Thermochemical Properties Research Articles

Ruddlesden‐Popper‐type perovskite Sr3Fe2O7−δ for enhanced thermochemical energy storage

AbstractPerovskite has been considered a promising thermochemical energy storage material. Such materials can perform redox reactions reversibly under the control of oxygen partial pressure over a wide range of temperatures. Layered perovskites have been poorly studied as energy storage material, although their oxygen species exhibit good oxidation activity. In this work, Ruddlesden‐Popper‐type quasi‐2D perovskite Sr3Fe2O7‐δ and 3D perovskite SrFeO3‐δ were prepared for the testing of thermochemical energy storage properties. It was shown that the degree of reduction reaction for Sr3Fe2O7‐δ was much greater than that of SrFeO3‐δ, with change of non‐stoichiometry up to 0.79. The combined effect of thermodynamic parameters for samples on heat storage behavior was studied by Van't Hoff method. The reduction entropy of Sr3Fe2O7‐δ is much higher than that of SrFeO3‐δ, which explains the large promotion in the reaction degree of SrFeO3‐δ. The total reduction enthalpy of Sr3Fe2O7‐δ is about 2.8 times that of SrFeO3‐δ, with both reduction enthalpy and reaction entropy affecting the heat storage capacity. Sr3Fe2O7‐δ also has an attractive spectral absorption of 96.92% in the range of 300–2500 nm, which makes it advantageous in volumetric solar collector. Overall, Sr3Fe2O7‐δ offers improved performance in terms of thermochemical energy storage compared to SrFeO3‐δ.image

Thermodynamic and thermochemical properties of Cu3(PO4)2·3H2O


 
 
 
 Copper (II) orthophosphate trihydrate Cu3(PO4)2·3H2O has been synthesized by the exchange chemical reactions in aqueous solutions from the compounds Cu(NO3)2·3H2O, NH4OH and H3PO4. The final product has been investigated by using atomic absorption spectroscopy (AAS), infrared spectrometry (IRS), differential thermal analysis (DTA) and X-ray powder diffraction (XRD) techniques. For the first time, the experimental heat capacity Ср° of Cu3(PO4)2·3H2O has been investigated in the temperature range 198‒402 K. Combining the experimental results with the literature data made it possible to determine the thermodynamic and thermochemical properties, such as enthalpy НТ° , entropy SТ° , Gibbs energy GТ° , enthalpy of formation ΔHf°(T), Gibbs energy of formation ΔGf°(T) and logarithm of the equilibrium constant of formation reaction log[Kf°(T)], for the title compound. It was found that at the extreme temperatures of the experiment, Cu3(PO4)2·3H2O has Ср° = 245.96 J·mol–1·K–1, Н° = –3169.59 kJ·mol–1, S° = 311.34 J·mol–1·K–1, G° = –3231.24 kJ·mol–1 (at 198 K); Ср° = 455.31 J·mol–1·K–1, Н° = –3097.93 kJ·mol–1, S° = 551.48 J·mol–1·K–1, G° = –3319.62 kJ·mol–1, ΔHf° = –3138.48 kJ·mol–1, ΔGf° = –2625.39 kJ·mol–1, log[K ] = 341.13 (at 402 K).
 
 
 

Abstraction and addition reactions of four γ‐lactones with H‐atoms and methyl radicals

AbstractThe five‐membered cyclic esters, or γ‐lactones, are promising candidates as biofuel additives and green solvent components. A comprehensive study of thermochemical and kinetic properties of γ‐butyrolactone (GBL), γ‐valerolactone (GVL), γ‐caprolactone (GCL), and γ‐heptalactone (GHL) has been conducted. The entropy, , specific heat, , enthalpy function, , and the enthalphy of formation at 298.15 K, , as well as the adiabatic ionization potential and single bond dissociation energies are reported. Bimolecular rate constants for the abstraction of H‐atom by H• and CH are presented on a per abstractable hydrogen basis; abstraction at the tertiary carbon site is consistently favored, while abstraction by CH lags behind H•. Addition reactions of H• and CH have high barriers and favor addition to the C‐center.

