The research done by author for 40 years has been reviewed. Since 1954, the author has initiated his research on coal science at Resources Research Institute, Agency of Industrial Science and Technology. He has shifted to Hokkaido University in 1975 in order to establish new laboratory of Coal Research Institute. The research areas are described below and will be concerned in detail: (i) Coal as a molecular solid, (ii) Carbonization, liquefaction of coal, (iii) Carbonaceous mesophase and carbons from pitch and heavy oil.

View full abstract

Sorption phenomena of methanol on coal was investigated by repeated sorption and desorption technique using oxidized Taiheiyo coal. Rate of methanol sorption was increased by repeated sorption and desorption. This rate increase occurred drastically after the first run. Time of methanol sorption in the first run scarcely affected the rate, however, final vapor pressure in the first run was proved to be essential for the increase in rate.

View full abstract

In order to investigate the bonding interactions in the cross-linking structure of coal, several Simulation experiments were carried out by using synthetic polymers. It was found that the solvent swelling behaviors of coal were more resemble to those of an elastomer (Styrene-ethylene/Butylene block co-polymer, Asahi-Kasei Co.) than a cross-linked polymer (styrene-divinylbenzene co-polymer, Biolad Lab. Co).

View full abstract

The effect of chemical demineralization on solvent extraction characterization of coals was investigated from the pyridine or chloroform extractabilities and the changes of yield for each molecular weight distribution of the extracts. It was suggested that the non-covalent interactions in the coal structure were affected by the temperatures and concentrations in the hydrofluoric acid treatment.

View full abstract

In coal liquefaction, it is important to make clear the interactions of coal with solvent, such as solubilization and swelling. In this study, a flow microcalorimeter was utilized to measure heat of adsorption occured as the solvents flowed on the surface of coal. On the basis of heats measured and FTIR spectral measurement, the interactions of coal surface with solvent were examined. In this research, eight kinds of coal were used as samples, n-hexane as carrier liquid, methanol as polar solvent and THF, tetralin as non-polar solvent. It can be concluded that swelling of coal depends on adsorption behaviour of solvent and swelling ratio of coal can be estimated based on the heat of adsorption.

View full abstract

The change in inter- and intra-molecular interaction in coal with electron acceptor has been investigated by means of EPR and ^1H-NMR spectroscopy. The EPR spectra of high rank coal were simulated in terms of two component signals, one broad and one narrow. The intensity of broad signal enhanced with increase in the amount of iodine doped in coal. The intensity of narrow signal, however, did not change with increase in the amount of iodine. The spin-lattice relaxation time T_1 decreased with increase in the amount of iodine. These facts indicate that the iodine doped in high rank coal modified the inter- and intra-molecular interaction system in coal.

View full abstract

Mechanism for coal solubilization with butylzinc compounds and alkyl halides, which are active species of zinc/alkyl halide system, was investigated through the alkylation of Yubari coal and coal model compounds using both BuZnI/Bu_2Zn/BuI and Bu_2Zn/BuI systems. In BuZnI/Bu_2Zn/BuI system, an addition reaction of butyl groups to aromatic moieties of coal structure prevails than a substitution reaction, and the former reaction was found to be more effective in increasing the solibilities of coal in a solvent than the latter.

View full abstract

Trifluoromethane sulphonic acid was found to desulphurize coal in the presence of hydrocarbon without hydrogen gas at as low as 150-200℃ for 3h under autogeneous pressure of 2.6-6.6MPa. No solvent or isopentane provided lower desulphurization of 19.8 or 23.4%, respectively, while toluene did 48.7% desulphurization.

View full abstract

In the presence of co-catalyst such as imidazole, a brown coal was solubilized by immobilized iron porphyrin catalyst for monooxygenase model and hydrogen peroxide. The polar materials increased in the solubles during coal solubilization, however, it was not due to marked incorporation of carboxyl functions into coal structure. The effect of catalyst on coal solubilization was discussed based on the oxidation reactions of various aromatic compounds.

