Non-isothermal Pyrolysis Research Articles

Non-Isothermal Pyrolysis of Xylan and Lignin: A Hybrid Simulated Annealing Algorithm and Pattern Search Method to Regulate Distributed Activation Energies

Non-Isothermal Pyrolysis of Xylan and Lignin: A Hybrid Simulated Annealing Algorithm and Pattern Search Method to Regulate Distributed Activation Energies

Non-Isothermal Pyrolysis of Xylan and Lignin: A Hybrid Simulated Annealing Algorithm and Pattern Search Method to Regulate Distributed Activation Energies

Non-Isothermal Pyrolysis of Xylan and Lignin: A Hybrid Simulated Annealing Algorithm and Pattern Search Method to Regulate Distributed Activation Energies

A ReaxFF molecular dynamic study on pyrolysis behavior and sulfur transfer during pyrolysis of vulcanized natural rubber

In this work, ReaxFF molecular simulations were performed to study the pyrolysis behavior of chemical cross-linked natural rubber (NR) under non-isothermal and isothermal conditions. Three different sulfur vulcanized NR models were established and simulated to study the effect of inner sulfur structure on NR decomposition behavior and sulfur evolution in comparison with carbon cross-linked structure. To understand the NR decomposition with temperatures, the non-isothermal simulations were performed between 300 and 3800 K at a 50 K ps−1 heating rate. The results reveal that the decomposition process can be classified into four stages: 1) Structure adjustment; 2) Decomposition of the main carbon chains; 3) Secondary decomposition of heavy tar; and 4) Deep decomposition of light tar. Based on the results of non-isothermal pyrolysis, four different temperatures were selected for the isothermal simulations. Compared with carbon cross-linked NR, sulfur cross-linked structures facilitate the generation of C2H4 and C4H6 in the gas phase at low temperatures. At higher temperatures, more heavy tar is generated. Regarding the sulfur evolution, the sulfur-containing products mainly include H2S, thiophene, sulfide, and thiol. The distribution of sulfur-containing products with temperatures follows the similar pattern with the product distribution of main compounds. At higher temperatures, most sulfur exists in the form of thiophene compounds. In particular, the structure with single CS cross-links facilitates the generation of H2S at low temperatures. The results of this work provide insight into the sulfur transformation and pyrolysis behavior of vulcanized NR.

Investigation of non-isothermal pyrolysis kinetics of waste industrial hemp stem by three-parallel-reaction model

The evaluation of pyrolysis kinetics for waste industrial hemp stem (IHS) is essential to achieve the high-value utilization of agricultural waste. In present study, firstly, non-isothermal pyrolysis experiments of IHS were performed at different heating rates using a thermogravimetric analyzer. Then, the kinetic triplets (apparent activation energy, pre-exponential factor, and reaction mechanism) of the three pseudo components for IHS (hemicellulose, cellulose, and lignin) were determined by a three-parallel-reaction model. Moreover, the pyrolysis products were also characterized via FTIR and SEM. The results showed that the apparent activation energies of hemicellulose, cellulose and lignin were 86.523, 113.257 and 197.961 kJ/mol, respectively; the pre-exponential factors were 6.887 × 107, 8.179 × 109 and 1.801 × 1015 s−1, respectively; and the reaction mechanism functions were f(α) = α1.35629(1-α)0.34832[-ln(1-α)]−1.20128, f(α) = α3.42900(1-α)0.01288[-ln(1-α)]-2.84445, f(α) = α0.68738(1-α)3.09313[-ln(1-α)]-1.58522, respectively. The release temperature for volatile products of IHS pyrolysis was mainly between 440 and 840 K. IHS as an agricultural waste is a suitable feedstock to produce renewable energy.

