Average Value Of Activation Energy Research Articles

Effect of the heat treatment on the physicochemical characteristics of rubberwood: Results of thermal analysis and FTIR spectroscopy

Heat treatment is an environmentally friendly method used to improve properties of rubberwood. In this work, the changes in the chemical composition, thermal behavior and thermal degradation kinetics of heat-treated Hevea brasiliensis (rubber tree) were evaluated using thermogravimetry, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The rubberwood samples were exposed to temperatures of 180 °C and 220 °C in air under atmospheric pressure for durations of 15 25 and 35 h. Thermal analysis revealed degradation of hemicelluloses, an increase in the relative proportions of cellulose and lignin in heat-treated rubberwood. The thermal decomposition of rubberwood heat-treated at 220 °C started at a higher temperature compared to untreated wood. A shift in the position of peaks on differential thermogravimetry and differential scanning calorimetry curves of heat-treated samples was observed, indicating changes in the structure of wood polymers. The temperature of heat treatment had a stronger effect on the chemical composition of rubberwood than duration. Significant changes in the chemical composition of rubberwood occurred after the treatment duration of 15 h at both 180 °C and 220 °C. The duration of 25 h and 35 h had no further substantial effect. The isoconversional method of Flynn-Wall-Ozawa was used to determine the kinetics of thermal degradation of untreated and heat-treated rubberwood. It is found that the average values of activation energy in the conversion degree range of 0,05 - 0,65 (the thermal degradation of polysaccharides) increased with increasing treatment temperature and duration. Fourier transform infrared spectra demonstrated alterations in wood polymers.

The role of Ni minor additions on the mechanical characteristics of Sn-1.5Ag-0.5 wt.% Cu (SAC155) Pb-free solder alloy

AbstractMicrostructure analysis, thermal behavior, and tensile creep characteristics of the Sn-1.5Ag-0.5Cu-x wt.% Ni (SAC155-xNi, x = 0, 0.05, 0.1, 0.2, and 0.5 wt.%) solder alloys have been examined. The Ni additions have greatly modified the microstructure of Ni-free alloy into bulky fibrous eutectic regions and included the contemporary (Cu, Ni)6Sn5, and (Ni, Cu)3Sn4 IMCs. Ni additions slightly increased solidus temperature and melting temperature of them. The results of tensile creep resistance have shown dependence on Ni content and testing temperatures due to bulky fibrous eutectic regions and finer IMCs. Creep rates vary with Ni content across all temperatures and stresses. The SAC155-0.05Ni alloy has the lowest and the SAC-0.0Ni alloy has the highest creep rates at all tested conditions. The delicate dispersed IMCs of Ag3Sn and Cu–Ni–Sn resulted in a significant increase in stress exponent (n$$\approx $$ ≈ 5–8), enhancing its deformation resistance. The $$n$$ n values of alloys decrease as the testing temperature rises due to a change in the dominant creep mechanism. The average values of activation energy (Q) of SAC155-xNi alloy ranged from 60.20 to 68.02 kJ/mol. These Q values are coherent to the process of pipe self-diffusion through dislocation cores.

Probing pyrolysis conversion of separator from spent lithium-ion batteries: Thermal behavior, kinetics, evolved gas analysis and aspen plus modeling

The exponential growth in the consumption of lithium-ion batteries (LIBs) has resulted in a concomitant increase in the spent LIBs. Multi-component recycling is a highly desirable and beneficial process, yet the separator component remains overlooked. This study examined the thermal behavior, kinetics, thermodynamics, and evolved products of separator pyrolysis in N2 and CO2 atmospheres. Furthermore, the conversion was modeled using Aspen Plus and a sensitivity analysis was conducted to investigate the impact of varying operating conditions. The findings indicated that the whole degradation process could be divided into three stages: below 200 °C, 200–550 °C and 550–900 °C. The evolved products at peak temperatures of 485 °C in N2 and 500 °C in CO2 were composed of olefins and alkanes. The average apparent activation energy values were determined to be 222.78 kJ mol−1 and 159.36 kJ mol−1 in the N2 and CO2 atmospheres, respectively. Thermodynamic analysis indicated that the separator decomposition was an endothermic and non-spontaneous process. Aspen Plus modeling results were in agreement with the experimental data. The sensitivity analysis revealed that an increase in temperature lead to an increased content of lighter compounds (≤C9) and a decrease in the proportion of heavier compounds (>C10) in the pyrolysis products.

