Determination of kinetic triplet, thermal degradation behaviour and thermodynamic properties for pyrolysis of a lignocellulosic biomass

Co-pyrolysis behaviors, kinetics, and thermodynamics of sludge, lignite and biomass through fixed-bed reactor experiments and thermogravimetric analysis

Co-pyrolysis behaviors, kinetics, and thermodynamic parameters of petrochemical sludge (PS), lignite (HL), and pine wood (PW) were investigated via fixed-bed reactor experiments and thermogravimetric analysis. Fixed-bed experiments showed H2 and CO2 were main gases from PS, HL, and blends, CO from PW and PS, and CO and CH4 from PS and HL. Thermal analysis indicated that ternary blends' de-volatilization had two parts dominated by PW and HL, respectively. The comprehensive de-volatilization index increased from 7.0 × 10-7 to 3.3 × 10-6 %2/(min2·°C3) as PW ratio rose from 20 % to 40 %. Effects of heating rates on pyrolysis properties, kinetics, and thermodynamics were studied using thermal analysis data. Characteristic indices increased, and activation energies decreased with HL or PW mixing; minimum activation energy was 147.2 kJ/mol for PS and HL blend. Blending lignite and biomass improved pyrolysis indices of petrochemical sludge and reduced activation energy and thermodynamic parameters, benefiting sludge disposal.

Kinetic analysis of slow pyrolysis of oily sludge at medium temperature (350 ℃-650 ℃) and the effects of heating rate on pyrolysis

ABSTRACTPyrolysis is an effective way for the harmless treatment of oily sludge. The composition, physicochemical properties, and pyrolysis of oily sludge were experimentally studied in the present study. The Starink and Coats-Redfern methods were used to analyze the pyrolysis kinetics of oily sludge. Pyrolysis of oily sludge is divided into four stages: water evaporation stage, light component evaporation stage, heavy component pyrolysis stage, and final pyrolysis stage. The light component evaporation and heavy component pyrolysis stages are the main stages of medium-temperature pyrolysis. The pyrolysis characteristic parameters under heating rates of 10, 20, 30, and 40 K/min were obtained, and the effects of heating rates on the pyrolysis characteristics of oily sludge were discussed. The results show that with the increase in heating rate, the temperature range of each stage expands, and the temperature of the pyrolysis peaks also increases, with an average increase of 14.88%. The activation energies of the main pyrolysis stages obtained by the Starink method and Coats-Redfern method are consistent. In the light component evaporation stage, the activation energies obtained by the two methods are 61.93kJ/mol and 68.6kJ/mol, while the activation energies are 294.88kJ/mol and 367kJ/mol in the heavy component pyrolysis stage. The pyrolysis mechanism functions are obtained, and the pyrolysis kinetic equations under 10, 20, 30, and 40 K/min were constructed and validated by comparison with the results of the calculated properties and experimental measurement. This study can provide a better insight into the heat and mass transfer processes of oily sludge in pyrolysis reactors for further development and optimization.

Combustion characteristics and gasification kinetics of Brazilian municipal solid waste subjected to different atmospheres by thermogravimetric analysis

This study examines the gasification kinetics of Brazilian municipal solid waste (MSW) and its components under air, CO2, and air/CO2 (70/30 vol%) atmospheres. The ignition indices of paper and plastic are 6 and 3 times that of food waste, which are 38.6 × 10-3 %/min3 and 19.6 × 10-3 %/min3, respectively, implying a faster separation of volatile compounds from the paper and plastic. The minimum Eα values of 132 kJ/mol and 140 kJ/mol have been obtained for paper waste under air and air/CO2, respectively. On CO2 condition, MSW has an average Ea value of 96 kJ/mol. Under an air/CO2 atmosphere, a high synergistic ΔW of -4.7 wt% has been identified between individual components. The presence of air and CO2 improves the oxidation and char gasification process, thus resulting in better combustion. Hence, the gasification of MSW under an air/CO2 atmosphere would improve the waste-to-energy plant's performance and minimize the CO2 emission.

