烧结烟气中CO和NOx排放是当前大气污染治理的重点,但传统的NH3-SCR技术存在与烟气温度不匹配、CO处理方式不经济、氨逃逸严重等问题。为了探究CO协助NH3-SCR脱硝技术的规律,利用共沉淀法开发了一种以CoMnCe为活性成分的脱硝催化剂,可利用烧结烟气中的CO协同NH3脱除NOx,既可提高烟气中CO利用方式,又可降低NH3使用量。活性测试结果表明Ce物质的量比为0.75时,其催化剂具有最佳协同脱硝效率,125℃下NO转化效率高达98%;XRD、Raman、XPS、TEM、H2-TPR等表征结果表明催化剂中Ce物质的量比的增加抑制了Co3O4中晶粒的生长,尽管Co3O4和CeO2仍保持原有晶格结构,但仍有部分Co或Mn原子与Ce原子相互掺杂,导致金属晶格畸变,催化剂表面形成缺陷结构,并生成大量氧空位,同时Ce物质的量比较大时,导致CeO2覆盖催化剂表面结构,且过剩的CeO2在催化剂表面出现团聚现象,阻碍Mn和Co物种参与催化反应;催化活性测试发现制备的催化剂表现出一定抗氧抑制能力,特别是Ce物质的量比较低时,低温下CO-SCR反应活性较好,而随Ce物质的量比增加,催化剂抗氧抑制能力下降;同时随温度升高,表面氧在催化剂表面流动加快,从而促进反应进行,此时含Ce较多CMC2催化剂表现出最佳的抗氧抑制性能,CO降低了NH3-SCR脱硝活性,但对于CMC0.75催化剂,在相对较低温度下,其协同脱硝效率仍较高,这可能是由于催化剂含有的Co、Mn和Ce金属氧化物具有极高的氧化能力,因此合理控制不同金属间的比例与分布,可提高催化剂表面氧化能力,增强表面氧流动,增强协同催化活性。

The emission of CO and NOx in sintering flue gas is the focus of current air pollution control. However, the traditional NH3-SCRtechnology has problems such as unmatched flue gas temperature, uneconomical CO treatment, and serious ammonia slip. In order to explore the law of CO assisted NH3-SCR denitrification technology, a series of de-NOx catalysts with CoMnCe as the active component weredeveloped by coprecipitation method. CO in the sintering flue gas can be used to synergize NH3 to remove NOx, which can improve the utilization of CO in the flue gas and reduce the use of NH3. The performance test results show that when Ce molar ratio is 0.75, the catalystexhibits the best synergistic NOx removal efficiency, and the NO conversion efficiency is up to 98% at 125 ℃ . The characterization resultsof XRD, Raman, XPS, TEM, H2-TPR, etc. indicate that the increase of Ce molar ratio in the catalyst inhibits the growth of the grains inCo3O4. Although Co3O4 and CeO2 still maintain the original lattice structure, there are still some Co or Mn atoms doped with Ce atoms,resulting in the distortion of the metal lattice, the formation of defect structures on the catalyst surface, and the generation of a large number of oxygen vacancies. At the same time, when the Ce molar ratio is relatively large, the catalyst surface structure is blocked byCeO2. Moreover, the excess CeO2 agglomerates on the catalyst surface,preventing Mn and Co species from participating in the catalytic reaction. The catalytic activity test finds that the prepared catalyst shows a certain anti oxygen inhibition ability, especially when the mole ratio of Ce is relatively low, the CO-SCR reaction activity is better at low temperature, and the anti-oxygen inhibition ability of the catalystdecreases with the increase of the mole ratio of Ce. At the same time, with the increase of temperature, the surface oxygen flows faster onthe catalyst surface, thus promoting the reaction. At this time, the CMC2 catalyst with more Ce shows the best anti oxygen inhibition performance, and the NH3 - SCR denitrification activity is reduced by CO. However, its synergistic denitrification efficiency for theCMC0.75 catalystis still high at relatively low temperature, which may be due to the high oxidation capacity of the Co, Mn and Ce metaloxides contained in the catalyst, Therefore, reasonable control of the proportion and distribution of different metals can improve the oxidation capacity of the catalyst surface, enhance the flow of surface oxygen and the synergistic catalytic activity.

山东省自然科学基金资助项目(ZR2021QE066);齐鲁工业大学人才资助项目(2023RCKY162)

张兴宇,刘倩倩,糜淑琪,等.Ce 对 CoMnOx催化剂协同 CO/ NH3脱硝性能[J].洁净煤技术,2023,29(12):34-41.

ZHANG Xingyu,LIU Qianqian,MI Shuqi,et al.Effect of Ce on the NOx removal performance of CoMnOx catalysts synergistic CO/ NH3[J].Clean Coal Technology,2023,29(12):34-41.