COMBUSTION SCIENCE AND TECHNOLOGY
·
2013
·
IF 1.011
Ming-Di Li,Zhong Wang,Yang Zhao,Rui-Na Li,Shuai Liu
An experimental study was reported on premixed ethanol/n-heptane/oxygen/argon flames at low pressure (4.655 kPa) with ethanol blending ratios of 0 (Flame 1), 15% (Flame 2), and 30% (Flame 3). The equivalence ratio was 1.0. Flame species were identified using molecular beam mass spectrometry with tunable synchrotron photoionization. The flame temperature profiles were measured with a Pt-6%Rh/Pt-30%Rh thermocouple. The mole fraction profiles of major and intermediate flame species under different ethanol ratios were analyzed in this article. Experimental results showed that the temperature profiles of measured flames fall almost on a single curve, which means that ethanol had little effect on flame temperature. The peak mole fraction of the main combustion products occurred 2–6 mm above the burner. With the increase of ethanol blending ratios, the mole fractions of H2, CO, and CO2 decreased, the mole fraction of H2O increased, and the mole fractions of intermediate combustion products (C2H2, C2H4, HCHO, C3H3) decreased. During the combustion process, the oxygen atom of ethanol partly replaces the O2, thus the final mole fraction of O2 increased with the increase of ethanol ratios.
研究领域:
化学工程
·
燃烧学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2020
·
IF 2.369
Ying Zhang,Taotao Zhan,Junshuai Chen,Xin Li,Qi Zhou,Maogang He
The experimental speeds of sound for the binary system of ethanol (1) + n-heptane (2) with the mole fractions of ethanol being (0.100, 0.300, 0.500, 0.700, and 0.900) were measured by Rayleigh-Brillouin light scattering spectroscopy at temperatures from 293.35 to 433.89 K along three isobaric lines from 0.1 to 5.0 MPa. The expanded relative uncertainty for the reported speed of sound is estimated to be 1.6% with the level of confidence of 0.95 (coverage factor k = 2). The experimental data were correlated as a function of temperature and pressure, yielding absolute average percentage deviations of 0.34, 0.20, 0.38, 0.28, and 0.29% for the mole fractions of ethanol being 0.100, 0.300, 0.500, 0.700, and 0.900, respectively. Within the temperature limits of 298.15–318.15 K, the derived thermo-acoustic properties for the binary system of ethanol (1) + n-heptane (2), including the density, the specific isobaric heat capacity, the isentropic compressibility, the isobaric thermal expansivity, the isothermal compressibility, the specific heat ratio, the internal pressure and the free volume at pressures up to 5.0 MPa, and the intermolecular free length under atmospheric pressure were calculated and analyzed.
研究领域:
物理化学
·
热力学
✓ 已验证
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2020
·
IF 2.888
Junwei Cui,Shengshan Bi,Andreas P. Fröba,Jiangtao Wu
The present work focus on the measurement of viscosity and interfacial tension of n -heptane ( n -C 7 H 16 ) with dissolved carbon dioxide (CO 2 ) by the surface light scattering. The method allows an absolute determination of both properties in a contactless way. The experiments were conducted in macroscopic thermodynamic equilibrium at temperatures from (298 to 473) K and saturation pressures up to 5.5 MPa. For sample preparation of binary mixtures of n -C 7 H 16 with dissolved CO 2 after its addition, the equilibration process could be checked to be completed by showing that viscosity and interfacial tension are independent on time. For reaching equilibrium, at least two hours were elapsed between the addition of CO 2 and the start of the measurement. For both viscosity and interfacial tension, typical expanded uncertainties are 3% on a confidence level of 95%. The viscosity results were correlated with an empirical equation, where the absolute average deviation (AAD) and the maximum absolute deviation (MAD) between experiments and correlation were 1.9% and 7.2%, respectively. For the viscosity, a data comparison was hindered because of the lack of literature data. For the interfacial tension, which can also be represented by an empirical correlation and good agreement with literature can be found.