Recent Trends in Treatment and Fabrication of Plant-Based Fiber-Reinforced Epoxy Composite: A Review

Natural fiber (NF) is one of the many resources that nature has provided. NFs decompose quickly and are biodegradable, renewable, and cost-effective. It may be scavenged from a variety of plant and animal sources. They are employed as reinforcing materials in polymers for NF composite development. Because of its environmental friendliness and long-term survivability, NF is growing in appeal among academics and researchers for usage in polymer composites. This study aims to offer a thorough evaluation of the most suitable and widely utilized natural fiber-reinforced polymer composites (NFPCs), along with their manufacture, processing, and applications. It also defines several external treatments of NF and their influence on the characteristics of NFPCs. The characteristics of NFPCs are affected by fiber supply, fiber type, and fiber structure. Numerous physical and chemical treatments were tested to see how they affected the thermal and strength properties of natural fiber-reinforced thermoplastic and thermosetting composites. Several polymer composite fabrication techniques were also studied. NFPCs have several disadvantages, notably low fire protection, poor strength properties, and greater moisture absorption, which have prevented their application. It is shown how NFPCs are employed in a variety of industries, particularly automotive and research industries. The review discovered that intentionally changing the regular fiber enhanced the thermochemical and physico-mechanical properties of the NFPCs by means of improving the grip between the fiber surface and the polymer framework. This study aims to provide important and fundamental facts on NF and their composites, which will aid in new investigations, the creation of a creative framework for polymer composite types, and the achievement of Sustainable Development Goals.

Oxidation of norbornadiene: Theoretical investigation on H-atom abstraction and related radical decomposition reactions

The chemical kinetics of hydrogen atom (H-atom) abstraction reactions from norbornadiene (NBD) by five radicals (H, O(3P), OH, CH3, and HO2), and the unimolecular reactions of three NBD derived radicals, were studied through high-level ab-initio calculations. The geometries optimization and vibrational frequencies calculation for all the reactants, transition states, and products were obtained at the M06-2X/6-311++G(d,p) level of theory. The zero-point energy (ZPE) corrected potential energy surfaces (PESs) were determined at the QCISD(T)/cc-pVDZ, TZ level of theory with basis set corrections from MP2/cc-pVDZ, TZ, QZ methods for single point energy calculations. Conventional transition state theory (TST) was used for the rate constants calculations of H-atom abstraction reactions by five radicals (H, O(3P), OH, CH3, and HO2) at temperatures from 298.15 to 2000 K, while the α-site H-atom abstraction reaction rate constant of NBD by OH radical has been obtained through variational transition state theory (VTST). The results show that the H-atom abstraction reactions from the α-carbon atom of NBD are the most critical channels at low temperatures. Total rate constants for H-atom abstraction reactions by OH radical are also the fastest among all of the reaction channels investigated at the temperature range from 298.15 to 2000 K. Rice-Ramsperger-Kassel-Marcus/Master Equation (RRKM/ME) has been used to calculate the pressure- and temperature-dependent rate constants for the unimolecular reactions of three related C7H7 product radicals which generated from H-atom abstraction reaction within temperature ranges of 300–2000 K and pressures of 0.01–100 atm. A combination of composite methods has been used to calculate the temperature-dependent thermochemical properties of NBD and related radicals. All the calculated kinetics and thermochemistry data can be utilized in the model development for NBD oxidation.

