Beijing Tiandi Integration & Innovation TechnologyCorporation Ltd.

超低温催化脱硝是具有烟气成分简单、能耗低、阻力小等优点的新型脱硝工艺,而活性焦在超低温催化脱硝方面发挥重要作用,因而针对活性焦在不同气氛下的超低温催化脱硝及原位热再生实验研究,可为提升超低温催化脱硝性能提供技术支撑。利用微型固定床实验装置研究超低温(≤130℃)下不同气氛(氧化和还原)对活性焦脱除NO性能及热再生中NOx气体的影响规律与原位热再生机理。结果表明:活性焦在实验条件下脱除NO过程中,出口NO体积分数曲线随时间延长呈逐渐上升趋势,表明活性焦样品中的活性位不断被占据。其他条件不变,还原气氛下NO吸收量是氧化气氛的数倍,说明还原气氛更有利于活性焦对NO的脱除;温度越低,还原气氛与氧化气氛的NO脱除量差距越大,活性焦对NO的脱除性能越强。超低温氧化气氛下,活性焦对NO的脱除过程除存在吸附作用外,还存在催化氧化作用,可将NO氧化为NO2,并将NO2吸附于活性焦孔隙表面,吸附态NO2发生歧化反应,生成NO3。催化氧化脱硝后的活性焦在原位热再生过程中,氧化生成的高阶NOx受热又分解为NO。超低温氨气还原气氛下,除了发生NO催化氧化反应外,在还原剂NH3的作用下,活性焦表面还发生NO催化还原反应,推测有部分NO的氧化产物与NH3进一步反应生成硝酸铵,该3种反应是相互影响促进的关系。催化还原脱硝后的活性焦经原位热再生,催化氧化产物以NO形式释放,同时硝酸铵盐产物部分分解为N2和H2O。因此,还原气氛脱硝后热再生气中NO释放量与吸收量的比值比氧化气氛脱硝后的要小。随脱硝温度升高,数值随之增大,说明在实验条件下温度越高,催化还原占比越大。

Ultra low temperature catalytic denitrification is a new type of denitrification process with the advantages ofsimple flue gas composition, low energy consumption and low resistance. Activated coke plays an important role inultra⁃low temperature catalytic denitrification. Therefore, experimental research on ultra⁃low temperature catalyticdenitrification and in⁃situ thermal regeneration of activated coke under different atmospheres can provide technicalsupport for improving the performance of ultra⁃low temperature catalytic denitrification. Using a micro fixed bed exper⁃imental device, the influence of different atmospheres ( oxidation and reduction )at ultra⁃low temperature(≤130 ℃) on the NO removal performance of activated coke and the NOx gas in thermal regeneration, as well as thein⁃situ thermal regeneration mechanism, were studied. The results show that during the NO removal process of activa⁃ted coke under experimental conditions, the outlet NO concentration curve shows a gradual upward trend with time,indicating that the active sites in the activated coke sample are continuously occupied. Other conditions remain un⁃changed, and the absorption of NO in a reducing atmosphere is several times that of an oxidizing atmosphere, indica⁃ting that the reducing atmosphere is more conducive to the removal of NO by activated coke; the lower the tempera⁃ture, the greater the difference in NO removal between the reducing atmosphere and the oxidizing atmosphere, andthe stronger the NO removal performance of activated coke. Under ultra⁃low temperature oxidation atmosphere, theremoval process of NO by activated coke not only involves adsorption, but also catalytic oxidation, which can oxidizeNO to NO2 and adsorb NO2 on the pore surface of the activated coke. The adsorbed NO2 undergoes a disproportion⁃ation reaction, generating NO3. During the in⁃situ thermal regeneration process of the activated coke after catalyticoxidation and denitrification, the high⁃order NOx generated by oxidation is heated and decomposed into NO. Underthe ultra⁃low temperature ammonia reduction atmosphere, in addition to NO catalytic oxidation reaction, under theaction of reducing agent NH3, NO catalytic reduction reaction also occurs on the surface of the activated coke. It isspeculated that some NO oxidation products further react with NH3 to generate ammonium nitrate, and these three re⁃actions are mutually influencing and promoting. After catalytic reduction and denitrification, the activated coke un⁃dergoes in⁃situ thermal regeneration, and the catalytic oxidation product is released in the form of NO, while the am⁃monium nitrate product is partially decomposed into N2 and H2O. Therefore, the ratio of NO release to absorption inthe hot regeneration gas after denitrification in a reducing atmosphere is smaller than that after denitrification in an oxi⁃dizing atmosphere. As the denitrification temperature increases, the numerical value increases, indicating that underexperimental conditions, the higher the temperature, the greater the proportion of catalytic reduction.

天地科技股份有限公司科技创新创业资金专项重点资助项目(2021-TD-ZD005)

杨石, 王乃继, 王实朴, 等. 活性焦超低温催化脱硝及原位热再生实验研究 [J]. 煤质技术, 2023, 38(5): 16-21.

YANGShi, WANG Naiji, WANG Shipu, et al. Experimental study on ultra⁃low temperature catalytic denitrifica⁃tion and in⁃situ thermal regeneration of activated coke under different atmospheres [J]. Coal Quality Technology,2023, 38 (5): 16-21.