GB493447A - Improvements in the recovery or production of unitary cyclic compounds from the products obtained in the pressure extraction of solid carbonaceous materials - Google Patents

Abstract

Unitary cyclic compounds, e.g. benzene, toluene and higher homologues, pyrene, methylated pyrenes, chrysene, anthracene, are obtained from the extracts produced in the pressure extraction of solid carbonaceous materials with solvents by cracking the extracts at elevated temperatures and recovering the unitary cyclic compounds from the products by physical or chemical methods. Solvents for the extraction process comprise middle or heavy oils, phenols, and wholly or partly hydrogenated naphthalene, anthracene, phenanthrene or other polynuclear compounds or mixtures thereof. The extraction is carried out at 200-500 DEG C. and under pressures up to 1000 atmos. The initial material may be pretreated, e.g. by neutralization with dilute acids; by treatment with gases or vapours, e.g. nitric oxide, oxygen, halogen or halogen halide; by preheating; or by addition of catalysts, e.g. spraying with metal salt solutions in water or organic solvents. The cracking is carried out at temperatures of 450-750 DEG C. if desired under pressure and in presence of gases, e.g. steam, hydrogen, nitrogen, oxides of carbon, but hydrogen should not be present under conditions leading to hydrogenation, i.e. at temperatures below 550 DEG C. the hydrogen partial pressure should be less than 10 atmos. and above 550 DEG C. from 20-50 atmos. The cracking may be carried out in cracking apparatus or in low - temperature carbonization retorts and in presence of catalysts, e.g. oxides, halides, phosphates, or sulphides of metals of groups IV - VIII; silicious material pretreated with acids or gases. The extract is preferably divided into fractions before cracking by distillation or treatment with solvents, e.g. benzenes or benzines, sulphur dioxide, phenols, liquid ammonia, aniline, nitrobenzene, furfurol, phenyl hydrazine, glycol derivatives, fumaric acid, keto-acids, or liquefied normally-gaseous hydrocarbons or mixtures of the above solvents. The extracts may be subjected to dehydrogenation before or after the cracking treatment, e.g. at 400-700 DEG C., in presence of gases or vapours and under such conditions that hydrogen merely is split off. The dehydrogenation and the cracking may be carried out in the same chamber. Other methods of dehydrogenation comprises treatment with air or oxygen in presence of copper at 350 DEG C.; by heating with sulphur at 150-300 DEG C.; by treatment in presence of catalysts, e.g. those that bind hydrogen, e.g. selenium, tellurium, oxides of nitrogen, dilute nitric acid; by halogenation. Prior to the recovery of the unitary compounds the products may be refined to remove wax or polymerization products by treatment with solvents. Mineral coal is extracted at 410 DEG C. with a mixture of tetrahydronaphthalene and cresol and the extract is cracked in a low-temperature carbonization retort at 600 DEG C. The vapours formed are dehydrogenated by passage for three seconds over active carbon impregnated with molybdenum and cobalt sulphides. The products obtained below 180 DEG C. comprise mainly benzene, toluene and higher homologues while from the fractions of higher boiling point acenaphthalene, fluorene, anthracene, pyrene and its methyl derivatives and chrysene are separated by fractional crystallization. Specification 435,254 is referred to.ALSO:Unitary cyclic compounds, e.g. benzene, toluene and higher homologues, pyrene, methylated pyrenes, chrysene, anthracene, are obtained from the extracts produced in the pressure extraction of solid carbonaceous materials with solvents by subjecting the extracts to thermal treatment, e.g. cracking at elevated temperatures and recovering the unitary cyclic compounds from the products by physical or chemical methods. Solvents for the extraction process comprise middle or heavy oils, phenols, and wholly or partly hydrogenated naphthalene, anthracene, phenanthrene or other polynuclear compounds or mixtures thereof. The extraction is carried out at 200-500 DEG C. and under pressures up to 1000 atmos. The initial material may be pretreated, e.g. by neutralization with dilute acids, by treatment with gases or vapours, e.g. nitric oxide, oxygen, halogen or halogen halide, by preheating, or by addition of catalysts, e.g. spraying with metal salts solutions in water or organic solvents. The thermal treatment is carried out at temperatures of 450-750 DEG C., if desired under pressure and in presence of gases, e.g. steam, p hydrogen, nitrogen, oxides of carbon, but hydrogen should not be present under conditions leading to hydrogenation, i.e. at temps. below 550 DEG C. the hydrogen partial pressure should be less than 10 atmos. and above 550 DEG C. from 20-50 atmos. The thermal treatment may be carried out in cracking apparatus or in low-temperature carbonization retorts and in the presence of catalysts. The extract is preferably divided into fractions before cracking by distillation or treatment with solvents, e.g. benzenes or benzines, sulphur dioxide, phenols, liquid ammonia, aniline, nitrobenzene, furfurol, phenyl hydrazine, glycol derivatives, fumaric acid, keto-acids, or liquefied normally-gaseous hydrocarbons, or mixtures of the above solvents. The extracts may be subjected to dehydrogenation before or after the cracking treatment, e.g. at 400-700 DEG C. in presence of gases or vapours and under such conditions that hydrogen merely is split off. The dehydrogenation and the cracking may be carried out in the same chamber. Other methods of dehydrogenation comprise treatment with air or oxygen in presence of copper at 350 DEG C.: by heating with sulphur at 150-300 DEG C.; by treatment in presence of catalysts, e.g. those that bind hydrogen, e.g. selenium, tellurium, oxides of nitrogen, dilute nitric acid; by halogenation. Prior to the recovery of the unitary compounds the products may be refined to remove polymerization products by treatment with solvents. Mineral coal is extracted at 410 DEG C. with a mixture of tetrahydronaphthalene and cresol and the extract is cracked in a low - temperature carbonization retort at 600 DEG C. The vapours formed are dehydrogenated by passage for three seconds over active carbon impregnated with molybdenum and cobalt sulphides. The products obtained below 180 DEG C. comprise mainly benzene, toluene and higher homologues, while from the fractions of higher boiling-point acenaphthene, fluorene, anthracene, pyrene and its methyl derivatives and chrysene are separated by fractional crystallization. Specification 435,254 is referred to.