Catalytic Cracking Of Hydrocarbon Endothermic Fuels In Coated Tube Reactor

As flight speed increases to the high supersonic and hypersonic regime, the temperature of the ram air taken on broad the vehicle becomes too high to cool the structure. Therefore it is necessary to utilize the fuel as the primary coolant. In this work, an investigation was conducted to explore the zeolite coating catalytic cracking of jet fuel model compound (n-dodecane) and the practice fuel (China No.3 kerosene) at supercritical condition. The thickness of the zeolite layer, the heat sink, the mole conversion and the composition of the product of the endothermic fuel (n-dodecane and RP-3) were evaluated.In this study, a kind of binder was synthesized and used H-ZSM5 (Si/Al:50) and HY (Si/Al: 30) as zeolites for coating the reactor. The binder was mixed with zeolite to make suspension. By determined different component of suspension applied for differet configuration substrate. The zeolite H-ZSM5 and HY were loaded on the surface of the stainless steel board and inner wall ofΦ3 stainless reactor tube, Experiments of XRD, FT-IR, SEM and simulative cracking reaction were carried out. The results indicated that the layer thickness kept in 15-25μm and the particle size between 1 to 5μm. The prepared catalyst coating shows good reactivity and stability. The pure n-dodecane was used as the model reactant to estimate the H-ZSM5 and HY coating catalyst. The heat sink and mole conversation of endothermic fuel (n-Dodecane and RP-3) were evaluated under supercritical condition 600°C and 625°C, reaction pressure at 4 MPa and various zeolite and loading. When the HY( 25wt% ) zeolite were coated on the reactor inter wall, it indicated that zeolite-coating increased the heat sink capacity by 815.7kJ/kg at 600°C and by 902.0kJ/kg at 625°C than bare tube. The mole conversation variously increased 17.6% and 12.8%, the hydrogen mole percent increased 0.61% and 1.38% than bare tube. When the H-ZSM5(30wt%)zeolite were coated on the reactor inter wall, it indicated that zeolite-coating increased the heat sink capacity by 564.2kJ/kg at 600°C and by 942.9kJ/kg at 625°C than bare tube. The mole conversation variously increased 19.8% and 25.6%, respectively; the hydrogen mole percent increased 0.38% and 1.77% than bare tube.Practical fuel RP-3 were investigated with the optimal combination of catalyst and binder. The heat sink capacity and gas products mass fraction of RP-3 were dramaticly increased with catalyst. The chemical heat sink can be as high as 2100kJ/kg. According to the experience of Chinese Academic of Science, catalytic cracking could produce 9.27 mol% hydrogen when the reaction temperature was at 750°C by using zeolite coating reaction.The coke deposit of fuel cracking was also investigated. The result indicates that the deposited carbon deposit mainly formed at catalytic cracking sections, the large amount of the deposition carbon formed at the maximal reaction temperature.