Patent GB-309382-A (GB)
Title: Oxidation of hydrocarbons
IPC: C07C27/10
Filed: 1927-10-06
Abstract: 309,382. Markcs, E. C. R., (Alox Chemical Corporation). Oct. 6, 1927. Formic, acetic, propionic, and other carboxylic acids; hydroxy acids; ketonic acids; aldehydes; ketones; alcohols. - Aliphatic hydrocarbons or aromatic hydrocarbons containing an aliphatic chain are oxidized in liquid phase with air or other gas containing free oxygen at about 100- 150‹ C. and at a pressure of 100-300 lb. in presence of a catalyst such as a compound of manganese, copper or iron (manganese oleate and stearate being mentioned) or a ketonic product of the oxidation, the process being carried on until the mass is completely emulsifiable, when the simple carboxylic acids are separated, alkali solution is added and the unsaponifiable portion is separated from the soap. The oil is placed in a cylinder 1 which may be lined with incorrodible metal such as aluminium, containing a coil 3 for heating or cooling and with other means such as a jacket, for the same purpose if desired. Air is admitted by a pipe 4 from a compressor 6. The cylinder 1 is supplied with hydrocarbon from a tank 14 through a pipe 7 and the oxidized products are withdrawn by a pipe' 8 and a gas outlet 9. In an example, a Pennsylvania crude oil of 42‹ BÚ. is employed with a manganese stearate catalyst at 120-140‹ C., air being admitted with the pipe 9 closed, until the desired pressure is reached, after which the tube 9 is opened sufficiently to maintain the pressure, which may be 250-300lb. The gases are discharged by the pipe 9 to a condenser to collect formic, acetic, and propionic acids. The oxidation so continued until the charge is practically wholly saponifiable. At the beginning of the process a part of the hydrocarbon mixture is oxidized to a product insoluble in the remaining oil and of acid nature. After removing this material, the process is continued. An acid aqueous liquid collects below the air-pipe 4 and is withdrawn from time to time. The product is a mixture of carboxylic, ketone-carboxylic, hydroxy-carboxylic, and ketohydroxy-carboxylic acids, which may be treated with a petroleum distillate to extract the simple carboxylic acids, or the mixture may be treated with strong sulphuric acid which dissolves the hydroxy and ketone acids but not the simple acids. The reaction product also contains non- acidic ketonic bodies which are separated in a separating-tank 12 and returned to the supply tank 14 as they dissolve oxygen and catalyze the reaction. The composition of the reaction product varies with that of the original material; from an oil from the Bradford field containing mainly normal paraffins the product is mainly solid. white carboxylic acids of high molecular weight resembling normal fatty acids; from oils from the lower Pennsylvania district containing a relatively large proportion of cyclic hydrocarbons the product contains hydroxy acids and acids derived from iso-paraffins which readily oxidizo to hydroxy-acids; and crude lower Pennsylvania lubricating oil which has been freed from wax and reduced to give a high viscosity and low cold test yields practically nothing but highly hydroxylated acids insoluble in petroleum, soluble in alcohol, and resembling shellac. The further the oxidation is carried, the higher is the proportion of hydroxy-acids produced. The insoluble substances produced at the beginning of the oxidation are produced from those constituents of the crude oil which may be removed from the crude oil by fuming sulphuric acid or liquid sulphur dioxide by the known refining methods. The products from a 42‹ BÚ. crude Pennsylvania oil are about 5 per cent formic acid, 5 per cent acids containing C7 to C12 and 90-95 per cent of acids having a molecular weight above 300 being liquid in the mixed state and of density greater than 1; from 30-35‹ BÚ. crude Pennsylvania oil 5 per cent of formic acid, 5 per cent of other volatile acids, and 95-100 per cent of acids of average molecular weight above 345, solid at 10‹ C. and of density less than 1; and from wax melting at 50-51‹ C. from crude Pennsylvania oil 5-10 per cent of formic acid, 5-10 per cent of other volatile acids, and 100-110 per cent of acids solid or semi-solid at ordinary temperature, melting at 45‹ C. and of density less than 1. Instead of a vertical cylinder, a rotary or stationary horizontal autoclave may be employed with suitable agitating means. Specifications 287,514 and 309,384 are referred to.