Distribution Of Activation Energies Research Articles

The Gas Generation Process and Modeling of the Source Rock from the Yacheng Formation in the Yanan Depression, South China Sea

The research on deepwater oil and gas exploration areas is relatively limited, and sample collection is difficult. A drilled coal sample from Yanan Depression was used to investigate the hydrocarbon generation process, and the potential, by a gold tube thermal simulation experiment. The results show that the total gas yield was much higher than the oil yield. According to an analysis of the gas pyrolysis data, as represented by ln(C1/C2) and ln(C2/C3), the gas generation process consisted of two forms, namely, primary gas with ~1.33% Ro and secondary gas that occurred at levels greater than 1.33% Ro. The primary gas from kerogen was generated at ~1.33% Ro, which coincided with the %Ro value of the maximum oil yield. The activation energy distribution of the C1–C5 generation processes ranged from 54 to 72 kcal/mol, with a frequency factor of 6.686 × 1014 s−1 for the coal sample. We constructed the history of gas generation on the basis of the process and kinetic parameters, combined with data on the sedimentary burial and thermal history. The extrapolation of the gas history revealed that the gas has been generated from 5 Ma to the present, with a maximum yield of 178.5 mg/gTOC. This history suggests that the coal has good primary gas generation potential and provides favorable gas source conditions for the formation of gas fields. This study provides a favorable basis for expanding the effective source rock areas.

Systematical analysis and application of distributed activation energy model (DAEM) with Weibull distribution for pyrolysis kinetics of lignocellulosic biomass

The distributed activation energy model (DAEM) is a comprehensive and accurate kinetic model for describing the thermal decomposition kinetics of complex materials. The Gaussian distribution is commonly used for representing the activation energy distribution, however, it is symmetric and cannot reflect the reactivity asymmetry involved in complex chemical kinetics. The Weibull distribution offers an alternative to represent the distribution of activation energies. This study performed a systematical investigation of the DAEM with Weibull distribution, focusing particularly on its asymmetric characteristics. Additionally, the DAEM with Weibull distribution was applied to analyze the pyrolysis kinetics of rice straw and cotton stalk. The theoretical analysis results showed that the DAEM with Weibull distribution could provide abundant flexibility to elucidate the asymmetric reactivity of complex chemical kinetics. The pyrolysis processes of rice straw and cotton stalk could be deconvoluted into several sub-processes, which could be accurately described by the DAEMs with Weibull distribution. The obtained Weibull distributions of activation energies for those deconvoluted sub-processes validated their asymmetric reactivities. It is expected that the results could help in exploring the kinetic mechanisms of lignocellulosic biomass pyrolysis and facilitate the application of the DAEM with Weibull distribution in analyzing complex chemical kinetics.

Elucidating Kinetic Mechanisms of Lignin and Biomass Pyrolysis by Distributed Activation Energy Model with Genetic Algorithm

Elucidating Kinetic Mechanisms of Lignin and Biomass Pyrolysis by Distributed Activation Energy Model with Genetic Algorithm

Applicability of genetic algorithm in biochar combustion kinetics with double distributed activation energy model

Applicability of genetic algorithm in biochar combustion kinetics with double distributed activation energy model

Pseudo Master Curve Analysis of an Infinite Number of Parallel First-Order Reactions: Improved Distributed Activation Energy Model.

The so-called Distributed Activation Energy Model (DAEM) has been used extensively, mainly to analyze pyrolysis reactions of solid reactants. The model expresses many parallel first-order reactions using the distributions of activation energy f(E) and frequency factor k 0(E). Miura and Maki presented a method to estimate both f(E) and k 0(E) in the DAEM in 1998. This model has been used successfully by many researchers. In this paper more general basic equations are derived for describing an infinite number of parallel first-order reactions by extending the basic equations for the finite number of parallel first-order reactions. Revisiting the Miura-Maki method based on the general basic equations, a graphical analysis method that may be called "Pseudo Master Curve Analysis" is presented. The method not only supplements the Miura-Maki method but gives the underlying concept of the Miura-Maki method clearly. It is also shown that the graphical method can be applicable to analyze single reactions and the experimental data obtained using isothermal reaction techniques. Next, a method that improves the estimation accuracy of k 0(E) is presented. Practical examples analyzing several experimental data are also given to show the usefulness and validity of the Miura-Maki method and the graphical method. Through the examination, it is proposed that the DAEM should be renamed, for example, as the Distributed Rate Constant Model (DRCM).

