Zhao Zhenzhen, Wang Liyin, Lin Xiangqing, Xue Gang, Hu Hui, Ma Haibin, Wang Ziyu, Su Xiaofang, Gao Yanan
School of Advanced Agricultural Science, Weifang University, Weifang 261061, China.
Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130, China.
Molecules. 2024 Aug 28;29(17):4079. doi: 10.3390/molecules29174079.
In view of the flue gas characteristics of cement kilns in China, the development of low-temperature denitrification catalysts with excellent anti-poisoning performance has important theoretical and practical significance. In this work, a series of MnCeO@TiO and tourmaline-containing MnCeO@TiO-T catalysts was prepared using a chemical pre-deposition method. It was found that the MnCeO@TiO-T2 catalyst (containing 2% tourmaline) exhibited the best low-temperature NH-selective catalytic reduction (NH-SCR) performance, yielding 100% NO conversion at 110 °C and above. When 100-300 ppm SO and 10 vol.% HO were introduced to the reaction, the NO conversion of the MnCeO@TiO-T2 catalyst was still higher than 90% at 170 °C, indicating good anti-poisoning performance. The addition of appropriate amounts of tourmaline can not only preferably expose the active {001} facets of TiO but also introduce the acidic SiO and AlO components and increase the content of Mn and O on the surface of the catalyst, all of which contribute to the enhancement of reaction activity of NH-SCR and anti-poisoning performance. However, excess amounts of tourmaline led to the formation of dense surface of catalysts that suppressed the exposure of catalytic active sites, giving rise to the decrease in catalytic activity and anti-poisoning capability. Through an in situ DRIFTS study, it was found that the addition of appropriate amounts of tourmaline increased the number of Brønsted acid sites on the catalyst surface, which suppressed the adsorption of SO and thus inhibited the deposition of NHHSO and (NH)HSO on the surface of the catalyst, thereby improving the NH-SCR performance and anti-poisoning ability of the catalyst.
针对我国水泥窑烟气特点，开发具有优异抗中毒性能的低温脱硝催化剂具有重要的理论和实际意义。本工作采用化学预沉积法制备了一系列MnCeO@TiO和含电气石的MnCeO@TiO-T催化剂。结果表明，MnCeO@TiO-T2催化剂（含2%电气石）表现出最佳的低温NH3选择性催化还原（NH3-SCR）性能，在110℃及以上时NO转化率达100%。当向反应中引入100 - 300 ppm SO2和10 vol.% H2O时，MnCeO@TiO-T2催化剂在170℃时的NO转化率仍高于90%，表明其具有良好的抗中毒性能。适量电气石的加入不仅能优先暴露TiO2的活性{001}面，还能引入酸性SiO2和Al2O3组分，并增加催化剂表面Mn和O的含量，这些均有助于提高NH3-SCR反应活性和抗中毒性能。然而，过量的电气石会导致催化剂表面形成致密结构，抑制催化活性位点的暴露，从而导致催化活性和抗中毒能力下降。通过原位漫反射红外傅里叶变换光谱（DRIFTS）研究发现，适量电气石的加入增加了催化剂表面布朗斯特酸位的数量，抑制了SO2的吸附，进而抑制了NH4HSO4和(NH4)2SO4在催化剂表面的沉积，从而提高了催化剂的NH3-SCR性能和抗中毒能力。
