Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11C—FATTY ACIDS FROM FATS, OILS OR WAXES; CANDLES; FATS, OILS OR FATTY ACIDS BY CHEMICAL MODIFICATION OF FATS, OILS, OR FATTY ACIDS OBTAINED THEREFROM
  • C11C3/00—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom
  • C11C3/003—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom by esterification of fatty acids with alcohols
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11C—FATTY ACIDS FROM FATS, OILS OR WAXES; CANDLES; FATS, OILS OR FATTY ACIDS BY CHEMICAL MODIFICATION OF FATS, OILS, OR FATTY ACIDS OBTAINED THEREFROM
  • C11C3/00—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom
  • C11C3/04—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom by esterification of fats or fatty oils

Definitions

• the invention relates to an improved process for the preparation of esters of fatty acids or fatty acid mixtures and lower monofunctional alcohols by catalytic transesterification of fatty acid glycerides with the lower monofunctional alcohols in the presence of basic catalysts.
• the corresponding C, -4- alcohols are suitable as lower monofunctional alcohols, methanol being of decisive technical importance in practice.
• Fatty acid glycerides in the sense of the teaching according to the invention are corresponding triglycerides or any partial esters of fatty acids or fatty acid mixtures and glycerol. Of particular importance here are the triglycerides and, above all, fats and / or oils of native origin which can be converted into fatty acid methyl esters in a simple manner by the process according to the invention.
• Fatty acid methyl esters are of great technical importance as a starting material for the production of fatty alcohols and other oleochemical products such as ester sulfates, fatty acid alkanolamides and soaps.
• the industrial production of the fatty acid methyl esters takes place predominantly by catalytic transesterification (alcoholysis) of fatty acid triglyceride mixtures, as are present in the fats and oils of vegetable and / or animal origin.
• Such pre-esterification of acidic fatty acid glycerides can be carried out in several ways. For example, it is possible to work in the presence of alkaline catalysts from 240 ° C. and 20 bar (Ullmann, Encyclopedia of Industrial Chemistry, 4th edition, volume 11, 1976, page 432). However, this type of pre-esterification with methanol in turn requires the use of expensive reactors. It is also known to esterify the free fatty acids in the oil with added monofunctional lower alcohols, especially methanol, in a homogeneous phase by means of acid catalysis, for. B. using p-toluenesulfonic acid as a catalyst.
• a transesterification process is known in which anhydrous fatty acid glycerides are treated with an alcohol at elevated temperatures and in the presence of a transesterification catalyst, then the catalyst is removed in the cold, the excess alcohol is distilled off and finally the fatty acid ester obtained from the glycerol separates.
• the Ver used catalysts, sodium alkyl carbonates and sodium alkyl sulfites, are almost neutral and practically insoluble in the cold.
• the teaching of the present invention is based on the fact that fatty acid glycerides are reacted with lower monofunctional alcohols, in particular with methanol, with basic catalysis without problems under mild reaction conditions, in particular at ambient pressure, low temperatures and low use of methanol to give the corresponding alkyl esters and free glycerol can and that for the preconditions set here - low contents of the feed material in free fatty acids and water - there are sufficient practical possibilities of implementation.
• the inventors have set themselves the task of modifying this base-catalyzed transesterification of the fatty acid glycerides with monofunctional alcohols, in particular methanol, in such a way that solids which are practically insoluble in the feedstock or reaction mixture are used as catalysts - and thus with heterogeneous catalysis. It is obvious that considerable simplifications are obtained in this way, in particular when the catalyst is separated from the reaction mixture.
• the solution to the problem according to the invention is based on the surprising finding that solid sodium carbonate Na 2 CO 3 and / or sodium hydrogen carbonate NaHCO 3 are suitable as heterogeneous solid catalysts, the desired alcoholic cleavage of fatty acid glycerides under the mild conditions known per se, in particular of low pressures and temperatures catalyze effectively.
• the invention relates in a first embodiment to the use of solid sodium carbonate and / or sodium bicarbonate as heterogeneous solid catalysts in the transesterification of deacidified to an acid number of at most 1 and to a water content of at most 0.8% by weight of anhydrous fatty acid glycerides with im essential anhydrous monofunctional C '-4 alcohols to fatty acid alkyl esters and glycerol.
• the invention relates to a process for the catalytic transesterification of fatty acid glycerides, in particular fats and / or oils of natural origin, with monofunctional Cl-4-alkanols by reacting the acidified to an acid number of at most 1 and to a water content of at most 0.8 %
• anhydrous glyceride starting material with the essentially anhydrous alkanol in the presence of a catalyst which is practically insoluble in the cold, in the range from atmospheric pressure and moderately elevated temperatures above 60 ° C., preferably in the range of the boiling point of the alkanol, with subsequent separation of the glycerol released.
• the new process is characterized in that solid sodium carbonate and / or solid sodium bicarbonate is used as a heterogeneous solid catalyst.
