Conversion Range Research Articles

Thermo-kinetic behaviour of green synthesized nanomaterial enhanced organic phase change material: Model fitting approach

Metal, carbon and conducting polymer nanoparticles are blended with organic phase change materials (PCMs) to enhance the thermal conductivity, heat storage ability, thermal stability and optical property. However, the existing nanoparticle are expensive and need to be handle with high caution during operation as well during disposal owing to its toxicity. Subsequently handling of solid waste and the disposal of organic PCM after longevity usage are of utmost concern and are less exposed. Henceforth, the current research presents a new dimension of exploration by green synthesized nanoparticles from a thorny shrub of an invasive weed named Prosopis Juliflora (PJ) which is a agro based solid waste. Subsequently, the research is indented to decide the concentration of green synthesized nanoparticle for effective heat transfer rate of organic PCM (Tm = 35–40 °C & Hm = 145 J/g). Furthermore, an in-depth understanding on the kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM after usage via Coats and Redfern technique is exhibited. Engaging a two-step method, we fuse the green synthesized nanomaterial with PCM to obtain nanocomposite PCM. On experimental evaluation, thermal conductivity of the developed nanocomposite (PCM + PJ) increases by 63.8% (0.282 W/m⋅K to 0.462 W/m⋅K) with 0.8 wt% green synthesized nanomaterial owing to the uniform distribution of nanoparticle within PCM matrix thereby contributing to bridging thermal networks. Subsequently, PCM and PCM + PJ nanocomposites are tested using thermogravimetric analyzer at different heating rates (05 °C/min; 10 °C/min; 15 °C/min & 20 °C/min) to analyze the decomposition kinetic reaction. The kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM and its nanocomposite of PCM + PJ provides insight on thermal parameters to be considered on large scale operation and to understand the complex nature of the chemical reactions. Adopting thirteen different chemical mechanism model under Coats and Redfern method we determine the reaction mechanism; kinetic parameter like activation energy (Ea) & pre-exponential factor (A) and thermodynamic parameter like change in enthalpy (ΔH), change in Gibbs free energy (ΔG) and change in entropy (ΔS). Dispersion of PJ nanomaterial with PCM reduces Ea from 370.82 kJ/mol−1 to 342.54 kJ/mol−1 (7.7% reduction), as the developed nanomaterial is enriched in carbon element and exhibits a catalytic effect for breakdown reaction. Corresponding, value of ΔG for PCM and PCM + PJ sample within heating rates of 05–20 °C/min varies between 168.95 and 41.611 kJ/mol−1. The current research will unbolt new works with focus on exploring the pyrolysis behaviour of phase change materials and its nanocomposite used for energy storage applications. This work also provides insights on the disposal of PCM which is an organic solid waste. The thermo-kinetic profile will help to investigate and predict the optimum heating rate and temperature range for conversion of micro-scale pyrolysis to commercial scale process.

Solution polymerization mechanisms and kinetics of bismaleimide with trithiocyanuric acid

Solution polymerization mechanisms and kinetics of 4,4′-bismaleimidodiphenylmethane (BMI) with trithiocyanuric acid (TCA) in n-methyl-2-pyrrolidone (NMP) were investigated. A competition between the aza-Michael addition reaction and free radical polymerization occurred, and the reaction system competed with the predominant aza-Michael addition reaction. Model-free in differential form method was used to determine activation energy along fractional conversion. In addition, the model-fitting approach was adopted to assess compensation effect parameters for the activation energy and pre-exponential factor. Then, triplet kinetic parameters were achieved. The average activation energy and frequency factor were approx. 94 kJ mol−1 and 1.45 × 1012 min−1, respectively, in the fractional conversion (α) range 0.1–0.9, and the reaction-order model, f(α) = (1 − α)0.81, was of choice. Importantly, these triplet kinetic parameters could effectively predict kinetic curves for the isothermal reaction BMI and TCA.

