Preparation Of Anatase By Metatitanic Acid And Its Effect On Ce-W/Ti Catalyst’s Denitration Performance

NOx from fuel combustion and automobile emissions has caused serious environmental pollution problems.At present,NH3-SCR technology is the mainstream technology for controlling NOx emissions,and it has the characteristics of high denitration efficiency,wide active temperature range,and low SO2 conversion rate.The core of NH3 selective catalytic reduction technology is the choice of catalyst,and the activity of the catalyst determines the level of NOx removal efficiency.It has been shown that the activity of SCR catalysts is affected by the carriers,active components and auxiliaries used.TiO2,Al2O3,and SiO2 are used as supports for denitration catalysts.Among them,TiO2 is widely used for Ce-based SCR catalyst support based on its good dispersibility and rich acid sites.Different TiO2 support structures lead to different catalyst activities.Therefore,this paper studies the effect of differrent TiO2 supports on Ce-W/Ti catalysts.The main work of this thesis is as follows:Preparation of different forms of TiO2 by adjusting H2TiO3 pyrolysis conditions;Ce-W/Ti catalysts with different support structures were prepared by co-precipitation method with 0.08WO3-0.35CeO2/TiO2 and evaluated its catalytic activity.On this basis,XRD,XPS,BET,H2-TPR,and NH3-TPD were used to study the effects of H2TiO3 pyrolysis conditions on the TiO2 phase,crystal form,specific surface area,and surface element valence distribution,and study on the effect of TiO2 on the catalytic activity of different supports.Conclusion as below:The effect of calcination temperature and time on the equivalent characteristics of TiO2 in H2TiO3 pyrolysis products shows that increasing roasting temperature and time,the crystal form of the product TiO2 tends to be complete,the R-TiO2 phase content increases,the average grain size becomes larger,the specific surface area and pore volume become smaller,the proportion of the surface adsorbed oxygen Oα content decreases,and the surface reduced reactive oxygen molecules.Therefore,the TiO2 has the highest specific surface area,the surface adsorbed oxygen Oα content,and the smallest grain size at the calcination temperature of200℃.And it will facilitate the denitration reaction.Investigate the effect of TiO2 support prepared at different calcination temperature and time on the denitration performance of Ce-W/Ti catalyst.The research results show that the Ce-W/TiO2 catalyst with TiO2 as the support of calcined H2TiO3 product at 200℃ for 1 hour shows good denitration performance.The temperature of the catalyst reaching 90%of the denitration efficiency reaches a minimum of 250℃ and the denitration temperature range reaches 250～500℃.As the temperature and time of roasting H2TiO3 increase,the temperature range of the Ce-W/TiO2 catalyst used as the carrier not only moves to the high temperature area,but also narrows,and the denitration performance decreases.The characterization results of the catalyst show that the specific surface area of the Ce-W/TiO2 catalyst with TiO2 as the carrier,which is calcined at 200℃ for 1 hour,and has a large specific surface area;the surface has a rich content of oxygen Oα,indicating that it has abundant oxygen vacancies.Ce in the catalyst is mainly CeO2 and Ce2O3,and the conversion of different valence states of Ce elements increase the concentration of oxygen vacancies,which is conducive to the improve-ment of the adsorption capacity of the catalyst.At low temperatures relatively,the area of H2 reduction peaks is large and there are abundant active reduction sites.The area of NH3 adsorption peaks is the largest,showing good adsorption capacity.