Master Plot Research Articles

Combustion kinetics and fuel performance of tackifying resins by TG-FTIR and DFT analysis

Combustion kinetics and fuel performance of tackifying resins such as glycerol ester of colophony (GEC), glycerol ester of hydrogenated colophony (GEHC), C9 petroleum resin (C9PR) and hydrogenated C9 petroleum resin (HC9PR) were studied. Non-isothermal thermal analysis was performed in an air atmosphere, and the combustion characteristic, kinetic and thermodynamic parameters were calculated. Results show that all the resins studied have good combustion performance and environmental characteristics, and their experimental calorific values are 1.15–1.54 times of standard coal-equivalent (29.31 MJ/kg), indicating that tackifying resins and their corresponding wastes are promising fuel for generating energy. Furthermore, based on the isoconversional and master plots methods, it was found that the combustion of different resins was a kinetically complicated reaction, but the R3 model had an acceptable fitting effect in the whole combustion process. TG-FTIR and density functional theory (DFT) results demonstrate that colophony-based resins tend to degrade/burn the branched chains first and then the tricyclic phenanthrene structures, while petroleum resins degrade/burn the CC bonds on the backbone first and then the aromatic compounds, and the volatiles are mainly composed of H2O, CH4, CO2, CO, aromatic compounds and carbonyl derivatives.

Pyrolysis characteristics, gas products, volatiles, and thermo–kinetics of industrial lignin via TG/DTG–FTIR/MS and in–situ Py–PI–TOF/MS

The lignosulfonates and de–alkalized lignin pyrolysis characteristics were evaluated by using TG/DTG–FTIR/MS and in–situ Py–PI–TOF/MS. TG/DTG experiments showed that lignin sample pyrolysis proceeded in three stages from 303.15 to 1173.15 K, and the thermographs shifted to higher temperatures with increasing heating rate. Gases MS analysis showed that the pyrolysis of sodium lignosulfonate produced more CH4 and CO2 than the pyrolysis products of calcium lignosulfonate and de–alkalized lignin. The escape temperature of volatile matter in the lignin samples were basically consistent with the order of its organic content, but there were obvious differences in product composition. The escape peak temperature of olefins, aromatics, monophenols, and bisphenols showed a decline trend with the increase of substituent carbon number. The sample pyrolysis thermo–kinetics was estimated by Coats–Redfern, FWO, KAS, and integral Master–plots methods. The activation energies were 66.74–678.20 kJ mol−1 (calcium lignosulfonate) > 32.24–598.38 kJ mol−1 (sodium lignosulfonate) > 44.27–265.69 kJ mol−1 (de–alkalized lignin). The most potential kinetic models were not all consistent with the standard curves for the stages of sample pyrolysis. This study provides theoretical and practical guidance for solving the engineering problems of lignin wastes pyrolysis in papermaking wastewater.

Study on pyrolysis of Organosolv lignin impregnated with alkali and alkaline earth metals: Kinetics, thermodynamics, and product characterization

The pyrolysis characteristics and kinetics of Organosolv lignin from pine trees were investigated using isoconventional, generalized master plot, model-based, and Frazer-Suzuki deconvolution methods. With these approaches, the activation energies of Organosolv lignin pyrolysis were determined to be in the range of 70.11–385.58 kJ/mol. In addition, the activation energies of 3 pseudo-reactions were calculated to be 15.71, 204.49, and 32.76 kJ/mol, respectively, by the Frazer-Suzuki deconvolution method. The experimental data of Organosolv lignin pyrolysis were best fitted with the 4th power-law model (P4) with an absolute error of 3.24 %. Entropy (ΔSo), Gibbs free energy (ΔGo), and enthalpy (ΔHo) were also calculated to understand the reaction pathways from a thermodynamic point of view. Based on the pyrolysis mechanisms proposed in this study, the reaction rate constants of different steps were determined. The primary reaction route was identified to be the pyrolysis of Organosolv lignin to liquid products such as bio-oils. Among the alkali and alkaline earth metals (AAEMs) tested, 2.0 wt% Mg showed the most effective on Organosolv lignin pyrolysis, decreasing the mean activation energy (Ea) from 181.67 to 156.55 kJ/mol in the range 0 ≤ X ≤ 0.85. The compositions of gaseous and liquid products formed by pyrolysis were analyzed using a micro-tubing reactor. CO, CO2, and CH4 were observed as the main gaseous products, while Organosolv lignin was primarily decomposed into phenol and guaiacol derivatives. The Organosolv lignin was also depolymerized into lower-molecular-weight (LMW) components during the pyrolysis process.

