RESUMEN
In this study, nitrogen-doped modified activated carbons were synthesized for H2S removal from Zhuxi activated carbon and 4,4'-bipyridine as raw material and nitrogen source, respectively. The synthesis strategy was hydrothermal treatment and subsequent NH3 annealing, and the formation and conversion patterns of the different N configurations were investigated. When the annealing temperatures were 500 °C and 600 °C, N-5 account for the majority. As the annealing temperature increased, the proportion of N-6 gradually increased. After the temperature increased to 1000 °C, N-5 and N-6 were converted to N-Q to a certain degree, while the amount of nitrogen doping decreased significantly. The sample H160-0.2-800 exhibited excellent H2S removal with a high sulfur capacity of up to 206.89 mg/g, significantly higher than that of the original activated carbon ZX1200 (67.56 mg/g). The reason for this is that the micropores (Vmic = 0.5155 cm3/g) and specific surface area (SBET = 1369.5 m2/g) of the modified activated carbon are more developed than those of the original activated carbon. A high nitrogen content (3.14 wt%) and N-6 configuration proportion (73.56 %) are significant reasons for the excellent adsorption properties. The mechanism of the catalytic oxidation was investigated. The introduction of surface nitrogen-containing functional groups alkalizes the activated carbon surface, enhancing the adsorption and dissociation of H2S and O2 and facilitating the formation of sulfur radicals and elemental sulfur.
RESUMEN
As treatments for mainstream pollutants in coal-fired power plants have been established, the control of non-conventional pollutants, such as SO3 and HCl, is gradually gaining attention. In this study, combined SO3 and HCl removal is proposed based on SO3 removal by absorber injection. However, it is challenging to selectively absorb SO3 and HCl from SO2-rich atmospheres. Therefore, Ca(OH)2 was modified via ball milling and doping with CuO for the combined removal of SO3 and HCl. The results showed that ball milling reduced the particle and grain sizes of Ca(OH)2, which increased the active sites of Ca(OH)2 and prolonged reaction time. After modification by ball milling, SO3 absorption per mg of Ca(OH)2 increased by 40 %. However, HCl removal efficiency was difficult to improve by modifying Ca(OH)2 using only ball milling under SO3 and SO2 atmospheres. Therefore, the dechlorination capacity of Ca(OH)2 was improved by adding ions during the ball milling process. Doping of Ca(OH)2 with Cu2+ changed its crystal structure, weakened the diffusion resistance of HCl, and improved Ca(OH)2 utilization. Additionally, it increased the energy of Ca(OH)2 to adsorb HCl.