Results of the Study of Epigenetic Changes of Famennian–Tournaisian Carbonate Rocks of the Northern Marginal Shear Zone of the Caspian Syneclise (Kazakhstan)

Various genetic and morphological types of voids in carbonate reservoirs make it difficult to diagnose them, which can be seen in the determination of reservoir properties in the northern marginal shear zone of the Caspian Syneclise. A macro- and microscopic study of rocks was carried out by staining carbonates in thin sections with alizarin (determination of the mineral composition, structure, texture, void and fracture spaces, rock genesis). Instrumental methods (X-ray, DTA—differential thermal analysis, TGA—thermo-gravimetric analysis, and probe microanalysis) established the composition of rocks, the nature of their diagenetic transformations, and the formation of void space. The elemental and oxide composition of a number of samples was carried out using the X-ray probe microanalysis method, and mineral formations with intermediate thermochemical properties were found. The results of X-ray, DTA, and TGA measurements and the data of probe microanalysis made it possible to reveal thermally inert formations of oxides of calcium, magnesium, silicon, iron, and other compounds in the composition of carbonates. A relatively low-cost express method was used to determine the material composition and the nature of epigenetic changes and to obtain data on the void space as a result of the development of tectonic fracturing and diagenetic processes of leaching and secondary mineral formation in bedded carbonate reservoirs.

Phase Equilibria and Thermodynamic Properties of Phases in the H2O–Gd(NO3)3 System

Solid–liquid equilibria in the system H2O–Gd(NO3)3 were measured from –20 to 70°C using the isothermal saturation method. The Pitzer–Simonson–Clegg thermodynamic model was implemented to obtain the temperature dependence of Gd(NO3)3⋅6H2O solubility constant, to calculate salt solubility and to construct a phase diagram of the system from eutectic point to hydrate melting. Thermochemical properties of gadolinium nitrate aqueous solutions, such as dilution enthalpies and heat capacities, were assessed also. The model has shown to be reliable for phase equilibria calculation from –35 to 90°C and from 0 up to ~15 mol % of salt as well as the thermodynamic properties of Gd(NO3)3 aqueous solutions at room temperature and around it.

Effect of Various Compatibilizers on the Storage Stability, Thermochemical and Rheological Properties of Recycled Plastic-Modified Bitumen

Effect of Various Compatibilizers on the Storage Stability, Thermochemical and Rheological Properties of Recycled Plastic-Modified Bitumen

Ionic liquid Keggin polyoxometallates with the tris(dihexylamino)cyclopropenium cation

Five new Keggin polyoxometalate (POM) salts were prepared with the tris(dihexylamino)cyclopropenium cation [C3(NHex2)3]+ in an effort to investigate and understand the impact of combining triaminocyclopropenium (TAC) cations with POMs on their thermochemical and thermophysical properties. The tri-anions [PM12O40]3– (M = Mo, W) have high melting salts (Tm = 140 and 129 °C, respectively), whereas the tetra-anions [PVMo11O40]4– and [HPV2M10O40]4– (M = Mo, W), despite the increased electrostatic charge, have lower and very similar melting points (Tm ∼ 82 °C). The solid-state structures are all very similar, however, the tetra-anionic salts have a double layer of cations (compared to a single layer for the tri-anionic salts) and the electrostatic repulsion between these layers is likely responsible for the lower and similar melting points, as well as their increased solubility in non-polar solvents. The salts were also characterised by TGA, DSC, solubility studies, X-ray crystallography, NMR and infrared spectroscopy.

Hydrogen physisorption on the (BeO)n, B2H4(Be,Ti), and B6Ti3 metal clusters: a computational study of energies and atomic charges.