Chemical Feedstock Recovery via the Pyrolysis of Electronically Heated Tobacco Wastes

The pyrolysis of waste electronically heated tobacco (EHT), consisting of tobacco leaves (TL), a poly-lactic acid (PLA) filter, and a cellulose acetate (CA) filter, was investigated using thermogravimetric (TG) and pyrolyzer–gas chromatography/mass spectrometry (Py-GC/MS) analysis. The pyrolytic properties of waste EHT obtained after smoking were comparable to those of fresh EHT. Although the maximum decomposition temperatures (TmaxS) of waste TL and CA were similar to those of fresh EHT components, the Tmax of waste PLA was slightly higher than that of fresh PLA due to smoldering. The Tmaxs of PLA and CA were lowered when they were co-pyrolyzed with TL due to interactions between pyrolysis intermediates. The apparent activation energies for the non-isothermal pyrolysis of waste EHT components were higher than those of fresh EHT components. Py-GC/MS analysis results indicated that considerable amounts of chemical feedstocks, such as nicotine and limonene from TL, caprolactone and lactide from PLA, and acetic acid and triacetin from CA, can be recovered by simple pyrolysis of EHT. Co-pyrolysis of TL, PLA, and CA revealed that the experimental amount of lactide was much larger than the calculated value, suggesting its synergistic formation.

Investigation of kinetic and thermodynamic parameters approaches to non-isothermal pyrolysis of mustard stalk using model-free and master plots methods

Present work based on thermogravimetric analysis (TGA) to decipher in detail the pyrolysis of mustard stalk (MS) for investigating its potential for bioenergy feedstock at three heating rates (5, 10, and 20 °C/min). The thermal degradation behaviors of MS were carried out at three heating rates (5, 10, and 20 °C/min). The kinetic and thermodynamic parameters were examined using model-free isoconversional Flynn- Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) model. The obtained activation energy for pyrolysis of MS using FWO and KAS to be 132.47 and 130.62 kJ/mol. Kissinger method was used to compute pre-exponential factor found to be in the range of 105 to 1016 s−1 at different heating rates. The average ΔH was 127.70, and 125.8 kJ/mol and ΔG is 127.74 and 127.87 kJ/mol from FWO and KAS respectively, all ΔH positive indicated endothermic nature. The Coats-Redfern approach was used to estimate the thermal degradation reaction mechanism, which revealed that the diffusion model was best suited to reflect the degradation process involving both exothermic and endothermic reactions. The analysis can help augment the experimental studies, and physicochemical characterization revealed its fuel characteristic since MS is sustainable and promising biomass for alternative processes in terms of waste management strategies.

The influence of calcium lignosulphonate addition on non-isothermal pyrolysis and gasification of demineralised bituminous coal fines

• Coal fines were demineralised using acid de-ashing treatment. • CaLS added to the coal fines and demineralised coal in different proportion showed an increase in compressive strength. • CaLS blended samples showed higher reactivity when compared to the demineralised coal and coal fines. • 5% CaLS addition did not influence coal gasification rate significantly. • An increase in CaLS blends correlates with an increase in reactivities. Amorphous calcium lignosulphonate (CaLS), a by-product of the paper industry, was evaluated as an adhesive to bind demineralised bituminous coal fines in various weight percentage ratios. Sequential acid (HCl, HF, HCl) leaching was used to reduce mineral matter content in the coal fines. The pyrolysis and gasification of the samples were investigated in laboratory-scale experiments to determine the effect of the CaLS addition on the pyrolysis and gasification reactivities. Coal-CaLS blends consisting of 5, 10, and 15% calcium lignosulphonate were prepared, compressed into pellets, and characterised using proximate, X-ray diffraction, and X-ray fluorescence analyses. An increase in binder concentration increases the mechanical strength of the pellets due to the increased interparticle contact area. The relative coal gasification reaction reactivity (1/T max and 0.5/T 50 ), which was determined from the derivative thermogravimetry curves, increases with CaLS addition. The experimental results revealed that these wastes (coal fines and calcium lignosulphonate) could be utilised in thermochemical processes. Utilising these wastes will reduce the environmentally unfriendly volumes of amorphous calcium lignosulphonate and coal fines particles.

