Synthesis of high-density flammable hydrocarbon as potential hypergolic fuel and ignition additive of high-density fuels

Flammable liquid fuels are potential candidates to replace hydrazine derivatives as hypergolic fuel and to promote ignition and combustion of high-density fuels as additives. Here 1,4-dicyclopropylbuta-1,3-diyne (DCPB) with high density (0.932 g/mL) and net heating value (42.47 MJ/kg) was synthesized by simple copper-catalyzed alkyne coupling reaction. As hypergolic fuel, DCPB has a short ignition delay time of 19 ± 0.11 ms when contacting with fuming nitric acid. The calculated enthalpy of formation (ΔfH) of DCPB and specific impulse (Isp) using O2(L), N2O4(L) and HNO3(L) as oxidants are 499.2 kJ/mol, 394.7 s, 355.4 s and 334.7 s, respectively, much higher than that of hydrazine (50.9 kJ/mol, 379.0 s, 350.2 s and 333.5 s). The high Isp and short ignition delay time supported DCPB can be used as hypergolic fuel. As ignition additive, high temperature droplet plate and shock tube tests confirm that DCPB is effective to reduce the ignition delay time and lower the apparent ignition activation energy of high-density fuels like JP-10. Therefore, DCPB can be used as potential hypergolic fuel and ignition additive of high-density fuel.