GB297398A - Process for splitting hydrocarbons - Google Patents

Abstract

297,398. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). May 16, 1927. Olefines; diolefines. - Mineral or artificially prepared hydrocarbons containing more than four .carbon atoms in the molecule are converted into olefines and diolefines containing a smaller number of carbon atoms in the molecule than the initial materials by bringing their vapours, at normal or reduced pressure and at a temperature of at least 600‹ C., into contact with catalysts consisting wholly or for the most part of difficulty reducible metallic oxides or mixtures or compounds thereof, alone or in conjunction with supports. A metallic oxide is defined as difficultly reducible if it is not reduced to the metallic state in hydrogen at temperatures up to 600‹ C. The preferred catalysts consist of or are derived from the difficulty reducible oxides of metals situated on or near the maxima, of the atomic volume curve, and in this connection reference is made (1) to the oxides of the alkali and alkaline-earth metals (including magnesium and beryllium) and their oxygen-containing salts, such as aluminates, chromates, tungstates, vanadates, uranates, and phosphates, (2) to oxide combinations which readily emit electrons, such as strontium oxide-barium oxide combinations, alone or on a platinum substratum, and (3) to the oxides of scandium, titanium, yttrium, zirconium, lanthanum, tungsten, molybdenum, thorium, and uranium or mixtures of these or their compounds. The difficultly reducible oxides of metals situated on or near the minima of the atomic volume curve, such as aluminium, chromium, and zinc, are less suitable, but they may be used in the form of their salts with oxygen-containing acids of elements of the fifth, sixth, and seventh periodic groups forming not readily volatile oxides, such as phosphorus, chromium, and vanadium. The catalysts may be used in lump form or deposited on carriers, such as magnesium or aluminium silicate, and metals having a feeble dehydrogenating action, such as copper, platinum, molybdenum, or tungsten, may also be present. Metals having a strong dehydrogenating action, such as iron or nickel, are beneficial if added in small amounts. The process may be carried out in the presence or absence of gases such as nitrogen, carbon dioxide, and water vapour, but halogens or their .compounds, or substantial amounts of hydrogen, must not be present. According to the examples, (1) tetrahydrobenzene vapour is passed at 625‹ C. through a furnace made of porcelain, clay, or noble metal and charged with lumps of lime; the products are fractionally cooled and include ethylene, propylene, butadiene, and butylene; (2) hexahydrobenzene is passed at 600‹ C. through an apparatus made of or lined with quartz or clay and charged with cubes of calcium aluminate; the products include ethylene and butadienes; (3) the vapour of Russian benzine is passed at 625‹ C. through a metal apparatus internally enamelled and charged with lumps of lime; liquid unsaturated hydrocarbons are obtained.