Renewable jet fuel blendstock from isobutanol
View Patent ↗The present invention in its various embodiments is directed to methods for preparing a renewable jet fuel blendstock, and blendstocks prepared by such methods, comprising fermenting a biomass-derived feedstock to form one or more C 2 -C 6 alcohols such as isobutanol, catalytically dehydrate and oligomerize the alcohols to form higher molecular weight olefins (e.g., C 8 -C 16 olefins), hydrogenating at least a portion of the higher molecular weight olefins to form a renewable jet fuel blendstock comprising C 12 and C 16 alkanes which meet or exceed the requirements of ASTM D7566-10a for hydroprocessed synthesized paraffinic kerosene (SPK).
1. A process for preparing renewable jet fuel blendstock comprising:
(a) dehydrating renewable isobutanol, thereby forming a dehydration product comprising isobutene;
(b) oligomerizing at least a portion of the dehydration product, thereby forming a product comprising one or more C 8 , one or more C 12 , and one or more C 16 unsaturated oligomers;
(c) separating at least a portion of said one or more C 8 unsaturated oligomers produced in step (b);
(d) combining the separated portion of step (cc) with the dehydration product of step (b) prior to said oligomerization step (b);
(e) hydrogenating at least a portion of the product of step (b) in the presence of hydrogen, thereby forming a renewable jet fuel blendstock comprising one or more C 12 and one or more C 16 saturated alkanes; and
(f) adjusting the ratio of C 12 and C 16 saturated alkanes provided by step (ge) to form a renewable jet fuel blendstock which meets or exceeds the requirements of ASTM D7566-10a for hydroprocessed synthesized paraffinic kerosene (SPK).
2. The process of claim 1 , wherein said dehydrating is carried out in the presence of a dehydration catalyst, said oligomerizing is carried out in the presence of an oligomerization catalyst, and said hydrogenating is carried out in the presence of a hydrogenation catalyst.
3. The process of claim 2 , wherein each of said dehydrating, oligomerizing, and hydrogenating are carried out in a different reaction zone.
4. The process of claim 1 , wherein said dehydrating and/or said oligomerizing are carried out in the presence of an acidic catalyst, wherein the acidic catalyst for dehydrating and the acidic catalyst for oligomerizing is the same or different.
5. The process of claim 4 , wherein said acidic catalyst for dehydrating and said acidic catalyst for oligomerizing are each independently selected from the group consisting of inorganic acids, organic sulfonic acids, heteropolyacids, perfluoroalkyl sulfonic acids, metal salts thereof, mixtures of metal salts, and combinations thereof.
6. The process of claim 5 , wherein said acid catalyst for oligomerizing is Amberlyst 35.
7. The process of claim 1 , wherein said hydrogenating is carried out in the presence of a hydrogenation catalyst selected from the group consisting of iridium, platinum, palladium, rhodium, nickel, ruthenium, rhenium and cobalt; compounds thereof; and combinations thereof.