Synthesis And Application Of Cu-based MOFs And Their Derived Composite Materials

In recent years,researches concerning the synthesis and application of metal-organic frameworks?MOFs?and their derived composite materials are getting more and more attention.Owing to their advantanges,MOFs have been applied in many fields.Moreover,metal@C composite materials derived from the pyrolysis of MOF precursors are showing potential applications in various catalytic reactions,due to the adjustable particle size and uniform dispersion of active metal apecies.This dissertation focuses on the synthesis of Cu based MOF materials and their pyrolytic derivatives,systematically characterizes the synthesized materials,and studies their application in adsorption desulfurization and transfer hydrogenation of nitroaromatic hydrocarbons.A bimetallic-organic porous material?Cu/Co-BTC?with a paddle-wheel structure has been successfully synthesized.The prepared Cu/Co-BTC samples were investigated in thiophene?TP?adsorption from model gasolines by the fixed bed adsorption method at 303 K.The bimetallic Cu/Co-BTC with a Cu/Co ratio of 174 displayed significantly improved adsorption desulfurization performance,showing an increase in breakthrough volume by 30%compared with HKUST-1.And the bimetallic Cu/Co-BTC showed a slight loss in breakthrough volume by only 5%after regenerating 8 times,displaying an excellent regeneration property.The addition of toluene or cyclohexene as a competitor in the model gasoline led to a decline in desulfurization performance,especially when cyclohexene was added.HKUST-1 is one of the earliest synthesized and widely studied MOF materials.It is necessary to explore the possibility of directly using it as a catalyst for the hydrogenation of nitrobenzene.In this paper,HKUST-1 was used to catalyze the hydrogenation of nitrobenzene,employing sodium borohydride as the reducing agent.The results showed that HKUST-1displayed the maximum nitrobenzene conversion of 67%with 100%selectivity to aniline under the optimal reaction conditions.But the regeneration property of the catalyst is poor,the conversion was significantly reduced when HKUST-1 was used for 5 times.Novel Cu based catalysts Cu@C-x,where Cu nanoparticles?NPs?embedded in porous carbon materials,were prepared by one-pot pyrolysis of HKUST-1 at different temperatures in Ar atmosphere.Cu@C-400 was screened to be the optimal catalyst by considering the preparation and the catalytic activity.It catalyzed the reduction of nitroarenes to the corrresponding aniline.The control experiments demonstrated that Cu⁰ was the active sites.When the aromatic nitro compounds with reducible groups,were tested in this catalytic hydrogenation,an excellent selectivity approaching 100%was achieved.In the recycling experiment,the conversion of nitrobenzene is still 99%after the catalyst is reused 7 times,showing that Cu@C-400 is an effective and stable catalyst for the reduction of nitrobenzene.In order to investigate the effect of N doping in carbon material on the catalytic hydrogenation of nitro compounds,Cu@NC-400 material was synthesized by pyrolyzing the precursor Cu₂?BDC?₂?BPY?in Ar atmosphere and was studied in hydrogenation of nitro compounds.The results showed that no promotion effect was observed for the catalytic activity of N doping Cu@NC-400 compared with that of Cu@C-400 catalyst.A significant advantage of Cu@NC-400 catalyst is that it displayed high selectivity for the reduction of halogenated nitrobenzene.Finally,in the reaction system of isopropanol and KOH,it was found that the nitrobenzene can be completely converted by adjusting the reaction conditions,the type and dosage of solvent without using any metal catalyst,and aniline was the product in dominant amount.In the experiment of substrate expansion,it was found that there is still a certain deficiency in the chemical selectivity of the reaction substrate.