Phase behavior and GOR evolution using a natural maturity series of lacustrine oil-prone shale: Implications from compositional modelling

For the exploration of shale oil, there is still an urgent need to relate hydrocarbon generation reactions and changing phase behavior to exact levels of thermal maturity. Six organic-rich shale samples from the Cretaceous Qingshankou Formation, Songliao Basin spanning the maturity range with vitrinite reflectance (Ro) 0.58%–1.16% were studied for petroleum generation characteristics using the PhaseKinetics, PhaseSnapshot, and GORFit approaches. All samples show very good petroleum potential and contain Type I kerogen with total organic carbon contents ranging between 1.5% and 5%. A full spectrum of light to heavy hydrocarbons, consistent with live oils, occurs in thermal extracts of all samples. Gas chromatography fingerprints of samples with Ro > 0.7% closely resemble waxy oils derived from lacustrine organic matter (OM); fingerprints of lower maturity samples are not yet as wax rich. The inferred petroleum type organofacies of all samples is paraffinic high wax with low organic sulfur levels. Hydrocarbon generation from the least mature sample is characterized by one dominant activation energy at 55 kcal/mol, accounting for 87% of the total bulk reaction. Assuming a simplified geological scenario, i.e., a 3 K/My linear heating rate, primary petroleum is generated (transformation ratio, i.e., TR: 10%–90%) over a narrow temperature interval of only 23 °C. Onset (10% TR), maximum (Tpeak), and completion (90% TR) temperatures and Ro values are 141 °C at Ro 0.85%, 155 °C at Ro 1.08%, and 164 °C at Ro 1.2%, respectively. Primary gas generation (148–172 °C) occurs 10 °C later (300 m deeper) than the generation of C6+ compounds (138–161 °C). Secondary gas formation from oil cracking begins at 182 °C, maximizes at 197 °C, and is completed well before 225 °C (beginning of late gas generation from the secondary cracking of thermally matured, macromolecular organic matter) at 206 °C. Thus, primary and secondary oil cracking processes do not overlap under geological conditions. In line with a paraffinic high-wax oil petroleum type organofacies, cumulative fluids generated from the least mature sample fall within the black oil class over most of the primary kerogen conversion range up to 90% TR as indicated by low saturation pressures (Psat) and gas-oil-ratios generally below 160 Sm3/Sm3. Maturation results in relatively heavy fluids with Psat values in the range 40–70 bar when the free hydrocarbons, i.e., already present prior to pyrolysis, are included, and in lighter fluids with Psat values in the range 70–90 bar, when the free, mostly waxy hydrocarbons, are excluded. Systematics of physical properties and fluid compositions evolution reproduce the general behavior of naturally occurring petroleum sourced from lacustrine OM very well and fit physical properties and compositions of produced shale oils in the Songliao Basin at comparable maturity levels.

Some new insights into the kinetic compensation effect in different diffusion-controlled domain for char-CO2 gasification

The CO2 gasification reaction of lignite and coffee char are conducted at 1098–1173 K and 0.025–0.1 MPa CO2 via thermogravimetry analysis (TGA). The calculation methods of the activation energy and pre-exponential factor are further compared and analyzed. The activation energy and pre-exponential factor in the chemical-controlled domain, the external diffusion-controlled domain and the bed diffusion-controlled domain are measured to investigate the relationship between the kinetic compensation effect and mass transfer limitations. Results reveal that the normalized power-law rate equation can provide reliable kinetic parameters due to PCO2n ≠ constant (PCO2n represents the partial pressure term) at different temperatures and f(X) ≠ constant (f(X) represents the mechanism function term) at different char conversion. In the chemical-controlled or the external diffusion-controlled domains, coffee grounds char (CGC) and lignite char (LC) exhibit similar activation energies and pre-exponential factors in the char conversion range of 0.2–0.8. In the bed diffusion-controlled domain, the activation energy and pre-exponential factor increase and then decrease during the reaction process. An evident kinetic compensation effect was observed between E and ln(A0) throughout the conversion process with bed diffusion and among data from experiments with and without diffusional limitations, showing its dependence on mass transfer limitations.

