李婷,潘冠福
LI Ting,PAN Guanfu

• 1:煤科院节能技术有限公司

摘要(Abstract)：

活性焦是一种高性价比的炭基催化脱硝材料,为研究其在低温无氨条件下的脱硝性能及热再生情况,采用固定床试验装置,进行低温脱除NO性能评价及原位热再生试验;并对2种试验用活性焦的比表面积、孔径分布和表面官能团等进行表征分析,研究表面特性对去除NO性能的影响;初步探讨活性焦对NO的低温脱除及热再生机理。结果表明:在进口NO体积浓度100×10-6、O_2体积浓度6%、反应温度70℃、空速1 000 h-1的NO脱除试验条件下,出口NO浓度随时间增加逐渐上升,脱硝率则直线下降。结合红外表征,定性说明活性焦脱除NO过程中存在催化氧化及吸附,可能的机理是活性焦中活性官能团将NO氧化为NO_2,并以吸附态NO_2形式赋存于活性焦孔隙表面,部分化学吸附态NO_2又在活性焦表面发生歧化反应,形成吸附态NO_3。O_2体积浓度6%、再生温度70～400℃、升温速率2℃/min的热再生试验条件下,NO浓度先快速上升,100～150℃达到平台,210℃左右达到脱附量峰值,此时NO脱附折算浓度约85 mg/m3,之后NO浓度逐渐下降至0;模拟烟气在250℃以上时,CO开始析出,CO生成量与再生温度成正比。脱硝后的活性焦在原位热再生过程中,吸附态NO_2又分解为NO释放出来。2种试验用活性焦样品的微观孔隙结构较为相似,活性焦样AC1和AC2的等温曲线都属于IV型等温曲线,迟滞回线属H4型,这说明2种样品的微观结构多为狭缝状孔道;AC2在吸附脱附曲线低P/P0区拐点处的吸附量、孔容、BET比表面积比AC1略大,说明前者样品中的微孔相对更多;活性焦样AC1和AC2的最可几孔径分别为1.76和1.57 nm。XPS和脱硝性能评价发现含有更多含氧/氮官能团的活性焦样品,脱硝活性更强。
Active coke is a kind of carbon based catalytic denitrification material with high cost performance.In order to study its denitrification performance and thermal regeneration under the condition of low temperature and no NH3,the fixed bed experimental device was used to evaluate the performance of NO removal at low temperature and in-situ thermal regeneration experiment.The specific surface area,pore size distribution and surface functional groups of the two experimental active coke were characterized and analyzed to study the influence of surface characteristics on the NO removal performance.The effect of active coke on NO removal at low temperature and the mechanism of thermal regeneration were preliminarily discussed.The results show that under the experimental conditions of NO removal with the inlet volume concentration of NO 100 × 10-6,the volume concentration of O_26%,the reaction temperature 70 ℃ and the space velocity1 000 h-1,the outlet NO concentration increases gradually with time,and the denitrification rate decreases linearly.Combined with the infrared characterization,it is qualitatively indicated that there is catalytic oxidation and adsorption in the process of NO removal from the active coke.The possible mechanism is that the active functional group in the active coke oxidizes NO to NO_2,which occurs on the pore surface of the active coke in the form of adsorbed NO_2,and some of the chemically adsorbed NO_2 reacts with disproportionation on the surface of the active coke,forming adsorbed NO_3.Under the thermal regeneration test conditions of 6% O_2,70-400 ℃ regeneration temperature and 2 ℃/min heating rate,the NO concentration first increases rapidly,reaches the platform at 100-150 ℃,and reaches the peak value of desorption capacity at 210 ℃ .At this time,the conversion concentration of NO desorption is about 85 mg/m3,and then the NO concentration gradually decreases to zero.When the simulated flue gas is above 250 ℃,CO begins to separate out,and the amount of CO generated is directly proportional to the regeneration temperature.In the process of in-situ thermal regeneration of the activated coke after denitration,the adsorbed NO_2 is decomposed into NO and released.The microstructure of the two kinds of activated coke samples is similar.The isothermal curves of AC1 and AC2 belong to IV type isothermal curves,and the hysteresis loop belongs to H4 type,which shows that the microstructure of the two kinds of samples is mostly slit like pores.The adsorption capacity at the inflection point of the low P/P0 area of the adsorption desorption curve,pore volume and BET specific surface area of AC2 are slightly larger than those of AC1,indicating that there are more micropores in the former sample.The pore size of AC1 and AC2 are 1.76 and 1.57 nm,respectively.The results of XPS and denitrification performance evaluation of the two samples show that the denitrification activity of the active coke samples containing more oxygen/nitrogen functional groups is stronger.

关键词(KeyWords)： 活性焦;低温催化氧化脱硝;NO脱除;热再生
active coke;low temperature catalytic oxidation denitration;NO removal;thermal regeneration

Abstract:

Keywords:

基金项目(Foundation): 中国煤炭科工集团有限公司科技创新创业资金专项面上资助项目(2018MS003);; 天地科技股份有限公司科技创新创业资金专项项目(2019-TD-MS012)

作者(Author): 李婷,潘冠福
LI Ting,PAN Guanfu

DOI: 10.13226/j.issn.1006-6772.20042401

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