Transport and Kinetic Property of the Butyric Acid in Water: A Simulation Study

Microbiota is defined as a class of all microorganisms which includes fungi, protozoa, bacteria and viruses. About 90 % of all microbiota in our body are found in our gut that regulates host immunity. The gut-brain axis is a bidirectional communication system that allows gut microbiota to communicate with the brain and vice versa. Studies suggest that the gut dysbiosis may enhance neurotoxic substances such as short-chain fatty-acids (SCFAs which are acetate, propionate, and butyrate) to the blood circulation and even to the brain through damaged blood brain barrier (BBB) and may cause protein aggregation which are implicated in the pathogenesis of several neurodegenerative diseases like Alzheimer’s disease (AD), Parkinson’s disease (PD), prion disease, motor neuron disease, Huntington’s disease (HD), Amyotrophic lateral sclerosis (ALS). Specifically, butyric acid are the main SCFA product that may impact on gut health. Therefore, this article aims to investigate the transport and kinetic properties such as diffusion coefficient, activation energy and radial distribution function of butyric acid in water at different temperatures through molecular dynamics simulations. The self and binary diffusion coefficient of butyric acid in water obtained from our MD simulation are found to be 0.8699×10−9m2s−1 and 0.8714×10−9m2s−1, respectively at 300 K and the activation energy for self-diffusion coefficient of water estimated from the slope of ln(D) versus 1/T is equal to 16.07 kJ/mol. Our results are in accordance with those obtained from the experimental values. This study offers an alternate approach to researching the diffusion of butyric acid in living organisms. This knowledge contributes to advancements in various fields, including nutrition, gastroenterology, microbiology, and pharmacology.

CO2 hydrogenation to methanol over Pt functionalized Hf-UiO-67 versus Zr-UiO-67.

Sustainable methanol formation from CO2/H2 is potentially a key process in the post-fossil chemical industry. In this study, Hf- and Zr-based metal-organic framework (MOF) materials with UiO-67 topology, functionalized with Pt nanoparticles, have been tested for CO2 hydrogenation at 30 bar and 170-240°C. The highest methanol formation rate, 14 molmethanol molPt-1 h-1, was obtained over a Hf-based catalyst, compared with the maximum of 6.2 molmethanol molPt-1 h-1 for the best Zr-based analogue. However, changing the node metal did not significantly affect product distribution or apparent activation energy for methanol formation (44-52 kJ mol-1), strongly indicating that the higher activity of the Hf-based analogues is associated with a higher number of active sites. Both catalysts showed stable catalytic performance during testing under kinetic conditions, but the addition of 2 vol% water to the feed induced catalyst deactivation, in particular the Hf-MOFs. Interestingly, mainly methanol and methane formation rates decreased, while CO formation rates were less affected by deactivation. No direct correlation was found between catalytic stability and framework stability (crystallinity, specific surface area). Experimental and computational studies suggest that water adsorption strength to the MOF node may affect the relative catalytic stability of Hf-UiO-67-Pt versus Zr-UiO-67-Pt methanol catalysts.This article is part of the discussion meeting issue 'Green carbon for the chemical industry of the future'.

Kinetic characteristics and product distribution of tar-rich coal in-situ underground pyrolysis: Influence of heterogeneous coal seam