Combined kinetic analysis of thermal degradation characteristics and reaction mechanism of thin intumescent fire-retardant coating of steel structure

To determine the thermal kinetic triplets and elucidate the reaction mechanism of thin intumescent fire-retardant coatings (IFR) of steel structures, one efficient combined kinetic approach was implemented in this study. Thermogravimetric experiments were conducted in air atmosphere at four heating rates, and the whole IFR thermal degradation process was divided into two stages. The average activation energy values derived by model-free methods were 78.9 kJ/mol and 175.16 kJ/mol for Stage I (0<α < 0.2) and Stage II (0.2<α < 0.9), respectively. Furthermore, the linear Coats-Redfern (CR) and non-linear Masterplots models were applied to identify the possible reaction mechanism. It was found that the F3/2 mechanistic model was better suited to the main thermal degradation process. Then model reconstruction based on the F3/2 mechanism model was performed. The results showed that the reconstructed model had a strict linear relationship in the independence analysis and KCE analysis, along with a good agreement between the theoretical and experimental results. The current study provided new insights into the systematic thermal degradation mechanism of IFR, and the proposed kinetic model would be helpful for the thermal protection prediction for steel structure during fire.

Kinetic analysis and calculation correction methods for moisture evaporation rate in pine lignocellulosic biomass

This study investigates the kinetics of moisture evaporation in pine wood during the drying stage, focusing on analyzing thermogravimetric (TG) curves. The research is based on the kinetic rate model and TG curves obtained at various heating rates, specifically 5, 10, 15, and 20 K/min for the heat release rate, within a temperature range from room temperature to 473 K. Utilizing thermogravimetric experiments and the kinetic rate model, the apparent activation energy and pre-exponential factor are calculated. Further refinement of these calculations is achieved using the Nelder-Mead algorithm. The results show good agreement between the average values of the apparent activation energy (37.88 kJ/mol) and pre-exponential factor (4458.20 s−1) and experimental measurements in the initial and later drying stages, with discrepancies noted in the middle stage. Establishing a relationship between the correction coefficients of these parameters and the heating rate leads to a reduction in calculation errors. Notably, the pre-exponential factor is found to be influenced by heating rates, while the apparent activation energy remains relatively stable. Moreover, the errors are significantly reduced after correction, and the error curve of 10 K/min is the most significant. Overall, the proposed correction method holds promise for accurately calculating moisture evaporation rates in lignocellulosic biomass, offering valuable insights for biomass drying applications.

Biopolymeric degradation of jute sticks under pyrolytic thermal stresses

For the first time pyrolytic degradation of biopolymers and multi-pseudo component of jute sticks (JS) was executed through thermogravimetric analysis. Gaussian deconvolution of first order derivative have been registered in the current manuscript to find individual signals related to each pseudo component (hemicellulose, cellulose and lignin) in biomaterial. The JS characteristics, pyrolysis reaction kinetics, reaction mechanism and nature of the volatile compounds released were examined by various analytical instruments and methods, such as elemental analyzer, FTIR, AAS, TGA, GC-MS and kinetics models. The average activation energy values for JS 243.77, 234.05, 246.61, 246.74 and 260.03 kJ.mol−1 when OFW, KAS, STM, TANG and Friedman models, respectively, were used for analysis. Thermodynamic parameters (ΔH, ΔS, and ΔG) of different component of JS were also evaluated and discussed in the current context. Z(α) analysis has shown that the experimental curves have followed Avrami- Erofeyev (A2, A3, A4), power-law (P2), geometric (R2, R3), diffusional (D1, D2, D3) and reaction (F1) curves according to Criado’s master plots, indicating complex nature of pyrolysis process. Finally, it was confirmed that alcohols are major pyrolysates, followed by hydrocarbon and benzene among all other components released during pyrolysis action of JS. The finding of the study contributes to the potential of jute stick as a raw material for bioenergy and renewable chemical production. It also proves to be useful in the design and optimization of JS-based thermochemical degradation processes.

