Strategically Designed Hyperbranched Polyglycerol as an Efficient Integrated Additive for Hydrocarbon Fuels

In this study, palmitoyl and hindered phenolic hyperbranched polyglycerol (CBHPG), with hyperbranched polyglycerol (HPG) as the structural core and hindered phenol or alkyl chain as the decorated shell, has been strategically designed and synthesized as an efficient integrated additive to enhance the energy efficiency and inhibit the oxidation coking of hydrocarbon fuels. The superior thermal stability and solubility of CBHPG were confirmed by thermal gravimetric analysis and dynamic light scattering. In the presence of CBHPG with high antioxidant activity, the oxidation induction time of n-undecane increased more than 2-fold at 170 °C. In deposition tests, the amphiphilic macromolecule CBHPG showed excellent performance with 58% oxidation coking inhibition rate of Chinese Jet Fuel (RP-3). The Jet Fuel Thermal Oxidation Stability test at 355 °C also exhibited that CBHPG could greatly reduce the deposit of RP-3 by decreasing the deposit rating from >4 to <1. In cracking experiments, the addition of 0.1 wt % CBHPG with sufficient polymerization could increase the conversion of n-undecane by 17.6%, with the corresponding heat sink by 6.1% at 675 °C. The above results indicated that CBHPG could efficiently enhance the performance of hydrocarbon fuels due to multipurposes in antioxidation, coking inhibition, and cracking promotion. CBHPG with a strategically designed structure as an integrated additive shows great promise in improving the energy efficiency and safety in future advanced aircraft

Calixarene-Capped Platinum Nanofluid for Pseudohomogeneous Catalytic Cracking and Heat Sink Enhancement of Ethylcyclohexane

To solve the heat management problem of supersonic aircraft, endothermic hydrocarbon fuels (EHFs) have been developed as both a coolant and a propellant. The pseudohomogeneous catalyst is an efficient way to improve the heat sink of EHFs. In this work, hydrocarbon soluble macrocyclic calixarene compound C-undecyl calix[4]2-(propylsulfanylmethyl)-resonrcinarene (C11–SC3) was synthesized and used as a stabilizer for hydrocarbon-dispersed Pt nanoparticles (Pt@C11–SC3). The morphological characterization results indicate that Pt nanoparticles are encapsulated by the calixarene, which helps the fabrication of ultrasmall Pt@C11–SC3. Ethylcyclohexane (ECH) was selected as a model substrate of EHFs to construct the Pt@C11–SC3/ECH nanofluid system for pseudohomogeneous catalytic cracking. The cracking test of the Pt@C11–SC3/ECH nanofluid was carried out in a batch reactor and a flow reactor under constant volume and pressure conditions. The distribution of cracking products displayed a significant improvement in terms of cracking conversion and a preferred heat absorbed reaction pathway, leading to a higher heat sink. There was a 16% maximum increase in heat sink in the constant pressure cracking tests with the addition of 0.01 wt % Pt@C11–SC3 at 700 °C. It provides a helpful method for heat sink enhancement of EHFs