Hydrochar prepared from municipal sewage sludge as renewable fuels: Evaluation of its devolatilization performance, reaction mechanism, and thermodynamic property

Hydrothermal treatment (HT) of sewage sludge (SS) is a promising method to improve its dewaterability. Effect of HT on devolatilization performance, kinetic parameters, and thermodynamic property during the pyrolysis of SS was investigated by thermogravimetric analysis (TGA), isoconversional method, and master plots method. Derivative thermogravimetry (DTG) curves showed two distinct devolatilization peaks #1 at 283.21 °C and #2 at 327. 43 °C along with a shoulder between 400 and 600 °C. HT temperature influenced peak #2 more significantly as its peak devolatilization rate decreased consecutively from 4.25 % to 1.70 %∙min−1. Meanwhile it moved towards higher temperature and overlapped with the shoulder ultimately. The value of comprehensive pyrolysis index (CPI) decreased greatly from 3.37 × 10−5 to 1.24 × 10−6 %3∙°C−3∙min−2 with HT temperature. Activation energy was determined by Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Starink, and Friedman methods. It generally increased against conversion with diverse variation patterns. Its average value reduced obviously after HT. Despite HT, all samples followed identical Avrami-Erofeev model with decreased order of reaction from 7.60 to 6.56. The variation trends of enthalpy, Gibbs free energy, and entropy verified that HT improved the thermal stability of SS, which coincided with CPI. Pyrolysis process of SS evolved from ordered state to disordered state, indicating increased reactivity due to the probable catalytic effect of inorganics in the ash. The work provides guidance for the design, optimization, and upscale of pyrolysis reactors and operation parameters when SS is utilized as renewable fuels.

Non-isothermal nitridation kinetics of Ti6Al4V in Al2O3-based refractories

To establish a kinetic model of nitridation of Ti6Al4V in Al2O3-based refractories, the non-isothermal nitridation of Ti6Al4V–Al2O3 composite refractories at various heating rates was investigated using a thermogravimetric (TG) analyzer for large samples. The activation energy (E) and kinetic model (G(α)) for the nitridation of Ti6Al4V were determined using the isoconversional and master plots methods, respectively. The nucleation and growth of nitriding products of the TiN solid solution was the controlling step in the nitridation of Ti6Al4V in Al2O3-based refractories. The Avrami-Erofeev kinetic model, depicted by the G(α) = [-ln (1-α)]4 equation, is the most rational kinetic model. The values of E and A for the nitridation of Ti6Al4V were calculated to be 214.99 kJ/mol and 1.46 × 107 (S−1), respectively.

Effect ofCaSt2/ESOthermal stabilizers on the preparation, thermal stability, and thermal stability mechanism of self‐made vinylidene chloride‐methyl acrylate copolymer resin film

AbstractThe effects of heat stabilizer systems on the thermal stability and processability of self‐made vinylidene chloride‐methyl acrylate copolymer (PVDC‐MA) film were investigated via accelerated aging test, Congo red test, FTIR, DMA, and TG‐FTIR. These results displayed that CaSt2/ESO performed excellently in synergistic inhibition of PVDC‐MA thermal degradation. Especially, when the mass ratio of CaSt2/ESO was 1.5:1.5, the static thermal stability time of PVDC‐MA was increased from 14.5 to 46.5 min. The kinetic calculation results also verified this point. Compared with pure PVDC‐MA, the average apparent activation energy (Ēa) of thermal degradation reaction of PVDC‐MA stabilized by CaSt2/ESO enhanced from 144.1 to 169.7 kJ mol−1(α0 ≤ 0.1), indicating that the thermal stability of PVDC‐MA in the initial thermal degradation stage was dramatically improved by CaSt2/ESO. Moreover, the mechanism of the effect of CaSt2/ESO on PVDC‐MA in the initial thermal degradation stage was further explored by the generalized master plot methods. The kinetic analysis result suggested that under the synergistic effect of CaSt2/ESO, the mechanism model followed by the degradation of PVDC‐MA changed essentially (the three‐dimensional diffusion thermal degradation mechanism transformed into two‐dimensional diffusion).

