Basic Research And Preparation Of Mixed Oxide DeNOx Catalyst

At present, SCR is the most mature one in a variety of flue gas denitrificationtechnologies both at home and abroad. But compared with other countries, thistechnology began later in our country, especially we have no proprietary intellectualproperty rights on the preparation of the catalyst as the core technology, so to use SCRtechnology more mature, we must be independent research SCR denitration catalyst.The catalyst as the core of SCR technology, in our country has a broad market demand,and its investment in SCR denitration system account for a third, while the price of thecurrent commercial catalyst is higher. Therefore, this topic chosed a mixed oxide（Hereinafter referred to as M） of low price as the main raw material for the preparationresearch of NH₃-SCR denitration catalyst, that is on the basis of M surface propertiesanalysis and research, inspected the effect of binder for the mixed oxide formingperformance, lay the foundation of realizing the mixed oxide denitration catalystmolding.Based on characterization means such as XRF, XRD, metallographic microscope,physical and chemical properties of mixed oxide was studied, and in combination withcompressive strength, BET specific surface area, NH₃-TPD inspected the effect oforganic binders （PVA, MC, PAM）, inorganic binders （Al₂O₃, bentonite） and organic-inorganic mixed binders for the mixed oxide forming performance.The results showed that the original mixed oxide specific surface area is small, just1.485m²/g, it is not conducive to load active ingredien，we need to consider the effectsof the specific surface area on catalyst activity in a follow-up study. Composite all theexperimental data, we selected the conditions of multiple metal oxide in the subsequentexperiments: dry ball mill45min （1800r/min）, screening the multiple metal oxidewhich is greater than80mesh as the main raw material. By the process of each bindermolding mixed oxide, we know organic binder to mixed oxide forming, paste fluidity isgood, the pelleting machine tabletting, pelletizing process is easier to implement,thereinto MC is the best one, when choosing mixed binder for mixed oxide forming,organic binder forming characteristics also occupy the dominant role. The compressivestrength of mixed oxide molding only with organic binder is not high, while the mixedoxide molding with inorganic binder had a better compressive strength, the highestcompressive strength of bentonite is1.846MPa, compared with separate using of organic binder, inorganic binder addition can significantly improve compressivestrength of the catalyst. When using organic binder to mixed oxide forming, the moldingoxide BET specific surface area related to the molecular weight of adhesive, molecularweight is larger, a large number of pores will form while gas formation in the process ofroasting, this can cause its collapse of the pore structure, and leading to moldingmaterial specific surface area decreased. When choosing inorganic binder forming, thereis a bigger specific surface area, compared with only using organic binder forming, BETspecific surface area of forming oxide get from mixed binder forming has increasedsignificantly. Through specific surface area compared with compressive strength of eachbinder to mixed oxide molding of optimal compressive strength molding material, weknow there is no obvious positive correlation between compressive strength and specificsurface area. The ammonia adsorption properties of molding material with each binderto mixed oxide are similar, NH₃adsorption capacity and surface acid amount is modest,there is no obvious positive correlation between NH₃adsorption capacity, surface acidamount and the compressive strength of the molding oxide.