scholarly journals Non-isothermal reaction mechanism and kinetic analysis for the synthesis of monoclinic lithium zirconate (m-Li2ZrO3) during solid-state reaction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Juan P. Yasnó ◽  
Susana Conconi ◽  
Arnaldo Visintin ◽  
Gustavo Suárez
Keyword(s):  
Reaction Mechanism ◽  
Solid State ◽  
Kinetic Analysis ◽  
Solid State Reaction ◽  
Diffusion Mechanism ◽  
Model Fitting ◽  
Isoconversional Methods ◽  
Heating Rates ◽  
Isothermal Reaction ◽  
Lithium Zirconate

AbstractNon-isothermal reaction mechanism and kinetic analysis for the synthesis of monoclinic lithium zirconate (m-Li2ZrO3) were investigated by processing of TG-DTA, along with XRD, DLS, and HRTEM. For this purpose, the solid-state reaction of Li2CO3 with ZrO2 was carried out by TG-DTA at different heating rates (10, 20, and 30 °C/min) from room temperature to 1100 °C. The thermal data was used to calculate the kinetic parameters by two types of isoconversional methods: Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS). The reaction mechanism was determined by the model-fitting method, applying the Coats-Redfern (CR) approximation to the different solid-state reaction models. The results confirmed the formation of pure m-Li2ZrO3, consists of semispherical particles of about 490 nm, using a very short reaction time. The average activation energy obtained by FWO and KAS methods were 274.73 and 272.50 kJ/mol, respectively. It was found that the formation of m-Li2ZrO3 from Li2CO3 with ZrO2 is governed by the three-dimensional diffusion mechanism. Based on these results, a microscopic reaction model of the formation of m-Li2ZrO3 was proposed.

Reaction Mechanism and Kinetic Analysis of the Decomposition of Phosphogypsum via a Solid-State Reaction

2010 ◽  
Vol 49 (8) ◽  
pp. 3597-3602 ◽  
Author(s):  
Liping Ma ◽  
Ping Ning ◽  
Shaocong Zheng ◽  
Xuekui Niu ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Solid State ◽  
Kinetic Analysis ◽  
Solid State Reaction

Study of the reaction mechanism between electroless Ni–P and Sn and its effect on the crystallization of Ni–P

2003 ◽  
Vol 18 (1) ◽  
pp. 4-7 ◽  
Author(s):  
Y. C. Sohn ◽  
Jin Yu ◽  
S. K. Kang ◽  
W. K. Choi ◽  
D. Y. Shih
Keyword(s):  
Reaction Mechanism ◽  
Solid State ◽  
Solid State Reaction ◽  
Crystallization Temperature ◽  
Low Temperatures ◽  
Transformation Temperature ◽  
The Self ◽  
Heat Of Reaction ◽  
Solder Reaction ◽  
Electroless Ni

The reaction mechanism between electroless Ni–P and Sn was investigated to understand the effects of Sn on solder reaction-assisted crystallization at low temperatures as well as self-crystallization of Ni–P at high temperatures. Ni3Sn4 starts to form in a solid-state reaction well before Sn melts. Heat of reaction for Ni3Sn4 was measured during the Ni–P and Sn reaction (241.2 J/g). It was found that the solder reaction not only promotes crystallization at low temperatures by forming Ni3P in the P-rich layer but also facilitates self-crystallization of Ni–P by reducing the transformation temperature and heat of crystallization. The presence of Sn reduces the self-crystallization temperature of Ni–P by about 10 °C. The heat of crystallization also decreases with an increased Sn thickness.

scholarly journals Pyrolysis Kinetic Properties of Thermal Insulation Waste Extruded Polystyrene by Multiple Thermal Analysis Methods

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5595
Author(s):  
Ang Li ◽  
Wenlong Zhang ◽  
Juan Zhang ◽  
Yanming Ding ◽  
Ru Zhou
Keyword(s):  
Reaction Mechanism ◽  
Thermal Insulation ◽  
Conversion Rate ◽  
Model Fitting ◽  
Pso Algorithm ◽  
Energy Utilization ◽  
Kinetic Properties ◽  
Insulation Material ◽  
Heating Rates ◽  
Model Free

Extruded polystyrene (XPS) is a thermal insulation material extensively applied in building systems. It has attracted much attention because of outstanding thermal insulation performance, obvious flammability shortcoming and potential energy utilization. To establish the reaction mechanism of XPS’s pyrolysis, thermogravimetric experiments were performed at different heating rates in nitrogen, and multiple methods were employed to analyze the major kinetics of pyrolysis. More accurate kinetic parameters of XPS were estimated by four common model-free methods. Then, three model-fitting methods (including the Coats-Redfern, the iterative procedure and masterplots method) were used to establish the kinetic model. Since the kinetic models established by the above three model-fitting methods were not completely consistent based on different approximations, considering the effect of different approximates on the model, the reaction mechanism was further established by comparing the conversion rate based on the model-fitting methods corresponding to the possible reaction mechanisms. Finally, the accuracy of the above model-fitting methods and Particle Swarm Optimization (PSO) algorithm were compared. Results showed that the reaction function g(α) = (1 − α)−1 − 1 might be the most suitable to characterize the pyrolysis of XPS. The conversion rate calculated by masterplots and PSO methods could provide the best agreement with the experimental data.