Liquid Shear Exfoliation of MoS2: Preparation, Characterization, and NO2-Sensing Properties.

2D materials possess great potential to serve as gas-sensing materials due to their large, specific surface areas and strong surface activities. Among this family, transition metal chalcogenide materials exhibit different properties and are promising candidates for a wide range of applications, including sensors, photodetectors, energy conversion, and energy storage. Herein, a high-shear mixing method has been used to produce multilayered MoS2 nanosheet dispersions. MoS2 thin films were manufactured by vacuum-assisted filtration. The structural morphology of MoS2 was studied using ς-potential, UV-visible, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy (RS). The spectroscopic and microscopic analyses confirm the formation of a high-crystalline MoS2 thin film with good inter-sheet connectivity and relative thickness uniformity. The thickness of the MoS2 layer is measured to be approximately 250 nm, with a nanosheet size of 120 nm ± 40 nm and a number of layers between 6 and 9 layers. Moreover, the electrical characteristics clearly showed that the MoS2 thin film exhibits good conductivity and a linear I-V curve response, indicating good ohmic contact between the MoS2 film and the electrodes. As an example of applicability, we fabricated chemiresistive sensor devices with a MoS2 film as a sensing layer. The performance of the MoS2-chemiresistive sensor for NO2 was assessed by being exposed to different concentrations of NO2 (1 ppm to 10 ppm). This sensor shows a sensibility to low concentrations of 1 ppm, with a response time of 114 s and a recovery time of 420 s. The effect of thin-film thickness and operating temperatures on sensor response was studied. The results show that thinner film exhibits a higher response to NO2; the response decreases as the working temperature increases.

Selective synthesis of cumene from benzene and acetone: Design of tandem catalyst with hydrogenating and alkylating functions

Benzene hydroalkylation with acetone has been studied over tandem catalytic systems containing copper and zeolite components. The kinetic study in the wide range of acetone conversions allowed to determine the main reaction pathways leading to the target hydroalkylation products, cumene and diisopropylbenzenes, and to the by-products of acetone condensation. To prevent the side reaction pathways and to achieve high selectively towards target products, three strategies for assembling metal and zeolite components in the catalytic system were used: i) metal encapsulation in zeolite pores; ii) mortar mixing of copper supported on silica with zeolite component; iii) dual-bed layered arrangement of Cu/SiO2 and zeolite components. The best catalytic performance was achieved over dual-bed layered catalytic system, containing Cu/SiO2 in the upper layer and zeolite BEA in the bottom layer, which showed the highest yield of hydroalkylation products (93wt%) and stable catalyst operation.

Influence of particle size in Pd-catalysed selective hydrogenation of 1,3-butadiene

Supported Pd nanoparticles are widely used as catalysts for the selective hydrogenation of alkynes and diolefins. They have a high activity, but it remains challenging to limit over–hydrogenation to alkanes. We varied the nanoparticle size of a Pd on carbon catalyst from 2 to 17 nm and studied its effect on the catalytic activity and selectivity in the selective hydrogenation of 1,3-butadiene in the presence of an excess of propylene. The butadiene hydrogenation activity per metal surface atom increased slightly with Pd particle size, from 17 s−1 to 34 s−1 at 25 °C for 2 nm to 17 nm particles. Contrarily, the propylene hydrogenation activity decreased with particle size: from 2.6 s−1 to 0.4 s−1 from 2 to 17 nm particles. Overall, a higher product selectivity was obtained with increasing particle size over the full butadiene conversion range. Altogether, this paper provides useful insight for the rational design of monometallic Pd-catalyst for selective hydrogenation.

An offset and gain error calibration method in high-precision SAR ADCs

Successive approximation (SAR) ADC suffers from kinds of nonidealities such as offset and gain error which affect its absolute quantization range and reduce its performance in the high-precision applications. This paper presents a static offset and an embedded gain error calibration in analog domain, attempting to improve the conversion range error in SAR ADC architecture. The presented calibration technique reuses the CADC array, facilitating an analog-domain calibration within small dissipation.

