Incorporation of various heterometal atoms in CHA zeolites by hydrothermal conversion of FAU zeolite and their performance for selective catalytic reduction of NOx with ammonia
Incorporation of various heterometal atoms in CHA zeolites by hydrothermal conversion of FAU zeolite and their performance for selective catalytic reduction of NOx with ammonia
复制标题
DOI：
10.1016/j.micromeso.2017.03.018
复制
发表时间：
2017-07
影响因子：
5.2
通讯作者：
T. Takata;Nao Tsunoji;Yasuyuki Takamitsu;M. Sadakane;T. Sano
中科院分区：
文献类型：
--
作者：
T. Takata;Nao Tsunoji;Yasuyuki Takamitsu;M. Sadakane;T. Sano
通过水热转化法将杂金属引入到CHA型铝硅酸盐分子筛（[Al，M]-CHA，M = Fe，Ga，Sn）中。X射线粉末衍射（XRD）、扫描电子显微镜、漫反射紫外-可见光谱、魔角旋转NMR和氮吸附测量证实了具有占据均匀分布的四面体配位位点的杂金属原子的[Al，M]-CHA沸石的形成。使用[Al，M]-FAU的水热转化的选择是由于不能由无定形水凝胶制备[Al，M]-CHA沸石。采用XRD、电喷雾质谱和紫外-可见光谱对[Al，Fe]-FAU水热转化为[Al，Fe]-CHA进行了表征。合成过程中的液相和固相分析表明，固相中存在的金属物种在转化过程中起着重要作用。我们还研究了负载Cu的CHA沸石用于氨选择性催化还原（SCR）NOx（NH3-SCR）的有效性。[Al，M]-CHA分子筛中杂金属原子的种类和数量对催化性能有很大的影响。虽然所有新鲜的催化剂表现出类似的NO转化效率，有一个在低反应温度下的NH3转化效率的差异。Cu负载的[Al，Ga]-CHA在150 °C下提供几乎100%的NH3转化率。[Al，Sn]-CHA催化剂在900 °C水热处理4 h后仍具有较高的稳定性。这些结果证实水热转化是合成具有高NH3-SCR性能的杂金属掺入沸石催化剂的有效方法。
Heterometal atom incorporation in CHA aluminosilicate zeolites ([Al, M]-CHA, M = Fe, Ga, Sn) was successfully achieved by hydrothermal conversion of heterometal-incorporated FAU aluminosilicates ([Al, M]-FAU). X-ray powder diffraction (XRD), scanning electron microscopy, diffuse reflectance UV–vis spectroscopy, magic angle spinning NMR, and nitrogen adsorption measurements confirmed the formation of [Al, M]-CHA zeolites with heterometal atoms occupying homogeneously distributed tetrahedral coordination sites. The choice of hydrothermal conversion using [Al, M]-FAU was prompted by the inability to produce [Al, M]-CHA zeolites from amorphous hydrogels. The hydrothermal conversion of [Al, Fe]-FAU to [Al, Fe]-CHA was characterized by XRD, electrospray ionization mass spectrometry, and UV–vis spectroscopy. Analyses of liquid and solid phases during synthesis indicated that metal species present in the solid phase play an important role in the transformation process. We also investigated the effectiveness of Cu-loaded CHA zeolites for the selective catalytic reduction (SCR) of NOxby ammonia (NH3-SCR). Catalytic performance depended strongly on the kind and/or amount of heterometal atom in the [Al, M]-CHA zeolite. Although all fresh catalysts exhibited similar NO conversion efficiencies, there was a difference in NH3conversion effectiveness at low reaction temperatures. Cu-loaded [Al, Ga]-CHA provided almost 100% NH3conversion at 150 °C. The [Al, Sn]-CHA catalyst exhibited high stability even after hydrothermal treatment at 900 °C for 4 h. These results confirm hydrothermal conversion as an effective method for synthesizing heterometal-incorporated zeolite catalysts with high NH3-SCR performance.