HZSM-5@UIO-66-NH2/Pd and HZSM-5/Pd in CO2 conversion were compared.Also,the catalytic ability of HZSM-5@UIO-66-NH2/Pd under different conditions was discussed.The results showed,the catalytic performance of HZSM-5@UIO-66-NH2/Pd was better than that of UIO-66-NH2/Pd and HZSM-5/Pd.And at reaction condition:320℃,the ratio of CO2/H2 being 1:3,2 MPa,HZSM-5@UIO-66-NH2/Pd had the best performance,showing 17.1%CO2 conversion rate and 92.2%CO selectivity.In my study,embedding HZSM-5 into UIO-67 to form HZSM-5@UIO-67 hybrid material was regulated by dual solvents(EtOH,DMF).The effects of EtOH/DMF ratios,UIO-67 precursor concentration and the amounts of HZSM-5 on the synthesis of HZSM-5@UIO-67 were studied.The results demonstrated that double-solvent(EtOH-DMF)method was also suitable for HZSM-5 embeded into UIO-67.Because of the affinity between Pt NPs and UIO-67,the Pt NPs could be loading on UIO-67 to obtain HZSM-5@UIO-67/Pt hybrid material with dispersed Pt NPs on the surface.