Tar-rich coal contains more hydrogen-rich structures such as aliphatic side chains and bridge bonds, which is a good raw material for coal to oil. In-situ underground pyrolysis of tar-rich coal has significant advantages such as environmental friendliness and high safety factor; it is an efficient, clean coal utilization technology. Due to the influence of geological structure and other factors in the formation process, underground coal seam was often heterogeneous, generally accompanied by coal gangue interlayers. Due to the coal gangue being relatively dense and has poor thermal conductivity, it is also rich in metal oxides, it would inevitably affect the pyrolysis characteristics and product distribution during the pyrolysis process of heterogeneous tar-rich coal seam. The pyrolysis characteristics of heterogeneous tar-rich coal seam with different positions and layers of coal gangue interlayer were investigated by the thermogravimetric analyzer, and related kinetic parameters were obtained by the distributed activation energy model (DAEM). Based on the fixed bed tube furnace reactor, the pyrolysis experiments of heterogeneous tar-rich coal seam with different positions and layers of coal gangue interlayer were also carried out, and the pyrolysis products were characterized and analyzed. The thermogravimetric results showed that in the pyrolysis process of heterogeneous tar-rich coal seam, the initial pyrolysis temperature and the temperature corresponding to the maximum weight loss rate shifted to the higher temperature range, and the pyrolysis characteristic index decreased significantly. Under the same conditions, the corresponding pyrolysis characteristic indexes of the upper coal gangue interlayer and 4 layers of coal gangue interlayer were lower, which were 11.69 (10−8·%·min−1·℃−3) and 11.65 (10−8·%·min−1·℃−3), respectively. Compared with homogeneous tar-rich coal seam, pyrolysis activation energies of heterogeneous coal seam generally showed the decreasing trend. Under the conditions of the upper part containing coal gangue interlayer and the upper-and-lower parts containing coal gangue interlayer, the pyrolysis activation energies were higher due to the hindrance of the cover layer of coal gangue to the volatile release, which were 555.88 kJ·mol−1 and 546.66 kJ·mol−1 respectively. The results of fixed bed pyrolysis experiments showed that compared with homogeneous tar-rich coal seam, the tar yield obtained was reduced, the degree of tar lightening was significantly improved, and the proportion of lighter tar was up to 70.00 wt%. The contents of aromatic hydrocarbons and phenolic compounds in tar increased, the contents of aliphatic hydrocarbons and oxygenated compounds decreased significantly, and the maximum reductions were nearly 4.50 wt% and 6.50 wt%, respectively. The gas yield increased, the proportions of H2 and CO2 in the gas increased, and the proportions of CO and CH4 decreased to varying degrees. The tar yields were lower under the conditions of upper gangue and 4 layers gangue, which were 6.53 wt% and 5.81 wt%, respectively, and the degrees of tar lightening were also more significant. From the relationship between pyrolysis characteristic parameters and tar properties of heterogeneous tar-rich coal seam pyrolysis, it was found that the existence of coal gangue interlayer was not conducive to the tar production, but it could promote the lightening of tar and improve the tar quality. Exploring the kinetic characteristics and pyrolysis product distribution of heterogeneous tar-rich coal seam could provide theoretical guidance for the site selection of in-situ underground pyrolysis engineering and the well arrangement.

Petroleum source-rock characterization and the depositional environment of Kimmeridgian–Tithonian sequences, Jaisalmer Basin, western Rajasthan, India

In hydrocarbon exploration, total organic carbon (TOC) content and Rock-Eval pyrolysis are commonly employed geochemical techniques that offer concise insights into kerogen type, effective source-rock identification and thermal maturity. In the current study, the data obtained from Rock-Eval pyrolysis has been used to define the source-rock quality, generative potential, kerogen type, maturity of the source sediments and kerogen kinetics of the Baisakhi–Bhadesar Formation of Kimmeridgian–Tithonian (154.7–145.6 Ma) age. Basinal level hydrogen index (HI), TOC content, source-rock maturity, transformation ratio and heat-flow maps have been generated by integrating the data from pyrolysis with previously available data from wells drilled in the basin. The TOC content of the Kimmeridgian–Tithonian sequence ranges from 0.03 to 12.71% in the studied samples, with an average TOC content of 1.28%, indicating good source-rock quality. The HI, in collaboration with T max and vitrinite reflectance (VR o ) data, demonstrates that the Baisakhi–Bhadesar Formation is characterized by type II, a mixture of type II/III and type III kerogen facies and exhibits good source-rock quality and poor to good generative potential in the basin. The studied samples are marginally mature to mature in nature ( T max , 430–450°C; VR o , 0.52–0.72%). A maturity analysis of the basin suggests that during the Late Jurassic most areas were under the oil window zone, except for the Bhakhari Tibba and Miajlar areas. The transformation ratio overlay for the Kimmeridgian–Tithonian source sequences shows better transformations of the source rock in the area of the Shagarh Sub-basin. Kerogen kinetics of the studied Baisakhi–Bhadesar Formation demonstrate that the activation energy ranges between 46 and 74 kcal mol −1 with the significant distribution of activation energy being 54 kcal mol −1 (42.07%), representing a strong heterogeneous type of organic matter in the sediments. Based on lithological, palaeontological and electrolog studies, a shallow-marine to nearshore environment of deposition with a sediment-input direction from the SE has been inferred for the Kimmeridgian–Tithonian sequences. The results of this study quantitatively establish the role of the Kimmeridgian–Tithonian sequence as a source rock, ultimately contributing to the generation of hydrocarbons in the basin along with spatial changes in the quality of source sediments in different parts of the basin.

