Thermodynamic properties and pyrolysis performances of hydrocarbon-fuel-based nanofluids containing palladium nanoparticles

• Surface-modified Pd nanoparticles were synthesized with diameters of 1–3 nm.
• Nanofluids were prepared with Pd NPs and decalin/kerosene.
• Viscosity, thermal conductivity and stability of nanofluids are determined.
• Pd NPs possess catalytic ability for the pyrolysis of hydrocarbon fuel.
• Pd@S(Viscosit)&N is the most potential additive for the hydrocarbon fuel.

AbtractThree different kinds of palladium nanoparticles (Pd NPs) modified by octadecanethiol, octadecylamine, and mixture of them have been prepared, which are simply marked as Pd@S, Pd@N and Pd@S&N in turn. The average diameters of Pd NPs are 1–3 nm. The Pd NPs can be well-dispersed in decalin and kerosene. The properties of the kerosene-based nanofluids, such as viscosities, thermal conductivities and stabilities are determined. The pyrolysis of decalin-based nanofluids containing Pd NPs is carried out in a batch reactor from 440 to 470 °C. The order of the catalytic ability for three Pd NPs is: Pd@N > Pd@S&N > Pd@S. The catalytic abilities of Pd NPs for pyrolysis of decalin are ascribed to the combined effects of Pd and its ligands. Based on GC analysis results, the major gaseous products are found to be methane, ethane, ethylene, propane and propylene. The liquid products contain aromatic, cycloalkene, cycloalkane, and chain hydrocarbons. The amount of chain hydrocarbons is small at different reaction temperatures, which means ring-opening reaction is difficult to occur during the pyrolysis of decalin. The formation of aromatic results from the dehydrogenation and condensation of cycloalkene induced by the secondary reaction at relatively high temperatures. For a comprehensive evaluation of the thermal conductivity, stability and catalytic ability, Pd@S&N is the most potential additive for the hydrocarbon fuel to prepare an advanced propellant with high stability, thermal conductivity and cooling ability.