Kinetics and mechanism for efficient Co(II) removal from zinc sulfate solution by ultrasonic-enhanced zinc powder replacement

The purification of zinc sulfate electrolytes in zinc hydrometallurgy has always been a vexing problem. The aggregation of zinc powder and the removal of recalcitrant Co(II) are the most challenging. Here, we propose a new method for removing Co(II) from a zinc sulfate solution using ultrasonic-enhanced zinc powder replacement. The parameters affecting Co(II) removal are investigated to obtain the optimum conditions. The Co(II) removal efficiency increases remarkably by 26.6% and the required amount of zinc powder was correspondingly reduced by 50% after introducing ultrasound and activators. The optimal dosage of activators Sb2O3 and Cu(II) is CCu(II): CSb(III): CCo(II) = 2: 1: 1. Moreover, the addition of Cu(II) does not deteriorate the quality of zinc sulfate solution because of its low residual concentration (0.84 mg/L). The removal kinetics show that the activation energy of Co-precipitation decreases by 32.27 kJ/mol, and the conversion range of the kinetic mechanism is increased to CCo(II),0 = 60–80 mg/L. The particle diameter of the purified slags decreases from 136.22 to 19.81 µm compared with that of conventional experiments. The cobalt removal mechanism mainly involves that ultrasound promotes the dispersion of zinc powder, opens the package and reduces the activation energy; the Co-Sb-Cu alloys reduce the Co-precipitation overpotential and inhibit the redissolution of Co. The proposed method presents a promising solution to the challenging problem of Co(II) removal. This study opens new possibilities for the application of ultrasound in the metallurgical fields for more efficient and energy-saving production.

Design of high-temperature shift using waste-derived synthesis gas: Thermodynamic approach and practical reaction optimization

Herein, we verify pre-reduction conditions and H2O/CO ratio to increase activity in the HTS using Fe-Cr catalyst. It was determined that the optimal H2O/CO ratio was 2.5 through the result of calculated thermodynamic equilibrium analysis and performed HTS reaction. In the Fe-Cr catalyst, HTS reaction was performed at 350 ∼ 550 °C to find the condition that Fe2O3 convert Fe3O4 without over-reduction after reduced using 2% H2/N2, 5% H2/N2, and reactant gas at various temperature (400, 500, and 600 °C). The lower the pre-reduction temperature, the higher CO conversion, but the effect of the pre-reduction gas was not significant. In addition, as a result of performing a stability test that reduced using reactant gas at 400, 500, and 600 °C, all of which maintained stability without deactivation even though had a large range of CO conversion for 50 h. Thus, we identify that the appropriate H2O/CO ratio for HTS reaction using gas produced from waste gasification is judged to be 2.5. And during the reaction using Fe-Cr, the CO conversion showed high activity when pre-reduction temperature is 400 °C. In the case of the pre-reduction gas, the activity was insignificantly affecting the pre-reduction at 400 °C, thus it is considered appropriate to use reactant gas for practical use without the need to connect the pre-reduction gas separately.