Experimental and kinetic study of PET pyrolysis under fast and slow heating rates using a visualized Macro TGA

A visualized macro thermogravimetric analyzer was utilized to gather data on sample weight, temperature, and image signals of centimeter-scale PET. The PET was subjected to both fast (above 300 K/min) and slow (below 25 K/min) heating rates. The experimental findings revealed that weight loss mainly occurred at different temperature ranges under fast (above 610 °C) and slow (400–520 °C) heating rates. The isoconversional method (ICM) and the distributed activation energy model (DAEM), both assuming single-step reactions, were employed separately to predict the conversion and rate of PET pyrolysis. However, the prediction error was considerable. To address this issue, a discrete distributed activation energy model (DDAEM) was developed, incorporating both single-step and double-step parallel reactions. The DDAEM yielded a prediction error within 10 %, which is better than ICM and DDAEM. Furthermore, all three models (ICM, DAEM, and DDAEM) indicated significant discrepancies in activation energies between fast and slow heating rates.

Investigation of the co-pyrolysis characteristics and gas emission properties of spent bleaching earth and biomass in a thermogravimetric analyser and a fixed bed reactor

The co-pyrolysis of spent bleaching earth (SBE) for adsorption decolorization and biomass can promote the resource utilization of industrial waste. The thermal behaviour and kinetics during the co-pyrolysis of SBE with sawdust (SD) were comparatively evaluated with thermogravimetric analysis at different mixing ratios and heat rates. Activation energies corresponding to the different conversion rates were determined by the distributed activation energy model (DAEM). The pyrolysis yield and evolved gases were measured by a fixed bed pyrolysis system. The results demonstrated that as SBE increased, the activation energy during the initial stage of pyrolysis clearly decreased. The fixed bed isothermal pyrolysis experiment showed that the increase in SBE had a significant effect on the gas production components, resulting in a decrease in CO and CO2 yields and an increase in alkane content. At 800°C, the addition of 30 % SBE had the highest H2 yield, indicating that SBE is a valuable additive.

Unlocking biosolid pyrolysis: Towards tailored biochar with different surface properties

To develop a thorough understanding of the thermal decomposition process of biosolids and the qualities of biosolid-derived biochar, this study performs a thermogravimetric analysis (TGA) of biosolids and examines the properties of biosolid-derived biochar produced from varying temperatures of pyrolysis. The pyrolysis of biosolid is conducted under varying heating rates (10, 15, 20 and 25 °C/min) until reaching the maximum temperature of 900 °C. The kinetic triplet (kinetic model, activation energy, and frequency factor) at the corresponding conversion point is determined by analysing the TGA results of the biosolids. The thermal degradation of hydrated compounds shows activation energies ranging from 80 to 100 kJ/mol, whereas the thermal decomposition of organic matter in biosolids exhibits activation energies ranging from 120 to 497 kJ/mol. As the temperature increases, the thermal reactions transition from simple surface reactions with frequency factors below 109 s−1 to more complex reactions with frequency factors above 109 s−1. The distributed activation energy model (DAEM) is established using the approximated temperature function and the activation energy distribution functions. The DAEM shows the mean activation energies of 93–128 kJ/mol, 279–287 kJ/mol and 359–377 kJ/mol for activation energy distribution peaks. The standard deviations of the mean activation energies are 30–64 kJ/mol, 23–30 kJ/mol and 23–41 kJ/mol, respectively. As the pyrolysis temperature is raised from 700 °C to 900 °C, both the specific surface area and micropore volume of biosolid-derived biochar increase, from 48.25 m2/g to 65.74 m2/g and 0.0313 cm3/g to 0.0369 cm3/g, respectively. The findings of this study demonstrate biosolid pyrolysis kinetics, which is essential for establishing a pyrolysis facility for biosolid management and producing biosolid-derived biochar with varying qualities.

