Kissinger Akahira Sunose Research Articles

The significant role of passive oxide layer on reactive metal combustion: insights into composite solid propellant with superior performance

ABSTRACT Passive oxide layer could expose a significant impact on reactive metal combustion. Boron and aluminum experience combustion enthalpy of 59.3 and 31.1 KJ/g and passive oxide layer of 200 and 7 nm, respectively. In this study, surface oxygen of born and aluminum particles (10 µm) was quantified via EDAX analysis. Boron and aluminum demonstrated surface oxygen content of 14.6 and 7.2 wt %, respectively. Reactive particles were integrated into ammonium perchlorate (AP) oxidizer. While boron demonstrated decrease in AP decomposition enthalpy by −14.8%; aluminum offered an increase in AP decomposition enthalpy by 60.8% using DSC. Whereas, aluminum oxide layer could be pealed out more effectively; boron passive oxide layer could melt with the evolution of an insulating barrier. Aluminum particles offered decrease in AP apparent activation energy by 68%, 105%, and 76% using Kissinger, Kissinger-Akahira-Sunose (KAS), and Flyn and Wall (FWO) models, respectively. Solid propellant formulations were developed; ballistic performance was assessed using small-scale rocket motor. Aluminum particles demonstrated stable combustion process with enhanced specific impulse and total pressure impulse compared with boron. Additionally, aluminum particles demonstrated stable burning with pressure exponent of 0.19 compared with 0.4 for boron particles.

Degradation kinetics of PLA compounds with castor oil

AbstractPoly (lactic acid) (PLA) compounds with castor oil (CO) and epoxidized castor oil (ECO) were produced via formic acid, with levels of 5% CO, 3 and 5% ECO. The contribution of this study lies in the detailed analysis of thermal degradation and degradation kinetics of PLA/CO and PLA/ECO. Chemical changes were evidenced by Fourier transform infrared (FTIR), thermal stability, and degradation kinetics were investigated by thermogravimetric analysis (TGA), using Friedman (FR), Ozawa–Flynn–Wall (OFW), Kissinger–Akahira–Sunose (KAS) and Vyazovkin (VZ) models. Results showed changes in FTIR spectra for PLA/CO and PLA/ECO. For PLA/5%CO and PLA/3%ECO, lower energy bonds formation were observed, resulting in modifications in the involved molecules and presence of CH type bonds in PLA/5%ECO. TGA analysis showed that PLA presented greater thermal stability compared with PLA/CO and PLA/ECO, with T5% = 306°C. The compounds 5% CO, 3 and 5% ECO exhibited lower degradation temperatures (298, 300, and 296°C), compared with PLA, as well as slower decomposition rates. Kinetic modeling using KAS and OFW models proved to be incapable of describing the degradation kinetics of PLA and its compounds. However, FR and VZ were considered adequate, with discrepancies varying between 7% to −4% and 9% to −3%, which showed higher (215, 185, 210, 189 KJ/mol) at α = 0.3 for PLA.

Synthesis and characterization of statistical and block copolymers of n‐hexyl isocyanate and 2‐chloroethyl isocyanate via coordination polymerization

AbstractStatistical and block copolymers of n‐hexyl isocyanate (HIC) and 2‐chloroethyl isocyanate (ClEtIC) were synthesized via cοοrdination polymerization employing the half‐titanocene complex [(η5‐C5H5)((S)‐2‐Bu‐O)TiCl2] as initiator. The complex, bearing a chiral substituent, led to optically active products, as confirmed by circular dichroism measurements. The molecular characterization of all products was carried out by NMR and IR spectroscopy and size exclusion chromatography (SEC), while their thermal stability was investigated through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and differential thermogravimetry (DTG). The reactivity ratios of the two monomers were determined using various graphical methods, as well as the COPOINT program, according to the terminal copolymerization model. Structural parameters, such as the dyad monomer sequences and the mean sequence lengths were calculated as well. In addition, the kinetics of the thermal degradation of the statistical copolymers was studied, and the activation energies of the thermal degradation were calculated employing the Kissinger, Ozawa–Flynn–Wall (OFW), and Kissinger–Akahira–Sunose (KAS) methods. The block copolymers were synthesized by sequential addition of monomers starting from the polymerization of HIC. Well‐defined products were obtained in a controlled way as revealed by SEC, IR, and NMR measurements.