The equilibrium structures of BeO clusters and Be,Ti-decorated boranes were computed with the ωB97X-D method and the 6-31G + (2d,2p) and aug-cc-pVTZ basis sets to study their intermolecular interactions with hydrogen molecules. Thermochemical and molecular properties such as the harmonic vibrational frequency, dipole and quadrupole moments, and atomic charges are employed to understand the attractive interactions that control the adsorption process. Comparison of molecular properties and atomic charges of the studied compounds before and after H2 molecule adsorption shows that most of the interactions among the BeO clusters and boranes with H2 molecules constitute a combination of dispersion, electrostatic, and weak charge transfer interactions. Calculated values of Hirschfeld atomic charges and ΔEe (in parenthesis) (BeO)4.8H2 (0.028 e and -2.0kcal.mol-1), (BeO)2.12H2 (0.030 e and -2.8kcal.mol-1), B6Ti3.10H2 (0.045 e and -15.4kcal.mol-1), and B6Ti3+.10H2 (0.058 e and -15.3kcal.mol-1) show qualitative correlation between hydrogen atomic charges and electronic energy of hydrogen interaction. The ωB97X-D/6-31 + G(2d,2p) values of Gibbs free energy at 298.15K for (BeO)4.8H2 B2H4Ti.4H2 and B6Ti3.10H2 clusters are equal to -5.0, -4.9, and -5.1kcal.mol-1, respectively, which are within the range of energy parameters of materials that could be employed in hydrogen storage tanks for light vehicles.

Influence of Short-Pulse Microwave Radiation on Thermochemical Properties Aluminum Micropowder.

The thermochemical properties of Al micropowder after exposure to microwave irradiation were investigated. The Al micropowder was exposed to microwave irradiation in air with a frequency of 2.85 GHz, a power density of 8 W/cm2, and a pulse duration of 25 ns and 3 µs. The thermochemical parameters of the irradiated metal powders were determined by the method of thermal analysis at the heating in air. It was found that an increase in the duration of microwave pulses and irradiation time leads to the thermal annealing of the metal particles, and the thermal processes of melting and sintering begin to dominate over non-thermal processes. The specific thermal effect of irradiated Al micropowder oxidation increases from 7744 J/g to 10,154 J/g in comparison with the unirradiated powder. The modeling of thermal heating processes of aluminum (Al) micropowder under the action of pulsed microwave radiation has been performed. It is shown that with an increase in the duration of microwave pulses and irradiation time, a significant heating of the Al micropowder occurs, leading to its melting and sintering. The results of modeling on the action of microwave radiation on the Al micropowder were compared with experimental results.

Sustainable jute fiber reinforced polylactic acid composite: Thermochemical and thermomechanical characteristics

The necessity of utilizing biodegradable and naturally sourced materials is rising all over the world. The preferred composite today are mostly sustainable but compatibility issues between the matrix and fiber still requires further investigation. The study presents development of Jute fiber (JF) reinforced Polylactic acid (PLA) composite with Fusabond (FB) as an interfacial modifier by using extrusion. The addition of interfacial modifier enhanced the thermomechanical and thermochemical properties of resultant composite. The improvement in elastic modulus and tensile strength is evident when 30%JF with 3%FB was utilized. The DMA result shows that the addition of Fusabond as interfacial modifier in jute fiber reinforced polylactic acid composite improves the storage modulus and enhances the toughness by reducing tanδ peak. Furthermore, SEM micrograph demonstrates the improvement in interfacial suitability between jute fiber and polylactic acid matrix when Fusabond is added. The X-ray tomography result shows when jute fiber content is 30% in PLA matrix higher degree of anisotropy is achieved which is 29%.

Investigation of Thermochemical Properties and Pyrolysis of Barley Waste as a Source for Renewable Energy

