Abstract: In order to produce a composition of esters of linear monocarboxylic acids containing 6 to 26 carbon atoms and glycerine simultaneously with high degrees of purity, the following is carried out:a step a) in which a plant or animal oil, which may or may not be acidic, is reacted with an excess of at least one aliphatic mono-alcohol containing 1 to 4 carbon atoms in the presence of a heterogeneous catalyst, eliminating the excess mono-alcohol and separating out glycerine, this step producing a crude ester containing residual mono-glycerides;a step b) in which the crude ester obtained undergoes transesterification or esterification of the residual mono-glycerides to di- and tri-glycerides, in the presence of a heterogeneous catalyst; anda step c) in which the ester composition is evaporated under reduced pressure, recycling the evaporation residue to the starting oil of step a). The ester compositions obtained, which are of high purity, are of particular use as gas oil substitutes.

Abstract: For the production of linear monocarboxylic acid esters with 6 to 26 carbon atoms vegetable oils or animal oils, which may or may not be neutral, are reacted with monoalcohols having a low molecular weight, for example 1 to 5 carbon atoms, in the presence of a catalyst that is selected from among zinc oxide, mixtures of zinc oxide and aluminum oxide, and the zinc aluminates that correspond to the formula:ZnAl.sub.2 O.sub.4, x ZnO, y Al.sub.2 O.sub.3(with x and y each being in the range of 0-2) and having more particularly a spinel type structure, thereby enabling the direct production in one or more stages, of an ester that can be used as a fuel or combustible and a pure glycerine.

Abstract: A description is given of an improved process for the production of esters from fatty substances having a natural origin (animal and vegetable oils) and low molecular weight alcohols, in which the soaps and oily compounds entrained in the alkaline phases are recycled by treating them, following acidification and separation, with a fraction of the glycerol phase produced, in the presence of an alkaline catalyst and for forming preferably a triglyceride or a partly substituted glyceride.This process makes it possible to quantitatively obtain methyl, ethyl, propyl or butyl esters usable as a substitute for gas oil.