Solubilization of the macroinitiator palmitoyl modified hyperbranched polyglycerol (PHPG) in hydrocarbon fuels

•Aggregation-dispersion of PHPG in hydrocarbons is systematically investigated.•Solubility of PHPG in fuels is enhanced dramatically by alcohols as co-surfactants.•PHPG solubilized by alcohols can further improve the heat sink of hydrocarbons.

Palmitoyl-modified hyperbranched polyglycerol (PHPG), has been developed as a kind of “macroinitiator” for improving the endothermic capability of hydrocarbon fuels. As the solubilization of the macroinitiator in hydrocarbon fuels is essential to its application in practical operations, the solubility of PHPG in a series of n-alkane is evaluated theoretically via the change of Gibbs free energy in the mixing process, and is verified experimentally by the tests on the transmittance with a UV-vis spectrophotometer. The dissolution-aggregation behavior of PHPG with different molecular weights in tridecane solutions is investigated by the dynamic laser scattering (DLS) technique. n-Alcohols are applied as co-surfactants to improve the solubility of PHPG in hydrocarbon fuels. The upper critical solution temperatures (UCST) of PHPG in tridecane with the addition of alcohols are successfully lowered, and the particle sizes detected by DLS are much lower than those without alcohols. Then, the endothermic capabilities of a series of tridecane-based fuels under supercritical conditions (3.5 MPa, and 600-720 °C) are investigated in a tube reactor which is heated by a direct current. The conversion, gas yield and heat sink of each fuel in the cracking process are obtained. It is showed that the PHPG can initiate the cracking of hydrocarbon fuels and enhance their endothermic capability significantly. With the addition of alcohols, not only the solubility of PHPG in hydrocarbon fuels is improved significantly, but also the heat sink of hydrocarbons is further raised to a higher value.

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