Methylcyclohexane(MCH)serves as an ideal hydrogen carrier in hydrogen storage and transportation process.In the continuous production of hydrogen from MCH dehydrogenation,the rational design of energy-efficient cataly...Methylcyclohexane(MCH)serves as an ideal hydrogen carrier in hydrogen storage and transportation process.In the continuous production of hydrogen from MCH dehydrogenation,the rational design of energy-efficient catalytic way with good performance remains an enormous challenge.Herein,an internal electric heating(IEH)assisted mode was designed and proposed by the directly electrical-driven catalyst using the resistive heating effect.The Pt/Al2O_(3)on Fe foam(Pt/Al2O_(3)/FF)with unique threedimensional network structure was constructed.The catalysts were studied in a comprehensive way including X-ray diffraction(XRD),scanning electron microscopy(SEM)-mapping,in situ extended X-ray absorption fine structure(EXAFS),and in situ COFourier transform infrared(FTIR)measurements.It was found that the hydrogen evolution rate in IEH mode can reach up to above 2060 mmol·gPt^(−1)·min^(−1),which is 2–5 times higher than that of reported Pt based catalysts under similar reaction conditions in conventional heating(CH)mode.In combination with measurements from high-resolution infrared thermometer,the equations of heat transfer rate,and reaction heat analysis results,the Pt/Al2O_(3)/FF not only has high mass and heat transfer ability to promote catalytic performance,but also behaves as the heating component with a low thermal resistance and heat capacity offering a fast temperature response in IEH mode.In addition,the chemical adsorption and activation of MCH molecules can be efficiently facilitated by IEH mode,proved by the operando MCH-FTIR results.Therefore,the as-developed IEH mode can efficiently reduce the heat and mass transfer limitations and prominently boost the dehydrogenation performance,which has a broad application potential in hydrogen storage and other catalytic reaction processes.展开更多
In this paper, the dispersion and nucleation behavior of ultrafine particles of silica and layered silicate (LS) in poly(ethylene terephthalate) (PET) matrix are investigated and characterized by Transmission Electron...In this paper, the dispersion and nucleation behavior of ultrafine particles of silica and layered silicate (LS) in poly(ethylene terephthalate) (PET) matrix are investigated and characterized by Transmission Electron Microscopy (TEM), Wide Angle X-ray Diffraction (WAXD), Dynamic Scanning Calorimetry (DSC), and Atomic Force Microscopy (AFM). The solid precursors based on silica and LS are suggested originally for preparing nanocomposites with good dispersion morphology. Results show that the initial sub-micron (1000~500 nm) LS particles are exfoliated or dispersed into nanometer-scale particles (30~70 nm) during their polymerization with PET monomers. These dispersed nanoparti-cles form an ordered morphology in their nucleation and growth during annealing nanocomposites. DSC patterns reveal that the double melting peaks of annealed PET-LS nanocomposites disappear, while they have shrunken in PET-silica ones. These findings strongly demonstrate that the dispersed nanoparticles accelerate the crystallization of PET. The dispersed LS particles have higher percolation and nucleation performance than those of silica. The homogeneous distribution morphology of ultrafine particles is easily obtained by controlling the load of their cor-responding precursors. Such a dispersion obviously improves PET properties in that its heat distortion temperature (HDT) increases from 76℃ to 103℃, and crystallization increases 2~4 times more than that of PET. Especially, the nanocom-posite films keep themselves transparent when particle load is within 2 wt.% though there are 3 wt.% or so of agglomer-ated particles in the nanocomposites.展开更多
基金the National Natural Science Foundation of China(Nos.22225807,21961132026,21878331,22021004,and 22109177)the National Key Research and Development Program(Nos.2020YFA0210903 and 2021YFA1501304)+4 种基金the PetroChina research institute of petroleum processing program(Nos.PRIKY21057 and PRIKY 21199)the Fundamental Research Funds for the Central Universities(No.2462020BJRC008)the support of Energy Internet Research Center,China University of Petroleum(Beijing),Haihe Laboratory of Sustainable Chemical Transformations(No.CYZC202105)the Beijing Synchrotron Radiation Facility(BSRF)Shanghai Synchrotron Radiation Facility(SSRF)during the XAFS measurements at the beamline of 1W1B,1W2B,and BL11B.
文摘Methylcyclohexane(MCH)serves as an ideal hydrogen carrier in hydrogen storage and transportation process.In the continuous production of hydrogen from MCH dehydrogenation,the rational design of energy-efficient catalytic way with good performance remains an enormous challenge.Herein,an internal electric heating(IEH)assisted mode was designed and proposed by the directly electrical-driven catalyst using the resistive heating effect.The Pt/Al2O_(3)on Fe foam(Pt/Al2O_(3)/FF)with unique threedimensional network structure was constructed.The catalysts were studied in a comprehensive way including X-ray diffraction(XRD),scanning electron microscopy(SEM)-mapping,in situ extended X-ray absorption fine structure(EXAFS),and in situ COFourier transform infrared(FTIR)measurements.It was found that the hydrogen evolution rate in IEH mode can reach up to above 2060 mmol·gPt^(−1)·min^(−1),which is 2–5 times higher than that of reported Pt based catalysts under similar reaction conditions in conventional heating(CH)mode.In combination with measurements from high-resolution infrared thermometer,the equations of heat transfer rate,and reaction heat analysis results,the Pt/Al2O_(3)/FF not only has high mass and heat transfer ability to promote catalytic performance,but also behaves as the heating component with a low thermal resistance and heat capacity offering a fast temperature response in IEH mode.In addition,the chemical adsorption and activation of MCH molecules can be efficiently facilitated by IEH mode,proved by the operando MCH-FTIR results.Therefore,the as-developed IEH mode can efficiently reduce the heat and mass transfer limitations and prominently boost the dehydrogenation performance,which has a broad application potential in hydrogen storage and other catalytic reaction processes.
文摘In this paper, the dispersion and nucleation behavior of ultrafine particles of silica and layered silicate (LS) in poly(ethylene terephthalate) (PET) matrix are investigated and characterized by Transmission Electron Microscopy (TEM), Wide Angle X-ray Diffraction (WAXD), Dynamic Scanning Calorimetry (DSC), and Atomic Force Microscopy (AFM). The solid precursors based on silica and LS are suggested originally for preparing nanocomposites with good dispersion morphology. Results show that the initial sub-micron (1000~500 nm) LS particles are exfoliated or dispersed into nanometer-scale particles (30~70 nm) during their polymerization with PET monomers. These dispersed nanoparti-cles form an ordered morphology in their nucleation and growth during annealing nanocomposites. DSC patterns reveal that the double melting peaks of annealed PET-LS nanocomposites disappear, while they have shrunken in PET-silica ones. These findings strongly demonstrate that the dispersed nanoparticles accelerate the crystallization of PET. The dispersed LS particles have higher percolation and nucleation performance than those of silica. The homogeneous distribution morphology of ultrafine particles is easily obtained by controlling the load of their cor-responding precursors. Such a dispersion obviously improves PET properties in that its heat distortion temperature (HDT) increases from 76℃ to 103℃, and crystallization increases 2~4 times more than that of PET. Especially, the nanocom-posite films keep themselves transparent when particle load is within 2 wt.% though there are 3 wt.% or so of agglomer-ated particles in the nanocomposites.