Influence of chemical and crystallite parameters of asphaltenes on their thermal decomposition and electrokinetic behavior

This study aims to explore the influence of chemical composition and structural features of asphaltenes from heavy and light crude oils on their thermal degradation, kinetic parameters and electrophoretic mobility. Non-isothermal pyrolysis experiments were performed through thermogravimetric (TG) analysis whereas electrophoretic mobility was evaluated through zeta-potential measurements. Results showed that thermal degradation profile, reaction rate and kinetics of the asphaltenes pyrolysis can be associated to their XRD structural parameters such as aromatic-stack height, aromatic-sheet diameter, and size of peripheral alkyl groups. In addition, the influence of crystallite parameters, salinity, sulfur, and metal content on the asphaltenes electrokinetic behavior, was explored.

The characteristics and mechanism for the formation of tars from low temperature pyrolysis of lignite

In this paper, the effect of pyrolysis conditions on low-temperature formation of tars characteristics and viscosity of lignite was investigated in a self-researched fixed bed reactor. The relationship between tar quality parameters and its formation and viscosity characteristics was investigated by multiple linear regression. The composition characteristics of low temperature tar were also investigated. The results showed that the yield and viscosity of tar increased with the increase of heating rate and pyrolysis temperature. Low temperature tar started to escape at 350 °C and reaches a maximum at 600 °C. The maximum tar yield was obtained at 550 °C–600 °C, 0.31%/min. The tar viscosity increased significantly after 550 °C, and the tar yield of isothermal pyrolysis was higher than that of non-isothermal pyrolysis after 500 °C. The tar yield under hydrogen atmosphere was higher than that under nitrogen, carbon dioxide, methane and carbon monoxide atmosphere. The tar yield increased gradually with the increasing of H2 flow rate, until it reached the maximum at the flow rate of 720 ml/min, which was 12.58%. The mathematical models of tar formation and viscosity characteristics of Yunnan lignite during low temperature pyrolysis were Yieldtar ( % )=12.14 H/C+48.35O/C−12.54fa+0.29Ad and Viscositytar( mPa⋅s )=14.99 H/C+62.53O/C−0.39fa, respectively. The content of aliphatic and aromatic components in tar increased with the increase of pyrolysis temperature, while the content of polar substances decreased gradually. The content of aliphatic and aromatic components was more than 53%, and the polar compounds content dropped to about 41.7% at 600 °C.

Thermal degradation kinetics and structural characterization of sodium bentonite

ABSTRACT The thermal-decomposition behavior of a sodium-bentonite sample was investigated in this study. Non-isothermal pyrolysis tests were performed through simultaneous thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis to characterize the thermal-behavior of the bentonite sample in a temperature range from ambient to 750°C. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscopy (SEM) were used to determine the changes in mineralogy, structural features and morphology of bentonite before and after pyrolysis at 750°C. Iso-conversional methods were used to obtain kinetic-parameters such as the activation energies whereas Coats-Redfern (CR) method was used to find the most probable reaction mechanisms involved on the bentonite pyrolysis. XRD analysis showed that bentonite sample was mainly composed of sodium montmorillonite and a minority of other minerals such as quartz, plagioclase, alkali feldspar, cristobalite and calcite. Structural collapse of the clay mineral due to the thermal treatment was confirmed through XRD, FT-IR and SEM. Results indicated that thermal-decomposition of bentonite is carried out in two stages: a dehydration following a diffusion-controlled kinetics with an average activation energy of 72.23 kJ/mol, and a dehydroxylation characterized by a second-order kinetics with an average activation energy of 228.28 kJ/mol.

Mathematical Modeling of the Nonisothermal Pyrolysis of Sorghum Biomass Based on a Three-Component Kinetic Model

Mathematical Modeling of the Nonisothermal Pyrolysis of Sorghum Biomass Based on a Three-Component Kinetic Model

Combustion Behavior of Algal Biochars Obtained at Different Pyrolysis Heating Rates.

