BRPI1004843A2 - catalyst system for biodiesel production - Google Patents

Abstract

CATALYST SYSTEM FOR BIODIESEL PRODUCTION. The present invention relates to the use of a catalyst system comprising a transesterification catalyst selected from the group of alkali metal or alkaline earth metal alkanolates in one or more organic solvents, the transesterification catalyst content being 1 to 10%. by weight in relation to the catalyst system for catalysis of transesterification reactions.

Description

Patent Descriptive Report for "CATALYST SYSTEM FOR BIODIESEL PRODUCTION".

The present invention relates to the use of a catalyst system comprising a transesterification catalyst selected from the group of alkali metal or alkaline earth metal alkanolates in one or more organic solvents, the content of transesterification catalysts being 1 to 10% by weight relative to the catalyst system for catalysis of transesterification reactions.

Fatty acid alkylesters of monovalent alcohols have for some time been found to be of important use in use as biodiesel, a substitute for fossil diesel, based on renewable raw materials.

Biodiesel production is usually done by base-catalyzed transesterification (The Biodiesel Handbook, G.Knothe, J. van Gerpen, J.Krahl, Ed. AOCS Press (2005); Biodiesel - The Comprehensive Handbook, M. Mittelbach, C. Remschmidt (2004); Bioresource Technology 2004, 92, 297; Applied Energy 2010, 87, 1083; Chimica Oggi / Chemistry today 2008, 26).

The most commonly used catalysts are sodium methanate (NaOMe), sodium hydroxide (NaOH), potassium methanolate (KOMe) and potassium hydroxide (KOH). These catalysts are generally employed as homogeneous catalysts dissolved in alcohol such as methanol. Alkanolate solutions have alkanolate contents of at least 20 wt%, usually around 30 wt%. This alkanolate concentration is clearly very high for biodiesel production. For this reason, the dosage of these solutions needs to be very accurate, which is technically more difficult to accomplish. Oscillations caused by the process can only be compensated for very difficultly as minor oscillations are usually overcompensated by the addition of the alkanolate solution as it cannot be added accurately enough.

In the use of NaOH as a catalyst, catalyst solution often forms from the solid and a solvent, which means an additional and more difficult to react expenditure.

The task of the present invention was therefore to provide a simplified process for transesterification of glycerides with monovalent alcohols.

The present task is solved within the scope of the present invention by the fact that the catalyst system contains the complete amount of alkanate and monovalent alcohol which will be chemically reacted. With this, the conduction of the reaction is clearly simplified, which improves the overall process. In addition, the costs are reduced for biodiesel manufacturers as they no longer have to provide for any prior adaptation of the catalyst system. The catalyst system of the present invention may be used without further modification directly in the transesterification reaction.

Using the catalyst system of the present invention the biodiesel producer only needs to add two more liquids to the biodiesel production, namely the oil to be employed and the catalyst system, whereas in current processes they must be added by minus three liquids (oil, MeOH and highly concentrated alkanolate solution). This leads to simplification of work, fewer sources of error arise and fewer reservoir tanks are required, leading to reduced production and investment costs.

In addition, alkanolate solutions at higher concentrations, such as sodium methylate, need to be stored at temperatures above 10 ° C as otherwise sodium methylate crystallizes and therefore cannot the right amount of catalyst to be added to the biodiesel reaction. This leads to fluctuations in production, ie the reaction becomes slower due to excessively low catalyst concentrations. This is not the case in the catalyst systems according to the invention.

Therefore, a first object of the present invention is the use of a catalyst system comprising a transesterification catalyst selected from the alkali metal or alkaline earth metal alkanolate group in one or more organic solvents, with the catalyst content of Transesterification is 1 to 10% by weight of the catalyst system for catalyzing transesterification reactions.

The catalyst system employed according to the invention has two components: the transesterification catalyst and one or more organic solvents.

The transesterification catalyst is responsible for the transesterification itself and is chosen from the group of alkaline or alkaline earth metal alkanolates. Preferred transesterification catalysts are sodium methanolate, potassium methanolate, sodium ethanolate, potassium ethanate and / or mixtures thereof. Most particularly preferably sodium methanolate or potassium methanolate are used as transesterification catalysts.