Assessment and comparison of thermochemical pathways for the rice residues valorization: pyrolysis and gasification

Lignocellulosic biomass conversion applying thermochemical routes has been postulated as an alternative for generating renewable energy. This research compares energy-driven biorefineries based on two thermochemical routes addressed to upgrade rice husk and rice straw produced in the Department of Sucre-Colombia. Initially, this research analyzes the physico-chemical and structural characterization of the rice residues. Four different scenarios were proposed to compare the energy-driven biorefineries based on fast pyrolysis and gasification considering technical, economic, and environmental metrics. These biorefineries were simulated using the Aspen Plus V.14.0 software. The novelty of this research is focused on the identification of the biorefinery with the best techno-economic, energetic, and environmental performance in the Colombian context. Economic and environmental analyses were done by using economic metrics and emissions. From an economic perspective, the stand-alone gasification process did not have a positive economic margin. In contrast, the fast pyrolysis process has the best economic performance since this process has a positive profit margin. Indeed, scenario 1 (fast pyrolysis of both rice residues) presented an economic margin of 13.75% and emissions of 2170.92 kgCO2eq/kg for 10 years. However, this scenario was not energetically the best, holding second place due to the feedstock requirements, compared to gasification. The biorefinery scenario 1 has the best performance.

Investigation of the evolved pyrolytic products and energy potential of Bagasse: experimental, kinetic, thermodynamic and boosted regression trees analysis

This study explored bagasse's energy potential grown using treated industrial wastewater through various analyses, experimental, kinetic, thermodynamic, and machine learning boosted regression tree methods. Thermogravimetry was employed to determine thermal degradation characteristics, varying the heating rate from 10 to 30 °C/min. The primary pyrolysis products from bagasse are H2, CH4, H2O, CO2, and hydrocarbons. Kinetic parameters were estimated using three model-free methods, yielding activation energies of approximately 245.98 kJ mol-1, 247.58 kJ mol-1, and 244.69 kJ mol-1. Thermodynamic parameters demonstrated the feasibility and reactivity of pyrolysis with ΔH ≈ 240.72 kJ mol-1, ΔG ≈ 162.87 kJ mol-1, and ΔS ≈ 165.35 J mol-1 K-1. The distribution of activation energy was analyzed using the multiple distributed activation energy model. Lastly, boosted regression trees predicted thermal degradation successfully, with an R2 of 0.9943. Therefore, bagasse's potential as an eco-friendly alternative to fossil fuels promotes waste utilization and carbon footprint reduction.

Insights into pyrolysis of pearl millet (Pennisetum glaucum) straw through thermogravimetric analysis: Physico-chemical characterization, kinetics, and reaction mechanism

Millets and millet crop residues are gaining increasing attention. Present work provides insights into thermal degradation characteristics, pyrolysis indices, kinetic triplets, and thermodynamic parameters for pearl millet straw (PMS) pyrolysis. Pyrolysis indices revealed suitability of higher heating rates for PMS in terms of enhanced pyrolysis performance and shorter reaction time. Combined iso-conversional techniques and distributed activation energy model (DAEM) approach was employed to study kinetics of PMS pyrolysis. Average activation energy through Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, Friedman, Starink, Vyazovkin, and DAEM was found to be 189.61, 190.84, 192.71, 187.84, 193.33, and 191.08 kJ/mol, respectively. Statistical analysis through ANOVA using Tukey test demonstrated insignificant deviation for obtained activation energies. Kinetic compensation effect was employed to determine pre-exponential factor. Master plots revealed prevalence of random nucleation (R1 and R2) for α < 0.5 and diffusion (D1) and power law (P2) models for α > 0.5. Thermodynamic parameters revealed endothermic, non-spontaneous, and high degree of randomness for PMS pyrolysis.

