Designer Biosynthetic Jet Fuels Derived from Isoprene and α-Olefins

Abstract

Isoprene was hydrovinylated with a series of α-olefins (1-pentene, 1-hexene, 1-heptene, 1-octene) to produce acyclic branched C 10 −C 13 alkenes. The process utilized CoBr 2 (DPPE) as the precatalyst in loadings as low as 0.1 mol % and zinc as the reducing agent. Use of the cobalt catalyst resulted in primarily 1,4-addition, with carbon coupling at the 4-position of isoprene. A significant amount (∼20%) of the coupling products at the 1-position of isoprene was also observed. Each of the discrete C 10 , C 11 , C 12 , and C 13 products were then hydrogenated with 10% Pd/C (200 °C; 650 psi H 2 ) to yield jet fuel blendstocks. In addition to the reactions with pure α-olefins, an equimolar mixture of the C 5 −C 8 α-olefins was used to mimic a stream of olefins produced from ethanol dehydration/oligomerization or Fischer−Tropsch catalysis. The different fuel blends exhibited densities ranging from 0.73 to 0.76 g mL −1 , gravimetric net heats of combustion (NHOC) from 43.91 to 44.13 MJ kg −1 , and −20 °C kinematic viscosities from 2.4 to 6.3 mm 2 s −1 . The NHOC values were ∼2.9% higher than the lower limit for Jet-A, while the low-temperature viscosities were up to 70% lower than the upper limit for Jet-A. In addition to studying the suitability of the lightly branched hydrocarbons generated in this process as jet fuel blendstocks, it was of interest to explore their potential as diesel fuels. The equimolar C 10 −C 13 fuel mixture exhibited a derived cetane number (DCN) of 56, which is 16 units higher than that required for Diesel #2 (40). The outstanding fuel properties of the isoprene-derived fuels suggest that they have applications as replacements for both petroleum-derived Jet-A and Diesel #2.

Integration of genome-scale metabolic model with biorefinery process model reveals market-competitive carbon-negative sustainable aviation fuel utilizing microbial cell mass lipids and biogenic CO2

“…These biofuel molecules, including: limonene, 1,8cineole, linalool, farnesene, bisabolene, and epi-isozizaene, can be converted into saturated forms (alkanes) through hydrogenation or oligomerization/hydrogenation processes ensuring optimal performance when blended into jet fuel (Li et al 2023;Baral et al 2019). In addition to terpenoids, isoprenol, a platform chemical (Keller et al 2023), can be catalytically upgraded into 1,4-dimethylcyclooctane (DMCO), which has a volumetric heat of combustion about 9.2% higher than petroleum Jet-A (Rosenkoetter et al 2019), potentially leading to substantial fuel savings or extended aircraft range upon commercial implementation (Baral et al 2019).…”

Isoprene Telomers for Biodiesel Applications

“…Herein, we explore a complementary strategy involving the telomerization of isoprene and alcohols for the generation of branched asymmetric ethers. Isoprene is a naturally occurring hemiterpene produced by many plants. , Recently, isoprene has also been produced in excellent yields using engineered enzymes. , The alcohols, on the other hand, are widely available chemicals in the biomass supply chain . In order to combine these two valuable feedstocks, the telomerization reaction was previously employed, which facilitates the dimerization of dienes in the presence of nucleophiles .…”

“…33,34 The alcohols, on the other hand, are widely available chemicals in the biomass supply chain. 35 In order to combine these two valuable feedstocks, the telomerization reaction was previously employed, which facilitates the dimerization of dienes in the presence of nucleophiles. 36 This approach not only allows rapid and easy upgradation of platform chemicals to higher molecular weight ethers but also operates at extremely low catalyst loadings.…”