Influence of gas atmosphere and coal particle size on coal pyrolysis behavior in spot heater apparatus was investigated in nitrogen, helium and argon atmosphere, and in the size range of 650-1300μm respectively. The inert gas with small thermal conductivity/specific heat provided fast heating and high final temperature, and coal sample in such an inert atmosphere was decomposed more largely and quickly. It turned out that particle size has influence on heating rate but almost no influence on final temperature of coal particle as long as heating time is long enough. Generally, pyrolysis weight loss of smaller coal particle is larger because of its higher heating rate and less residence time of volatiles in particle.

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In order to clarify the controlling factors for char gasification, characterization and CO_2 gasification of many different chars have been carried out. XRD analysis of the chars indicates that minerals in the brown coal greatly affect carbon structure of char during pyrolysis stage. Gasification results show that inherent minerals which can be removed by HCl washing catalyze char gasification.

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The CO_2 gasification reactivity of chars produced under a relatively mild condition was investigated after identifying the pore structures and surface oxygen-containing functional groups of the standard coal samples. The reactivity was evaluated by measuring the rate of thermogravimetric loss at the. Burn-off 10%. Attempts were made to predict the reactivity of chars produced under a condition of high temperature and pressure using the data. These data allowed estimation formula to be obtained by using ultimate analyses. It was expected that the reaction of coal chars in a severe condition could be predicted from the RP data.

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Desulfurization efficiency and reactivity of the coal which made it loaded Ca^<2+> by using the principle of electric double layer was estimated and it was compared with technics of loading Ca^<2+> to the coal generally done. Increase was observed by the amount of loading, which the electric double layer was used for comparison with the ordinal procedure of loading it more than 2-3 times. Furthermore the higher amount of Ca^<2+> loading could be obtained by varying the conductive of electrolysis and electrolyte. On the other hand, as for the reactivity as well, increase in several to a few percent was seen.

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Behavior of ion-exchanged Ca in coal during pyrolysis and CO_2 gasification was experimentally simulated using a mineral-matter-free coal sample. The sample was prepared from Loy Yang brown coal by a sequence of alkali-hydrolysis solubilization, solvent extraction, Ca-ion exchange and solvent removal. Upon heating the sample in N_2 atmosphere up to 1673K, the ion-exchanged Ca formed into particles of CaO or CaS with sizes of 10-20nm. CaO held at 1673K probably converted into Ca due to carbothermal reduction in char and Ca was volatilized to an extent of about 75% leaving the rest as CaS. On the other hand, the extent of Ca volatilization was negligible in CO_2 even after nearly complete char gasification. During CO_2 gasification, ion-exchanged Ca was mainly converted into composite or mixed oxide particles together with Si and Al which initially resided in the sample in organic forms.

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X-ray diffraction parameters of 10 CCUJ standard coals and their char were obtained by STAC-XRD (standard analysis of coal-X ray diffraction) and related with CO_2 reactivity of these samples. The char was prepared by rapid heating of the coals in a drop tube furnace. As a result, a good correlation was found between two parameters i.e., the average number of stacking layers and stacking index, and CO_2 reactivity data. This result suggests that the CO_2 reactivity depends on the stacking stracture in the raw coal as well as their char.

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Using anthracene and paraffin 151P as the model compounds, decomposition mechanism of Yallourn coal by microwave plasma reactions was investigated. As a plasma gas source, helium was continuously supplied under reduced pressure. Both anthracene and paraffin 151P were quickly gasified, and small amount of oily product was obtained. In the case of paraffin 151P, the yield of gaseous products was higher, while char yield was smaller in comparison with anthracene.

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We conducted steam gasification of various coal char under atomospheric pressure or pressurized conditions. Raw coal such as Adaro (SS-013) showed high hydrogen producibility at low temperature. And also alkaline metals catalyzed water gas shift reaction. From these results, we optimized the conditions for production of syngas from coal char and steam.