Energy consumption is rising dramatically at the price of depleting fossil fuel supplies and rising greenhouse gas emissions. To resolve this crisis, barley waste, which is hazardous for the environment and landfill, was studied through thermochemical characterization and pyrolysis to use it as a feedstock as a source of renewable energy. According to proximate analysis, the concentrations of ash, volatile matter, fixed carbon, and moisture were 5.43%, 73.41%, 18.15%, and 3.01%, consecutively. The ultimate analysis revealed that the composition included an acceptable H/C, O/C, and (N+O)/C atomic ratio, with the carbon, hydrogen, nitrogen, sulfur, and oxygen amounts being 46.04%, 6.84%, 3.895%, and 0.91%, respectively. The higher and lower heating values of 20.06 MJ/kg and 18.44 MJ/kg correspondingly demonstrate the appropriateness and promise for the generation of biofuel effectively. The results of the morphological study of biomass are promising for renewable energy sources. Using Fourier transform infrared spectroscopy, the main link between carbon, hydrogen, and oxygen was discovered, which is also important for bioenergy production. The maximum degradation rate was found by thermogravimetric analysis and derivative thermogravimetry to be 4.27% per minute for pyrolysis conditions at a temperature of 366 °C and 5.41% per minute for combustion conditions at a temperature of 298 °C. The maximum yields of biochar (38.57%), bio-oil (36.79%), and syngas (40.14%) in the pyrolysis procedure were obtained at 400, 500, and 600 °C, respectively. With the basic characterization and pyrolysis yields of the raw materials, it can be concluded that barley waste can be a valuable source of renewable energy. Further analysis of the pyrolyzed products is recommended to apply in the specific energy fields.

Thermochemical Evaluation of Different Waste Biomasses (Citrus Peels, Aromatic Herbs, and Poultry Feathers) towards Their Use for Energy Production

The biomass waste obtained at the end-of-pipe of the extraction industry can be used as fuel for energy production, aiming at cost reduction/waste disposal issues. However, few systematic investigations into the calorific value of these residues are reported in the literature. In this work, the thermochemical properties of solid residues from different biomasses (residues from citrus peels, leaves, flowers, stems, and poultry feathers used for extraction) as potential biomass fuels have been investigated. The heat of combustion (ΔcH) of the solid residues from citrus (orange, tangerine, lemon, grapefruit, and pomelo), aromatic herbs (rosemary, lavender, thyme, Artemisia vulgaris L. and Ruta chalepensis L.), and poultry feathers biomasses was measured by direct calorimetry. The results were compared with the higher heating values (HHV) calculated using the elemental (CHNOS) and thermogravimetric (TGA) analyses data and with the enthalpy of combustion calculated using the biomass composition predicted by FTIR spectroscopy in tandem with chemometrics. The calculated values match with the corresponding experimental values of ΔcH. The heat of combustion highlights the energetic features of solid residues for their potential uses as alternative biomass for energy production. This information is essential to evaluate the employment of solid residues as fossil fuel substitutes.

ТЕРМОХИМИЧЕСКИЙ РАСЧЕТ РАВНОВЕСНЫХ СООТНОШЕНИЙ ФАЗ ГИДРОКСИДА АЛЮМИНИЯ

A search and analysis of thermodynamic data on the phases formed during the precipitation of aluminium hydroxide from acidic salts’ solutions was carried out in order to further study the equilibrium relations of aluminium hydroxide. The study of literature on the thermodynamic properties of various aluminium hydroxides modifications obtained by low-temperature calorimetry revealed a contradiction in the calorimetric data on boehmite, which is explained by the difference in thermochemical properties between the phases of crystalline and gelatinous boehmite (boehmite and pseudoboehmite). Saturation indices of aluminium hydroxide phases were plotted, which, in turn, made it possible to compare these phases in terms of their stability and confirm certain regularities characterizing the precipitation conditions

How height-related variations in hybrid poplars affect composition and pyrolytic behaviour: The key role of lignin maturity during woody-biomass pyrolysis

