Patent GB-769217-A (GB)
Title: Improvements in or relating to alumina and alumina-containing materials
IPC: C01F7/428
Filed: 1954-07-26
Abstract: A catalyst based on alumina prepared by reacting aluminium with water (see Group III) is employed in reforming hydrocarbons.  Thus a platinum/alumina catalyst may be employed in gasoline reforming at 315-595 DEG  C. under 3.4 to 68 atmospheres pressure with a weight hourly space velocity of 0.5 to 20 in the presence of 0.5 to 20 mols. of hydrogen per mol. of hydrocarbon.  According to examples: (6) a gasoline fraction having a boiling-point from 110 DEG  to 212 DEG  C. and a F1 clear octane number of 34.0 was subjected to reforming in the presence of an alumina catalyst containing 0.3 per cent platinum at 460 DEG  C., 34 atmospheres pressure, a liquid hourly space velocity of 2.03 and with a hydrogen/hydrocarbon mol. ratio of 3.02. The octane number was increased to 89.2; (8) an alumina silica catalyst containing 0.5 per cent palladium was employed to reform naphtha having a boiling-point of 93 DEG  to 204 DEG  C., at 504 DEG C., a pressure of 34 atmospheres, a hydrogen/hydrocarbon mol. ratio of 7 and a weight hourly space velocity of 3.0.  The octane number was raised 40 units.ALSO:<PICT:0769217/III/1> In a process for producing alumina especially suitable as a catalyst base, by reacting aluminium metal with water in the presence of mercury, aluminium metal particles of not more than 25 mm. in greatest dimension are introduced into a reaction zone and agitated therein in the absence of added acid in the presence of an excess of liquid water and in the presence of metallic mercury or a mercury compound in an amount from 0.00135 to 13.5 mol. per cent of mercury relative to the aluminium metal, at an elevated temperature below 374 DEG C. until the major portion of the aluminium metal is converted to crystalline or gel alumina and the alumina particles are separated from the reaction slurry and dried.  For reaction temperatures up to 205 DEG C. the alumina forms as a gel whilst from 205 to below 374 DEG C. crystalline alumina is produced. Mercury or its salts with organic or inorganic acids, or ammono-basis mercuric bromide or chloride may be employed.  A suitable apparatus is shown in the Figure where aluminium chips are introduced from a vessel 1 into a reactor 4 provided with a slurry circulation device 6 and supplied with water at 100 DEG C. through line 5 which carries the necessary mercury promotor.  The alumina slurry is withdrawn through line 9 and passed to separator 11 which may be a centrifuge, whereby the alumina is separated from unreacted aluminium and mercury, the alumina being withdrawn as product through line 15 and the aluminium fines and mercury being withdrawn through line 17 to pass to a mercury receiver 14. Water containing small amounts of alumina and promoter are withdrawn through line 16 and hydrogen is vented from the reactor through line 21.  The process may be employed to produce an alumina-combined halogen composite catalyst by employing a halide of mercury as a promoter for the reaction of the aluminium and water, whereby the halogen combines with the alumina, the preferred amount of so combined halogen being from 0.1 to 8 per cent by weight.  The slurry of such a composite withdrawn from the process may be dried at up to 60 DEG C. and thereafter calcined at 315 to 870 DEG C. whereby any traces of mercury or its compounds which may be present are volatilized.  The halided alumina composite catalyst may be further composited with other catalytic components, for example with platinum for use as a reforming catalyst or as an isomerization catalyst by subliming anhydrous aluminium chloride on to the dried halided alumina composite in an in an amount up to 50 per cent by weight. The latter catalyst may be employed for the isomerization of pure paraffinic or pure naphthenic compounds or complex mixtures thereof at 500 to 250 DEG C. and 1000 atmospheres pressure and preferably in the presence of a hydrogen chloride activator and/or hydrogen to control side reactions.  The alumina may be combined with a group 8 metal catalyst with or without admixture with silica, titania or boran oxide.  Thus plantinum, nickel, cobalt, ruthenium, rhodium, osmium, iridium, palladium or mixtures thereof may be employed preferably in a concentration range of 0.01 to 10 per cent by weight calculated as metal of the final catalyst.  The catalyst complex is preferably subjected to a high temperature treatment or calcination in an oxidizing, reducing or inert atmosphere at 315 to 870 DEG C. Molybdenum catalysts may be prepared by compositing the alumina or alumina-halogen composite calcined if desired, with molybdenum and preferably also with a metal of the iron group after which the composite is calcined.  