The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Mengjia Huo - One of the best experts on this subject based on the ideXlab platform.
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transesterification catalyzed by industrial waste lime mud doped with potassium fluoride and the Kinetic Calculation
Energy Conversion and Management, 2014Co-Authors: Shengli Niu, Mengqi Liu, Mengjia HuoAbstract:Abstract Lime mud (LM), a solid waste from paper mill, is doped with potassium fluoride to prepare heterogeneous base transesterification catalyst. The catalyst is characterized by Hammett indicator method, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The experimental results show that the basic strength of catalyst is the main reason for high catalytic activity. After doped with 20 wt.% KF and activated at 600 °C (KF/LM-600), the effects of catalyst addition percentage, molar ratio of methanol to oil, transesterification time, and transesterification temperature are concerned to examine the catalytic activity of KF/LM-600 and the reusability of KF/LM-600 is also investigated. Oil conversion of 99.09% could be achieved with catalyst addition percentage 5 wt.%, molar ratio of methanol to oil 12, transesterification time 2 h and transesterification temperature 64 °C. Furthermore, the Kinetic parameters of transesterification catalyzed by KF/LM-600 are calculated.
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Transesterification catalyzed by industrial waste—Lime mud doped with potassium fluoride and the Kinetic Calculation
Energy Conversion and Management, 2014Co-Authors: Shengli Niu, Mengqi Liu, Mengjia HuoAbstract:Abstract Lime mud (LM), a solid waste from paper mill, is doped with potassium fluoride to prepare heterogeneous base transesterification catalyst. The catalyst is characterized by Hammett indicator method, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The experimental results show that the basic strength of catalyst is the main reason for high catalytic activity. After doped with 20 wt.% KF and activated at 600 °C (KF/LM-600), the effects of catalyst addition percentage, molar ratio of methanol to oil, transesterification time, and transesterification temperature are concerned to examine the catalytic activity of KF/LM-600 and the reusability of KF/LM-600 is also investigated. Oil conversion of 99.09% could be achieved with catalyst addition percentage 5 wt.%, molar ratio of methanol to oil 12, transesterification time 2 h and transesterification temperature 64 °C. Furthermore, the Kinetic parameters of transesterification catalyzed by KF/LM-600 are calculated.
Shengli Niu - One of the best experts on this subject based on the ideXlab platform.
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Thermal Characteristics and Kinetic Calculation of Castor Oil Pyrolysis
Procedia Engineering, 2017Co-Authors: Shengli NiuAbstract:Abstract To investigate the thermal characteristics of castor oil pyrolysis, the fatty acid composition was firstly analyzed via gas chromatograph (GC). Then, the thermal characteristics was evaluated through the thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) under nitrogen atmosphere at 5, 10, 15, and 20 K min-1 from 298.2 K to 873.2 K. Based on the iso-conversional method, pyrolysis Kinetic parameter of the activation energy was calculated by the free model approaches of Kissinger-Akahira-Sunose method (KAS) and Flynn-Wall-Ozawa method (FWO). In addition, the reaction order was calculated through Avrami theory. The average activation energy values were calculated as 202.88 kJ mol-1 and 203.66 kJ mol-1 for KAS method and FWO method, respectively. And the average value of reaction order is 1.02.
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an investigation on the catalytic capability of the modified white mud after activation in transesterification and Kinetic Calculation
Energy, 2015Co-Authors: Shengli Niu, Yan Zhou, Li LiuAbstract:Abstract White mud is modified by acetic acid and then activated at 700 °C to catalyze transesterification. After modification and activation, the prepared catalyst (labeled as MWM–700 ) mainly consists of calcium oxide with a surface area of 7.97 m 2 g −1 and basic strength of 9.8 H_ MWM–700 catalyzed transesterification of peanut oil with methanol supplies an efficiency of 97.43%. With the seventh time usage, a catalytic efficiency of 89.33% is still supplied. Meanwhile, the repeated experiments are conducted to confirm the reproducibility and reliability of the experimental results. The chemical structure and physical properties of the produced biodiesel are detected, which are in accordance with ASTM D 6751. Finally, the Kinetic parameters of the MWM–700 catalyzed transesterification are calculated, where the activation energy is 66.82 kJ mol −1 and the pre-exponential factor is 1.36 × 10 9 min −1 .
