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Characteristics of Dehydrogenation Catalysis at Solid-liquid Interface Kept with Any Temperature Gradient

任意温度梯度固液界面脱氢催化特性

基本信息

批准号：
07650943
负责人：
SAITO Yasukazu
金额：
$ 1.34万
依托单位：
Science University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Carbon-supported metal catalysis dipped with insufficient amounts of organic substrates (hereafter termed as "liquid-film states") have been found to exhibit strikingly-enhanced activities of dehydrogenation under boiling conditions in comparison with those of suspended catalyst states. Following characteristics were observed at the adequate ratio of catalyst amounts to substrate amounts :(1) The rates of evaporation from the substrate liquid phase were decreased.(2) Temperatures of the catalyst layr were higher than that of the boiling liquid bulk.(3) Vigorous evolution of bubbles occurred not only from the liquid bulk but also from the powder surfaces of carbon-supported catalysts.(4) Evolved bubbles can pass through the liquid film with insufficient gas-liquid equilibration, supplying product-rich components to the gas phase.(5) Product hydrogen were separated from the substrate vapor by fractional condensation, which resulted in no possibility of hydrogen return to the boiling reaction solution.(6) The substrate was condensed at low temperatures and supplied directly to the catalyst, with advantageous adsorption and predominant coverage assured.Consequently, kinetically-controlled dehydrogenation with catalysts in liquid-film states under boiling conditions undergoes at high reaction rates and one-path conversions. Product desorption from the catalyst would be coupled with the temperature gradient at the solid-liquid interface, for which common thermodynamic features are pointed out with those of "thermal diffusion" (Prigogine, 1947). Various kinds of experimental evidence were obtained for catalytic dehydrogenation of 2-propanol as well as of cyclohexanes.

已经发现，与悬浮催化剂状态相比，用不足量的有机底物浸渍的碳负载金属催化剂（以下称为“液膜状态”）在沸腾条件下表现出显着增强的脱氢活性。在催化剂量与基质量比例适当的情况下，观察到以下特征：（1）基质液相的蒸发速率降低。（2）催化剂层的温度高于沸腾液体本体的温度。（3）气泡不仅从液体本体中发生剧烈的演化，而且从碳负载催化剂的粉末表面发生。（4）气泡的演化 (5)产物氢通过分凝从底物蒸气中分离出来，氢不可能返回到沸腾的反应溶液中。(6)底物在低温下冷凝，直接供给催化剂，吸附性好，覆盖性好因此，在沸腾条件下采用液膜状态的催化剂进行动力学控制的脱氢反应可以实现高反应速率和单程转化。催化剂上的产物解吸与固液界面处的温度梯度相关，并指出了“热扩散”的共同热力学特征（Prigogine，1947）。获得了 2-丙醇和环己烷催化脱氢的各种实验证据。