Halogen may be incorporated in such a catalyst either by employing a mercury halogen compound as a promoter for the aluminium/water reaction or alternatively the halogen may be added to the alumina before or after drying as an aqueous solution of a hydrogen halide, aluminium halide or mixtures thereof. Alternatively a metal ammonium or amine salt may supply the halide which will preferably be within the range of 0.01 to 20 per cent by weight.  A preferred catalyst contains 1 to 25 per cent each of cobalt and molybdenum oxides together with combined halogen.  Such a catalyst may be sulphided for example with hydrogen sulphide at 205 to 540 DEG C. or the sulphided catalyst may be obtained by using the oxide catalyst for the treatment of hydrocarbons containing sulphur compounds. A catalyst containing the alumina of the invention with a group 8 metal and particularly platinum is particularly suitable for gasoline reforming and may be used for the dehydrogenation of hydrocarbon fractions such as naphthenes to produce aromatics, paraffins to produce olefins and mono-olefins to produce di-olefins. The catalyst may also be used for dehydrocyclization reactions such as the conversion of n-hexane to benzene, for isomerization reactions, hydrogenation reactions including non-destructive and destructive hydrogenation and oxidation of hydrocarbons to form oxygenated derivatives and for desulphurizing sulphurcontaining fractions.  Gasoline reforming may be effected at 315 to 595 DEG C. under a pressure of 3.4 to 68 atmospheres with a weight hourly space velocity of 0.5 to 20 in the presence of hydrogen at a mol ratio of from 0.5 to 20 mols of hydrogen per mol of hydrocarbon.  Preferably such hydrogen is produced in the process and recycled.  The molybdenum alumina catalyst is particularly suitable for the removal of impurities from gasoline and other hydrocarbon oils in the presence of hydrogen at 150 to 425 DEG C. at pressures ranging up to 340 atmospheres, 3.5 to 350 litres of hydrogen per litre of gasoline being employed, or more if the gasoline fraction contains unsaturates.  The molybdenum containing catalyst may also be used for dehydrogenation and reforming at 425 to 650 DEG C. or for non-destructive hydrogenation at 95 to 370 DEG C.  Hydrocarbon charges may be purified in the presence of hydrogen and the molybdenum alumina catalyst as above described and the so purified charge subjected to contact with an alumina catalyst containing platinum; for example a gasoline fraction may be treated with alumina, molybdenum and cobalt oxide catalyst at 150 to 425 DEG C. in the presence of hydrogen and then subjected to reforming in the presence of an alumina, halogen, platinum catalyst at 425 to 595 DEG C. the hydrogen being separated from the reforming effluent and supplied to the initial treating step.  According to examples (1) refined aluminium metal particles were reacted with distilled water and 0.089 per cent of mercury chloride at 97 DEG C. whereby 99.3 per cent of the aluminium reacted to form an alumina hydrogel (4) alumina chips were reacted with distilled water containing mercuric fluoride at 99 DEG C. to produce a white alumina gel containing 0.35 per cent fluorine which was dried at 149 to 260 DEG C., ground with a pilling lubricant, formed into pills, and the pills heated in air at 454 DEG C. to burn off the lubricant.  A chlorine containing alumina may be similarly prepared (6) the alumina hydrogel of (1) was treated with 4.8 per cent hydrofluoric acid solution to give 0.18 per cent fluorine incorporation and the slurry evaporated to dryness and the alumina dried at 160 DEG C.  The ground alumina was mixed with a pilling lubricant, pilled, air heated and calcined in air at 650 DEG C. after which the pills were impregnated with chloroplatinic acid dissolved in an aqueous ammonium hydroxide solution to produce a final catalyst containing 0.3 per cent platinum.  After impregnation the composite was calcined at 500 DEG C. and employed in the reforming of a gasoline fraction having a boiling point of from 110 to 212 DEG C. and a F-1 clear octane number of 34.0.  The temperature was 460 DEG C. the pressure, 34 atmospheres, the liquid hourly space velocity, 2.03, and the hydrogen to hydrocarbon mol ratio, 3.02.  The octane number was increased to 89.2.  (8) The alumina of (4) was submerged in a solution of waterglass and hydrochloric acid was added to precipitate silica on the alumina after which the oxide composite was washed, dried and calcined at 816 DEG C.  The calcined composite was impregnated with chloropalladium acid to incorporate 0.5 per cent palladium. Such a catalyst when employed to reform naphtha having an initial boiling point of 93 DEG C. and an end boiling point of 240 DEG C. raised the octane number 40 units.  (11) Alumina gel prepared as above was dried, ground and pilled and impregnated with a solution of molybdic acid, cobalt nitrate, hydrogen fluoride and ammonium bifluoride and the composite dried at 100 DEG C. and calcined in air at 427 DEG C.  The resulting catalyst containing 3 per cent molybdenum oxide, 2 per cent cobalt oxide, 7 per cent of fluorine and the remainder alumina had an apparent bulk density of 0.58 and was e