Process for conversion of waste to fuel
A method for conversion of food waste to biofuel can include a first fermentation in which food waste is converted C 2 -C 4 short-chain carboxylic acids, and a second fermentation in which the C 2 -C 4 short-chain carboxylic acid are elongated into C 5 -C 8 medium-chain carboxylic acids. Medium-chain carboxylic acids can undergo hydrogenation-dehydration of the medium-chain carboxylic acids into C 5 -C 8 linear olefins. The C 5 -C 8 linear olefins are then oligomerized to a C 10 -C 25 mixture comprising olefins, paraffin, cycloparaffins, and aromatics through dimerization; and saturated to C 10 -C 25 mixture by hydrogenation to produce the biofuel.
1. A method for conversion of food waste to biofuel, comprising:
a first fermentation in which food waste is converted to C 2 -C 4 short-chain carboxylic acids resulting in an aqueous phase comprising the C 2 -C 4 short-chain carboxylic acids;
a second fermentation in which in a fermentation broth comprising the aqueous phase, the C 2 -C 4 short-chain carboxylic acid are elongated into C 5 -C 8 medium-chain carboxylic acids;
hydrogenation-dehydration of the medium-chain carboxylic acids into a C 5 -C 8 linear olefins;
oligomerizing the C 5 -C 8 linear olefins to a C 10 -C 25 mixture comprising C 10 -C 25 olefins, C 10 -C 25 paraffins, C 10 -C 25 cycloparaffins, and C 10 -C 25 aromatics through dimerization; and
saturating the C 10 -C 25 mixture by hydrogenation to produce the biofuel.
2. The method of claim 1 , wherein the second fermentation is a continuous fermentation and the C 5 -C 8 medium chain carboxylic acids are separated from the fermentation broth in situ.
3. The method of claim 2 , wherein the C 5 -C 8 medium chain carboxylic acids are separated from the fermentation broth in situ by solvent extraction or electrochemical separations.
4. The method of claim 1 , wherein the C 5 -C 8 medium chain carboxylic acids are separated from the fermentation broth ex situ.
5. The method of claim 1 , wherein the biofuel comprises jet fuel.
6. The method of claim 1 , wherein the biofuel comprises diesel fuel.
7. The method of claim 1 , wherein the biofuel comprises both jet fuel and diesel fuel.
8. The method of claim 1 , wherein the yield of the first fermentation is 70-85% C 2 -C 4 short-chain carboxylic acid.
9. The method of claim 1 , wherein the catalyst for hydrogenation and dehydrogenation comprises Cu/Al 2 O 3 —SiO 2 or Cu/acidic support material.
10. The method of claim 1 , wherein hydrogen is produced during the first fermentation and the method comprises flowing the hydrogen for use in the catalytic hydrogenation-dehydration of the medium-chain carboxylic acids.
11. The method of claim 1 , wherein the catalytic oligomerization produces a mixture of olefins, paraffins, cycloparaffins, and aromatics.
12. The method of claim 11 , wherein the aromatics comprises about 22% of the mixture.
13. The method of claim 11 , wherein the mixture comprises C 1 -C 4 olefins, C 1 -C 4 paraffins, and/or C 1 -C 4 unsaturated hydrocarbons, the method further comprising removing C 1 -C 4 olefins, C 1 -C 4 paraffins, and/or C 1 -C 4 other unsaturated hydrocarbons and using the removed C 1 -C 4 olefins, C 1 -C 4 paraffins, and/or C 1 -C 4 other unsaturated hydrocarbons to combust to generate heat, steam or generate power.
14. The method of claim 1 , wherein the first and second fermentations are performed in first and second fermenters.
15. The method of claim 1 , wherein the first and second fermentations are performed in the same fermenter.
16. The method of claim 1 , comprising performing an electrochemical membrane extraction on the aqueous phase to concentration the C 2 -C 4 short-chain carboxylic acids in the aqueous phase.
17. The method of claim 1 , comprising maintain pH during the second fermentation in a range of 4-9.
18. The method of claim 17 , wherein maintaining the pH during the second fermentation comprises adding a pH adjusting chemical during the second fermentation.
19. The method of claim 18 , wherein the pH adjusting chemical is NaOH.
20. The method of claim 18 , further comprising performing an electrochemical membrane extraction on the fermentation broth of the second fermentation after separating the C 5 -C 8 medium chain carboxylic acids to further separate the pH adjusting chemical from the fermentation broth.