Koichiro Kusunoki

Simultaneous desulphurization and demineralization of coal

Abstract Pulverized coals were treated in a molten bath of NaOH and KOH at 623 K. Over 90 wt% of the total sulphur and ash was removed in a 1 h reaction but the mass of the molten alkali had to be at least twice the mass of coal. To reduce the amount of alkali, a new reaction method was proposed. Coal particles were coated with alkali by being soaked in an aqueous alkali solution and dried in a vacuum oven, before being heated at 648 K in a nitrogen stream. When the amount of alkali exceeded 20–30 wt% of the initial coal weight, the removal of total sulphur and ash was increased and nearly equal to that obtained by the molten alkali bath method. The loss in gross heating value of coal treated by alkali impregnation was only 2.5 wt% after 2 h reaction at an alkali level of 43% of the initial coal weight.

ROLE OF HYDROGEN SPILLOVER IN A HYDROGENATION REACTION ON MONOMETALLIC (RU, RH, PD, OR PT) AND BIMETALLIC (RU-PD) CATALYSTS

The rates of benzene hydrogenation on Pl-, Pd-, Rh- and Ru-alumina (monometallic) catalysts and the adsorption of benzene, in the presence of hydrogen, were measured and a rate equation was derived based on these data. In a bimetallic catalyst, Ru-Pd-alumina, the rate of benzene hydrogenation on ruthenium was found to be enhanced due to the migration of spilled-over hydrogen from palladium to ruthenium.

Liquid mixing by large gas bubbles in bubble columns

Abstract Liquid mixing by large gas bubbles of spherical cup was investigated for co- and counter-current contact of air-water system with bubble columns of 5 and 10 cm dia. The results obtained are that for the column of 5 cm dia., the longitudinal dispersion coefficient ranges from 5 to 20 cm2/sec for superficial gas velocity from 0·07 to 8 cm/sec and that for the one of 10 cm in diameter it ranges from 9 to 45 cm2/sec for that from 0·035 to 8 cm/sec. Liquid mixing under the coexistence of large and small bubbles was also investigated and it was found that the gas holdup was fairly well explained by an equation derived on the assumption that the mixture of small bubbles and liquid behaves independently of large bubbles. The expansion model was applied to the experimental results on the longitudinal dispersion coefficient and it was observed that there should be the lower limit in the holdup of small bubbles where this model can be applied.

Anodic oxidation of coal slurries in flow-through packed bed electrodes

Abstract Experimental studies were made to determine the characteristics of anode systems depolarized by coal slurries. The anode was a packed bed of platinum-plated titanium pellets, through which the slurries were recirculated. This flow system increased collisions between coal particles and the anode surfaces so that the anodic oxidation of the coal was enhanced. At the same time, soluble organic compounds and Fe 2+ ions dissolved from the coal were oxidized at the anode, and Fe 3+ was reduced by thermochemical reactions with reducing compounds in the coal; this reduction was important in maintaining the current density in long-term electrolysis.

Kinetic investigations for hybrid process of water electrolysis and chemical coal desulphurization

Abstract Chemical coal desulphurization combined with water electrolysis has been systematically studied. Pyritic sulphur in pulverized coals was oxidized by Fe(III) ions to elemental sulphur and sulphate ions in an acidic solution. The removal of pyritic sulphur at 363–383 K in a solution of 0.89 M Fe(III) and l M HCl was about 100% for Illinois No. 6 coal and 87% for Miike coal. Fe(II) ions which were produced by the reaction between Fe(III) ions and coal slurries were utilized to depolarize the anode potential for the water electrolysis. The use of a three-dimensional electrode cell packed with graphite felt drastically increased the current density per unit feeder area to 1000 A m −2 at the cell voltage of 1 V. No deactivation of the graphite felt electrode was observed after the 20 h continuous electrolysis using the Illinois No. 6 coal filtrate. The energy consumption with respect to the hydrogen production was about half that of conventional electrolysis cells.

Continous production of free gluconic acid by Gluconobacter suboxydans IFO 3290 immobilized by adsorption on ceramic honeycomb monolith: effect of reactor configuration on further oxidation of gluconic acid to keto-gluconic acid

SummaryGluconobacter suboxydans IFO 3290 was immobilized by adsorption on ceramic honeycomb monolith, and continuous production of free gluconic acid from 100 g/l glucose was carried out in one- and three-stage monolith reactors. Further oxidation of gluconic acid to keto-gluconic acid by the immobilized cells has been found to be more suppressed in the three-stage monolith reactor. This finding can be explained by the fact that, with the three-stage reactor, the opportunity to oxidize gluconic acid further was decreased because the residence time of the reaction mixture at glucose conversion above the threshold value was shorter.

Kinetic study of coal slurry electrolysis-oxidation and desulfurization of Illinois No. 6 coal by aqueous ferric chloride

Abstract The kinetics of oxidation and desulfurization of Illinois No. 6 coal with a ferric chloride solution was extensively studied by monitoring the concentration-time profiles of Fe(II) and sulfate ions formation for the temperature range 333 to 363 K. The formation rates of both ions increased significantly with increasing temperature, and were independent of coal particle size. Increasing the initial concentration of Fe(III) ion caused an increase in the formation rates of both Fe(II) and sulfate ions, while addition of Fe(II) ion retarded the rates. A kinetic model was proposed assuming that coal matrix involves two different reactive sites which are oxidized consecutively. The rate expression derived in the Langmuir-Hinshelwood form provided excellent agreement with experimental results. Desulfurization kinetics were also modeled to fit the experimental data.

Measurements of Effective Diffusivities of Mercaptanes in Molecular Sieve 13 X

半径0.08cm, 長さ0.5～0.6cm の棒状のモレキュラーシーブ13X について, n-ヘキサンを溶媒とした時のエチル, ブチル,iso-ブチルおよびオクチルメルカプタンの0℃ における粒内有効拡散係数を, かきまぜ槽を用いて測定した。まず各系の平衡吸着量を,ついで外液濃度と接触時間の関係を測定した。得られた平衡関係はLangmuir型となり,この関係を拡散方程式に導入すると非線型の偏微分方程式が得られるが,その解法としてこれを数値的に解く方法を示した。これによって外液濃度の時間変化を算出することができる。この計算値が実測結果と一致するように有効拡散係数を選ぶことによって各系の有効拡散係数を求めた。その結果前述の各メルカプタンに対してそれぞれ5, 4, 3, および1.5×10-6[cm2/sec] の値を得た。

Experimental Studies on the Height of Dispersion Band in Settler for the System of Water-Kerosene

水-ケロシン系において水相分散の場合のセトラーにおける分散帯の厚みを測定した。実験に使用したミキサー・セトラーは共にガラス製で, セトラーは直径57mm長さ750mmのガラス円筒である。実測の結果分散帯の厚みは両相の見掛け流速の和の3.1乗, 分散相の供給比の4.9乗, 撹拌翼回転数の2.8乗に比例するという結果を得た。