Catalytic Activation of Lower Alkanes under Carbon Dioxide Atmosphere

本研究旨在探讨在二氧化碳气氛下由低烷烃生产多支高脂肪烃的可能性，并得到以下结果。(1)二氧化碳对乙烷芳构化的加速作用证实了二氧化碳对Ga-ZSM-5催化剂上乙烷芳构化的加速作用，其作用澄清为加速乙烯低聚的动力学效应，而非逆水气变换反应中氢气消耗的热力学效应。(2)丙烷芳构化产物分布的控制因素采用多种MFI结构的Ga-硅酸盐进行丙烷芳构化实验，阐明了丙烷芳构化产物分布的控制因素，发现催化活性和选择性主要取决于硅酸盐晶格中含有骨架Ga离子的酸量以及骨架外Ga-氧化物的量和粒径。初步将神经网络应用于催化性能的估计，以期建立一个分析复杂催化反应的催化活性和选择性控制因素的计算机系统。(3)丙烷在ga -氧化物催化剂上的结构活性关系制备了多种类型的ga -氧化物，并应用于丙烷脱氢的催化运行，发现丙烷脱氢是一个结构敏感的反应，需要大的Ga2O3颗粒。活性还取决于氧化物中Ga离子的局部结构。(4)甲烷活化在溴化物存在下，甲烷可以在450℃以下的低温条件下在多种氧化物催化剂上转化。在该催化体系中加入芳构化催化剂，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.