Characterization and catalytic performances of three-dimensional mesoporous FeSBA-1 catalysts.
Characterization and catalytic performances of three-dimensional mesoporous FeSBA-1 catalysts.
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DOI：
10.1021/jp061523h
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发表时间：
2006-05
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通讯作者：
A. Vinu;T. Krithiga;V. Balasubramanian;A. Asthana;P. Srinivasu;T. Mori;K. Ariga;G. Ramanath;P. G. Ganesan
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作者：
A. Vinu;T. Krithiga;V. Balasubramanian;A. Asthana;P. Srinivasu;T. Mori;K. Ariga;G. Ramanath;P. G. Ganesan
以十六烷基三乙基溴化铵为模板剂，首次在强酸性介质中合成了铁取代立方笼型介孔分子筛（FeSBA-1）。通过调整盐酸与硅的摩尔比，可以很容易地控制SBA-1中铁的掺入量。通过原子吸收光谱（AAS）、x射线衍射（XRD）、N2吸附、紫外-可见DRS、XPS和ESR光谱对材料进行了表征。原子吸收光谱（AAS）、x射线衍射（XRD）和N2吸附结果表明，铁原子可以在不改变结构顺序和织构参数的情况下加入SBA-1基体。利用XPS光谱对FeSBA-1中铁原子的性质和配位进行了广泛的研究，结果表明FeSBA-1中大部分铁原子处于+3配位态。UV-Vis DRS和ESR研究证实，FeSBA-1中的大部分铁原子存在于四面体配位环境中（很可能占据骨架位置）。以叔丁醇为烷基化剂，在不同铁含量的FeSBA-1催化剂上进行了苯酚的叔丁化反应，并与一维介孔催化剂进行了比较。研究了反应温度、投料比、失重时空速、流上时间等参数对FeSBA-1活性和选择性的影响。在优化后的反应条件下，FeSBA-1（36）催化剂对苯酚叔丁化反应的催化性能优于一维介孔催化剂。
Iron substituted cubic cage type mesoporous molecular sieves (FeSBA-1) were synthesized for the first time in a highly acidic media using cetyltriethylammonium bromide as a template. The amount of Fe incorporation in SBA-1 can easily be controlled by the simple adjustment of the molar hydrochloric acid-to-silicon ratio. All the materials were unambiguously characterized by AAS, XRD, N2 adsorption, UV-Vis DRS, XPS, and ESR spectroscopy. The results from AAS, XRD, and N2 adsorption reveal that the iron atom can be incorporated in the framework of SBA-1 matrix without altering the structural order and the textural parameters. The nature and the coordination of iron atoms were extensively studied by XPS spectroscopy, and the results revealed that most of the iron atoms in FeSBA-1 are in +3 coordination state. UV-Vis DRS and ESR studies confirmed that the majority of the Fe atoms in FeSBA-1 exist in a tetrahedral coordination environment (most probably occupying framework positions). tert-Butylation of phenol employing tert-butanol as the alkylation agent was carried out over FeSBA-1 catalysts with different iron content and the results are compared with one-dimensional mesoporous catalysts. The influence of various reaction parameters such as reaction temperature, reactant feed ratio, weight hourly space velocity, and time-on-stream affecting the activity and selectivity of FeSBA-1 were also studied. Under the optimized reaction conditions, the FeSBA-1(36) catalyst showed superior catalytic performance for the tert-butylation of phenol as compared to the uni-dimensional mesoporous catalysts.