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SS004 coal was heat-treated at temperatures up to 1600℃. Kaolinite disappeared at 900℃ due to its change to meta-kaolinite. At temperatures above 1200℃, mullite was observable, and at 1500℃, as mullite disappeared, β-SiC became apparent with the formation of other phases such as Al_2O_3, AlN and Si_3N_4. SiC and AlN were the major products in the coal treated under N_2 at 1600℃. The interaction between coal char and mixtures of calcium oxide, quartz and kaolinite were investigated by heating to 1600℃. Calcium oxide was gradually reduced by coal char in the temperature ranging 950-1450℃, releasing CO. CaO was carbided fast above 1450℃. As CaO coexisted with meta-kaolinite, CaO reacted with meta-kaolinite below 1200℃. The SiO_2 component in the CaO-SiO_2-Al_2O_3 compound was more readily carbided than the Al_2O_3 component. Calcium oxide exerted a strong catalytic effect on the graphitization of coal char, mainly forming the graphitic carbon at 1600℃.

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Finely dispersed calcium compounds have a quite large catalytic effect for char gasification in O_2, CO_2 and steam. In this work, a new effective utilization of Ca ion-exchanged brown coal as not only a sorbent for desulfurization but also catalyst for char gasification in a brown coal fluidized-bed reformer was investigated. CaO produced from Ca ion-exchanged coal was much more reactive toward H_2S than that from limestone. CaS involved in the Ca-exchanged char reacted with H_2S have a large catalytic effect for the char gasification in steam. It is concluded that ultra fine CaO particles in the char can play important roles not only in the desulfurization as a highly efficient sorbent but also in the gasification of coal char as a catalyst.

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Various biobriquettes made by mixing three Chinese bituminous coals and three types of biomass like agricultural and forest wastes were heat-treated at 1173K in nitrogen. Each biobriquette char obtained was then gasified with steam at 1073-1273K and 0.012-0.069MPa as the partial pressure to measure the reactivity. Results under identical gasification conditions showed the followings: (1) Biobriquette chars had larger reaction rates than the corresponding coal chars used for comparison. When Ca(OH)_2 as desulfurization agent was added, the reactivities of biobriquette chars were further enhanced to the same level of that for brown coal. (2) Increase of the rate in the presence of biomass and by addition of Ca(OH)_2 can be explained by such a situation that the portion of biomass would be preferentially gasified, thereby the contact area between unreacted coal char and steam could be increased and by combined catalytic effect of inherent biomass ash and calcium component, respectively. (3) For the composition of gases evolved, it depended on the ratio of coal/biomass in weight, gasification temperature, and the partial pressure of steam, indicating the controllability of H_2/CO ratio by selecting these operating factors.

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A new non-evaporative coal dewatering method was presented, in which a bed of coal was contacted with a flowing non-polar solvent at less than 200℃. Water in coal was released by thermal energy added and the released water was dissolved into solvent and was carried away from the coal bed. When the solvent was recovered at room temperature, most of water is separated from the solvent due to the decrease in the solubility of water in the solvent. Then the water is easily separated from the solvent by decantation. This method, therefore, removes water without causing phase change of water. When an Australian brown coal whose water content was 50% was treated by tetralin at 150℃, the water content was reduced to less than 2%.

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Five kinds of coals were pretreated in methanol solution at an ambient temperature. Untreated and treated coals were ground in a boll mill. The ground coal samples were observed and analyzed with CCSEM. Mineral matters were effectively liberated from organic matters by the methanol pretreatment. A centrifugal separation was conducted. Organic matter recovery and mineral matter reduction were improved by the pretreatment.

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Sulfur reduction from diesel-fuel is a current key technology to prevent air-pollution. With a view to improving the hydrodesulfidation (HDS) process, we examined the HDS activity of comminuted MoS_2 fine particles by autoclave test. The comminuted MoS_2 fine particles catalyzed more HDS of 4,6-dimethyldibenzothiophene (4,6-DMDBT) than that of dibenzothiophene (DBT). This is a inverse result in comparison with the conventional HDS catalyst, CoMo/γ-Al_2O_3, indicating that a bubble column reactor system with the MoS_2 fine particle is a plausible for a HDS process satisfying the future strict regulation value of the sulfur content. The HDS activity was much higher for the particles by dry comminution than for those by wet comminution.