Preferably one or more solvents are alcohols, preferably methanol and / or ethanol. Most particularly preferably the alcohol employed corresponds to the alkanolate employed. Thus, particularly sodium methanolate in methanol or potassium methanolate in methanol is employed as a catalyst system. It is also basically possible to use other solvents, but alcohols have been particularly advantageous.

The content of the transesterification catalyst is 1 to 10% by weight.

preferably 2-6% by weight with respect to the catalyst system. Particularly the range especially chosen for the transesterification catalyst content is responsible for the advantageous effects of the present invention. In this way the disadvantages of known catalyst systems are avoided and processing is considerably simplified.

The mentioned catalyst systems are suitable for use in transesterification reactions, and there are basically no restrictions on the type of transesterification reaction. By transesterification reaction within the meaning of the present invention is meant a reaction in which an educt ester and an alcohol are reacted together in the presence of the catalyst system, such that the alcohol reacts with the educt ester acid to a corresponding novel agent. product ester. Therefore, the ester employed is cleaved and the acid thus released is esterified with the added alcohol. The catalyst system is preferably employed for the production of fatty acid alkyl esters by transesterification of mono-, di- or triglycerides. Thus, mono-, di- or triglycerides are transformed into the corresponding fatty acid alkyl esters and simultaneously free glycerin is obtained.

Another object of the present invention is therefore a process for the preparation of fatty acid alkyl esters comprising the transesterification of at least one mono-, di- or triglyceride in the presence of at least one monovalent alcohol, whereby for catalysis A catalyst system comprising a transesterification catalyst chosen from the group of alkali metal or alkaline earth metal alkanolates in one or more organic solvents is used, the transesterification catalyst content being 1 to 10% by weight to the catalyst system.

The catalyst systems to be employed have already been cited

above.

Starting materials for the process according to the invention are mono-, di- and triglycerides of the general formula (I)

H2C-O-X

I

HC-O-Y

H2C-O-COR®

where X = COR1 or Η, Y = COR2 or H and R11 R2 and R3 which may be the same or different means aliphatic hydrocarbon groups of 3 to 23 carbon atoms and these groups may optionally be substituted with an OH group or desired mixtures of such glycerides. Thus, in glycerides according to formula (I), one or two fatty acid esters may be substituted for hydrogen. The fatty acid esters R1CO-, R2CO- and R3CO- are derived from fatty acids with 3 to 23 carbon atoms in the alkyl chain. R1 and R2 or R1, R2 and R3 in the above formula may be the same or different when dealing with di- or triglycerides. The radicals R11 R2 and R3 belong to the following groups:

a) alkyl radicals, which may be branched, but are preferably straight chain and have 3 to 23, preferably 7 to 23 carbon atoms.

b) olefinically unsaturated aliphatic hydrocarbon radicals which may be branched but are preferably straight chain and have 3 to 23, preferably 11 to 21 and particularly 15 to 21 carbon atoms and containing 1 to 6, preferably 1 up to 3 double bonds, which may be conjugated or isolated;

c) substituted monohydroxy radicals of type a) and b), preferably unsaturated olefin radicals having 1 to 3 double bonds, particularly the ricinoleic acid radical.

The acyl radicals R1CO-, R2CO- and R3CO of such glycerides which are suitable as starting materials for the process of the present invention are derived from the following aliphatic carboxylic acid (fatty acid) groups:

(a) alkanoic acids or their particularly branched alkyl-branched alkyl derivatives having from 3 to 24 carbon atoms such as butyric acid, valeric acid, caproic acid, hepanoic acid, caprylic acid, pelargonic acid , capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, stearic acid, nonadecanoic acid, arachidinic acid, behenic acid, lignoceric acid, 2-methyl butanoic acid, acid - of isobutyric acid, isovaleric acid, pivalic acid, isocaproic acid, 2-ethylcaproic acid, the position isomers methyl capric acids, methyl tripuric acids and methyl stearic acids, 12-hexyl stearic acid, isostearic acid or 3,3-dimethylstearic acid.

(b) alkenic acids, alkadiic acids, alkatrienic acids, alkatetraenic acids, alcapentaenic acids and alkhexaenic acids as well as their alkylamid derivatives, especially methyl branched derivatives of 3 to 24 carbon atoms, such as chromic acid, isochrotonic acid , caproleic acid, 3-lauroleic acid, myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, erucic acid, brassidic acid, 2,4-decadienic acid, linoleic acid, 11,14-eicosadienic acid, eleosteic acid, linolenic acid, pseudoheosteic acid, arachidonic acid, 4, 8, 12, 15, 18, 21-tetracosahexaenoic acid or trans-2-methyl-2-butenic acid.

