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This study investigates the pyrolysis kinetics behaviour and temperature effects on biochar yield and properties during pyrolysis. The kinetic study of biomass was performed using a thermogravimetric analyser at dynamic heating rates (10, 30, and 50 °C min−1) in an inert atmosphere. The kinetic parameters were estimated using Kissinger-Akahira-Sunose (KAS), Distributed Activation Energy Model (DAEM), and Vyazovkin model (VZ). The pyrolysis experiment was performed in a stainless steel semi-batch reactor at 400, 600, and 900 °C, 10 oC min-1 heating rate, 45 min holding time and 100 mL min−1 nitrogen gas flow rate. The produced biochar was characterised using proximate analysis, ultimate analysis, heating value, bulk density, BET surface area analyser, TGA, FTIR, and FE-SEM analysis. The physicochemical results support the candidacy of biomass for biochar and fuel production. Further, the kinetic analysis of MWS using KAS, DAEM, and VZ was found to be 233.39, 238.11, and 224.74 kJ mol−1, respectively. The experimental results reveal that higher temperatures (600 and 900 °C) generally reduce biochar yield (19 %) due to increased devolatilization but enhance the biochar's surface area (17 %) and carbon content (4.84 %). The characterisation results of biochar confirmed higher carbon content (76.02 wt. %), HHV (36.97 MJ kg−1), and significant oxygen content (22.01 %) at 900 °C. Also, the thermal profile and surface morphology of the biochar suggest that biochar derived at 600 and 900 °C can be used for carbon-based applications, whereas biochar derived at 400 °C can be used for soil amendment or fertiliser applications.

The current study explored the bioenergy potential of waste miscanthus grass (WMG). The kinetic study of WMG was evaluated via two model-free methods, in a thermogravimetric analyzer (TGA), at dynamic heating rates under an inert ambiance. The pyrolysis was performed in a semi-batch fixed bed reactor at 500 oC, 80 oC min heating rate, and 1 mm particle size. The evolution of hot vapours during pyrolysis was explored using a TGA-FTIR analyzer. Finally, the bio-oil and biochar were characterized by their physicochemical properties. The kinetic results established that WMG followed a multi-step decomposition process, and the average activation energy gained from KAS and ST was found to be 197.66 and 179.64 kJ mol-1, respectively. TGA-FTIR study revealed the foremost release of carbon dioxide (28.22%), followed by a carbonyl (25.40%), and ether (19.12%). Further, the pyrolysis of WMG yielded 29.32 wt% of bio-oil at the optimized condition whereas, physicochemical results of bio-oil established; 65.16% carbon content, 26.16 MJ kg-1 HHV, 34.15 cP viscosity, and 812 kg m-3 density. GC-MS study of bio-oil confirmed the maximal release of hydrocarbons and phenols. Finally, characterization results of miscanthus grass biochar (MGB) demonstrated an excellent feedstock for industrial and domestic applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Here we developed a continuous flow microreactor system to synthesis N-benzoylpiperazine, which is an important intermediate of novel nootropic Sunifiram. And the kinetics of the condensation amidation of piperazine and benzoic acid using HATU as coupling reagent was revealed in microreactor. A kinetic model was established, all the reactions kinetics parameters, including the reaction order of each reactant, rate constants, pre-exponential factors and activation energies were acquired. With this model the selectivity vs. reaction temperature/molar flow ratio were obtained to help understand this kind of reaction and further optimize operating conditions. Under the condition of using equivalent piperazine, 95.6% of selectivity and 91.2% of yield were obtained in microreactor with 50 s. To further expand the scope of carboxylic acid, cyclopropanecarboxylic acid was tried as acylating agent, and 92.8% of selectivity and 86.1% of yield were obtained in microreactor. [ABSTRACT FROM AUTHOR]

