Preparation Of Self-Doping/Oxygen Vacancy Dependent Titanium-Based Catalyst And Its Performance In Selective Catalytic Reduction Of NO_x

The massive emission of nitrogen oxides?NO_x?in modern industry has great harm to the ecological environment and human health.The ammonia selective catalytic reduction?NH₃-SCR?denitration technology is currently one of the recognized high-efficiency denitration methods.The active window of the existing commercial SCR catalyst is in the middle and high temperature range and is narrow.How to improve the low temperature activity of the catalyst,widen the reaction temperature window,and obtain better economy and practicality are the hotspots in the field of SCR catalyst research.In this paper,Ti³⁺ion modified TiO₂ support is used,and the active ingredients V₂O₅ and CeO₂ are selected to be loaded on TiO₂.The reaction temperature window of the traditional V₂O₅/TiO₂ catalyst is widened,and it has excellent sulfur and water resistance.In order to study the changes of the physicochemical properties of the catalyst before and after modification,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,Raman spectroscopy?Raman?,specific surface area and pore structure analysis,and temperature-programmed tests were used respectively The technology?TPD/TPR?,electron paramagnetic resonance spectroscopy?EPR?and scanning electron microscope?SEM?and other chemical characterization methods made theoretical analysis.The research content is as follows:First,the Ti³⁺self-doped TiO₂ support was prepared by sol-gel method.The active component V of 1 wt.%was loaded with impregnation method,and the V₂O₅/TiO₂ denitration catalyst rich in oxygen vacancies was prepared.The results show that the activity efficiency of Ti³⁺self-doped V₂O₅/TiO₂ catalyst in the reaction temperature window is significantly higher than that of undoped vanadium titanium catalyst,and the active window in the low temperature range is effectively widened.The results show that the self doping of Ti³⁺can inhibit the formation of TiO₂ rutile phase and stabilize TiO₂ anatase crystal.The introduction of Ti³⁺resulted in a large number of oxygen vacancies,and the reaction with the oxygen adsorbed on the surface of TiO₂ resulted in the formation of superoxide radicals which promoted the rapid SCR reaction.At the same time,the surface acidity and redox ability of the catalyst are improved,which is helpful to improve the denitrification efficiency of NH₃-SCR reaction.Secondly,the Ti based denitration catalyst with two active components of Ce-V was prepared by impregnation and adding rare earth element Ce on the basis of Ti³⁺self-doped V₂O₅/TiO₂ catalyst.The results show that the introduction of Ce can effectively reduce the vanadium content and maintain high catalytic performance.When 6 wt.%Ce and 0.5 wt.%V are loaded,the overall activity of the catalyst is the best,and the activity efficiency can reach 90.4%at 180?,which further widens the activity temperature window of the catalyst.The results show that Ce doping can increase the adsorbed oxygen content on the surface of catalyst,regulate the coexistence of multivalent active components and further strengthen the interaction between active components and support,so as to effectively improve the performance of catalyst.In addition,on one hand,the influence of preparation conditions and reaction conditions on the performance of the catalyst was investigated,and the calcination temperature was optimized to achieve the optimal performance of the catalyst;on the other hand,the sulfur resistance and water resistance experiments showed that Ti³⁺self-doping and the introduction of Ce could improve the poisoning resistance of V₂O₅/TiO₂ catalyst.