PROGRESS IN REACTION KINETICS AND MECHANISM
·
2017
·
IF 0.682
Hua Song,Shengnan Li,Hualin Song,Feng Li,Huapeng Cui
A number of Zn–S2O82–/ZrO2–Al2O3 (Zn(x)–SZA) catalysts with different Zn mass fractions were synthesised and characterised by using X-ray diffraction, the Brunauer–Emmett–Teller method, and H2 temperature-programmed reduction. The structure and isomerisation performance of Zn(x)–SZA catalysts were studied using n-pentane as a probe reaction. The results showed that a pure tetragonal ZrO2 phase was formed on Zn(x)–SZA, and the ZrO2 crystallite sizes of the tetragonal phase increased in the order: Zn(0.5)–SZA < Zn(1.0)–SZA < Zn(1.5)–SZA < Zn(2.0)–SZA < SZA. Zn can strengthen the interaction between persulfate ions and the support, promote the formation of stronger acidity, lead to a better dispersion of sulfate ions on the surface, and improve the redox performance of the catalysts. The Zn(1.0)–SZA catalyst exhibited the best catalytic activity for n-pentane isomerisation. At a temperature of 170 °C, a reaction pressure of 2.0 MPa, a molar H2/n-pentane ratio of 4:1, and a weight hourly space velocity of 1.0 h−1, the isopentane yield reached 58.0%.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
FLUID PHASE EQUILIBRIA
·
2024
·
IF 2.8
Tao Jia,Weixue Jiang,Jia Yu
The compressed liquid densities of n -pentane(1) + n -dodecane(2) binary mixtures were measured using a high pressure vibrating-tube densimeter at temperatures from 283 K to 363 K, pressures up to 100 MPa, and five different compositions ( x 1 = 0.3778, 0.6230, 0.7968, 0.9051, and 1). The densities of binary mixtures were correlated using the modified Tait equation, and the absolute average deviations of the experimental and calculated values were 0.010 %, 0.019 %, 0.016 %, 0.025 %, and 0.017 %, respectively. In addition, the isothermal compressibility and the isobaric thermal expansivity were calculated from the obtained densities.
研究领域:
物理化学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
FLUID PHASE EQUILIBRIA
·
2019
·
IF 2.514
Ying Zhang,Qi Zhou,Taotao Zhan,Junshuai Chen,Maogang He
n -Pentane is one of the main components in many industrial fluids, and is widely used as the fuel. The speed of sound can be used for developing the Helmholtz energy formulation and calculating other thermodynamic properties, which has not been reported yet for supercritical n -pentane. In this paper, the speed of sound in supercritical n -pentane was measured by the Brillouin light scattering (BLS) technique within the temperature limits of (422.69–653.53) K along four isobars at p = (3.5, 6.0, 8.0, and 10.0) MPa. The relative uncertainty of our BLS experimental system is estimated to be less than 0.6% and the relative uncertainty of the reported speed of sound values is estimated to be 0.85% considering the influence of impurities in the sample. The dependences of the speed of sound on temperature and pressure were also analyzed. At the end, we compared the experimental data with the calculated values from the multiparameter EOS proposed by Span and Wagner and the Modified BWR EOS proposed by J. Ratanapisit and J.F. Ely. The AARD is 1.3% for the multiparameter EOS and 1.5% for the Modified BWR EOS, respectively.
研究领域:
物理化学
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工程热物理
✓ 已验证
产品关联
DOI
高影响因子
AICHE JOURNAL
·
2022
·Vol. 68
·期 7
·e17677
·
IF 4.167
Shen Hu,Jiaxuan Chen,Qunfeng Zhang,Junru Liu,Jinlin Meng,Guanghua Ye,Xinggui Zhou,Weikang Yuan
Surface barriers persist in the molecular transport across external crystal surface of zeolites, which brings strong influences on zeolite catalysis. This study probes the role of crystal-size–dependent surface barriers in zeolite catalysis, with n -pentane isomerization catalyzed by Pt/ZSM-5 as a model reaction system. Chemical liquid deposition of SiO 2 is performed to reduce surface barriers on ZSM-5 crystals with different sizes. After SiO 2 deposition, surface barriers on both small (266 nm) and large (1304 nm) crystals are significantly reduced, while the improvement in catalytic activity for the large crystals (76.1%–129.1%) is much higher than that for the small ones (−17.4% to 16.7%). For the large ZSM-5 crystals, diffusion limitation is stronger, and thus the effect of surface barriers on catalytic activity is more important. This study reveals the unique role of crystal-size–dependent surface barriers in zeolite catalysis, and understanding this is important for the optimal design of zeolite catalysts.
