Production of biodiesel from triglycerides via a thermal route

• US 20070137097A1
• Filed: 12/16/2005
• Published: 06/21/2007
• Est. Priority Date: 12/16/2005
• Status: Abandoned Application

• Current Assignee: Her Majesty The Queen In Right Of Canada As Represented By The Minister Or Natural Resources
• Original Assignee: Her Majesty The Queen In Right Of Canada As Represented By The Minister Or Natural Resources
• Inventors: Ikura, Michio
• Application Number:
  US11/304,658
• Publication Number:
  US 20070137097A1
• Time in Patent Office: Days
• US Class Current: 44/308
• CPC Class Codes: C10G 2300/1014 of vegetal origin
• CPC Class Codes: C10G 2300/1018 of animal origin
• CPC Class Codes: C10G 2300/807 Steam
• CPC Class Codes: C10G 3/40 Thermal non-catalytic treatment
• CPC Class Codes: C10L 1/026 for compression ignition
• CPC Class Codes: C11C 3/00 Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom sulfonated fats or oils C07C309/62; factice C08H; drying oils C09F
• CPC Class Codes: C11C 3/003 by esterification of fatty acids with alcohols C11C3/02 takes precedence
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02P 30/20 using bio-feedstock

Abstract

A method is presented for producing biodiesel from a triglyceride feedstock. The feedstock is first thermally cracked to remove contaminants and convert triglycerides to form a middle distillate fraction rich in fatty acids. The middle distillate fraction is then esterified the in the presence of an alcohol and a catalyst to produce a biodiesel stream. The biodiesel stream can be treated with a basic solution to convert unesterified free fatty acids to non-foaming metallic soaps, which can be removed by centrifugation, filtering or a combination thereof. A method is also provided for producing a biodiesel/naphtha mixture, in which a triglyceride feedstock is thermally cracked to produce a middle distillate fraction, a naphtha stream and a gas stream. The naphtha stream and the middle distillate fraction are then esterified to produce a mixed biodiesel/naphtha stream, which can be treated with a basic solution to convert unesterified free fatty acids to non-foaming metallic soaps. The basic salts are removed by known means.

Claims

1. A method of producing biodiesel from a triglyceride feedstock, the method comprising:

a. pretreating the triglyceride feedstock by thermal cracking to remove contaminants and convert triglycerides to form a middle distillate fraction rich in free fatty acids;

b. esterifying the middle distillate fraction in the presence of an alcohol and a catalyst to produce a biodiesel stream;

c. treating the biodiesel stream with a basic solution to convert unesterified free fatty acids to non-foaming metallic soaps; and

d. removing the non-foaming metallic soaps by centrifugation, filtering or a combination thereof.

2. The method of claim 1 wherein the basic solution is an aqueous solution of a compound selected from the group consisting of lithium hydroxide (LiOH), potassium hydroxide (KOH), magnesium hydroxide (Mg(OH)₂), and calcium hydroxide (Ca(OH)₂).

3. The method of claim 2 wherein the basic solution is an aqueous solution of calcium hydroxide or lithium hydroxide.

4. The method of claim 1 wherein the triglyceride feedstock is selected from the group consisting of restaurant trap grease, rendered animal fats, waste greases, low-quality vegetable oils and combinations thereof.

5. The method of claim 1 wherein thermal cracking is conducted at a temperature of from 390°

C. to 460°

C.

6. The method of claim 1 wherein thermal cracking is conducted at a temperature of from 410°

C. to 430°

C.

7. The method of claim 1 wherein the middle distillate fraction is esterified in the presence of methanol as the alcohol.

8. The method of claim 7 wherein esterifying is conducted at a temperature of from 70°

C. to 120°

C.

9. The method of claim 8 wherein esterifying is conducted at a temperature of from 85°

C. to 110°

C.

10. The method of claim 1, wherein the middle distillate fraction is esterified in the presence of an acid catalyst.

11. The method of claim 10 wherein the acid catalyst is selected from the group consisting of sulphuric acid (H₂SO_4(l)), sulphamic acid (H₂NSO₃H_(l)), formic acid (HCO₂H_(l)), acetic acid (CH₃CO₂H_(l)), propionic acid (CH₃CH₂CO₂H_(l)), hydrochloric acid (HCl_(l)), phosphoric acid (H₃PO_4(l)), sulphated metal oxides such as sulphated zirconia, and styrene divinylbenzne copolymers having SO₃H functional groups.

12. The method of claim 11 wherein the acid catalyst is a styrene divinylbenzene copolymer having an SO₃H functional group.

13. The method of claim 1, further comprising filtering the triglyceride feedstock before thermal cracking to remove macroscopic contaminant particles.

14. A method of producing a biodiesel/naphtha mixture from a triglyceride feedstock, the method comprising:

a. pretreating the triglyceride feedstock by thermal cracking to remove contaminants and convert triglycerides to produce a middle distillate fraction rich in free fatty acids, a naphtha stream and a gas stream;

b. esterifying the naphtha stream and middle distillate fraction in the presence of an alcohol and a catalyst to produce a mixed biodiesel/naphtha stream;

c. treating the mixed biodiesel/naphtha stream with a basic solution to convert unesterified free fatty acids to non-foaming metallic soaps; and

d. removing the non-foaming metallic soaps by centrifugation, filtering or a combination thereof.