Decalin is considered as an important compound of high-energy-density endothermic fuel,which is an ideal on-board coolant for thermal management of advanced aircraft.However,decalin contains two isomers with a tunable...Decalin is considered as an important compound of high-energy-density endothermic fuel,which is an ideal on-board coolant for thermal management of advanced aircraft.However,decalin contains two isomers with a tunable composition,and their effects on the pyrolysis performance,such as the heat sink and coking tendency have not been demonstrated.Herein,we investigated the pyrolysis of decalin isomers,i.e.,cis-decalin,trans-decalin and their mixtures(denoted as mix-decalin),in order to clarify the effects of the cis-/trans-structures on the pyrolysis performance of decalin fuels.The pyrolysis results confirmed that conversion of the tested fuels(600–725℃,4 MPa)decreased in the order cis-decalin>mix-decalin>trans-decalin.Detailed analyses of the pyrolysis products were used to compare the product distributions from cis-decalin,mix-decalin and trans-decalin,and the yields of some typical components(such as cyclohexene,1-methylcyclohexene,benzene and toluene)showed significant differences,which could be ascribed to deeper cracking of cis-decalin.Additionally,the heat sinks and coking tendencies of the decalins decreased in the order cis-decalin>mix-decalin>trans-decalin.This work demonstrates the relationship between the cis/trans structures and the pyrolysis performance of decalin,which provides a better understanding of the structure-activity relationships of endothermic hydrocarbon fuels.展开更多
采用共沉淀法制备了Zr0.5Ti0.5O2载体材料,将其掺杂在CeO2-Al2O3(CA)基催化剂中,并对其催化活性进行了超临界裂解测试,采用全自动吸附仪、X射线衍射(XRD)、透射电镜(TEM)、程序升温脱附(TPD)等方法对催化剂进行了表征.实验结果表明,催...采用共沉淀法制备了Zr0.5Ti0.5O2载体材料,将其掺杂在CeO2-Al2O3(CA)基催化剂中,并对其催化活性进行了超临界裂解测试,采用全自动吸附仪、X射线衍射(XRD)、透射电镜(TEM)、程序升温脱附(TPD)等方法对催化剂进行了表征.实验结果表明,催化剂能够明显降低裂解反应的温度,600°C CA基催化剂产气率是热裂解的2.8倍,掺杂Zr0.5Ti0.5O2载体材料的CA基催化剂是热裂解的4.0倍,650°C时,掺杂Zr0.5Ti0.5O2载体材料的CA基催化剂热沉提高了0.55 MJ kg 1.BET结果表明,掺杂Zr0.5Ti0.5O2载体后催化剂出现双孔结构,部分小孔的出现使得乙烯的选择性提高;NH3-TPD结果表明,掺杂Zr0.5Ti0.5O2载体材料后,催化剂强酸位的酸量增加了4.0倍,催化剂表现出更强的表面酸性和更集中的强酸酸中心密度,有利于裂解多产烯烃.展开更多
Endothermic hydrocarbon fuel is regarded as an optimal fuel for a scramjet with regenerative cooling,which provides extra cooling through endothermic chemical conversion to avoid the severly limited cooling capacity w...Endothermic hydrocarbon fuel is regarded as an optimal fuel for a scramjet with regenerative cooling,which provides extra cooling through endothermic chemical conversion to avoid the severly limited cooling capacity when conventional fuels are adopted for cooling.Although endothermic cooling is proposed from the view point that the heat sink of a conventional fuel is insufficient,the heat-absorbing through endothermic chemical reaction is actually a chemical recuperation process because the wasted heat dissipated from the engine thermal structure is recovered through the endothermic chemical reaction.Therefore,the working process of a scramjet with endothermic hydrocarbon fuel cooling is a chemical recuperative cycle.To analyze the chemical recuperative cycle of a chemically recuperated scramjet engine,we defined physical and chemical recuperation effectivenesses and heating value increment rate,and derived engine performance parameters with chemical recuperation.The heat value benefits from both physical and chemical recuperations,and it increases with the increase in recuperation effectiveness.The scramjet performance parameters also increase with the increase in chemical recuperation effectiveness.The increase in chemical recuperation effectiveness improves both the performances of the fuel cooling system and the combustion system.The results of analysis prove that the existence of a chemical recuperation process greatly improves the performance of the whole scramjet.展开更多
