SO3 removal characteristics from flue gas of FCC regeneration process by activated carbon modified red mud adsorbent.

Sulfur trioxide (SO 3) is one of the major air pollutants in the flue gas of Fluid catalytic cracking (FCC) units during the regeneration process in refineries. However, it is difficult to remove SO 3 with the existing desulfurization systems. Nowadays, alkaline adsorbent spraying technology has been a promising method to remove SO 3. However, there is no relevant application research in the field of FCC regeneration flue gas. Therefore, in this paper, The SO 3 removal characteristics from FCC flue gas by activated carbon modified red mud adsorbent were studied, including modification method, reaction temperature and flue gas components. Combined with characterization analysis of adsorbents, the mechanism of SO 3 removal was studied. It was found that when the AC mass ratio is 10% and modification temperature is 400 ℃, the best LBRMAC adsorbent was achieved. When particle size is 0.096–0.125 mm and reaction temperature is 400 ℃, the highest SO 3 adsorption efficiency is up to 83.4%. The addition of NO has little influence on the adsorption efficiency of SO 3. The addition of SO 2 leads to competitive adsorption between SO 3 and SO 2 , resulting in a rapid decline in the removal efficiency of SO 3. Meanwhile, the characterization analysis proves that the SO 3 adsorption process mainly include chemical kinetics control stage and product layer diffusion stage. • Best modification of LBRMAC was achieved when the AC mass ratio is 10%. • Reaction temperature of 400 ℃ is optimal for SO 3 adsorption. • Particle size and SO 3 concentration have effects on SO 3 adsorption except NO. • There exists competitive adsorption between SO 2 and SO 3. • Chemical kinetics control stage and product layer diffusion stage mainly dominate SO 3 adsorption. [ABSTRACT FROM AUTHOR]