In this work, the combustion performance of Chlorella vulgaris (CV), Dunaliella salina (DS), and Haematococcus pluvialis (HP) algal biochars was analyzed based on the multicomponent method. The biochars were obtained via nonisothermal pyrolysis of raw algal biomasses at three different heating rates (i.e., 30, 40, and 50 °C/min), and biochar combustion was performed from 200 to 700 °C at a heating rate of 5 °C/min. The complex oxidative reaction of algal biochar was resolved into combined reactions of multiple pseudo-components based on the peak deconvolution method using a bi-Gaussian model. The activation energies (Ea) for each pseudo-component (PC) of all biochar samples were calculated by the Coats–Redfern isoconversional method and four kinetic models (i.e., diffusion, nucleation, order-based, and shrinking core models). The results showed that the highest Ea values were predicted by the diffusion model. Except that the Ea for the first PC of CV biochar decreased by 16.45%, the Ea values for all other biochar samples generally increased with increasing the pyrolysis heating rate. Moreover, when the diffusion model was used, the Ea for the second PC of CV biochar increased by 50.87%, that for the first PC of DS biochar increased by 16.85%, and those for the first and third PCs of HP biochar increased by 4.66 and 11.66%, respectively. In addition, the combustibility index (Sn) was evaluated based on the ignition and burnout temperatures as well as the mean and maximum weight loss rates. Generally, the combustion performance of all biochar samples was good at a low temperature but deteriorated toward a high temperature. As the pyrolysis heating rate increases, an overall increase in the combustion quality was also seen for the second PC of CV biochar and the first PCs of DS and HP biochars because their Sn increased from 2.70 × 10–15 to 3.07 × 10–15 °C–5, 2.53 × 10–13 to 3.88 × 10–13 °C–5, and 3.00 × 10–13 to 3.26 × 10–13 °C–5, respectively.

Investigation on the kinetic behavior, thermodynamic and volatile products analysis of chili straw waste pyrolysis

Recently pyrolysis has become the sustainable and huge environmental-friendly method for agricultural straw waste (ASW) to evaluate the bioenergy potential. Whereas, the thermal decomposition behavior of chili straw waste (CSW) has not never been explored. This present research systematically studied the bioenergy potential of CSW using three multiple direct characterization tools, including thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectrometer, and Curie-point pyrolyzer-gas chromatograph/mass spectrometer (CPP-GC/MS). Thermal decomposition of CSW has been investigated by TGA under the non-isothermal pyrolysis temperature at four heating rates of 5, 10, 20, and 30 °C min−1, respectively, which can be separated into three processes. Four isoconversional model-free methods such as Kissinger-Akahira-Sunose (KAS), Friedman, Flynn-Wall-Ozawa (FWO), and Starink, were determined the kinetic, ΔH, ΔG, and ΔS of CSW pyrolysis. The average activation energy (Ea) for CSW pyrolysis obtained by Starink, KAS, and FWO methods (195.48, 199.70, and 196.37 kJ mol−1) were lower than that Friedman model (227.15 kJ mol−1). FTIR analysis result showed that CSW was rich in oxygen-containing species and had the great potential for its valuable conversion into renewable bio-fuel. Besides, based on the CPP-GC/MS analysis, oxygenated components including phenols, esters, and acids were major volatile products (VPs) of CSW.

Investigation of co-pyrolysis characteristics of high-ash Indian coal and rice husk

This study investigates the non-isothermal pyrolysis characteristics of a low-grade, high ash Indian coal, and rice husk using a thermogravimetric analyzer (TGA). A series of thermo-gravimetric experiments are conducted to examine the effects of coal and biomass blending on their thermal degradation behavior and synergetic effects in the nitrogen atmosphere. The thermo-gravimetric (TG) curves show two distinct tips where the larger tip is obtained for biomass as compared to the coal. The thermogravimetric study does not demonstrate any significant synergetic interaction between the biomass and high ash coal in the blends, and the additive rule describes the behavior of their combined pyrolysis. The activation energy and preexponential factor for coal and biomass are calculated based on the TGA data using the Friedman method. the corresponding calculated mean activation energy values for the biomass and Indian low-rank coal were found to be 203.463 KJ/mol, and 66.97 KJ/mol respectively.

