METHOD OF PRODUCING ESTERS OF FATTY ACIDS AND ETHANOL FROM FAT-CONTAINING WASTES Russian patent published in 2020 - IPC C07C67/03 C07C67/08 C11C3/04 C11C3/10 

FIELD: chemistry; technological processes.

SUBSTANCE: invention relates to processing of fat-containing vegetal origin (vegetable oils). Method involves a single-step operation involving combined acid-catalysed reactions of esterification of free fatty acids and re-esterification of triglycerides with ethanol to obtain ethyl esters of fatty acids. Reactions are carried out at temperature of 70–75 °C and using sulphuric acid as a catalyst, concentration thereof is set in range of 1.5–2 wt. %, with a weight ratio of triglycerides: alcohol of 1:6 to 1:10 and with content of water in ethanol to 3.8 wt. % Content of free fatty acids in the feedstock may vary from 0 to 40 wt. %. Reactions of esterification and re-esterification are carried out in one apparatus and in one step. Distinctive feature of the disclosed process is its carrying out in homogenised systems using mixtures of esters of alcohols and fatty acids as a homogenizer, which contain not less than 50 % of polyunsaturated hydrocarbon radicals with the number of double bonds of two or more. Combination of acid-catalysed esterification and re-esterification reactions in a homogenised system and their carrying out in one stage and in the same apparatus enables to reduce reaction time from 40–96 hours in systems without homogenisation to 12 hours and less in homogeneous conditions. Homogenisation agents used can be the esterification and re-esterification natural products - esters, and are introduced into the reagent mixture according to the recycling principle. Homogenizing capacity of esters depends to a great extent on the amount of double bonds in hydrocarbon radicals. As the number of double bonds in the hydrocarbon radicals of the ester increases, the amount required to form a homogeneous mixture of triglycerides and alcohol used as reagents is reduced.

EFFECT: homogenisation of the mixture of reagents eliminates the need for interphase transport of reagents and leads to elimination of diffusion limitations for the process of their interaction and, as a result, to reduction of reaction time from 40–96 hours according to prototype to 12 hours and less according to the proposed method.

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