FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICA TION
(See section 10, rule 13)
/. Title of the invention
A PROCESS FOR PRODUCTION OF BIOLUBRICANT USING FLY ASH AS A CATALYST
2. Applicant(s)
Name Nationality Address
[ATA CHEMICALS LTD.. INDIA BOMBAY HOUSE-:, 24 IIOMI MODI STREET. MUMBAI-400001


3. Preamble to the description
COMPLETE SPECIFICA TION
The following specification particularly describes the invention and the manner in which it is
to be performed.

The following disclosure generally relates to a process for production of alkyl esters. More particularly, the disclosure relates to a process for production of fatty acid alkyl esters useful in biolubricants by esterification and/or transesterification reaction using fly ash as a catalyst.
BACKGROUND
Biolubricants are essentially fatty acid alkyl esters, with the alkyl chain usually higher than a C5 unit. This finished product derived from renewable raw material such as animal fats and vegetable oils is a biodegradable and a non-toxic alternative to synthetic lubricants. Apart from its use in automobile industry, biolubricants are also used in the manufacture of cosmetics, feedstuff's, soaps etc.
Conversion of lipids to biolubricant involves the initial reaction where ester linkages of the fatty acids with glycerol are broken to form corresponding fatty acids and glycerol. The free fatty acids are in the subsequent step converted into fatty acid alkyl (e.g., hexyl, heptyl, 2 ethyl hexyl, octyl, decyl and their respective isomers) esters using alkanol (e.g., hexanol, heptanol, 2 ethyl hexanol, octanol, decanol and their respective isomers) as the reactant. The total process is termed as transesterification and the final products of the reaction are biolubricant and glycerol. Such transesterification reaction can be catalyzed both by acids and bases.
Existing technology for transesterification processes uses homogeneous alkali catalyst such as NaOH or KOH. While the homogeneity of the reaction mass enhances the conversion rate, the catalyst is part of the reaction product. This makes it necessary to carry out a complicated step of separation and/or removal of the catalyst. The process of separating biolubricants from catalyst and glycerol involves a neutralization process with strong acids (e.g., MCI), and extensive washes with water to remove the resulting sodium salt. Further, in order to
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remove sodium chloride from glycerol and to obtain glycerol in high purity, distillation of high boiling glycerol has to be carried out which is an energy intensive operation.
The use of alkali catalyst also cause saponification of free fatty acids contained in fats and oils to form soaps as by products, whereby it becomes necessary to carry out a step of washing with large amounts of water. In addition, the yield of alkyl esters decreases due to the emulsification effect of the soaps generated and, in certain instances, the subsequent glycerine purification process also becomes complicated. In order to overcome the problem associated with free fatty acids, a strong homogeneous acid like sulphuric acid is generally used along with the reactant alcohol (e.g., methanol) as a pre-treatment catalyst that converts free fatty acids to alkyl esters. However, if acid is used in the pre-treatment process, neutralization of oil has to done before transesterification reaction may be carried out. This further creates economical and environmental concerns.
In order to overcome the problems associated with use of a homogeneous catalyst, heterogenous solid catalysts for the transesterification of oils to alkyl esters have been developed. For example, various basic metal oxides, such as magnesium methoxide, calcium oxide, calcium alkoxide, and barium hydroxide, have been demonstrated to be active catalysts for transesterification.
However, the recyclability of these solid base catalysts is poor. This is because of the. moderate solubility of some of these solid metal oxides, hydroxides and alkoxides in methanol/ethanol and strong physical adsorption of the reaction products on their surfaces.
Use of double metal cyanides and metal (e.g., Zn, Mo) embedded on supports (like alumina) as recyclable solid catalysts have also been claimed recently. The major drawback of such a catalyst is its relatively higher cost of preparation and therefore requiring large number of
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recycles. These recovery and further activation for recycling of catalyst cause technical and economic restrains.
In view of these drawbacks, there is a need to develop a process for production of alkyl esters useful as biolubricants that does not require tedious aqueous washes and neutralization steps. An economical and recyclable catalyst that can be easily separated from the alkyl ester products for the conversion of oils to biolubricants is also needed. Moreover a catalyst that can economically catalyse both the esterification of free fatty acids and transesterify oils to alkyl esters useful as biolubricants is desirable.
SUMMARY
The invention relates to a process for production of alkyl esters. The process includes reacting a feedstock that includes one or more fatty acid glycerol esters or one or more fatty acids or mixture thereof with a C5 to C12 alcohol in the presence of fly ash as a catalyst.
The invention also relates to a catalyst composite material for the production of alkyl esters having a C5 to C12 alkyl chain from a feedstock including one or more fatty acid glycerol esters or one or more fatty acids or mixture thereof, wherein the catalyst includes fly ash.
