High productivity Kolbe reaction process for transformation of fatty acids derived from plant oil and animal fat
Oils from plants and animal fats are hydrolyzed to fatty acids for a Kolbe reaction. The invention relates to a high productivity Kolbe reaction process for electrochemically decarboxylating C4-C28 fatty acids using small amounts of acetic acid to lower anodic passivation voltage and synthesizing C6-C54 hydrocarbons. The C6-C54 undergo olefin metathesis and/or hydroisomerization reaction process to synthesize heavy fuel oil, diesel fuel, kerosene fuel, lubricant base oil, and linear alpha olefin products useful as precursors for polymers, detergents, and other fine chemicals.
1. A method of increasing productivity of a Kolbe electrolysis reaction forming one or more C6to C54 hydrocarbons, the method comprising:
combining one or more C4-C28 fatty acids with a solvent and with an amount of acetic acid to create a reaction mixture,
wherein the one or more C4-C28 fatty acids is between about 80 weight percent to about 99.8 weight percent of a total carboxylic acid weight percent in the solvent, and
wherein the amount of the acetic acid is between about 0.2 weight percent to about 20 weight percent of the total carboxylic acid weight percent in the solvent; and
performing a Kolbe electrolysis reaction on the reaction mixture to produce the one or more C6to C54 hydrocarbons,
wherein the acetic acid in the reaction mixture lowers a passivation voltage of an electrode used in the Kolbe electrolysis reaction.
2. The method of claim 1 , wherein the solvent is a C1to C4 alcohol, methanol, ethanol, propanol, isopropanol, butanol, water, or a mixture thereof, and wherein the solvent is a mixture which contains between about 0.5 percent to about 50 percent water by volume.
3. The method of claim 1 , wherein the reaction mixture for the Kolbe electrolysis reaction is not a solution at room temperature.
4. The method of claim 1 , wherein the one or more C4-C28 fatty acids in the solvent are reacted with a base to form an amount of a salt of the one or more C4-C28 fatty acids.
5. The method of claim 1 , wherein an electrolyte is added to the reaction mixture to improve electrical conductivity of the Kolbe electrolysis reaction, and wherein the electrolyte is selected from the group consisting of a perchlorate salt, a p-toluenesulfonate salt, a tetrafluoroborate salt, and mixtures thereof
6. The method of claim 1 , wherein the Kolbe electrolysis reaction is conducted at a temperature in a range of about 15 ° C. to about 100 ° C.
7. The method of claim 1 , wherein a pressure is imposed on the reaction mixture during the Kolbe electrolysis reaction to change a rate of loss of the solvent, or of the acetic acid, or of a C1-C6 volatile fatty acid.
8. The method of claim 1 , wherein an electrical current supplied to electrodes is 0.05-1.0 amperes per cm 2 area of the electrodes.
9. The method of claim 1 , wherein a reacting surface of an anode electrode is a platinum group metal selected from the group consisting of a platinum, a iridium, a palladium, a ruthenium, a rhodium, an osmium, and a combination thereof; or is a carbon material selected from the group consisting of a graphite, a glassy carbon, a baked carbon, and a combination thereof or is a mixture of one or more of the metals of the platinum group metals and the one or more of the carbon materials.
10. The method of claim 1 , further comprising:
following the Kolbe electrolysis reaction with an olefin metathesis reaction using a C2-C5 aliphatic alkene or a mixture of C2-C5 aliphatic alkenes, wherein the olefin metathesis reaction modifies a chain length of the hydrocarbon.
11. The method of claim 1 , further comprising:
following the Kolbe electrolysis reaction with an ethenolysis reaction using ethene to obtain 1-decene, 1-heptene, 1-butene, 1-octene, 1-hexene, or 1,4-pentadiene.
12. The method of claim 11 , further comprising:
separating the products of the ethenolysis reaction to obtain 1-decene, 1-heptene, 1-butene, 1-octene, 1-hexene, 1,4-pentadiene, a diesel fuel, and a heavy fuel oil.
13. The method of claim 1 , further comprising:
hydroisomerizing at least some of the products from the Kolbe electrolysis reaction to produce a lubricant base oil.
14. The method of claim 13 , wherein the hydroisomerization reaction uses a catalyst which is a silica/alumina-based zeolite containing impregnated platinum, a reaction temperature between about 250 ° C. to about 400 ° C., a reaction pressure between about 10 bar to about 400 bar, and a hydrogen gas to a hydrocarbon ratio of about 2 to about 50.
15. The method of claim 1 , wherein a reaction mixture has an amount of a hydrolysis solvent and a hydrolysis base from a preceding hydrolysis reaction of a feedstock triglyceride.
16. The method of claim 1 , wherein the one or more C4 -C28 fatty acids in the Kolbe electrolysis reaction is at a concentration of between about 0.01 molar to about 1 molar.
17. The method of claim 1 , wherein the solvent is methanol.
18. The method of claim 1 , wherein the solvent is ethanol.
19. The method of claim 1 , wherein the solvent is a mixture of methanol and ethanol.
20. The method of claim 1 , wherein the weight percent of acetic acid is between 0.2 weight percent to about 5 weight percent.