In this paper, the kinetics of acylation reaction of o‐phenylenediamine/p‐phenylenediamine and benzoic anhydride were determined in microreactors, respectively. A kinetic model was established, all kinetic parameters including reaction orders, reaction rate constants, pre‐exponential factors, and activation energies were acquired. Validation experiments showed experimental data fit well with calculated data at different reactant concentrations and residence times. The comparisons of the reaction rate constants and activation energies were summarized to show the difference of chemical reactivities of phenylenediamines. According to the calculation of the kinetic model, the optimized reaction conditions were listed to meet the monoacylation selectivity equal to 97.0%. [ABSTRACT FROM AUTHOR]

• The iron-rich copper ore are evidenced to be a very suitable OC for CLC of methane. • The copper ore OC represented high methane conversion, CO 2 selectivity and stability during the long-term CLC testing. • The overall reduction of the ore OC is controlled by the nucleation-growth and diffusion-controlled mechanisms. Chemical looping combustion (CLC) has been considered as a revolutionary combustion technology for low-energy capture of CO 2. In this paper, an iron-rich copper ore, mainly containing CuO, CuFe 2 O 4 , SiO 2 and Al 2 O 3 , was used as an inexpensive oxygen carrier (OC) for chemical looping combustion of methane. The activity for methane oxidation, the stability during long-term CLC testing and the structural evolution after redox cycling were systematically investigated. In addition, kinetic study via a thermogravimetric analyzer (TGA) method was also performed on the recycled oxygen carrier to understand the reduction mechanism. The results show that the iron-rich copper ore OC can oxidize methane with very high selectivity (CO 2 selectivity > 95%), conversion (CH 4 conversion = 80%) and stability in the successive CLC process. No obvious sintering is observed after 30 redox cycling. This can be attributed to the enhanced diffusion of different components (Cu, Fe, Si and Al) in the redox process, which could improve the interaction between the active components (CuFe 2 O 4 and CuO) and the support components (SiO 2 and Al 2 O 3). The kinetic study shows that a nucleation-growth model and a diffusion-controlled model can be successfully adapted to depict the reduction of CuO and Fe 2 O 3 in the copper ore OC, respectively. The activation energies for CuO and Fe 2 O 3 reductions are 56.49 and 109.56 kJ/mol, respectively, which are similar with that for the synthetic CuO-based or CuFe 2 O 4 -based OCs. This work fully demonstrates the feasibility of using iron-rich copper concentrate as a lower cost OC for the CLC system. [ABSTRACT FROM AUTHOR]

Abstract: This work reports bioconversion of unsaturated free fatty acids present in soapstock, inherent waste of edible oil manufacture, to the epoxidized fatty acids using Candida rugose lipase in a micro-reactor. Activation energy of the epoxidation reaction was found to be 32.27 kJ mol−1 while the enzyme deactivation was observed at higher temperature than 35 °C with an activation energy of 91.18 kJ mol−1. The low hydrodynamic retention time in the micro-reactor provides a proper condition to measure of initial rates of the enzymatic reaction. The kinetics study was performed at ten different molar ratios of H2O2/C=C, and constants of the Ping-Pong bi bi model were estimated as follows: the maximum specific enzyme activity (Vmax) of 1.453 × 105 mM min−1 genzyme−1, dissociation constant for enzyme-FFA complex (KA) of 58.83 mM genzyme−1, Michaelis constant for FFAs (KmA) of 1.382 × 103 mM genzyme−1, Michaelis constant for hydrogen peroxide (KmB) of 3.279 × 106 mM genzyme−1, and the deactivation constant due to hydrogen peroxide (KIB) of 59.25 mM genzyme−1. The cross-linked enzyme aggregate technology provided a simple method to produce the robust biocatalyst for this bioconversion where more than 89% of original activity was maintained after 9 cycles in the micro-reactor.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Hydrogen, as chain transfer agent, effects on kinetic of propylene polymerization; consequently variation of hydrogen concentration leads to change final product properties and also activates site of used catalyst. This phenomenon is one of the most important process variables is to adjust the final product properties and optimize the operating conditions. This work has attempted to present a mathematical model that cable to calculate the most important indices of end used product, such as melt flow index, number and weight average molecular weight and poly dispersity index. The model can predict profile polymerization rates determining important kinetic parameters such as the activation energy, lumped deactivation reaction initial reaction rate and deactivation constant. The mathematical model was implemented in Matlab/Simulink environment for slurry polymerization in laboratory scale. The modeling approach is based on polymer moment balance method in the slurry semi-batch reactor. In addition, in this work have provided a model that calculating fraction activated sites catalyst via hydrogen concentration. The model was validated by experimental data from lab scale, reactor. The experimental and model outputs were compared; consequently, the errors were within acceptable range. [ABSTRACT FROM AUTHOR]

