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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、27Al 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Brnsted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。
The Fe-ZSM-5 and K-Fe-ZSM-5 molecular sieves prepared by ion exchange method were used as catalysts in the one-step oxidation of benzene with N2O as oxidant to produce phenol through hydrothermal treatment at different temperatures. In the experiment, the catalysts were characterized by XRD, N2-adsorption, NH3-TPD, 27Al MAS NMR, FT-IR, UV-vis and H2-TPR. The results showed that Fe-ZSM-5 zeolite prepared by ion exchange and some Fe ions were supported on the pore of zeolite as Fe2O3. After hydrothermal treatment, dealuminization of molecular sieve framework leads to decrease of Brnsted acidity, while Fe2O3 ion migrates to form active Fe ion sites. In the one-step oxidation of benzene to phenol, N2O molecules adsorb to the Fe ion to form α-O. The results of the activity evaluation show that the catalyst decomposes N2O before and after the hydrothermal treatment, but the phenol selectivity decreases gradually with the increase of the temperature of the hydrothermal treatment. In addition, the introduction of K ions will result in a selective reduction of the catalyst.