The US Synfuel Development Program was strongly accelerated after each of the two oil crisis. As the oil price declined, and under the Reagan administra-tion with policy change putting emphasis on market mechanism, however, almost all syn-fuel development projects were discontinued. In the U S. the energy issue has lost its attractiveness among the policy makers and the Program, which had originally been con-ceived to address a national security issue, had to be transformed to a program to address the issue of enviromental protection. Consequently, the Program was renamed to be called “Clean Coal Technology Program”. Stimulated by the U S, Japan started her Synfuel Development Program. It has been maintained on a large scale even after the decline of oil prices, which now makes Japan the only country with a strong synfuel development program being implemented. The differences in the energy policy between the U S and Japan can be explained by the difference in the situation in the two countries in terms of domestically available energy resources, role of the government, R&D budget and the basic economic measures.
The recent status of catalytic hydrogenation of carbon dioxide to methanol was investigated. Although catalytic hydrogenation of CO2 requires H2 and energy, it shows much higher reaction rate than other CO2 conversion technologies. Especially, conversion to methanol is a promising technology because of its excellent characteristics as a fuel. Thermodynamically, lower temperatures and lower pressures are favorable for methanol synthesis from CO2 and higher temperatures are favorable for the reverse water gas shift reaction. Thus, a catalyst which is highly active below 473 K promises low-energy conversion to methanol. CO2 hydrogenation technology is classi-fied into a gas-phase synthesis and a liquid-phase synthesis from its reaction method. In the gas-phase synthesis, Cu/ZnO-based catalysts show space time yields comparable to those in the conventional methanol production process from syngas. The liquid-phase synthesis employing a homogeneous catalyst is expected to operate at lower temperatures than the gas-phase synthesis. In order to achieve efficient CO2 conversion to methanol, it is necessary to develop an active catalyst system at lower temperatures.
A new preparation method of molybdenum sulfide catalysts was in-vestigated using sulfur-containing organometallics in order to improve hydrogenation (HY) activities of the catalysts. Mo and Ni-Mo catalysts were prepared by impregant-ing sulfur-containing organometallics onto an alumina support. After drying and calcin-ing in N2, model test reactions were carried out to evaluate HY activities of newly pre-pared catalysts. Hydrogenation of aromatic rings proceeded to a large extent over new types of Mo catalysts prepared using sulfur-containing Mo organometallics. This is mainly due to much higher dispersion of MoS2 species on the catalysts than those on con-ventional catalysts prepared using impregantion of inorganics, calcination in air, and presulfurization. Sulfur-containing Ni organometallics also gave higher HY activities of Ni-Mo catalysts as compared to Ni inorganics such as nickel nitrate. The highest HY activities of Ni-Mo catalysts were obtained when molybdenum dithiophosphate and nickel dialkyl-dithiocarbamate were used for catalyst preparation. This new preparation method of the sulfide catalysts clearly showed forther possibility of considerable im-provement in sulfide catalyst preparation.
Lump coke size is determined mainly by the growth of macro-crack from the wall side to center in the coke oven chamber, where the carbonization period and the coke quality are determined by the heat and mass transfer. Although the radia-tive heat transfer of porous media within the micro-crack can be included in an effective thermal conductivity, the effect of radiative heat transfer within the macro-crack on temperature and stress distribution in coal/coke layer have to be investigated analytical-ly using the finite element method. In this study, a rapid heating experiment of the brick with a macro-crack is carried out in the laboratory-scale coke oven to measure the temperature distribution in the brick. The heat transfer model including the radiative heat transfer within the macro-crack is estimated by comparing the calculated result with the experimental one in order to confirm the accuracy of temperature field in our ordinary thermal stress analysis model. As a result, the calculated history of temperature distribution in the sam-ple brick is in good agreement with experiments especially near the macro-crack surface.
Coal liquefaction experiments for Taiheiyo coal with decrystallized anthracene oil as the solvent and red-mud/sulfur as the catalyst were conducted by a batch reactor with rapid heating operation and, a bench-scale continuous preheater. Rate constants were obtained from analysis of the experimental results by two reactants model. Moreover, the coal conversion in a continuous liquefier was estimated with these rate constants by the perfect mixed reactor model. The coal liquefaction rates of the less active component for Taiheiyo coal were diffe-rent between the batch reactor and the continuous reactor, with decrystallized anthracene oil as the solvent. It was considered that the reason was due to the differ-ences in the doner hydrogen concentration of the two reactors. The observed values of the coal conversion were approximately coincided with the calculated values. Therefore, it was found that the frequency factor of the reaction rate of the less active coal components varied with both the pressure and the reactor types, but the activation energy did not change. Effect of vaporization of the solvent on the values of the residence time of slurry could be neglected in these experimental conditions (30 MPa, 723 K), and they were represented by the values caluculated using only the gas holdup.
Effect of Ni and Fe ions, which were loaded to Loy Yang brown coal by ion-exchange method, on flash hydropyrolysis was investigated, using a bench-scale apparatus. The steam gasification reactivity of the chars prepared from flash hydropy-rolysis of the coals were also investigated using thermo-balance. The following results were obtained. 1) It was confirmed that Ni and Fe significantly increased the overall carbon con-version in hydropyrolysis of coals. At the same time, they promoted the con-version of liquids and BTX to methane, so it is important for obtaining more li-quids and BTX to select a proper reaction condition. 2) The steam gasification reactivity of the chars prepared from flash hydropyroly-sis of metal loaded coal were remarkbly higher than that of the chars prepared from the original coal.
Thermodynamic analyses were done for better understanding of the structural changes in iron based coal liquefaction catalysts during sulfidation and oxida-tion. Chemical potential diagrams were used to evaluate the stability/reactivity of several iron phases such as Fe, Fe3O4 (magnetite), Fe2O3 (hematite), Fe0.877S (Pyrrhotite), FeS2 (phyrite), FeSO4, and Fe2 (SO4) 3. These analyses indicated that most of the iron starting materials would be converted into thermodynamically stable phase Fe0.877S under typical coal liquefaction conditions, i.e., reaction temperature of 698K under reducing/sulfiding conditions. However, the sulfidation paths were quite different in Fe2O3 and FeSO4 as the starting materials, and were influenced significantly by the sul-fidation conditions, such as temperature, P (H2S) /P (H2) and P (H2O). These analyses suggested that steaming conditions would facilitate the sulfidation, but cause the gas phase transport of hydrated compounds, which might be one of the reasons for catalyst agglomeration.