Patent GB-680509-A (GB)
Title: Process for the production of phenols and the phenols so produced
IPC: B01J23/78
Filed: 1950-12-05
Abstract: Phenols are obtained by contacting cycloaliphatic alcohols or ketones or mixtures thereof with a catalyst comprising a major molar amount of iron oxide and a minor molar amount of an alkaline compound of an alkali or alkaline earth metal; the dehydrogenation takes place preferably between 350 DEG  and 650 DEG  C., e.g. 450-600 DEG  C.; the starting materials have the hydroxyl group or ketonic oxygen atom attached directly to a 6-membered cycloaliphatic ring.  The alkaline compound in the catalyst may be a sodium, potassium, lithium, rubidium, caesium, calcium or strontium compound, preferably potassium oxide, hydroxide or carbonate.  It may also contain a difficultly-reducible metallic oxide such as an oxide of chromium, manganese, bismuth, titanium or zirconium.  A preferred catalyst comprises iron and potassium oxides with chromium oxide in a lesser molar proportion than the potassium oxide.  Such a catalyst mixture is calcined at 700-1000 DEG  C., in an atmosphere under which no appreciable formation of iron chromite takes place, until the available surface is decreased below 30 sq.m./gm.  The catalyst may be in the form of pellets, fragments, powders, dusts or on a support or carrier, but substances like magnesia and alumina which react with iron oxide should be absent.  The alcohol or ketone is passed in gaseous form over the catalyst, preferably mixed with steam. Fractional condensation of the effluent and/or fractional distillation of the condensate gives the desired phenol, an azeotrope with the starting material often being formed, which is recycled to the reactor.  If insufficient phenol is produced to form the azeotrope, another agent, such as 1 : 4-butenediol, may be added to remove the starting material in this way.  Examples show the production of phenol from cyclohexanone and 3 : 5-xylenol from isophorone.  Other specified starting materials are cyclohexanol and various alkyl - substituted cyclohexanols, cyclohexanones, cyclohexenols and cyclohexenones, the alkyl groups containing 1-8 carbon atoms.  Preferred starting materials contain only carbon, hydrogen and oxygen atoms and have 6-20 carbon atoms in the molecule.ALSO:Catalysts for the production of phenols from cycloaliphatic alcohols and ketones comprise a major molar amount of iron oxide and a minor molar amount of an alkaline compound of an alkali or alkaline earth metal.  The latter may be a sodium, potassium, lithnium, rubidium, caesium, calcium or strontium compound; potassium oxide, hydroxide or carbonate is preferred. There may also be present a further difficully reducible oxide, e.g. of chromium, manganese, bismuth, titanium or zirconium, such oxide being preferably present in a lesser molar amount than the alkaline compound; it should not be chemically combined with the other oxide. The catalyst should be free from materials such as magnesia and alumina which react with iron oxide to form inactive compounds.  The catalyst may be used in the form of pellets, fragments, powders or dust with or without inert materials as supports.  The catalyst may be made by mixing the alkaline compound with molten iron in the presence of oxygen, or with molten iron oxide (see U.S.A. Specification 1,489,497).  The preferred catalysts containing chromium oxide are calcined at 700 DEG C-1000 DEG C in an atmosphere under which no appreciable formation of iron chromite takes place, until the available surface is less than 30 sq.n/g. (see U.S.A. Specification 2,408,140).  An example is given of the production of a catalyst containing 88 per cent iron oxide (calculated as Fe2O3), 9.5 per cent potassium oxide and 2.5 per cent chromium oxide.  A moist paste is made of ferric oxide, potassium carbonate and chromium oxide and calcined in the form of pellets at 900 DEG C for 12 hours. Before use it is treated with a 5:1 mol mixture of water and hydrogen at 600 DEG C to convert the ferric oxide mainly into Fe3O4.  U.S.A. Specification 2,414,585 also is referred to.