Article
Chemistry, Analytical
Mohammad Nahid Siddiqui, Halim Hamid Redhwi, Dimitris S. Achilias
Summary: In this study, the thermal degradation of polymers is simulated using the random chain-scission model. By combining experiments and mathematical models, kinetic parameters with physical meaning are obtained for comparing the thermal stability of different polymers. The research shows that the dominant degradation mechanism for several polymers in the range of 30% to 90% relative degree of degradation is random scission.
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
(2022)
Article
Engineering, Chemical
Jorge Lopez-Beceiro, Ana Maria Diaz-Diaz, Ana alvarez-Garcia, Javier Tarrio-Saavedra, Salvador Naya, Ramon Artiaga
Summary: A kinetic model was proposed to fit isothermal thermogravimetric data of cellulose at different temperatures in an inert atmosphere. The method involves fitting single time-derivative thermogravimetric curves and rate parameter values obtained at different temperatures separately, demonstrating its flexibility and effectiveness in fitting studies.
Article
Thermodynamics
Laipeng Luo, Zhiyi Zhang, Chong Li, Nishu, Fang He, Xingguang Zhang, Junmeng Cai
Summary: In analyzing kinetic reactions of solid-state reactions like lignocellulosic biomass pyrolysis, the accuracy of determining the kinetic mechanism function using the master plots method depends strongly on the variation degree of the frequency factor with conversion and the conversion dependency of activation energy. Failure to consider these factors when utilizing the master plots method may lead to misestimating the kinetic mechanism function.
Article
Engineering, Chemical
Jiang Wang, Tian -Tian Wang, Zheng-Hong Luo, Yin-Ning Zhou
Summary: In the field of polymer reaction engineering, a sectional strategy based on the method of moments with a newly defined critical chain length was proposed to simulate the degradation process of linear polymers. The model accurately simulates the evolution of average properties and concentration of polymer species during linear polymer degradation, as well as the molar mass distribution. Sensitivity analysis revealed that the rate coefficients of random scission and chain-end scission processes can tune the monomer yields and molecular properties.
CHEMICAL ENGINEERING SCIENCE
(2023)
Article
Chemistry, Analytical
Estefania Orrego-Restrepo, Javier Ordonez-Loza, Farid Chejne
Summary: This study proposes an in situ methodology based on infrared absorption spectra to evaluate the kinetics of cellulose pyrolysis and compare it with existing kinetic models.
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
(2022)
Article
Engineering, Environmental
Weike Liu, Xiaoyuan Zheng, Zhi Ying, Yuheng Feng, Bo Wang, Binlin Dou
Summary: Hydrothermal treatment improves the dewaterability and thermal stability of sewage sludge during pyrolysis. It significantly affects the devolatilization peaks, activation energy, and comprehensive pyrolysis index. The study provides guidance for the design and optimization of pyrolysis reactors when sewage sludge is used as renewable fuels.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2022)
Article
Materials Science, Paper & Wood
Yujin Hwang, Hae-Jun Park, Antje Potthast, Myung-Joon Jeong
Summary: The study revealed that electron beam irradiation significantly affects the chemical and optical properties of paper, but does not adversely affect its physical properties. Proper doses of irradiation can be used for paper disinfection, however, irradiation diminishes paper permanence.
Article
Chemistry, Analytical
Francisco Torres-Herrador, Andreas Eschenbacher, Julien Blondeau, Thierry E. Magin, Kevin M. Van Geem
Summary: Analyzing the thermal degradation data of resin used in manufacturing space debris re-entry objects, it was found that epoxy resin rapidly decomposes at temperatures of 300-400 degrees Celsius. A one-step kinetic model for epoxy pyrolysis based on thermogravimetry observations was proposed for more accurate material degradation models.
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
(2022)
Article
Green & Sustainable Science & Technology
Praveen Kumar Reddy Annapureddy, Nanda Kishore
Summary: Non-isothermal thermogravimetric experiments were conducted to investigate the thermal decomposition of Polyalthia longifolia leaves. The study aimed to determine kinetic triplets and thermodynamic parameters. Five iso-conversional methods were used for kinetic analysis. The results showed that the average activation energy ranged between 211.57 and 231 kJ/mol. The pyrolysis of P. longifolia biomass for bioenergy production was found to be feasible.
JOURNAL OF RENEWABLE AND SUSTAINABLE ENERGY
(2023)
Article
Green & Sustainable Science & Technology
Gozde Gozke
Summary: Converting watermelon seeds into biomass energy is an environmentally friendly opportunity to meet energy demand and reduce reliance on fossil fuels. This study investigated the thermogravimetric pyrolysis of watermelon seeds and determined the pyrolysis characteristics and activation energies. Thermodynamic parameters were also calculated.
