Process for producing biodiesel fuel with reduced viscosity and a cloud point below thirty-two (32) degrees fahrenheit

• US 6,015,440 A
• Filed: 10/31/1997
• Issued: 01/18/2000
• Est. Priority Date: 10/31/1997
• Status: Expired due to Fees

• Current Assignee: Board of Regents of the University of Nebraska
• Original Assignee: Board of Regents of the University of Nebraska
• Inventors: Noureddini, Hossein
• Primary Examiner(s): MEDLEY, MARGARET B
• Application Number:
  US08/961,939
• Time in Patent Office: 809 Days
• Field of Search: 44/308, 44/443, 44/447, 44/448, 44/449, 44/386, 44/388, 44/389
• US Class Current: 44/388
• CPC Class Codes: C10L 1/026 for compression ignition
• 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

Abstract

Triglycerides are reacted in a liquid phase reaction with methanol and a homogeneous basic catalyst. The reaction yields a spatially separated two phase result with an upper located non-polar phase consisting principally of non-polar methyl esters and a lower located phase consisting principally of glycerol and residual methyl esters. The glycerol phase is passed through a strong cationic ion exchanger to remove anions, resulting in a neutral product which is flashed to remove methanol and which is reacted with isobutylene in the presence of a strong acid catalyst to produce glycerol ethers. The glycerol ethers are then added back to the upper located methyl ethyl ester phase to provide an improved biodiesel fuel.

Claims

1. A process of producing an oxygenated biodiesel fuel with a cloud-point below 32 degrees Fahrenheit, said oxygenated biodiesel fuel consisting of a mixture of transesterified triglycerides and a cloud-point reducing amount of etherified glycerol, said process comprising the steps of:

a. providing a quantity of triglycerides;

b. transesterifying at least a portion of said triglycerides by mixing with a base and methyl alcohol to produce a mixture of transesterified triglycerides and crude glycerol;

c. separating out, in an essentially pure state, most of said transesterified triglycerides from said mixture of transesterified triglycerides and crude glycerol, thereby also providing separated-out substantially crude glycerol;

a. etherifying the crude glycerol provided in step c., by mixing isobutylene therewith in sufficient quantity to maintain an isobutlyene;

glycerol mole ratio which favors production of higher glycerol di and tri-ethers as opposed to mono-ethers; and

e. remixing at least a portion of the resulting glycerol ethers produced in step d., with at least a portion of the step c. separated-out, essentially pure state transesterified triglycerides;

said steps a.-e. serving to produce said oxygenated biodiesel fuel with a cloud-point below 32 degrees Fahrenheit, without other cloud-point reducing additive(s) and/or glycerol ethers from a source other than that identified in step d., being added thereinto.

2. A process of producing an oxygenated biodiesel fuel with a cloud-point below 32 degrees Fahrenheit as in claim 1, which further comprises at least one additional step selected from the group consisting of:

f. after step d. and before step e., by treating said etherified glycerol with water, separating out unwanted double hydroxyl group containing ethers of glycerol produced in step d., prior to remixing at least a portion of the resulting glycerol ethers and at least a portion of said essentially pure state transesterified triglycerides separated-out in step c.; and

g. diverting a portion of the crude glycerol produced in the step b. transesterification of said triglycerides and which is substantially separated-out in step c., prior to performing the etherification of said crude glycerol in step d.

3. A process of producing an oxygenated biodiesel fuel with a cloud-point below 32 degrees Fahrenheit as in claim 1, in which the step of performing transesterification of at least a portion of said triglycerides to produce a mixture of transesterified triglycerides and crude glycerol involves providing and using a static-mixer-heat exchanger/reactor unit comprised of feed tube(s) which have an internal volume and outer surface and through which feed tube(s) said quantity of triglycerides and base and methyl alcohol is caused to flow in use, which heat exchange/reactor further includes means for causing steam or heating fluid to flow around the outer surface of said feed tube(s) in use so as to control the temperature of said triglycerides and base and methyl alcohol during passage through said feed tube(s).

8. A process of producing an oxygenated biodiesel fuel, with a cloud-point below 32 degrees Fahrenheit as in claim 1, which further comprises at least one additional step selected from the group consisting of:

a. passing the crude glycerol through a strong cationic ion exchanger to remove anions, resulting in substantially de-ionized crude glycerol; and

b. passing said transesterified triglycerides through a strong cationic ion exchanger to remove anions, resulting in substantially de-ionized transesterified triglycerides.

4. An oxygenated biodiesel fuel, with a cloud-point below 32 degrees Fahrenheit, consisting of a mixture of transesterified triglycerides and a cloud-point reducing amount of etherified glycerol, said oxygenated biodiesel fuel being produced by a process comprising the steps of:

a. providing a quantity of triglycerides;

b. esterifying at least a portion of said triglycerides by mixing with a base and methyl alcohol to produce a mixture of esterified triglycerides and crude glycerol;

c. separating-out, in an essentially pure state, most of said esterified triglycerides from said mixture of esterified triglycerides and crude glycerol, thereby also providing separated-out substantially crude glycerol;

d. etherifying the crude glycerol provided in step c., by mixing isobutylene therewith; and

e. remixing at least a portion of the resulting glycerol ethers produced in step d., with at least a portion of the step c. separated out, essentially pure state esterified triglycerides to provide said biodiesel fuel with a cloud-point below 32 degrees Fahrenheit;

said steps a.-e. serving to produce said oxygenated biodiesel fuel with a cloud-point below 32 degrees Fahrenheit without other cloud-point reducing additive(s) and/or etherified glycerol from a source other than that identified in step d., being added thereinto;

said process optionally further comprising at least one additional step selected from the group consisting of;

f. after step d, and before step e., by treating said etherified glycerol with water, separating out unwanted double hydroxyl group containing ethers of glycerol produced in step d., prior to remixing the resulting mixture of glycerol ethers with at least a portion of the essentially pure state esterified triglycerides separated out in step c.; and

g. diverting a portion of the crude glycerol produced in the step b. esterification of said triglycerides and which is provided in step c., prior to performing the etherification of the crude glycerol provided in step d.