Non-isothermal solid-state synthesis kinetics of the tetragonal barium titanate

The solid-state synthesis kinetics of the barium titanate is investigated through thermogravimetry analysis (TGA), and derivative thermogravimetry (DTG). The XRD results confirmed the formation of pure tetragonal BaTiO3 after thermal analysis. The thermodynamic parameters (ΔH,ΔS,ΔG) are calculated for all possible reactions involved during the formation of BaTiO3. The thermodynamic analysis predicted the formation of intermediate compounds (BaO, Ba2TiO4). The thermal kinetic analysis is also performed by using the deconvolution kinetic method. The thermal profile is convoluted in three peaks and the kinetic triplets are calculated. The activation energy is calculated by using the iso-conversional KAS kinetic model based on the Straink approximation. The order of the average activation energy is Peak III (225.81 ​kJ/mol) ​> ​Peak II (223.88 ​kJ/mol) ​> ​Peak I (197.67 ​kJ/mol). The reaction mechanism and pre-exponential are identified by the integral master plot method. The F1, R2 and A4 reaction mechanisms dominated the reaction occurring in peak I, peak II and peak III, respectively.

Insights on kinetic triplets and thermodynamic analysis of Delonix regia biomass pyrolysis

The aim of this work was to study the pyrolysis of Delonix regia biomass with non-isothermal thermogravimetric experiments. The targeted objective was to investigate kinetic triplets and thermodynamic parameters. Five iso-conversional methods, namely Differential Friedman, Kissinger-Akahira-Sunose, Ozawa-Flynn-Wall, Starink, and Distributed Activation Energy, have been considered. In the adopted heating rates of 5–55 °C min−1, the average activation energy and pre-exponential factor varied in the range 202.34–205.89 kJ mol−1 and 4.98 × 1017 – 2.04 × 1020 s−1 respectively. Corresponding average enthalpy and Gibbs free energy varied from 196.84 to 200.87 kJ mol−1 and from 182.64 to 206.41 kJ mol−1 respectively. Pyrolysis mechanism have been confirmed by Avrami-Erofeyev (A4), power-law (P2 and P4) and reaction (F1, F2, and ≥ F5) according to Criado's master plots.

Investigating transformation kinetics of yttrium hydroxide to yttrium oxide

The transformation kinetics involved during the formation of yttrium oxide through thermal dehydration of yttrium hydroxide was studied through differential thermal analysis (DTA) at multiple heating rates (1, 5, 7, 10 °C/min) in air. The yttrium hydroxide dehydrates in two steps to form yttrium oxide. The intermediate compound, i.e., YOOH was formed at 350 °C. The phase formation was confirmed through XRD and Le-Bail profile matching. FESEM confirms the dehydration of yttrium hydroxide and a rod-shaped microstructure was observed. An increase in temperature resulted in shrinkage of the rods. The kinetic triplets (activation energy, pre-exponential factor and reaction mechanism) were estimated for both the steps. The Straink method was used to evaluate activation energy, whereas the reaction mechanism was identified through the integral master plot method. The activation energy was 219.6 kJ/mol and 431.3 kJ/mol for step I and II of dehydration, respectively. Step I was dominated by the A2 reaction mechanism, while the F1 reaction mechanism was found in step II of yttrium hydroxide dehydration.