Kinetic mechanism of wheat straw pellets combustion process with a thermogravimetric analyser

In this study, the combustion characteristics of two wheat straw pellets (WSP) (T1: 100% wheat straw and T5: 70% wheat straw; 10% sawdust, 10% biochar; 10% bentonite clay) were performed at a heating rate 20 °C/min under a temperature from 25 to 1200 °C in air atmosphere. A thermogravimetric analyser (TGA) was used to investigate the activation energy (Eα), pre-exponential factor (A), and thermodynamic parameters. The DTG/TG profile of WSP was evaluated by model-free and model-based methods and found the model-based method was suitable for WSP thermal characterisation. The result demonstrates that the thermal decomposition occurred in four stages, comprising four consecutive reaction steps. A→B→C→D→E→F. Further, the model-based techniques were best fitted with kinetic reaction models like Cn (nth-order reaction with auto-catalyst), Fn (reaction of nth order), F2 (second-order phase interfacial reaction) and D3 (diffusion control). The average Eα for Fn, Cn, D3 and F2 models were 164.723, 189.782, 273.88, and 45.0 kJ/mol, respectively, for the T1 pellets. Alternatively, for T5 pellets, the A was 1.17E+2, 1.76E+16, 5.5E+23, and 1.1E+3 (1/s) for F2, D3, Cn and Fn models. Overall, the thermodynamic properties showed that WSP thermokinetic reactions were complex and multi-point equilibrium, indicating a potentiality as a bioenergy feedstock.

Pyrolysis Characteristics and Determination of Kinetic and Thermodynamic Parameters of Raw and Torrefied Chinese Fir

Torrefaction influences the structural and physicochemical properties of biomass, thus further altering its thermal degradation behavior. In this study, the pyrolysis characteristics, reaction kinetics, and thermodynamic parameters of raw and torrefied Chinese fir (CF) were investigated. The torrefaction was conducted at 220 °C (mild) and 280 °C (severe), the pyrolysis was performed from ambient temperature to 600 °C, and four different heating rates (i.e., 5, 15, 25, and 35 °C/min) were adopted. The activation energy for pyrolysis was estimated by adopting three isoconversional methods. The master-plot method was employed to analyze the reaction mechanism. Furthermore, thermodynamic parameters, i.e., the enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS), were calculated. The average activation energy increased with the torrefaction temperature, whose values estimated by using different methods ranged from 88.57 to 97.70, from 121.04 to 126.35, and from 167.51 to 179.74 kJ/mol for raw, mildly, and severely torrefied CF samples, respectively. A compensation effect between the activation energy and pre-exponential factor was observed for all samples. The degradation process was characterized as endothermic, involving the formation of activated complexes and requiring extra energy for torrefied samples.

Thermal Stability and Non-Isothermal Kinetic Analysis of Ethylene-Propylene-Diene Rubber Composite

The purpose of this study was to investigate the thermal stability and the decomposition kinetics of ethylene-propylene-diene monomer (EPDM) composite samples loaded with and without lead powder (50, 100, and 200 phr lead) using thermogravimetric analysis (TGA). TGA was carried out at different heating rates (5, 10, 20, and 30 °C/min) under inert conditions in the temperature range of 50-650 °C. Lead addition did not significantly change the onset temperature or peak position corresponding to the maximum decomposition rate of the first derivative of the TGA curve (DTGA) (onset at about 455 °C and T_m at about 475 °C). Peak separation for the DTGA curves indicated that the main decomposition region for EPDM, the host rubber, overlapped the main decomposition region for volatile components. The decomposition activation energy (E_a) and pre-exponent factor (A) were estimated using the Friedman (FM), Kissinger-Akahira-Sunose (KAS), and Flynn-Wall-Ozawa (FWO) iso-conversional methods. Average activation energy values of around 231, 230, and 223 kJ/mol were obtained for the EPDM host composite using the FM, FWO, and KAS methods, respectively. For a sample loaded with 100 phr lead, the average activation energy values obtained via the same three methods were 150, 159, and 155 kJ/mole, respectively. The results obtained from the three methods were compared with results obtained using the Kissinger and Augis-Bennett/Boswell methods, and strong convergence was found among the results of the five methods. A significant change in the entropy of the sample was detected with the addition of lead powder. For the KAS method, the change in entropy, ΔS, was -3.7 for EPDM host rubber and -90 for a sample loaded with 100 phr lead, α = 0.5.

