ENERGY EFFICIENT BIODIESEL PRODUCTION FROM NATURAL OR INDUSTRIAL WASTE OIL

Abstract

A method of producing fatty acid alkyl ester from an organic oil source containing at least one free fatty acid, wherein the vegetable and/or animal waste oil has an acid number of at least 30 mg KOH/g and wherein the method comprises the steps of a) reacting the oil source with glycerol at a temperature, which is at least 110° C. and does not exceed 180° C. during the reaction, in the presence of a catalyst comprising at least methane sulfonic acid or the homo anhydride thereof; and b) acidic transesterification at a temperature, which is at least 110° C. and does not exceed 160° C. during the reaction of the reaction product from step a) with an alkanol; and c) isolating the fatty acid alkyl ester from the reaction product of step b).

Claims

1. A method of producing fatty acid alkyl ester from an organic oil source comprising at least one free fatty acid, wherein the organic oil source has an acid number of at least 30 mg KOH/g and wherein the method comprises the steps of a) reacting the oil source with glycerol at a temperature, which is at least 110° C. and does not exceed 180° C. during the reaction, in the presence of a catalyst comprising at least methane sulfonic acid or the homo anhydride thereof; b) acidic transesterification at a temperature, which is at least 110° C. and does not exceed 160° C. during the reaction of the reaction product from step a) with an alkanol; and c) isolating the fatty acid alkyl ester from the reaction product of step b).

2. The method of claim 1, wherein the fatty acid alkyl ester is fatty acid methyl ester.

3. The method of claim 1, wherein the organic oil source is from used vegetable and/or animal oil and/or fat, by-products of the chemical and physical refining of vegetable and/or animal oil and/or fat, by-products of the refining of glycerol from biodiesel, fatty acids from distillation and non-distillation, trap grease, hydrolytically cleaved fatty substances, distilled and non-distilled fatty acids resulting from the cleaving of soap, or mixtures thereof.

4. The method of claim 1, wherein the organic oil source has an acid number of at least 40 mg KOH/g oil source.

5. The method of claim 1, wherein in step a) the temperature does not exceed 170° C.

6. The method of claim 1, wherein in step a) the temperature is at least 120° C.

7. The method of claim 1, wherein in step b) the temperature does not exceed 160° C.

8. (canceled)

9. The method of claim 1, wherein in step b) the temperature is at least 115° C.

10. The method of claim 1, wherein in step a) the initial molar ratio of glycerol to free fatty acid calculated on the basis of the acid number of the oil is from 1:2 to 1.2:1.

11. The method of claim 1, wherein in step a), step b) or step a) and b) the amount of the methane sulfonic acid or anhydride thereof is from 0.5 to 1.5 weight-% based on the total amount of the oil source.

12. The method of claim 1, wherein in step c) the isolation comprises a neutralization step.

13. The method of claim 1, wherein in step c) the isolation comprises a distillation step.

14. The method of claim 13, wherein the distillation in step c) is carried out under reduced pressure.

15. The method of claim 1, wherein between step a) and step b) no phase separation is carried out.

16. The method of claim 1, wherein step a) and step b) are carried out in the same reactor vessel.

17. The method of claim 1, wherein after step b) and before step c) a step b′) of removing at least partly the alkanol by using the reaction temperature, is introduced.

18. The method of claim 17, wherein step b′) comprises lowering pressure of the reaction.

19. The method of claim 17, wherein step b′) comprises lowering atmospheric pressure of the reaction.

Description

EXAMPLES

Analytical Details

[0062] Waste oil characterization: [0063] Appearance: black liquor containing dark brown sludge sediment [0064] Viscosity (Brookfield, rt): 36.8 mPa*s (60 rpm/Spindel1/23° C.) [0065] Iodine number: 101.8 gl.sub.2/100g [0066] Acid number: 140 mgKOH/g

A) 1. Step: Filtration

[0067] Waste oil was filtered two times at rt via paper filter (1.6-2 .Math.m). Residue: appr. <1 wt% Water content after filtration: 0.5%

[0068] 2. Step: Acidic degumming and esterification 500 g filtered waste oil, 5 g water, 105 g Glycerol and 4 g Lutropur MSA (methane sulfonic acid, 70% active content) were mixed in a reaction vessel and heated up to 140° C. under vacuum which was kept constant at 10 kPa. Reaction time was 4 h.

Analytical Result

[0069] Table 1: Time dependency of Acid number in mgKOH/g The esterification of free fatty acid with glycerol was controlled by taking out samples (approx. 4 g). The sample is washed with ca. 4 g glycerol to eliminate MSA from the mixture. Glycerol and oil phase are separated. From the oil phase the acid number is measured according to DIN EN 14104.

TABLE-US-00001 0 h 0.5 h 1.0 h 2.0 h 3.0 h 4.0 h Example 1 102 41 20 17 15 14

[0070] After reaction 552 g reaction product was obtained from step 2 and 28 g distillate (mainly water).

[0071] Process a) was done two times to get enough raw material for b).

B) 3. Step

[0072] Acidic transesterification 745 g reaction product from a) and 223 g methanol (30 wt% related to oil) was filled in a pressure reactor and heated up to 120° C. and stirred. Reaction pressure was 3 \* 10.sup.5 Pa. Reaction time was 3 h. After 3 h reactor was cooled down.

Analytical Results

[0073] 806 g reaction product was obtained (missing product weight is due to control of acid number during the reaction - 4 times) Acid number (determined as described in Tab. 1) after 3 h was 10 mgKOH/g.

C) 4. Step

[0074] Product resulting from b) was shift to a distillation column and heated to 130° C. under stirring at atmospheric pressure. 23 g methanol was distilled.

[0075] 5. Step 772 g reaction product was neutralized with 6.9 g NaOH (40% concentration) and phase separated in a separating funnel which is difficult as there is no visual difference in the phase (all black). Separation finish was judged by change of viscosity.

Analytical Results

[0076] Lower phase (glycerol/MSA phase and residual methanol from step 2) was 144 g. Upper phase (fatty acid methyl ester) from step 2) was 623 g.

[0077] 6. Step Fatty acid methyl ester phase was centrifuged but only little residue was observed.

[0078] 7. Step Purification of the fatty acid methyl ester after centrifuge is done by distillation at approx. 3 hPa and temperature of approx. 210° C.

[0079] Sulfur content of fatty acid methyl ester from step 7:

[0080] Distilled fatty acid methyl esters (biodiesel): <10 ppm sulfur.