scholarly journals Kinetic Analysis of the Thermal Degradation of Recycled Acrylonitrile-Butadiene-Styrene by non-Isothermal Thermogravimetry

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 281 ◽  
Author(s):  
Rafael Balart ◽  
David Garcia-Sanoguera ◽  
Luis Quiles-Carrillo ◽  
Nestor Montanes ◽  
Sergio Torres-Giner
Keyword(s):  
Thermal Degradation ◽  
Kinetic Analysis ◽  
Acrylonitrile Butadiene Styrene ◽  
Isoconversional Methods ◽  
Reaction Model ◽  
Integral Model ◽  
Heating Rates ◽  
Exponential Factor ◽  
Model Free ◽  
Butadiene Styrene

This work presents an in-depth kinetic study of the thermal degradation of recycled acrylonitrile-butadiene-styrene (ABS) polymer. Non-isothermal thermogravimetric analysis (TGA) data in nitrogen atmosphere at different heating rates comprised between 2 and 30 K min−1 were used to obtain the apparent activation energy (Ea) of the thermal degradation process of ABS by isoconversional (differential and integral) model-free methods. Among others, the differential Friedman method was used. Regarding integral methods, several methods with different approximations of the temperature integral were used, which gave different accuracies in Ea. In particular, the Flynn-Wall-Ozawa (FWO), the Kissinger-Akahira-Sunose (KAS), and the Starink methods were used. The results obtained by these methods were compared to the Kissinger method based on peak temperature (Tm) measurements at the maximum degradation rate. Combined Kinetic Analysis (CKA) was also carried out by using a modified expression derived from the general Sestak-Berggren equation with excellent results compared with the previous methods. Isoconversional methods revealed negligible variation of Ea with the conversion. Furthermore, the reaction model was assessed by calculating the characteristic and functions and comparing them with some master plots, resulting in a nth order reaction model with n = 1.4950, which allowed calculating the pre-exponential factor (A) of the Arrhenius constant. The results showed that Ea of the thermal degradation of ABS was 163.3 kJ mol−1, while ln A was 27.5410 (A in min−1). The predicted values obtained by integration of the general kinetic expression with the calculated kinetic triplet were in full agreement with the experimental data, thus giving evidence of the accuracy of the obtained kinetic parameters.

scholarly journals Kinetic studies on the pyrolysis of plastic waste using a combination of model-fitting and model-free methods

2020 ◽  
Vol 38 (1_suppl) ◽  
pp. 77-85 ◽  
Author(s):  
Zhitong Yao ◽  
Shaoqi Yu ◽  
Weiping Su ◽  
Weihong Wu ◽  
Junhong Tang ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Thermogravimetric Analysis ◽  
Compensation Effect ◽  
Model Fitting ◽  
Plastic Waste ◽  
Plastic Shell ◽  
Ozawa Method ◽  
Heating Rates ◽  
Helium Atmosphere ◽  
Model Free

In this work, the pyrolysis behavior of plastic waste—TV plastic shell—was investigated, based on thermogravimetric analysis and using a combination of model-fitting and model-free methods. The possible reaction mechanism and kinetic compensation effects were also examined. Thermogravimetric analysis indicated that the decomposition of plastic waste in a helium atmosphere can be divided into three stages: the minor loss stage (20–300°C), the major loss stage (300–500°C) and the stable loss stage (500–1000°C). The corresponding weight loss at three different heating rates of 15, 25 and 35 K/min were determined to be 2.80–3.02%, 94.45–95.11% and 0.04–0.16%, respectively. The activation energy ( Ea) and correlation coefficient ( R2) profiles revealed that the kinetic parameters calculated using the Friedman and Kissinger–Akahira–Sunose method displayed a similar trend. The values from the Flynn–Wall–Ozawa and Starink methods were comparable, although the former gave higher R2 values. The Eα values gradually decreased from 269.75 kJ/mol to 184.18 kJ/mol as the degree of conversion ( α) increased from 0.1 to 0.8. Beyond this range, the Eα slightly increased to 211.31 kJ/mol. The model-fitting method of Coats–Redfern was used to predict the possible reaction mechanism, for which the first-order model resulted in higher R2 values than and comparable Eα values to those obtained from the Flynn–Wall–Ozawa method. The pre-exponential factors (ln A) were calculated based on the F1 reaction model and the Flynn–Wall–Ozawa method, and fell in the range 59.34–48.05. The study of the kinetic compensation effect confirmed that a compensation effect existed between Ea and ln A during the plastic waste pyrolysis.

The growth of silica and silica-clad nanowires using a solid-state reaction mechanism on Ti, Ni and SiO2layers

2010 ◽  
Vol 21 (29) ◽  
pp. 295603 ◽  
Author(s):  
Parul Sharma ◽  
J V Anguita ◽  
V Stolojan ◽  
S J Henley ◽  
S R P Silva
Keyword(s):  
Reaction Mechanism ◽  
Solid State ◽  
Solid State Reaction

Solid-State Reaction Mechanism and Deliquescence Phenomenon of K0.5Na0.5Nb0.7Al0.3O3 Ceramic

2017 ◽  
Vol 46 (10) ◽  
pp. 5563-5569 ◽  
Author(s):  
Lu Gao ◽  
Wancheng Zhou ◽  
Fa Luo ◽  
Dongmei Zhu
Keyword(s):  
Reaction Mechanism ◽  
Solid State ◽  
Solid State Reaction
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