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Selectivity effects in aqueous supercritical fluid extraction of subbituminous coal

✍ Scribed by J.M.L. Penninger

Publisher
Elsevier Science
Year
1989
Tongue
English
Weight
776 KB
Volume
68
Category
Article
ISSN
0016-2361

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✦ Synopsis

Aqueous supercritical fluids at pressures of 7 to 10 MPa and temperatures from 350 to 500Β°C are effective media for the extraction of oils from coals. The most reactive coal macerals are exinite and resinite, and the oils formed have a high content of straight-chain paraffms. Vitrinite is converted only when carbon monoxide is present in the aqueous fluid; these oils consist primarily of aromatic and polar components and, in contrast to exinite derived material, contain only small quantities of paraffins. Micrinite and semi-fusinite are inert. Addition of Na,CO, to the fluid enhances vitrinite conversion markedly and also makes semi-fusinite more reactive. It is proposed that the formation of extractable material results from aqueous decarboxylation reactions of ester groups and from hydrolysis of ethers and sulphur-and nitrogen-functional groups. The hydrolysis reactions are considered to be enhanced by carbon monoxide as the result of increased ionic strength of the aqueous fluid due to formate and other CO/H,0 ionic interaction products.

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