Thermogravimetric analysis of the torrefied Austrian pine

ABSTRACT This work investigated the impact of thermal pre-treatment on the thermal kinetics of pinecones. An improvised muffle furnace was used for the torrefaction process. The kinetic parameters for thermal decomposition of torrefied pinecones and the raw pinecones were determined from the isoconversional methods (Friedman, Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS)). The reaction mechanism (RM) of the raw and thermally processed pinecones was obtained by the Criado master plots. Thermogravimetric analyses of both the raw and thermally pre-treated pinecones were performed at a heating rate of 5°C·min−1, 10°C·min−1 and 15°C·min−1. Nitrogen gas was used as an inert medium for both thermal pre-treatment and pyrolysis of raw pinecones. The activation energies estimated from OFW and KAS, and Friedman for torrefied pinecones are 165.87 kJ·mol−1, 169.66 kJ·mol−1 and 130.68 kJ·mol−1,respectively. The calculated value of activation energy from OFW and KAS for the torrefied pinecones was estimated to be 8.66–8.93% higher than that of raw pinecones; however, in the case of the differential method, it decreased by a margin of 10%. The reduced reaction rate of the torrefied pinecones was slightly higher than that of the raw pinecones. However, no change in the characteristics of the reduced reaction rate of torrefied pinecones was noticed with respect to its raw form, in relation to thermal conversion. The clean gas generation after processing the raw pinecones was noticed to be 27.54% higher than its raw form. The weight percentages of alkali elements were increased by 24% after the torrefaction process.

Effects of CaO-Fe2O3-Fe3(PO4)2 in sewage sludge on combustion characteristics and kinetics of coal slime

The co-combustion of sewage sludge (SS) and coal slime (CS) is a promising approach to realize the harmless disposal of these two solid wastes. Aiming at the effects of the minerals in SS on CS combustion during the co-combustion, the combustion characteristics and kinetics of CS under the action of CaO, Fe2O3, and Fe3(PO4)2 were investigated by a thermogravimetric analyzer. The effects of the single and the composite minerals on CS combustion were quantified, and the synergistic or inhibitory effects between the minerals were also analyzed. Furthermore, Flynn-Wall-Ozawa (FWO) method and the master plots method were used to calculate the combustion kinetics. The results revealed that the catalysis of the minerals in SS was an important factor for the interaction between SS and CS during the co-combustion. For the single minerals, Fe2O3 exhibited the best catalytic effect, which reduced the ignition temperature (Ti) and burnout temperature (Tb) by 8.2 °C and 42.2 °C, respectively, and increased the comprehensive combustion characteristic index (S) by 10.7%. For the composite minerals, Fe2O3 and CaO synergistically catalyzed CS combustion through a cascade chain catalytic mechanism, resulting in a 15.9% increase in S compared with CS combustion alone. However, the interaction between Fe2O3 and Fe3(PO4)2 at high temperatures produced dense products that inhibit the burnout process. The kinetic results showed that the minerals in SS led to a decrease in the apparent activation energy of CS during the combustion stage of the fixed carbon, and the order of decreasing degree was Fe2O3 + CaO > Fe2O3 > Fe2O3 + CaO + Fe3(PO4)2. In addition, the combustion of CS was a multi-step kinetic process, and the mechanism function changed from f(α)= (1-α)4 to f(α)= (1-α) as the combustion progressed. The composite mineral Fe2O3 + CaO participated in the combustion reaction of fixed carbon in CS, changing the reaction mechanism from F1 to F1.3.

Catalytical enhancement on hydrogen production from LiAlH4 by Fe–Fe2O3 addition

Hydrogen storage technology plays an important role on the development of hydrogen fuel cell and lithium aluminum hydride is a powerful candidate for solid-state hydrogen storage materials. However, the high stability and slow dehydrogenation kinetics of LiAlH4 hinder its application. In this paper, the two-step thermal decomposition properties of LiAlH4 with and without Fe–Fe2O3 catalysts are investigated. According to the master plots, the model of mample power law (Pn) and nucleation and growth (An) are the optimal mechanism functions for the two-step decomposition of LiAlH4, respectively. After doping catalysts, the activation energies decrease significantly. The theoretical and optimized kinetic method are consistent with each other on activation energy. And the latter can also yield other kinetic parameters for a more comprehensive kinetic modelling of LiAlH4 decomposition. Furthermore, Fe–Al2O3 and Fe–Al intermetallics generated during dehydrogenation might significantly improve the hydrogen release properties of LiAlH4.

