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Journal of Thermal Analysis and Calorimetry
Authors: Dumitru Oancea, Valentin Munteanu, Domnina Razus, and Maria Mitu

temperatures, for the stoichiometric propane/air mixture occurring in isothermal conditions on platinum wire. The results are rationalized on the basis of a simple kinetic model implying the multiplication of the surface active intermediates and resulting in a

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of non-isothermal and isothermal kinetic models simulations led to a beneficial kinetic model of thermal decomposition to predict the thermal hazard of LOPs. The chosen approach was to establish an effective model of the thermal decomposition that

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types of active sites on the catalyst surface permits effective kinetic modeling for a given set of operating conditions. Olefin polymerization kinetics has been investigated for a wide variety of polymerization systems, but in most cases, the

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also more subject to steric hindrance compared with water [ 28 ]. These effects resulted in the optimum amount of water being higher than that for methanol. Conclusions A kinetic model describing PDH and catalyst deactivation

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temperature than iron-based catalysts [ 7 ]. Co-based FTS is further favored since the reaction is little affected by water [ 8 – 10 ]. The development of a kinetic model of FTS is important for the simulation, design, and optimization of commercial FT

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Abstract  

The reactivity in steam of five different types of solid fuels (two coals, two types of biomass and a petcoke) has been studied. The fuel chars were obtained by pyrolysis in a fixed-bed reactor at a temperature of 1373 K for 30 min. The gasification tests were carried out by thermogravimetric analysis (TG) at different temperatures and steam concentrations. The reactivity study was conducted in the kinetically controlled regime and three representative gas-solid models, volumetric model (VM), grain model (GM) and random pore model (RPM), were applied in order to describe the reactive behaviour of the chars during steam gasification. The kinetic parameters of these models were derived and the ability of the models to predict conversion and char reactivity during gasification was assessed. The best model for describing the behaviour of the samples was the RPM. The effect of the partial pressure of steam in gasification was studied, and the reaction order with respect to steam was determined. The reactivity of the chars was compared by means of a reactivity index. Biomass exhibited a higher reactivity than coals and petcoke. However, significant differences in reactivity were observed between the two types of biomass used, which could be due to catalytic effects.

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Abstract  

The kinetic of the reaction ilmenite with sulphuric acid was studied using non-adiabatic and non-isothermic calorimetric device system. The kinetic model based on interphase surface and kinetic models found in literature which are usually applied were tested. The best agreement between experimental and calculated values was found with model based on first order of reaction and model of contracting volume.

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Abstract  

Thermogravimetric analysis (TG) was used in this work to study the degradation kinetics of industrial PVC plastisols. In order to model the pyrolitic degradation of plastisols in nitrogen, a kinetic model based on phenomenological considerations was developed. Two different processes were observed during the first degradation stage. The model parameters, such as activation energies and pseudo orders of reaction, were calculated using a non-linear regression analysis. The model developed was able to describe the degradation behaviour both in isothermal and in dynamic modes. The results of such analysis were applied to obtain long-term data from short-term experiments as an engineering approach to evaluate the thermal resistance of plastisols.

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Abstract  

The non-isothermal data given by TG curves for poly(3-hydroxybutyrate) (PHB) were studied in order to obtain a consistent kinetic model that better represents the PHB thermal decomposition. Thus, data obtained from the dynamic TG curves were suitably managed in order to obtain the Arrhenius kinetic parameter E according to the isoconversional F-W-O method. Once the E parameters is found, a suitable logA and kinetic model (f(α)) could be calculated. Hence, the kinetic triplet (E±SD, logA±SD and f(α)) obtained for the thermal decomposition of PHB under non-isothermal conditions was E=152±4 kJ mol−1, logA=14.1±0.2 s−1 for the kinetic model, and the autocatalytic model function was: f(α)=αm(1−α)n0.42(1−α)0.56.

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Abstract  

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is a typical highly energetic material that has been widely used in national defense industries since the 1940s. The aim of this study was to establish a reaction kinetic model on thermal decomposition properties via differential scanning calorimetry (DSC) by well-known kinetic equations and kinetic model simulation. Furthermore, the aim also was to compare kinetic algorithms for thermal decomposition energy parameters under various conditions. Experimental results highly depended on the reliability of the kinetic concept applied, which is essentially defined by the proper choice of a mathematical model of a reaction. In addition, the correctness of the methods is used for kinetics evaluation.

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