Patent GB-510736-A (GB)
Title: Improvements in the recovery of coronene
IPC: C07C15/20
Filed: 1938-03-02
Abstract: 510,736. Destructive hydrogenation ; oils. I.G. FARBENINDUSTRIE AKT.-GES., and JOHNSON, G. W. March 2, 1938, No. 6592. Addition to 435.254. [Classes 32 and 91] [Also in Group IV] Coronene is obtained by a process wherein coal-tar pitch is subjected to catalytic destructive hydrogenation, the high-boiling portion of the product, e.g., the portion boiling above 350‹C., is freed from solids, the solid-free residue is treated in known manner to separate asphalts, the asphalts are subjected to dry distillation or extraction with an organic solvent, and coronene is isolated from the distillate or the extract. The destructive hydrogenation of the coal-tar pitch is preferably effected under energetic conditions,suitably at a temperature above 440‹C. under a pressure of 200-1,000, preferably 500-700, atm., in the presence of a catalyst comprising one or more metals of the fourth, fifth or sixth periodic group or compounds thereof ; the catalysts may be applied to carriers, or used together with halogen compounds. The removal of solids from the high-boiling portion of the destructive hydrogenation products may be effected by filtration or centrifuging, preferably after addition of benzene or other aromatic hydrocarbon. From the solid-free residue, preferably after distillation of the benzene or other aromatic hydrocarbon, the asphalts may be precipitated by addition of benzine or similar hydrocarbon of high hydrogen content, preferably at a raised temperature ; alternatively, liquefied normally gaseous hydrocarbons, such as propane or butane, may be added, or the asphalts may be separated with the aid of an adsorbent. The dry distillation of the asphalts may be effected with the aid of a gas or vapour and (or) in vacuo ; suitable gases or vapours are nitrogen, hydrogen, gases obtained in the dry distillation, carbon dioxide and steam. 'Alternatively, the asphalts may be extracted with a solvent such as an aromatic nitro compound or amine, a phenol, a higher alcohol such as propyl or amyl alcohol, or a higher aromatic hydrocarbon or a heterocyclic compound such as pyridine or quinoline. As a further alternative, the asphalts may first be extracted with a solvent and the residue then subjected to dry distillation. In the example, (1) coal-tar pitch is mixed with a heavy oil, obtained in the process, and the mixture is hydrogenated at 495‹C. and 650 atm. in the presence of lignite coke impregnated with ammonium molybdate; the products pass to a separator kept at 440‹C, and the high-boiling products withdrawn from the separator are diluted with benzene and filtered ; the filtrate is freed from benzene by distillation, and the distillation residue is poured into boiling benzine ; the precipitated asphalts are drydistilled in a current of nitrogen, and coronene is recovered, by recrystallization from aniline, from the yellow sublimate so obtained ; the residual oil from the precipitation of the asphalts is mixed'with another batch of coal-tar pitch ; (2) asphalts separated as in example 1 are extracted with ethyl alcohol and the residue is extracted with amyl alcohol; the second extract contains coronene.