Thermochimica Acta最新文献

英文中文

Investigation on the effect of carbon powder structural characteristics derived from ethylene decomposition on powder explosion 乙烯分解产生的碳粉结构特征对粉末爆炸影响的研究

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-11-02 DOI: 10.1016/j.tca.2024.179895

Yao Chen , Zhichen Zhang , Yunfeng Zhu , Yahui Li , Shoutao Ma , Haowen Chen , Jie Jiang , Bing Sun , Wei Xu

In LDPE production, ethylene underwent polymerization under high temperature and pressure. However, the heat generated during polymerization could cause ethylene pyrolysis, leading to safety risks. More critically, the carbon powder produced could further decompose, posing additional hazards. This study examined the pyrolysis characteristics of high-pressure, high-temperature ethylene and the explosive behavior of the resulting carbon powder. The decomposition of ethylene was carried out under 80–200 °C and 80–200 MPa with the oxygen concentration of 1000–5000 ppm using ethylene explosive device, and the explosive testing of derived carbon powder was carried out in a 20 L sphere chamber under the powder concentration of 200 g/m³. It was found that higher initial ignition pressure, temperature, and oxygen concentration intensified ethylene pyrolysis. The size of resulting carbon powder ranged from 0.5 to 500 μm and fewer structural defects, leading to stronger explosive intensity due to a larger specific surface area and longer suspension time in the air. Conversely, carbon powder with larger particle sizes and more defects tended to agglomerate, reducing suspension time and explosion intensity. This research provided a theoretical foundation for understanding powder explosions caused by ethylene decomposition.

在低密度聚乙烯生产过程中，乙烯在高温高压下进行聚合。然而，聚合过程中产生的热量会导致乙烯热解，从而引发安全风险。更重要的是，产生的碳粉可能会进一步分解，带来更多危险。本研究考察了高压高温乙烯的热解特性以及由此产生的碳粉的爆炸行为。使用乙烯爆炸装置在 80-200 ℃、80-200 MPa、氧气浓度为 1000-5000 ppm 的条件下对乙烯进行了分解，并在粉末浓度为 200 g/m3 的 20 L 球形室内对衍生碳粉进行了爆炸试验。结果发现，较高的初始点火压力、温度和氧气浓度会加剧乙烯热解。生成的碳粉粒度在 0.5 至 500 μm 之间，结构缺陷较少，由于比表面积较大，在空气中的悬浮时间较长，因此爆炸强度较强。相反，粒度较大、缺陷较多的碳粉往往会结块，从而缩短悬浮时间，降低爆炸强度。这项研究为理解乙烯分解引起的粉末爆炸提供了理论基础。

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引用次数: 0

Characterization of thermal behavior of two types of kaolin in China by ultrafast Joule heating combined with XRD, FT-IR, TG-DSC and SEM 利用超快焦耳加热结合 XRD、FT-IR、TG-DSC 和 SEM 对中国两种高岭土的热行为进行表征

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-11-02 DOI: 10.1016/j.tca.2024.179894

Jiahang Fan, Xianjie Liu, Mingyong Liu, Mengyao Yang, Yuena Jiang, Ruiyu Mi, Xin Min, Zhaohui Huang

Thermal behavior of sandy kaolin selected from Guangxi and hard kaolin from Inner Mongolia in China were characterised by ultrafast Joule heating combined with XRD, FT-IR, TG-DSC and SEM. The results indicated that the sandy kaolin was composed of kaolinite, muscovite and quartz, and hard kaolin was predominantly composed of kaolinite, with minor quantities of anatase. During ultrafast Joule heating, the layered structure of kaolinite of sand kaolin was destroyed, and all hydroxyl groups were lost at 700 °C, while dehydroxylation completion of the hard kaolin at higher temperature, accompanied by rupture of lamellar kaolinite. Muscovite disappeared completely and accompanied by the formation of mullite at 1100 °C, while quartz is relatively unaffected, resulting in the sandy kaolin consisting of quartz and mullite phases at 1200 °C. In contrast, the transformation rate and crystallinity of mullite phase of hard kaolin was significantly higher than that of sandy kaolin.

