华电技术 ›› 2020, Vol. 42 ›› Issue (10): 28-35.

• 污染物减排 • 上一篇    下一篇

半焦脱硝体系中重要碳氧中间体结构及其作用

  

  1. 1. 中国科学院 过程工程研究所,北京 100190;2. 中国科学院大学,北京 100049
  • 出版日期:2020-10-25

Structure and function of important C/O intermediates in semi‐coke DeNOx systems

  1. 1.Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China;2.University of Chinese Academy of Sciences,Beijing 100049,China
  • Published:2020-10-25

摘要: 采用产自国内 11 个地区的不同煤阶煤炭所制半焦进行烟气脱硝程序升温与恒温试验,发现 11 种样品可根
据脱硝效率明显分为 2 组。进一步通过 BET 孔结构分析,X 射线光电子能谱(XPS),透射电镜(TEM),X 射线荧光分
析(XRF)等手段对半焦进行表征发现:物理性质上,2 组半焦各具不同的吸附特性、微观片层结构特征以及孔径分
布特征;化学组分上,二者亦有明显不同的 C—O 单键含量、碱(土)金属含量,其中碱(土)金属含量相差 2~4 倍。试
验同时发现,这些组分含量又与 11 种半焦脱硝效率指标存在较明显而单一的线性相关关系(线性相关系度绝对值
|r|主要分布于 0.841~0.992)。结合前期计算机模拟与碱(土)金属改性对照实验初步推测:脱硝过程中,半焦表面形
成的 C—O 单键及其在反应体系中的化学行为可较合理地解释不同条件下半焦脱硝效果的差异性。

关键词: 半焦, 热解, 脱硝, 氮氧化物, 密度泛函理论, 碳氧中间体, 碳基脱硝

Abstract: Temperature programmed rising test(TPR)and constant temperature test for deNOx were conduct on semi ‐ coke
pyrolyzed from coals of different ranks from 11 regions in China.Based on their deNOx efficiencies,the 11 types of coke can
be divided into two groups.By means of BET pore analysis,X-Ray Photoelectron Spectroscopy(XPS),Transmission Electron
Microscope(TEM)and X-Ray Fluorescence(XRF),it is found that the two groups exhibit significantly different adsorption
isotherms, micro layered structure, and pore size distribution in terms of the physical characteristics; and chemically, the
amount of C—O single bond and alkaline earth metals(can be as great as 2~4 times of magnitude)varies differently in two
groups of samples.It is also found that their component has clear and simple linear correlation with denitration efficiency
indexes of the 11 types of coke (absolute value of linear correlation |r| sways within 0.841~0.992). Comprehensively
analyzing the simulation results and metal modification controlled tests,preliminary speculation was made that the
difference in semi‐coke's denitration effect under different conditions could be led by C—O single bond on its surface and
its chemical behavior in the reaction system during the denitration process.

Key words: semi‐coke, pyrolysis, DeNOx, NOx, DFT, C/O intermediate, denitration with carbon‐based catalysts