Snpecriecd fluid as a reaction media for solid catalyzed reaction

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There are some problems in a conventional process of hydroreforming of eforming hydrocarbons. One problem is coking on the solid catalyst. When a liquid solvent is employedt as a reaction media, slow mass transfer rate in a liquid phase sometimes limits the process performance while the wlbing probrem is solned. In a procese for denitrogenation from coal tar pitch through catalytic hydrogenation, there are such roblems, the reaction is in three phases (hydrogen gas phase, molten pitch phase and solid catalyst). Diffusion of hydrogen in a molten pitch onto the catalyst is very slow and coking on the catalyst is significant. We applied supercritical toluenetetralin as a reaction media for this process, expecting homogeneous reaction atmosphere and in-situ removal of coke from the catalyst surface. We found out that the reaction rate was enhanced and coke formation was suppressed in a supercritical phase. To elucidate the reason for this enhancement of the reaction, the effect of the particle size on the reaction rate was examined and the results were compared for supercritical phase (toluenel tetralin) and liquid phase reaction (1-methyl naphthalenel tetralin). Even under the control of chemical reaction, the reaction rate in supercritical phase is faster than that in liquid phase, especially for the base nitrogen compounds (carbazol, etc.), rather than for the neutral nitrogencompounds (benzo-quinoline etc.)For the elucidation of the machanism, carbazol was employed as a model compound for this reaction. The main reaction pathways were elucidated and the kinetics for the reaction was evaluated. With reducing pressure from 15 to 5 MPa, the reaction rate of enitrogenation was decreased to be half. This can be explained by both the variations of eauiriburium constant and that of elementary rate constants.