The role of donatable hydrogen and gaseous hydrogen in the NEDOL process was investigated with a 51 batch-autoclave. The following conclusions are obtained. (1) Both donatable hydrogen in the recycle solvent of lt/d Process Support Unit (PSU) and gaseous hydrogen contribute to the coal liquefaction reaction. The donatable hydrogen is superior because it largely promotes liquid-phase reaction. (2) The hydrocracking reaction of the recycle solvent occures under coal liquefaction conditions, and gaseous hydrogen is transferred to the recycle solvent. (3) Severe conditions in the solvent hydrogenation reaction are needed in order to make use of hydrogen effectively and obtain high oil yield.
The hydrogenolysis reaction products derived from Muswellbrook coal were separated into dichloromethane insoluble (liquefaction residue ; CLR) and dichloromethane soluble (DS). DS was separated into non-basic fraction and basic (B) fraction. Then, the hydrogenolysis reactions of mixture of B and CLR were carried out at 420°C for lh under the presence of H2 (5.9MPa) with red mud and sulfur (RMS). Demineralized CLR (DAR) and the sulfided Co-Mo/Al2O3 catalyst (SCM) were also used for the hydrogenolysis. Effects of demineralization of CLR and the catalyst on the hydrogen transfer during the co-upgrading reactions of coal liquefaction residues with B were investigated as follows. During the co-upgrading reactions of mixture of B and CLR or DAR, it was considered that CLR or DAR was dissolved and dispersed into B composed of nitrogen heterocyclic compounds. Under the presence of SCM, the upgrading of hexane insolubledichloromethane soluble in the mixture was not enhanced, but the upgrading of dichloromethane insoluble (DI) in the mixture was observed. The preferential adsorption of DI onto the surface of SCM occurs because DI is composed of highly condensed basic aromatic compounds. During the co-upgrading reaction of mixture of B and CLR with RMS, minerals in CLR were also sulfided by the added sulfur. The synergistic effects on co-upgrading of mixture of B and CLR appeared since more hydrogens were transferred to the mixture owing to the catalytic effects of the sulfided minerals. However, in the reaction of mixture of B and DAR with RMS, no effect on the co-upgrading was observed due to low mineral content in DAR.
The hydro-upgrading reactivity of the vacuum residue produced in PSU 1 t/day plant for Wandoan coal was examined, using commercial NiMo/γ-Al2O3 catalysts in relation to the structure of its asphaltene, to find a way for the complete conversion of the coal to oil. The asphaltene content in the original residue was reduced to 5% on d.a.f. coal base under conditions, 450°C, 15MPa H2, 60min, 1.5 solvent/residue ratio, and solvent composition of 75% 1, 2, 3, 10b-tetrahydrofluoranthene 4HFL and 25% pyrene. Such conditions removed completely the preasphaltene, while 17% of organic residue remained. Hydrogen donor 4HFL and aromatic hydrogen-shuttler pyrene were effective to convert residual asphaltene and preasphaltene. The catalyst of large pore was suitable for the conversion of preasphaltene while the conversion of asphaltene requires hydrocracking activity. Brown & Ladner parameters of the asphaltene before and after the hydrotreatment were calculated based on elemental analyses, 1H and 13C-NMR, VPO and GPC. Although the molecular weight of the asphaltene stayed around 600, the degree of aromaticity and condensation increased after the hydrotreatment. The conversion of asphaltene to oil is suggested to require reduction of molecular weight while the remaining asphaltene suffers the dehydrogenation, dealkylation and some condensation reactions. The origin of inert asphaltene is briefly discussed.