Studies on the Liquefaction of Coal (I)

Pyrolysis and Hydrocracking of Decalins, Tetralin, and 1-Methylnaphthalene as Coal Model Compounds

Abstract

Pyrolysis and hydrocracking of decalins, tetralin, and 1-methylna-phthalene as coal model compounds were studied to investigate the reaction mechanism in liquefaction of coal under initial hydrogen pressure of 0-50kg/cm² at350-470°C for 1-13
hr. Tetralin was the most unstable for thermal treatment, and converted to methylindans and to naphthalene plus decalins with nearly equal rate. A part of decalins and 1-methylnaphthalene reacted, but were relatively stable. When sulfur was added to these reaction system, dehydrogenation of decalins and tetralin was found to proceed stoichiometrically, and cis-/trans- isomerization of decalins was promoted remarkably. Demethylation and oligomerization of 1-methylnaphthalene were promoted in a similar nanner. Addition of phenolic compound depressed isomerization and disproportionation of tetralin. On hydrotreatment in the presence of Pd/carbon and Co-Mo/Al₂O₃ catalysts, dehydrogenation, demethylation and hydrogenation of aromatic ring were promoted. On the reaction over Fe/Si0₂-Al₂0₃ catalysts, decalins were hydrocracked to yield C₃-C₆ paraffins readily, tetralin underwent C-C bond scission and skeletal isomerization of naphthenic ring and alkylation. Methyl group migration of 1-methylnaphthalene to 2-methylnaphthalene arose overwhelmingly.