共查询到20条相似文献,搜索用时 140 毫秒
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利用转篮式无梯度反应器,在工业Fe-Mn催化剂上,在较宽的工业操作相关的反应条件下进行了F-T合成反应动力学研究. 首次提出了利用转篮式无梯度反应器反应气氛和反应温度均一的优势,将烃生成反应动力学的估算从传统的对烃生成和水煤气变换这两类发生在不同活性中心的反应同时进行估算的方法中分离出来,简化了烃生成动力学模型的计算. 在基于亚甲基插入的亚烷基机理动力学模型基础上,考虑到乙烯与催化剂表面强的相互作用,将乙烯和乙烷的生成动力学参数单独计算. 动力学模型计算的链增长、烷烃和烯烃生成的活化能均与文献报道值具有较好的一致性. 由F-T合成动力学模型计算的合成气消耗速率、甲烷生成速率和C5+的生成速率较好地与实验值吻合. 通过动力学模型并结合实验结果分析发现,未考虑除化学反应之外的非本征因素的烯烃再吸附动力学模型不能够正确预测烃产物分布偏离ASF规律及烯烷比随碳数增加而下降的现象. 相似文献
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用DSC研究纯三水铝石溶出动力学 总被引:1,自引:0,他引:1
在DSC上研究了NaOH溶液中合成三水铝石的溶出过程动力学。应用非等温反应动力学模型计算了动力学参数,分析和确定了反应机理。模型计算结果与用DSC测得的结果吻合。 相似文献
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基于Monte Carlo模拟的化学反应动力学参数估算 总被引:2,自引:0,他引:2
提出并采用基于MonteCarlo模拟与动力学实验相结合的化学反应动力学参数估算方法,由基元反应确定MonteCarlo模拟具体做法,将MonteCarlo模拟结果与动力学实验结果相比较,根据比较结果自动调整和优化动力学参数,从而无需事先确定动力学方程即可有效估算各种化学反应的动力学参数值.采用该方法估算了丙烯氨氧化反应动力学参数,并对估算结果进行了分析与讨论. 相似文献
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费托合成蜡是费托合成反应中的重要产物之一。采用高温气相色谱与冷柱头进样相结合的方式,建立了一种分离分析费托合成蜡的气相色谱方法。该方法无需对费托合成蜡进行预处理,使用氦气为载气,选用更长的高温色谱柱,具有平稳的色谱基线,对费托合成蜡中正构烷烃和其他未知组分有很好的分离效果,能够洗脱费托合成蜡中碳数大于C90的重组分。用高温气相色谱-质谱法对费托合成蜡馏分进行定性分析,其组分有烷烃、烯烃和含氧化合物。该方法对了解费托合成蜡组分的详细信息和费托合成工艺的开发有重要意义。 相似文献
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Ali Nakhaei Pour Mohammad Reza Housaindokht Sayyed Faramarz Tayyari Jamshid Zarkesh 《天然气化学杂志》2010,19(4):441-445
Kinetic parameters of nano-structured iron catalyst in Fischer-Tropsch synthesis (FTS) were studied in a wide range of synthesis gas conversions and compared with conventional catalyst. The conventional Fe/Cu/La catalyst was prepared by co-precipitation of Fe and Cu nitrates in aqueous media and Fe/Cu/La nanostructure catalyst was prepared by co-precipitation in a water-in-oil micro-emulsion. Nano-structured iron catalyst shows higher FTS activity. Kinetic results indicated that in FTS rate expression, the rate constant (k) increased and adsorption parameter (b) decreased by decreasing the catalyst particle size from conventional to nano-structured. Since increasing in the rate constant and decreasing in the adsorption parameter affected the FTS rate in parallel direction, the particle size of catalyst showed complicated effects on kinetic parameters of FTS reaction. 相似文献
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《Journal of Energy Chemistry》2017,26(3):359-367
The kinetic of the direct CO_2 hydrogenation to higher hydrocarbons via Fischer–Tropsch synthesis(FTS)and reverse water-gas shift reaction(RWGS) mechanisms over a series of precipitated Fe/Cu/K catalysts with various particle sizes was studied in a well mixed, continuous spinning basket reactor. The iron catalysts promoted with copper and potassium were prepared via precipitation technique in various alcohol/water mixtures to achieve a series of catalyst particle sizes between 38 and 14 nm. A new kinetic model for direct CO_2 hydrogenation was developed with combination of kinetic model for FTS reaction and RWGS equilibrium condition. For estimate of structure sensitivity of indirect CO_2 hydrogenation to higher hydrocarbons, the kinetic parameters of developed model are evaluated for a series of iron catalysts with various particle sizes. For kinetic study a wide range of syngas conversions have been obtained by varying experimental conditions. The results show that the new developed model fits favorably with experimental data. The values of activation energies for indirect CO_2 hydrogenation reaction are fall within the narrow range of 23–16 kJ/mol. 相似文献
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BalSang Lee In Hyeok Jang Jong Wook Bae Soong Ho Um Pil J. Yoo Myung-June Park Yong Chul Lee Ki-Won Jun 《Catalysis Surveys from Asia》2012,16(3):121-137