Thermogravimetric pyrolysis investigation of pistachio shell for its potential of thermal properties, kinetics and thermodynamics

In order to design and optimize thermochemical systems for the production of bioenergy understanding the energy capacity of the pistachio shell and its kinetics of degradation is crucial. The Thermogravimetric analysis at different heating rates of biomass was studied along with thermodynamic study, primary characterizations like the composition of biomass, heating value and a reaction mechanism-assisted kinetic model. Nitrogen gas flow rate is used for thermogravimetric analysis (TGA), which is performed at 10, 15, 20 and 30 ℃/min different heating rates from room temperature to 900 ℃. The output also shows that maximal degradation took place between 180 and 430 °C. The various iso-conversional models, such as Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink and Friedman, are used to calculate kinetic and thermodynamic parameters, which give the average value of activation energy as 172.29, 170.47, 169.79, and 193.25 kJ/mol. The average values of Gibbs free energy for the FWO, KAS, Starink and Friedman techniques were found to be 176.49, 1176.54, 176.29, and 175.78 kJ/mol, respectively.Graphical

Dynamic strain aging and recrystallization mechanisms in laser powder bed melt printing of highly textured Hastelloy X

Hastelloy X (HX) is used in a wide range of aerospace applications due to its excellent high-temperature properties, Dynamic strain aging (DSA) and Dynamic recrystallization (DRX) are of great interest as they affect the mechanical behavior at high temperatures. In this study, the serrated flow behavior of highly textured Hastelloy X fabricated by laser powder bed fusion (LPBF) is investigated during uniaxial straining over a wide range of temperatures (20–800 °C) and strain rates (5×10−2 s−1 to 5×10−4 s−1). The alloy exhibits different types of tensile serrated flow in the temperature range of 200–600 °C. The alloy has been shown to have a very good tensile flow behavior. The presence of the Portevin-Le Chatelier effect (PLC) due to dynamic strain failure was observed at temperatures lower than 600 °C, respectively, with an average activation energy value of 45 kJ/mol calculated using the quasi-static aging (McCormick) model, and an average activation energy value calculated using the solute resistance (Cottrell) model of 41.8 kJ/mol, which is significantly lower than the 80–130 kJ/mol of conventionally fabricated HX. The effects of temperature and strain rate on fracture morphology and microstructure were analyzed by SEM, and the dynamic recrystallization behavior and nucleation mechanism were characterized by electron backscatter diffraction (EBSD). The changes in the content of recrystallized texture Cube and deformed texture Goss at different deformation temperatures are explained, and the dynamic recrystallization mode changes, from continuous dynamic recrystallization (CDRX) to discontinuous dynamic recrystallization (DDRX) as the deformation temperature increase. Verification of the different DRX mechanisms contributes to a comprehensive understanding of the microstructural evolution of the hot deformation of HX fabricated by LPBF.

Optimization and prediction of thermodynamic parameters in co-pyrolysis of banana peel and waste plastics using AIC model and ANN modeling

The optimization and prediction of thermodynamic parameters including synergistic effects, and kinetic analysis in co-pyrolysis of banana peel (BP) and waste polystyrene (PS) plastic at different heating rates using ANN and AIC models has been performed. Thermogravimetric analysis was performed to determine the initial, maximum, and final degradation temperatures. The synergistic effect was studied using additive formula to determine the theoretical thermal behavior and compared with experimental TGA data. Kinetic parameters were determined by using the advanced isoconversional (AIC) model for estimation of activation energy (Eα), Criado master plot for reaction mechanism (f(α)), and compensation method for frequency factor (Aα). The analysis showed that the average activation energy values were 182.5, 140.6, and 161.8 kJ mol−1 for PS, BP, and PS+BP, respectively. It also clearly shows positive synergy in co-pyrolysis of PS and BP by reducing 11.3 % activation energy compared to that of PS alone. The frequency factor was found to be 1.0 × 1014, 1.0 × 1015, and 1.0 × 1023 s−1 for PS, BP, and PS+BP, respectively. The reaction mechanism was identified as R3, D4, and D4+R3 for PS, BP, and PS+BP, respectively. Further, the obtained kinetic parameters were used to determine the thermodynamic parameters such as enthalpy (ΔH), Gibbs energy (ΔG), and Entropy (ΔS). Finally, ANN was designed to address the co-pyrolysis behavior subjected to various heating rates. Subsequently, the trained ANN model (5 × 4×4 × 4) was employed to forecast thermal degradation behavior. Impressively, the model yielded highly accurate results with a correlation coefficient R2 > 0.998 in each case. The optimized model was further used to predict TGA data and activation energy for unknown mixtures of PS and BP. The suggested ANN model showed a great advantage in optimizing to avoid extensive experiments at various heating rates to achieve the goal.