Multi-objective genetic algorithm approach for enhanced cumulative hydrogen and methane-rich syngas emission through co-pyrolysis of de-oiled microalgae and coal blending

Towards establishing low-carbon bio-economy, the energy-rich syngas is considered a global energy carrier. Targeting hydrogen as a promising advanced fuel, the significance of methane also increases due to its direct conversion capability into hydrogen. The current study aims to use a co-pyrolysis-based valorization of de-oiled microalgae and low-rank coal blend to generate H2 and CH4 rich syngas. Pyrolysis kinetic models, Kissinger-Akahira-Sunose (KAS) and Starink (STK) are used to evaluate apparent activation energy (Ea). The gradual addition of microalgae (0⎼100%) in coal reduces Ea from 189.11⎼55.87 kJ/mol and 180.16⎼54.61 kJ/mol by KAS and STK method, respectively. The maximum hymethane carrying ratio is observed 2.51 and 3.51 at optimized conditions of response surface methodology (RSM) and artificial neural network-based multi-objective genetic algorithm (ANN-MOGA), respectively. Maximum H2 (54.5 %) in the syngas is observed at mid pyrolysis stage (451 °C) using ANN-MOGA optimized conditions (blending ratio - 42.25 % and heating rate-13.8 °C/min). This study highlights the advantage of ANN-MOGA optimization over statistical based optimization. Hence, incorporating of the evolutionary algorithm as integrated ANN-MOGA optimization could be an efficient way for hymethane rich syngas emission in co-pyrolysis approach to gain carbon-neutral energy with zero waste discharge.

Curing and degradation kinetics of crosslinked epoxidized soybean oil with isosorbide-based curing agent

This work explores the synthesis of the isosorbide-based curing agent with methyltetrahydrophthalic anhydride (MTHPA). Synthesized for the first time, the isosorbide methylphthalate acid (IMPA) and its effects on the crosslinking of epoxidized soybean oil (ESO) are investigated. The curing and degradation kinetics of the synthesized compounds were investigated for molar ratios 1:1, 1:0.50 and 1:0.25 for ESO/IMPA and 1:1 ESO/MTHPA. ESO/IMPA 1:0.50 had the lowest cure activation energies during the highest cure conversion range, between 10% and 55%, and the highest degradation activation energies during the 30 and 60% conversion. The Friedman and Vyazovkin isoconversional models provided R2 > 0.99 for cure, except for the ESO/MTHPA composition, presenting a lower R2. In degradation kinetics, the Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) kinetic models presented R2 > 0.99, while the degradation mechanisms were adequately adjusted with Avrami-Erofeev (An) and autocatalytic (n,m)th order (Cnm) during the first and second degradation step. Microstructural analyzes and deeper investigations into the degradation mechanisms in the solid state indicated that in the ESO/IMPA and ESO/MTHPA compounds the processes are controlled by diffusion.

Study on the Influence of Porous Gel on Coal Pyrolysis Performance Based on Experiments and Molecular Simulation

ABSTRACT Studying the kinetics of pyrolysis in pure coals and mixed coals (coals treated with porous gel) holds immense significance in effectively preventing and controlling the spontaneous combustion occurrences in coal. Firstly, porous gel materials were prepared based on physical mixing and chemical crosslinking reaction. Then, based on the thermogravimetric analysis method, the pyrolysis mechanism of porous gel in coal was studied using Flynn-Wall-Ozawa(FWO), Kissinger-Akahira-Sunose(KAS) and Coats Redfern models. Determine the mechanism of coal pyrolysis reaction using the Reaxx FF MD reaction mechanics model. Finally, the inhibition mechanism of porous gel on coal is analyzed through leading temperature rise experiment. The main reaction mechanisms of coal pyrolysis are the diffusion model in the low-conversion-rate range (D4), the R2 and R3 in the high-conversion-rate range, and the Avrami erofeev model (A2, A3). The molecular simulation results indicate that increasing the heating rate can accelerate the rate of coke cracking.

Kinetics Study of PVA Polymer by Model-Free and Model-Fitting Methods Using TGA.