通过超快焦耳加热并结合 XRD、FT-IR、TG-DSC 和 SEM，对选自中国广西的砂质高岭土和内蒙古的硬质高岭土的热行为进行了表征。结果表明，砂质高岭土由高岭石、黝帘石和石英组成，硬质高岭土主要由高岭石组成，并含有少量锐钛矿。在超快焦耳加热过程中，砂质高岭土高岭石的层状结构遭到破坏，在 700 ℃ 时羟基全部丧失，而硬质高岭土在更高温度下脱羟基完成，并伴随着片状高岭石的破裂。在 1100 ℃ 时，绿泥石完全消失，并伴随着莫来石的形成，而石英则相对不受影响，在 1200 ℃ 时形成了由石英和莫来石相组成的砂质高岭土。相比之下，硬质高岭土莫来石相的转化率和结晶度明显高于砂质高岭土。

引用次数: 0

Extending the Transient Plane Source Scanning method for determining the specific heat capacity of low thermal conductivity materials through a numerical study 通过数值研究扩展用于确定低导热材料比热容的瞬态平面源扫描方法

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-10-28 DOI: 10.1016/j.tca.2024.179883

Zijin Zeng , Christian Müller , Besira Mihiretie

In contrast to the conventional Transient Plane Source (TPS) method, the Transient Plane Source Scanning (TPSS) technique allows for the direct determination of the specific heat capacity and requires the use of a specially designed sample holder for accurate measurements. While this method correctly determines the specific heat capacity of samples with moderate and high thermal conductivity, it tends to underestimate the values for those with low thermal conductivity. This paper demonstrates that the underestimated specific heat capacity results from heat loss during the measurement process. To precisely quantify the heat loss, a numerical model based on the finite element method was developed, with key material properties tuned based on measurement data. This model can closely describe the curve of measured thermal response, thereby enabling the precise determination of the specific heat capacity. Consequently, this study introduces a novel approach that incorporates numerical simulation to enhance TPSS measurements of poorly conducting samples, providing a reliable alternative for determining the specific heat capacity.

与传统的瞬态平面源 (TPS) 方法不同，瞬态平面源扫描 (TPSS) 技术可直接测定比热容，但需要使用专门设计的样品支架才能进行精确测量。虽然这种方法能正确测定中等和高导热系数样品的比热容，但往往会低估低导热系数样品的比热容值。本文证明，比热容被低估的原因是测量过程中的热量损失。为了精确量化热损失，我们根据测量数据调整了关键材料属性，并基于有限元法建立了一个数值模型。该模型可密切描述测量的热响应曲线，从而精确测定比热容。因此，本研究引入了一种新方法，结合数值模拟来增强导电性差样品的 TPSS 测量，为确定比热容提供了一种可靠的替代方法。

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引用次数: 0

Determination of the apparent activation energy surface from isothermal data of char combustion and gasification 根据炭燃烧和气化的等温数据确定表观活化能面

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-10-26 DOI: 10.1016/j.tca.2024.179892

Yongmyong Ri , Tokhui Ri , Hochol Rim , Hyonung Rim , Juhyon Yu , Yongho Kim , Jinhyok Ri

In this paper, the apparent activation energy (AAE) surface was determined by using isothermal data of char combustion and gasification and the apparent Arrhenius equations where the activation parameters depended on temperature and conversion. The dependence of the logarithm of the reaction rate on temperature and conversion was described by the empirical polynomial to increase the accuracy of fitting and the AAE was calculated by the isoconversional method and the fitting of reaction rate and conversion. The AAE surfaces determined for the four examples of char combustion and gasification varied considerably and differently from each other with temperature and conversion. This provides new information for a better understanding of these processes and their kinetic models.