Kinetic model of CO2 methanation in a microreactor under Power-to-Gas conditions

The kinetics of CO2 methanation using a 12%Ni/γ-Al2O3 catalyst was modeled in a catalytic microreactor, considering the three-dimensional momentum, heat and species continuity balances in stationary state. The microreactor consisted of 80 microchannels with dimensions 0.45 × 0.15 × 50 mm3 in each one with an average 0.04 mm catalytic thickness. Several experimental tests were carried out at various conditions of flow rate (110, 130 and 140 mL/min), temperature (275, 300, 325 and 350 °C) and reactants partial pressure. Kinetic parameters were modeled and fitted using COMSOL Multiphysics 6.0 and Matlab 2021 R. Using the corrected Akaike information criterion (AICc), it was determined that a power kinetic model with a low kinetic exponent, 0.12 ≤ n ≤ 0.18, is adequate to represent a wide range of experimental CO2 conversion and CH4 yield (up to 86%) data. An activation energy around 83–85 kJ/mol was estimated, as well as a correlation between the different parameters of the power rate law. The temperature raise significantly increases the CO2 conversion and methane yield under the operational conditions used, due to the distance from thermodynamic equilibrium. It was numerically verified that under the experimental conditions the microchannels operate isothermally. Using this model, it is possible to evaluate the effect of operational variables (temperature, volumetric flow and H2/CO2 ratio) and reactor design (microchannel surface/volume ratio) on methane production, proving potential application in catalytic efficiency studies for Power-to-Gas applications. It is clear that processes intensification is useful to achieve higher CO2 conversions fostering sustainable development of closed-carbon production cycles.

Developing an efficient and visible prime editing system to restore tobacco 8-hydroxy-copalyl diphosphate gene for labdane diterpene Z-abienol biosynthesis.

Prime editing (PE) is a versatile CRISPR-Cas based precise genome-editing platform widely used to introduce a range of possible base conversions in various organisms. However, no PE systems have been shown to induce heritable mutations in tobacco, nor in any other dicot. In this study, we generated an efficient PE system in tobacco that not only introduced heritable mutations, but also enabled anthocyanin-based reporter selection of transgene-free T1 plants. This system was used to confer Z-abienol biosynthesis in the allotetraploid tobacco cultivar HHDJY by restoring a G>T conversion in the NtCPS2 gene. High levels of Z-abienol were detected in the leaves of homozygous T1 plants at two weeks after topping. This study describes an advance in PE systems and expands genome-editing toolbox in tobacco, even in dicots, for use in basic research and molecular breeding. And restoring biosynthesis of Z-abienol in tobacco might provide an efficient way to obtain Z-abienol in plants.

Kinetics and thermodynamics of non‐isothermal pyrolysis of Terminalia chebula branches at different heating rates

AbstractNon‐isothermal thermogravimetric tests of Terminalia chebula (Helikha) were conducted under inert N2 gas environment for temperatures (25–900°C) at heating rates of 10, 20, 35, and 55°C min−1. Kinetic triplet approximated employing five iso‐conversional methods namely, differential Friedman method (DFM), distributed activation method (DAEM), Ozawa–Flynn–Wall (OFW), Kissinger–Akahira–Sunose (KAS), and Starink (STK). Average values of activation energy (kJ mol−1) and frequency factor (min−1) calculated by the five models were 227.11, 2.98 × 1021 for DFM; 229.21, 4.63 × 1021 for KAS; 227.11, 3.81 × 1020 for OFW; 225.54, 1.15 × 1018 for STK; and 227.33, 3.02 × 1020 for DAEM respectively over the conversion range up to 0.8. In the kinetics study, correlation coefficient (R2) of greater than 0.97 is noticed in the conversion range of α = 0.1–0.8 for all models. From thermodynamic analysis, average values of ΔH (kJ mol−1), ΔG (kJ mol−1), and ΔS (kJ mol−1 K−1) for DAEM: 221.8, 179.69, and 0.065; for DFM: 236.40, 179.37, and 0.089; for KAS: 221.8, 179.69, and 0.065; for OFW: 220.22, 179.72, and 0.063; and for STK: 222.02, 179.68, and 0.066 were estimated to assess viability and reactivity of the process. Criado's master plots revealed that the data obtained from pyrolysis of selected biomass was followed a multistep reaction pathway.

