Preparation Of Catalysts Based On Refining Wastes And Evaluation Of Their Performance In Conjunction With Ozone Treatment Of Wastewater

The increasing proportion of heavy oil in the refining and chemical raw materials,causes the increasing organic load,especially the load of refractory organic chemicals(ROCs),increasing biological toxicity,decreasing biodegradability as well as the increase of biochemical degradation difficulty of the refining and chemical wastewater.During the stepwise treatment,refractory organic chemicalsare accumulated leadingto excessive organic loads.Under the pressure of"discharge standard"and"water quality deterioration",the refining and chemical industry urgently needs efficient and low-cost wastewater treatment technology.Due to the low-costing,simple operation and strong mineralization capacity,catalytic ozonation has become the leading technology in the standard treatment of refining and chemical wastewater.The catalyst is related to the treatment effect and operation cost and is the decisive factor for the implementation of the project.The cost of wastewater labeling is still high,and additional waste is added when the catalyst is deactivated.If high activity ozone catalysts can be prepared from carbon-based/aluminum-based wastes,spent bleaching earth and surplus activated sludge,not only can the cost of wastewater treatment be reduced,and additional waste can be avoided.It will effectively promote the full implementation of the wastewater standard raising project in the refining and chemical industry and fully meet the increasingly stringent pollution emission reduction requirements.In this paper,the recycling process of refining chemical excess activated sludge and spent bleaching earth was unified with the preparation process of ozone catalyst.During the catalytic pyrolysis of carbon-based/aluminum-based waste to produce oil and gas,the preparation of composite metal-supported carbon-based or carbon-aluminum composite ozone catalyst was realized simultaneously.Realizing the resource recovery of all components of the refining and chemical waste and the low-cost treatment of the refining and chemical waste,can help the overall solution of the two major problems of"waste disposal"and"waste water discharge bid"in the refining and chemical industry.The main results obtained in the research process are as follows:(1)In this chapter,solid waste clay from the refinery was used as raw material to prepare catalysts SBE-N2-650,SBE-O2-650,SBE-N2-850 and SBE-O2-850 for ozone-catalyzed oxidation.At the same time,pyrolysis oil and pyrolysis gas were recovered to further explore the efficiency and reaction mechanism of catalyst SBE-N2-650.The results showed that four catalysts(SBE-N2-650,SBE-O2-650,SBE-N2-850 and SBE-O2-850)were prepared by heating SBE at 650℃and 850℃,respectively.Compared with SBE-N2-850 and SBE-O2-850,SBE-N2-650 and SBE-O2-650 have higher specific surface area and richer surface O-H sites.The presence of O-H active site on the surface promoted its high catalytic activity.The additional carbon was found only in SBE-N2-650 and SBE-N2-850,while no carbon was found in SBE-O2-650 and SBE-O2-850.The addition of carbon element has a positive effect on the improvement of catalytic activity.Among all the catalysts prepared,the activity of SBE-N2-650 was the highest.Compared with ozonation alone,SBE-N2-650 co-COP can increase the rate of benzoic acid mineralization by 36%.Molecule O3 was decomposed at the active site on the surface of catalyst SBE-N2-650,producing hydroxyl radical·OH,and a certain amount of superoxide radical(·O2~-)or singlet oxygen(~1O2).In addition to develop a useful catalytic material,this research has produced gas and liquid products with high calorific values that can be used to produce energy.In this study,the potential of SBE in the treatment of refractory pollutants in catalytic ozonation was introduced.(2)In this chapter,SBCp was prepared by treating the remaining activated sludge from refining and refining by traditional pyrolysis method;Further alkaline washing resulted in SBCm.SBCp and SBCm contain a variety of carbon containing functional groups,metal oxides(Al,Ca,Fe,Mg and Zn)and non-metallic oxides(Si O2).Compared with SBCm,SBCp is more abundant in surface functional groups,and the specific surface area and pore volume of the former are lower than that of the latter.SBCp is dominated by microporous structure,while SBCm is dominated by mesoporous structure.In the reaction system of nitrobenzene solution catalyzed by ozone oxidation at different initial p H(p H=5.8,7.0 and 10),the presence of SBCp and SBCm significantly improved the removal rate of nitrobenzene.At the initial p H of 5.8 for 45 min,the TOC removal rate of nitrobenzene oxide solution catalyzed by SBCp and SBCm was higher than that of ozone alone by 41.6%and 33.9%,respectively.At different initial p H conditions,the TOC removal rate of SBCp and SBCm was higher than that of SAC.The TOC removal rate of real wastewater was also significantly higher than that of ozone oxidation alone.The catalytic oxidation of SBCp and SBCm follows the mechanism of free radical oxidation.The surface metal oxides and carbonaceous functional groups stimulate ozone and accelerate the decomposition to produce free radicals.The evaluation results showed the potential advantages of SBC catalyst in the treatment of refractory organic wastewater by ozone catalytic oxidation.(3)A new metal-catalyzed sludge pyrolysis system was developed in this chapter,which can improve the efficiency of sludge pyrolysis.The types of metals,the loading capacity of metals and the rate of pyrolysis temperature all affect the oil and gas production rate of sludge pyrolysis.The optimal content of metal component in sludge pyrolysis was 0.9wt%Mn,and the optimal pyrolysis condition was that the temperature rises to 850℃at 30℃/min at a temperature rise rate of 1 h.The solid products were further treated after the oil and gas products were collected here.Alkaline washed Mn catalyzed sludge catalyst,can be in the ozone catalytic oxidation treatment of organic sewage,achieving very excellent results,can produce·OH free radicals efficiently and permanently.Compared with SOP system,the TOC removal rate of nitrobenzene doubles by alkaline washing Mn catalyzed sludge catalyst.In this study,the great potential of simultaneous preparation of ozone catalyst by Mn metal catalytic sludge pyrolysis in deep treatment of organic wastewater was illustrated.