本文利用木炭燃烧和气化的等温数据和表观阿伦尼乌斯方程确定了表观活化能（AAE）面，其中活化参数取决于温度和转化率。为了提高拟合的准确性，用经验多项式描述了反应速率对数与温度和转化率的关系，并通过等转化法和反应速率与转化率的拟合计算了 AAE。在四个炭燃烧和气化实例中测定的 AAE 面随温度和转化率的变化而有很大差异，且彼此不同。这为更好地理解这些过程及其动力学模型提供了新的信息。

引用次数: 0

Heat capacities and thermodynamic functions of three 1-benzyl-4-aryl-1H-1,2,3-triazoles in the temperature range of (0 – Tm) K 三种 1-苄基-4-芳基-1H-1,2,3-三唑在 (0 - Tm) K 温度范围内的热容量和热力学函数

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-10-23 DOI: 10.1016/j.tca.2024.179881

Y.N. Yurkshtovich , A.V. Blokhin , A.G. Labetski , D.I. Shiman , A.A. Notfullin , M.I. Yagofarov

In this paper, we present the results of comprehensive thermodynamic study of some functionally substituted triazoles such as 1-benzyl-4-phenyl-1H-1,2,3-triazole, 1-benzyl-4-(m-tolyl)-1H-1,2,3-triazole and 1-benzyl-4-(4‑tert-butylphenyl)-1H-1,2,3-triazole. The temperature dependences of heat capacities of 1-benzyl-4-(m-tolyl)-1H-1,2,3-triazole and 1-benzyl-4-(4‑tert-butylphenyl)-1H-1,2,3-triazole were measured in a wide temperature range of ∼(5 – 370) K using the adiabatic calorimetry. Those of 1-benzyl-4-phenyl-1H-1,2,3-triazole were determined at the range of ∼(5 – 80) K, supplementing the previous measurements at the more elevated temperatures. The melting parameters and thermal stability (melting temperature, enthalpy of fusion, temperature of thermal destruction) of the compounds were determined using the differential scanning calorimetry. Also, the standard thermodynamic functions (absolute entropies, reduced enthalpies and Gibbs energies) were calculated in the temperature range of (0 – T_m) K.

本文介绍了一些功能取代的三唑，如 1-苄基-4-苯基-1H-1,2,3-三唑、1-苄基-4-（间甲苯基）-1H-1,2,3-三唑和 1-苄基-4-（4-叔丁基苯基）-1H-1,2,3-三唑的综合热力学研究结果。采用绝热量热法测量了 1-苄基-4-(间甲苯基)-1H-1,2,3-三唑和 1-苄基-4-(4-叔丁基苯基)-1H-1,2,3-三唑在 ∼(5 - 370) K 宽温度范围内的热容量随温度变化的关系。在 ∼(5 - 80) K 范围内测定了 1-苄基-4-苯基-1H-1,2,3-三唑的热稳定性，补充了之前在较高温度下的测量结果。利用差示扫描量热法测定了化合物的熔化参数和热稳定性（熔化温度、熔焓、热破坏温度）。此外，还计算了 (0 - Tm) K 温度范围内的标准热力学函数（绝对熵、还原焓和吉布斯能）。

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引用次数: 0

Study of Heavy Oil In-situ Combustion with Copper Biocatalysts: Kinetics and Thermodynamic Aspects of High-Temperature Oxidation Reactions 利用铜生物催化剂研究重油原位燃烧：高温氧化反应的动力学和热力学问题

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-10-22 DOI: 10.1016/j.tca.2024.179882

Mohamed-Said Chemam, Younes Djouadi, Chaima Khelkhal, Olga V. Ostolopovskaya, Mohammed Amine Khelkhal, Alexey V. Vakhin

