The properties of coal when the coal was hydrothermally treated at 150-350°C were examined with particular emphasis on the surface properties. The analysis of coal properties includes hygroscopicity, the content of functional groups measured by chemical analysis and FT-IR, elemental analysis, specific surface area, maceral composition, and vitrinite reflectance. Two Australian low rank coals, Loy Yang coal and Yallourn coal, were tested; while a subbituminous coal and a high rank coal were subjected to the same treatment for comparison. When the low rank coals were hydrothermally treated, the hygroscopicity of coal remarkably decreased, becoming comparable to that for high rank coals after the 350°C treatment. The content of carboxyl group greatly decreased as heat treatment temperature (HTT) was raised; whereas decrease in the content of phenolic hydroxyl group was rather small. After the hydrothermal treatment, exinite maceral in the coal almost disappeared and the absorbance for aliphatic carbon in FT-IR spectrum was somewhat raised. From these results, the change in the coal properties during the hydrothermal treatment is discussed.

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Catalytic combustion of propane/air mixture in a honeycomb monolith catalyst was investigated. Both experiment and numerical simulation were made at 573K inlet temperature, 0.48 to 1.74 m/s inlet velocity, and 0.15 to 0.30 equivalence ratio. In the experiment, gas temperatures were measured with thin thermocouples, and substrate temperatures with an optical fiber thermometer. In the numerical simulation, a two-dimensional, steady state model was developed to calculate the velocity, temperature, and propane concentration in the catalyst. In the model, chemical reaction on the catalyst surface was assumed to be one-step oxidation, with Arrhenius type reaction rates; reaction in the gas phase was neglected. Calculated temperature profiles agree qualitatively with those experimentally obtained.

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Using an upgraded low rank coal would be effective to decrease the preparation cost of a coal water mixture (CWM). Some upgrading processes for low rank coals have been developed in recent years. On the other hand, the surface characteristics of an upgraded coal would be more hydrohobic rather than a normal bituminous coal. Therefore, the selection of suitable additives for both fluidity and stability of CWMs with upgraded coals is important. In this study, Indonesian coal (Banjarsari -Tanjung Enim) was used to prepare a CWM and twelve surfactants and four stabilizers were examined. From the experimental results, a CWM with the addition of both condensation product of formalin and naphthalen sulfonic acid (NSF-Na⁺) and bio-polysaccharide (S-194) showed good fluidity and stability. The coal concentration of the CWM was 60.5 % at the apparenet viscoity of 1 Pa · s. The information obtained in this study for various kinds of additives should be valuable for the preparation of CWMs.

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