蜂窝状SCR脱硝催化剂成型配方选择

通过对钒钛基蜂窝状SCR脱硝催化剂的制备工艺研究,探索了二氧化钛(TiO2)载体及成型剂配方对产品机械性能及脱硝活性的影响.分别选用工业级硫酸法锐钛型TiO2和进口商业纳米锐钛型TiO2为载体原料,所考察的主成型剂包括二氧化硅(SiO2),活性氧化铝(γ-Al2O3),以及SiO2和硼酸(H3BO3)的混合粉体.进一步对载体及所制备催化剂样品进行表征,机械强度及脱硝活性测试.结果表明,商业纳米级TiO2较工业级TiO2在杂质含量、粉体粒径、分散度等方面占有明显优势,但TiO2晶粒尺寸要高于后者,比表面积亦低于工业级样品.在SCR催化剂制备上,相对工业级TiO2而言商业纳米级TiO2制备样获得了较高的机械强度,但其在脱硝活性方面并不占有优势.而对主成型剂配方的探索显示,以SiO2与H3BO3按一定比例混合得到的成型剂配方不但能够显著提高蜂窝状催化剂的机械性能,另一方面也能够维持其较高的脱硝活性,因此该配方作为钒钛基SCR催化剂的成型剂是合理可行的.

Select of molding formulations of honeycomb SCR DeNOx catalysts

The honeycomb V/Ti-based SCR DeNOx catalysts were prepared and the influences on mechanical strength and denitration performance of catalyst samples from TiO2 carrier and forming agent were studied respectively. Two types of TiO2 were employed as the carrier material which included the industrial grade sulphate process anatase TiO2 and commercial anatase nano-TiO2. And three types of forming agent were selected for honeycomb catalysts preparation which included SiO2, γ-Al2O3, the mixed powders of SiO2and H3BO3. The characterization, mechanical strength and denitration performance of the carrier/catalyst samples were tested. The results showed that the commercial nano-TiO2had advantages in particle diameter, dispersion characteristic and impurity contents relative to industrial grade TiO2, but it had smaller specific surface area because of bigger grain size. Also the honeycomb samples prepared from commercial nano-TiO2presented relatively lower denitration activity compared to those from industrial grade TiO2, but had excellent mechanical strength. On the other hand, it could be concluded from the research of forming agents that the molding formulations of mixed powders of SiO2and H3BO3for honeycomb SCR catalysts preparation not only brought significant enhancement on the mechanical property, but also maintained the idea activity of catalysts, which indicated the process of honeycomb V/Ti-based SCR DeNOx catalyst prepared with mixed powders of SiO2and H3BO3as forming agent was reasonable and feasible.