Article
Polymer Science
Whitney C. Blocher McTigue, Charles E. Sing
Summary: This paper investigates the degradation process of polymers that can undergo controlled or triggered depolymerization, with a focus on surface-driven polymer scission and the competing unzipping process in self-immolative polymers. The authors develop theoretical models and simulations to study the relationship between depolymerization kinetics and polymer chain conformation under different conditions, providing general predictions.
Article
Polymer Science
Bojan Jankovic, Nebojsa Manic
Summary: The pyrolysis of Wang resin was studied using dynamic simultaneous thermogravimetric analysis and derivative thermogravimetry techniques. A new experimental model was developed to describe the pyrolysis process of the resin, which was divided into three parallel reaction steps using a deconvolution procedure. The mechanistic nature of each step was explained by applying kinetic models.
Article
Agricultural Engineering
Xiaobing Cao, Jie Zhang, Kehui Cen, Fan Chen, Dengyu Chen, Yanjun Li
Summary: Torrefaction pretreatment can effectively reduce the oxygen content in biomass and enhance the carbon content and higher heating value of cellulose. Among the different pretreatment severities studied, treatment at 290°C was found to be the most effective in removing oxygen and improving the properties of cellulose.
BIOMASS & BIOENERGY
(2021)
Article
Chemistry, Applied
Yunhao Liang, Michael E. Ries, Peter J. Hine
Summary: The pyrolysis kinetics of cellulosic fibres, specifically a natural cotton yarn (NCY) and a mercerized cotton yarn (MCY), were investigated using a modified first order global analysis method (FOG) and thermogravimetric analysis (TGA). The results showed that the intrinsic pyrolysis activation energy of NCY and MCY was independent of heating rate and approximation used, with average values of 153 +/- 2 kJ/mol and 192 +/- 7 kJ/mol, respectively. The difference in chemical composition and crystalline structure were hypothesized to be the reasons for the different values. This study provides a new approach for studying the pyrolysis kinetics of biomass and factors influencing their pyrolytic behavior.
CARBOHYDRATE POLYMERS
(2023)
Article
Engineering, Environmental
Huidong Liu, Guoren Xu, Guibai Li
Summary: The pyrolysis kinetics of municipal sludge and pharmaceutical sludge were studied using thermogravimetry, revealing different activation energies and mechanisms. The thermal decomposition was divided into three stages, with different models better explaining the pyrolysis mechanism for each type of sludge. The study also showed that organic matter in sewage sludge can be decomposed into bio-oil and bio-gas at elevated temperatures, making it a promising energy source.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2021)
Article
Chemistry, Multidisciplinary
Juan Jesus Arcenegui Troya, Virginia Moreno, Pedro E. Sanchez-Jimenez, Antonio Perejon, Jose Manuel Valverde, Luis A. Perez-Maqueda
Summary: This study investigates the impact of steam addition during carbonation on the multicyclic performance of limestone under calcium looping conditions. The study finds that steam is beneficial for multicyclic behavior under the milder conditions required for CO2 capture, but its effect is neutral under the more aggressive conditions required for thermochemical energy storage.
ACS SUSTAINABLE CHEMISTRY & ENGINEERING
(2022)
Article
Energy & Fuels
Nabil Amghar, Carlos Ortiz, Antonio Perejon, Jose Manuel Valverde, Luis Perez Maqueda, Pedro E. Sanchez Jimenez
Summary: Thermochemical energy storage (TCES) is a promising storage technology with high energy densities, seasonal storage capacity, and high efficiency. This study investigates the potential of an ultra-high temperature TCES system based on the SrCO3/SrO system and explores the use of refractory additives to enhance the system's multicycle performance. Although current commercial CSP plants cannot yet operate at these ultra-high temperatures, advances in high-temperature solar receivers could enable this in the future.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Materials Science, Ceramics
Sandra Molina-Molina, Antonio Perejon, Luis A. Perez-Maqueda, Pedro E. Sanchez-Jimenez
Summary: This study aims to clarify the influence of AC (up to 50 kHz) vs DC fields on the flash-onset temperature, with a focus on the role of the electrical conduction mechanism. BiFeO3 (BFO) and 8-mol % Yttria-stabilized zirconia (8YSZ) are used as examples of electronic and ionic conductors respectively. The flash-onset temperature and flash-induced heating in 8YSZ exhibit frequency dependence, consistent with different contributions found in the electrical response. Estimations based on the blackbody radiation model suggest that 8YSZ samples achieve higher temperatures under AC fields due to more efficient heating. The decrease in activation energy for electrical conduction after the flash in 8YSZ is attributed to electronic conduction. On the other hand, BFO shows no frequency response and insensitivity to the type of electrical field, indicating mainly electronic bulk conduction.