Non‐isothermal Thermogravimetric Analysis of Peltophorum pterocarpum and Evaluation of Kinetic Triplet

AbstractThe primary focus of the twenty‐first century has been on developing new and cleaner fuels from renewable sources. The increasing availability of renewable energy sources in environment, such as lignocellulosic biomass derived from agricultural and forest residues, has created a plethora of opportunities for biofuel production. For this purpose, the search for appropriate waste biomass source and the design of suitable reactors are very essential, where the latter requires the knowledge of kinetic triplets. These requirements paved the way to the novelty of the present work as a selection of a rarely used biomass source, that is, Peltophorum pterocarpum, and its non‐isothermal thermogravimetric analysis for the evaluation of kinetic triplet of the process. The range of temperature is 298–1173 K attained at heating rates of 10–55 K min−1. Kinetics were estimated using differential Friedman method (DFM), distributed activation energy method (DAEM), Ozawa–Flynn–Wall (OFW), Kissinger–Akahira–Sunose (KAS), and Starink (STK) models. Mean activation energy (kJ mol−1) and pre‐exponential factor (min−1) of pyrolysis process by five models were 183.68 and 1.24 × 1017 for DAEM, 194.28 and 3.08 × 1021 for DFM, 183.68 and 4.40 × 1016 for KAS, 184.12 and 2.12 × 1014 for OFW, and 183.93 and 3.56 × 1016 for STK. Average values of changes in Gibbs free energy, enthalpy, and entropy by five models are 174 kJ mol−1, 178 kJ mol−1, and 0.007 kJ mol−1 K−1, respectively. Criado's master plots revealed distinct reaction pathways during the process for different conversion levels.

Demineralization effects on physicochemical and combustion characteristics of biomass: Insights into distributed kinetics, flue gas evolution, and slag formation

Biomass as the only carbon-bearing renewable energy has enormous potential to challenge the established energy structure dominated by fossil resources, and incineration technology is one of the most direct and efficient pathways for utilizing biomass resources, unfortunately enduring the inevitable sintering and slagging problems owing to the excessive alkali metals. Herein, we comparatively investigated the effects of five leaching solvents (water, acetic acid, wood vinegar, hydrochloric acid, and oxalic acid) on the physicochemical properties and ash-removal capabilities of wheat straw (WS) and rice husk (RH), with a view to achieving better performance in the subsequent combustion characteristics, kinetic examination, flue gas, and slag evolution. Results indicated with ionization ability increased (water < acetic acid < hydrochloric acid), the WS exhibited a strong demineralization performance (maximum 61.1%), further leading to a steep weight loss in its combustion characteristic curve at approximately 350 °C and a delayed peak temperature after the removal of alkali metal. Multiple distributed activation energy model and sensitivity analysis revealed that leaching pretreatment enhanced the activation energy (189–191.8 kJ mol−1) and optimized energy distribution at the preliminary stage of the combustion reaction. In addition, the absence of alkali metals suppressed the catalytic oxidation reaction in the flue gas, remarkably limiting the formation of CO2 but facilitating the release of CO and CH4. Meanwhile, a considerable optimal in biomass ash slagging, in which the initial temperature of the liquid phase slag for WS ash increased to 991 °C. Notably, HCl showed the strongest demineralization performance among the five leaching solvents during pretreatment, but the high-temperature slag content was still higher than that of acetic acid. Therefore, slagging performance is not only associated with the demineralization ability of leaching solvents, but also with ash composition.

