Preparation Of Carrier Of Flue Gas Desulfurizer From Activated Coal Fly Ash

Coal fly ash has become one of the largest solid wastes in China. Such a large number of waste solids not only occupy large amounts of land, but also cause serious ecological disasters. Thus, development of new ways to advance its resource utilization rate is the fundamental way to solve the dump and contamination of coal fly ash.SO2as a kind of atmosphere pollutant emitted from coal burning has caused serious environmental problems. Coal fly ash with large porosity and specific surface areas was often used as sorbents. It contains many amounts of useful elements such as aluminum, silicon and iron which are usually used as the carrier or active components of the catalysts. So, coal fly ash being used as the carrier of the desulfurization agent of flue gas is significance to environmental, social and economic.Coal fly ash is mainly composed of mullite and other high degree of polymerization of inert vitreous and its reactivity is very poor. So, the activation of fly ash is very important necessary to its resources utilization. The paper uses calcination under high temperatures to activated coal fly ash and investigated the effect of the addition of NaOH and Na2CO3additives on activation effectives. The methods including scanning electron microscopy (SEM), thermo gravimetric-differential thermal (TG-DSC) and X-ray diffraction (XRD) were used to characterize the changes of appearance and phases. The best activation methods and conditions of coal fly ash were found out and the activation mechanisms were also analyzed.After activation, the aluminum, silicon and other elements of fly ash can be used directly. Two kinds of methods including acid and basic method were used to prepare the active carrier. The catalysts were prepared after the active components were loaded on the carriers and the evaluations of desulfurization activity were carried through. Several better catalyst carriers were screened out. Finally, a kind of optimum preparation technology of the desulfurization carrier was obtained. The conclusions were as following:(1) The whole activation process of coal fly ash essentially was the depolymerization process of the high degree of polymerization matters. At the lower temperatures (<600℃), the depolymerization effects of the polymerization matters were improved mainly by NaOH. At the higher temperatures (>600℃), however, Na2CO3play a major role. Under the action of the mixture additives containing NaOH and Na2CO3, the dissolution rate of alumina increased fiercely with the calcination temperatures increasing from400℃to700℃and the value could reach95%or so at700℃.(2) Alumina was extracted from the activated fly ash by HC1or NaOH. γ-Al2O3was prepared using NaOH or NH3·H2O as precipitant by controlling pH. Based on these, the complicated Al-Si carrier containing Y-A12O3were prepared.(3) Coal fly ash as raw material was changed into the cordierite based material. γ-Al2O3/cordierite complicated carrier was prepared by coating γ-A12O3on the cordierite based material. CuO/γ-Al2O3cordierite catalyst showed the better the desulfurization activity and the sulfur capacity SC80achieved0.35g S/10g. So, a kind of optimum preparation technology of desulfurizer carrier was formed.