Isomerization of endo- to exo-tetrahydrotricyclopentadiene over alumino-silicate catalysts

Bio‐Based Cycloalkanes: The Missing Link to High‐Performance Sustainable Jet Fuels

“…Dehydration of 6 to 7 over H‐USY gave the best results (93.8 % yield). Self‐Diels‐Alder cycloaddition of cyclopentadiene yielded dicyclopentadiene in 95.5 % yield over 2 h. As previously reported, [130–135] two‐step hydrogenation of 8 to 9 , under optimized conditions (RT, 4 MPa H 2 , 3 h), proceeded with 97.5 % yield. Although 9 has a high density (0.894 g mL −1 ), it suffers from a high freezing point (77 °C) [136] .…”

High-Energy-Density Liquid Spiro-Norbornanes from Methylenenorbornane

“…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.…”

“…The presence of three or four-membered cycle rings in a hydrocarbon usually improves the gravimetric heat of combustion and low-temperature properties. − At the same time, such fuels exhibit low or moderate values of density and volumetric heat of combustion. High values of density and volumetric heat of combustion can be reached when using norbornane compounds ( exo -tetrahydrodicyclopentadiene, isomerized tetrahydrotricyclopentadiene, bis-norbornanyl). However, the increase in the number of norbornane rings in a hydrocarbon fuel molecule greatly elevates freezing temperatures and viscosity.…”