KINETICS AND THERMODYNAMIC ASSESSMENT OF RICE HUSK IN AN INERT ATMOSPHERE AS A FEEDSTOCK FOR ALTERNATIVE FUEL PRODUCTION

The utilisation of rice husk as a feedstock for alternative fuel production is an area of growing interest due to its abundance and potential as a renewable energy source. This study reports investigation of kinetics and thermodynamics of rice husk pyrolysis in an inert atmosphere. Experimental analysis, including proximate, ultimate, structural composition and thermogravimetric analyses (TGA), were conducted to determine the proxanal, ultanal, chemical composition and pyrolysis characteristics of rice husk under inert conditions. Kinetics of the pyrolysis process was evaluated using distributed activation energy model (DAEM) while thermodynamic parameters such as activation energy (E A), changes in enthalpy (ΔH), entropy (ΔS),and Gibbs free energy (ΔG) were computed to provide insights into the reaction mechanisms. The feedstock exhibited ash content, fixed carbon, volatile matter, and higher heating value on dry basis of 13.56wt%, 16.37wt%, 70.07wt% and 15.22MJ/kg respectively while the result of ultimate analysis showed carbon, hydrogen, nitrogen, sulphur and oxygen content of 40.95, 5.67, 0.22, 0.09 and 52.17wt%. The chemical composition result (water extractives-free) indicated cellulose, hemicellulos and lignin content of 39.12, 17.56 and 22.43 wt%. The kinetics analysis revealed that the pyrolysis process followed a single-order reaction mechanism and irreversible, suggesting that the pyrolysis reactions proceed in a direction that favors the formation of products. The average E A, ΔH, ΔS and ΔG required for the pyrolysis reactions was established to be 140.56 kJ/mol, 137.00 kJ/mol, -135.25 J/mol and 222.38 kJ/mol respectively. The comprehensive assessment of the feedstock affirms its suitability for alternative fuel production towards a greener energy landscape.

Distributed activation energy treatment of polyimide aerogel and its blocking effect on thermal runaway propagation of ternary battery

The thermal runaway of lithium batteries has become an urgent problem that needs to be solved today. In this study, polyimide aerogel materials with high temperature resistance and low thermal conductivity were prepared by supercritical drying equipment. Firstly, the activation energy distribution of the two pseudo-components of polyimide aerogels was calculated by TGA data at different heating rates, and then the optimal kinetic parameters were obtained. Secondly, a series of experiments were designed to study the blocking effect of polyimide aerogel films with different thicknesses (0.5 mm, 1 mm, 1.5 mm, and 2 mm) on the uncontrolled transmission of batteries, which showed that 2 mm film could successfully block the uncontrolled transmission of battery heat at 711.9 °C. 0.5 mm, 1 mm and 1.5 mm polyimide aerogel films can delay the thermal runaway of the battery, and the delay time was 182 s, 224 s and 259 s respectively. At the same time, the indicator gas was detected and analyzed, indicating that the barrier material can effectively reduce the content of CO2 gas and heat release rate. This study provides new enlightenment for the development of polyimide aerogels, and new ideas for the thermal insulation design of batteries.

Withdrawn: Co-hydropyrolysis of sewage sludge and algae biomass: A systematic study on thermal decomposition behaviors and kinetic characteristics

In the present study, a thermogravimetric analyzer was used to assess the co-hydropyrolysis kinetics of sewage sludge and algae biomass. Three isoconversional methods (Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, and Friedman) and one model-fitting method (DAEM) accurately fitted the experimental data at three heating rates (10, 30 and 50 °C/min) between 10 % and 90 % conversion. These methods agree with the trends shown by the activation energy (Ea) distribution calculated, with fluctuations between 120 and 330 kJ/mol. Compared with the pyrolysis of a single sample, the reaction activation energy of sludge and algae was significantly reduced in the case of co-pyrolysis. When 20 % algae are added, the activation energy is only 50 % of the original, below 100KJ/mol. Physiochemical characterization confirmed that they have the potential for fuel and energy production. Kinetic parameters fitted by DAEM were successfully verified at the highest heating rate studied and the linear fitting curve of DAEM is better. The kinetic results confirm that the activation energy is related to the conversion rate, and the change of activation energy and conversion rate indicates that the biomass undergoes a very complex pyrolysis process. In this study, the mixing of sewage sludge and algal biomass in hydrogen atmosphere can significantly change the energy required for pyrolysis reaction, which provides data support for the development, design and optimization of pyrolysis reactors. According to the change of weight loss and activation energy, it provides support for the feed amount, reaction temperature and gas flow of the pyrolysis furnace in the process of pyrolysis reaction.