In-situ combustion is considered an efficient thermally enhanced oil recovery method. However, the combustion front stabilization remains a challenge for the scientific community. The present study examines the efficacy of copper tall oil (Cu-TO) and copper sunflower oil (Cu-SFO) on heavy oil high-temperature oxidation reactions, which are believed to solve this challenge. We applied non-isothermal differential scanning calorimetry (DSC) analyses combined with an isoconversional kinetic approach in order to calculate kinetic parameters, thermodynamic functions, and the effective rate constant of these reactions. The obtained results demonstrated that both catalysts are able to reduce the activation energies and shift oxidation regions to lower temperatures, with Cu-SFO showing superior performance. Kinetic predictions further supported these findings and revealed that the selected catalysts contributed significantly to decreasing oxidation times across all conversion ranges. Additionally, thermodynamic analyses indicated that Cu-SFO facilitated a more ordered and energetically favorable oxidation process, as demonstrated by increasingly negative entropy values and consistently lower Gibbs free energy. The research highlights the Cu-SFO catalyst exceptional ability to accelerate the transition from low-temperature to high-temperature oxidation while maintaining high catalytic activity. Taken together all these results, this research work contributes to provide comprehensive insights from the kinetic and thermodynamic analysis that reveal unique catalytic effects and reaction mechanisms, presenting an approach to stabilize combustion front and improve heavy oil recovery efficiency, addressing a critical challenge in the field of in-situ combustion.

原地燃烧被认为是一种高效的热力强化采油方法。然而，燃烧前沿的稳定仍然是科学界面临的一项挑战。本研究探讨了铜妥尔油（Cu-TO）和铜葵花籽油（Cu-SFO）对重油高温氧化反应的功效，相信它们能解决这一难题。我们采用非等温差示扫描量热法（DSC）分析，结合等转化动力学方法，计算了这些反应的动力学参数、热力学函数和有效速率常数。结果表明，这两种催化剂都能降低活化能，并将氧化区转移到较低的温度，其中 Cu-SFO 的性能更优。动力学预测进一步支持了这些发现，并表明所选催化剂在所有转化范围内都能显著缩短氧化时间。此外，热力学分析表明，Cu-SFO 促进了更有序、能量更有利的氧化过程，这表现在熵值越来越负，吉布斯自由能越来越低。这项研究凸显了 Cu-SFO 催化剂在保持高催化活性的同时加速从低温氧化向高温氧化过渡的卓越能力。综合所有这些结果，这项研究工作有助于从动力学和热力学分析中提供全面的见解，揭示独特的催化效应和反应机理，提出了一种稳定燃烧前沿和提高重油采收效率的方法，解决了原位燃烧领域的一个关键挑战。

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引用次数: 0

Design and implementation of an accelerating rate calorimeter based on Modelica modeling 基于 Modelica 建模的加速热量计的设计与实施

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-10-18 DOI: 10.1016/j.tca.2024.179877

Botao Tang , Tao Zhou , Lei Ni , Liang Yin , Juncheng Jiang , Ahmed Mebarki

The safety of self-reactive chemicals has garnered attention due to their immense destructive power. The use of an accelerating rate calorimeter allows for more accurate measurement and understanding of the kinetic parameters and reaction mechanisms of self-reactive chemicals, thereby reducing the occurrence of major accidents. In this study, a new accelerating rate calorimeter is designed and constructed by combining Modelica and a fuzzy Proportional-Integral-Derivative algorithm. The feasibility of the calorimeter data was verified by using two solutions with significantly different reaction rates: 20 % mass fraction di‑tert‑butyl peroxide/toluene and tert-butylperoxy-2-ethylhecanoate. Their thermal hazard characteristic parameters were compared with the literature data. In addition, the risk level of thermal runaway was determined using the Stoessel risk assessment method. These results demonstrate that the accelerating rate calorimeter based on Modelica modeling meets the accuracy of thermal hazard characteristic parameters. It is capable of performing risk assessments for runaway reactions of self-reactive chemicals.

