离子交换法制备的Fe-ZSM-5和K-Fe-ZSM-5分子筛,经不同温度水热处理后作为催化剂应用于N2O为氧化剂的苯一步氧化制取苯酚反应中.实验中,采用XRD、N2-吸附仪、NH3-TPD、27A1 MAS NMR、FT-IR、UV-vis和H2-TPR等方法对催化剂进行表征.结果显示:离子交换制备的Fe-ZSM-5分子筛,部分Fe离子以Fe2O3形式负载于分子筛的孔道中.经水热处理,分子筛骨架脱铝导致Brφnsted酸性位减少,而Fe2O3离子发生迁移形成活性Fe离子位.在苯一步氧化制苯酚反应中,N2O分子吸附于Fe离子位生成α-O.活性评价结果显示,水热处理前后,催化剂分解N2O性能不变,但苯酚选择性随水热处理温度的升高而逐渐降低.此外,K离子的引入将导致催化剂选择性的降低.%Fe-ZSM-5 and K-Fe-ZSM-5 zeolites were prepared by ion-exchange,followed by hydrothermal treatment at different temperature.After characterization by means of XRD,nitrogen adsorption/desorption,NH3-TPD,27A1 MAS NMR,FT-IR,UV-vis and H2-TPR,the samples have been investigated as catalysts for the one step oxidation of benzene to phenol by N2O as oxidizing agent.The results show that part of Fe2O3 particles are loaded on the surface and the pore of the Fe-ZSM-5 zeolite by ion-exchange.After hydrothermal treatment,Fe-ZSM-5 zeolite occurs framework dealumination and Brφnsted acid sites is decreased; The amounts of Fe2O3 particles decrease and iron-ions can be migrates to form highly active Fe3+ sites.These result in that N2O molecules can be adsorbed on these highly active Fe3+ sites and decompound to α-O.Before and after hydrothermal treatment,N2O conversion is almost unchanged in one step oxidation of benzene to phenol.Phenol selectivity is gradually increased with increasing temperature of hydrothermal treatment.However,the phenol selectivity is decreased because kalium ion is introduced into Fe-ZSM-5 zeolite.
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