The present paper represents the promising ways to improve catalytic performance by introducing zirconium phosphate (ZP) on Ru/Co/SiO2 catalysts and the related kinetic models using the optimized Fischer?CTropsch synthesis (FTS) catalyst. A lot of works has been reported using cobalt-based catalyst for FTS reaction, and many authors have continuously tried to find out highly efficient FTS catalyst by modifying support as well as by introducing promoters. Silica is one of the excellent candidates as catalytic supports, and the present works intensively represents how to modify SiO2 support for a high catalytic performance by using ZP species. The effect of ZP-modification of SiO2 support with respect to cobalt aggregation and catalytic deactivation was mainly investigated for FTS reaction. The surface modification at P/(Zr?+?P) molar ratio between 0.029 and 0.134, enhanced the spatial confinement effect of cobalt clusters, and resulted in high catalytic stability with the help of well-dispersed ZP particle formation. The enhanced catalytic performance, in terms of CO conversion, C5+ selectivity and catalytic stability, is mainly attributed to the suppressed aggregation, a homogeneous distribution of cobalt clusters with a proper size and a low mobility of cobalt clusters at an optimum molar ratio of P/(Zr?+?P) because of the formation of thermally stable ZP particles. The kinetic parameters and rate equations on the optimized catalyst are also derived in terms of CO conversion and product distribution. 相似文献
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The effect of Co particle size on the Fischer-Tropsch synthesis (FTS) activity of carbon nanotube (CNT)-supported Co catalysts was investigated. Microemulsion (using water-to-surfactant molar ratios of 2 to12) and impregnation techniques were used to prepare catalysts with different Co particle sizes. Kinetic studies were performed to understand the effect of Co particle size on catalytic activity. Size-dependent kinetic parameters were developed using a thermodynamic method, to evaluate the structural sensitivity of the CNT-supported Co catalysts. The size-independent FTS reaction rate constant and size-independent adsorption parameter increased with increasing reac-tion temperature. The Polani parameter also depended on catalyst particle size, because of changes in the catalyst surface coverage. 相似文献
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《催化学报》2015,(8)
The effect of Co particle size on the Fischer-Tropsch synthesis(FTS) activity of carbon nanotube(CNT)-supported Co catalysts was investigated. Microemulsion(using water-to-surfactant molar ratios of 2 to12) and impregnation techniques were used to prepare catalysts with different Co particle sizes. Kinetic studies were performed to understand the effect of Co particle size on catalytic activity. Size-dependent kinetic parameters were developed using a thermodynamic method, to evaluate the structural sensitivity of the CNT-supported Co catalysts. The size-independent FTS reaction rate constant and size-independent adsorption parameter increased with increasing reaction temperature. The Polani parameter also depended on catalyst particle size, because of changes in the catalyst surface coverage. 相似文献
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《国际化学动力学杂志》2017,49(12):859-874
A detailed kinetic model of Fischer–Tropsch synthesis (FTS) product formation, including secondary methane formation and 1‐olefin hydrogenation, has been developed. Methane formation in FTS over the cobalt‐based catalyst is well known to be higher‐than‐expected compared to other n‐paraffin products under typical reaction conditions. A novel model proposes secondary methane formation on a different type of active site, which is not active in forming C2+ products, to explain this anomalous methane behavior. In addition, a model of secondary 1‐olefin hydrogenation has also been developed. Secondary 1‐olefin hydrogenation is related to secondary methane formation with both reactions happening on the same type of active sites. The model parameters were estimated from experimental data obtained with Co/Re/γ‐Al2O3 catalyst in a slurry‐phase stirred tank reactor over a range of conditions (T = 478, 493, and 503 K, P = 1.5 and 2.5 MPa, H2/CO feed ratio = 1.4 and 2.1, and X CO = 16–62%). The proposed model including secondary methane formation and 1‐olefin hydrogenation is shown to provide an improved quantitative and qualitative prediction of experimentally observed behavior compared to the detailed model with only primary reactions. 相似文献
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Ali Nakhaei Pour Mohammad Reza Housaindokht Farshad Torabi 《Journal of the Iranian Chemical Society》2014,11(6):1639-1648