Thermogravimetric Analysis (TGA) serves a pivotal technique for evaluating the thermal behavior of Polyvinyl alcohol (PVA), a polymer extensively utilized in the production of fibers, films, and membranes. This paper targets the kinetics of PVA thermal degradation using high three heating rate range 20, 30, and 40 K min-1. The kinetic study was performed using six model-free methods: Freidman (FR), Flynn-Wall-Qzawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink (STK), Kissinger (K), and Vyazovkin (VY) for the determination of the activation energy (Ea). TGA showed two reaction stages: the main one at 550-750 K and the second with 700-810 K. But only the first step has been considered in calculating Ea. The average activation energy values for the conversion range (0.1-0.7) are between minimum 104 kJ mol-1 by VY to maximum 199 kJ mol-1 by FR. Model-fitting has been applied by combing Coats-Redfern (CR) with the master plot (Criado's) to identify the most convenient reaction mechanism. Ea values gained by the above six models were very similar with the average value of (126 kJ mol-1) by CR. The reaction order models-Second order (F2) was recommended as the best mechanism reaction for PVA pyrolysis. Mechanisms were confirmed by the compensation effect. Finally, (∆H, ∆G, and ∆S) parameters were presented and proved that the reaction is endothermic.

Hydrothermal carbonization of corncob for hydrochar production and its combustion reactivity in a blast furnace.

A key factor restricting the application of biochar in the steel industry is its high-quality upgrading. This paper evaluated the characteristics of hydrochar produced by HTC (hydrothermal carbonization) process of corncob to be used as a solid fuel. HTC temperatures (240-300°C) and HTC water-reused times (1-3 times) were examined for their effects on hydrochar yield, physicochemical characteristics, and combustion properties. The results showed hydrochar yields, O/C, and H/C parameters decreased as HTC temperature and water-reused times increased, while its high heating value increased. Due to dehydration and decarboxylation, hydrochar showed similar characteristics to those in bituminous coal. The removal efficiency of alkali metal K reached 99% after HTC treatment. Carbonaceous hydrochar had become more compact, orderly, and stable with increasing amounts of aromatic functional groups, C = C, and C = O. Hydrochar, as a biofuel, has higher ignition energy and is more stable than corncob due to its high carbonaceous order degree. To calculate combustion kinetic parameters, the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods were applied. The results revealed that Eα (average activation energy) was quite similar between the two models. HC-300 had an Eα of 262kJ/mol. HTC could be an efficient way to reutilize corncob biomass into clean biofuels with high calorific value.

A comparative study on kinetic and thermodynamic studies for pyrolysis of corn-cob with and without aluminium oxides catalyst using thermogravimetric analysis

ABSTRACT The utilization of corncob residues in pyrolysis offers a promising source for both renewable energy and chemical production. In this study, corncob was decomposed in the presence of aluminum oxide nanoparticles (Al2O3 NPs) catalyst using a fixed bed reactor under an inert atmosphere. Pyrolysis of corncob was carried out in the presence of Al2O3 NPs at different heating rates i.e. 5, 10, 15 and 20°C/min in an oxygen-free atmosphere using TGA technique. Kinetic and thermodynamic studies were performed using the best fit models including Ozawa–Flynn–Wall (OFW), Kissinger–Akahira–Sunose (KAS) and Friedman methods. The average activation energies for Friedman, OFW, KAS were 177.3, 162.9 and 167.8 kJ/mol, respectively for pure corncob and 111.0, 102.5 and 118.06 kJ/mol, respectively for Al2O3-corncob sample. Activation energy was found to be the lowest in the OFW model. Results showed that the presence of Al2O3 NPs catalyst not only reduced pyrolysis temperature and activation energy but also improved the quality of bio-oil.

