Study On Modification Of CuZrO₂ Catalysts By Graphene And Atmospheric Dehydrogenation Of Diethanolamine

The dehydrogenation of diethanolamine is a method for preparing iminodiacetic acid with simple operation,less pollution,and low cost.The traditional Cu/ZrO₂ catalyst has the advantages of high efficiency and low cost,but it is easily sinterable and easily deactivated by oxidation.In this paper,CuO/ZrO2-RGO catalyst precursors were prepared in one step by hydrothermal method using reduced graphene oxide?RGO?and ZrO₂ as a composite carrier.After hydrogen reduction,the Cu/ZrO₂-RGO catalyst with high activity and strong oxidation resistance was obtained.The influence of the introduction of RGO on the structure and properties of Cu/ZrO₂ catalyst was studied.On this basis,a multi-metal Cu-Ag-Fe catalyst was also prepared for exploring the feasibility of the dehydrogenation of diethanolamine at atmospheric pressure.In this thesis,firstly,graphite?GO?was prepared by Hummers method,and after being exfoliated into graphene oxide,it was reduced by hydrothermal method to obtain RGO.In hydrothermal reduction,the best reduction effect was obtained when water was used as the solvent,the pH of the solution was 10,the hydrothermal temperature was 170 ?,and the hydrothermal temperature was 6 h.The results of FT-IR,XRD,BET,and SEM indicate that the hydrothermal method can effectively reduce the graphene oxide.Under the optimum conditions,the RGO was obtain,with its C=O bond completely removed,and the C-O-C and-OH bonds were greatly reduced.The structure of RGO was transformed into graphite-like lamellar structure.Secondly,Cu/ZrO₂-RGO catalysts were prepared by hydrothermal method.With BET,XRD,SEM,H₂-TPR and other characterization methods and dehydration reaction tests of diethanolamine,the influence of the introduction of RGO on the microstructure,reduction performance,oxidation resistance and catalytic performance of Cu/ZrO₂ catalyst was studied.The characterization results show that the Cu/ZrO₂-RGO catalyst has a large specific surface area?109 m²/g?,good reducibility and oxidation resistance.The results showed that the IDA yield of Cu/ZrO₂ catalyst was 82.25%and the reaction time was 210 min,while the IDA of Cu/ZrO₂-RGO catalyst was 96.77%and the reaction time was 150 min.It can be concluded that RGO can effectively improve the catalytic performance of the catalyst.Finally,the Cu/ZrO₂-RGO catalyst and a Cu-Ag-Fe polymetallic catalyst were used to dehydrogenate diethanolamine under atmospheric pressure.The reaction test results showed that the activity of the Cu/ZrO₂-RGO catalyst was insufficient at atmospheric pressure to catalyze the dehydrogenation of diethanolamine.When water was used as the solvent,the Cu-Ag-Fe catalyst catalyzes the dehydrogenation of diethanolamine without iminodiacetic acid generated,but in the absence of solvent or mesitylene as solvent,the yield of iminodiacetic acid was 0.89%and 0.49%,respectively.After using RGO as carrier,the yield of iminodiacetic acid was increased to 10.97%,indicating that RGO can increase the dehydrogenation activity of the catalyst.CuFe₂O₄,AgFeO₂ were formed between Cu and Fe,Ag and Fe in Cu-Ag-Fe catalyst respectively,the complexes make the dispersibility of the active metals better,the synergy between the metals stronger,and the catalytic activity of the catalyst higher.After the introduction of RGO as a carrier,this synergistic effect is enhanced,and the activity of the catalyst is further improved.