View full abstract

The dynamic behavior of surface oxygen complexes formed during the gasification of carbon with isotopically labeled oxygen has been studied by transient kinetics. The surface oxygen complexes after the gasification were analyzed with temperature programmed desorption. A mechanism has been proposed from the present study, together with our former study on chemical form of surface complexes. It is proved that combination of techniques, such as TPD, TK, DRIFT and isotope labeling could be a powerful means to clarify the mechanism of carbon gasification with oxygen.

View full abstract

Flying slag particles have a tendency to deposit themselves on walls of the gasifier's exit and on tube surfaces of the syngas cooler, then sinter in the course of entrained coal gasification. Sintering behavior was examined using water quenched slag and char obtained by the pilot plant of HYCOL. The sintering temperature of the slag was approximately 800℃. The presence of carbon in the slag hindered the progress of sintering. When the concentration of carbon in the slag was above 4%, the slag did not sinter at 900℃. SEM analysis showed that the carbon in the slag acted as a dispersant.

View full abstract

The adhesion and the deposition behavior of coal ash on the gasifier wall were studies by the laboratory scale apparatus equipped with the wall temperature (T_w) control device. The ash melting temperature (T_M) and the sintering temperature (T_s) seemed to influence the adhesion force and the deposit form considerably. When T_w was below T_s, the deposit was "powder-ash" with very week adhesion. Between T_M and T_s, the deposit was "sintered-lump" with strong adhesion. Nealy T_M, "solid-slag" was formed. It could be detached by mechanical action.

View full abstract

A long run HYCOL gasification results were dissuced and analized by the use of the data-base for coal gasification accumulated in our Institute on the ratio of carbon conversion, on the cold efficiency and on the ratio of coal and oxygen.

View full abstract

Iron-loaded oak bark chars were prepared at 500℃-carbonization after cell wall swelling and demineralization as the pretreatments, and their hydrogasification reactivities were measured in a thermobalance. For swelling the cell wall structure, raw bark was soaked in boiling water or extracted in water with supercritical carbon dioxide. Demineralization was carried out by washing with 0.1N-HCl. Either swelling was beneficial for improvement in the dispersity of iron metal particles on char, by which iron raised the catalytic activity in the hydrogasificasion. Demineralization followed by each swelling was more effective to enhance the gasification reactivity. This is because finer particles of metallic iron could be produced by diminished interaction with ash components.

View full abstract

Hydrous mild pyrolysis (200℃, 50hr) residues of cellulose and redpine were hydrogenated at 350℃ in tetralin over a presulfided Ni-Mo/Al_2O_3 catalyst, and the products were compared with those of Morwell brown coal and Morwell coalified log.

View full abstract

A coal briquette was prepared by physical mixing of coal and limestone as a countermeasure for sulfurous acid gas emission from small scale boiler, and domestic oven. The effects of Ca/S molar ratio and furnace temperature on the behavior of the emission were investigated. To understand the behavior, temperature variation in the center of the briquette with time of combustion was measured and the relation among the combustion characterization, the highest temperature in the briquette, and the desulfurization perfarmance was discussed.

View full abstract

Model compounds including phenanthrene, anthracene, and dibenzothiophene were hydroprocessed in the presence of petroleum solvent and NiMo/Al_2O_3 catalyst in syngas-water systems. Significant water-gas shift reaction occurred simultaneously, and the hydrogen produced by the CO-shift conversion was utilized in the hydrogenation reactions.

View full abstract

Cracking of dinaphthylethane in 9,10-dihydrophenanthrene and diphenylethane in tetralin in the absence or in the presence of dispersed catalysts such as Mo-S and Ru was studied under hydrogen atmosphere. The amounts of hydrogen transferred from a gas phase and a donor solvent were determined and the amounts of hydrogen required to stabilize free radicals derived from the model compound were estimated from the products distributions. Most of the hydrogen required to stabilize free radicals seemed to come from the hydrogen donor solvent, even in the presence of an active catalyst.

View full abstract

The role of solvent in coal liquefaction has been studied about next four reactions; (1) rapid thermal cracking of unstable bonds, (2) slow cracking of rather stable bonds, (3) secondary cracking of cracked oil and (4) cracking of stable bonds followed by radical transfer.