Pyrolysis Kinetics of Byrsonima crassifolia Stone as Agro-Industrial Waste through Isoconversional Models

This study is aimed at the analysis of the pyrolysis kinetics of Nanche stone BSC (Byrsonima crassifolia) as an agro-industrial waste using non-isothermal thermogravimetric experiments by determination of triplet kinetics; apparent activation energy, pre-exponential factor, and reaction model, as well as thermodynamic parameters to gather the required fundamental information for the design, construction, and operation of a pilot-scale reactor for the pyrolysis this lignocellulosic residue. Results indicate a biomass of low moisture and ash content and a high volatile matter content (≥70%), making BCS a potential candidate for obtaining various bioenergy products. Average apparent activation energies obtained from different methods (KAS, FWO and SK) were consistent in value (~123.8 kJ/mol). The pre-exponential factor from the Kissinger method ranged from 10⁵ to 10¹⁴ min^-1 for the highest pyrolytic activity stage, indicating a high-temperature reactive system. The thermodynamic parameters revealed a small difference between E_A and ∆H (5.2 kJ/mol), which favors the pyrolysis reaction and indicates the feasibility of the energetic process. According to the analysis of the reaction models (master plot method), the pyrolytic degradation was dominated by a decreasing reaction order as a function of the degree of conversion. Moreover, BCS has a relatively high calorific value (14.9 MJ/kg) and a relatively low average apparent activation energy (122.7 kJ/mol) from the Starink method, which makes this biomass very suitable to be exploited for value-added energy production.

Influence of lignin on coal gangue pyrolysis and gas emission based on multi-lump parallel reaction model and principal component analysis

The effects of lignin (LIG) on coal gangue (CG) pyrolysis characteristics, gas emissions, and multi-lump parallel reaction modeling are studied in this paper. The combined thermogravimetry and Fourier infrared spectrometer were used to obtain the weight loss and gas product functional group data of the co-pyrolysis of coal gangue and lignin. Gaussian peaks were used to analyze the reaction degree of different proportions of lignin added to coal gangue at different temperatures. Moreover, principal component analysis (PCA) is applied to further analyze pyrolysis reaction process. During the pyrolysis of C1L3 samples, a synergistic interaction was discovered. The optimal mixing ratio of coal gangue and lignin during pyrolysis was obtained. The influence mechanism of lignin on coal gangue pyrolysis is studied in this article, which can provide technical support for the reduction and resource utilization of coal gangue. There are six-lump parallel reactions in pyrolysis after CG and LIG are mixed. The addition of LIG changed the CO₂ release law of CG pyrolysis. The strengthening of coal gangue disposal research is of positive significance for improving the environment and increasing the utilization rate of coal.

Pyrolysis of pigeon pea (Cajanus cajan) stalk: Kinetics and thermodynamic analysis of degradation stages via isoconversional and master plot methods

Detailed analysis of thermo-kinetics, reaction mechanism, and estimation of thermodynamic parameters are imperative for the design of reactor systems in thermochemical conversion processes. Present investigation was aimed at exploring the pyrolysis potential of pigeon pea stalk (PPS) by thermogravimetric experiments at 10, 20, and 30 °C/min heating rates. Maximum devolatilization of PPS was found to take place below 480 °C. The average activation energy for PPS pyrolysis was found to be 95.97, 100.74, 96.24, and 96.64 kJ/mol by Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, Starink, and Friedman method, respectively. Statistical analysis by one way analysis of variance method by employing Tukey test revealed that the difference in activation energy estimated from different methods was insignificant. Thermodynamic parameters (ΔH, ΔS_, and ΔG) together with reaction mechanisms were also evaluated. Difference in the activation energy and enthalpy was found to be less than 5 kJ/mol. R2 and R3 models were found best fitted with experimental PPS pyrolysis data.

