低温NH3-SCR是排烟温度低的非电力行业烟气脱硝的重要技术选择,低成本、结构可调性好的碳材料是最具潜力的低温NH3-SCR催化剂之一,但面临脱硝效率低的瓶颈。本文以低成本、大储量准东煤为原料,基于一步催化活化工艺制备了具有典型孔隙配组与含氮官能团的活性焦催化剂,探究了活性焦孔隙配组与表面官能团对不同烟气条件下低温NH3-SCR的影响。研究结果表明分级孔与含氮官能团对NH3-SCR均有显著促进作用,兼具分级孔与含氮官能团的氮掺杂分级孔活性焦由于同时改善了传质通道与反应动力学,具有最优的NH3-SCR性能,160℃条件下的脱硝效率高达83.5%,相比氮掺杂微孔活性焦、无掺杂分级孔焦和微孔活性焦分别提升了14.0%、26.5%和110.9%;在SO2或H2O存在条件下,分级孔和含氮官能团对NH3-SCR性能的提升作用更加明显,微孔活性焦脱硝效率会由39.6%衰减至13.8%和34.9%,而氮掺杂分级孔焦脱硝效率有所提升,达86.4%和86.7%,这可能与官能化分级孔环境强化不同烟气组分间的协同效应有关。探明了碳基低温NH3-SCR性能与碳材料理化结构之间的依存关系,为发展高性能碳基低温NH3-SCR技术提供了新思路。

Low-temperature NH3-SCR is an important technology choice for flue gas denitrification in non-electricity industries with lowexhaust temperature, and low - cost carbon materials with good structural tunability are one of the most promising low - temperatureNH3-SCR catalysts, but face the bottleneck of low denitrification efficiency. In this paper, based on a one-step catalytic activationprocess, activated coke catalysts with typical pore configurations and nitrogen-containing functional groups were prepared from low-costand large-volume Jundong coal as raw materials, and the effects of activated coke pore configurations and surface functional groups on thelow- temperature NH3 - SCR under different flue gas conditions were investigated. The results showed that both graded pores andnitrogen-containing functional groups have significant effects on NH3 -SCR, and the nitrogen-doped graded-porous activated coke withboth graded pores and nitrogen-containing functional groups has the optimal performance of NH3-SCR due to the simultaneous improvement of the mass transfer channels and reaction kinetics, and its denitrification efficiency reaches as high as 83.5% under the condition of160 ℃ . The enhancement effects of graded pores and nitrogen-containing functional groups on the NH3-SCR performance are more obvious in the presence of SO2 or H2 O, and the denitrification efficiency of microporous activated coke decays from 39.6% to 13.8% and34.9%, whereas the denitrification efficiency of nitrogen - doped graded - porous coke improves to 86. 4% and 86. 7%, respectively.This may be related to the synergistic effect between different flue gas components enhanced by the functionalized graded pore environment.In this study, the dependence between the performance of carbon-based low-temperature NH3 -SCR and the physicochemical structure ofthe carbon materials was investigated, which provides a new idea for the development of high-performance carbon-based low-temperatureNH3-SCR technology.

0 引言

1 试验

   1.1 材料制备

   1.2 样品表征

2 结果与讨论

   2.1 活性焦理化性质表征

   2.2 分级孔与含氮基团对NOx还原特性的耦合影响

   2.3 SO2对活性焦低温NOx还原特性的影响

   2.4 H2O对活性焦低温NOx还原特性的影响

3 结论