摘要
活性焦是一种优良的孔隙结构材料,前人研究了活性焦在中高温条件下的脱硫脱硝性能,但鲜见其在低温(<100℃)条件下的脱硝性能研究。为了研究活性焦低温脱除NO特性,按照煤粉工业锅炉实际烟气组分配制模拟烟气,搭建固定床反应器试验台架,通过改变温度、氧浓度、SO_(2)浓度、水分等参数,研究工艺条件对活性焦脱除NO效率影响。采用红外光谱(FT-IR)、原位红外、热重试验(TG-DTA)、光电子能谱(XPS)、程序升温脱附(TPD)等手段表征反应前后活性焦的微观结构和表面化学性质。结果表明:50~90℃,温度越低,氧浓度越高,活性焦脱除NO效率越高。SO_(2)和水分的存在均不利于活性焦脱除NO。SO_(2)极性强,会与NO竞争吸附位及活性位点,水分则会在活性焦表面形成一层水膜,使活性焦毒化。活性焦低温脱除NO同时发生物理吸附和化学催化氧化作用,以物理吸附为主。物理吸附依赖于活性焦丰富的微孔结构和优良的比表面积。化学催化氧化依靠烟气中的游离氧气和活性焦表面的含氧官能团。NO开始脱附的温度为150℃,225℃时脱附浓度最高,600℃全部脱附。NO_(2)开始脱附温度为175℃,225℃时脱附浓度达到最高,500℃时全部脱附。
activated coke is an excellent pore structure material.The desulfurization and denitration performance of activated coke at medium and high temperature has been studied extensively by predecessors,but the denitration performance of activated coke at low temperature(<100℃)has been rarely studied.In order to study the characteristics of NO removal by activated coke at low temperature,simulated flue gas was prepared according to the actual flue gas group of pulverized coal industrial boiler,and the test bench of fixed-bed reactor was built.The influence of process conditions on NO removal efficiency of activated coke was studied by changing the parameters such as temperature,oxygen concentration,SO_(2) concentration and moisture.The microstructure and surface chemical properties of the activated coke before and after the reaction were characterized by FT-IR,in-situ IR,TG-DTA,photoelectron spectroscopy(XPS)and temperature-programmed desorption(TPD).The experimental results show that at 50-90℃,the lower the temperature is,the higher the oxygen concentration is,and the higher the NO removal efficiency of activated coke is.The presence of SO_(2) and water is not conducive to the removal of NO by activated coke.SO_(2) has strong polarity and will compete with NO for adsorptive sites and active sites.Water will form a layer of water film on the surface of activated coke,which makes the activated coke toxic.Physical adsorption and chemical catalytic oxidation take place simultaneously in the NO removal of activated coke at low temperature,and physical adsorption is the main process.Physical adsorption depends on the rich microporous structure and excellent specific surface area of activated coke.Chemical catalytic oxidation depends on free oxygen in flue gas and oxygen-containing functional groups on the surface of activated coke.The initial desorption temperature of NO is 150℃,the highest desorption concentration is observed at 225℃,and the desorption complete at 600℃.The initial desorption temperature of NO_(2) is 175℃,the desorption concentration reaches the highest at 225℃,and NO_(2) is completely desorbed at 500℃.
作者
张媛
陈隆
ZHANG Yuan;CHEN Long(China Coal Research Institute Company of Energy Conservation,Beijing 100013,China;State Key Laboratory of Coal Mining and Clean Utilization,Beijing 100013,China;National Energy Technology&Equipment Laboratory of Coal Utilization and Emission Control,Beijing 100013,China;China Coal Research Institute,Beijing 100013,China)
出处
《洁净煤技术》
CAS
北大核心
2021年第3期217-224,共8页
Clean Coal Technology
基金
煤科院节能技术有限公司科技发展基金技术创新项目(2020JNCX02-01)。
关键词
活性焦
低温
催化氧化
吸附
activated coke
low temperature
catalytic oxidation
adsorption
