Adsorptive Removal Of Odor Gaseous Contaminants Over MOFs Materials And Gas Sensing Performance Over MOFs Derived Materials

Metal organic frameworks(MOFs)which are constructed from metal ions and organic ligands are emerging as a class of very important materials offering high levels of porosity with considerable control over pore size and compositioa Such properties play a crucial role in functional applications in gas storage or separation,sensing,catalysis,drug delivery and porous template.In this thesis,various MOFs with different compositions were prepared to explore the effects of structure and component on the adsorptive performance of some typical indoor gaseous contaminants(CH3SH,HCHO).The physical structures and chemical properties have great influence on the adsorptive behaviour of various MOFs.Moreover,The ZnO/ZnFe2O4 hollow cube composites with heterogeneous structure were synthesized by a facile strategy through simple and direct pyrolysis of Fe?-modified Zn-based metal-organic frameworks.The research results are summarized as:(1)Copper-based metal organic frameworks(HKUST-1)with controllable size and shape were synthesized using hydrothermal and precipitation method.The as-prepared HKUST-1 materials were used to remove gaseous methyl mercaptan(CH3SH).The morphology and texture of HKUST-1 materials have great influence on the performance of the adsorption process.The HKUST-1 material synthesized by hydrothermal method exhibited the highest sulfur compound adsorptive capacity among the synthesized HKUST-1 materials.The XRD?XPS and FTIR changes of HKUST-1 during CH3SH capturing process,indicated that strong interaction between the unsaturated copper sites and-SH group which finally formed CuS and gave rise to obvious damage to the MOF structure.The color of HKUST-1 changed from blue to dark green during the adsorption process.Only HKUST-1 has effective adsorption ability toward low concentration CH3SH among the M-BTC series MOFs including Cu2+,Mn2+,Fe3+,Co2+,Ni2+ Zn2+ as central ion.(2)In order to solve the existing problems of HKUST-1 material including poor resistance to humidity and loss of material during prilling process,HKUST-1 membrane was growth on Al2O3 substrate using thermal seeding-mediated secondary growth strategy(denoted as HKUST-1 @Al2O3).The synthesis method successfully avoided the nucleation of HKUST-1 crystals in the solution phase.The HKUST-1 membrane is continuous,without any cracks,pinholes and its thickness is about 20 ?m.The BET surface area of HKUST-1 @Al2O3 is about 284 m2/g with microporous and mesoporous pores.The loading amount of HKUST-1 is 7.5 wt%of HKUST-1 @Al2O3.The excellent dispersion of HKUST-1 membrane on the Al2O3 substrate enhance the use efficiency of HKUST-1 and the capacity is 108.6 mg CH3SH/g HKUST-1.The hydroscopicity of porous alumina could reduce the adsorption of water on HKUST-1 membrane leading to good water resistibility.(3)UIO-66-NH2?IRMOF-3?MIL-53(Fe)-NH2 and their counterparts UIO-66?MOF-5?MIL-101(Fe)were prepared by hydrothermal method by using ZrCl4?Zn(NO3)2?FeCl3 and NH2-BDC?BDC as raw materials.The amino modified MOFs including UIO-66-NH2?IRMOF-3 and MIL-53(Fe)-NH2 can adsorb low concentration HCHO while the MOFs without amino including UIO-66?MOF-5 and MIL-101(Fe)can hardly adsorb HCHO.Among the synthesized MOFs UIO-66-NH2 has the highest HCHO capacity which is 19.9 mg/g UIO-66-NH2 while IRMOF-3 and MIL-53(Fe)-NH2 have low HCHO capacity.Mannich reaction took place between HCHO and UIO-66-NH2 which was confirmed by FTIR investigation.(4)The ZnO/ZnFe2O4 hollow cubes composites with heterogeneous structure were synthesized by a facile strategy through simple and direct pyrolysis of Fe?-modified Zn-based metal-organic frameworks.The as-synthesized ZnO/ZnFe2O4 hollow cubes have well-defined cube morphology with?2 ?m and multiple porous shell constructed by interpenetrated ZnO and ZnFe2O4 heterogeneous nanoparticles.A omparative sensing performance investigation between ZnO/ZnFe2O4 and singular ZnO demonstrated that,in contrast with ZnO,the ZnO/ZnFe2O4 showed significantly enhanced chemical sensing response low-concentration acetone.The optimum operating temperature is 250 ? of the synthesized ZnO/ZnFe2O4.Furthermore,the Zn0/ZnFe2O4 hollow cubes exhibited good reproducibility and selectivity towards gaseous acetone.The enhanced sensing performance of the MOF-derived ZnO/ZnFe2O4 hollow cubes is ascribed to the unique hierarchical structure with high specific surface area,abundant exposed active sites with surface-adsorbed oxygen species and heterojunctions formed at the interfaces between ZnO and ZnFe2O4.