Study On The Application Of High Entropy Molecular Sieve Catalyst In Supercritical Catalytic Oxidation Of Coking Wastewater

Coking wastewater is one of the high concentration toxic and harmful wastewater,which is difficult to be fully degraded by the ordinary treatment process to meet the discharge requirements.The discharge of the water into the environment will cause harm to water organisms and human health.It is more and more important to develop an efficient and green process to treat high concentration coking wastewater with the increasingly strict requirements of environmental protection.As one of the best treatment methods for high concentration organic wastewater,The Catalytic Oxidation in Supercritical Water(CSCWO)has a good effect on the removal of coking wastewater.However,the harsh reaction conditions of supercritical reaction have great limitations on this technology.A highly efficient and stable catalyst can improve the catalytic effect,reduce the reaction conditions and reduce the reaction time,which will have special significance for the industrial promotion of the CSCWO technology.A kind of catalyst for supercritical catalytic degradation of coking wastewater was prepared in this paper on the basis of summarizing the status of CSCWO technology and its catalytic mechanism and was studied comprehensively with coking wastewater from a petrochemical plant in Wuhan about its characteristics.The main conclusions are as follows:(1)The catalyst is supported by silica-alumina molecular sieve,and has the best promoting effect on the stability of the carrier when modified with rare earth element YB.The catalyst was prepared by impregnation sintering method,in which V,W and Ti were fixed on the molecular sieve support at 800?for 6h.Taking the catalyst weight loss rate as the research object,the optimal ratio of the active component in the catalyst weight was determined.It was found that the weight loss rate of the catalyst was the lowest when the mass fraction of the active element corresponding to the reagent V=3.82%,W=1.00%and Ti=6.25%.(2)Catalyst were analyzed in coking wastewater degradation temperature,pressure,reaction time,oxygen ratio on the removal rate of COD and NH₃-N and the effect of combination of response surface optimization method,establish regression model,analysis of the interaction of the various factors,catalyst for the supercritical catalytic degradation of coking wastewater removal rate of COD and NH₃-N affects the same order,followed by temperature(T)>reaction time(t)>EO>pressure(P);The optimal reaction conditions for COD removal were as follows:temperature 448.16?,pressure 24.19MPa,time 16.19s,peroxide ratio 2.45,and the removal rate was99.97%at this time.The optimal removal rate of NH₃-N was 98.74%under the following conditions:temperature 436.21?,pressure 29.38MPa,time 1.99s,and peroxide ratio 3.34.(3)The regression analysis showed that the activation energy of the coking wastewater was 97.56 k J/mol without catalyst,and 23.89 k J/mol under catalyst condition.The activation energy was significantly reduced with the addition of catalyst.The reaction kinetic equation of the degradation of the coking wastewater under supercritical catalysis was calculated.(4)The quantum mechanical parameters of characteristic pollutants such as phenol and indole were analyzed by Material Studio,a simulation software of density functional theory,and the reaction process of degradation of characteristic pollutants in coking wastewater was speculated.(5)Combined the change of porosity before and after the reaction with the dissolution rate of active components in supercritical catalytic coking wastewater reaction,the value of the catalyst in industrial application was evaluated.