Process for preparing fatty acid esters of short-chain monohydric alcohols
First Claim
1. In a process for preparing fatty acid esters and mixtures of fatty acid esters of short-chain monohydric alcohols having from 1 to 5 carbon atoms or short-chain diols having from 2 to 5 carbon atoms, which are monoalkylated by alkyl radicals having from 1 to 3 carbon atoms, by trans-esterification of fatty acid glycerides with the alcohols or monoalkylated diols in the presence of a basic catalyst, in a plurality of steps, the improvement which comprises:
- a) carrying out a trans-esterification in the presence of from 0.5% to 5.0% of a basic catalyst, based on the amount of fatty acid glyceride, and in the presence of a short-chain alcohol or monoalkylated diol in an excess over a stoichiometric quantity of from 10% to 200% per mol of glycerine-bound fatty acid; and
obtaining a relatively lighter fatty acid ester phase and a relatively heavier glycerine phase by settling and separating;
b) subjecting the relatively higher fatty acid ester phase obtained in step a) to transesterification in the presence of a basic catalyst and a short-chain alcohol or a monoalkylated diol;
c) adding at least one-tenth of the relatively heavier glycerine phase obtained in step a), while stirring; and
obtaining a fatty acid ester phase and a heavy glycerine phase by settling and separating;
d) removing excess short-chain alcohol or monoalkylated diol from the fatty acid ester phase obtained in step c, subsequently stirring in acid and, after a completed phase separation, removing the fatty acid ester phase.
0 Assignments
0 Petitions
Accused Products
Abstract
A process is disclosed for preparing fatty acid esters of short-chain monohydric aliphatic alcohols or monoalkylated diols by basically catalyzed esterification of natural, partially or totally synthetic fatty acid glycerides, as well as fatty acid glyceride-based waste products, such as used frying oils. The process is characterized in that the unpurified fatty acid glycerides, containing in particular high proportions of free fatty acids and phosphatides, (a) are esterified in one or several steps in the presence of a basic catalyst with an excess of short-chain alcohol or monoalkylated diol; (b) the glycerin phase produced after the first esterification step is at least partially added to the second or following step, after sterification has been carried out, and the mixture is stirred; (c) the glycerin phase is again separated, the supernatant fatty acid ester is cleared of excess alcohol or diol, then treated with a possibly diluted organic or anorganic acid, and if necessary filtered. This process, that is carried out without pressure and heat supply, is characterized by a technically simple implementation by means of simple equipment, and by a high degree of purity of the thus obtained fatty acid esters.
-
Citations
17 Claims
-
1. In a process for preparing fatty acid esters and mixtures of fatty acid esters of short-chain monohydric alcohols having from 1 to 5 carbon atoms or short-chain diols having from 2 to 5 carbon atoms, which are monoalkylated by alkyl radicals having from 1 to 3 carbon atoms, by trans-esterification of fatty acid glycerides with the alcohols or monoalkylated diols in the presence of a basic catalyst, in a plurality of steps, the improvement which comprises:
-
a) carrying out a trans-esterification in the presence of from 0.5% to 5.0% of a basic catalyst, based on the amount of fatty acid glyceride, and in the presence of a short-chain alcohol or monoalkylated diol in an excess over a stoichiometric quantity of from 10% to 200% per mol of glycerine-bound fatty acid; and
obtaining a relatively lighter fatty acid ester phase and a relatively heavier glycerine phase by settling and separating;b) subjecting the relatively higher fatty acid ester phase obtained in step a) to transesterification in the presence of a basic catalyst and a short-chain alcohol or a monoalkylated diol; c) adding at least one-tenth of the relatively heavier glycerine phase obtained in step a), while stirring; and
obtaining a fatty acid ester phase and a heavy glycerine phase by settling and separating;d) removing excess short-chain alcohol or monoalkylated diol from the fatty acid ester phase obtained in step c, subsequently stirring in acid and, after a completed phase separation, removing the fatty acid ester phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
Specification