Comprehensive investigation of almond shells pyrolysis using advance predictive models

This research focused on comprehensive characterization and assessment of almond shells pyrolysis for bioenergy potential through thermogravimetric analysis from ambient temperature to 900 °C at different heating rates of 10, 15, and 20 °C/min in inert environment. Iso-conversional model-free methods like Friedman, Ozawa-Flynn-Wall (OFW), and Kissinger-Akahira-Sunose (KAS) were used for kinetic analysis. Average activation energies (Ea) evaluated using Friedman, OFW, and KAS methods were 198.45 kJ mol−1, 204.43 kJ mol−1, and 204.97 kJ mol−1, respectively. The evaluation of thermodynamic parameters, including ΔH‡, ΔG‡, and ΔS‡, was also assessed. The average values of ΔH‡, ΔG‡, and ΔS‡, were found to be 199.4 kJ mol−1, 172.17 kJ mol−1 and 42.60 kJ mol−1 respectively. The reaction mechanism was obtained from combined kinetics. A high R2 value of 0.9933 demonstrates strong agreement between the combined kinetic analysis results and the experimental data. The distribution activation energy model was assessed employing four pseudo elements identified as PC1, PC2, PC3, and PC4. Artificial Neural Network (ANN) and Boosting regression trees (BRT) were used for the prediction of Ea of almond shells pyrolysis. The detailed understanding of thermokinetics and creating customized predictive and innovative modelling techniques like ANN and BRT sets a new benchmark for developing customized models for thermochemical conversion of varieties of almond shells.

Lifespan prediction procedure of volume nanogratings imprinted by femtosecond laser in optical glasses

Volume nanogratings imprinted by infrared femtosecond laser in oxide glasses exhibit a characteristic birefringent signature, which translates into measurable retardance. Upon thermal annealing, such signature is progressively erased, typical of nanograting erasure. In this work, we propose a procedure to predict the lifespan of nanogratings by two main approaches: 1/ numerical modeling of optical retardance ageing using the Rayleigh-Plesset equation, and 2/exploiting VAREPA (VAriable REaction PAthways) framework fed by simulated ageing data. By considering experimental time – temperature annealing conditions, the modeled retardance is gathered as a function of demarcation energy to build a so-called Master Curve and then compared to accelerated ageing experiments. The erasure constant rate k0 can be determined for 8 commercial optical glasses. Based on a distributed Rayleigh-Plesset model, k0 and activation energy distribution are linked to glass viscosity and its temperature dependency. Finally, we discussed the restrictions on VAREPA application for an accurate lifetime prediction. This work provides guidelines for the future development of nanogratings based devices and applications, including optical data storage, birefringent devices, and optical sensors, through a judicious choice of glass composition and associated properties.

Comprehensive kinetic modeling and product distribution for pyrolysis of pulp and paper mill sludge

Pyrolysis holds immense potential for clean treatment of pulp and paper mill sludge (PPMS), enabling efficient energy and chemical recovery. However, current understanding of PPMS pyrolysis kinetics and product characteristics remains incomplete. This study conducted detailed modeling of pyrolysis kinetics for two typical PPMSs from a wastepaper pulp and paper mill, namely, deinking sludge (PPMS-DS) and sewage sludge (PPMS-SS), and analyzed comprehensively pyrolysis products. The results show that apparent activation energy of PPMS-DS (169.25–226.82 kJ/mol) and PPMS-SS (189.29–411.21 kJ/mol) pyrolysis undergoes significant change, with numerous parallel reactions present. A distributed activation energy model with dual logistic distributions proves to be suitable for modeling thermal decomposition kinetics of both PPMS-DS and PPMS-SS, with coefficient of determination >0.999 and relative root mean square error <1.99 %. High temperature promotes decomposition of solid organic materials in PPMS, and maximum tar yield for both PPMS-DS (53.90 wt%, daf) and PPMS-SS (56.48 wt%, daf) is achieved at around 500 °C. Higher levels of styrene (24.45 % for PPMS-DS and 14.71 % for PPMS-SS) and ethylbenzene (8.61 % for PPMS-DS and 8.33 % for PPMS-SS) are detected in tar and could be used as chemicals. This work shows great potential to propel development of PPMS pyrolysis technology, enabling green and sustainable production in pulp and paper industry.