Non-isothermal kinetics of the organocatalytic ring-opening polymerization of ε-caprolactone with metal-free α‑hydroxy acids: Eco-friendly and facile synthesis process

Metal-free and green α‑hydroxy acids (AHA) such as l-malic (MA), DL-mandelic acid (MDL), and citric acid (CA) were successfully and effectively utilized as an effective initiator for the solvent-free ring-opening polymerization (ROP) of ε-caprolactone (ε-CL). The performance of AHAs in the polymerization of ε-CL was completely and powerfully investigated via the non-isothermal differential scanning calorimetry (DSC). The proceed of ROP of ε-CL with AHAs could be real-time monitored by the obtained polymerization exotherms at different heating rates. The polymerization exotherms obtained from the ROP of ε-CL with CA occurred at a lower temperature range than MA, and MDA, respectively. From the kinetics study, the average activation energy (Ea) values for the ROP of ε-CL with CA (38.0 ± 1.8 kJ mol−1) were lower than MA (45.2 ± 3.6 kJ mol−1) and MDA (48.8 ± 6.2 kJ mol−1). Using the first-order model fitting, the values of pre-exponential factor (lnA0) for the ROP of ε-CL with CA, MA, and MDA were 7.0 ± 0.3, 8.5 ± 0.2, and 8.9 ± 0.3, respectively. The effectiveness of AHAs in the synthesis of PCL was clarified by conducting a larger-scale (4.0000 g) polymerization using conventional heating and microwave (MW) irradiation methods. From conventional heating, the green AHAs produced PCL with the number average molecular weight (Mn) and dispersity (Đ) values in the range of 5.18 × 103 - 1.43 × 104 g mol−1 and 1.14–2.02, respectively. The irradiation by MW could enhance the synthesis of PCL by reducing the synthesis time. By using the MW power of 450 W and irradiation time of 30 min, the PLC was obtained from the ROP of ε-CL with MA and MDA initiators, and the Mn of the obtained PCL from MW heating was 4.28 × 103 - 8.45 × 103 g mol−1. The mechanism for the ROP of ε-CL with all AHAs was proposed through the activated monomer mechanism.

Mesoporous Ag@WO3 core–shell, an investigation at different concentrated environment employing laser ablation in liquid

In this study, silver-tungsten oxide core–shell nanoparticles (Ag–WO3 NPs) were synthesized by pulsed laser ablation in liquid employing a (1.06 µm) Q-switched Nd:YAG laser, at different Ag colloidal concentration environment (different core concentration). The produced Ag–WO3 core–shell NPs were subjected to characterization using UV–visible spectrophotometry, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive spectroscopy, electrical analysis, and photoluminescence PL. The UV–visible spectra exhibited distinct absorption peaks at around 200 and 405 nm, which attributed to the occurrence of surface Plasmon resonance of Ag NPs and WO3 NPs, respectively. The absorbance values of the Ag–WO3 core–shell NPs increased as the core concentrations rose, while the band gap decreased by 2.73–2.5 eV, The (PL) results exhibited prominent peaks with a central wavelength of 456, 458, 458, 464, and 466 nm. Additionally, the PL intensity of the Ag–WO3-NP samples increased proportionally with the concentration of the core. Furthermore, the redshift seen at the peak of the PL emission band may be attributed to the quantum confinement effect. EDX analysis can verify the creation process of the Ag–WO3 core–shell nanostructure. XRD analysis confirms the presence of Ag and WO3 (NPs). The TEM images provided a good visualization of the core-spherical shell structure of the Ag–WO3 core–shell NPs. The average size of the particles ranged from 30.5 to 89 (nm). The electrical characteristics showed an increase in electrical conductivity from (5.89 × 10−4) (Ω cm)−1 to (9.91 × 10−4) (Ω cm)−1, with a drop in average activation energy values of (0.155 eV) and (0.084 eV) at a concentration of 1.6 μg/mL of silver.

