Snpecriecd fluid as a reaction media for solid catalyzed reaction

传统的烃类加氢重整工艺存在一些问题。一个问题是固体催化剂的焦化。当采用液体溶剂作为反应介质时，在解决流动问题时，液相中缓慢的传质速率有时会限制工艺性能。在煤焦油沥青催化加氢脱氮过程中，存在这样的问题，反应是三相的（氢气相、熔融沥青相和固体催化剂）。氢气在熔融沥青中向催化剂上的扩散非常缓慢，催化剂上的结焦非常明显。我们采用超临界甲苯四氟灵作为该工艺的反应介质，期望反应气氛均匀，催化剂表面能原位去除焦炭。结果表明，超临界相提高了反应速率，抑制了焦炭的生成。为了阐明反应增强的原因，考察了颗粒大小对反应速率的影响，并比较了超临界相（甲苯四萘林）和液相反应（1-甲基萘四萘林）的反应结果。即使在化学反应的控制下，超临界相的反应速率也比液相快，特别是碱类氮化合物（咔唑等）的反应速率比中性氮化合物（苯并喹啉等）的反应速率要快。为了阐明反应机理，我们选择咔唑作为模型化合物进行该反应。阐明了反应的主要途径，并对反应动力学进行了评价。当压力从15 MPa降低到5 MPa时，氮化反应速率降低到原来的一半。这可以用艾氏常数的变化和基本速率常数的变化来解释。

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.