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An investigation on the catalytic capability of the modified white mud after activation in transesterification and Kinetic Calculation
Energy, 2015Co-Authors: Shengli Niu, Yan Zhou, Li LiuAbstract:White mud is modified by acetic acid and then activated at 700 °C to catalyze transesterification. After modification and activation, the prepared catalyst (labeled as MWM–700) mainly consists of calcium oxide with a surface area of 7.97 m2 g−1 and basic strength of 9.8 < H_ < 15.0. Under the optimized condition of the catalyst added amount of 6 wt%, molar ratio of methanol to oil of 15, reaction temperature of 64 °C and reaction time of 150 min, the MWM–700 catalyzed transesterification of peanut oil with methanol supplies an efficiency of 97.43%. With the seventh time usage, a catalytic efficiency of 89.33% is still supplied. Meanwhile, the repeated experiments are conducted to confirm the reproducibility and reliability of the experimental results. The chemical structure and physical properties of the produced biodiesel are detected, which are in accordance with ASTM D 6751. Finally, the Kinetic parameters of the MWM–700 catalyzed transesterification are calculated, where the activation energy is 66.82 kJ mol−1 and the pre-exponential factor is 1.36 × 109 min−1.
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transesterification catalyzed by industrial waste lime mud doped with potassium fluoride and the Kinetic Calculation
Energy Conversion and Management, 2014Co-Authors: Shengli Niu, Mengqi Liu, Mengjia HuoAbstract:Abstract Lime mud (LM), a solid waste from paper mill, is doped with potassium fluoride to prepare heterogeneous base transesterification catalyst. The catalyst is characterized by Hammett indicator method, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The experimental results show that the basic strength of catalyst is the main reason for high catalytic activity. After doped with 20 wt.% KF and activated at 600 °C (KF/LM-600), the effects of catalyst addition percentage, molar ratio of methanol to oil, transesterification time, and transesterification temperature are concerned to examine the catalytic activity of KF/LM-600 and the reusability of KF/LM-600 is also investigated. Oil conversion of 99.09% could be achieved with catalyst addition percentage 5 wt.%, molar ratio of methanol to oil 12, transesterification time 2 h and transesterification temperature 64 °C. Furthermore, the Kinetic parameters of transesterification catalyzed by KF/LM-600 are calculated.
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Transesterification catalyzed by industrial waste—Lime mud doped with potassium fluoride and the Kinetic Calculation
Energy Conversion and Management, 2014Co-Authors: Shengli Niu, Mengqi Liu, Mengjia HuoAbstract:Abstract Lime mud (LM), a solid waste from paper mill, is doped with potassium fluoride to prepare heterogeneous base transesterification catalyst. The catalyst is characterized by Hammett indicator method, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The experimental results show that the basic strength of catalyst is the main reason for high catalytic activity. After doped with 20 wt.% KF and activated at 600 °C (KF/LM-600), the effects of catalyst addition percentage, molar ratio of methanol to oil, transesterification time, and transesterification temperature are concerned to examine the catalytic activity of KF/LM-600 and the reusability of KF/LM-600 is also investigated. Oil conversion of 99.09% could be achieved with catalyst addition percentage 5 wt.%, molar ratio of methanol to oil 12, transesterification time 2 h and transesterification temperature 64 °C. Furthermore, the Kinetic parameters of transesterification catalyzed by KF/LM-600 are calculated.
Nobuyoshi Koga - One of the best experts on this subject based on the ideXlab platform.
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Critical Appraisal of Kinetic Calculation Methods Applied to Overlapping Multistep Reactions.
Molecules (Basel Switzerland), 2019Co-Authors: Nikita V. Muravyev, Alla N. Pivkina, Nobuyoshi KogaAbstract:Thermal decomposition of solids often includes simultaneous occurrence of the overlapping processes with unequal contributions in a specific physical quantity variation during the overall reaction (e.g., the opposite effects of decomposition and evaporation on the caloric signal). Kinetic analysis for such reactions is not a straightforward, while the applicability of common Kinetic Calculation methods to the particular complex processes has to be justified. This study focused on the critical analysis of the available Kinetic Calculation methods applied to the mathematically simulated thermogravimetry (TG) and differential scanning calorimetry (DSC) data. Comparing the calculated Kinetic parameters with true Kinetic parameters (used to simulate the thermoanalytical curves), some caveats in the application of the Kissinger, isoconversional Friedman, Vyazovkin and Flynn–Wall–Ozawa methods, mathematical and Kinetic deconvolution approaches and formal Kinetic description were highlighted. The model-fitting approach using simultaneously TG and DSC data was found to be the most useful for the complex processes assumed in the study.