研究领域:
物理化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2021
·
IF 6.609
Tao Pan,Sida Ge,Mengnan Yu,Yana Ju,Ran Zhang,Pei Wu,Kuanyu Zhou,Zhijie Wu
Zn modified ZSM-5 zeolite supported Ni bifunctional catalysts were prepared by in-situ hydrothermal synthesis (Zn-Ni-ZSM-5), co-impregnation method (Zn-Ni/ZSM-5) as well as combining in-situ hydrothermal synthesis of Zn-ZSM-5 and sequential impregnation of Ni (Ni/Zn-ZSM-5) and used for the selective converting olefin to aromatics applicable for FCC gasoline hydro-upgrading. The Lewis (L) acid sites generated by ZnOH + species and hydrogenation active sites from Ni 0 species were varied with preparation method, in which their locations at the external surface or micropores of zeolite changed the acid properties of catalysts. Comparing to the Zn-Ni/ZSM-5 from the co-impregnation method, direct in-situ hydrothermal method could incorporate Zn and Ni species within zeolite, which makes the strong interaction between the metal species and the framework Al to form medium-strong L acids (ZnOH + /NiOH + ). This leads to the decrease of ratio of Brønsted acid sites to L acid sites (B/L) from 0.40 to 0.12 and the difficulty in reducing of Ni cations to Ni 0 from 57% to 30% Ni 0 percent. Ni/Zn-ZSM-5 sample prepared by incorporating Zn species into micropores and sequential depositing Ni species at the external surface of zeolite possesses a low B/L ratio similar to Zn-Ni-ZSM-5 (0.20 versus 0.12) but a much higher Ni 0 percent (52% versus 30%). Zn-Ni-ZSM-5 shows closer intimacy between Zn and Ni species comparing to Zn-Ni/ZSM-5 and Ni/Zn-ZSM-5. For the 1-hexene aromatization, the formed iso -alkene at acid sites was quickly saturated to iso -alkanes by the adjacent Ni 0 particles over Ni-Zn-ZSM-5 catalyst in hydrogen steam. However, the location of aromatization active sites (ZnOH + , L acid sites) in micropores and hydrogenation active sites (Ni 0 species) on external surface of Ni/Zn-ZSM-5 makes the tandem conversion of n-alkene → iso -alkene → aromatics, rather than the n-alkene → iso -alkene → iso -alkane. Thus, Zn-Ni-ZSM-5 with close intimacy of ZnOH + and Ni 0 particles shows a high iso -alkane selectivity (27.9% iC 4 + ), while Ni/Zn-ZSM-5 exhibits a high aromatics selectivity (39.6 %) in the conversion of 1-hexene in hydrogen steam. Similar results have also found in the conversion of n-heptane. Here, the control of the intimacy of Zn and Ni in ZSM-5 zeolites has been realized to be a good protocol to adjust the selective conversion of olefins/alkanes to aromatics versus iso -alkanes.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2021
·
IF 3.178
Zhang Youqi,Zhang Qinqin,Xin Hua,Lv Meiheng,Zhang Zhigang
Ionic liquids (ILs) have been extensively used in the separation of alkane + alcohol azeotropes as entrainers by liquid–liquid extraction. n-Butanol is widely added to the fuel because of its high calorific value and low volatility. It is of significance to recovery n-butanol from the azeotropic mixture containing n-butanol. In this work, ionic liquids, formed by combining 17 cations and 12 anions, were screened based on the COSMO-RS model. 1-ethyl-3-methylimidazolium dicyanamide [EMIM][DCA], 1-butyl-3-methylimidazolium dicyanamide [BMIM][DCA] and 1-hexyl-3-methylimidazolium dicyanamide [HMIM][DCA] were selected as entrainers. The liquid–liquid equilibrium data of the ternary system {n-heptane + n-butanol + [EMIM][DCA], n-heptane + n-butanol + [BMIM][DCA], n-heptane + n-butanol + [HMIM][DCA]} were measured at 298.15 K and 101.3 kPa. The quality of experimental data was tested by Othmer-Tobias, Bachman and Hand equations. The distribution coefficient (β) and selectivity (S) were calculated to evaluate the separation effect of the three ILs. The NRTL model was used to correlate liquid–liquid equilibrium experimental data. Finally, quantum mechanics calculations were performed to study the interactions between ILs and n-butanol through the reduced density gradient (RDG) function and quantum theory of atom in the molecule (QTAIM). The results of quantum chemistry calculation showed that the separation of n-butanol and n-heptane mixture by ionic liquids with [DCA] anions were dominated by hydrogen bonding. The research process is devoted to the development of green entrainers.
