GB366107A - Improvements in the thermal treatment of organic substances - Google Patents

Abstract

In thermal treatments of organic products, such as the cracking of oils, the conversion of methane and its homologues with steam or carbon dioxide into carbon monoxide and hydrogen, or in the reduction of phenol, cresol, and the like with hydrogen, the deposition of carbon is avoided by providing the surfaces of ceramic apparatus which come into contact with the hot organic materials, with a complete or partial covering of oxides of chromium, tungsten, vanadium, or uranium. For example, chamotte tubes or bricks or unglazed porcelain tubes are impregnated with aqueous chromic acid or chromium salts (or chromates which form chromium oxide on heating) and then heating, for instance to 1600 DEG C.; or the metal compounds may be incorporated in the materials from which the ceramic material is made. Catalysts may also be employed, incorporated in the surfaces in a similar manner. In examples (1) an internally unglazed porcelain tube is soaked with a 50 per cent aqueous chromic acid and dried at 400 DEG C., this being repeated three times; methane is passed through this tube at 1075-1100 DEG C. to produce benzene hydrocarbons and hydrogen; (2) methane is passed through a fireclay tube impregnated with chromic acid and is converted into benzene hydrocarbons and hydrogen at 1100-1200 DEG C.; (3) vapour of paraffin oil (boiling point 330-380 DEG C.) is passed at 650-700 DEG C. through a porcelain tube impregnated with chromic acid, 41 per cent of oils and 61 per cent of gases being produced; of the oils 60 per cent are of boiling point up to 200 DEG C. and 16 per cent of boiling point 200-300 DEG C., while the gas contains 40 per cent of olefines, 48 per cent of methane and its homologues and 10 per cent of hydrogen; (4) ethylene is passed at 700-750 DEG C. through a similar tube, 15 per cent of the ethylene being converted into a liquid containing 50 per cent of benzene and 50 per cent higher aromatic hydrocarbons; the gas contains 39 per cent of ethylene, 38 per cent of methane, and 21 per cent of hydrogen. Specification 317,359, [Class 32, Distilling &c.], is referred to.ALSO:In thermal treatments of organic products, such as the cracking of oils, the polymerization of olefines or cracking gases into benzene, the conversion of methane into benzene or olefines, the conversion of methane and its homologues with steam or carbon dioxide into carbon monoxide and hydrogen, or in the reduction of phenol, cresol, and the like with hydrogen, the deposition of carbon is avoided by providing the surfaces of ceramic apparatus which come into contact with the hot organic materials, with a complete or partial covering of oxides of chromium, tungsten, vanadium, or uranium. For example, chamotte tubes or bricks or unglazed porcelain tubes are impregnated with aqueous chromic acid or chromium salts (or chromates which form chromium oxide on heating) and then heating for instance to 1600 DEG C.; or the metal compounds may be incorporated in the materials from which the ceramic material is made. Catalysts may also be employed, incorporated in the surfaces in a similar manner. In examples (1) an internally unglazed porcelain tube is soaked with a 50 per cent aqueous chromic acid and dried at 400 DEG C., this being repeated three times; methane is passed through this tube at 1075-1100 DEG C. to produce benzene hydrocarbons and hydrogen; (2) methane is passed through a fireclay tube impregnated with chromic acid and is converted into benzene hydrocarbons and hydrogen at 1100-1200 DEG C.; (3) vapour of paraffin oil (b.p. 330-380 DEG C.) is passed at 650-700 DEG C. through a porcelain tube impregnated with chromic acid, 41 per cent of oils and 61 per cent of gases being produced; of the oils 60 per cent are of b.p. up to 200 DEG C. and 16 per cent of b.p. 200-300 DEG C., while the gas contains 40 per cent of olefines, 48 per cent of methane and its homologues and 10 per cent of hydrogen; (4) ethylene is passed at 700-750 DEG C. through a similar tube, 15 per cent of the ethylene being converted into a liquid containing 50 per cent of benzene and 50 per cent higher aromatic hydrocarbons; the gas contains 39 per cent of ethylene, 38 per cent of methane and 21 per cent of hydrogen. Specification 317,359 [Class 2 (iii), Dyes &c.], is referred to.