The kinetic parameters of water–gas shift (WGS) reaction in the Fischer–Tropsch synthesis (FTS) on lanthanum-promoted iron catalyst are analyzed by size-dependent thermodynamic method. A Langmuir–Hinshelwood kinetic equation is considered for the catalysts activity evaluation. A series of unsupported iron catalysts with different particle sizes are prepared via microemulsion method. These results show that the iron particle size has considerable effects on reactants adsorption and WGS kinetic parameters and WGS activity pass from a maximum by increasing the catalyst particle size. Finally, the analysis of data showed that by increasing the iron particle from 14 to 41 nm, the WGS activation energies and heats of adsorption of carbon monoxide and water on catalysts increased from 68 to 83, 22 to 28 and 75 to 94 kJ/mol, respectively. 相似文献
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引言化学露光计是用来测定光强的光化学反应体系,一种好的露光计在一定的波长下,其量子产率是完全确定的。本文应用已知的草酸铁钾露光计标定光强,藉以测定偶氮苯光异构化反应的量子产率。早在1957年Zimmerman等人首次提出偶氮苯可以作为露光计,继而,在1976年Gauglitz 用动力学方法直接测得其量子产率。我们的工作是在吸收了Gauglitz方法优点的基础上,对偶氮苯光异构化反应量子产率的测定方法加以改进,将计算机的作用从简单计算扩大到对动力学经验方程的拟合,从而简化了实验操作,并能获得比较 相似文献
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Analysis of related time-resolved fluorescence measurements can possibly lead to the determination of the kinetic parameters of excited-state processes. A deterministic identifiability analysis on an error-free fluorescence decay data surface has to be executed to verify whether the parameters of a particular model can be determined and may point to the minimal experimental conditions under which this will become possible. In this work, similarity transformation is chosen as an identifiability analysis approach because it also gives the explicit relationships between the true and alternative model parameters. Results are presented for two kinetic models of a reversible intermolecular two-state excited-state process in isotropic environments: (a) with coupled species-dependent rotational diffusion described by Brownian reorientation and (b) with added quencher. For model a, both spherically and cylindrically symmetric rotors, with no change in the principal axes of rotation in the latter, are considered. The fluorescence delta-response functions I(parallel)(t) and I(perpendicular)(t), for fluorescence polarized respectively parallel and perpendicular to the electric vector of linearly polarized excitation, are used to define the sum S(t) = I( parallel)(t) + 2 I( perpendicular)(t) and the difference D(t) = I(parallel)(t) - I(perpendicular)(t) function. The identifiability analysis is carried out using the S(t) and D(t) functions. The analysis involving S(t) shows that two physically acceptable possible solutions for the overall rate constants of the excited-state process exist. Inclusion of information from polarized fluorescence measurements on the rotational kinetic behavior contained in D(t) results in the unique set of rate constants and rotational diffusion coefficients when the rotational diffusion coefficients are different. For model b, it is shown that addition of quencher plays formally the same role as rotational diffusion as far as the identification is concerned. When the quenching rate constants are different, the rate constants of a reversible intermolecular two-state excited-state process with added quencher can be uniquely determined. 相似文献
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Shang-Hao Liu Chun-Ping Lin Chi-Min Shu 《Journal of Thermal Analysis and Calorimetry》2011,106(1):165-172
The thermokinetic parameters were investigated for cumene hydroperoxide (CHP), di-tert-butyl peroxide (DTBP), and tert-butyl
peroxybenzoate (TBPB) by non-isothermal kinetic model and isothermal kinetic model by differential scanning calorimetry (DSC)
and thermal activity monitor III (TAM III), respectively. The objective was to investigate the activation energy (E
a) of CHP, DTBP, and TBPB applied non-isothermal well-known kinetic equation to evaluate the thermokinetic parameters by DSC.
We employed TAM III to assess the thermokinetic parameters of three liquid organic peroxides, obtained thermal runaway data,
and then used the Arrhenius plot to obtain the E
a of liquid organic peroxides at various isothermal temperatures. In contrast, the results of non-isothermal kinetic algorithm
and isothermal kinetic algorithm were acquired from a highly accurate procedure for receiving information on thermal decomposition
characteristics and reaction hazard. 相似文献