Isamu Uemasu

Fundamental study of the effect of hydrogen donor solvent on coal liquefaction

Abstract To evaluate the hydrogen donating ability of solvent for coal liquefaction, the liquefactions of Taiheiyo coal (Japanese subbituminous coal) and Yallourn coal (Australian brown coal) have been carried out in a 500 ml autoclave at 430–450°C under high pressure of hydrogen or nitrogen using a red mud—sulfur catalyst in the presence of different kinds of hydrogen donor solvents such as tetralin, decalin, methyl substituted tetralins and naphthalenes, etc. Liquefactions of Taiheiyo coal and Yallourn coal using hydrogen donor solvents such as tetralin or methyl substituted tetralins showed higher conversion and yield of SRC than that obtained using decalin. On the other hand, to estimate the effect of the hydrogen donor solvent, ab initio SCF molecular orbital calculation for several solvent molecules, such as tetralin, decalin, naphthalene and their methyl substituted homologues, has been applied. Calculated reactivity indices, for example, frontier electron density of hydrogen atoms in the solvent molecule and atomic orbital bond population of CH bond, were discussed and compared with the experimental results.

Catalytic activity of oil-soluble molybdenum compounds for heavy oil hydrotreatment.

Catalytic activity of several oil-soluble molybdenum compounds was tested for upgrading low-quality heavy oil by high pressure thermalhydrotreatment.Reactions were performed by use of an autoclave of 300m1 capacity at temperature 470°C, reaction time 10min., initial hydrogen pressure 100kg/cm2 and stirring rate 1, 500ppm.Venezuela Morichal crude (S 4.19wt%, N 0.67wt%, V 463ppm, Ni 100ppm, C5-insoluble asphaltenes 17. 5wt%) was used as a feed.Molybdenumdithiophosphates, which are usually used as lubricant oil additives, were found to show high activity for sulfur and vanadium removal. Their activity was further enhanced by the addition of oil soluble cobalt compounds. The role of P and S in the activity enhancement for Mo catalysts was investigated with a variety of combinations of oil-soluble Mo, Co, P and S compounds. It was revealed that the addition of P compounds is essential for vanadium removal and the coexistence of P and S is effective for the removal both of sulfur and vanadium. Recycle use of the Mo-Co-P-S catalyst, which could be recovered as a solid matter, resulted in a gradual decline of activity. However, even after 3 to 4 recycle uses, its activity was still higher than the initial activity of conventional Co-Mo-Al2O3 catalyst.

Heavy Oil Hydrotreatment Using Dispersed Mo-based Catalyst. Effectiveness of Hydrogen Transfer Desulfurization with Tetralin.

The effectiveness of hydrogen transfer desulfurization (HTD) in heavy oil hydrotreatment was investigated using tetralin as a hydrogen donor solvent. Reactions were carried out at reaction temperatures 410 and 450& using a batch reactor with varying the initial hydrogen pressure.Three different catalysts, namely a highly active dispersed Mo-Co-P-S (I), another kind of dispersed Mo-Co-P-S which was severely poisoned by excess phosphorus (II) and CoMo/Al2O3, were utilized. Parallel experiments using decalin, a poor hydrogen donor, were also performed to compare with the results using tetralin.The results with the catalyst (I) revealed that at low hydrogen pressure the HTD did function effectively but at a higher pressure, i.e. at an initial hydrogen charge of 80kg/cm2 or higher, no advantageous effect of tetralin addition was observed. The effectiveness of HTD seemed to depend upon such catalyst functions as dissociative adsorption of molecular hydrogen and dehydrogenation of solvents.Both of the devanadization and the coke-forming reactions were largely affected by hydrogen pressure, and at 80kg/cm2 of initial charge the results of reactions with tetralin were almost the same as those with decalin, irrespective of the kind of catalyst used. This indicates the reaction sites for those reactions are different from the sites for desulfurization.