DETAILED DESCRIPTION
To promote an understanding of the principles of the invention, reference will be made to the embodiment and specific language will be used to describe the same. It will nevertheless be understood that no limitation of scope of the invention is thereby intended, such alterations and further modifications in the illustrated process and such further applications of the principles of.
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the inventions as illustrated therein being contemplated as would normally occur to one skilled in art to which the invention relates.
A method for the production of alkyl esters is described. More particularly, a method of production of alkyl esters from a fatty acid containing feedstock using fly ash as a catalyst is described. Fly ash is generally defined as finely divided residue resulting from the combustion of powdered coal transported from the firebox through the boiler by the flue gases. The composition of the fly-ash is found to vary on the type of coal used. However, the composition of the fly ash may have the following composition by weight percentage 5 to 12 SiO2, 2 to 11 A12O3, 0.50 to 2.0 Fe203, 35 to 60 CaO, 0.40 to 1 MgO and 26 to 30 SO3.
The process for production of alkyl esters comprises reacting a feedstock that includes one or more fatty acid glycerol esters or one or more fatty acids or mixture thereof with an alcohol in the presence of fly ash as a catalyst to get a reaction mixture comprising a mixture of alkyl esters, alcohol and fly ash and recovering alkyl esters from the reaction mixture.
Fly ash used in the process catalyzes transesterification of the fatty acid glycerol esters present in the feedstock as illustrated in the exemplified reaction below:

The fly ash also catalyzes the esterification of fatty acids present in the feedstock as illustrated in the exemplified reaction

1-30 weight percentage of fly ash with respect to the fatty acid starting material may be used as a catalyst for the reaction. The molar ratio of the feedstock to alcohol may be in the range of 3 to 60, preferably in the range of 6 to 30 and most preferably in the range of 7.5 to 15.
A greater than 98% conversion is achieved by the process and a greater than 99% conversion is achieved using fly ash as a catalyst under preferred reaction condition.
Fly ash is easily recovered from the reaction mixture by any method including gravitational settling, filtration, centrifugation or any combination thereof.
In accordance with an aspect, once separated, the fly ash may be reused, if needed, as a catalyst for production of alkyl esters without any loss of catalytic activity. The recyclability has been tested for at least five cycles and the reaction proceeds with quantitative yield of the products.
In accordance with an aspect, the fly ash recovered from the reaction mixture may be washed and dried prior to reusing it as a catalyst for the production of alkyl esters. The fly ash recovered from the reaction mixture may be washed with any organic solvent in which the organics are soluble. In accordance with an aspect, hydroxylated solvents for example alcohols such as methanol and ethanol are used but less polar organic solvents like hydrocarbons (e.g., hexane) may also be used to selectively remove the alkyl esters. Glycerine left behind with the catalyst may be extracted with water or a hydroxylated solvent. Chlorinated solvents such as chloroform, dichloromethane may also be used.
The reaction mixture includes an upper layer containing fatty acid alkyl esters and alcohol and a lower layer containing glycerol and alcohol. Recovery of alkyl esters from the reaction mixture is carried out by separating the catalyst from the reaction mixture. The alkyl
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esters are recovered from the upper layer and separated from the glycerol rich lower layer and alcohol is removed from the two layers. Alternatively, methanol can be distilled off by simply de-pressuring the reactor at the reaction temperature leaving behind two immiscible liquids in fatty acid alkyl ester and glycerol along with the solid catalyst.
In accordance with an aspect, the production of alkyl esters comprises of reacting a feedstock that includes one or more fatty acid glycerol esters or one or more fatty acids or mixture thereof with an alcohol in the presence of fly ash as a catalyst at an elevated temperature and auto generated pressure for a predetermined period of time to get a reaction mixture, the reaction mixture contains a mixture of alkyl esters, glycerol, alcohol and fly ash; removing the fly ash catalyst from the said reaction mixture by filtration or any suitable conventional separation method to get a liquid with two phases, an alcohol containing alkyl esters rich upper layer and alcohol containing glycerol rich lower layer, separating the two phases and removing the alcohol from alkyl esters and glycerol rich liquids by conventional distillation to get alkyl esters and glycerol.
The feed stock used for this process may contain free fatty acids or fatty acid glycerol esters or their mixture thereof. The fatty acid glycerol ester may be mono-, di- or tri-ester of glycerol with varying degree of unsaturation in the fatty acid chain. The feedstock used for the production of alkyl esters may be any fatty acid rich material including but not limited to vegetable oil, used vegetable oil, restaurant waste grease, acid oil or surplus liquid or solid fats such as vegetable shortening, surplus margarine or animal fats. Each of these may be used individually or as a mixture.