C1) monohydroxyalkanoic acids having 3 to 24 carbon atoms, preferably 12 to 24 carbon atoms, preferably unbranched, such as hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, 2-hydroxydodecanoic acid, 2 - hydroxytetradecanoic acid, 15-hydroxypentadecanoic acid, 16-hydroxyhexadecanoic acid, hydroxyoctadecanoic acid,

c2) furthermore, 3 to 24 monohydroxyalkenoic acids, preferably 12 to 22 and particularly 16 to 22 carbon atoms (preferably unbranched) and 1 to 6, preferably 1 to 3 and particularly with an ethylenic double bond, such as ricinoleic acid or ricinelaidic acid.

Preferred starting substances for the process according to the invention are, in particular, natural greases, which represent predominantly mixtures of triglycerides and small fractions of diglycerides and / or monoglycerides, and also these glycerides, on the other hand, also represent mixtures and contain fatty acid radicals of different types within the aforementioned scope, particularly those having 8 and more carbon atoms. As an example, vegetable fats such as olive oil, coconut fat, palm kernel oil, babassu oil, palm oil, peanut oil, rapeseed oil, castor oil, sesame oil, Jatropha, sunflower oil, soybean oil, hemp oil, poppy oil, avocado oil, cottonseed oil, wheat germ oil, corn germ oil, pumpkin seed, grape seed oil, cocoa butter or also vegetable fats, in addition to animal fats such as beef tallow, pork fat, bone fat, mutton tallow, Japantalg wax, whale and other fish oils as well as cod liver oil. Homogeneous tri-, di- and monoglycerides may also be used provided they have been isolated from natural fats or obtained synthetically. Examples are mentioned here: tributyrin, tricapronine, tricapriline, tricaprinine, trilaurin, trimiristine, tryristin, tristearine, triolein, trielaidine, trilinoliine, trilinolenin, monopalmitine, monostearin, monoleole, monocaurine or monocaurine, for example palmitodiestearin, distearoolein, dipalmitoolein or myristopalmititeearin.

Under monovalent alcohols within the meaning of the present invention are meant alcohols having only one OH group. Examples for modern alcohols are methanol, ethanol, n-propanol, isopropanol and n-butanol, isobutanol, sec-butanol or tert-butanol as well as branched or long chain alcohols, optionally also branched alcohols such as for example amyl alcohol, tert-amyl alcohol, n-hexanol and / or 2-ethyl hexanol. Preferably methanol and ethanol are employed. Said alcohols may be employed alone or in admixture in the process according to the invention.

The concentration of the transesterification catalyst is 0.001-20 wt%, preferably 0.01-5 wt% and particularly preferably 0.1-2 wt% over the amount of mono-, di- or triglycerides employed.

The process according to the invention may be performed by any means known to the person skilled in the art. In carrying out the process according to the invention the reaction mixture is preferably stirred. Preferred intensive mixing of the reaction mixture may also be achieved by other methods known to the skilled artisan.

The reaction time may last up to 4 hours, preferably from 1 to 120 minutes is chosen. This achieves conversion rates of at least 98%, preferably at least 99%. The degree of reaction conversion refers to the glyceride fraction (= sum of tri-, di- and monoglycerides) still present after the termination or interruption of the reaction in relation to the initial content of these components in the oil or grease employed. The degree of conversion can be determined simply by gas chromatography and is calculated by the alkylester contents divided by the sum of the alkylest glyceride contents.

The fatty acid alkyl esters obtainable by the process of

according to the invention may be employed as biodiesel. According to DIN EN 14214, biodiesel should only contain a maximum of 0.2% triglycerides according to the test method PR EN 14105. In traditional transesterification processes which employ equimolar amounts of NaOH1 only after a longer period of time are obtained degrees of hydrogen peroxide. conversion in the order of magnitude> 99.8%.

The process according to the invention may be conducted continuously or in batches (for example, in a pipe reactor, agitator boiler, stirring boiler cascade, or other processes known to the artisan).

The process can be carried out in single or multiple steps, preferably a 2-step execution is employed.

