An alternative approach to kinetic analysis of temperature-programmed reaction data

Portnyagin, A. S.; Голиков, А. П.; Дрозд, Владимир; Авраменко, В. А.

doi:10.1039/c7ra09848k

Cited by 11 publications

(6 citation statements)

References 38 publications

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“…The reaction has to consist of a number of reaction steps, and for each of these steps the reaction rate can be described by the kinetic equation 5, depending on the concentration of the initial reactant e j , the concentration of the product p j , the preexponential factor A j and the activation energy E j . This equation is specific for the reaction step j and the reaction type of each step can be described by the function f j [24].

true α = A_{j} f_{j} (() e_{j}, p_{j}) e x p ([], \frac{- E_{j}}{((), R, T)})

…”

Section: Resultsmentioning

confidence: 99%

Kinetic Predictions Concerning the Long‐Term Stability of TKX‐50 and Other Common Explosives Using the NETZSCH Kinetics Neo Software

Harter

Klapötke

Lechner

et al. 2022

Propellants Explo Pyrotec

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Explosives are used in both military and civilian applications all over the world. Sufficient longevity and good thermal stability are therefore essential for safe handling and safe storage of energetic materials. In this work, five well‐known compounds, TKX‐50, RDX, HMX, CL‐20 and PETN, were investigated by means of different kinetic models, in order to make predictions about their long‐term stability. For this purpose, the compounds were synthesized according to literature‐known procedures and thermogravimetric (TG) measurements were performed. The TG plots were analyzed using the Ozawa‐Flynn‐Wall, Friedman and ASTM E698 kinetic models with the NETZSCH Kinetics Neo software and the activation energy and isothermal long‐term stability were determined. Moreover, various climatic predictions of different countries were made.

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true α = A_{j} f_{j} (() e_{j}, p_{j}) e x p ([], \frac{- E_{j}}{((), R, T)})

…”

Section: Resultsmentioning

confidence: 99%

Kinetic Predictions Concerning the Long‐Term Stability of TKX‐50 and Other Common Explosives Using the NETZSCH Kinetics Neo Software

Harter

Klapötke

Lechner

et al. 2022

Propellants Explo Pyrotec

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show abstract

“…There is no sound theory that enable us to introduce a mathematical expression for the surface area functions a priori, so they are found in the class of cubic splines s i (α i ) [24,25], which provide the controlled precision based on a variable amount of spline knots. Additionally, the absence of theoretical assumptions on the mathematical form of surface area functions enabled us to take into account all the occurring processes throughout the reduction, thus making the approach versatile [26]. Optimized parameters in this case are a vector of values λ i (y i,0 , .…”

Section: Methodsmentioning

confidence: 99%

“…Full mathematical description of the method is given in [26]. Sorption under static conditions was performed as follows.…”

Section: Methodsmentioning

confidence: 99%

Morphological Features and Sorption Performance of Materials Based on Birnessite Exposed to Various Reductive Conditions

Portnyagin

Egorin

Голиков

et al. 2018

Colloids and Interfaces

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The article is devoted to the evolution of structural, morphological, and sorption characteristics of layered manganese oxide (birnessite) under various conditions close to the real operating regime of the sorbents for radioactive waste processing. To identify the phase composition in the birnessites, we implemented XRD analysis, while SEM and temperature-programmed reduction (TPR) were used to study morphological and redox features of the materials, respectively. Structural changes after various kinds of treatment of birnessites were tracked using low temperature nitrogen sorption. Sorption characteristics were assessed under static and in dynamic conditions on the efficiency of Sr2+ removal from simulated seawater. TPR combined with kinetic analysis revealed the decrease of particle sizes in the birnessites after repeated use in sorption-regeneration cycle and reduction with hydrazine. Despite the fact that the porous structure of the materials remains preserved, the surface morphology of birnessite changes drastically depending on the reducing agent. Hydrazine treatment increases the sorption performance of the birnessite followed by degradation of mechanical properties, thus, preventing such sorbent from repeated use. Kinetic analysis of TPR allows quantifying differences in morphology and porous structure of manganese oxide materials. The specific surface area, amorphous surface structure, and accessibility of Mn+3 sites are the most important factors for birnessite sorption performance.