Investigation on prospective bioenergy from pyrolysis of butia seed waste using TGA-FTIR: Assessment of kinetic triplet, thermodynamic parameters and evolved volatiles

The pyrolysis of butia seed waste (BSW) was investigated under a thermogravimetric scale at multiples heating rates (5–40 °C min−1) in a nitrogen atmosphere. First, the pyrolysis behavior of BSW was deconvoluted into four independent reactions using the Asym2Sig fitting function. The kinetic triplets (activation energies, pre-exponential factors, and reaction models) were acquired using four isoconversional methods, the compensation effect method and the master plot method. The kinetic parameters estimated were in the range of 111.5–190.9 kJ mol−1 for the average activation energy and 1.55 × 1010–2.89 × 1014 min−1 for the pre-exponential factor. According to the master plot method, the pyrolysis of BSW is described by the summative effect of geometrical contraction and n-order reaction mechanisms. A multi-component kinetic approach was suitable for capturing the complexity involved in the pyrolysis of BSW, with a coefficient of determination (R2) > 0.95 and quality of fit (QOF) > 93%. Pyrolytic conversion of BSW into biofuels is characterized by an endothermic nature (ΔH > 0) and low reactivity (ΔS < 0). The volatile products evolved from the pyrolytic decomposition of BSW were characterized using the integrated TGA-FTIR system, which confirmed the presence of high-energy compounds (aromatics) and useful chemicals (aldehyde, ketone, esters, ether, and alcohols).

Reaction kinetics and thermodynamic analysis of non-isothermal co-pyrolysis of Delonix regia and tube waste

Non-isothermal co-pyrolysis of Delonix regia and tube waste was carried out using a thermogravimetric analyzer under nitrogen atmosphere at temperatures 25 to 1000 °C, with heating rates between 5 and 55 °C min−1. The kinetic triplets were estimated using five iso-conversional models: Differential Friedman, Kissinger-Akahira-Sunose, Ozawa-Flynn-Wall, Starink, and Distributed Activation Energy Method. In kinetic analysis, the average activation energy (Eα, kJ mol−1) and frequency factor (ko, min−1) values were 230.47 and 2.55× 1030; 208.13 and 8.31× 1026; 207.78 and 1.58× 1024; 208.38 and 6.47× 1026; 208.13 and 5.15× 1026; respectively. In thermodynamic analysis, average values of ΔH, (kJ mol−1), and ΔG, (kJ mol−1) were 225.38, 179.9; 225.28, 180.22; 225.18, 180.31; 225.08, 180.99; and 224.98, 182.15; respectively. Criado's master plot revealed a multistep reaction mechanism for the co-feed.

Evaluating the bioenergy potential of cupuassu shell through pyrolysis kinetics, thermodynamic parameters of activation, and evolved gas analysis with TG/FTIR technique

This research aimed to investigate the physicochemical properties and the pyrolysis performance of cupuassu shell (Theobroma grandiflorum) under a thermogravimetric scale. The pyrolysis experiments were carried out using a pure nitrogen atmosphere and at five heating rates (5, 10, 20, 30, and 40 K min−1). The pyrolysis kinetic triplet was calculated from the DTG thermograms using the isoconversional methods of Friedman, Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Starink combined with the compensation effect and master plots methods. TGA analyses revealed that cupuassu shell pyrolysis follows a devolatilization process of two steps: (1) represented by the two-dimensional diffusion-reaction model (D2), with average activation energies within 102.9–107.5 kJ mol−1, and (2) represented by the fourth-order reaction model (F4) with average activation energies within 176.7–243.0 kJ mol−1. Still, the pre-exponential factor value for the first kinetic stage (1.64×108 min−1) was lower than that of the second kinetic stage (3.19×1010 min−1). As verified, the kinetic triplets efficiently derived the global kinetic expression of cupuassu shell pyrolysis, reproducing reliable data on conversion rates. The evaluation of thermodynamic parameters of activation showed that cupuassu shell is viable biomass for pyrolysis applications, with values of ΔH≠ > 0, ΔG≠ > 0, and ΔS≠ < 0. The TGA-FTIR analysis showed that the evolved pyrolysis products were dominated by alcohols, aldehydes, ketones, organic acids, and aromatic/aliphatic hydrocarbons, supporting the utility of cupuassu shell as a potential source for bio-based chemicals production. In summary, the insights of this study validate the cupuassu shell as a prospective feedstock for producing bioenergy and bio-based chemicals, also bringing useful information for engineering purposes in the design or simulation of large-scale pyrolysis reactors.

