Catalytic Activation of Lower Alkanes under Carbon Dioxide Atmosphere

本研究旨在探讨低碳烷烃在二氧化碳气氛下生产多支化高级脂肪烃的可能性，得到了以下结果：(1)在Ga-ZSM-5催化剂上，二氧化碳对乙烷芳构化的加速作用被证实是促进乙烷芳构化的动力学效应，而不是通过逆水煤气变换反应消耗氢引起的热力学效应。(2)丙烷芳构化产物分布的控制因素用各种具有MFI结构的镓硅酸盐进行丙烷芳构化，阐明了丙烷芳构化产物分布的控制因素初步将神经网络应用于催化性能评价，开发了复杂催化反应活性和选择性控制因素的计算机分析系统。(3)丙烷脱氢反应的结构活性关系制备了不同类型的氧化镓催化剂，并将其应用于丙烷脱氢反应的催化运行，发现丙烷脱氢反应是一个结构敏感的反应，需要较大的氧化镓颗粒。催化剂的活性还取决于氧化物中Ga离子的局部结构。(4)甲烷活化甲烷在溴化物存在下，甲烷在较低的温度(450ﾟC)下能够转化为甲烷。在该催化体系中加入芳构化催化剂，可在较高温度下生成少量芳香族化合物。

The present research aims at examining the possibility of production of multi-branched higher aliphatic hydrocarbons from lower alkanes under carbon dioxide atmosphere, and the following results were obtained.(1) Acceleration of Ethane Aromatization by Carbon DioxideCarbon dioxide was confirmed to accelerate the aromatization of ethane over Ga-ZSM-5 catalysts, and its effect was clarified to be the kinetic effect to accelerate the oligomerization of ethylene, but not thermodynamic effect due to the consumption of hydrogen through reverse water gas shift reaction.(2) Factors Controlling Product Distribution of Propane AromatizationPropane aromatization was conducted by using various Ga-silicate with MFI structure to elucidate factors controlling product distribution of propane aromatization, and it was found that the catalytic activity and selectivity depend mainly on the acid amount due to framework Ga ions incorporated in silicate lattice and on the amount and the particle size of extra-framework Ga-oxide.A neural network was preliminarilly applied for the estimation of catalytic performance in order to develop a computer system for the analysis of factors controlling catalytic activity and selectivity of complicated catalytic reactions.(3) Structure Activity Relationship in Dehydrogenation of Propane on Ga-oxide Catalystvarious types of Ga-oxides were prepared and applied for the catalytic runs of propane dehydrogenation, and it was found that the propane dehydrogenation is a structure sensitive reaction demanding large Ga2O3 particles. The activity also depends on local structure of Ga ions in oxide.(4) Methane ActivationMethane was able to be converted at lower temperature such 450ﾟC in the presence of bromine compound on various oxide catalysts. A minor amount of aromatic compounds were formed at higher temperature by adding aromatization catalyst to this catalytic system.