Studies on high pressure hydrodesulfurization of aromatic sulfur compounds by a small differential thermal analysis apparatus.

A specified small differential thermal analysis unit was applied to the studies on hydrogenation of aromatic compounds and hydrodesulfurization of sulfur compounds in order to reveal the relationship between the hydrogenation reactions and exothermic peaks on the DTA curves and also to understand the characteristics of hydrodesulfurization of some organic sulfur compounds.The unit consists of two identical cylindrical cavities drilled symmetrically in a stainless steel block, which are available for above reactions.Hydrogenation of benzene and naphthalene was carried out with stabilized nickel as catalyst under 100 kg/cm2 G of initial hydrogen pressure and with a heating rate of 12. 4°C/min. One exothermic peak was observed for benzene and two ones for naphthalene. Chemical analysis showed that the peaks were based on the hydrogenation of benzene to cyclohexane, and of naphthalene to tetralin or tetralin to decalin.The DTA curves according to hydrodesulfurization of six sulfur compounds were also measured with molybdenum disulfide as catalyst under 100 kg/cm2 G of initial hydrogen pressure and with the same heating rate as the above. Exothermic peaks were observed for all sulfur compounds. These peaks were due to the hydrodesulfurization of them. The exothermic peak temperature shifted to higher temperatures in the order of thiolbenzothiophen. This indicates that severer reaction conditions are required for the hydrodesulfurization of the above sulfur compounds in this order described.It is concluded that the above analysis unit is available to check high pressure hydrogenation with ease using a very small charge (ca. 30 mg).