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Physico-geometric Kinetics of complex solid-state reactions
2018Co-Authors: Nobuyoshi Koga, L. A. Pérez-maqueda, Loïc Favergeon, N. V. Muravyev, S. YamadaAbstract:Kinetic analysis of the solid-state reaction using thermal analysis (TA) is the established scientific tool and widely applied to many technological processes. However, many solid-state reactions proceed with complex behavior regulated by heterogeneous characteristics. Rather simple solid-state reactions should be described by considering consecutive physico-geometrical processes such as surface reaction–reaction interface shrinkage and nucleation–growth. Further, the surface product layer produced by the reaction regulates diffusion of gases that contribute to the reaction as reactant and product. The mass transfer phenomena influence on the rate behavior and sometimes impede the reaction. Formation of diffusion path in the surface product layer is necessary for the reactivation. As the result, the overall reaction proceeds as the multistep reaction caused by the physico-geometrical constraints. The concurrent or consecutive chemical reactions occurring in the solid-state exhibit more complex Kinetic behavior. For these reactions, the comparing reaction steps can indicate differently signed TA signals, i.e., mass loss versus mass gain and exothermic versus endothermic effects. For extending basic Kinetic theory and the Kinetic Calculation methods using TA data to be applicable to the complex solid-state reactions, detailed case studies for the selected reaction processes that exhibit different physico-chemical and physico-geometrical complexities are necessary. In this presentation, the cutting-edge of the Kinetic analysis for the complex solid-state reactions is briefly reviewed with special attentions to (i) Kinetic deconvolution analysis, (ii) induction period–surface reaction–phase boundary controlled reaction model, and (iii) impact of the evolved gas on the overall Kinetics.
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Logic and strategy for the Kinetic analysis of complex solid-state reactions
2017Co-Authors: Nobuyoshi Koga, L. A. Pérez-maqueda, Loïc Favergeon, N. V. Muravyev, S. YamadaAbstract:Kinetic description of the complex solid-state reactions is a challenging task, because of the overall process compraizing different heterogeneous reaction steps occuring concecutively or concurrently. For extending basic Kinetic theory and the Kinetic Calculation methods using thermoanalytical data established for the single-step reaction to be applicable to the complex solid-state reactions, detailed case studies for the selected reaction processes with different physico-chemical and physico-geometrical complexities are neccessary. In this presentation, the cutting-edge of the Kinetic analysis for the complex solid-state reactions are briefly reviewed and the strategy for contributing toward the provision of theoretical foundation of the Kinetic analysis for the complex solid-state reactions are discussed with a special attention to the role of the Kinetic deconvolution analysis.
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A review of the mutual dependence of Arrhenius parameters evaluated by the thermoanalytical study of solid-state reactions: the Kinetic compensation effect
Thermochimica Acta, 1994Co-Authors: Nobuyoshi KogaAbstract:Abstract The Kinetic compensation effect (KCE) has been observed in numerous Kinetic studies of solid-state reactions using thermoanalytical methods. An attempt has been made to separate phenomenologically the KCE into the variation and the mutual dependence of the resultant Arrhenius parameters. The probability of the mutual dependence of the Arrhenius parameters caused by the properties of the general Kinetic equation was discussed in relation to: (1) the reaction temperature interval, (2) the fractional reaction α, (3) the Kinetic model function f (αf), and (4) the isoKinetic hypothesis. The mutual dependence of the Arrhenius parameters due to the properties of the general Kinetic equation was first checked before discussing the KCE in relation to a physico-chemical factor for a series of reactions under investigation. The necessity of establishing a check system for the Kinetic Calculation is discussed briefly on the basis of the prerequisities of the methods of Kinetic Calculation and the properties of the general Kinetic equation.
