A Simple Process for the Dimerization and Cross-Coupling of Isoprene and Myrcene to High-Performance Jet and Diesel Blendstocks

Abstract

Three high-energy density fuels were generated in a one-pot reaction from the [4+4]-cyclodimerization and cross-coupling of isoprene and myrcene using a homogeneous iron pyridineimine (PDI) catalyst. The resulting mixture of C10, C15, and C20 regio- and chemoselectively synthesized cyclooctadienes was fractionally distilled to yield three fractions. The isolated cyclic hydrocarbons were then hydrogenated, and the fuel properties were evaluated as potential jet and diesel blendstocks. F-1 was composed primarily of 1,4-dimethylcyclooctane (DMCO) and small quantities of 2,6-dimethyloctane (DMO), the latter from the hydrogenation of unreacted myrcene. F-2 was composed of the cross-product of isoprene and myrcene (MPCO), while F-3 consisted of myrcene dimers (BMCO). F-1 and F-2 exhibited an ∼6% higher density, 2.0–2.4 and 8.5–10% higher gravimetric and volumetric net heats of combustion, respectively, than the lower limits of Jet-A. F-3 exhibited a 1.7% higher gravimetric heat of combustion than Diesel #2 and an outstanding derived cetane number (DCN) of 51. Blends of F-2 and F-3 up to 50% by volume with DMO and Diesel #2 were prepared, focusing on blends that met the −40 °C kinematic viscosity requirement (<12.0 mm2/s) for Jet-A or the required 40 °C kinematic viscosity of Diesel #2 (2.1–4.1 mm2/s). The eight-membered cyclic hydrocarbons described herein are highly attractive due to the efficient catalytic process employed in their synthesis and the ability to produce the substrates from sustainable feedstocks. These blendstocks are aromatic-free, zero-sulfur fuel additives that have the potential to deliver enhanced performance compared to Jet-A and Diesel #2 while reducing the carbon footprint of the transportation sector.

Light-driven (cross-)dimerization of terpenes as a route to renewable C15 – C30 crudes for fuel and lubricant oil applications

“…While HAPD and HMD crudes have too high viscosities to be used stand-alone as diesel, they could be mixed in blends to afford the required viscosities. 24,29 Yet, these blends could possibly be made entirely from non-fossil sources, using for example the C15 fraction produced in the crossdimerization of α-phellandrene and isoprene. Indeed, adjustments of HAPID viscosity would be required to a lesser extent, as its viscosity is closer to that of D2 diesel (6.45 mm 2 s -1 , at 40 °C).…”

“…21 Indeed, hydrogenated monoterpenes themselves have been reported to have jet fuel properties, 22,23 whilst their hydrogenated C20 dimers can be suitable for diesel-like or other high energy density fuels. [24][25][26][27][28][29] Such reported methods of dimerization of monoterpenes are acid or metal catalyzed thermal reactions. The two monoterpenes α-and β-pinene have also been used in self-photosensitized cycloaddition with biomass-derived cyclic enones, yielding spiro-compounds suitable as jet fuels.…”

Light-driven (cross-)dimerization of terpenes as a route to renewable C15–C30crudes for fuel and lubricant oil applications

“…21 Indeed, hydrogenated monoterpenes themselves have been reported to have jet fuel properties, 22,23 whilst their hydrogenated C 20 dimers can be suitable for diesel-like or other high energy density fuels. [24][25][26][27][28][29] Such reported methods of dimerization of monoterpenes are acid or metal catalyzed thermal reactions. The two monoterpenes α-and β-pinene have also been used in self-photosensitized cycloaddition with biomass-derived cyclic enones, yielding spiro-compounds suitable as jet fuels.…”

High-Energy-Density Liquid Spiro-Norbornanes from Methylenenorbornane

“…9−11 For example, JP-10 (exo-isomer of tetrahydrodicyclopentadiene) is the synthetic fuel that can give 13−14% more energy in comparison to distilled kerosene. 12−17 In recent years, various synthetic fuels have been developed, for instance, fully hydrogenated and isomerized tricyclopentadiene, 18,19 cyclopropanated terpenes, 20−22 alkyladamantanes, 23,24 hydrogenated dimers of norbornene and norbornadiene, 25,26 dimers of isoprene and myrcene, 27 etc.…”

“…The replacement of conventional jet fuels from petroleum refineries, such as kerosene, with synthetic ones has acquired particular relevance with the development of commercial, military, and space aviation because of their enhanced performance properties. − A synthetic jet fuel made from petrochemical or biohydrocarbon feedstocks has a significant advantage because it can be easily modified to suit current aircraft designs. Modern aircraft vehicles are often volume-limited, and the application of high-energy density fuels reduces fuel tank volumes, saving more space for useful components, or extending the maximum flight range without refueling. , In addition, liquid propellants used must also have suitable cryogenic properties such as low freezing points and viscosities to operate aircraft engines in harsh conditions. − For example, JP-10 ( exo -isomer of tetrahydrodicyclopentadiene) is the synthetic fuel that can give 13–14% more energy in comparison to distilled kerosene. − In recent years, various synthetic fuels have been developed, for instance, fully hydrogenated and isomerized tricyclopentadiene, , cyclopropanated terpenes, − alkyladamantanes, , hydrogenated dimers of norbornene and norbornadiene, , dimers of isoprene and myrcene, etc.…”