研究领域:
化学工程
·
量子化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Zhongqi Ren,Hui Yu,Xiaojia Wu,Weidong Liu,Fan Zhang,Shichao Tian,Zhiyong Zhou
The separation of aromatics and aliphatic hydrocarbons is one of the most challenging and energy consuming operations in the petrochemical industry. In this work, two switchable solvents, 1,8-diazabicyclo[5.4.0]undec-7-ene imidazole ([DBU][Im]) and 1,1,3,3-tetramethylguanidine imidazole ([TMG][Im]), were synthesized and used for phase-change separation of toluene from n-heptane. The structures of these two switchable solvents were analyzed by 1 H Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FT-IR) spectroscopy. The miscibility of various components in these two ILs before and after treatment with CO 2 were studied, the results of which indicated that both these two switchable solvents could be utilized to achieve the effective separation of toluene from n-heptane. Among them, [TMG][Im] was preferable to be used at a low toluene content in the initial toluene/n-heptane system through feasibility study. The effects of extraction time, switchable solvent dosage and molar fraction of toluene on separation performance and the reusability were also investigated, demonstrating that [TMG][Im] could be used simply and feasibly for phase-change separating toluene from n-heptane and showed very good reusability and stability. Finally, the mechanism of reversible phase-change extraction process with [TMG][Im] was explored, indicating that the formation of [TMG][ImCO 2 ] could greatly increase the polarity of the switchable solvent, which is conducive to separating toluene and recovering [TMG][Im] by removing CO 2 .
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
THERMOCHIMICA ACTA
·
2018
·
IF 2.189
Chao Su,Chenyang Zhu,Tianwang Lai,Tao Wang,Xiangyang Liu,Maogang He
New experimental densities and viscosities data for binary mixtures of methyl decanoate plus n -heptane were reported at temperatures of (298.15, 308.15 and 318.15) K and pressures of (0.1–15) MPa. The expanded uncertainty for density measurement is estimated to be 2 kg m −3 and the relative expanded uncertainty for viscosity measurement is estimated to be 0.03. A fitting equation was proposed to correlate the density of the binary mixture and Grunberg-Nissan equation was used to predict the viscosity of the binary mixture, respectively. The maximum absolute relative deviations between the experimental results and calculation values for densities and viscosities were 0.11% and 5.94%, respectively.
研究领域:
化学工程
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物理化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2021
·
IF 3.178
Yuqi Su,Taotao Zhan,Xiangyang Liu,Maogang He,Ying Zhang
The mutual diffusion coefficients of (isooctane + n-heptane) and (n-decane + n-heptane) binary solutions were measured over the mass fraction from 0.05 to 0.95 at the pressure of 0.101 MPa, and at temperatures T = 288.15 K, 298.15 K, 308.15 K and 318.15 K, respectively. The expanded relative uncertainty of the digital holographic interferometry employed in this measurement was estimated to be 2.6% with the confidence level of 0.95 ( k = 2). The influences of temperature and composition on the mutual diffusion coefficients were discussed. Moreover, the semi-empirical correlations of mutual diffusion coefficients for (isooctane + n-heptane) and (n-decane + n-heptane) binary mixtures were given by fitting the experimental results as a function of temperature and mass fraction. The absolute average of relative deviations of the correlations are 0.72% for (isooctane + n-heptane) and 0.54% for (n-decane + n-heptane), respectively.