In the process according to the invention preferably a molar ratio (monovalent alcohol: mono-, di-, triglyceride) in the range from 3: 1 to 20: 1 is adjusted. A ratio of 4: 1 to 8: 1 is therefore particularly preferred.

Transesterification is carried out over a temperature range of 0 - 200 ° C, preferably 10 - 100 ° C and particularly preferably at 20 - 80 ° C.

Here transesterification is carried out at a pressure range of

0.01 Mpa - 10Mpa (0.1 - 100 bar), preferably 0.005Mpa - 5Mpa (0.5 - 50 bar) and most particularly preferably 0.1 - 0.5Mpa (1-5 bar).

The catalyst system is mixed with mono-, di- or triglyceride and optionally additionally monovalent alcohol, whereby monovalent alcohol is consumed and glycerin is released. Essential is that the total catalyst system, ie the transesterification catalyst and the alcohol to be preferably employed, are present as a mixture at the beginning of the transesterification reaction.

The reaction mixture may be processed in different ways. After transesterification to the desired degree of conversion, preferably up to 98% or more, as a rule an alkylester phase of the fatty acid and a glycerine phase can be easily separated by the technician in stages. known procedural procedures, such as settling. By the catalyst system according to the invention, phase separation is accelerated, which greatly facilitates processing.

Another object of the invention is the use of the fatty acid alkylester obtainable according to the invention as a biodiesel component (eg according to DIN EN 14214).

Also without further explanation, it is assumed that a technician may use the above description in its broadest sense. Preferred embodiments and examples should therefore be considered a purely descriptive, by no means limiting disclosure form.

In the following, the present invention is further elucidated in light of the examples. Alternative embodiments of the present invention are obtained analogously. Examples:

Example 1: NM30 2-Step Transesterification (Comparison Example)

300 g rapeseed oil (acidity index = 0,1 mg KOH / g; 0,05% water) is first placed in a double-cloaked container with 30 g methanol at 60 ° C and then mixed under stirring with 4.2 g of NM30 (30% sodium methanolate in methanol, 1.4% by weight). The reaction mixture is then stirred for 2 hours at constant temperature (60 ° C). Then the reaction mixture is drained into a separatory funnel and the upper phase of biodiesel is separated from the lower phase of glycerine. The biodiesel phase is returned to the double-shell container mixed with 10 g MeOH and then 1.8 g NM30 (0.6% NM30; NM30 total = 2.0%). Then the reaction mixture is stirred for 2 hours at 60 ° C and then returned to the separatory funnel for phase separation. The upper crude biodiesel phase is washed once with 100 g of dilute aqueous hydrochloric acid and then washed twice, each time with 100 g of warm distilled water at 60 ° C and finally dried for one hour at 2Kpa (20 mbar). and 90 ° C. 297 g of biodiesel are obtained according to the specifications according to EN 14214, with the following parameters:

free glycerin: <0.01%

monoglycerides: 0.42%

diglycerides: 0.13%

triglycerides: <0.1%

FAME: 98.7%

Example 2: 1-Step Transesterification with NM30 (Comparison Example)

300 g rapeseed oil (acidity index = 0.1 mg KOH / g; 0.05% water) is placed in a double-cloaked container with 56 g methanol at 60 ° C and then mixed under stirring with 6 g. 1.0 g of NM30 (30% sodium methanolate in methanol, 2.0% by weight). The reaction mixture is then stirred for 4 hours at constant temperature (60 ° C). Then the reaction mixture is drained into a separatory funnel and the upper phase of biodiesel is separated from the lower phase of glycerine. The upper phase of crude biodiesel is washed once with 100 g of dilute aqueous hydrochloric acid and then washed twice, each time with 100 g of warm distilled water at 60 ° C and finally dried for one hour at 2 Kpa ( 20 mbar) and 90 ° C. 292 g of biodiesel are obtained according to the specifications according to EN 14214, with the following parameters:

free glycerin: <0.01%

monoglycerides: 0.65%

diglycerides: 0.18%

triglycerides: 0.1%

FAME: 97.4%

Example 3: Two-step transesterification according to the invention 300 g rapeseed oil (acidity index = 0.1 mg KOH / g; 0.05% water) is mixed at 60 ° C in the first step, in a 34.2 g double-cloaked container of 3.7% sodium methanolate solution. The reaction mixture is then stirred for 2 hours at constant temperature (60 ° C). Then the reaction mixture is drained into a separatory funnel and the upper biodiesel phase is separated from the lower glycerine phase. The biodiesel phase is returned to the double-cloaked vessel and mixed with 11.8 g of a 3.7% sodium methanolate methanol solution at 60 ° C. Then the reaction mixture is stirred for 2 hours at 60 ° C. It is then returned to the separating funnel for phase separation. The upper phase of crude biodiesel is washed once with 100 g of dilute aqueous hydrochloric acid and then washed twice, each time with 100 g of warm distilled water at 60 ° C and finally dried for one hour at 2Kpa (20 mbar ) and 90 ° C. 295 g of biodiesel are obtained according to the specifications according to EN 14214, with the following parameters:

free glycerin: <0.01% monoglycerides: 0.58% diglycerides: 0.17%

triglycerides: 0.1%

FAME: 98.1%

Example 4: One-step transesterification according to the invention 300 g rapeseed oil (acidity index = 0.1 mg KOH / g; 0.05% water) is mixed in a 62 g double cloak container of a 2.9% methanolic sodium methanolate solution at 60 ° C and then stirred for 4 hours at constant temperature (60 ° C). Then the reaction mixture is drained into a separatory funnel and the upper phase of biodiesel is separated from the lower phase of glycerine. The upper phase of crude biodiesel is washed once with 100 g of dilute aqueous hydrochloric acid and then washed twice, each time with 100 g of warm distilled water at 60 ° C and finally dried for one hour at 2Kpa ( 20 mbar) and 90 ° C. 296 g of biodiesel are obtained according to the specifications according to EN 14214, with the following parameters:

free glycerin: <0.01% monoglycerides: 0.52% diglycerides: 0.15%

triglycerides: <0.1%

FAME: 98.5%

The above examples show that biodiesel production can be simplified with the catalyst system according to the invention, because the addition of solvents required in traditional processes ceases to exist without restrictions on the quality of biodiesel. The advantages of the catalyst system according to the invention become particularly apparent in two-step transesterification, as mixing of additional solvents in each additional step is no longer required.

15

Claims (12)

1. Use of a catalyst system comprising a transesterification catalyst selected from the group of alkali metal or alkaline earth metal alkanolates in one or more organic solvents, the transesterification catalyst content being 1 to 10% by weight with respect to catalyst system for catalysis of transesterification reactions. Use according to claim 1, characterized in that the transesterification catalyst is chosen from sodium methanolate, potassium methanolate, sodium ethanolate, potassium ethanolate and / or mixtures thereof. Use according to claim 1 or 2, characterized in that the solvent is chosen from methanol, ethanol or mixtures thereof. Use according to any one of claims 1 to 3, characterized in that the catalyst system is employed for the preparation of fatty acid alkyl esters by transesterification of mono-, di- or triglycerides. Use according to any one of claims 1 to 4, characterized in that the content of the transesterification catalyst is 2 to 6% by weight relative to the catalyst system. Process for the preparation of fatty acid alkyl esters comprising the transesterification of at least one mono-, di- or triglyceride in the presence of at least one monovalent alcohol characterized by the fact that for catalysis a catalyst system comprising a transesterification catalyst selected from the group of alkali metal or alkaline earth alkanoates in one or more organic solvents, the transesterification catalyst content being 1 to 10% by weight relative to the catalyst system. Process according to Claim 6, characterized in that the transesterification catalyst is chosen from sodium methanolate, potassium methanolate, sodium ethanolate, potassium ethanolate and / or a mixture thereof. Process according to Claim 6 or 7, characterized in that the concentration of the transesterification catalyst is 0.001 - 20% by weight relative to the amount of mono-, di- or triglycerides employed. Process according to any one of Claims 6 to 8, characterized in that the transesterification is carried out within a temperature range of 0 to 200 ° C. Process according to any one of claims 6 to 9, characterized in that the transesterification is carried out within a pressure range of 0.1 - 0.5 MPa (1-5 bar). Process according to any one of claims 6 to 10, characterized in that methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, amylalcohol as monovalent alcohol are employed. n-hexanol and / or 2-ethylhexanol. Use of the fatty acid alkylester prepared according to the process as defined in any one of claims 6 to 11, as a biodiesel component.