This work aims to explore the height-related changes in chemical composition, calorific value, and thermochemical behavior during pyrolysis of four types of hybrid poplars (AF2, Beaupré, I214 and Monviso) and their structural components. The samples were collected from a Short Rotation Woody Coppice (SRWC) located in an abandoned opencast mine in the north of Spain. The effect of lignin and extractives (hydrophilic and hydrophobic ones) on wood pyrolysis, as well as the relationships between thermochemical properties and lignocellulosic composition, extractive content and lignin maturity, are investigated. The higher bark content of the top sections influences chemical and structural compositions. They have higher calorific values and more lignin, extractives, N and S contents, yielding more fixed carbon and ash. Additionally, the lignin of the top sections is less thermally stable. The isolation of structural components from the samples shifts the maximum volatile emission to higher temperatures for lignin and lower temperatures for holocellulose and cellulose, compared with those in the un-extracted samples. Lignin has a notable influence on wood decomposition since: (i) until its β-O-4 linkages and hemicellulose/lignin connections have been broken, cellulose devolatilization does not reach its maximum rate; and (ii) its removal reduces sample thermal stability, its effect being more significant than that of extractive removal. DRIFT spectroscopy is a valuable technique for predicting variations in chemical and thermochemical characteristics with the height of the wood sample. Several indices representing ratios of the maximum absorbance of specific signatures of lignin and cellulose could be appropriate for quick preliminary screening of woody biomass.

Aza-bicyclooctadiene/tetracyclooctane couples as promising photoswitches for molecular solar thermal energy storage applications

The position of N in the aza-BOD/TCO photoswitching systems govern the thermochemical and photophysical properties for molecular solar thermal energy storage application.

Greater transferability and accuracy of norm-conserving pseudopotentials using nonlinear core corrections.

We present an investigation into the transferability of pseudopotentials (PPs) with a nonlinear core correction (NLCC) using the Goedecker, Teter, and Hutter (GTH) protocol across a range of pure GGA, meta-GGA and hybrid functionals, and their impact on thermochemical and non-thermochemical properties. The GTH-NLCC PP for the PBE density functional demonstrates remarkable transferability to the PBE0 and ωB97X-V exchange-correlation functionals, and relative to no NLCC, improves agreement significantly for thermochemical benchmarks compared to all-electron calculations. On the other hand, the B97M-rV meta-GGA functional performs poorly with the PBE-derived GTH-NLCC PP, which is mitigated by reoptimizing the NLCC parameters for this specific functional. The findings reveal that atomization energies exhibit the greatest improvements from use of the NLCC, which thus provides an important correction needed for covalent interactions relevant to applications involving chemical reactivity. Finally we test the NLCC-GTH PPs when combined with medium-size TZV2P molecularly optimized (MOLOPT) basis sets which are typically utilized in condensed phase simulations, and show that they lead to consistently good results when compared to all-electron calculations for atomization energies, ionization potentials, barrier heights, and non-covalent interactions, but lead to somewhat larger errors for electron affinities.

Cation synergy in Sr and Al substituted LaMnO3 during solar thermochemical CO2 splitting

The influence of bond polarity on the thermochemical redox properties of a series of cation substituted perovskite oxygen carriers is reported.

Low-melting multicharge ionic liquids with [Ln(NO3)5]2- (Ln = Ho-Lu): structural, electrostatic, thermochemical, and fluorescence properties.

A series of green and safe heavy-rare-earth ionic liquids were obtained using a straightforward method. The stable structures of these ionic liquids, characterized by high-coordinating anions, were confirmed by nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, and single crystal X-ray diffraction (XRD). These ionic liquids exhibited wide liquid phase intervals and excellent thermal stability. The bidentate nitrato ligands occupied a sufficient number of coordination sites on the lanthanide ions, resulting in the formation of water-free 10-coordination structures. To explain the anomalous melting points observed in these multi-charged ionic liquids, a combination of experimental data and theoretical studies was employed to investigate the relationship between the electrostatic properties and the melting point. The electrostatic potential density per unit ion surface and volume were proposed and utilized for melting point prediction, demonstrating good linearity. Furthermore, the coordinating spheres of the lanthanide ions in these ionic liquids were devoid of luminescence quenchers such as O-H and N-H groups. Notably, the ionic liquids containing Ho3+, Er3+, and Tm3+ exhibited long lifetime near-infrared (NIR) and blue emissions, respectively. The UV-vis-NIR spectra revealed numerous electronic transitions of the lanthanide ions, which were attributed to their unique optical properties.