基金support from the National Key R&D Program of China(Grant No.2021YFC2103701)the Haihe Laboratory of Sustainable Chemical Transformations for financial support,the Postdoctoral Science Foundation of China(Grant No.2021M702810)the National Natural Science Foundation of China(Grant No.22208295)。
文摘Decalin is considered as an important compound of high-energy-density endothermic fuel,which is an ideal on-board coolant for thermal management of advanced aircraft.However,decalin contains two isomers with a tunable composition,and their effects on the pyrolysis performance,such as the heat sink and coking tendency have not been demonstrated.Herein,we investigated the pyrolysis of decalin isomers,i.e.,cis-decalin,trans-decalin and their mixtures(denoted as mix-decalin),in order to clarify the effects of the cis-/trans-structures on the pyrolysis performance of decalin fuels.The pyrolysis results confirmed that conversion of the tested fuels(600–725℃,4 MPa)decreased in the order cis-decalin>mix-decalin>trans-decalin.Detailed analyses of the pyrolysis products were used to compare the product distributions from cis-decalin,mix-decalin and trans-decalin,and the yields of some typical components(such as cyclohexene,1-methylcyclohexene,benzene and toluene)showed significant differences,which could be ascribed to deeper cracking of cis-decalin.Additionally,the heat sinks and coking tendencies of the decalins decreased in the order cis-decalin>mix-decalin>trans-decalin.This work demonstrates the relationship between the cis/trans structures and the pyrolysis performance of decalin,which provides a better understanding of the structure-activity relationships of endothermic hydrocarbon fuels.
文摘采用共沉淀法制备了Zr0.5Ti0.5O2载体材料,将其掺杂在CeO2-Al2O3(CA)基催化剂中,并对其催化活性进行了超临界裂解测试,采用全自动吸附仪、X射线衍射(XRD)、透射电镜(TEM)、程序升温脱附(TPD)等方法对催化剂进行了表征.实验结果表明,催化剂能够明显降低裂解反应的温度,600°C CA基催化剂产气率是热裂解的2.8倍,掺杂Zr0.5Ti0.5O2载体材料的CA基催化剂是热裂解的4.0倍,650°C时,掺杂Zr0.5Ti0.5O2载体材料的CA基催化剂热沉提高了0.55 MJ kg 1.BET结果表明,掺杂Zr0.5Ti0.5O2载体后催化剂出现双孔结构,部分小孔的出现使得乙烯的选择性提高;NH3-TPD结果表明,掺杂Zr0.5Ti0.5O2载体材料后,催化剂强酸位的酸量增加了4.0倍,催化剂表现出更强的表面酸性和更集中的强酸酸中心密度,有利于裂解多产烯烃.
基金supported by the National Natural Science Foundation of China (General Program) (Grant No. 51106037)the Distinguished Young Scholars (Grant No. 50925625)the Innovative Research Groups(Grant No. 51121004)
文摘Endothermic hydrocarbon fuel is regarded as an optimal fuel for a scramjet with regenerative cooling,which provides extra cooling through endothermic chemical conversion to avoid the severly limited cooling capacity when conventional fuels are adopted for cooling.Although endothermic cooling is proposed from the view point that the heat sink of a conventional fuel is insufficient,the heat-absorbing through endothermic chemical reaction is actually a chemical recuperation process because the wasted heat dissipated from the engine thermal structure is recovered through the endothermic chemical reaction.Therefore,the working process of a scramjet with endothermic hydrocarbon fuel cooling is a chemical recuperative cycle.To analyze the chemical recuperative cycle of a chemically recuperated scramjet engine,we defined physical and chemical recuperation effectivenesses and heating value increment rate,and derived engine performance parameters with chemical recuperation.The heat value benefits from both physical and chemical recuperations,and it increases with the increase in recuperation effectiveness.The scramjet performance parameters also increase with the increase in chemical recuperation effectiveness.The increase in chemical recuperation effectiveness improves both the performances of the fuel cooling system and the combustion system.The results of analysis prove that the existence of a chemical recuperation process greatly improves the performance of the whole scramjet.
