Effect of diffusion in catalytic dehydration of alcohol over silica-alumina with continuous macropores
Effect of diffusion in catalytic dehydration of alcohol over silica-alumina with continuous macropores
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DOI：
10.1016/j.jcat.2004.10.010
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发表时间：
2005
影响因子：
7.3
通讯作者：
Ryōji Takahashi;S. Sato;T. Sodesawa;K. Arai;Miyuki Yabuki
中科院分区：
文献类型：
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作者：
Ryōji Takahashi;S. Sato;T. Sodesawa;K. Arai;Miyuki Yabuki
以正硅酸四乙酯为原料，在聚氧乙烯的存在下制备了具有连续大孔和中孔的硅铝双峰多孔催化剂，并通过与无大孔的硅铝进行对比，评价了大孔在2-丙醇气相脱水中的效果。脱水反应速率取决于颗粒大小、大孔的存在以及反应温度。对于更详细的数据处理，通过假设催化剂有和没有大孔隙时的分子扩散和Knudsen扩散，理论上计算了每个反应温度下孔隙中的扩散系数。然后，将实验得到的催化剂效能因子与理论曲线进行了比较。实验数据与理论预测吻合较好。结果清楚地表明，具有相互连接结构的大孔有效地为快速扩散提供了途径，提高了反应动力学。
Bimodal porous silica–alumina catalysts with both continuous macropores and mesopores were prepared from tetraethyl orthosilicate in the presence of polyethylene oxide, and the effectiveness of macropores in vapor-phase dehydration of 2-propanol was evaluated by the comparison with silica-alumina having no macropores. The reaction rate of dehydration varies depending on the particle size and the presence of macropores as well as reaction temperature. For more detail data processing, diffusion coefficients in pores at each reaction temperature were theoretically calculated by assuming molecular diffusion and Knudsen diffusion for catalysts with and without macropores, respectively. Then, we compare the catalyst effectiveness factors obtained experimentally with the theoretical curve. The experimental data well agree with theoretical prediction. The results clearly show that the macropores with interconnected structure effectively work as pathways for rapid diffusion and improve the reaction kinetics.