One-pot process for the production of biodiesel and glycerol ether mixtures useful as biofuels

Abstract

A process for the conversion of a feedstock containing one or more fatty acid triglycerides to a mixture containing one or more fatty acid alkyl esters and t-alkyl glycerols, including reacting the feedstock with a compound of formula (I):
ROR.sup.I(I) wherein: R.sup.I is an alkyl, alkenyl or alkynyl having 1-18 carbon atoms; R is H or a tertiary alkyl group, wherein the reaction takes place in the presence of an acid transesterification catalyst by irradiation with microwaves and/or ultrasound and/or radio waves.

Claims

1. A process for converting a feedstock containing one or more triglycerides of fatty acids to a mixture containing one or more alkyl esters of fatty acids and t-alkyl glycerols, comprising carrying out a reaction of said feedstock with a compound of formula (I):
ROR.sup.I (I) wherein: R.sup.I is an alkyl, alkenyl or alkynyl having 1-18 carbon atoms; R is H or a tertiary alkyl group of formula (II): ##STR00002## wherein R.sup.III, R.sup.IV and R.sup.V are independently a straight or branched alkyl, alkenyl or alkynyl group having 1 to 6 carbon atoms; wherein said reaction is carried out in the presence of an acid transesterification catalyst by irradiation with microwaves and/or ultrasound and/or radio waves, said reaction produces a mixture containing one or more alkyl esters of fatty acids and t-alkyl glycerols, provided that when R is H in the compound of formula (I), an alcohol of formula ROH is added, wherein R is the tertiary alkyl group of formula (II) as defined above, in an equimolar amount to R.sup.IOH.

2. The process according to claim 1, wherein R.sup.III, R.sup.IV and R.sup.V in formula (II) are selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, t-butyl, ethenyl, propenyl, isopropenyl, butenyl, isobutenyl, hexenyl, ethynyl, propynyl and butynyl.

3. The process according to claim 2, wherein R.sup.III, R.sup.IV and R.sup.V in formula (II) are methyl.

4. The process according to claim 2, wherein R.sup.I in formula (I) is selected from the group consisting of methyl, ethyl, propyl, isopropyl and butyl.

5. The process according to claim 3, wherein R.sup.I in formula (I) is selected from the group consisting of methyl, ethyl, propyl, isopropyl and butyl.

6. The process according to claim 1, wherein R.sup.I in formula (I) is selected from the group consisting of methyl, ethyl, propyl, isopropyl and butyl.

7. The process according to claim 6, wherein R.sup.I in formula (I) is methyl.

8. The process according to claim 1, wherein the compound of formula (I) is tert-butyl methyl ether.

9. The process according to claim 1, wherein the feedstock is selected from the group consisting of: vegetable oils selected from the group consisting of coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil, canola oil, safflower oil, sesame oil, soybean oil, sunflower oil, almond oil, beech nut oil, cashew oil, hazelnut oil, macadamia oil, pine nut oil, pistachio oil, walnut oil, citrus oils, grapefruit seed oil, lemon oil, orange oil, castor oil, hemp oil, mustard oil, radish oil, rice bran oil, salicornia oil, soybean oil, jatropha oil, jojoba oil, linseed oil, poppy oil, stillingia oil, fruit tree oil, artichoke oil, carrot seed oil, mango oil and sea-buckthorn oil; animal fats selected from the group consisting of beef tallow, lard, poultry fat and fish oils; waste oils and fats from an industry selected from the group consisting of restaurants, catering, agrifood, and seafood.

10. The method according to claim 1, wherein irradiation takes place with only one type of electromagnetic frequency selected from the group consisting of microwaves, ultrasound and radio waves or with different types of said electromagnetic frequency, simultaneously or in succession.

11. The method according to claim 1, wherein the acid catalyst used in the reaction may be a free acid catalyst or immobilised on a support.

12. The process according to claim 11, wherein the acid catalyst is selected from the group consisting of: strong mineral acids and organic acids; zeolites, molecular sieves, phosphates, zirconates, kaolinite, montmorillonite, pillared clays, hydrotalcites and acid ion-exchange resins; solid acid or acid-functionalised materials selected from the group consisting of perfluorinated oxides, polymers and combinations thereof; silicas and silicas doped with Al, Ti or Zr in different morphologies, heteropolyacids, acids adsorbed and/or covalently bonded to metal oxides; organic sulphonic and/or organic carboxylic acids immobilised on amorphous silica and/or meso- and microstructured silica; polyoxymetalates stabilised on silica and/or titania; Keggin structures containing niobium ions; niobium oxides; and ionic liquids and/or carbon nanotubes functionalised with organic sulphonic acids and/or organic carboxylic acids.

13. The process according to claim 12, wherein the acid catalyst is alkylsulphonic acid bound to amorphous silica.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: HPLC analysis of the reaction mixture of Example 1

(2) FIG. 2: HPLC analysis of the reaction mixture of Example 2

(3) FIG. 3: Schematic illustration of a reaction

EXAMPLES

Example 1

(4) Conversion of Tripalmitin to a Mixture of Methyl Palmitate and Glycerol Tert-Butyl Ethers

(5) 500 mg of glycerol tripalmitate (MW 807.32, 0.619 mmol), dissolved in 1.6 ml of tert-butyl-methyl ether (d 0.744 mg/ml, MW 88.15, 24.5 mmol), is placed in a microwave test tube, and 30 mg of catalyst, consisting of amorphous silica 10% functionalised with sulphonic groups, is added to the solution. The reaction mixture is irradiated by 20 watt microwaves, under stirring, for a reaction time of up to 3 hours. The HPLC assay demonstrates the almost total conversion of glycerol tripalmitate to methyl palmitate and a mixture of mono- and di-tert-butyl glycerol ethers, in a 70:30 ratio. There is no formation of free glycerol, as shown in FIG. 1.

Example 2

Conversion of Soybean Oil to a Mixture of FAMEs and Glycerol Tert-Butyl Ethers

(6) 1 g of soybean oil (d 0.917 mg/ml, 0.619 mmol), dissolved in 3.2 ml of tert-butyl-methyl ether (d 0.744 mg/ml, MW 88.15, 24.5 mmol), is placed in a microwave vial, and 30 mg of catalyst, consisting of amorphous silica 10% functionalised with sulphonic groups, is added to the solution. The reaction mixture is irradiated by 20 watt microwaves, under stirring, for a reaction time of up to 3 hours. The HPLC assay demonstrates the almost total conversion of soybean oil to a mixture of fatty acid methyl esters, FAME, mono- and di-tert-butyl glycerol ethers, the latter in a 70:30 ratio. There is no formation of free glycerol, as shown in FIG. 2.