CERAMICS INTERNATIONAL
(2023)
Article
Thermodynamics
Juan Arcenegui-Troya, Pedro Enrique Sanchez-Jimenez, Antonio Perejon, Luis Allan Perez-Maqueda
Summary: The kinetic analysis of solid-state processes is important for predicting the time evolution of a process under different conditions. Determining kinetic parameters is strongly influenced by the choice of kinetic model. This study shows that the activation energy determined from isothermal curves is independent of the kinetic model used, and proposes a new method for determining activation energy.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
Article
Chemistry, Physical
Alejandro F. Manchon-Gordon, Pedro E. Sanchez-Jimenez, Javier S. Blazquez, Antonio Perejon, Luis A. Perez-Maqueda
Summary: LaFeO3 perovskite ceramics were prepared via reaction flash technique using Fe2O3 and La2O3 precursors. The samples were investigated using various techniques. X-ray diffraction confirmed the formation of LaFeO3. Scanning electron microscopy showed the microporous nature of the samples due to the low temperature and dwell time during synthesis. Differential thermal analysis revealed the orthorhombic-rhombohedral phase transition and the determination of the Neel temperature. Mossbauer spectra confirmed the presence of Fe+3 ions in the tetrahedral site. Magnetic measurements indicated the antiferromagnetic character of the sample at room temperature.
Article
Chemistry, Physical
Alejandro Fernando Manchon-Gordon, Antonio Perejon, Eva Gil-Gonzalez, Maciej Kowalczyk, Pedro E. Sanchez-Jimenez, Luis A. Perez-Maqueda
Summary: The low temperature magnetic properties of BiFeO3 powders sintered by flash and spark plasma sintering were investigated. A phase transition was clearly observed at 250 K through magnetic measurements. The transformation became less well-defined as the grain sizes decreased to nanometer scale, which was attributed to magneto-elastic coupling. The samples exhibited enhanced ferromagnetic properties compared to those prepared using conventional solid-state technique, showing higher coercivity field and remnant magnetization values. The exchange bias effect was more pronounced for the specimen sintered by flash sintering, indicating a stronger exchange interaction between ferromagnetic and antiferromagnetic grains.
Article
Chemistry, Physical
Juan Arcenegui-Troya, Antonio Perejon, Pedro E. Sanchez-Jimenez, Luis A. Perez-Maqueda
Summary: Kinetic analysis is a powerful tool for studying various reactions in material science and industry. However, it often relies on idealized mathematical models that may not match real processes. This study presents a novel method for analyzing integral data without assuming a specific kinetic model. The method uses a general kinetic equation and numerical integration to find the functional form of the kinetic model, making it applicable to both ideal and non-ideal kinetic processes.
Article
Energy & Fuels
Nabil Amghar, Antonio Perejon, Carlos Ortiz, Luis A. Perez Maqueda, Pedro E. Sanchez-Jimenez
Summary: Long-term storage capability is an advantage of the calcium looping process. Experimental results show that storing solids at low temperatures does not substantially affect the multicycle performance, while storing them at high temperatures leads to easier heat integration, better plant efficiency, and higher energy density.
Article
Materials Science, Ceramics
Syed I. A. Jalali, Alejandro F. Manchon-Gordon, Ricardo Chacartegui, Pedro E. Sanchez-Jimenez, Javier S. Blazquez, Antonio Perejon, Rishi Raj, Luis A. Perez-Maqueda
Summary: This work presents an extension of the touch-free flash sintering technique, where chemical reaction and sintering occur simultaneously in the presence of electric and magnetic fields, without the use of electrodes. The study demonstrates the production of a dense, single-phase strontium hexaferrite magnet from a mixture of commercial carbonate and oxide powders in just over a minute. This technique offers significant reductions in energy and time consumption compared to conventional sintering, primarily due to its ultrafast processing.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2023)
Article
Energy & Fuels
Nabil Amghar, Pedro E. Sanchez Jimenez, Luis A. Perez Maqueda, Antonio Perejon
Summary: The multicycle performance of CaO-based materials derived from calcium magnesium acetates with different Mg content in calcium looping was tested under experimental conditions compatible with thermochemical energy storage. Calcination at low CO2 pressure and carbonation at standard pressure resulted in high cycling stability and effective conversion of CaO nanoparticles, leading to significant energy storage density.
JOURNAL OF ENERGY STORAGE
(2023)
Article
Engineering, Environmental
Mehri Imani, Maryam Tahmasebpoor, Pedro Enrique Sanchez-Jimenez
Summary: This study investigates the improvement of adsorption performance of eggshell particles by adding metal nitrates through successive incipient wetness impregnation method. The results show that the smaller the crystal size and the larger the surface area of the modified eggshell particles, the higher the molar conversion of CaO. Among the metal nitrates studied, Mg-containing sample with 5 wt% MgO shows the most outstanding performance in terms of molar conversion, capture capacity, and BET surface area.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2023)