Degradation mechanism and oxidation kinetics of C60 fullerene

Despite a great deal of research on the basic properties of C60 to the present, no detailed and comprehensive reports are available concerning its degradation mechanism and oxidation kinetics. However, a deeper understanding of the oxidation mechanism of the most common fullerene broadens the horizons of potential applications, especially at high temperatures. Therefore, this study attempted to investigate the fullerene oxidation process using kinetic analysis under non-isothermal conditions. Initially, the powder was structurally and morphologically characterized accurately via XRD, Raman spectroscopy, FESEM, and TEM analyses. This was followed by simultaneous thermal analysis (STA) (i.e., TG and DSC) at four different heating rates (2.5, 5, 10, and 15 °C min−1) in airflow, and kinetic analysis was subsequently conducted to evaluate the thermal oxidation of C60. The activation energy as evaluated by model-free methods turned out to be almost invariant within the specified range of reaction fraction (α). Model-fitting methods were also employed to identify the oxidation mechanism involved, from which emerged two models (i.e., R3 (g(α) = 1-(1-α)1/3) and F1 (g(α) = −ln(1-α))) as possible reaction mechanisms. However, further investigation using the Z(α) master plot method revealed that the kinetic model R3, a phase-boundary process, is the controlling mechanism of C60 oxidation with E ≈ 96 kJ mol−1 and lnA ≈ 9.1 min−1. Further examinations were conducted in the neutral atmosphere, and the partial oxidation process based on TEM and FESEM images revealed that oxygen and heat applied during the process play a central role in the deagglomeration of C60 particles and the consequent oxidation. In fact, considering the spherical morphology and the agglomerates present in the C60 powder, the contracting sphere kinetic model (R3) was found to capture the oxidation process due to attacks by the oxygen molecules at the interface of C60 powder agglomerates.

Pyrolysis of sulfuric acid-treated chrome-tanned leather wastes: Kinetics, mechanism and evolved gas analysis

Management and safe disposal of chrome-tanned leather wastes generated in leather industry are of great importance due to their potential health risks and environmental hazards. Herein, an integrated strategy was proposed for disposing of chrome-tanned leather scrap (CTLS). This method involves the separation of chromium salts from CTLS with sulfuric acid for recycling purpose, followed by pyrolysis of the acid-treated CTLS in an inert atmosphere. SEM/EDX analysis was employed to characterize the changes in composition and morphology of CTLS after acid treatment. CO2 and H2O are main pyrolysis gases of CTLS, while the acid treatment increases the relative content of aliphatic hydrocarbons and NH3 in evolved gases. The pyrolysis characteristics and kinetics of the acid-treated CTLS were investigated by thermogravimetric analysis (TGA) at three different heating rates. After 3 and 6 days of acid treatment, the average activation energy of CTLS (450.9 kJ/mol) obtained from the Flynn-Wall-Ozawa method decreased to 369.6 and 351.0 kJ/mol, respectively. It is assumed that the CTLS consists of two pseudocomponents: low-crosslinked collagen (LCol) and highly-crosslinked collagen (HCol). Using the generalized master plots method, random nucleation and nuclei growth model (An model) was found to be the most probable kinetic model for the pyrolysis process of LCol and HCol. The kinetic exponent for pseudocomponent pyrolysis varied between 3.00 and 3.90, and the pre-exponential factor ranged from 5.83 × 1012 to 2.93 × 1013 min−1. The results of the present study provide an alternative route and useful information for recycling and disposing of chrome-containing leather wastes.