研究领域:
化学工程
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材料科学
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
PROCEEDINGS OF THE COMBUSTION INSTITUTE
·
2016
·
IF 4.12
Anne Rodriguez,Olivier Herbinet,Zhandong Wang,Fei Qi,Christa Fittschen,Phillip R. Westmoreland,Frédérique Battin-Leclerc
The reactions of chain-branching agents, such as H 2 O 2 and hydroperoxides, have a decisive role in the occurrence of autoignition . The formation of these agents has been investigated in an atmospheric-pressure jet-stirred reactor during the low-temperature oxidation of n- pentane (initial fuel mole fraction of 0.01, residence time of 2 s) using three different diagnostics: time-of-flight mass spectrometry combined with tunable synchrotron photoionization, time-of-flight mass spectrometry combined with laser photoionization, and cw- cavity ring-down spectroscopy. These three diagnostics enable a combined analysis of H 2 O 2 , C 1 –C 2 , and C 5 alkylhydroperoxides, C 3 –C 5 alkenylhydroperoxides, and C 5 alkylhydroperoxides including a carbonyl function (ketohydroperoxides). Results using both types of mass spectrometry are compared for the stoichiometric mixture. Formation data are presented at equivalence ratios from 0.5 to 2 for these peroxides and of two oxygenated products, ketene and pentanediones, which are not usually analyzed during jet-stirred reactor oxidation. The formation of alkenylhydroperoxides during alkane oxidation is followed for the first time. A recently developed model of n- pentane oxidation aids discussion of the kinetics of these products and of proposed pathways for C 3 –C 5 alkenylhydroperoxides and the pentanediones.
研究领域:
化学动力学
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燃烧科学
·
光谱分析
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2023
·
IF 4.4
Bingzhi Liu,Qimei Di,Maxence Lailliau,Nesrine Belhadj,Philippe Dagaut,Zhandong Wang
Attractiveness in advanced low-temperature combustion engines drives a constantly updated understanding of low-temperature oxidation chemistry. In this work, the low-temperature oxidation chemistry of n -pentane in two jet-stirred reactors at atmospheric pressure and in the temperature range of 500–825 K was investigated using combined analysis methods of synchrotron vacuum ultraviolet photoionization mass spectrometry , gas chromatography, and Fourier transform infrared spectroscopy. Furthermore, the gaseous mixture from JSR was collected in acetonitrile for subsequent product characterization using flow injection analysis , high-pressure and ultra-high-pressure liquid chromatography coupled to a Thermo Scientific™ Orbitrap® Q-Exactive high-resolution mass spectrometry. Numerous intermediate species were identified by these analytical methods, which contributed to unraveling the low-temperature oxidation reaction network of n -pentane. A detailed n -pentane model was tentatively developed to reduce deviations between experimental measurements and model predictions by updating the rate constants of C 5 keto-hydroperoxide decomposition, C 5 hydroperoxy cyclic ether decomposition, and Korcek reactions of C 5 keto-hydroperoxide, and by introducing pressure-dependent rate constants for the reaction classes of Q ˙ OOH + O 2 , Q ˙ OOH decompositions, concerted HȮ 2 -elimination of RȮ 2 , C 5 keto-hydroperoxide decomposition, C 5 hydroperoxy cyclic ether decomposition, and Korcek reactions of C 5 keto-hydroperoxide, and by adding more detailed sub-mechanisms for C 5 cyclic ethers and C 5 keto-hydroperoxides. This updated model was validated against a set of available experimental data, including jet-stirred reactor species data and ignition delay times. These exploratory updates of the kinetic model reveal the considerable influence of the rate constants of hydroperoxide decomposition and the pressure-dependent rate constants of key reaction classes on the kinetic model predictions, highlighting the future demands for high-precision quantum chemistry calculations of the pressure-dependent rate constants of the aforementioned reaction classes to reduce mechanism uncertainties and to develop accurate and robust chemical kinetic models.
研究领域:
化学动力学
·
燃烧科学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
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