Masato Kouzu

Catalytic activity of iron compounds for coal liquefaction

Abstract The catalytic activity of pyrite and synthesized α-FeOOH in coal liquefaction was investigated using batch autoclaves with the aim of developing an industrial iron catalyst. The results indicate that the presence of H 2 S helps gaseous hydrogen transferring and prevents deactivation so that the catalyst promotes hydrocracking of coal and hydrogenation of the products. The activity converges with excess H 2 S and sulfur addition equivalent to an S/Fe molar ratio of 2.0 being reasonable for the activation. The active site is located on the outer surface, with finely divided catalysts exhibiting high activity. Both pulverized pyrite and synthesized α-FeOOH are sufficiently fine as to exhibit high activity in the process. Pulverized pyrite is an industrially feasible iron catalyst for coal liquefaction process, because it is inexpensive and does not require sulfur addition.

Effect of solvent hydrotreatment on product yield in the coal liquefaction process

Abstract Effects of solvent hydrotreatment on product yields in the NEDOL coal liquefaction process were examined based on the data obtained by a 150 t/d pilot plant operation. When the hydrogen gas consumption in the liquefaction stage was kept constant at 4.7 wt.%-daf (wt.% on the basis of dry and ash-free coal), the yield of the oil fraction increased from 51.0 to 54.9 wt.%-daf with an increase in the hydrogen gas consumption from 0.7 to 1.3 wt.%-daf in the hydrotreatment stage. In the hydrotreatment stage, about 30% of the hydrogen consumed was utilized for enrichment of naphthenic hydrogen content in the solvent, and the rest was used for both the removal of nitrogen from the solvent and the production of the light oil fraction. In the liquefaction stage, the hydrogen donated from the solvent was more efficiently utilized than the gaseous hydrogen for the production of the oil fraction. Under the conditions that the total hydrogen consumption in the hydrotreatment and liquefaction stages was kept constant, the yield of oil fraction and the nitrogen content in oil fraction were higher when the hydrogen consumption in the liquefaction stage increased with concomitant decrease in the hydrotreatment stage.

Deactivation of catalyst for solvent hydrotreatment in a coal liquefaction process

Contamination and a degree of deactivation of Ni–Mo/γ-Al2O3 catalyst used for solvent hydrotreatment in a coal liquefaction process were examined based on the data obtained from a 150 ton/day pilot plant. When solvent hydrotreatment was carried out at 300°C, the Fe, Ca, and Si contents of the catalyst used for 3200 h were higher than those for 500 h. The Fe contaminant tended to be greatly concentrated near the edge of the catalyst grain. Pore volumes of the catalysts used for 3200 and 500 h were 0.34 and 0.39 ml/g, respectively. The catalyst used at 325°C for 2800 h contained more Fe than that at 300°C for 3200 h. No difference in carbon content was obvious among the three used catalysts. In the down-flow fixed bed hydrotreater, Fe content was larger while the pore volume was less upstairs. In solvent hydrotreatment at 300°C, the degree of deactivation was 20% after 3200 h. When solvent hydrotreatment was carried out at 325°C, the degree of deactivation reached 25% after 2800 h. The amount of contaminants are compared in relation to the degree of deactivation, and mechanisms on catalyst deactivation in the solvent hydrotreatment are discussed.

Function of Hydrogenated Solvent in the Coal Liquefaction System.

The influence of heavy distillate in the solvent for coal liquefaction was investigated with a 5L batch-autoclave.The following conclusions are obtained.(1) Heavy distillate in the solvent consumes much hydrogen and prevents hydrogen translation on asphaltene hydrogenating reaction. Consequently, it reduces oil yield in the coal liquefaction system.(2) Donatable hydrogen in the heavy solvent equally promotes coal liquefaction reaction to that in the recycle solvent. Severe hydrotreatment of the heavy solvent increases its hydrogen donatability and oil yield in the coal liquefaction system.