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In accordance with an aspect, additional processing such as removal of excess water or filtering out of precipitate may be required before using animal fat or vegetable oil for this process.
The alcohol to be used for the reaction may be any C 5 - C12 alcohol, including but not limited to pentanol, hexanol, heptanol, 2-ethyl hexanol, octanol, decanol, undecanol or dodecanol. The alcohol used may be primary, secondary or tertiary in nature. Single alcohol or a mixture of two or more alcohols may also be used for the reaction.
In accordance with an aspect, the reaction is carried out at an elevated temperature of 120-250°C under autogenerated pressures.
In accordance with an aspect, the alcohol containing alkyl ester rich upper layer may be separated from the alcohol containing glycerol rich lower layer by any method including but not limited to gravitational settling, centrifugation and distillation using separation funnel or a combination thereof. In accordance with an embodiment alcohol is removed from alkyl esters and glycerol by vacuum distillation.
A catalyst composite material for the production of alkyl esters having Cs to C12 alkyl chain useful in biolubricants from a feedstock including one or more fatty acid glycerol esters and one or more fatty acids is also disclosed. The catalyst composite material includes fly ash. In accordance with an aspect the catalyst composite material includes at least 1 weight percentage of fly ash. In accordance with an aspect the catalyst composite material includes 30 weight percentage of fly ash.
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Specific embodiments are described below:
A process for production of alkyl esters comprises reacting a feedstock that includes one or more fatty acid glycerol esters or one or more fatty acids or mixture thereof with a C5 to C12 alcohol in the presence of fly ash as a catalyst.
Such process(s), wherein the reaction is carried out at a temperature between 120 °C and 250 °C under autogeneous pressure for a period of 30 minutes to 8 hours.
Such process(s), wherein the fly ash functions as a catalyst in the transesterification of the fatty acid glycerol esters and the esterification of fatty acids.
Such process(s), wherein the amount of fly ash used as a catalyst is in the range of 1 to 30 weight percentage with respect to the feedstock.
Such process(s), wherein the fly ash comprises of two or more of SiO2, AI2O3, Fe2O3. CaO, MgO and SO3.
Such process(s), wherein the fly ash comprises of 5 to 12 weight percentage SiO2, 2 to 11 weight percentage AI2O3, 0.50 to 2.0 weight percentage Fe2O3, 35 to 60 weight percentage CaO, 0.40 to 1 weight percentage MgO and 26 to 30 weight percentage SO3.
Such process(s), wherein the process further comprises of recovering the fly ash from the reaction mixture.
Such process(s), wherein the recovered fly ash is recycled.
Such process(s), wherein the process further comprises of separating the fly ash from the reaction mixture, washing and drying the washed fly ash and reusing the fly ash as a catalyst for producing alkyl esters.
Such process(s), wherein the fatty acid ester is a mono-, di- or tri-ester of glycerol with varied degree of unsaturation in the fatty acid chain.
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Such process(s), wherein the alcohol is any of pentanol, hexanol, heptanol, 2-ethylhexanol, octanol, decanol, undecanol, dodecanol or their mixtures.
Such process(s), wherein the molar ratio of the feedstock to alcohol can be in the range of 3 to 60 preferably in the range of 6 to 30 and most preferably in the range of 7.5 to 15.
Alkyl esters obtained by such process(s).
Further Specific embodiments are described below:
A catalyst composite material for the production of alkyl esters having a C5 to C12 alkyl chain from a feedstock including one or more fatty acid glycerol esters or one or more fatty acids or mixture thereof, wherein the catalyst includes fly ash.
Such catalyst composite material(s), wherein the amount of fly ash in the catalyst composite material is at least 30 weight percentage and the remaining may be any inert or active component.
Such catalyst composite material(s), wherein the fly ash comprises of 5 to 12 weight percentage SiO, 22 to 11 weight percentage A1203, 0.50 to 2.0 weight percentage Fe2O3, 35 to 60 weight percentage CaO, 0.40 to 1 weight percentage MgO, and 26 to 30 weight percentage S03.
Such catalyst composite material(s) wherein the fly ash comprises of two or more of SiO2. A12O3, Fe2O3, CaO, MgO and SO3.
The following examples are provided to explain and illustrate certain preferred embodiments of the process of the invention.
100 g of soybean oil, 225 g of 2-ethylhexanol and 10 g of fly ash were put in a batch reactor maintained at 220°C for 6 hours under autogenous pressure. Product mixture was collected and catalyst was filtered off. Two layer of liquid were present, upper one contained
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alkyl esters (biolubricant) and glycerol is present as lower layer. Two layers of liquid were separated using separating funnel.