Influence of water on thermo-oxidative behavior and kinetic triplets of shale oil during combustion

The oxidation reactions between oxygen and shale oil directly affect the feasibility and performance of air injection. In this work, the influence of water on thermo-oxidative behavior of shale oil was studied using high-pressure differential scanning calorimetry (HP-DSC). Subsequently, the kinetic triplets for shale oil oxidation in the absence and presence of water were determined using Friedman and Ozawa-Flynn-Wall (OFW) models as well as one advanced integral master plots method. The HP-DSC results showed that at 5 MPa, the shale oil was vulnerable to obviously higher heat release at the low-temperature oxidation (LTO) region compared to the high-temperature oxidation (HTO) region, resulting in shortening the oxidative induction time and achieving in-situ upgrading of shale oil. Water delayed the initial heat release due to the fact that heat release yielded by LTO compensated the heat adsorption yielded by evaporation of water and light hydrocarbons. Additionally, the heat release was reduced with the elevated water saturation as a result of the reduction in exothermic rates and intensified evaporation of water and light hydrocarbons. The higher energy was needed to trigger off the LTO reactions while increasing water saturation from 10% to 20%. Therefore, it was believed that the presence of water extended the oxidative induction time, thereby hindering the smooth and rapid transition from the LTO to HTO stages. Water changed the reactivity of each oxidation stage for shale oil, resulting in higher energy required for the initial LTO reactions and lower energy required for the subsequent oxidation reactions. The water saturation range of 10% to 15% could accelerate the occurrence of high-temperature combustion most effectively, demonstrated by values of activation energy for the conversion greater than 0.6. The appropriate oxidation reaction models for shale oil alone and water saturations of 10%, 15%, and 20% were determined to be D2, F1, F3, and R3, respectively. The determination of kinetic triplets assisted in building the reaction schemes for modelling the air injection process of shale oil reservoirs.

Co-pyrolysis of lignocellulosic biomass and plastics: A comprehensive study on pyrolysis kinetics and characteristics

Co-pyrolysis of biomass with plastics is an interesting research trend in improving both the yield and quality of oil products toward taking advantage of flexible material resources and sustainable fuel development. This study investigated the kinetic behaviors using thermogravimetric analysis and pyrolysis characterization for the co-pyrolysis of biomass (bamboo and oak wood) with plastics (polypropylene [PP] and polystyrene [PS]) in a fixed-bed reactor. The kinetic triplet for feedstocks was determined using the isoconversional method, compensation effect, and master plot method. The addition of 20 wt% plastics into biomass decreased the activation energy, with the most distinct positive synergistic effect for the bamboo/PS blend. In addition, the effect of co-pyrolysis temperature and biomass/plastic ratio on pyrolysis characteristics was investigated. Through biomass pyrolysis and biomass/plastic co-pyrolysis, the positive changes in distributions and physical-chemical properties of the products (i.e., char, oil, and gas) were observed using various analytical methods. Especially in the case of biomass/PS blends, the synergistic effect of co-pyrolysis was shown due to the difference in the actual and theoretical yields of the products. The liquid yields of the co-pyrolysis were 50.95, 50.17, 55.15, and 56.16 wt% for bamboo/PP, bamboo/PS, oak wood/PP, and oak wood/PS, respectively. The highest HHV of 28.22 MJ/kg was obtained for oil derived from the co-pyrolysis of bamboo/PS. Furthermore, co-pyrolysis chars have high HHVs in the range of 30.73–32.41 MJ/kg, suggesting that they can be used as solid fuels.

Thermal Degradation Kinetics Analysis of Ethylene-Propylene Copolymer and EP-1-Hexene Terpolymer.

LLDPE is a less crystalline polymer with vast industrial and domestic applications. It is imperative to understand the synthesis, processing conditions, and thermal degradation mechanism of the co- as well as terpolymers. This paper reports the in-situ synthesis and thermal degradation studies of the ethylene-propylene copolymer and ethylene-propylene-1-hexene terpolymer and its nanocomposite with ZnAL LDH sheets. The 1-hexene dosing during the in-situ process influenced the product yield and immensely affected the thermal stability of the resultant polymer. One milliliter 1-hexene in-situ addition increased the product yield by 170 percent, while the temperature at 10 percent weight loss in TGA was dropped by about 60 °C. While only 0.3 weight percent ZnAL LDH addition in the terpolymer improved the thermal stability by 10 °C. A master plot technique and combined kinetics analysis (CKA) were deployed to access the thermal degradation mechanism of the synthesized polymers.