View full abstract

Asphaltene equivalents of coal liquefaction residues (CLR) acted as good hydrogen donors in the hydrogenolysis of trans-stilbene, transferring their inherent hydrogens and regenerating solvent. There was no apparent correlation between the structural parameters of the CLR's and their hydrogen-donating abilities.

View full abstract

Effects of reaction time, temperature and pressure on the liquefaction reaction of Victorian brown coal in the presence of iron/sulfur catalyst were discussed from the viewpoint of the hydrogen transfer. The amount of transferred hydrogen from both solvent and H_2 to total products (H(t)) represented the progress of the liquefaction reaction. The transferred hydrogen from the solvent played important role under the conditions of lower H_2 pressure and shorter time. The optimum condition was found for the efficiency of hydrogen consumption by means of distillate yield/H(t) ratio because C_1-C_4 gas markedly increased at higher temperature. This condition depended on the hydrogen donor ability of the solvent.

View full abstract

The influence of heavy distillate in the recycle solvent in the coal liquefaction process was investigated with a 51 batch-autoclave. The following conclusions are obtained (1) Concentrating in heavy distillate in the recycle solvent causes an inhibition of the coal liquefaction reaction and the solvent hydrogenation reaction. (2) Increase of gas/slurry ratio in the coal liquefaction reaction and sever condition in the solvent hydrogenation reaction are effective countermeasures on the occasion of concentrating in heavy distillate in the recycle solvent.

View full abstract

The hydrogenolysis reaction of model compounds was discussed in the presence of synthetic pyrite as catalyst under 3MPa of initial hydrogen pressure at 350〜500℃ for 15min. Synthetic pyrite accelerated the cleavage of bridged C-O bond of dibenzyl ether. On the other hand, the C-O bond of diphenyl ether and hetero cyclic C-O bond was not cleaved at the reaction temperature lower than 450℃. Aliphatic C-C bonds of phenylcyclohexane also was not splitted with synthetic pyrite catalyst in this reaction condition.

View full abstract

Effects of oxidation of synthetic pyrite FeS_2 catalyst under air on the hydrogenation of 1-methylnaphthalene were investigated under coal hydroliquefaction condition. Catalytic activity of FeS_2 catalyst was decreased by the increasing of storage time under air at room temperature. The deactivation rate of FeS_2 was enhanced by the raising of atmospheric temperature. It was proved that the deactivated pyrite catalysts with air oxidation was reactivated by enough sulfur addition to the reaction system.

View full abstract

Ketjen-Black(KB), which has extremely high surface area and low specific gravity, was selected as a catalyst support to prepare a highly dispersed NiMo catalyst with the function for recovery as well as higher activity for hydrogenation and coal liquefaction. The hydrogenation activity of KB-supported NiMo catalysts was improved by designing the supports, preparation methods, metal salts species. The best KB-supported NiMo catalyst exhibited about four times higher hydrogenation activity (ca.85%) than a commercial Ni-Mo/Al_2O_3 catalyst.

View full abstract

Coal pretreatments were investigated in order to accelerate the depolymerization of coal macromolecules and to facilitate the catalyst recovery. Wyoming coal was activated by the mild preptreatment with 10% CH_3COOH aq. at room temperature for 24hr, the oil yield increasing to 45% with the decreased yields of the heavier products. The mild pretreatment also facilitated the recovery of a ferromagnetic Fe_3Al catalyst, decreasing the deposit amount on the catalyst.

View full abstract

Hydrogenolysis reactions of mixture of coal liquid and coal liquefaction residue were carried out using red mud-sulfur or Co-Mo/Al_2O_3 catalyst. The effect of deashing treatment of coal liquefaction residue were also investigated. Notable synergistic effects such as the increase of n-hexane soluble and the decrease of dichloromethane insoluble were observed only the hydrogenolysis of basic fraction of coal liquid and nondeashed coal liquefaction residue using red mud-sulfur catalyst.