Air injection has been used for decades as an enhanced oil recovery method. An oxidation kinetics study is important for the application of air injection. Low-temperature oxidation is more feasible in light oil reservoirs. Although an experiment using a small batch reactor has been conducted before, the reaction order with respect to the oxygen partial pressure was not well studied. The authors use a small batch reactor to study the effect of temperature and pressure on the oxygen consumption rate of the Wolfcamp light oil. The reaction order, the activation energy, and Arrhenius constant are calculated. [ABSTRACT FROM AUTHOR]

Hydrogen-deficient and oxygen-rich biomass result in low hydrocarbon production during pyrolysis. This work aims to enhance aromatics in bio-oil through ex-situ catalytic co-pyrolysis of poplar sawdust (PS) and polypropylene (PP) over Fe-Ni/ZSM-5 and gain an understanding of the synergistic pyrolysis performance. The results showed that adding PP improved the comprehensive pyrolysis performance of the PS and PP blends. The deviation between the experimental and calculated mass loss of the blends confirmed the interaction between PS and PP, with a more positive synergistic effect at a biomass/plastic mass ratio of 3:2. The average activation energy of PP was 211.6 kJ·mol−1, which is 28.2 % higher than that of PS. As the proportion of PP increases, the activation energy required for the blends increases. The established artificial neural network model accurately predicts the mass loss of the blends (R2 ≥ 0.999) by providing the mixing ratio, heating rate, and temperature. The addition of hydrogen-rich feedstock increased aromatic yield in the volatile products, indicating the positive synergy between PS and PP during catalytic co-pyrolysis over Fe-Ni/ZSM-5. As the targeted products among the aromatics, the total yields of benzene, toluene, and xylene ranged from 58.43 to 251.03 mg·g−1 in the PS and PP blends, respectively. [Display omitted] ● Ex-situ catalytic co-pyrolysis of PS and PP was performed over Fe-Ni/ZSM-5. ● The addition of PP improves the comprehensive pyrolysis performance of the blends. ● Artificial neural network model accurately predicted mass loss. ● Synergistic effect leads to improved yields of aromatics in PS and PP blends. [ABSTRACT FROM AUTHOR]

Alkynated and azidated octadecane, synthesized from 9-octadecene, were used as model compounds for alkynated and azidated vegetable oils to study the kinetics of thermal Huisgen 1,3-dipolar cycloaddition. Alkyne and azide groups of alkynated and azidated octadecane possess low reactivity as they are branched in the middle of an 18-carbon chain. Reaction kinetics was studied by GPC, 1H NMR, and DSC. Detailed kinetic analysis revealed that the reaction of alkynated and azidated octadecane required 24 h to reach 90% conversion at 100°C. The activation energy of the reaction is 55 kJ/mol. [ABSTRACT FROM AUTHOR]

