Patent GB-769026-A (GB)
Title: Improvements in or relating to alumina and alumina-containing materials
IPC: B01J21/04
Filed: 1954-07-26
Abstract: A catalyst based on alumina prepared by reacting aluminium metal with water in the presence of a mercury promoter (see Group III) containing a Group VIII metal catalyst component, particularly platinum, is employed for reforming hydrocarbons at temperatures normally from 315 DEG  to 595 DEG  C., pressures from 3.4 to 68 atmospheres, weight hourly space velocities from 0.5 to 20 and in the presence of hydrogen at a mol. ratio of 0.5 to 20 mols. of hydrogen per mol. of hydrocarbon.  According to an example (1) a catalyst containing alumina, 0.3 per cent platinum and 0.2 per cent combined fluorine was employed to reform a straight-run naphtha having a boiling range of 110 DEG  to 212 DEG  C. and an F-1 clear octane number of 34 at 460 DEG  C. and 34 atmospheres pressure with a liquid hourly space velocity of 1.98 and a hydrogen to hydrocarbon mol. ratio of 3.25.  The initial boiling-point of the reformed product was 48 DEG  C., the Reid vapour pressure increased from 0 to 5.0 and the octane number increased from 34.0 to 85.5. The dispersion at 20 DEG C. increased from 73.0 to 112.2 and the aromatic content was increased.ALSO:In a process for obtaining alumina by reacting aluminium metal with water in the presence of mercury or a mercury compound and a small amount of an acid, the conversion of the aluminium to alumina is effected in a single reaction stage at a temperature less than 374 DEG C. in an agitated mixture of aluminium metal particles with excess of liquid water containing the mercury or compound thereof in an amount from 0.01 to 50 per cent by weight of the aluminium metal and in the presence of an acid compound which may be a mono or polybasic inorganic acid, a polybasic organic acid or acid-acting salts thereof until at least the major portion of the aluminium is converted to finely divided crystalline or gel particles of alumina which are separated from the reaction mixture.  The acid compound is employed in an amount corresponding to at least 0.01 equivalents of acid anion per equivalent of aluminium metal, but less than 0.13 equivalents of monobasic inorganic acid anion, less than 0.50 equivalents of dibasic inorganic acid anion and less less than 1.0 equivalents of dibasic organic and tribasic inorganic and organic acid anion per equivalent of aluminium metal.  At reaction temperatures up to 205 DEG C. the alumina is formed as a gel while at temperatures above 205 to below 374 DEG C. crystals of alumina are usually produced.  The mercury compound may be an organic or inorganic salt of mercury or ammonobasic mercuric bromide or chloride whilst the acidic compound may comprise the monobasic inorganic acids, sulphuric acid and phosphoric acids, or polybasic organic acids such as oxalic, malonic, succinic, maleic, phthalic, tartaric, and citric. Acid-acting salts may comprise the halide salts such as ammonium or aluminium chlorides and fluorides.  When alumina gel is produced, drying within the temperature range of 0 to 205 DEG C. produces mainly Gibbsite alumina whilst if the drying is carried out 205 DEG C. or above.  Bohmite tends to be formed.  The alumina before or after drying may be composited with silica, titania or boron oxide and the composite may be further composited with a catalyst from Group VIII of the periodic table, particularly platinum.  Such a catalyst preferably contains 0.01 to 1 per cent by weight of platinum and 0.1 to 8 per cent by weight of halogen, preferably 0.1 to 3 per cent by weight being combined fluorine. Such halogen may be added before or after drying the alumina, preferably in the form of an aqueous hydrogen halide before the other components are composited with the alumina.  The platinum may be introduced as a solution of chloroplatinic acid which has been treated with hydrogen sulphide, or alternatively the alumina may be treated with chloroplatinic acid and ammonium hydroxide at a pH from 5 to 10; alternatively the platinum may be introduced as solutions, colloidal solutions or suspensions of platinum-cyanide, hydroxide, oxide or sulphide, if desired in alcoholic or ethereal solutions.  Other Group VIII metals such as nickel, cobalt, ruthenium, rhodium, osmium, iridium and palladium or mixtures thereof may also be employed generally within the range of 0.01 to 10 per cent by weight of the final catalyst.  A catalyst composite so produced may be calcined at 315 to 850 DEG C. in an oxidizing reducing or inert atmosphere or the catalyst may be calcined successively in hydrogen and air.  Such alumina based catalyst are particularly suitable for gasoline reforming in a fixed, fluidized or entrained bed or as a suspension in liquid hydrocarbons passed into the reaction zone.  The catalyst may also be used for the dehydrogenation of hydrocarbon fractions such as naphthenes to produce aromatics, paraffins to produce olefins and mono-olefins to produce diolefins.  It is also suitable for dehydrocyclization reactions such as the conversion of normal hexane to benzene, isomerization, hydrogenation and for oxidation of hydrocarbons. According to examples (1) alumina chips of over 99 per cent purity were reacted with water at 97 DEG C. in the presence of mercuric chloride and oxalic acid whereby a stiff alumina gel formed which was decanted and treated with 4.8 per cent solution of hydrofluoric acid to incorporate 0.2 per cent combined fluorine.  The slurry was evaporated and dried at 149 to 163 DEG C., after which the alumina was ground and screened.  The ground alumina was then pilled with a hydrogenated vegetable oil and heated in air to 500 DEG C. to burn out the pilling lubricant and then calcined at 650 DEG C. after which the alumina-combined fluorine pills were impregnated with chloroplatinic acid and ammonium hydroxide to incorporate 0.3 per cent platinum.  The composite was calcined in air at 500 DEG C. and thereafter employed to reform naphtha.  (2) Aluminium of 99.9 per cent purity was converted to alumina hydrogel by means of hydrochloric acid and mercuric chloride in water at 99 to 100 DEG C. The gel product was separated from the mercury globules and converted to a platinized catalyst as described in Example (1).