Kazuo Makino

Activity tests of various catalysts for hydrocracking of coal by means of high pressure differential thermal analysis

Abstract The activities of fourteen kinds of catalysts for the hydrocracking of Taiheiyo coal were examined by a high pressure differential thermal analytical method. Exothermic peaks appeared at low temperatures (420–430°C) when MoO3TiO2, NiY zeolite and CoY zeolite were used as catalysts, indicating that these catalysts are highly active compared with other catalysts including MoO3CoOAl2O3. The qualitative analysis of gas and liquid products revealed that MoO3TiO2 and CoY are good catalysts for the liquefaction reaction. The hydrogenation ability of the catalyst is concluded to be more important than its acidic property.

High temperature, high pressure ESR study of molybdenum-containing catalysts

Abstract The reduction of molybdenum in molybdenum trioxide over various supports was studied using high-temperature, high-pressure ESR techniques. The support materials have a great influence on the reduction behaviour of the catalysts at high temperatures under a high pressure of hydrogen. The ease of reduction of molybdenum in the order MoO 3 /SnO 2 > MoO 3 /ZrO 2 > MoO 3 /TiO 2 > MoO 3 /Al 2 O 3 > MoO 3 /SiO 2 > MoO 3 /MgO. To clarify the interaction between catalysts and reactants, the molybdenum-containing catalyst-9-methylanthracene system was monitored. An electron-transfer reaction from 9-methylanthracene to catalysts occurred and both organic radicals and Mo(V) species were observed at the same time. It was found that the behaviours of organic radicals and Mo(V) species depend on the support materials, i.e. the organic radical concentration increases with increasing Mo(V) concentration for the MoO 3 -Al 2 O 3 -9-methylanthracene system in the temperature range 381 – 558 K. On the other hand, the organic radical concentration is inversely proportional to Mo(V) concentration for the MoO3-ZrO2-9-methylanthracene system in the range 399 – 493 K.

In-situ monitoring of the stabilization with hydrogen of free radicals thermally induced from coal using high pressure e.s.r., d.t.a. and p.d.a. equipment

Abstract High temperature, high pressure e.s.r. measurements of the hydrogenation reaction of Taiheiyo coal in the presence of catalysts were carried out to understand the stabilization of thermally and/or catalytically induced free radicals. A decrease in free radical concentration with increasing temperature was observed for ZnCl 2 and SnCl 2 · 2H 2 O catalysts at 10MPa under hydrogen gas. High pressure modified single-cell d.t.a. and p.d.a. equipment augmented the uniquely designed high temperature, high pressure e.s.r. cell. The hydrogenation reaction was monitored under the same experimental conditions as for e.s.r. From the results of the combination of high temperature, high pressure e.s.r. with high pressure d.t.a. and p.d.a., it was established that H 2 molecules can react efficiently with free radicals from coal molecules created by the presence of ZnCl 2 and SnCl 2 · 2H 2 O catalysts.

Application of carbon microbeads for column packing for high-performance liquid chromatography

Carbon microbeads have been recognized as an advanced carbonaceous material with exciting possibilities just like carbon fibre. Among their potential applications are high-density, high-strength, isotropic carbon solids [1] and bulking agents for liquid chromatography [2]. The microbeads have usually been obtained by carbonizing pitch, separating them from each other with solvent or in a high-temperature centrifuge. To name a few advantages of carbon microbeads, they offer (a) high resistance to very acidic and very basic reagents, (b) low expansion and shrinkage coefficients and (c) the ability to withstand an operating temperature of 250 °C. Recently we have developed a method for obtaining carbon microbeads from n-paraffin or a mixture of n-paraffin and coal tar pitch (CTP) under mild conditions at 873 K under a nitrogen pressure of 2 MPa [3, 4]. In this letter a study is made on the application of carbon microbeads for column packing for highperformance liquid chromatography (HPLC) for the separation of aromatic and polar compounds. n-Paraffin (melting point 341 to 343 K) was used as the starting material for production of carbon microbeads. Carbonization of paraffin was performed in a 15 ml autoclave. The autoclave charged with an 0.8 g sample was pressurized with nitrogen at an initial pressure of 5 MPa and put into an image furnace for carbonization at 873 K (the yield of carbon microbeads was 18 wt %). The rate of heating was 5 K min-~. The carbon microbeads formed in the autoclave were taken out and were heat-treated further at 973, 1073 and 1173 K for I h under nitrogen gas flow. Heat-treated carbon microbeads thus obtained were tested as a Figure 1 SEM micrographs of carbon microbeads from n-paraffin used for HPLC column packing.

Reactivity of coals in hydrogenation

Abstract Three coals of different rank (77.9–89.5 wt% C, daf) were hydrogenated at various temperatures to examine the influence of coal rank on the hydrogenation reactivity. Extraction of the heat treated coals with pyridine, benzene and n -hexane was also carried out to estimate the total amount of the intrinsic solvent-soluble fraction in the original coal. In the extraction of preheated coal, the largest amount of pyridine-soluble fraction was obtained for the coal of medium rank (83.9% C). This coal also showed the highest conversion, in terms of pyridine solubility, on hydrogenation. As the pyridine soluble material from hydrogenation must contain the intrinsic soluble fraction present in the original coal, it cannot be concluded that medium-rank coal shows the highest reactivity in hydrogenation. Conversion to benzene and n -hexane soluble materials is only slightly affected by the intrinsic soluble fraction, so it is better to estimate hydrogenation reactivity from the yields of these materials. On this basis, the lowest-rank coal shows the highest reactivity in hydrogenation.

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 thiol<diphenyldisulfide<phenylsulfide<thiophen <benzothiophen. 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).