INDUSTRIAL APPLICABILITY
The process as described produces alkyl esters used as biolubricants in an economically efficient and an environmental friendly manner. As fly ash is a solid catalyst, it can be easily separated from the reaction mixture and re-used thereby eliminating the need of neutralization step and aqueous washes that are associated with use of conventional catalysts. Moreover, as fly ash catalyses both the esterification reaction of the free fatty acids and the transesterification of triglycerides that are present in the fatty acid starting material (free fatty acids and, oils and fats). The process has several advantages. Firstly, the efficiency of the process increases since no acid pre-treatment process and subsequent neutralization steps are needed. Also, alkyl ester (biolubricant) along with glycerine is generated as the only reaction product without any contaminations. This enables easy separation of the two immiscible layers from the catalyst, yielding alkyl esters in quantitative yield that needs no further purification. The contaminations can only come from such sources where the free acid contents are higher than 20 weight percentage in the oil, as seen in the case of acid oil. Fly ash separated from the reaction mixture does not lose its catalytic activity and may be reused as a catalyst, thereby reducing the cost of biolubricant production. Moreover, the use of fly ash provides an alternate to the disposal related concerns of fly ash generated in industries. The presence of calcium oxide in fly ash plays a significant role in the transesterification and the esterification reaction.
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We Claim:
1. A process for production of alkyl esters comprises reacting a feedstock that includes one or more fatty acid glycerol esters or one or more fatty acids or mixture thereof with a C5 to C12 alcohol in the presence of fly ash as a catalyst.
2. A process as claimed in claim 1, wherein the reaction is carried out at a temperature between 120 °C and 250 °C under autogeneous pressure for a period of 30 minutes to 8 hours.
3. A process as claimed in claim 1, wherein the fly ash functions as a catalyst in the transesterification of the fatty acid glycerol esters and the esterification of fatty acids.
4. A process as claimed in claim 1, wherein the amount of fly ash used as a catalyst is in the range of 1 to 30 weight percentage with respect to the feedstock.
5. A process as claimed in claim 1, wherein the fly ash comprises of two or more of SiO2, A12O3. Fe2O3, CaO, MgO and SO3.
6. A process as claimed in claim 1 or 5, wherein the fly ash comprises of 5 to 12 weight percentage SiO2.2 to 11 weight percentage AI2O3, 0.50 to 2.0 weight percentage Fe2O3, 35 to 60 weight percentage CaO, 0.40 to 1 weight percentage MgO and 26 to 30 weight percentage SO3.
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7. A process as claimed in claim 1, wherein the process further comprises of recovering the fly ash from the reaction mixture.
8. A process as claimed in claim 7, wherein the recovered fly ash is recycled.
9. A process as claimed in claim 7 or 8, wherein the process further comprises of separating the fly ash from the reaction mixture; washing and drying the washed fly ash and reusing the fly ash as a catalyst for producing.alkyl esters.
10. A process as claimed in claim 1, wherein the fatty acid ester is a mono-, di- or tri-ester of glycerol with varied degree of unsaturation in the fatty acid chain.
11. A process as claimed in claim 1, wherein the alcohol is any of pentanol, hexanol, heptanol, 2-ethylhexanol, octanol, decanol, undecanol, dodecanol or their mixtures.
12. A process as claimed in claim 1, wherein the molar ratio of the feedstock to alcohol can be in the range of 3 to 60 preferably in the range of 6 to 30 and most preferably in the range of 7.5 to 15.
13. Alkyl esters obtained by a process as claimed in any preceding claim.
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14. A catalyst composite material for the production of alkyl esters having a C5 to C12 alkyl chain from a feedstock including one or more fatty acid glycerol esters or one or more fatty acids or mixture thereof, wherein the catalyst includes fly ash.
15. A catalyst composite material as claimed in claim 14, wherein the amount of fly ash in the catalyst composite material is at least 30 weight percentage and the remaining may be any inert or active component.
16. A catalyst composite material as claimed in claim 14, wherein the fly ash comprises of 5 to 12 weight percentage SiO, 22 to 11 weight percentage A1203, 0.50 to 2.0 weight percentage Fe2O3, 35 to 60 weight percentage CaO, 0.40 to 1 weight percentage MgO. and 26 to 30 weight percentage SO3.
17. A catalyst composite material as claimed in claim 14 wherein the fly ash comprises of two or more of SiO2. A12O3, Fe2O3, CaO, MgO and SO3.
18. A process for producing alkyl esters substantially as herein described.
19. A catalyst composite material for the production of alkyl esters having a C5 to C12 alkyl chain substantially as herein described.
Dated this 17th day of 2009
Essenese Obhan
of Obhan & Associates
Agent of the Applicants
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