Patent GB-736875-A (GB)
Title: Process for continuously operating the oxo synthesis
IPC: C07C27/22
Filed: 1953-01-12
Abstract: An Oxo synthesis is effected in continuous manner by passing an intimate admixture of an organic compound containing olefinic unsaturation, an aqueous solution of a cobalt salt and/or of an iron salt, CO and H2 through an extended reaction space at elevated temperature and a pressure above 50 kg./sq. cm. at such a rate that no substantial separation of the mixture into its component parts occurs.  The use of acid cobalt sulphate solutions is preferred.  The reaction space may be of tubular form and be 150-400 metres in length and 4-50 mm., preferably 10-20 mm., in diameter.  The products are separated into gaseous, aqueous and oily phases.  After separation of the gaseous phase and treatment with water the organic products are freed from residual metal and acetals by passing through a long reaction space, e.g. a tube. For the Oxo reaction it is preferred that tubular coils or spirally or helically wound reaction spaces immersed in a heat transfer liquid, especially a water-bath, are used.  The tube may be immersed in baths so that the temperature increases in the direction of flow.  Preferably the reaction mixture is passed upwardly through the tubes and generally turbulent flow will prevail.  The mixing of the reactants is effected in conventional fashion, e.g. by means of a centrifugal pump and is assisted by the addition of small amounts of a wetting agent or emulsifier, e.g. an alkyl aryl sulphonate.  Recovered catalyst may be returned to the synthesis.  In some cases it is advantageous to leave a portion of the liquid reaction product in the cycle.  CO and H2 may be introduced into the reactants passing through the reaction space at various points to maintain a constant concentration of these gases throughout the space.  Metals or alloys resistant to corrosion should be used for the tubes, chrome-nickel steel and copper-plated tubes being recommended. The Oxo reaction is accelerated if a certain surface area of metallic iron or cobalt is present in the reactor, e.g. the reactor walls may have an inner lining of the metal.  In the Oxo synthesis, preferred pressures are 100-150 kg./sq. cm. and temperatures are 140-170 DEG  C.  During the purification of the products temperatures of 100-250 DEG  C., preferably about 200 DEG C., are used, the products emulsified with water, being passed at such a rate that demulsification of the mixture is avoided.  The quantity of water added should exceed that required for the splitting of the acetals, generally an addition of 10-20 per cent of water suffices.  The mixing of the desired products with water may be performed as in the first stage.  Finally an oily phase is separated from an aqueous phase and precipitated metallic hydroxides removed by filtration.  The Oxo aldehydes may be converted into alcohols by methods known.  Advantageously, to avoid losses due to clogged tubes the reaction is effected in a cylindrical pressure-resistant vessel internally provided with a screw of low pitch.  The outer edges of the screw surfaces define the reaction channel which should lie as close as possible to the inner wall of the cylindrical, pressure vessel.  Diagrams are provided showing the use of such screw surfaces and equipment in which three reactors are used in series.  In an example a mixture of a C8 olefinic fraction, an acid cobalt sulphate solution of pH 5 also containing magnesium sulphate and water gas is passed at 150 kg./sq. cm. into a coil of copper tube 4 mm. in diameter and 400 metres long placed in a water-bath at 150 DEG  C. and containing about 40 metres from its inlet an iron wire of 50 metres length and 2 mm. diameter, the liquid organic product is separated, mixed with water and freed from cobalt and acetals by passing through a coil of copper tube 4 mm. in diameter and 50 metres long in a water-bath at 200 DEG  C., the aldehydes thus obtained being hydrogenated over a nickel catalyst to yield alcohols. Specifications 711,696 and 734,030 are referred to.ALSO:A catalyst used in an Oxo-synthesis comprises an aqueous acidic solution of cobalt sulphate.  Advantageously the solutions contain magnesium sulphate in such a quantity that approximately 20 grams of Mgo/litre are present per 10 grams of cobalt contained in 1 litre of solution. In the example the catalyst solution of cobalt sulphate contains 8 grams of cobalt per litre and 15 grams per litre of magnesium oxide, in the form of magnesium sulphate, the solution being acidified to pH 5 with oxalic acid.  Specifications 711,696 and 734,030, [Group IV (b)], are referred to.