TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components:(a) contains 1-12C (preferably 1-5C). (b) is in the form of powder, extruded sections or beads, with a surface of 10-500 (preferably 30-400) m2/g, a porous volume of 0.1-1.2 (preferably higher than 0.2) cm3/g and a porous distribution of 0.01-0.1 microns.(b) is a transition metal catalyst of formulae ((ZnO)a(TiO2)b)y(Al2O3)1-y; (ZnaTibO(a+2b))y(Al2O3)1-y); or ((Bi2O3)a(TiO2)b)y(Al2O3)1-y (wherea and b = 0.5-5; and(MH#2) y = 0.005-1 (preferably 0.005-0.995)).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components:(a) contains 1-12C (preferably 1-5C). (b) is in the form of powder, extruded sections or beads, with a surface of 10-500 (preferably 30-400) m2/g, a porous volume of 0.1-1.2 (preferably higher than 0.2) cm3/g and a porous distribution of 0.01-0.1 microns.(b) is a transition metal catalyst of formulae ((ZnO)a(TiO2)b)y(Al2O3)1-y; (ZnaTibO(a+2b))y(Al2O3)1-y); or ((Bi2O3)a(TiO2)b)y(Al2O3)1-y (wherea and b = 0.5-5; and(MH#2) y = 0.005-1 (preferably 0.005-0.995)).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The reaction is carried out at 150-250degreesC under a pressure lower than 100 bar with an excess of (a) compared to stoichiometry oil/alcohol. The reaction is discontinuous.The reaction is continuous in a fixed-bed with autoclaves and decanters in series. The reaction is carried out in the fixed-bed with a volume of injected oil/volume of catalyst/hour 0.1-3 (preferably 0.3-2). The reaction comprises an initial transesterification with a conversion of oil into ester at 80-85%; evaporation of excess (a); decantation of glycerin and ester, recyclization of ester to undergo transesterification with part of the monoalcohol recovered in the first evaporation; and then evaporation of the monoalcohol, cold decantation and separation of glycerin and ester.The obtained ester is purified: by passing an earth and/or activated coal over a resin; or by distillation, washing with methanolic glycerin to reduce the content of monoglyceride. The obtained glycerin is purified after evaporation of alcohol by passing over a resin, a ground and/or activated carbon. The starting oil is an acid oil, in which the preliminary operation of glycerolysis is carried out by reacting free fatty acid with the catalyst, which is used for transesterification, at 180-220degreesC with a pressure equal or lower than 1 bar. To prepare ethyl ester, ethanol is mixed with methanol (1-50%). EXAMPLE - Colza oil (150 g) (containing palmitic acid (5 wt.%), palmitoleic acid (less than 0.5 wt.%), stearic acid (2 wt.%), oleic acid (59 wt.%), linoleic acid (21 wt.%), linoleic acid (9 wt.%), arachidic acid (less than 0.5 wt.%), gadoleic acid (1 wt.%), behenic acid (less than 0.5 wt.%), and erucic acid (less than 1 wt.%)); methanol (150 g); and catalyst (25 g) containing aluminum (14%), zinc (24%) and titanium (17%) were mixed. The reaction mixture was heated to 200degreesC for 8 hours under agitation, filtered and excess methanol was evaporated followed by elimination of glycerol formed by decantation. The reaction mixture was worked up to give the composition of the phase ester containing methyl esters (99.3%), monoglycerides (0.6%) and diglycerides (0.1%).