Improved Nitrogen Oxide Removal from Simulated Flue Gas by Modified Peanut Shell Chars Through Acid Pickling and Nitrogen Doping

Peanut shell char with high alkali metal and ash content was used in this study to remove nitrogen oxide (NO) from simulated flue gases. Effects of acid pickling and nitrogen doping of the biochar (BC) materials on the removal selectivity were investigated in a fixed bed reactor. Results show that CaO, MgO, SiO2, AgO2, CuO, and so on contained in the ash of peanut shell are not conducive to the pore development of biochar and grafting of nitrogen-containing functional groups during the nitrogen doping process. Ash pickling improves the development of pore structure, and decreases the ratios of H/C, O/C, and (O+H)/C. The NO ratio and reaction selectivity of biochar follow the order as pickling treatment (BC-A) > raw peanut shell char (BC) > nitrogen doping treatment (BC-N). Through a combined effect of ash pickling and nitrogen doping, BC-A-N has the highest NO removal ratio and reaction selectivity because of the improved pore characteristics and introduction of nitrogen-containing functional groups.