Kinetics Study of PVA Polymer by Model-Free and Model-Fitting Methods Using TGA.

Thermogravimetric Analysis (TGA) serves a pivotal technique for evaluating the thermal behavior of Polyvinyl alcohol (PVA), a polymer extensively utilized in the production of fibers, films, and membranes. This paper targets the kinetics of PVA thermal degradation using high three heating rate range 20, 30, and 40 K min-1. The kinetic study was performed using six model-free methods: Freidman (FR), Flynn-Wall-Qzawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink (STK), Kissinger (K), and Vyazovkin (VY) for the determination of the activation energy (Ea). TGA showed two reaction stages: the main one at 550-750 K and the second with 700-810 K. But only the first step has been considered in calculating Ea. The average activation energy values for the conversion range (0.1-0.7) are between minimum 104 kJ mol-1 by VY to maximum 199 kJ mol-1 by FR. Model-fitting has been applied by combing Coats-Redfern (CR) with the master plot (Criado's) to identify the most convenient reaction mechanism. Ea values gained by the above six models were very similar with the average value of (126 kJ mol-1) by CR. The reaction order models-Second order (F2) was recommended as the best mechanism reaction for PVA pyrolysis. Mechanisms were confirmed by the compensation effect. Finally, (∆H, ∆G, and ∆S) parameters were presented and proved that the reaction is endothermic.

AC conductivity and dielectric relaxation behavior of lamellar benzyltrimethylammonium/V2O5 nanocomposite

Lamellar benzyltrimethylammonium/V2O5 nanocomposite has been prepared hydrothermally. Electrical and dielectric properties as a function of temperature and frequency of the nanocomposite were reported. The decrease in Z′ with increasing temperatures indicates the existence of a negative temperature resistance coefficient (NTCR) characteristic of the semiconductor material. For T > 432 K, the values of the exponents decrease with increasing temperature indicating that the CBH model is the likely mechanism. When T < 432 K, the NSPT model is an adequate mechanism to characterize electrical conduction. Variation of log(σdc) versus 103/T reveals a rupture around 432 K and the average activation energy values are of the order of 0.240 and 0.085 eV. It has been found that the dielectric constant and the dielectric loss decrease when frequency increases which is explained by the hopping of electrons between V4+/V5+. Moreover, the presence of non-Debye type of relaxation was detected by the complex modulus analysis.

Study on non-isothermal pyrolysis of Azadirachta Indica for kinetic triplets and thermodynamics evaluation

Exploring kinetics and thermodynamics of biomass pyrolysis process is imperative for optimizing the process. This study employs various model-free iso‐conversional methods and a model-fitting method to investigate the kinetics and thermodynamics of non-isothermal pyrolysis of Azadirachta indica biomass under four distinct heating rates of 10, 20, 30 and 40 °C/min. Average values of activation energy and pre-exponential factor ranged from 187.613 to 196.635 kJ/mol and 5.068×1014 − 1.178×1022 min−1, respectively, indicating an endothermic and complex nature of reaction. Integral master plots proved superior in revealing the reaction mechanism, although Criado's master plot unveiled a combination of reaction models, aligning with the intricate degradation mechanisms of biopolymers. The average enthalpy change, Gibbs free energy change and entropy change values spanned from 182.425 to 191.638 kJ/mol, from 167.288 to 173.742 kJ/mol and from 0.014 to 0.039 kJ/mol·K, respectively.