View full abstract

The activity of synthetic iron oxyhydroxide catalysts for a brown coal liquefaction was investigated. γ-Iron oxyhydroxide catalysts finely divided in a coal-liquefied solvent gave much higher oil yields compared to other iron-based catalysts. The high activity was considered to be because synthetic γ-iron oxyhydroxides consisted of fine primary particles and because they highly dispersed in a reaction medium that is a coal-liquefied solvent.

View full abstract

Catalytic activity of purverized pyrite was investigated in relation to its physical and chemical properties. The following conclusions are obtained; (1) Catalytic activity of pyrite increases with the dispersion of particles and the number of active-site in the coal liquefaction reaction system. (2) Catalytic activity of pyrite is infered to depend on the rate of formation of pyrrhotite in the coal liquefaction reaction system.

View full abstract

In the operation of coal liquefaction unit, the deposits are formed and accumulated at the bottom in the coal liquefaction reactors. The deposits were observed with Polarized Optical Microscope and Scanning Electron Microscope. Then, elemental distribution was analyzed by EDX on the same point of view at SEM-observation. It is found that the core of deposits have some kinds of elements and the growing process of double structure varies with the element of core.

View full abstract

Thermal treatment decomposing carboxylic groups of brown coal in the process solvent is effective to suppress the formation of carbonate scale in the latter liquefaction section. The process reliability is expected to be further improved with that pretreatment. The influence of pretreatment temperature and solvent species to liquefaction yield is studied in this paper.

View full abstract

In BCL Process, CLB (coal liquid bottom, b.p.>420℃) recycle and increase in gas/slurry ratio by gas recycle are very effective to increase the oil yield. In order to investigate their mechanisms and establish more suitable their recycle conditions, BSU (Bench Scale Unit) was remodeled to recycle CLB continuously and change the route to various reaction stages. In this paper, CLB recycle, gas recycle and their combined effects with new functions are reported.

View full abstract

Hydrothermal-treatment was applied to Victorian brwn coal as pretreatment of liquefaction. This treatment removes metal carboxylates in the coal which cause scale troubles during the liquefaction. High temperature treatment resulted in decreasing reactivity of the coal Liquefaction. It is preferable that hydrothermal treatment is carried out about 300℃ to maintain the reactivity of the coal liquefaction.

View full abstract

A two stage upgrading process, consisting of hydrogenation of armatic rings and hydrocracking of reduced aromatics was proposed for producing light fractions from the middle and heavey coal-derived distillates. In this work, optimizations of catalyst support, and metal species of hydrocracking catalysts were performed in order to design new catalysts for second stage upgrading. The following results were obtained; 1) Zeolite gave much higher hydrocracking activity than alumina and other double oxides. 2) The order of hydrocracking activity of metal species was Ni-W>Ni-Mo>Co-Mo. 3) USY zeolite showed much higher hydrocracking activity among various zeolites tested.

View full abstract

Pyrolytic behaviour of benzyl-substitued naphthalenes, phenanthrenes, and fluorenes as coal model compounds has been investigated. It has been found that the position of the benzyl-substituent on the polyaromatic compounds is a marked function in determining the composition of the pyrolysis products.

View full abstract

The iron catalyst promotes more efficiently the nitrogen removal of brown coal during inert pyrolysis. The Fe 2p3/2 XPS spectra show that the iron on brown coal char is more highly dispersed and in closer contact with the char substrate. The N 1s spectra suggest that pyrrolic nitrogen can be removed readily, compared with pyridinic nitrogen. The mechanism of the present nitrogen removal is discussed in terms of iron dissolution in the char phase and subsequent formation of interstitial iron nitrides.

View full abstract

The decomposition behavior of coal nitrogen functionality during pressurized rapid pyrolysis was investigated at temperature of 765-1215℃ to elucidate the mechanisms of NO_x formation in pressurized fluidized bed combustion. X-ray photoelectron spectroscopy technique was used to determine of nitrogen forms of the parent coal and the char after pyrolysis. Under pressurized condition, the yield of volatile nitrogen and the decomposition fractions of pyrrolic and pyridinic nitrogen form were increased with increasing pyrolysis temperature and pressure.