Abstract: The kinetic and thermodynamic characteristics of adsorption of Cr (III) on IRN77 cation-exchange resin was investigated in the present study. Cr (III) sorption on cation-exchange resin IRN77 was studied as a function of time and temperature. The temperature was found to have a positive effect on film and particle diffusion processes. The activation energy was calculated using Arrhenius equation based on the rate constants and indicated that the activation energy of the particle diffusion process was higher than that of the film diffusion process. The film diffusion equation was well-fitted with a correlation coefficient over 0.99. The results showed that the film diffusion process was the rate-limiting step during Cr (III) sorption process. After the rate constants of adsorption isotherm of Cr (III) obtained from the Langmuir equation, the thermodynamic parameters ΔS θ, ΔH θ and ΔG θ were further calculated using the Eyring equation. The ΔS θ and ΔH θ were found to be -128.07J/mol·K and 42.98kJ/mol, respectively. The ΔG θ at temperature 298K, 313K and 328K were 81.14, 83.07 and 84.99kJ/mol, respectively. The thermodynamic characteristics revealed that the mechanism of Cr (III) sorption was endothermic and the entropy-driving ion exchange. [Copyright &y& Elsevier]

In this study, a thorough exploration was performed on the mechanism of microwave enhancement in the treatment of cyanide tailings by the microwave chlorination heat treatment process. The improvement rate of the dielectric properties of tailing materials is rapid in the high temperature range (673–1173 K), which indicates that cyanide tailings have favorable microwave- absorbing performance. Under the action of iron oxide, the loss tangent of raw materials increased from 0.0364 to 0.1914. The heating efficiency improved significantly, from 6.73 K/min to 41.667 K/min. The kinetics experiment was performed on tailings in the two different roasting process. Compared with conventional roasting, the activation energy of the chlorination reaction of gold under the microwave roasting decreased by 32.47%. The work provides sound references for promoting the industrial application of microwave chlorination roasting on cyanide tailings. [Display omitted] • Determination of the microwave absorption properties of cyanide tailings for the first time. • The test of the dielectric properties in roasting process demonstrated the positive effects of microwave heating. • The activation energy of the chlorination reaction of gold under microwave roasting decreases by 32.47%. [ABSTRACT FROM AUTHOR]

• SPM could be efficiently decomposed by thermally activated PDS technology. • The kinetics and mechanism of SPM oxidation was investigated. • SPM degradation was significantly influenced by operating conditions. • Intermediates were identified and proved to have no acute toxicity. In recent years, antibiotic residues are frequently detected worldwide that has posed a serious threat to drinking water and increased the risk of bacterial resistance. Sulfate radical (SO 4 •−)-based advanced oxidation has been regarded as an effective technology for refractory organic pollutants treatment. In this study, the degradation kinetics and mechanism of spiramycin (SPM) under thermally activated peroxydisulfate (PDS) oxidation process in aqueous solution were investigated for the first time. The results indicated that the degradation rate of SPM could be expressed as the kinetic rate equation -d[SPM]/d t =(2.96 × 10−2 mM0 min−1)[SPM]0[SPM]1 within limited experimental conditions utilized here (i.e., 50 °C, pH 7, SPM 0.01–0.05 mM, and K 2 S 2 O 8 1.0–2.72 mM). The apparent activation energy of 83.27 kJ·mol−1 was calculated by Arrhenius equation. The SPM degradation rate decreased with the increase of pH value. The SO 4 •− and hydroxyl radical (•OH) were proved to be the dominant reactive species, but the contribution of SO 4 •− on the SPM oxidation gradually decreased with the increase of pH value. The presence of humic acid (HA) and inorganic anions negatively affected the SPM degradation. To investigate the possible reaction pathways of SPM under thermally activated PDS system, HPLC/ESI-QqQMS was employed to identify the intermediate products. In addition, the acute toxicity evaluated by Vibrio fischeri showed that the oxidation byproducts of SPM were not antibacterial. In summary, this study confirmed that the thermally activated PDS technology could be a promising, efficient, and environmental-friendly approach for removing SPM in aqueous solution. [ABSTRACT FROM AUTHOR]