Hot processing map and high temperature deformation behaviour of TB17 Ti alloy

The thermal compression experiments of TB17 titanium alloy under different thermal deformation process parameters were carried out using a thermal simulation compressor. The high-temperature plastic flow behaviour of the alloy was studied. It was found that with the decrease of the deforming temperature and the increase of the strain rate, the flow stress increased, and the discontinuous yield phenomenon occurred in hot deformation. The larger the strain rate, the more obvious the discontinuous yield phenomenon. The thermal activation energy Q decreased with the increase of strain, and the average value of activation energy Q is 209.54 KJ / mol. The constitutive equation of high-temperature plastic flow of TB17 titanium alloy was established. The predicted values of this equation are in good agreement with the experimental values. The average error is 3.987 %, and the correlation coefficient is 0.9972, which has high accuracy. Based on the Prasad criterion, the hot processing map of TB17 titanium alloy was constructed. It was found that the flow instability zone was mainly concentrated in the high strain rate region. The flow instability zone was determined to be 795 °C ~ 895 °C, 0.046s-1 ~ 1s-1, and the stable deformation zone was mainly located in the region with high temperature and low strain rate. The optimum processing parameter range is 860 °C ~ 895 °C, 0.001 s-1 ~ 0.025 s-1.

Effects of green and innovative pretreatment techniques on kinetic parameters of sunflower seed husk

The effects of green pretreatment processes, such as ultrasonic process (US) and deep eutectic solvent (DES), applied to the biomass on kinetic parameters are as important as their effects on characteristic properties. Process conditions and course of reaction progression depend on the knowledge about kinetic parameters, activation energy and reaction model of thermal degradation in scale-up studies. Therefore, in this study, the change in the kinetic parameters with US applied with both distilled water and DES (glycerol:sodium acetate) at 100 W power and 20 kHz frequency for 10 minutes to sunflower seed husk (SSH) was revelaed. Isoconversional methods Kissinger-Akahira-Sunose (KAS) and Flynn- Wall-Ozawa (FWO) were preferred for the evaluation of activation energy of SSH and pretreated SSH at 15°C/min, 20°C/min and 25°C/min heating rates. US pretreatment with DES instead of water resulted in increment of average activation energy values (Ea) from 113.13 to 143.65 kJ/mol in the KAS method. Ea values for all SSH samples changed in the range of 87.72-143.65 kJ/mol and higher Ea values was obtained with KAS method for pretreated SSH samples. Consequently, the use of DES in US pretreatment was more effective to change kinetic parameters of SSH compared to water.

Reutilization of Reclaimed Asphalt Binder via Co-Pyrolysis with Rice Husk: Thermal Degradation Behaviors and Kinetic Analysis.

Realizing the utilization of reclaimed asphalt binder (RAB) and rice husk (RH) to reduce environmental pollution and expand the reutilization technique of reclaimed asphalt pavement (RAP), co-pyrolysis of RAB with RH has great potential. In this study, the co-pyrolysis behaviors, gaseous products, and kinetics were evaluated using thermogravimetric analysis and Fourier transform infrared spectroscopy (TG-FTIR). The results showed that incorporating RH into RAB improved its pyrolysis characteristics. The interactions between RAB and RH showed initial inhibition followed by subsequent promotion. The primary gaseous products formed during co-pyrolysis were aliphatic hydrocarbons, water, and carbon dioxide, along with smaller amounts of aldehydes and alcohols originating from RH pyrolysis. All average activation energy values for the blends, determined through iso-conversional methods, decreased with RH addition. The combined kinetic analysis revealed two distinct mechanisms: (1) at the lower conversion range, the pyrolysis of the blend followed a random nucleation and three-dimensional growth mechanism, while (2) at the higher conversion range, the control mechanism transitioned into three-dimensional diffusion.

A comprehensive pyrolysis study of sorghum and reed stalk: TG/IR/MS analysis and machine learning-assisted kinetic prediction

This work focused on investigating the pyrolysis characteristics of sorghum stalk (SS) and reed stalk (RS), whose potentiality as value-added feedstocks for thermochemical conversion is largely unexplored. The experimental method, thermogravimetric-infrared-mass spectrometry, was applied to reveal the thermal decomposition process, evaluate the kinetic and thermodynamic parameters, and identify the gaseous products, which could provide fundamental data and valuable information for bioenergy utilization and optimization of reactors. The average activation energy values of SS and RS by isoconversional methods are estimated to be 185.0–210.4 kJ/mol and 192.6–197.0 kJ/mol. Though kinetic parameters, especially activation energy values, play a crucial role in understanding reaction mechanism and guiding further applications, conventional methods are time-consuming and labor-intensive. In the current work, a gradient boosting regression tree model was successfully constructed to achieve fast prediction of activation energy values with a competitive accuracy of R2 > 0.85 without repetitive experiments. In addition, the established model has showed good generalization ability in new datasets, which reveals the great potential of the machine learning approach in the pyrolysis kinetic field.

