Preparation Of Carbon Supported Cobalt Base Catalyst And Its Catalytic Performance In The Reduction Of P-nitrophenol

Nitrophenol(NP)is difficult to be biodegraded under natural conditions and is listed as a priority control substance in water in China due to its high chemical stability and complex composition.Aminophenol(AP)as an intermediate of analgesics and pyrolysis drugs can be obtained by catalytic reduction of NP.Therefore,the removal of NP and the conversion of NP into AP are of great significance for environmental pollution control and sewage treatment.ZIFs and its derivatives are widely used in gas storage,adsorption,drug delivery,sensors,biological imaging,supercapacitors,catalysis and other fields due to their unique advantages.Therefore,it is of great practical significance to choose a suitable carrier to fix metal nanoparticles uniformly on the carrier as a low-cost,efficient and easily separated catalyst for catalytic reduction of NP.In this work,ZIFs with different morphologies were prepared by solvothermal method,and then the ZIFs were pyrolyzed under a certain atmosphere to make the metal ions reduced to metal nanoparticles and uniformly anchored in the nitrogen-doped carbon matrix.By replacement reaction,noble metal nanoparticles were loaded on the nitrogendoped carbon matrix,which made nanocomposites with high catalytic efficiency and easy separation and recovery.This work mainly includes the following research contents:(1)Preparation and catalytic performance of carbon matrix supported cobalt nanoparticles composite catalystZIF-L was grown on the carbon cloth by solvothermal method to make the foliated ZIF-L fixed on the carbon cloth(ZIF-L/carbon cloth)and then the nitrogen-doped carbon matrix loaded cobalt nanoparticles(Co@N-C/carbon cloth)were obtained by high temperature pyrolysis at different temperatures.The results showed that the porous carbon matrix was formed after high temperature pyrolysis and the cobalt nanoparticles were anchored in the matrix.The size of cobalt nanoparticles was about 11 nm,which avoided the aggregation of cobalt nanoparticles.The composite material was used in the catalytic reduction reaction of 4nitrophenol(4-NP),and the catalytic process was monitored by UV.The test results showed that the composite material obtained from pyrolysis at 600℃ showed the best catalytic effect,and the reaction equilibrium constant Kapp was 5.53×10-3 s-1.The conversion efficiency of 4NP was still about 72%after repeated for 5 times and the composite catalyst fixed on the carbon cloth is easy to separate and recover is expected to achieve continuous catalysis.(2)Preparation and catalytic performance of cobalt and gold nanoparticle composite catalysts supported on carbon matrixZIF-67 was also prepared by solvothermal method,and then the nitrogen-doped carbon matrix supported cobalt nanoparticles(Co@N-C)were obtained by high-temperature pyrolysis at 800℃.The gold nanoparticles were anchored on the nitrogen-doped carbon matrix by replacement reaction of Co@N-C with different amounts of chloro-gold acid solution under certain conditions then the composite catalyst(Au-x/Co@N-C)was obtained.The results showed that the porous carbon matrix was obtained after high temperature pyrolysis and the cobalt nanoparticles were anchored in it.The gold nanoparticles were successfully anchored on the surface of Co@N-C through replacement reaction,and the particle size of the gold nanoparticles was about 9 nm.The composite material was used in the catalytic reduction of 4nitrophenol(4-NP)and the catalytic process was monitored by UV.The test results showed that Au-1/Co@N-C had the best catalytic efficiency and the K app of Au-1/Co@N-C was up to 37.46×10-3 s-1.The conversion efficiency of 4-NP remained at 89%after 5 cycles.And the magnetic nanocomposites are easy to recycle.