Physicochemical Characterization, Thermal Behavior, and Pyrolysis Kinetics of Sewage Sludge

Pyrolysis is an energy recovery technique with significant potential for managing wastewater treatment plant byproducts. This research aims to investigate the physicochemical and thermal properties of Moroccan sludge, as well as the behavior of its decomposition during pyrolysis at three different heating speeds (5, 10, and 20 K/min). Characterization of the sludge before pyrolysis through ultimate analysis, proximate analysis, FTIR spectroscopy, and XRD revealed that the sludge consists predominantly of organic matter, with a volatile matter rate of 48%, an ash rate of 37%, and a higher heating value (HHV) of 15 MJ/kg. The TGA-DTG curves identified four distinct stages in the sludge decomposition process: drying, decomposition of organic matter, degradation of calcium carbonate, and decomposition of inorganic matter. Using TG-MS analysis, the principal gases identified during pyrolysis were H2O, H2, CH4, CO2, CO, NO, and SO. The average activation energies (Ea) determined through kinetics models were found to be 413.4 kJ/mol for the Kissinger–Akahira–Sunose (KAS) model, 419.6 kJ/mol for the Flynn–Wall–Ozawa (FWO) model, and 416.3 kJ/mol for the Starink model. The values of Ea and the pre-exponential coefficient (A) obtained through the KAS, FWO, and Starink techniques are consistent with ΔG values ranging between 152 and 155 KJ/mol. The positive ΔS values range from 0.003 to 1.415 kJ/mol.K, indicating the complexity of the sludge response during pyrolysis and the spontaneity of the chemical reaction at high temperatures. The kinetic data obtained serves as a pillar for the development and improvement of sewage sludge pyrolysis systems, reinforcing their role in sustainable energy production.

Exploring multistep bischofite waste pyrolysis: insights from advanced kinetic analysis and thermogravimetric techniques.

Pyrolysis technology is crucial for realizing waste bischofite resource utilization. However, previous studies overlooked the complexity of multistep pyrolysis, resulting in a lack of thorough knowledge of the pyrolysis behavior and kinetics. The pyrolysis products were characterized using XRD and FTIR to indicate the bischofite pyrolysis behavior. Additionally, the multistep kinetics was studied using the segmented single-step reaction (SSSR) and Fraser-Suzuki combined kinetic (FSCK) methods. The results show that the bischofite pyrolysis is divided into dehydration and hydrolysis. The former refers to removing crystalline water from MgCl2·nH2O (n = 4,6). At the same time, the latter is related to the removal of HCl, characterized by the strengthening of the Mg-O bond in the FTIR analysis and the emergence of MgOHCl·1.5H2O in the XRD examination. The two main stages are divided into three dehydration reactions (D-1, D-2, D-3) and three hydrolysis reactions (H-1, H-2, H-3) by DTG-DDTG or Fraser-Suzuki deconvolution. Compared with the SSSR method, the FSCK method has improved model repeatability for multistep kinetic parameters. Following Fraser-Suzuki deconvolution, the FSCK method creates almost the same activation energy results when using the Friedman (FR), Kissinger-Akahira-Sunose (KAS), and Vyazovkin (VZK). This work provides fundamental data to promote the maximizing waste bischofite resource utilization.

Kinetic study of pyrolysis of waste polystyrene and polyethylene mixture using novel non‐isothermal method

AbstractA tremendous increase in municipal plastic waste is observed due to high consumption of polymers. With the passage of time the available landfills for discarding of waste plastics decrease whereas, appropriate recycling methods for waste plastics gaining more and more importance. In the present work thermal decomposition of polystyrene (PS) and polyethylene (PE) waste mixture was carried out at different heating rates (5, 10, 15 and 20 °C/min) in a thermogravimetric analyzer (TGA). Thermogravimetric data obtained was further interpreted using new developed non‐isothermal integral method and compared it with several kinetic models i. e., Coats Redfern (CR), Ozawa Flynn Wall (OFW), Kissinger‐Akahira‐Sunose (KAS), Achar and Criado‐Dollimore (CD). The activation energy (Ea) calculated using CR, OFW, KAS, Achar and CD models were found to be in the range of 92.7–130.6, 85.3–120.1, 82.1–113.2, 114.8–162.1 and 95.4–134.4 kJmol−1 respectively, whereas Ea determined by using new developed non‐isothermal method was found to be in the range 70.9 to 106.3 kJmol−1.By comparison the activation energies, it has been concluded that new integral method gave the sharp range and consistent value with highest correlation coefficient, indicating that new developed non‐isothermal method is most suitable for determination of kinetic parameters. The kinetic parameters seem to be very helpful in investigating the reaction mechanism of the solid‐state reactions in real system and will give an opportunity to develop the mechanism of the decomposition reaction.

