Development And Performance Study Of Catalysts For Catalytic Oxidation Of Phenol And Ammonia Wastewater From Coal Chemical Industry

With the development of coal chemical industry,phenol and ammonia containing wastewater emission has increased dramatically,the phenol and ammonia containing wastewater has the characteristics of high concentration,high toxicity,high pollution and refractory degradation.Therefore,it is necessary to develop advanced coal chemical industry phenol-ammonia wastewater treatment technology.At present,the traditional treatment route has a long process and large investment,and is not suitable for enterprises with low phenol-ammonia content and low water volume.Therefore,low-cost catalytic oxidation technology has become an appropriate route to treat this type of wastewater.Furthermore,high-performance catalysts are the core and foundation of catalytic oxidation.In this thesis,the catalytic wet oxidation removal of ammonia-nitrogen was firstly studied,and the Ru/CMK-3-N catalytic was prepared.The effects of synthesis method,metal precursor,reaction temperature,reaction time and Ru loading amount on the catalytic wet oxidation performance of ammonia-nitrogen were investigated.Then,in this thesis,Fe and N co-doped ordered mesoporous carbon materials were used to activate peroxymonosulfate（PMS）,M-cresol was degraded by advanced oxidation technology（SR-AOP）based on sulfate radical.The effects of Fe and N doping on the activation performance of PMS were analyzed,the effect of the p H value and the concentration of PMS on the performance of the catalyst was investigated,and the degradation pathway and mechanism of M-cresol of the catalyst were explored.The results are shown as follows:In the study of catalytic wet oxidation treatment of ammonia nitrogen,compared with the IM-AH and IM-RC catalysts synthesized by the traditional impregnation method,the DMH-AH catalyst synthesized by the surfactant（DATB）-assisted hydrothermal method has the best catalytic performance,under the reaction conditions of 200 ^oC and 6 h,the NH₃ conversion and N₂ selectivity of the latter catalyst were97.5%and 99.9%,respectively.This is mainly because,on the one hand,during the metal loading process of DMH-AH,the two ends of DAT²⁺are respectively connected with the negatively charged carrier（CMK-3-N）and the metal precursor(Ru Cl₆^2-),which inhibits the aggregation of ruthenium nanoparticles;on the other hand,during high-temperature calcination process,the carbon deposition of surfactant still hinders the aggregation of ruthenium nanoparticles,so as to effectively ensure that DMH-AH has smaller Ru nanoparticle size and higher dispersion.In addition,the influence of valence state and relative content of metal on catalytic performance was further studied.It was found that,compared with IM-AH and IM-RC,DMH-AH had the highest Ru~0content,and its moderate oxidation ability could avoid excessive oxidation of NH₃ into nitrate or nitrite in the catalytic process.The results of catalyst stability showed that DMH-AH had better recycling performance than IM-AH and IM-RC.In the research process of PMS activation to degrade M-cresol with Fe and N co-doped ordered mesoporous carbon materials,both Fe and N doping have a certain impact on the catalytic performance:too high or too low Fe doping is not conducive to the catalytic oxidative degradation of m-cresol,of which 5Fe-50 has the most appropriate Fe doping,which has the best catalytic oxidative degradation performance of M-cresol,and the degradation rate of M-cresol is 100%within 30 minutes.This is mainly due to the lack of active sites when the Fe doping amount is low,which makes PMS unable to be activated efficiently,while the higher Fe doping amount leads to the aggregation of Fe nanoparticles,thus reducing the utilization efficiency of metal active sites;N doping helps to promote the activation of PMS,and with the increasing N doping,the degradation rate of m-cresol increases.In addition,the results of the study on the catalytic performance affecting factors showed that the PMS concentration of 5mm and the initial p H of 6.8 were the most suitable conditions for the degradation of M-cresol(200 mg·L^-1);quenching experiment and EPR characterization test show that5Fe-50/PMS system degrades M-cresol by free radical path,in which SO₄^·-and·OH are the main reactive oxygen species,a small amount of O₂^·-in the system plays an auxiliary role in the degradation of M-cresol,and there is no ~1O₂ in this system.