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Change of acidity distribution of carboxyl groups in Loy Yang brown coal (LY) by heat-treatment was studied. For LY treated at 50℃, the distribution was separated into three components with mean pKa 3.8 (referred to as Peak A), pKa 5.5 (Peak B), and pKa 8.8 (Peak C), and Peak A and B were assigned to carboxyl groups. With increasing heat-treatment temperature, the amount of Peak A decreased gradually, while the large amount of Peak B decreased significantly. The mean pKa values of Peak A and B shifted to lower pKa region. From these results compared with pKa's of many carboxylic acids, it was estimated that dicarboxylic acid-like structure shifted to monocarboxylic acid-like structure by heat-treatment. In case of coexistence of calcium, the carboxyl groups of different acidity from the coal without calcium were decomposed during heat-treatment.

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The oxidation of brown coal loaded divalent cations mainly Zn^<2+> or Co^<2+> was performed using H_2O_2 aqueous solution under mild condition, and the influence of the divalent cations was studied on the oxidative products such as water soluble small molecule carboxylic acids. The yield of small molecule carboxylic acids from brown coal with pre-exchanged cations was higher than that from raw brown coal. Even at 30℃ the conversion of oxidation for 24h was over 70% due to coexisting CO^<2+>.

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Syngas adsorptions at 1.2MPa and room temperature on a precipitated cobalt catalyst reduced by H_2 and on that used for high-pressure FT synthesis were studied by diffuse reflectance FTIR spectroscopy. The syngas adsorption on the freshly reduced sample gives rise to two weak bands at 2013 and 2033cm^<-1>, which are assigned to linear adsorption of CO on fine metallic cobalt particles. Syngas adsorption on the sample used for FT synthesis gives rise to two strong bands at 1999 and 2021cm^<-1>, and several weak bands at 2150, 2025, 1897 and 1822cm^<-1>. The bands at 1999, 2021 and 1897cm^<-1> are assigned to CO adsorption on cobalt carbides; the bands at 2025 and 1822cm^<-1> may be associated with sintered metallic cobalt species and the band at 2150cm^<-1> due to Co^<2+> species.

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Dimethyl ether (DME) from coal via syngas attracts much attention as high quality diesel fuel of next generation. 90% single pass conversion should be attained at 2-3MPa for economic process from small scale carbon sources. Temperature gradient in reactor together with improved catalyst gives such high conversion. The temperature profile was optimized using genetic algorithm.

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An attempt to prepare resol-type phenol-formaldehyde resin from a coal tar-derived phenol oil, which was used as a model substance of acidic oil in coal liquefaction. The following conclusions were obtained. (1) The phenol oil could give resol resin by reacting with formaldehyde under a basic condition. Methyl group was successfully introduced into the polymer which was ascertained by FTIR. (2) The degradation temperature of the obtained resins were lower than a commercial resol-type phenol-formaldehyde resin, resulting in the emission of larger molecules during pyrolysis.

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Release behavior of sodium and potassium was followed during pyrolysis of coals in a nitrogen stream up to 1200℃. Sodium and potassium in coal and char were classified into five fraction by a serial dissolution method with H_2O, CH_3COONH_4, HCl, H_2SO_4 and HF solutions. Fraction of H_2O soluble and CH_3COONH_4 soluble decreased, and fraction of H_2SO_4 soluble increased with heat treatments for both alkali metals. Characteristic change was observed for the fraction of each solvent soluble depending on the kind of coal and pyrolysis condition.

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The extraction procedure of phenols in water solution was studied using liquid DME and n-butane. The procedure could be substituted for phenol extraction using toluene in a methanol-mediated extraction process. The extraction rates of phenol and m-cresol were 84 and 89%, respectively, using 1.5 times liquid DME as much as water in volume, and 91 and 96% by twice extraction, while n-butane was less effective. Based on the results, a conceptual flow diagram of closed extraction process was designed.

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