Investigating the catalytic effect of nanoferrites additives on the thermal decomposition of ammonium perchlorate and burning rate modification of the composite solid propellants

The co-precipitation method was used to synthesize nanosize copper ferrite (CuF) and cobalt-copper-nickel ferrite (CoCuNiF). Physico-chemical characterization of material was done using powder X-ray diffraction, Raman, UV–Vis, and atomic force microscopy (AFM). The effect of 1 % by mass additives on the thermal decomposition and kinetics parameters of ammonium perchlorate (AP) was investigated using non-isothermal isoconversional methods such as Flynn wall Ozawa (FWO), Kissinger Akahira Sunose (KAS), and Starink. The burning rate enhancement and ignition delay study were also investigated. The catalysts can decrease the activation energy of AP by 48 % along with increasing the burning rate of the corresponding composite materials. Both the catalysts can be successfully used for enhancing the burning performance of propellants and hence can be used for rocket and missile propulsions.

Spiral gas-solid two-phase flow continuous mechanochemical synthesis of salophen complexes and catalytic thermal decomposition of ammonium perchlorate.

Although mechanochemistry is increasingly becoming an alternative to traditional chemical synthesis, highly efficient continuous mechanochemical synthesis techniques are still rare. In this work, a novel spiral gas-solid two-phase flow (S-GSF) synthesis technique for the mechanochemical synthesis of salophen complexes has been reported, which is an approach for continuous synthesis based solely on airflow impacting the reaction. The synthesis of salophen-Br-Cu was used as a model reaction to optimize the reaction conditions, and three other salophen complexes, namely, salophen-Br-Co, salophen-Br-Ni, and salophen-Br-Zn were synthesized on this basis. The structure and thermal stability of the obtained products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, UV-vis spectroscopy, nuclear magnetic resonance spectroscopy, scanning electron microscopy, and differential thermal analysis (DTA). The results showed that these complexes can be obtained continuously at a rate close to 4 g min-1, and the corresponding space-time yield is close to 1.2 × 105 kg m-3 day-1. In addition, DTA was used to analyze the catalytic performance of the complex for ammonium perchlorate (AP). The results showed that compared to the conditions for pure AP, salophen-Br-Co and salophen-Br-Cu could significantly reduce the high-temperature decomposition of AP pyrolysis to 77.0 and 102.1 °C, respectively. According to the method of Kissinger calculations, the Ea of AP decomposition decreased from 217.3 kJ mol-1 to 131.0 and 118.5 kJ mol-1, respectively. The TG data at different heating rates were analyzed using two isoconversion methods, i.e. Flynne-Walle-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS). The activation energies of AP, AP + 10 wt% salophen-Br-Co, and AP + 10 wt% salophen-Br-Cu were calculated. When the conversion degree (α) is between 0.1 and 0.9, the Ea values obtained from the two isoconversion methods are similar and exhibit certain matching. These two isoconversion methods also confirm Kissinger's calculations.

AVALIAÇÃO DA DEGRADAÇÃO TÉRMICA DO CAROÇO DE ABACATE RESIDUAL PARA A PRODUÇÃO DE BIOCARVÕES

EVALUATION OF THERMAL DEGRADATION OF RESIDUAL AVOCADO SEED FOR BIOCHAR PRODUCTION. The thermal degradation kinetics of avocado seed biomass (Persea americana) was investigated at the heating rates of 5, 15, 20 and 25 ºC min-1 using thermogravimetric (TGA) and differential thermogravimetric (DTG) analysis techniques in the temperature range from ambient to 780 ºC. Chemical analysis of the avocado seed resulted in: 51.4% cellulose, 42.4% hemicellulose, 20.1% lignin, 2.1% ash, 5.6% extractives. The pyrolysis products were characterized via FTIR, SEM/EDS. The isoconversional methods of Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) have yielded activation energy, Eα, varying from 36-323 kJ mol-1, respectively. The calorific value of biochars produced in the present study in the range of 265 to 475 ºC was 16,17 to 20,24 MJ kg-1, respectively, which are comparable to those reported values in the literature. Analyzing the DTG simultaneously with the addition of thermal energy, it can be seen that low molecular weight compounds represent the first degradation curves, followed by hemicellulose, cellulose and, lignin. The results obtained in the present work indicate that its feasible to prepare biochars with tunable properties from residual avocado seeds using a slow pyrolysis process, adding commercial value and reducing the environmental impact caused by the inadequate disposal of lignocellulosic materials.