Thermal degradation kinetics of recycled biodegradable and non-biodegradable polymer blends either neat or in the presence of nanoparticles using the random chain-scission model

One of the major issues in polymer recycling nowadays is related to the impact of biodegradable polymers and/or nanoparticles’ presence on the thermal degradation kinetics of non-biodegradable polymers used mainly in packaging. In this direction, the thermal degradation kinetics of PET/PLA blends was investigated using non-isothermal thermogravimetric data and a simulation model based on the random-scission mechanism. Specifically, we extended the model originally developed by Sánchez-Jiménez, Pérez-Maqueda and Criado based on the original idea of Simha and Wall to simulate the thermal degradation of polymer blends in pyrolytic conditions. A system of differential equations was set and solved based only on the kinetic parameters obtained from the neat polymers and without any additional adjustable parameter. It was found that this model describes fairly well the thermal degradation of several PET/PLA blends in a large conversion range. Deviations were observed at low conversions where degradation of PLA is promoted by ester interchange reactions with PET and at intermediate conversions where possible synergistic effects may take place. Furthermore, the addition of nanoparticles seem to retard the diffusion of the volatile degradation products out of the polymer, so that the onset of mass loss is at higher temperatures for the blend nanocomposites compared to neat blend. This was taken into account in the model by including an additional diffusion-related term to the kinetic constant of the degradation.

Current and Emerging Electrochemical Approaches for Chemical Manufacturing

R&D on electrochemical approaches for chemical manufacturing is experiencing a renaissance, the direct result of society’s desire to reduce greenhouse gas emissions of the chemical industry, aiming to be carbon neutral by 2050. Two such processes have been performed for decades at scale: the chlor-alkali process that produces chlorine from aqueous sodium chloride, and the production of adiponitrile, an intermediate in the production nylon-6,6. Water electrolysis for hydrogen production is also being deployed now at scale. This report summarizes some of the many efforts to electrify chemical conversions, often using renewable feeds like water, CO2, and biomass-derived adducts, or waste-streams from other processes. Beyond efforts to reduce emissions, a very active research community also pursues a broad range of electro-organic conversions, some of which have major advantages over conventional reaction chemistries. Overarching challenges of implementing electrochemical manufacturing approaches are also discussed (e.g., limited familiarity with electrochemical processes in chemical engineering practice, insufficient availability of electrical power, and the variability of various renewable feeds).

Fabrication of ZnWO4-SnO2 Core–Shell Nanorods for Enhanced Solar Light-Driven Photoelectrochemical Performance

This article describes the effective synthesis of colloidal SnO2 quantum dots and ZnWO4 nanorods using wet chemical synthesis and hydrothermal synthesis, respectively. The resulting ZnWO4-SnO2 core–shell nanorod heterostructure is then made, and its structural, optical, and morphological properties are assessed using XRD, SEM, TEM, and DRS. The heterojunction’s structural confinement increases the exposure of its reactive sites, and its electronic confinement promotes its redox activity. The heterostructure subsequently exhibits a smaller bandgap and better light-harvesting capabilities, resulting in increased photoelectrochemical performance. The heterostructure of core–shell nanorods shows promise for usage in a range of optoelectronic devices and effective solar energy conversion.

Evolution of functional group of lignocellulosic biomass and its delignified form during thermal conversion using synchrotron-based THz and laboratory-based in-situ DRIFT spectroscopy

In the industry, platform chemicals are traditionally synthesized from non-renewable resources. In order to determine the ideal temperature range and associated emissions for the production of platform chemicals from biomass, which is a renewable resource, mechanistic insights into the thermochemical conversion of biomass are needed. Here, the high-resolution synchrotron-based gas-phase THz (Far-IR) spectra and lab-based in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) spectra of both raw and delignified biomass have been studied to identify real-time evolution of the functional groups and any gas-phase secondary reactions during the thermochemical conversion as a function of temperature; these are linked to weight loss measurements through differential thermogravimetry. The high-resolution synchrotron-based technique and DRIFTS were used to acquire the spectra in two different wavenumber ranges of 50–600 cm−1 and 500–4500 cm−1, respectively. The synchrotron-based spectra were used to identify the major gaseous components between 300 and 500 °C of methane, ethane, acetylene and formaldehyde, and their generation followed the order 300 > 400 > 500 °C. The DRIFTS spectra showed that the covalent hydrogen bonds of both raw and delignified biomass was cleaved below 250 °C, between 250 and 300 °C the decarboxylation reaction took place, whereas between 300 and 400 °C platform chemicals (furan, levoglucosan, levoglucosenone) and aromatic compounds were formed from the dehydration of the cellulosic part of the biomass. No changes in the DRIFTS spectra were observed above 400 °C. These results suggest that 300–400 °C is the ideal temperature range for the thermochemical conversion of biomass to platform chemicals. Pyrolysis-gas chromatography/mass spectrometry (Py-GCMS) results demonstrated that the identification of platform chemicals laid the groundwork for large-scale operation.