Co-combustion of biomass offers a great potential to reduce CO 2 emissions but rarely mentioned co-combustion behavior of pelletized coal-biomass mixtures and inconclusive results based on single determinants formed obstacle for industrial application. In this study, ignition and flame characteristics, reaction and kinetic parameters and pollutant generation path were comprehensively investigated. Intrinsic combustion experiments were carried with the gas phase maintaining at room temperature in a concentrating photothermal reactor at heating rate over 200 °C/s. Same "homogeneous" ignition was evidenced while advanced devolatilization but more intense slagging behaviors were identified with the increase of biomass proportion. With the biomass proportion increased from 0% to 40%, the activation energies during devolatilization to ignition decreased non-linearly from 47.44 kJ/mol to 8.03 kJ/mol, indicating the existence of synergistic effect. CO exhibited relative high generation rates and the generation rate increased with the biomass content. Three fitted CO peaks were identified during co-combustion, which were contributed by devolatilization of coal and biomass, and combustion of char, respectively. First increased and then decreased NO emission with the increase of biomass proportion was evidenced for the higher N content in biomass but enhanced reduction by char and NH radicals with higher biomass proportion. • Co-combustion behaviors (ignition, slagging, kinetic and pollutant) were studied • The Ea decreased non-linearly from 47.44 kJ/mol to 8.03 kJ/mol with biomass addition • CO exhibited high intrinsic generation rate and biomass formed an independent CO peak • Biomass enhanced primary fuel-N emission and NO reduction by char and NH radical • Synthetic effects were proved by combustion characteristics and kinetic analysis [ABSTRACT FROM AUTHOR]

• The kinetics of m -phenylenediamine monoacylation was studied in a microreactor. • The possible reaction mechanism was postulated from the kinetics study. • The accuracy of the kinetic model was proved by validation experiments. • The effect of each parameter on selectivity was studied by the kinetic model. Monoacylated symmetrical diamines are building blocks or intermediates of several well-established drugs. However, for the symmetrical diamines, the two amine groups located in a similar chemical environment make the selective monoacylation rather difficult and no kinetics study has ever been reported before. To comprehend this kind of reaction more deeply, a continuous flow microfluidic system was developed to evaluate the reaction kinetics of m -phenylenediamine and benzoic anhydride. At first, the reaction order of each reactant, pre-exponential factors and activation energies were determined in turn. The possible reaction mechanism was postulated from the reaction order. Then, a series of validation experiments were designed to show the accuracy and the applied range (concentration and temperature) of the kinetic model. Next, to obtain a controlled selectivity, the effects of initial concentration, reaction temperature and molar ratio on the selectivity were investigated through the model simulation. In the end, under the conditions optimized by the kinetic model, 96.9% selectivity and 92.5% yield were obtained in the microreactor. [ABSTRACT FROM AUTHOR]

• Renewable non-edible seeds were used for pyrolysis. • Seven models were used to determine kinetic parameters. • Kinetic reaction data showed good agreement with experimental data. • VZ and DAEM methods produce minimal error compared with others. The present study addressed the kinetics characteristics and pyrolysis behaviour of waste biomass Azadirachta indica (NM) and Phyllanthus emblica kernel (AM) in a thermogravimetric analyzer. Six model-free techniques such as Kissinger-Akahira-Sunose, Distributed Activation Energy Model, Friedman, Coats-Redfern, Ozawa-Flynn-Wall, Vyazovkin and Criado method were employed to evaluate the kinetic parameters at five varying heating rates (10–50 °C min−1). The physicochemical inspection directed that both the biomass had excellent prospects to produce energy and finest chemicals. FTIR study pointed strong evidence of moisture, protein, acid, and aromatics. The average apparent activation energy was found to be 176.66, 193.67, 196.06, 177.32 and 204.23 kJ mol−1 for NM and 184.77, 195.10, 189.95, 186.46, 184.57 kJ mol−1 for AM for KAS, OFW, FM, DAEM and VZ respectively. Further, master plot and thermodynamic study of AM and NM revealed that pyrolysis went through various reaction mechanisms at the time of pyrolysis. [ABSTRACT FROM AUTHOR]