Patent GB-497089-A (GB)
Title: Improvements in the recovery of polynuclear compounds
IPC: C10G1/00
Filed: 1937-04-12
Abstract: In a process for recovering unitary polynuclear compounds from the products obtained by subjecting extraction products of coal to destructive hydrogenation, the destructive hydrogenation products are subjected to a distillation which is effected, at least in part, at a temperature of about 500 DEG  C. or above.  The destructive-hydrogenation products may be dehydrogenated before they are distilled.  As solvents for extracting the coal, use may be made of hydrogenated cyclic compounds, e.g. hydrogenated naphthalene or anthracene, preferably in admixture with phenol or tar fractions containing phenol; middle oils or heavy oils may also be used.  The extraction may be effected at 300-500 DEG  C., preferably at 350-475 DEG  C., under pressure and optionally in the presence of a small proportion of hydrogen and/or a catalyst, e.g. a compound of a metal of periodic groups 4-8, a halogen, a hydrogen halide, or a halide of a metalloid.  In the examples: (1) finely ground coal is heated to 400 DEG  C. under 100 atm. pressure with a mixture of tetrahydronaphthalene and cresol, and the product is filtered, mixed with a heavy oil from mineral coal, and distilled at 260 DEG  C., whereby tetrahydronaphthalene, cresol and naphthalene are removed; the distillation residue is then subjected to destructive hydrogenation at 450 DEG  C. and 600 atm. pressure in the presence of tin oxalate and ammonium chloride, and the product is freed from benzine and middle oil by distillation; the distillation residue is dehydrogenated at 520 DEG  C., the products are condensed, and the condensate is fractionally distilled under reduced pressure; (2) a coal extract prepared and distilled as in example 1 is subjected to destructive hydrogenation at 515 DEG  C. and 600 atm. pressure, and the products are led to a separator kept at 500 DEG  C. under the same pressure; the vapours from the separator are condensed and, after removal of benzine and middle oil, the condensate is fractionally distilled under reduced pressure.ALSO:In a process for recovering unitary polynuclear compounds from the products obtained by subjecting extraction products of coal to destructive hydrogenation, the destructive-hydrogenation products are subjected to a distillation which is effected, at least in part, at a temperature of about 500 DEG  C. or above, and polynuclear compounds are then recovered from the distillate by the methods ordinarily used in recovering polynuclear compounds from coal-tar fractions, or by the methods described in Specification 435,254. The destructive-hydrogenation products may be dehydrogenated before they are distilled.  As solvents for extracting the coal, use may be made of hydrogenated cyclic compounds, e.g. hydrogenated naphthalene or anthracene, preferably in admixture with phenol or tar fractions containing phenol; middle oils or heavy oils may also be used.  The extraction may be effected at 300-500 DEG  C., preferably at 350-475 DEG  C., under pressure and optionally in the presence of a small proportion of hydrogen and/or a catalyst, e.g. a compound of a metal of periodic groups 4-8, a halogen, a hydrogen halide, or a halide of a metalloid. In the examples: (1) finely ground coal is heated to 400 DEG  C. under 100 atm. pressure with a mixture of tetrahydronaphthalene and cresol, and the product is filtered, mixed with a heavy oil from mineral coal, and distilled at 260 DEG  C., whereby tetrahydronaphthalene, cresol and naphthalene are removed; the distillation residue is then subjected to destructive hydrogenation at 450 DEG  C. and 600 atm. pressure in the presence of tin oxalate and ammonium chloride, and the product is freed from benzine and middle oil by distillation; the distillation residue is dehydrogenated at 520 DEG  C., the products are condensed, and the condensate is fractionally distilled under reduced pressure to yield fractions from which carbazole, hydrogenated pyrenes, pyrene, and mono- and di-methyl pyrenes are recovered; further distillation is then effected with introduction of air into the distillation vessel, whereby the temperature is raised to about 500 DEG  C. and fractions from which benzoperylenes can be recovered, and a fraction containing sublimed coronene, are obtained; (2) a coal extract prepared and distilled as in example 1 is subjected to destructive hydrogenation at 515 DEG  C. and 600 atm. pressure, and the products are led to a separator kept at 500 DEG  C. under the same pressure; the vapours from the separator are condensed and, after removal of benzine and middle oil, the condensate is fractionally distilled under reduced pressure to yield fractions from which carbazole, pyrene, methylpyrenes, benzoperylene and coronene are recovered; the residue from the separator is distilled as described in example 1, optionally after dehydrogenation, to yield fractions from which polynuclear compounds are recovered.