Thermo-chemical potential of solid waste seed biomass obtained from plant Phoenix dactylifera and Aegle marmelos L. Fruit core cell

The present study explores thermo-chemical potential of two biomasses namely; Phoenix dactylifera seed (PDS) and Aegle marmelos L core (AMP). These biomasses contain high amount of cellulose and exhibit heating value of 3-18 MJ/kg. The thermal kinetic of both the biomasses have been extensively studied using thermogravimetric analysis (TGA) at four different heating rates 5, 10, 15, and 20 °C/min. Kinetic analysis was carried out using three model-free techniques including Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink. The average activation energy has been found to be 173.75, 172.94 and 170.71 kJ/mol, for PDS whereas 170.26, 167.24 and 164.80 kJ/mol, for AMP analyzed through KAS, FWO and Starink methods, respectively. Further, among all these models, the Starink model exhibits better result for the biofuels potential point of view.

Comparative pyrolysis studies of lignocellulosic biomasses: Online gas quantification, kinetics triplets, and thermodynamic parameters of the process

This study focused on the analysis of the pyrolytic behavior of four lignocellulosic biomasses: avocado stone (AS), Agave salmiana bagasse (AB), cocoa shell (CS), and α-cellulose (CEL). According to the triplet kinetics analysis, the order of pyrolytic decomposition was AS < AB < CEL < CS. The AS was dominated by a second-order reaction, while AB followed a 2D diffusion-Valensi model. On the other hand, the pyrolysis of CS starts with an nth-order reaction and ends random nucleation model, and CEL was dominated by one-dimensional diffusion and first-order reaction. Thermodynamic studies reveal that the difference between the activation energy versus enthalpy change was<6.5 kJ/mol for all biomasses, thus showing the ease of pyrolysis reaction of these biomasses. Furthermore, the AS and AB showed that the reactions are close to thermodynamic equilibrium and stability, whereas CS and CEL indicated high reactivity.

Thermogravimetric pyrolysis of onion skins: Determination of kinetic and thermodynamic parameters for devolatilization stages using the combinations of isoconversional and master plot methods

Thermogravimetric pyrolysis of onions skins was studied thoroughly for the first time. Kinetic calculations of devolatilization stages were performed applying direct Arrhenius plot (DAP) method and combinations of isoconversional and Criado's Z(α) master plot (CZMP) methods. The kinetic parameters calculated using combined methods were utilized successfully to reproduce the experimental kinetic curves whereas those calculated using DAP method failed in this sense. The average E_a values of isoconversional methods were between 164.0 and 172.0 kJ/mol. The CZMP method yielded multiple F-type reaction mechanisms. The simplified kinetic models of combined methods were also developed by using single reaction mechanisms deduced from multiple reaction mechanisms. The Friedman-CZMP combination was the best option for developing simplified/unsimplified kinetic models. Determination of reaction mechanism using DAP method by searching for the highest R² value of regression equation among several candidates was found unreliable. ΔH, ΔG and ΔS values were calculated for 10 °C/min heating rate.

Pyrolysis of mustard oil residue: A kinetic and thermodynamic study

Critical analysis of thermogravimetric data, characterization of the biomass, and kinetic and thermodynamic analyses are crucial in the design of efficient biomass pyrolysis systems. In this study, characterization, kinetic and thermodynamic analysis was performed for pyrolysis of mustard oil residue (MOR). Thermogravimetric analysis (TGA) with differential thermal analysis (DTA) was applied to study thermal decomposition behaviour of MOR at 10, 20, and 30 °C/min. FTIR and XRD analyses were used to characterize MOR. Average activation energy estimated from employed isoconversional methods was ≈155 kJ/mol. Variation in activation energy was found to be statistically insignificant as suggested by p-value of 0.992 by one-way ANOVA method. The pyrolytic temperature for MOR ranged from 234 to 417 °C. Reaction mechanism predicted as R3 (third order) and D3 (three dimensional). Thermodynamic parameters (ΔH_α, ΔG_α, and ΔS_α) showed that endothermicity increased from 0.2 to 0.8 conversion and product had highest energy at 0.8 conversion.