半焦脱硝体系中重要碳氧中间体结构及其作用

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

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。

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.