Pyrolysis of electronic waste and their mixtures: Kinetic and pyrolysate composition studies

Electronic waste (e-waste) constitutes an important component of solid waste, and recovering valuable chemicals and resources from it holds a high priority in solid waste management. The various chemical functionalities present in the organic fraction of e-waste can be converted to valuable chemicals and fuel molecules by pyrolysis process. In this study, non-isothermal pyrolysis of waste printed circuit board (PCB), waste keyboard keys (KB), and their equal composition mixture is conducted in a thermogravimetric analyzer at different heating rates. The kinetic analysis was carried out using isoconversional method of Vyazovkin and the multi-Gaussian distributed activation energy model (DAEM). The average apparent activation energies of pyrolysis of PCB, PCB: KB, and KB, determined using the Vyazovkin method, were 188.4, 167.6, and 169 kJ mol−1, respectively. The apparent activation energy determined using the DAEM varied in a wide range owing to the decomposition of multiple pseudo-components. Analytical pyrolysis coupled with gas chromatograph/mass spectrometer (Py-GC/MS) was used to identify the pyrolysates from PCB, KB, and their mixtures at 500 °C. The major pyrolysate functional groups from PCB were phenolic derivatives (36%), oxygenates (26%), and phenyl phosphates (14.4%), while KB pyrolysis yielded aromatics (52%) containing styrene as the major compound. Pyrolysis of mixtures resulted in a net increase in the selectivity to aromatics with a concomitant decrease in oxygenates suggesting dehydration and decarboxylation to be the major reactions. A significant amount of nitriles was produced from the pyrolysis of mixtures owing to the decomposition of acrylonitrile-butadiene-styrene plastic that constitutes KB.

Determination of hydrocarbon generation potential of a non-isothermal pyrolysis of Faraghun and Sarchahan Formations in Coastal Fars and the Persian Gulf, Iran

Source rock assessment is a key step in any petroleum exploration activity. The results of Rock-Eval analysis showed that Sarchahan Formation was in the late oil window, while the Faraghun and Zakeen Formations were just in the early stages of the oil window. Furthermore, Sarchahan, Zakeen and Faraghun Formations exhibited different kerogen types (types-Ⅱ, types-Ⅲ and type-Ⅲ, respectively). Refining the kinetic parameters using the OPTKIN software, the error function returned error values below 0.1, indicating accurate optimization of the kinetic parameters. Based on the obtained values of activation energy, it was clear that Sarchahan Formation contained type-Ⅱ kerogen with an activation energy of 48–52 kcal/mol, while Zakeen and Faraghun Formations contained type-III kerogen with activation energies of 70–80 kcal/mol and 44–56 kcal/mol, respectively. The geographical distribution of the samples studied in this work, it was found that the organic matter (OM) quantity and quality increased as one moved toward the Coastal Fars in Sarchahan Formation. The same trend was observed as one moved from the southern coasts of Iran toward the shaly and coaly portions of Faraghun Formation in the center of the Persian Gulf.©2021 China Geology Editorial Office.

Effect of High Pressure on Nonisothermal Pyrolysis Kinetics of Oil Shale and Product Yield

The current work presents a comprehensive study on nonisothermal high-pressure pyrolysis kinetics of oil shale and the influence of pressure on product yield. High-pressure thermogravimetric analys...