• the process is carried out under energy-saving and cost-saving conditions in such a way that the fatty acid glyceride feedstock is reacted in the range of normal pressure and at only moderately elevated temperatures which do not substantially exceed the range of about 100.degree.
• the process temperature in the transesterification is preferably in the range of the boiling point of the alkanol used. Since work is carried out at normal pressure or only slightly elevated pressures, the reaction temperature for the transesterification of the glycerides with methanol is usually in the range from about 60 to 75 ° C., preferably in the range from about 65 to 70 ° C.
• Suitable fatty acid glycerides are in particular appropriately pretreated (deacidified) fats and / or oils of vegetable and / or animal origin. They are subjected to the transesterification with monofunctional alkanols with 1 to 4 carbon atoms. Methanol is preferably used as the lower alkanol.
• the glyceride feed material should have an acid number of at most 1, preferably acid number of at most 0.7, it being particularly expedient to work with acid numbers in the range of about 0.5 or less.
• the water content of the glyceride feed should be as low as possible; it is not more than about 0.8% by weight, it is preferred to work under practically anhydrous conditions. Deacidified and anhydrous glyceride feed material can easily be obtained as a reaction product of the upstream process stages described in the introduction - in particular as a product of a pre-esterification of the starting material.
• the reaction mixture uses weight ratios of alkanol - preferably methanol - to fatty acid glyceride in the range from 0.2 to 1: 1 and particularly preferably in the range from 0.2 to 0.5: 1.
• the heterogeneously catalyzed transesterification can be carried out batchwise or continuously.
• the catalyst can be either a finer or coarser powder, in Form of chips or tablets or as impregnation catalyst applied to a support material.
• the catalyst material can be arranged as a fixed bed, it is also possible to work with a moving bed of catalyst material, for example in stirred tanks, in a fluidized bed or fluidized bed in pulsation devices and the like. It is particularly expedient to carry out the heterogeneously catalyzed transesterification at normal pressure with low boiling point of the alcohol.
• the released glycerol is preferably separated from the reaction mixture by phase separation.
• it may be expedient to cool the reaction mixture or a partial stream branched off from the reaction mixture. It is advantageous to evaporate part of the monofunctional alcohol from the reaction mixture or from the branched-off partial stream of the reaction mixture before this cooling.
• the solubility of the released glycerol in the fatty acid ester / alcohol / oil phase is reduced and at the same time the density of the glycerol phase is increased, so that the resulting glycerol can be easily removed by phase separation.
• the alkanol drawn off from the reaction mixture in this way is preferably returned to the reactor in a circuit.
• the partial removal of the glycerol from the reaction mixture is carried out in such a way that when a partial stream, in particular continuously branched out of the reactor, is freed from the methanol and then separated from free glycerol, the methyl ester / oil phase returned to the reactor is a homogeneous liquid phase is, d. H. that neither a separate methanol phase nor a phase consisting of free glycerol occurs in the recirculated liquid phase.
• a particularly preferred embodiment of the invention consists in first passing at least a partial stream of the reactant mixture through an evaporator in which the free alkanol present is evaporated at least partially in the continuous process.
• the liquid phase is then cooled to temperatures below 50 ° C., in particular to temperatures in the range from 30 to 40 ° C., whereupon the heavier glycerol phase is separated and discharged by phase separation, while part of the lighter ester phase is recycled into the transesterification as a recycle stream the evaporated alkanol portion and fresh reactants are fed in simultaneously.
• the transesterification is carried out in several stages in a reactor cascade.
• the process according to the invention is particularly suitable as an important process step in the processing of natural in particular unpurified fats and / or oils such as coconut oil, palm kernel oil, soybean oil, tallow and the like. It is not necessary to clean these raw materials from the naturally contained sludge and mucilage.
• the natural starting material is first subjected to pre-esterification as described at the beginning.
• the process carried out with solid cation exchange resins according to the applicant's older EP-A-192 035 is particularly suitable here.
• the material obtained in this preliminary stage with acid numbers preferably below 0.7 contains, in addition to methanol, the excess from the pre-esterification also water components which can be partially or completely expelled as a mixture.
• the proportion of bound glycerol in the methyl ester phase after the glycerol separation was approximately 0.5% by weight. The values were reproducible over several days without changing the catalyst.

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• 1985
  • 1985-04-29 DE DE19853515403 patent/DE3515403A1/de not_active Withdrawn
• 1986
  • 1986-04-10 GB GB08608680A patent/GB2174697B/en not_active Expired
  • 1986-04-21 EP EP86105506A patent/EP0200982B1/de not_active Expired
  • 1986-04-21 DE DE8686105506T patent/DE3661737D1/de not_active Expired
  • 1986-04-21 AT AT86105506T patent/ATE39947T1/de not_active IP Right Cessation
  • 1986-04-28 BR BR8601882A patent/BR8601882A/pt unknown
  • 1986-04-28 PH PH33709A patent/PH23503A/en unknown
  • 1986-04-30 JP JP61100818A patent/JPS61254255A/ja active Pending

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