Thermal investigation of NbSe2 nanoparticles synthesized through a temperature-dependent sonochemical method.

Due to their unique size-dependent properties, transition metal di-chalcogenide nanoparticles are trending in research for their potential to revolutionize next-generation electronics, energy storage, and catalytic processes. This study addresses the effect of temperature when synthesizing NbSe2 nanoparticles via the sonochemical method at three different temperatures, room temperature (R.T.), 70 °C, and 100 °C. Energy Dispersive X-ray Analysis (EDAX) confirmed the high purity of NbSe2, with the sample synthesized at 70 °C, displaying the accurate stoichiometric ratio. X-ray diffraction (XRD) analysis revealed that all samples maintained the hexagonal phase of NbSe2, with 70 °C exhibiting superior crystallinity due to their crystallite size, lowest dislocation density, and minimal internal strain. Thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) analyses, demonstrated that the sample synthesized at 70 °C had the highest thermal stability, with the lowest total weight loss and most consistent mass loss behavior. Kinetic parameters were evaluated using the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods, determining activation energy (E a), pre-exponential factor (A), change in activation enthalpy (ΔH*), change in activation entropy (ΔS*), and Gibbs free energy change (ΔG*). Also, the sample synthesized at 70 °C exhibited the highest E a, indicating superior thermal stability and favorable reaction kinetics. The findings underscore the significant impact of synthesis temperature on the structural and thermal properties of NbSe2 nanoparticles, with the sample synthesized at 70 °C demonstrating optimal characteristics. This study provides valuable insights into temperature-dependent synthesis and the thermal behavior of NbSe2 nanoparticles, highlighting their potential in various technological applications.

Research on the characteristics of pressured pyrolysis products of marine plastics

The problem of marine plastic pollution, mainly composed of polyolefin plastics, is becoming increasingly serious, and reducing marine plastic pollution is urgent. Pyrolysis, as a promising technology for treating polyolefin plastics such as polystyrene (PS), has great potential in addressing marine plastic pollution issues. In order to explore the possibility of resource utilization of marine plastics, this article studied the effect of pressure changes on the pyrolysis products of marine plastics. Marine PS was prepared by soaking routine PS in artificial seawater and air drying, and the most significant difference between the two was found to be the salt attached to the surface. The dynamic characteristics of marine PS were analyzed using Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods, and the apparent activation energy of marine PS calculated by FWO and KAS methods are 102.94 kJ·mol−1 and 95.76 kJ·mol−1, respectively. The effect of pressure at different temperatures on the pyrolysis products of marine PS was studied. The results indicate that the yield of pyrolysis oil decreases as the pressure is increased, while solid products are obtained from scratch. The increase in pressure will gradually make the composition of the thermolytic gas become monotonous. Under critical pressure, pressurization promotes an increase in CH4 content while reducing H2 content, causing the lower heating value of pyrolysis gas to increase to 4.355 kJ·g−1. Analysis of oil content found that increasing pressure promotes the growth of Benzene Toluene Ethylbenzene & Xylene (BTEX) to 33.61%, but excessive pressure can significantly reduce the higher heating value from 42.116 MJ·kg−1 to 31.825 MJ·kg−1. The solid products were characterized using FTIR and it was found that pressure did not have a significant impact on surface functional groups. Increasing the pressure properly promotes the agglomeration of amorphous carbon.