5. An oxygenated biodiesel fuel, with a cloud-point below 32 degrees Fahrenheit, consisting of a mixture of transesterified triglycerides and a cloud-point reducing amount of etherified glycerol, said ethers of glycerol being produced from crude glycerol which is a by-product of a process which provides said esters of triglycerides, said esters of triglycerides being produced by transesterification of triglycerides provided from at least one source selected from the group consisting of:

plant and animal,

said oxygenated biodiesel fuel being produced by a procedure which comprises at least one step selected from the group consisting of;

a. the step of passing said crude glycerol through a strong cationic ion exchanger to remove anions, resulting in substantially de-ionized crude glycerol; and

b. the step of passing said transesterified triglycerides through a strong cationic ion exchanger to remove anions, resulting in substantially de-ionized transesterified triglycerides.

9. A process of producing an oxygenated biodiesel fuel, with a cloud-point below 32 degrees Fahrenheit as in claim 5, which comprises the step of passing the transesterified triglycerides through a strong cationic ion exchanger to remove anions, resulting in substantially de-ionized transesterified triglycerides.

6. An oxygenated biodiesel fuel, with a cloud-point below 32 degrees Fahrenheit, consisting of a mixture of transesterified triglycerides and a cloud-point reducing amount of etherified glycerol, said oxygenated biodiesel fuel being produced by a procedure comprising the steps of:

a. reacting triglycerides in a liquid phase with methanol and a homogeneous basic catalyst, such that said reaction yields a spatially separated two phase result with an upper located non-polar phase consisting principally of non-polar methyl esters and a lower located phase consisting principally of glycerol and residual methyl esters;

b. passing the glycerol through a strong cationic ion exchanger to remove anions, resulting in a substantially de-ionized glycerol;

c. flashing said substantially de-ionized glycerol produced in step b. to remove methanol;

d. reacting said flashed substantially de-ionized glycerol produced in step c. with isobutylene in the presence of a strong acid catalyst to produce glycerol ethers; and

e. adding at least a portion of said glycerol ethers produced in step d. to at least a portion of the non-polar methyl esters produced in step a. to provide said biodiesel fuel with a cloud-point below 32 degrees Fahrenheit;

said steps a.-e. serving to produce said oxygenated biodiesel fuel with a cloud-point below 32 degrees Fahrenheit without other cloud-point reducing additive(s) and/or etherified glycerol from a source other than that identified in step d. being added thereinto.

7. An oxygenated biodiesel fuel, with a cloud-point below 32 degrees Fahrenheit as in claim 6, said oxygenated biodiesel fuel being produced by a procedure which further comprises the step of passing said non-polar methyl esters produced in step a. through a strong cationic ion exchanger to remove anions, resulting in substantially de-ionized methyl esters prior to the step e. adding of at least a portion of said glycerol ethers produced in step d. to at least a portion of the non-polar methyl esters produced in step a., to provide said biodiesel fuel with a cloud-point below 32 degrees Fahrenheit;

said steps a.-e. and said additional step of passing said non-polar methyl esters produced in step a. through a strong cationic ion exchanger, serving to produce said oxygenated biodiesel fuel with a cloud-point below 32 desrees Fahrenheit without other cloud-point reducing additive(s) and/or etherified glycerol from a source other than that identified in d. being added thereinto.

10. A method of producing a biodiesel fuel with a cloud-point below 32 degrees Fahrenheit, said biodiesel fuel consisting of a mixture of esterified triglycerides and a cloud-point reducing amount of etherified glycerol, said method comprising the steps of:

a. providing triglycerides;

b. esterifying said triglycerides to provide a mixture of esterified triglycerides and crude glycerol;

c. substantially separating said esterified triglycerides from said crude glycerol;

d. etherifying said crude glycerol by treating with isobutylene; and

e. mixing together at least a portion of said esterified triglycerides and at least a portion of said etherified crude glycerol to provide said biodiesel fuel with a cloud-point below 32 degrees Fahrenheit;

said steps a.-e, serving to produce said biodiesel fuel with a cloud-point below 32 degrees Fahrenheit without the required addition of other cloud-point reducing additives and/or the required addition of etherified glycerol from a source other than that identified in step d.

11. A method of preparing a biodiesel fuel with a cloud-point below thirty-two (32) degrees, said biodiesel fuel consisting of a mixture of esterified triglycerides and a cloud-point reducing amount of etherified glycerol as in claim 10, which method further comprises at least one additional step selected from the group consisting of,

a. passing the crude glycerol through a strong cationic ion exchanger to remove anions, resulting in substantially de-ionized crude glycerol;

and

b. passing said esterified triglycerides through a strong cationic ion exchanger to remove anions, resulting in substantially de-ionized esterified triglycerides.

12. A method of preparing a biodiesel fuel with a cloud-point below thirty-two (32) degrees, said biodiesel fuel consisting of a mixture of esterified triglycerides and a cloud-point reducing amount of etherified glycerol as in claim 10, in which said method of producing said biodiesel fuel is a continuous process.