Low-Temperature Selective Catalytic Reduction DeNOX and Regeneration of Mn–Cu Catalyst Supported by Activated Coke

The activated coke is a promising support for catalysts, and it is important to study the performance of the activated coke catalyst on the removal of NOx. In the current research, a series of the activated coke-supported Mn–Cu catalysts are prepared by the incipient wetness impregnation method. The effects of the molar ration of Mn/Cu, the content of Mn–Cu, the calcination temperature, and reaction space velocity on NO conversion are investigated, and it was found that the 8 wt.% Mn0.7Cu0.3/AC had the best catalytic activity when the calcination temperature was 200 °C. The existence of SO2 caused the catalyst to deactivate, but the activity of the poisoning catalyst could be recovered by different regeneration methods. To uncover the underlying mechanism, BET, XPS, XRD, SEM and FTIR characterizations were performed. These results suggested that the specific surface area and total pore volume of the poisoning catalyst are recovered and the sulfite and sulfate on the surface of the poisoning catalysts are removed after water washing regeneration. More importantly, the water washing regeneration returns the value of Mn3+/Mn4+, Cu2+/Cu+, and Oα/Oβ, related to the activity, basically back to the level of the fresh catalyst. Thus, the effect of water washing regeneration is better than thermal regeneration. These results could provide some helpful information for the design and development of the SCR catalysts.

Preparation of Activated Coke by One-step Activation Method, Ammonization and K2CO3 Modification of Coal and Biomass

Coal and biomass are regularly used in the preparation of activated coke. In this paper, coal and biomass (poplar bark) were co-pyrolyzed, and activated coke was prepared by physical “one-step activation”, followed by ammonization and additional activation by potassium carbonate (K2CO3). The activation temperature was set at 800 °C, the time was 60 min, and the activation atmosphere contained 10% steam and 20% CO2 by volume in nitrogen. The physical and chemical properties of activated coke prepared by “one-step activation method” and “two-step activation method” were compared. The mole fraction of ammonia was 5%, 10%, 15%, 20% respectively and the concentration of K2CO3 solution was 3%, 6%, 9%, 12% respectively. It is found that the addition of ammonia can improve physical and chemical properties and adsorption capacity of activated coke, but the increase of ammonia mole fraction has little effect on the activation reaction. The physical and chemical structure of activated coke impregnated with 3% K2CO3 solution was found to be well developed. The surface of the produced activated coke prepared by the above activation methods has abundant microporous structure and organic functional groups, hence the final product is suitable to be used as adsorbent in practical applications.