Patent GB-498859-A (GB)
Title: A process for carrying out catalytic dehydrogenation reactions of non-aromatic organic compounds
IPC: B01J19/00
Filed: 1937-07-16
Abstract: In effecting the catalytic dehydrogenation of non-aromatic organic compounds in contact with a metallic surface at temperatures of about 400 DEG  C. or more, generally up to about 900 DEG  C., and under such conditions that cracking is substantially obviated, carbon formation catalyzed by the metallic surface is inhibited by treating the same at an elevated temperature with an amount of added sulphur, hydrogen sulphide or a compound yielding the latter sufficient to poison it.  Hydrogen sulphide is generally employed, but organic compounds such as mercaptans, mercaptides, thioethers, and polysulphides may be used.  The interior of the metallic reaction vessel may be pretreated, preferably at the same temperature as is used in the dehydrogenation, for example for 5 to 120 mins. with hydrogen sulphide, or treating agent may be added to the compound to be dehydrogenated, or both methods may be utilized.  The minimum effective amount is employed.  Dehydrogenation reactions specified are conversion of paraffins, including cyclo-paraffins, to olefines, using metal or metal oxide catalysts, e.g. activated alumina, conversion of primary or secondary alcohols to aldehydes or ketones, e.g. ethyl alcohol to acetaldehyde, isopropyl alcohol. to acetone, secondary butyl alcohol to methyl ethyl ketone, methallyl alcohol to methacrolein, borneol and isoborneol to camphor, cyclohexanol to cyclohexanone, and fenchyl alcohol to fenchone.  Catalysts such as molybdenum sulphide which are not poisoned by sulphur or its compounds or those which have a tolerance therefor, e.g. activated alumina or charcoal, silica gel, magnesite, zinc, chromium or thorium oxides, alumina or magnesite impregnated with chromium chromite, may be used, the amount of sulphur or its compounds added being insufficient to decrease the activity of the catalyst.  In the dehydrogenation of butanes or other hydrocarbons in tubes of iron or steel or their alloys the addition of 0,5 per cent sulphur is effective.  In examples: (1) isopropyl alcohol is passed through a steel tube packed with a brass catalyst at 425-495 DEG  C.  Carbon formation is inhibited by addition of ,0025 per cent of sulphur in the form of H2S; (2) ,005 per cent of sulphur is added and a p reaction temperature of 450-500 DEG  C. employed.  No carbon is deposited but the catalyst gradually loses its activity; (3) isobutane mixed with about 0,5 per cent H2S is dehydrogenated using a steel reaction tube packed with activated alumina at about 600 DEG C.; (4) the packed tube is pretreated with H2S at about 600 DEG  C. for 30 mins. and used for conversion of butane to butene. Specification 467,470 is referred to.  The Specification as open to inspection under Sect. 91 is not limited to the dehydrogenation of non-aromatic compounds but covers endothermic reactions involving organic compounds generally.  Other reactions specified are the cracking of carbonaceous materials, e.g. petroleum, shale oils, animal and vegetable oils, coal, tars, asphalts, and pitches, of paraffins to olefines and aromatics, and of paraffins or olefines to acetylenes, and the cracking and conversion of olefines to aromatic. In one example, stove oil is cracked to naphthalene tar and olefinic gas at 800 DEG  C. in a chromium-molybdenum steel tube, 1 per cent of H2S being added or the tube pretreated with sulphur vapour or dimethyl sulphide.  This subject-matter does not appear in the Specification as accepted.ALSO:In effecting the catalytic dehydrogenation of non-aromatic organic compounds in contact with a metallic surface at temperatures of about 400 DEG  C. or more, generally up to about 900 DEG  C., and under such conditions that cracking is substantially obviated, carbon formation catalyzed by the metallic surface is inhibited by treating the same at an elevated temperature with an amount of added sulphur, hydrogen sulphide or a compound yielding the latter sufficient to poison it.  Hydrogen sulphide is generally employed, but organic compounds such as mercaptans, mercaptides, thioethers, and polysulphides may be used. The interior of the metallic reaction vessel may be pretreated, preferably at the same temperature as is used in the dehydrogenation, for example for 5 to 120 mins. with hydrogen sulphide, or the treating agent may be added to the compound to be dehydrogenated, or both methods may be utilized.  The minimum effective amount is employed.  Dehydrogenation reactions specified are conversion of paraffins, including cyclo-paraffins, to olefines, using metal or metal oxide catalysts, e.g. activated alumina, conversion of primary or secondary alcohols to aldehydes or ketones, e.g. ethyl alcohol to acetaldehyde, isopropyl alcohol to acetone, secondary butyl alcohol to methyl ethyl ketone, methallyl alcohol to methacrolein, borneol and isoborneol to camphor, cyclohexanol to cyclohexanone, and fenchyl alcohol to fenchone.  Catalysts such as molybdenum sulphide which are not poisoned by sulphur or its compounds or those which have a tolerance therefor, e.g. activated alumina or charcoal, silica gel, magnesite, zinc, chromium or thorium oxides, alumina or magnesite impregnated with chromium chromite, may be used, the amount of sulphur or its compounds added being insufficient to decrease the activity of the catalyst.  In the dehydrogenation of butanes or other hydrocarbons in tubes of iron or steel or their alloys the addition of 0,5 per cent sulphur is effective.  In examples: (1) isopropyl alcohol is passed through a steel tube packed with a brass catalyst at 425-495 DEG  C.  Carbon formation is inhibited by addition of ,0025 per cent of sulphur in the form of H2S; (2) ,005 per cent of sulphur is added and a reaction temperature of 450-500 DEG  C. employed.  No carbon is deposited but the catalyst gradually loses its activity; (3) isobutane mixed with about 0,5 per cent H2S is dehydrogenated using a steel reaction tube packed with activated alumina at about 600 DEG  C.; (4) the packed tube is pretreated with H2S at about 600 DEG  C. for 30 mins. and used for conversion of butane to butene.  Specification 467,470, [Group III], is referred to.  The Specification as open to inspection under Sect. 91 is not limited to the dehydrogenation of non-aromatic compounds but covers endothermic reactions involving organic compounds generally.  Other reactions specified are the cracking of carbonaceous materials, e.g. petroleum, shale oils, animal and vegetable oils, coal, tars, asphalts, and pitches, of paraffins to olefines and aromatics, and of paraffins or olefines to acetylenes; cracking and conversion of olefines to aromatics, e.g. benzene, naphthalene, anthracene, and toluene; de-alkylation of, e.g. toluene to benzene, cresol to phenol, and alkyl quinolines to quinoline; dehydration of aliphatic alcohols to olefines and diolefines; decarboxylation of acids and esters; reactions involving formation or reaction of carbon monoxide; conversion of ethylbenzene to styrene.  Examples describe the conversion of propane or propene to aromatics, e.g. benzene, by passage through a steel tube at 700-900 DEG  C., about 2 per cent of H2S being added or the tube pretreated with this gas; the cracking of stove oil to naphthalene tar and olefinic gas at 800 DEG  C. in a chromiummolybdenum steel tube, 1 per cent of H2S being added or the tube pretreated with sulphur vapour or dimethyl sulphide.  This subject-matter does not appear in the Specification as accepted.