Patent GB-299419-A (GB)
Title: Purification of crude aromatic hydrocarbons
IPC: C07C7/148
Filed: 1928-10-08
Abstract: 299,419. Selden Co. ,(Assignees of Jaeger, A. 0.). Oct. 26, 1927, [Convention date]. Anthracene, phenanthrene. naphthalene and other aromatic hydrocarbons.-Aromatic hydrocarbons such anthracene, naphthalene and the like and benzene-containing light oils are purified by partial oxidation of the vapour by means of a limited quantity of oxygen in presence of suitable catalysts so as to destroy the impurities. A solid hydrocarbon such as anthracene, may be purified by a solvent such as benzene, toluene, naphtha, creosote oil, carbon disulphide acetone, carbon tetrachloride or pyridine and quinoline bases before or after the catalytic oxidation. Any oxidizing catalyst may be employed, preferably " stabilized " by the addition of compounds of alkali, alkaline earth or some earth metals having difficultly reducible oxides, and in some cases these stabilizers may predominate, especially where the stabilizer is a strong alkali such as a hydroxide of an alkali or alkaline earth metal; such highly alkaline catalysts are very suitable for the removal of carbazole from anthracene without destroying the phenanthrene. When anthracene is purified by solvents, the residual liquid contains chiefly carbazole, which on oxidation yields principally maleic acid. The hydrocarbon may be separated from the oxidation products or the crude reaction product may be used direct, for instance naphthalene may be mixed with further air and treated to produce naphthoquinone, phthalic anhydride, maleic acid &c. A very large number of catalysts is described, of which the following are typical. Iron titanium oxide (ilmenite) is mixed with caustic potash, soda, rubidia, caesia, or potassium carbonate or strontia and supported on pumice, the titanium oxide being replaced if desired by oxide of aluminium, zirconium, cerium, thorium, or nickel or by CoO2; crude anthracene is sprayed into a current of air at 200-260‹ C. and passed over the catalyst at 380-440‹ C., the proportion being one part by weight of anthracene to 20-30 parts of air. Cerium oxide is suspended in potassium nitrate solution and absorbed in pumice, or coated upon aluminium granules. Ferric oxide with or without copper, cerium, or nickel oxide is mixed with aluminium, zirconium, cerium, thorium, or cadmium oxide and an alkali or potassium nitrate or cyanide is added. Freshly-precipitated ferric oxide is suspended in potassium nitrate solution and sprayed upon pieces of pumice which are kept above 100‹ C.; the catalyst is placed in small tubes arranged in a medium of high heat conductivity such as a molten bath of lead, mercury-cadmium, mercury-lead, or fused salts such as sodium and potassium nitrates or nitrates and nitrites; the boiling-point of the bath is preferably the reaction temperature, and may be varied by varying the pressure upon the bath or the composition of the bath; in this example the ferric oxide may be partly or wholly replaced by compounds of silver, gold, platinum metals, or by copper or nickel oxide obtained from the nitrate, and the potassium nitrate may be partly or wholly replaced by other specified compounds, including potassium sulphate, bisulpbate. chloride, chlorate, bromide, fluoride and phosphates, and sodium nitrate, sulphate, chloride, bromide, and fluoride; complex compounds containing both the stabilizer and the catalytic agent, such as potassium and copper ferricyanides together with a stabilizer and also various silicates; dehydrating and dehydrogenating catalysts such as an oxide of aluminium, zirconium, and zinc, CeO, CeO2, MnO2 and PbO2 may be added, and for the total combustion of the carbazole, the oxides, salts or compound; of the elements of the 5th and 6th groups of the periodic system such as vanadium, tantalum, bismuth, antimony, chromium, molybdenum, tungsten and uranium may be used as well. Alumina, thoria and sodium nitrate are supported on pumice, the oxides being, if desired, wholly or partly replaced by ether specified oxides including zinc, cadmium, tin, beryllium, silicon, magnesium and barium, WO3, Mo2O5, UO2, and Mno., with the addition, if desired, of compounds of metals of the 5th and 6th groups such as AgVO3, Al4(V2O7)3, CeV2O7, and FeVO4 and the corresponding salts of tantalum, molybdenum, tungsten, and hexavalent uranium. " Bag-house super-cel Celite " is suspended in neutral potassium vanadate solution and ferric sulphate added, the mixture being made neutral by adding potash solution, the precipitate being washed and dried at 100‹ C.; this product is mixed with potassium aluminate solution, and potassium silicate solution is added to the suspension, yielding a catalyst of the nature of zeolite. Manganese sulphate is added to potassium, vanadate solution and the precipitate suspended in potassium bromide solution and sprayed upon pumice; the potassium bromide may be wholly or partly replaced by other specified salts, including potassium nitrite and acid fluoride and disodium phosphate. Basic copper carbonate is dissolved in ammonia solution, and potassium aluminate, copper nitrate and Kieselguhr are added, yielding a base-exchange body containing copper, alkalimetal, and aluminium; the precipitate is dried, and may be treated with potassium silicate and dried again; the diluted or undiluted catalysts may alternatively be coated upon quartz or pumice by the aid of potassium silicate. Siliceous diluents such as rocks, celite brick refuse, zeolites or silica or an intermediate silicate made by treating natural or artificial silicates such as leucite or zeolites with acids, are suspended in potassium aluminate solution, and potassium silicate and aluminium sulphate are added, and, if desired, a small quantity of sulphuric acid, leaving the liquor neutral or alkaline: or the other components may be added to the aluminium sulphate; instead of aluminate similar compounds of vanadium, tungsten, molybdenum, lead, zine or cadmium with or without aluminium, and instead of some or all of this aluminium sulphate, salts such as those of vanadium (especially vanadyl sulphate), zinc, cadmium, titanium, zirconium, copper, nickel, cobalt, silver, beryllium, cerium, tin, thorium, manganese, chromium, or iron may be used; and the alkali metal in these base exchanging bodies may be replaced partly or as far as possible by various other specified metals; for instance the baseexchange body may be treated with ammonium vanadate solution; catalytically active diluents such as 5 to 10 per cent of the metallates of the metals of the 5th and 6th groups such as silver copper, manganese, and iron vanadates, tungstates, molybdates, uranates, and tantalates may also be added. Cobalt nitrate solution containing suspended infusorial earth is treated with potassium hydroxide, and sodium silicate is added, the precipitate being added to aluminium sulphate solution, after which caustic potash is added until the alumina at first precipitated is redissolved, a gelatinous precipitate being formed after some time; alternatively a mixture of aluminium and cobalt salts may be added to sodium silicate solution. Neutral iron silicate obtained from ferric sulphate and sodium silicate. is suspended in sodium silicate solution and ferric sulphate solution is added, the solution remaining alkaline, an iron zeolite with ferric silicate embedded in it being produced. Specification 281,307 is referred to. The Specification as open to inspection under Sect. 91 (3) (a) describes the treatment of aromatic compounds, and is not limited to the vapour phase. This subject-matter does not appear in the Specification as accepted. Reference has been directed by the Comptroller to Specifications 286,212, 291,419, 295,270 and 296,071.