Szymaszek-Wawryca Agnieszka, Díaz Urbano, Samojeden Bogdan, Motak Monika
Faculty of Energy and Fuels, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Kraków, Poland.
Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicais, Avd. de los Naranjos s/n, 46022 Valencia, Spain.
Molecules. 2022 May 6;27(9):2983. doi: 10.3390/molecules27092983.
The application of layered zeolites of MWW topology in environmental catalysis has attracted growing attention in recent years; however, only a few studies have explored their performance in selective catalytic reduction with ammonia (NH-SCR). Thus, our work describes, for the first time, the one-pot synthesis of Fe-modified NH-SCR catalysts supported on MCM-22, MCM-36, and ITQ-2. The calculated chemical composition of the materials was Si/Al of 30 and 5 wt.% of Fe. The reported results indicated a correlation between the arrangement of MWW layers and the form of iron in the zeolitic structure. We have observed that one-pot synthesis resulted in high dispersion of Fe sites, which significantly enhanced low-temperature activity and prevented NO generation during the reaction. All of the investigated samples exhibited almost 100% NO conversion at 250 °C. The most satisfactory activity was exhibited by Fe-modified MCM-36, since 50% of NO reduction was obtained at 150 °C for this catalyst. This effect can be explained by the abundance of isolated Fe species, which are active in low-temperature NH-SCR. Additionally, SiO pillars present in MCM-36 provided an additional surface for the deposition of the active phase.
近年来，MWW拓扑结构的层状沸石在环境催化中的应用受到了越来越多的关注；然而，只有少数研究探讨了它们在氨选择性催化还原（NH-SCR）中的性能。因此，我们的工作首次描述了负载在MCM-22、MCM-36和ITQ-2上的铁改性NH-SCR催化剂的一锅合成法。所计算的材料化学组成为硅铝比为30且铁含量为5 wt.%。报道的结果表明MWW层的排列与沸石结构中铁的形态之间存在相关性。我们观察到一锅合成法导致铁位点高度分散，这显著提高了低温活性并防止了反应过程中NO的生成。所有研究的样品在250℃时几乎都表现出100%的NO转化率。铁改性的MCM-36表现出最令人满意的活性，因为该催化剂在150℃时实现了50%的NO还原率。这种效应可以通过大量在低温NH-SCR中具有活性的孤立铁物种来解释。此外，MCM-36中存在的SiO柱为活性相的沉积提供了额外的表面。
