Synthesis and fuel properties of high-density and low-freezing-point asymmetric cycloalkyl adamantane

The exploration to increase the fuel energy density is stimulated by the payload and cruising range concerns in aerospace industry. The high-density fuels are always rationally designed for the advanced volume-limited aircrafts to fulfill more complicated missions. Alkyl adamantanes gradually become a prospective class of high-energy-density fuels. Herein, in this work, we reported an approach to synthesize asymmetric cyclopentyl adamantane via AlCl3-catalyzed alkylation of adamantane and cyclopentene with an attractive combination of a high density of 0.990 g/mL as well as a low freezing point of-30 degrees C. The obtained 1-cyclopentyl-adamantane was well designed with the cyclic substituent (enhance the density) and asymmetric structure (lower the freezing temperature). Subsequently, the comprehensive fuel performance of cyclopentyl adamantane, i.e., density, freezing point, low-temperature viscosity, heating value, and combustion properties were evaluated. It was shown that both density and combustion properties of cycloalkyl adamantane were superior to the typical high -density JP-10 fuel. In addition, the properties of binary fuel mixture (1-cyclopentyl-adamantane and JP-10) demonstrated that cyclopentyl adamantane could be used as a promising blendstock with conventional jet fuel to enhance the energy density and promote the combustion performance of the final fuel blends.

Automated summary

The exploration of increasing fuel energy density is driven by concerns about payload and cruising range in the aerospace industry. High-density fuels are designed for advanced volume-limited aircraft to fulfill complex missions, and alkyl adamantanes are promising candidates for high-energy-density fuels. This work reports the synthesis of asymmetric cyclopentyl adamantane with a high density of 0.990 g/mL and a low freezing point of -30°C via AlCl3-catalyzed alkylation. The comprehensive fuel performance evaluation shows that cyclopentyl adamantane has superior density and combustion properties compared to the typical high-density JP-10 fuel, and can be blended with conventional jet fuel to enhance energy density and combustion performance.