M. F. Thomsen - One of the best experts on this subject based on the ideXlab platform.
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Propagation and damping of broadband upstream whistlers
Advances in Space Research, 1995Co-Authors: D. S. Orlowski, Christopher T. Russell, D Krauss-varban, N Omidi, M. F. ThomsenAbstract:Abstract Previous studies indicated that damping rates of upstream whistlers strongly depend on the details of the electron distribution function. Moreover, detailed analysis of Doppler-shift and whistler dispersion relation indicated that upstream whistlers propagate obliquely in a broad band. In this paper we present results of a Kinetic Calculation of damping lengths of wide-band whistlers using the sum of 7-drifting bi-Maxwellian electron distributions as a best fit to the ISEE 1 electron data. For 2 cases, when upstream whistlers are observed, convective damping lengths derived from ISEE magnetic field and ephemeris data are compared with theoretical results. We find that the calculated convective damping lengths are consistent with the data and that upstream whistlers remain marginally stable. We also show that the slope of plasma frame spectra of upstraem whistlers, obtained by direct fitting of the observed spectra is between 5 and 7 with a sharp lower frequency cutoff corresponding to a wavelength of about one ion inertial length. When the solar wind velocity is directed largely along the wave normal of the upstream whistlers the polarization of the right hand waves becomes reversed and low frequencies are switched to high resulting in a peaked spectrum with a strong high frequency cutoff. The overall spectral, wave and particle characteristics, proximity to the shock as well as propagation and damping properties indicate that these waves cannot be generated locally. Instead the observed upstream whistlers arise in the shock ramp most likely by a variety of cross-field drift and/or anisotropy driven instabilities.
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Damping and spectral formation of upstream whistlers
Journal of Geophysical Research, 1995Co-Authors: D. S. Orlowski, Christopher T. Russell, D Krauss-varban, N Omidi, M. F. ThomsenAbstract:Previous studies have indicated that damping rates of upstream whistlers strongly depend on the details of the electron distribution function. Moreover, detailed analysis of Doppler shift and the whistler dispersion relation indicate that upstream whistlers propagate obliquely in a finite band of frequencies. In this paper we present results of a Kinetic Calculation of damping lengths of wideband whistlers using the sum of seven drifting bi-Maxwellian electron distributions as a best fit to the ISEE 1 electron data. For two cases, when upstream whistlers are observed, convective damping lengths derived from ISEE magnetic field and ephemeris data are compared with theoretical results. We find that the calculated convective damping lengths are consistent with the data and that upstream whistlers remain marginally stable. We also show that the slope of plasma frame spectra of upstream whistlers, obtained by direct fitting of the observed spectra, is between 5 and 7. The overall spectral, wave, and particle characteristics, proximity to the shock, as well as propagation and damping properties indicate that these waves cannot be generated locally. Instead, the observed upstream whistlers arise in the shock ramp, most likely by a variety of cross-field drift and/or anisotropy driven instabilities.
Mengqi Liu - One of the best experts on this subject based on the ideXlab platform.
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transesterification catalyzed by industrial waste lime mud doped with potassium fluoride and the Kinetic Calculation
Energy Conversion and Management, 2014Co-Authors: Shengli Niu, Mengqi Liu, Mengjia HuoAbstract:Abstract Lime mud (LM), a solid waste from paper mill, is doped with potassium fluoride to prepare heterogeneous base transesterification catalyst. The catalyst is characterized by Hammett indicator method, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The experimental results show that the basic strength of catalyst is the main reason for high catalytic activity. After doped with 20 wt.% KF and activated at 600 °C (KF/LM-600), the effects of catalyst addition percentage, molar ratio of methanol to oil, transesterification time, and transesterification temperature are concerned to examine the catalytic activity of KF/LM-600 and the reusability of KF/LM-600 is also investigated. Oil conversion of 99.09% could be achieved with catalyst addition percentage 5 wt.%, molar ratio of methanol to oil 12, transesterification time 2 h and transesterification temperature 64 °C. Furthermore, the Kinetic parameters of transesterification catalyzed by KF/LM-600 are calculated.
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Transesterification catalyzed by industrial waste—Lime mud doped with potassium fluoride and the Kinetic Calculation
Energy Conversion and Management, 2014Co-Authors: Shengli Niu, Mengqi Liu, Mengjia HuoAbstract:Abstract Lime mud (LM), a solid waste from paper mill, is doped with potassium fluoride to prepare heterogeneous base transesterification catalyst. The catalyst is characterized by Hammett indicator method, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The experimental results show that the basic strength of catalyst is the main reason for high catalytic activity. After doped with 20 wt.% KF and activated at 600 °C (KF/LM-600), the effects of catalyst addition percentage, molar ratio of methanol to oil, transesterification time, and transesterification temperature are concerned to examine the catalytic activity of KF/LM-600 and the reusability of KF/LM-600 is also investigated. Oil conversion of 99.09% could be achieved with catalyst addition percentage 5 wt.%, molar ratio of methanol to oil 12, transesterification time 2 h and transesterification temperature 64 °C. Furthermore, the Kinetic parameters of transesterification catalyzed by KF/LM-600 are calculated.