自反应化学品具有巨大的破坏力，因此其安全性备受关注。使用加速量热仪可以更准确地测量和了解自反应化学品的动力学参数和反应机理，从而减少重大事故的发生。在本研究中，通过结合 Modelica 和模糊比例-积分-求导算法，设计并构建了一种新的加速速率量热仪。通过使用两种反应速率明显不同的解决方案，验证了量热计数据的可行性：质量分数为 20% 的过氧化二叔丁基/甲苯和过氧化叔丁基-2-乙基己酸酯。它们的热危害特征参数与文献数据进行了比较。此外，还采用斯托塞尔风险评估方法确定了热失控的风险等级。这些结果表明，基于 Modelica 建模的加速热量计能够满足热危害特征参数的准确性要求。它能够对自反应化学品的失控反应进行风险评估。

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引用次数: 0

Insights into the thermal stabilization mechanism of zeolitic imidazolate framework-8 for poly(vinyl chloride) 沸石咪唑酸盐框架-8 对聚氯乙烯热稳定机制的启示

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-10-16 DOI: 10.1016/j.tca.2024.179880

Shuhang Li, Xianglin Liao, Zhinan Zhang, Xue Chen, Luobiao Hong, Cong Liu, Suilian Luo, Qiong Hou, Yuhai Wang, Guang Shi

The thermal stability of zeolitic imidazolate framework-8 (ZIF-8) for poly(vinyl chloride) (PVC) has received attention, but its thermal stabilization mechanism needs further clarification. Herein, the stearic acid-modified ZIF-8 with high specific surface area and large pore volume was effectively synthesized by using zinc stearate as the zinc source for the first time. Modification of stearic acid results in larger adsorption capacity of ZIF-8 for HCl and better thermal stability effect for PVC, especially long-term thermal stability. Moreover, the thermal stability mechanism of ZIF-8 for PVC was demonstrated by experiments and theoretical calculations. In addition to absorbing HCl to eliminate autocatalytic degradation of PVC, ZIF-8 disintegrates and may form 2-methylimidazole-Zn-Cl salt complex instead of free ZnCl2, avoiding the negative zinc burning effect. Furthermore, the Diels-Alder reaction between imidazole ring and degraded PVC prevents the extension of the conjugated double bonds of PVC and delays the deepening of the color of PVC.

用于聚氯乙烯（PVC）的沸石咪唑酸框架-8（ZIF-8）的热稳定性已受到关注，但其热稳定性机理有待进一步阐明。本文首次以硬脂酸锌为锌源，有效合成了具有高比表面积和大孔隙率的硬脂酸改性 ZIF-8。硬脂酸的改性使 ZIF-8 对盐酸的吸附容量更大，对 PVC 的热稳定性效果更好，尤其是长期热稳定性。此外，实验和理论计算还证明了 ZIF-8 对 PVC 的热稳定性机理。除了吸收 HCl 以消除 PVC 的自催化降解外，ZIF-8 还会分解并形成 2-甲基咪唑-锌-氯盐络合物，而不是游离的 ZnCl2，从而避免了锌的负燃烧效应。此外，咪唑环与降解聚氯乙烯之间的 Diels-Alder 反应可防止聚氯乙烯共轭双键的延伸，延缓聚氯乙烯颜色的加深。

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引用次数: 0

Thermoluminescence characteristics of UV-irradiated natural hackmanite 紫外线辐照天然黑云母的热致发光特性

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-10-11 DOI: 10.1016/j.tca.2024.179879

Chuchu Song , Qingfeng Guo , Yafang Wang , Libing Liao

Hackmanite has received extensive attention from scholars in recent years. However, there is still no report on the thermoluminescence properties of natural hackmanites under UV irradiation, as well as its relative electron trap and luminescence center. In this paper, the structural defects and thermoluminescence spectroscopic properties of hackmanite are comprehensively characterized by XRD, TL spectroscopy, SEM, EPR, XPS and Raman spectroscopy. The traps depth of TL peaks are calculated by computerized glow curve deconvolution (CGCD) techniques. And the charge transition energy levels of intrinsic defects in Na₈Al₆Si₆O₂₄(Cl,S)₂ are calculated by spin-polarized density-functional theory (DFT) in VASP. It shows that the low-temperature TL peaks of hackmanite are associated with Cl vacancies and photochromic properties. The high-temperature peak is caused by marginal oxygen vacancies. The results are conducive to deepening the understanding of structural defects of the hackmanites and linking the thermoluminescence with the phototropy.

