Preparation Of Nano-Pt And It’s Influence On Ignition Characteristics Of Iso-octane

As a new type of combustion technology,catalytic combustion has great potential in solving the problem of supersonic combustion.In this paper,based on the rapid compression machine system,the ignition characteristics of large hydrocarbon fuel iso-octane under the catalysis of Nano-Pt are studied,which provides theoretical guidance for solving the problem of low temperature ignition of ramjets.Firstly,an atomization system suitable for liquid fuel is designed.The liquid fuel can form a stable aerosol system after being atomized by the atomizing nozzle,which solves the problem that the fuel cannot be effectively evaporated and mixed at low temperature due to low saturated vapor pressure,provides a prerequisite for follow-up study.Secondly,Pt nanoparticles encapsulated by three protective ligands,oleylamine,dodecylamine and octadecylamine,were synthesized using the classical Brust-Schiffrin method in an inert atmosphere glove box.Field emission transmission electron microscopy,X-ray diffraction,thermogravimetric analysis,and Fourier transform infrared spectroscopy were used for characterization and analysis.The analysis results showed that the change trend of the average particle size of the nanoparticles decreased first and then increased with the increase of the molar ratio.When the ligand molar ratio X=2,the average particle size is the smallest.The minimum average particle size was 2.14 nm for oleylamine,2.44 nm for dodecylamine and 2.63 nm for octadecylamine ligands;with the increase of the molar ratio of ligand,the protective ligand on the surface of Nano-Pt increases;the vibration peaks of ligand functional groups were observed on the surface of Nano-Pt,indicating that the ligands have been effectively wrapped on the surface of Nano-Pt.Then,the ignition characteristics of iso-octane fuel were studied by experiment and kinetic analysis,and the ignition delay time of iso-octane under different temperature,pressure and equivalence ratio conditions was obtained,and the experimental results were in good agreement with the simulation results.The research results show that the ignition delay time shortens with the increase of the initial pressure;outside the NTC range(719～810K),the ignition delay time shortens with the increase of the initial temperature,and in the NTC range,it increases with the increase of the temperature;When the temperature and pressure are constant,the ignition delay time decreases with the equivalence ratio increases.The two-stage ignition phenomenon and NTC phenomenon were explained by reaction path analysis and temperature sensitivity analysis,and the main reaction paths of isooctane under high and low temperature conditions were analyzed.Finally,the Nano-Pt catalytic combustion experiment was carried out on the rapid compression machine system.The experimental results show that Nano-Pt can effectively shorten the ignition delay time of the fuel,increase the first-order ignition intensity,and broaden the low-temperature ignition limit.Under different initial pressures,temperatures and equivalence ratios,Nano-Pt can effectively shorten the total ignition delay time,among which the first-order ignition delay time is shortened by about 50%;the higher the concentration of nano-Pt is,the better the catalytic combustion-supporting effect is,but the reduction of ignition delay time decreases with the increase of concentration.