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“…For example, in order to obtain the number of active sites of the catalyst sample, the existing process is based on the proportional relationship between the integral area under the measured TCD curve and the number of sites. Therefore, traditional TPR characterization can only provide some qualitative or semi-quantitative information, such as the ratio of hydrogen consumption in different reduction stages, rather than the exact number of hydrogen molecules consumed. , On the other hand, the TPR reaction of H 2 with the catalyst generates H 2 O molecules, which significantly affects the detection of TCD to hydrogen. − Hence, it is generally necessary to install a cold trap system in the instrument to remove the produced H 2 O molecules from the gas stream prior to the detection. − The use of cold traps brings complexity to the instrument construction and experimental operation and also increases the distance between the detector and the sample, which may lead to weak and delayed ex situ detection signals. Further, some highly active catalysts with ultra-low TPR temperatures have drawn much attention to achieve a green and sustainable development. − However, it is difficult for the existing TPR instruments to initiate TPR measurements from below the freezing point. , Therefore, developing an in situ H 2 -TPR measurement method with high sensitivity and wide operating temperature range is of great significance to meet the requirements of high-performance catalyst characterization.…”

Section: Introductionmentioning

confidence: 99%

In Situ Hydrogen Temperature-Programmed Reduction Technology Based on the Integrated Microcantilever for Metal Oxide Catalyst Analysis

Zhou

et al. 2022

Anal. Chem.

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Hydrogen temperature-programmed reduction (H 2 -TPR) technique is significant for catalyst characterization. The available instruments typically measure the H 2 consumption using a thermal conductivity detector (TCD), which is strongly affected by the produced H 2 O molecules. Herein, we demonstrate an in situ TPR technology based on a silicon microcantilever, in which resonance exciting/detecting components and heating electrodes for catalyst samples are integrated. The microcantilever-based H 2 -TPR technology requires only 20 ng of the sample and eliminates the requirements of TCD and cold trap. During the self-heating up to 1000 °C, reduction-induced mass change of the sample can be in situ measured with picogram-level resolution. Compared with the available instruments, the microcantilever-based H 2 -TPR technology directly and in situ measures the mass change of the sample, without using H 2 consumption to indirectly represent the reduction process, thus significantly improving the characterization accuracy. The microcantilever-based TPR technology has been successfully used to characterize various metal oxide catalysts with satisfactory accuracy. The in situ TPR results of the three CuO samples with different grain sizes clearly distinguish their different maximum temperatures, revealing the size effect of the catalyst. The microcantilever can also be placed in a low-temperature test chamber, enabling successful frozen H 2 -TPR analysis of catalysts with low reduction temperatures, such as PdO. Featuring simplified operation but high detecting accuracy, the microcantilever-based in situ H 2 -TPR technology is promising in the analytic applications of advanced catalysts.

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An alternative approach to kinetic analysis of temperature-programmed reaction data

Abstract: Presented method of kinetic analysis of non-isothermal reaction data provides precise kinetic parameters for different materials with different morphology and particle size.

Cited by 11 publications

References 38 publications

Kinetic Predictions Concerning the Long‐Term Stability of TKX‐50 and Other Common Explosives Using the NETZSCH Kinetics Neo Software

Kinetic Predictions Concerning the Long‐Term Stability of TKX‐50 and Other Common Explosives Using the NETZSCH Kinetics Neo Software

Morphological Features and Sorption Performance of Materials Based on Birnessite Exposed to Various Reductive Conditions

In Situ Hydrogen Temperature-Programmed Reduction Technology Based on the Integrated Microcantilever for Metal Oxide Catalyst Analysis

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