Thermal stability of extracted lignin from novel millet husk crop residue

Recent alarming tones regarding the environment and energy crises have resulted in an emergent need for the utilization of bio-based materials. The current study aims to experimentally investigate the thermal kinetics and pyrolysis behavior of lignin extracted from novel barnyard millet husk (L-BMH) and finger millet husk (L-FMH) crop residue. The characterization techniques FTIR, SEM, XRD, and EDX were employed. TGA was performed to assess the thermal, pyrolysis, and kinetic behavior using Friedman kinetic model. The average lignin yield was obtained as 16.25 % (L-FMH) and 21.31 % (L-BMH). The average activation energy (Ea) was recorded as 179.91–227.67 kJ mol−1 for L-FMH while 158.50–274.46 kJ mol−1 for L-BMH in the conversion range of 0.2–0.8. The higher heating value (HHV) was found to be 19.80 ± 0.09 MJ kg−1 (L-FMH) and 19.65 ± 0.03 MJ kg−1 (L-BMH). The results create a possibility for the valorization of extracted lignin as a potential bio-based flame retardant in polymer composites.

The Design of 2S2L-Based Buck-Boost Converter with a Wide Conversion Range

This manuscript proposes a novel nonisolated negative output buck-boost converter topology for wide voltage conversion applications. To design this converter, a typical buck-boost converter configuration is used. In conventional buck-boost converter, the active switches designed are replaced by two switches-two inductors (2S2L) cells. The proposed converter operates in the continuous conduction mode (CCM) operation under steady-state conditions. This converter has a lower component count and low voltage stress on the switches and diodes. Moreover, the major advantage of this buck-boost converter topology is that a wide range of step-down and step-up voltage conversions can be achieved. The performance of the proposed system is designed in MATLAB/SIMULINK. A few other comparisons are also presented to demonstrate the competitiveness of the proposed buck-boost converter.

Comparative Study of Heat-Discharging Kinetics of Fe-Substituted Mn2O3/Mn3O4 Being Subjected to Long-Term Cycling for Thermochemical Energy Storage

The heat-discharging kinetics of an iron-substituted Mn2O3/Mn3O4 redox pair subjected to long-term thermal cycling tests using a temperature swing process at high temperatures was investigated for next-generation concentrated solar power plants equipped with thermochemical energy storage. The heat-discharge mode kinetics for long-term thermal-cycled samples have never been reported. Additionally, comparisons of the heat-discharge mode kinetics for both long-term thermal-cycled and as-prepared samples have never been discussed. In terms of the reproducibility and sustainability of thermochemical energy storage, kinetic evaluations of samples with thermally stable morphologies subjected to long-term thermal cycling at high temperatures are important for next-generation solar thermal power plants. For the long-term thermal-cycled sample, the A2 model based on the Avrami–Erofeev reaction describes the discharging mode behavior in a fractional conversion range of 0–0.24, the contracting area (R2) model best fits in a fractional conversion range of 0.24–0.50, and the third-order (F3) model matches in a fractional conversion range of 0.50–0.70. For the as-prepared sample, the power-law (P2) model describes the behavior of the first part of the discharging mode, whereas the Avrami–Erofeev (A4) model best fits the last half of the discharging mode. The predicted theoretical models for both samples were compared with previous kinetic data.