Preparation Of Biomass-Based Catalysts By Hydrothermal Synthesis Method And Its Performance For Wet Oxidation

In recent years,with the rapid development of science and technology and economy in my country,the process of industrialization and urbanization has been accelerated,and a large number of industrial plants have been built and put into operation.At the same time,clean production and environmental governance have achieved great results.It is particularly important to develop in harmony with nature.Catalytic wet air oxidation（CWAO）has a good effect on the treatment of organic,toxic and harmful wastewater with high concentrations that are refractory to degradation.The core of this technology is the catalyst,so the research and development of catalysts with excellent performance,good stability and low price is the goal of many researchers.Among them,copper-based catalysts,as one of the non-precious metal catalysts,have good catalytic performance and lower price than noble metal catalysts,which has great research significance.However,copper-based catalysts have the problems of poor stability and easy dissolution of active components in the process of wet oxidation of wastewater.At present,there are few studies on the stability of copper-based catalysts,and further research is needed.In this thesis,biomass-based hydrothermal carbon catalysts with different structures were prepared,and their adsorption performance,catalytic oxidation performance and stability to phenol were investigated.The catalyst structure was characterized by SEM,TEM,XRD,XPS,N₂ physical adsorption-desorption and other characterization methods to explore the structure-activity relationship of the catalyst,which would provide an experimental basis for the preparation of better copper-based catalysts.The main contents and conclusions of this thesis are as follows:（1）Nano-carbon microspheres were prepared by hydrothermal method with glucose,and the supported copper-based catalyst was prepared by using it as a carrier.Studies have shown that the copper component in the catalyst was in the form of a mixture of Cu O and Cu₂O.As the calcination temperature increased,the proportion of bivalent copper oxides increased,and the proportion of monovalent copper oxides decreased.The pore structure is dominated by micropores,and it had a large specific surface area and abundant oxygen-containing functional groups.When the calcination temperature was 700℃,the adsorption and oxidation performance of the catalyst reached the best.When the phenol concentration was 200 mg/L and the catalyst addition amount was 3 g/L,the phenol adsorption amount reached 64 mg/g.At 140℃and the initial oxygen pressure of 0.5 MPa,the simulated wastewater with a concentration of 1000 mg/L of phenol was treated.The conversion rate of phenol was 99.8%,and the conversion rate of COD reached 92.7%.（2）The carbon-coated copper nano-microsphere catalyst was prepared by the hydrothermal-post-coating method,and its morphological structure and catalytic wet oxidation degradation performance of phenol were investigated.The research found that the carbon-coated copper nano-microsphere structure material has good thermal stability,uniform size,about 100 nm in diameter,and good monodispersity after being calcined at700℃.Mainly,with the increase of copper doping content,the conversion rate of phenol and COD showed an increasing trend.When the doping content of copper was 10%,the conversion rate of phenol could reach 99.9%,and the conversion rate of COD could reach89.1%.（3）The concentration of 5 g/L sodium chloride and sodium sulfate has no obvious effect on the adsorption and oxidation performance of the catalyst.In the acid solution of p H 3.71 and the supported and coated catalysts with a copper doping content of 5%,the leaching amounts of copper components were 3.0 mg/L and 1.4 mg/L,respectively.After catalytic wet oxidation of phenol,the copper leaching amount of the coated catalyst was reduced from 14.0 mg/L to 0.5 mg/L compared with the supported catalyst.