Based On Pd-loaded Organic Framework Nanocomposites Construction And Catalytic Performance Study

The use of nano-catalyzed particles to degrade dye wastewater is the most economical and efficient method for wastewater treatment.Among them,noble metal nanoparticles are the most ideal catalyst materials for treating dyes.However,due to the defects of precious metal nanoparticles which are easily agglomerated,the development of a carrier material with good dispersion and high specific surface area becomes the core problem to improve the catalytic performance of precious metal particles.Among many carrier materials,metal organic framework（MOF）and covalent organic framework（COF）materials can effectively improve the dispersion performance of nanoparticle catalysts due to their good mechanical strength,high specific surface area and easy modification,which make them ideal carrier materials.Based on this,the MOF@COF nanohybrid materials were constructed by compounding lanthanide MOF with imine COF,and the corresponding noble metal nanocomposite catalysts were prepared by loading palladium nanoparticles on this carrier,and the morphology and structure of the materials were characterized by SEM,XRD,TEM and XPS,and the catalytic degradation experiments and kinetics of various common organic dyes were investigated.The specific works are as follows.1.The straw-like Ce-MOF was synthesized with trimesic acid and cerium（Ⅲ）chloride,then amination was carried out,and-NH₂ was introduced,which was used as the core,and the COF synthesized from melamine and terephthalaldehyde was used as the shell.Hybrid preparation The Ce-MOF@COF composite material was obtained,and the Pd NPs were uniformly and stably loaded on the surface of MOF@COF to prepare the composite nanocatalyst Pd@Ce-MOF@COF.Then,the selectivity of the catalyst to different dyes was tested,and the single factor experiment and kinetic analysis of the catalytic degradation of methylene blue（MB）in aqueous solution were carried out,and the optimal catalyst dosage and Na BH₄ dosage were obtained.A linear relationship.Finally,replicate experiments and degradation mechanism studies were performed.2.Zn-MOF from zinc acetate and terephthalic acid was synthesized.4-amino-3-hydroxybenzoic acid was added to the Zn-MOF to obtain the Zn-MOF-NH₂ by adding free amino groups as the core,and the COF was used as the shell to prepare the Zn-MOF@COF composites with core-shell,then Pd NPs were introduced to prepare composite nanocatalysts Pd@Zn-MOF@COF.The degradation test and kinetic analysis of methyl orange,Congo red and carmine were carried out.The dosages of the optimum catalyst and of Na BH₄ were obtained.Finally,the repeated experiments and the degradation mechanism were carried out.3.Lanthanide MOF has excellent structure and affinity.In this chapter,lanthanum（III）and cerium（III）from the lanthanide metal family were used as metal sources to construct bimetallic MM-MOF(La_0.2Ce_0.8-MOF)with homobenzotriazole.La_0.2Ce_0.8-MOF@COF composite was prepared by amination with ethylenediamine to introduce-NH₂ and then hybridization with COF synthesized by melamine and terephthalaldehyde.And Pd NPs were uniformly and stably loaded onto the surface of MOF@COF to prepare the composite catalyst Pd@La_0.2Ce_0.8-MOF@COF.The degradation of 4-nitrophenol（4-NP）with methylene blue was tested and kinetically analyzed to obtain the optimal amount of catalyst required for its degradation and the amount of Na BH₄,and finally the degradation mechanism and reproducibility experiments on 4-NP were investigated.