研究领域:
化学
·
物理化学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF CHEMICAL KINETICS
·
2020
·Vol. 53
·期 3
·428-439
·
IF 1.531
Handong Liao,Haodong Chen,Zhongkai Liu,Ruzheng Zhang,Feng Zhang,Bin Yang
Nonequilibrium plasma has a great potential in the lean combustion of gasoline engines. However, fundamental studies on plasma-assisted combustion on gasoline components are limited. In the present study, Low-temperature oxidation behaviors for n -heptane and iso-octane in a plasma flow reactor were investigated. Species measurements were performed at room temperature and low pressure of 40 mbar using the electron ionization molecular-beam mass spectrometry (EI-MBMS). A total of 72 and 57 species were quantified in n -heptane and iso-octane oxidation, respectively. Based on measured species data, reaction networks of n -heptane and iso-octane in the plasma system were discussed. Particularly, some typical low-temperature intermediates, such as cyclic ethers, diones, and ketohydroperoxides, were observed, suggesting the applicability of the classical low-temperature reaction scheme in the plasma system of large hydrocarbons. The results indicate that the major role of plasma discharge on the low-temperature oxidation of large hydrocarbons is either to breakdown large fuel molecules or to accelerate the chain initiation reactions. We also investigated the parametric effects of voltage, frequency, and residence time on the species pools, and found that the increase of these parameters leads to higher production of intermediates. The whole system reactivity was most sensitive to the plasma voltage. The difference between plasma frequency and residence time on the species formation was found. Moreover, some highly temperature-sensitive reactions, such as the RO 2 → QOOH, proceed at very low temperatures (around 340 K) in the plasma system, which was potentially attributed to the additional energy from plasma-generated species.
研究领域:
化学动力学
·
燃烧学
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2023
·
IF 4.4
Yitong Zhai,Qiang Xu,Beibei Feng,Can Shao,Zhandong Wang,S. Mani Sarathy
Low-temperature (low-T) oxidation experiments of n -heptane –with and without NO addition– were experimentally and numerically investigated at stoichiometric conditions in a jet-stirred reactor. Experiments were performed at atmospheric pressure over a temperature range of 500–800 K. Reactants, intermediates, and products, were measured using synchrotron vacuum ultraviolet photoionization mass spectrometry . A detailed kinetic model was developed to gain insight into the chemical effect of NO on low-T oxidation chemistry of n -heptane. Taking 650 K as the transition temperature, the results revealed that NO addition exhibited an inhibiting effect on fuel reactivity below 650 K and a promoting effect above 650 K. The reactions of ROO + NO = RO + NO 2 and HO 2 + NO = OH + NO 2 at different temperature regions were responsible for the inhibition and promotion effects, respectively. Evidence gathered from both experimental measurements and kinetic model predictions indicated that NO addition had a significant inhibitory effect on the formation of cool flame species during the low-T oxidation process. NO suppressed low-T oxidation via the reaction of ROO + NO = RO + NO 2 , which impeded the subsequent isomerization, O 2 addition, OH-, and HO 2 -elimination reaction, and influenced product distribution of the cool flame species. The experimental observations provided detailed information about these reactive intermediates, which offered new insights into low-T oxidation phenomena and clarified the importance of NO reactions which prevent the formation of cool flame products during low-T oxidation.
研究领域:
化学动力学
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燃烧科学
✓ 已验证
产品关联
DOI
高影响因子
FLUID PHASE EQUILIBRIA
·
2020
·
IF 2.838
Junwei Cui,Shaomin Yan,Jiangtao Wu,Shengshan Bi
In this work, thermal and mutual diffusivity of n -heptane ( n -C 7 H 16 ) with dissolved carbon dioxide (CO 2 ) were simultaneously measured using dynamic light scattering (DLS) method from 298 to 473 K and saturation pressure up to 5.5 MPa. For this purpose, the DLS setup as well as temperature and pressure system were improved. Two hydrodynamic modes in connection with the statistical fluctuations of entropy and species were verified. The average expanded uncertainty of thermal and mutual diffusivity were 9.0% and 4.9% with a coverage factor of k = 2. The thermal and mutual diffusivity versus pressure under isothermal lines were briefly discussed and a comparison with literature was performed. The experimental thermal and mutual diffusivity measured in this work are in reasonable agreement with the literature data. This work is expected to provide fundamental data for engineering process .
研究领域:
化学工程
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2017
·
IF 2.323
Midong Shi,Gaoyin He,Fan Gan,Xuemin Yu,Qingsong Li
In order to reduce the energy consumption of distillation and decomposition of methylal in water, the experimental liquid–liquid equilibria (LLE) data of water + methylal + cyclohexane and water + methylal + n-heptane systems were measured in this work at different temperatures: 303.15 and 313.15 K under atmospheric pressure. The reliability of the tie-line data obtained by this present work was determined using the Othmer–Tobias and Hand equations. Moreover, the LLE data were correlated by nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) models with good results in both systems.
研究领域:
化学工程
·
分离技术
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）