View full abstract

Taiheiyo, Akabira and Miike Coal pulverized under 100mesh or 24-42 mesh were degradeted thermally using a free fall reactor at the temperature from 450℃ to 800℃. H/C of produced char was measured by the ultimate analysis and the amount of THE solubles remained in the produced char was measured by the extraction. Produced char was also observed by SEM. These experimental results showed clearly that Taiheiyo Coal melted only at the surface, and that THE solubles in the char from Taiheiyo Coal were not so much as those in the chars from Akabira and Miike Coal which melted like ball and stuck together.

View full abstract

A brown coal was swollen in vapor of polar organic solvents highly pressurized to 2-7MPa at 220-280℃ for 1h, and was instantaneously released with the solvent vapor into an evacuated chamber at ambient temperature. Rapid and adiabatic expansion of solvent vapor exploded and quenched the coal. The original and exploded coals were subjected to flash pyrolysis at 764℃ in He or N_2 by using a Curie-point pyrolyzer. The explosion treatment with methanol drastically increased tar yield from 18wt% to 33wt%, while it decreased the yeilds of char and inorganic gases (H_2, CO, CO_2 and H_2O). FT-i.r. analysis revealed that the explosion treatment patially broke hydrogen bondings and caused O-methylation between methanol and coal OH, both of which degraded macromolecular network of the coal and suppressed the cross-linking among OH groups.

View full abstract

Taiheiyo coal mixed with various kinds of alkaline hydroxides was heated up to 850℃ under a flow of argon for obtaining the activated carbon with high surface area and fuel gases. By the addition of each alkaline hydroxide, tar and gas produced were decreased and increased, respectively. The amounts of hydrogen, methane and carbon monoxde evolved were increased with increasing the additives. The resulting char had a high surface area and a large adsorption capacity for benzene vapor at 20℃ and metylene blue in an aqueous solution. CsOH was found to be the most effective addition for preparation of the high-quality activated carbon.

View full abstract

The four kinds of coal samples, Wandoan, Datong, Taiheiyo and Mequinenza, were treated by nitric acid and the inorganic sulfur compounds in coal were eliminated. The amount of hydrogen sulfide liberated from coals with nitric acid treatment during the pyrolysis in hydrogen flow were increased in comparison with raw coals and its liberation curves plotted against temperature were also changed. It was suggested from <13>^C-NMR and FT-IR measurement of raw and treated coal samples that the oxidation of coals by nitric acid treatment was not remarkable, while the amounts of aliphatic carbons in treated coals were slightly decreased.

View full abstract

Co-pyrolysis of coal and shale oil atmospheric residues were performed and the structural changes during the co-pyrolysis were investigated by using solid state ^<13>C-NMR spectra. The effect of coal species. shale oil species and the heating rate were also studied. The results indicated that the condensation reaction was depressed and the reactivity increased with the amount of transferable hydrogen of oil shale and the heating rate.

View full abstract

In order to minimize the energy consumption of drying process at coal conversion systems the mechanism of retention of water molecule on coal was studied. The ratio of the number of water molcules absorbed as moiture to that of O and N atoms which were presumed to provide the adsorption site on coal was investigated on various kind of coals and their chars. In the case of bitumonouse coals and anthrasctes, the ratio was ranged from 0.20 to 0.25, but it increased with the number of O and N atoms for lignites and subbituminouse coals.

View full abstract

The factors that determine the easiness of disintegration of brown coal briquttes by sorption of water was investigated by employing some surface treatment toward brown coal particles, steam treatment, acid washing, Ca-exchange, and heat treatment. Increase in COOH brought by steam treatment rather than decrease in cation by acid washing was found to show an excellent resistance against the disintegration. Heat treatment at 200℃ was optimum by giving a good resistance comparable to steam treatment.

View full abstract

The ignition temperature of the six different rank coals was measured for understanding the oxidization behavior. As a result, we have found correlation between ignition temperature and activation energy for suaface oxidation. It seemed that maceral group or ash content affect oxidization about low lank coal.

View full abstract