Confirmation of NH species in the framework of nitrogen-incorporated ZSM-5 zeolite by experimental and theoretical studies
Confirmation of NH species in the framework of nitrogen-incorporated ZSM-5 zeolite by experimental and theoretical studies
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DOI：
10.1016/j.micromeso.2009.06.025
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发表时间：
2010
影响因子：
5.2
通讯作者：
Guangjun Wu;Xin Wang;Ya-li Yang;Landong Li;Guichang Wang;N. Guan
中科院分区：
文献类型：
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作者：
Guangjun Wu;Xin Wang;Ya-li Yang;Landong Li;Guichang Wang;N. Guan
掺氮沸石作为一类新的碱性固体材料而备受关注，氮原子有望被引入沸石的骨架中。本研究采用程序升温氮化法制备了掺氮ZSM-5沸石，并通过XRD、SEM和BET技术对其物理化学性质进行了表征。将详细的红外表征与理论红外模拟相结合，在掺氮沸石的红外指纹区域中观察到与 1151 和 985cm−1 处桥接 Si-N(H)-Si 基团相关的谱带。结果证实，N原子通过氮化作用被引入到ZSM-5沸石的骨架中，形成碱性-NH-物种，29Si MAS NMR表征结果也证实了这一点。此外，通过苯甲醛和丙二腈的Knoevenagel缩合评价了掺氮ZSM-5沸石的基本催化性能，并提高了苯甲醛的转化率。
Nitrogen-incorporated zeolites have drawn much attention as a new family of basic solid materials and N atoms are expected to be introduced into the frameworks of zeolites. In this study, nitrogen-incorporated ZSM-5 zeolites were prepared by temperature-programmed nitridation and their physicochemical properties were characterized by means of XRD, SEM and BET techniques. Combined a detailed IR characterization with a theoretical IR simulation, the bands relating to bridging Si–N(H)–Si groups at 1151 and 985cm−1were observed in the IR fingerprint region of nitrogen-incorporated zeolites. The results confirmed that N atoms have been introduced into the framework of ZSM-5 zeolites by nitridation to form basic –NH– species, which was also supported by results of29Si MAS NMR characterization. Furthermore, the basic catalytic properties of nitrogen-incorporated ZSM-5 zeolites were evaluated by Knoevenagel condensation of benzaldehyde and malononitrile and enhanced conversion of benzaldehyde was achieved.