GB612667A - Improvements in or relating to methods of alcoholysis of low grade fatty materials - Google Patents

Abstract

Low-grade fatty materials containing at least 5 per cent by weight of free fatty acid, for example dark coloured fatty oils, fats and greases, renderer's tallow and grease and kitchen waste grease, are subjected to alcoholysis with an alcohol having up to 3 carbon atoms in the molecule, the reaction being commenced in the presence of an acid alcoholysis catalyst and, when the free fatty acid content of the materials has been reduced to below 3 per cent by weight, continued in the presence of an alkaline alcoholysis catalyst. Thereupon, the reaction mixture is stratified, a layer containing crude alkyl esters of fatty acids is separated and the esters distilled off. Suitable acid alcoholysis catalysts are sulphuric, phosphoric and hydrochloric acids, sulphonic acids such as toluene sulphonic acid and camphor sulphonic acids, and metallic salts, while suitable alkaline alcoholysis catalysts are alkali metal alcoholates and caustic alkalis. The alcoholate may be prepared in situ from alkali metal and alcohol. Details of the recovery of alkyl esters, glycerol, unreacted alcohol, saponifiable materials and unsaponifiables are given and it is stated that the alkyl esters may be hydrogenated to improve their stability. In the examples, crude grease is reacted with methanol first in the presence of sulphuric acid and then in the presence of sodium methylate (produced by adding metallic sodium to the reaction mixture) or potassium carbonate.ALSO:Low grade fatty materials containing at least 5 per cent by weight of free fatty acid, for example dark coloured fatty oils, fats and greases, renderers tallow and grease and kitchen waste grease, are subjected to alcoholysis with an alcohol having up to 3 carbon atoms in the molecule, the reaction being commenced in the presence of an acid alcoholysis catalyst and, when the free fatty acid content of the materials has been reduced to below 3 per cent by weight, continued in the presence of an alkaline alcoholysis catalyst. Thereupon, the reaction mixture is stratified, a layer containing crude alkyl esters of fatty acids is separated and the esters distilled off. Suitable acid alcoholysis catalysts are sulphuric, phosphoric and hydrochloric acids, sulphonic acids such as toluene sulphonic acid and camphor sulphonic acids, and metallic salts, while suitable alkaline alcoholysis catalysts are alkali metal alcoholates and caustic alkalis. The alcoholate may be prepared in situ from alkali metal and alcohol. Details of the recovery of alkyl esters, glycerol, unreacted alcohol, saponifiable materials and unsaponifiables are given and it is stated that the alkyl esters may be hydrogenated to improve their stability. In the examples, crude grease is reacted with methanol first in the presence of sulphuric acid and then in the presence of sodium methylate (provided by adding metallic sodium to the reaction mixture) or potassium carbonate.