Co-pyrolysis of thermoplastic polyurethane with paulownia wood: Synergistic effects on product properties and kinetics

Co-pyrolysis of plastics and biomass offers an effective approach for waste disposal. In this study, the synergistic effects during the co-pyrolysis of thermoplastic polyurethane (TPU) and paulownia wood (PAW) were investigated in terms of pyrolysis kinetics and product properties using tube furnace, TG-FTIR and GC/MS. The results revealed that co-pyrolysis promoted the material pyrolysis and facilitated the pyrolysis process taking place at low temperatures. By adopting the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO) and Starink methods, the average activation energies of pure TPU, PAW, and TPU/PAW blends with a 1:1 mass ratio were determined to be 139 kJ/mol, 288 kJ/mol, and 126 kJ/mol. It is indicated that co-pyrolysis significantly reduced the activation energies and enhanced reactivity. Tube furnace experiments demonstrated that TPU/PAW blend with 1:1 mass ratio exhibited the highest synergism. The TPU melt acted as a physical barrier, leading to increased production of char and oil, and lower production of volatile gas. In the pyrolysis oil, the synergistic effect effectively hindered a formation of alcohol phenols. In the meanwhile, the synergistic effect also boosted generations of aliphatic compounds and ketones, increasing the heat value use of pyrolysis oil. Furthermore, a reaction pathway and mechanism of co-pyrolysis of TPU and PAW was proposed. The active molecules and free radicals generated by the pyrolysis of PAW promote the hydrogen transfer cyclization of polyester polyols decomposed by TPU, and the hydrogen free radicals released by TPU promote the depolymerization and activation of PAW. Moreover, the catalytic effect of alkali metal elements in PAW promotes the synergistic effect. The results of the study provide a basis for the co-pyrolysis of waste plastics and biomass to achieve high value utilization of waste.

Research on the Combustion Performance of Municipal Solid Waste in Different Sorting Scenarios: Thermokinetics Investigation via TG-DSC-FTIR-MS.

Waste sorting is regarded as one of the most important strategies for municipal solid waste (MSW) management. The changes in the combustion parameters after MSW sorting had a significant impact on the actual operation of the boiler. In the present study, the effects of heating rate on combustion characteristics and dynamics of MSW in different sorting scenarios were studied using the thermogravimetry (TG)-differential scanning calorimetry (DSC)-Fourier transform infrared (FTIR)-mass spectrometry (MS) technique. TG-DSC analysis showed that the heat released from MSW combustion at different heating rates ranged from 1394.1 to 4130.1 J/g. According to the TG-DTG curves, the combustibility of 30% sorted MSW was increased by 1.2 times compared to that of the unsorted scenario. In the 30% sorted scenario, the average activation energies were estimated to be 161.24 and 159.93 kJ/mol based on the Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods, respectively. Based on the Coats-Redfern (CR) method, the minimum activation energies for unsorted and 20% sorted scenarios were 148.74 and 135.53 kJ/mol at 523 to 606 K, respectively, while they were 29.42 and 33.22 kJ/mol at 606 to 780 K. XRF analysis showed that the alkali and alkaline earth metal oxides in the ash contributed to a high risk of slagging and scaling. This work can provide a scientific basis for the real situation of MSW incineration.

Thermal degradation kinetics, thermodynamics and pyrolysis behaviour of polycarbonate by TGA and Py-GC/MS

This paper elucidates the thermal and catalytic (mordenite and y-zeolite) pyrolysis characteristics of Polycarbonate (PC) as well the kinetics and thermodynamic parameters of the thermal decomposition of PC. Three distinct isoconversional methods, namely the Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starkin methods, were employed to evaluate the kinetic and thermodynamic parameters. The average activation energies determined with the KAS, FWO, and Starink methods were 245.81, 235.36, and 249.99 kJ/mol respectively, and they were reduced by 17 % and 21 % when mordenite and y-zeolite were utilized as catalysts, respectively, according to the calculations performed with the KAS method. Py-GC/MS analyses showed that phenolic components were found to be dominant in the oil product obtained under non-catalytic conditions. Micropores in the structure of y-zeolite constitute 54.4 % of the total surface area, while micropores in the structure of mordenite constitute 95.5 % of the total surface area. Depending on the structure of the catalysts used, phenolic components decreased slightly, and aromatic and PAH (Polycyclic Aromatic Hydrocarbons) components replaced these components. As a result, phenolic compounds in the oil product obtained with y-zeolite (56.7 %) were less than those produced with mordenite (61.02 %). PAHs were 12.9 % and 7.5 % in the presence of y-zeolite and mordenite, respectively. Thus, the results evidence the molecular size of zeolite catalysts, as well as their acidic structure, which are crucial factors in the conversion of phenolic compounds.