近年来，黑云母受到了学者们的广泛关注。然而，关于天然 hackmanite 在紫外辐照下的热致发光特性，以及其相对电子阱和发光中心的研究，目前还没有相关报道。本文通过 XRD、TL 光谱、扫描电镜、EPR、XPS 和拉曼光谱对黑曼石的结构缺陷和热致发光光谱特性进行了综合表征。利用计算机辉光曲线解卷积（CGCD）技术计算了 TL 峰的阱深度。并在 VASP 中通过自旋极化密度泛函理论（DFT）计算了 Na8Al6Si6O24(Cl,S)2 中固有缺陷的电荷转换能级。结果表明，黑芒硝的低温 TL 峰与 Cl 空位和光致变色特性有关。高温峰是由边缘氧空位引起的。这些结果有助于加深对黑芒硝结构缺陷的理解，并将热致发光与光致变色联系起来。

引用次数: 0

Thermal properties and decomposition of perovskite energetic materials (C6H14N2) NH4 (ClO4)3 过氧化物高能材料 (C6H14N2) NH4 (ClO4)3 的热性能和分解过程

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL

Thermochimica Acta

Pub Date : 2024-10-11 DOI: 10.1016/j.tca.2024.179878

Xiaohong Wang , Juan Zhao , Xiaoyu Li , Qing Pan , Langhua Gao , Gao Zhang

(C₆N₂H₁₄) NH₄ (ClO₄)₃ (DAP-4) have attracted an increasing focus recently as an ammoniumperchlorate-based molecular perovskite energetic material with outstanding features. Microscopy, variable temperature X-ray diffraction, in situ infrared spectroscopy, differential scanning calorimetry-thermogravimetry simultaneous thermal analysis coupled with infrared spectroscopy and mass spectrometry (DSC-TG/FTIR/MS) techniques were used to systematically investigate DAP-4 thermal properties from -40 °C to 550 °C. The results revealed that DAP-4 have two solid-solid crystallization phase transitions with a non-characteristic melting process. The generated activation energies of HCN, CO, CH₂NH₂, CO₂ and NO₂ gas products are all lower than the macroscopic decomposition's of DAP-4. This finding strongly proves that DAP-4 is easy to form these gas products during thermal stimulus. The two stages decomposition mechanism accompanying a large of CH₂NH₂ and NH₂C₂H₄ gases and kinetic model of DAP-4 were proposed under the condition of high-purity argon gas. This study provides new insight into the in-depth and accurate description thermal decomposition mechanism of DAP-4 as a potential energetic material.

(C6N2H14) NH4 (ClO4)3 (DAP-4)作为一种以高氯酸铵为基础的分子包光体高能材料，其卓越的特性最近引起了越来越多的关注。本研究采用显微镜、变温 X 射线衍射、原位红外光谱、差示扫描量热法-热重法同时热分析耦合红外光谱和质谱（DSC-TG/FTIR/MS）技术，系统研究了 DAP-4 从 -40 ℃ 到 550 ℃ 的热性能。结果表明，DAP-4 有两个固-固结晶相变，熔化过程不具特征性。生成的 HCN、CO、CH2NH2、CO2 和 NO2 气体产物的活化能均低于 DAP-4 的宏观分解能。这一发现有力地证明了 DAP-4 在热刺激过程中很容易形成这些气体产物。在高纯度氩气条件下，提出了伴随大量 CH2NH2 和 NH2C2H4 气体的两阶段分解机理以及 DAP-4 的动力学模型。这项研究为深入准确地描述作为潜在高能材料的 DAP-4 的热分解机理提供了新的视角。

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