The role of water during gas generation

Resources of coal-derived gas in the deep strata are found abundant in China. Recent advances in petroleum geochemistry suggest water may contribute hydrogen and oxygen to the formation of hydrocarbons and oxygenated alteration production. However, the role of water during gas generation has been in debate due to conflicting research results. In this study, a Jurassic coal sample from the Kuqa depression, Tarim Basin, China was artificially matured by nonhydrous pyrolysis and hydrous pyrolysis at isothermal (330 °C, 350 °C, 370 °C for 72h) and non-isothermal (440 °C, 470 °C and 500 °C at heating rate of 2 °C/h) temperatures. Both isothermal and non-isothermal experiments generated more methane but less C3-5 hydrocarbon gases and CO2 non-hydrocarbon gas in the nonhydrous system relative to hydrous conditions. In the isothermal experiment, the nonhydrous pyrolysis generated at most 24% more methane relative to the hydrous pyrolysis, but the hydrous pyrolysis generated 5%∼87% more C3-5 hydrocarbon gas and at most 28% more CO2 relative to the nonhydrous pyrolysis. In the non-isothermal experiment, the nonhydrous pyrolysis generated 25%∼94% more methane relative to the hydrous pyrolysis, but the hydrous pyrolysis generated at most 2.56 times more C3-5 hydrocarbon gas and 1.04 times more CO2 relative to the nonhydrous pyrolysis. In general, the compositional variation trend of hydrocarbon and non-hydrocarbon gases is similar between the isothermal and non-isothermal experiments. This indicates that contribution from the supercritical water in the non-isothermal pyrolysis is not essential. With the presence of water, the secondary cracking of C3-5 alkanes in the hydrous experiments was significantly suppressed, as shown by the relatively higher yield of C3-5 alkanes in the hydrous systems. The availability of exogenous hydrogen from water in the hydrous pyrolysis inhibits the carbon-carbon bond cross linking, thus the reaction pathway of hydrocarbon generation is dominated by the thermal cracking of carbon-carbon bonds. The significant increase in CO2 in the hydrous pyrolysis indicates water is not only the source for exogenous hydrogen but also the source for the excess oxygen accounted for the formation of CO2. The overall geochemical implication of these experimental results is that it is important to consider the role of water in the hydrocarbon generation, especially in the deep strata where both geological and geochemical conditions are complex.

Application of a neural fuzzy model combined with simulated annealing algorithm to predict optimal conditions for polyethylene waste non-isothermal pyrolysis

In the present study, the waste polyethylene (PE) pyrolysis under different non-isothermal conditions was investigated to estimate the optimal conversions and pyrolysis rates. The pyrolysis study was carried out using Thermogravimetry (TG) of the virgin and the waste PE under different heating rates of 5, 10, 15 and 20 °C/min. The TG experiments indicated that the virgin and the waste PE pyrolysis processes mainly underwent in the temperature range of 390–510 °C. Subsequently, the adaptive neural fuzzy model was adopted to predict the conversions and the pyrolysis rates of the virgin and the waste PE. The optimal operating conditions in different temperature ranges were optimized by the simulated annealing algorithm (SA). Moreover, the R-squared values of the virgin PE conversions (~ 1) and pyrolysis rates (> 0.999), and the waste PE conversions (~ 1) and pyrolysis rates (> 0.999) revealed the high accuracy of the adaptive neural fuzzy model predicted results.

Evaluation of the Validity of Model-Fitting and Model-Free Methods for Kinetic Analysis of Nonisothermal Pyrolysis of Siberian Fir Bark

The kinetic parameters of the pyrolysis of Siberian fir bark were estimated by thermogravimetric analysis. The thermochemical conversion of the bark biomass was performed at heating rates of 5, 10, and 20 deg/min in an inert (argon) medium. The results of thermogravimetric and differential thermogravimetric analyses were studied by model-fitting (Arrhenius and Coats–Redfern) and model-free (Friedman and Ozawa–Flynn–Wall) kinetic methods. The most reliable values of the activation energy were obtained by the model-free Ozawa–Flynn–Wall and Friedman methods (159 and 156 kJ/mol, respectively). It was shown that using these kinetic models enables one to determine more accurate temperature ranges of decomposition of biomass components under pyrolysis conditions.