Simulation of XRD data of Ba(NdxTi(1-2x)Nbx)O3 ceramics with cubic crystal structure and (Na0.5Bi0.5)(NdyTi(1-2y)Nby)O3 ceramics with rhombohedral crystal structure by modified Arrhenius and Lorentz equations

Ba(NdxTi(1-2x)Nbx)O3 (x = 0.025, 0.05, 0.1 & 0.2) and (Na0.5Bi0.5)(NdyTi(1-2y)Nby)O3 (y = 0.0125, 0.025 & 0.05) ceramics were prepared through solid state sintering route. In the present paper X-ray diffraction (XRD) data was obtained using (Philips X-pert Pro Pan Analytical: Model PW3040/60). The XRD data was simulated using modified Arrhenius and Lorentz equation using ORIGIN 6.1 software which was proposed by us earlier. In the case of Ba(NdxTi(1-2x)Nbx)O3 ceramics the values of lattice parameter obtained using modified Arrhenius and Lorentz equations are 3.9597 Ao, 4.2534 Ao, 5.2364 Ao & 5.2690 Ao for x = 0.025, 0.05, 0.1 & 0.2 respectively. The average values of activation energy for x-ray scattering are 74.47 meV, 85.21 meV, 90.20 meV & 95.79 meV for x = 0.025, 0.05, 0.1 & 0.2 respectively. Similar simulation studies were also carried on (Na0.5Bi0.5)(NdyTi(1-2y)Nby)O3 ceramics and the results are presented in this paper.

Thermal Degradation Kinetics of Vacuum Residues in the Presence of Chrysotile Supported Ni-Ti Catalyst

For the first time, thermal decomposition of vacuum residue and a mixture of vacuum residue with binary nanocatalysts based on leached and non-leached chrysotile with applied active metals was studied using the thermogravimetry method. It is shown that the thermokinetic parameters of decomposition of vacuum residue and its mixture with binary nanocatalyst are different. The phase composition of the binary nanocatalyst was established through X-ray phase analysis (XRD): (Mg3Si2O5 (OH), NiO and Ti (SO4)2). The quantitative content of elements on the chrysotile surface was determined using X-ray fluorescence analysis: (Ni (4.88%), Ti (7.29%), Si (24.93%), Mg (7.83%), Fe (0.69%) and S (3.89%)). Using atomic emission spectral analysis, the gross quantitative content of supported metals on chrysotile was determined: Ni (4.85%) and Ti (4.86%). A transmission electron microscope showed the presence of finely dispersed particles adsorbed on the surface of and possibly inside chrysotile nanotubes with sizes ranging from 5 to 70 nm. The acidity of the nanocatalyst obtained from the leached active-metal-supported chrysotile was 267 μmol/g and the specific surface area of the nanocatalyst was 54 m2/g. The Ozawa–Flynn–Wall (OFW) method was used to calculate the kinetic parameters of the thermal degradation of vacuum residue and the mixture of vacuum residue with nanocatalysts. Using the isoconversion method, the average values of activation energies and the pre-exponential factor were calculated: 147.55 kJ/mol and 3.37·1016 min−1 for the initial vacuum residue; 118.69 kJ/mol and 1.54·1018 min−1 for the mixture of vacuum residue with nanocatalyst obtained from non-leached chrysotile with applied metals; 82.83 kJ/mol and 2.15·1019 min−1 for the mixture of vacuum residue with nanocatalyst obtained from leached chrysotile with applied metals. The kinetic parameters obtained can be used in modeling and designing the processes of thermal degradation and hydroforming of heavy hydrocarbon raw materials.