活性炭循环脱硫再生对脱硝性能的影响机制

Effects of Activated Carbon Cyclic Desulfurization Regeneration on Denitrification Performance and Its Mechanism

为探究活性炭在多次循环过程中脱硫脱硝性能的变化规律和内在本质,将活性炭装填于固定床反应器进行10个周期的脱硫和再生循环,跟踪活性炭的脱硫脱硝性能,采用物理吸附仪、傅立叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)和拉曼光谱(Raman)等表征活性炭表面性质和孔道结构的变化,分析和阐释活性炭结构变化与脱硫脱硝性能之间的联系。结果表明:经过10次脱硫和再生循环后,活性炭的脱硫性能下降,选择性催化还原(SCR)活性由43%增加到72%;循环脱硫前后活性炭孔道结构和晶态结构变化不大;在脱硫再生过程中活性炭被原位酸化,表面生成了醌、酯、酸酐和羧基等官能团,这些表面官能团的增加不仅增强了氨气(NH_(3))的吸附能力,且有利于一氧化氮(NO)氧化为二氧化氮(NO_(2)),进而促进快速SCR反应的发生;活性炭的循环脱硫再生有利于活性炭脱硝性能的提高。

In order to explore the patterns and underlying mechanism of the variations in the desulfurization and denitrification performance of the activated carbon during multiple cycles,the activated carbon was filled in a fixed bed reactor and underwent 10 cycles of desulfurization and regeneration,and the desulfurization and denitrification performance of the activated carbon was recorded.The surface properties and pore structure changes in the activated carbon were characterized by using physical adsorption instrument,Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and Raman spectroscopy,and the relationship between the structure change in the activated carbon and the desulfurization and denitrification performance was analyzed and explained.The results show that the pore structure and crystal structure of the activated carbon are merely altered before and after the cyclic desulfurization.After 10 desulfurization and regeneration cycles,the desulfurization performance decreases,and the SCR activity increases from 43%to 72%.It is found that the activated carbon is acidified in situ during the desulfurization regeneration process,and functional groups such as quinone,ester,acid anhydride and carboxyl group are formed on the surface.The increase in these surface functional groups not only enhances the adsorption capacity of ammonia(NH_(3)),but also facilitates the oxidation of nitric oxide(NO)to nitrogen dioxide(NO_(2)),thereby promoting the rapid SCR reaction.In summary,the regeneration of the activated carbon is beneficial to the improvement of the denitrification performance of the activated carbon.