A COMPUTERIZED SYSTEM ON KINETIC ANALYSIS AND EVALUATION OF GAS/SOLID REACTIONS

The present paper presents the structure, features and functions of a computerized system on kinetic analysis and evaluation of gas/solid reactions, KinPreGSR. Kin-PreGSR is a menu driven system, can be operated with MS Windows as workbench in a PC computer. It has been developed using visual C++ with FoxPro hybrid coding technique.KinPreGSR combines the characteristics of gas/solid reactions with the kinetic models as well as mass and heat transfer equations. The database files were established for the apparent activation energies of some reduction and decomposition reactions to allow the prediction of the reaction kinetics to some extents. Outputs can be displayed using graphical or numerical forms. Examples regarding the oxide reduction and carbonate decomposition under isothermal conditions are given to show those functions.

Kinetics of synthesis of Li_4Ti_5O_(12) through solid-solid reaction

Sohd-solid reaction under low heat or low temperature is an approach to synthesize various kinds of materials that were widely used in electrochemistry field. In this paper a theoretical treatment has been presented for analyzing the mechanism of sohd-solid reaction and deriving a series of formulae to describe the variation and rate of reactions. This new model has been used in the manufacturing of spinel Li4Ti5O12. The results show that this new model works very well and will play a useful role for guiding the manufacturing of electrochemical materials.

Solid reaction mechanism of CaHPO_4·2H_2O + CaCO_3 with and without yttria

The effect of yttria on the solid reaction mechanism of a CaHPO4·2H2O ＋ CaCO3 system at different temperatures was experimentally stud-ied. The samples with and without yttria were subjected to thermogravimetric/differential scanning calorimetry measurement. The samples were heat treated at the temperatures corresponding to the peaks on the DSC spectra, and the resulted phase compositions were identified by X-ray diffraction. The transformation mechanism was deduced by comparing the phases obtained at different temperatures. The results show that the transformations at below 1073 K are not affected by yttria, but all those at above 1073 K are completely altered. The formation tem-perature of hydroxyapatite decreases by 134 K, and the decomposition temperature increases by 38 K. The polymorphous transformation of Ca3（PO4）2 from β phase to α phase increases by 47 K. The thermodynamic properties of the transformations at above 1073 K are also modi-fied by the addition of yttria; that is, the endothermal peaks are substituted by exothermal peaks.

SOLID REACTION BETWEEN PRESSLESS SINTERED Si_3N_4 SUBSTRATE AND Ti-DEPOSITED FILM

The chemical reaction at solid state between the pressless sintered Si_3N_4 substrate and Ti-de- posited film has been studied by X-ray diffraction analysis.The reaction all depends upon the temperature.It seems no reaction below 973 K:Ti_2N and Ti_5Si_3 form from 1073 to 1123 K: TiN and Ti_5Si_3 form at 1173 K,TiN and Ti_5Si_4 form at 1273 K;while the titanium film di- minishes completely.The lattice parameter of Si_3N_4 is unchanging thrioughout postannealing. This implies that the Ti atoms never dissolve into the Si_2N_4 lattice.

EFFECTS OF PARTICLE SHAPES ON THE KINETICS OF SOLID REACTIONS

In the paper, the effects of powder particle shapes on the kinetics of solid reaction (K. S. R) and errors caused by the current methods based on spherical particle models have been studied. It has been found that particle shaeps have significant effects on kinetics of the solid reaction (K. S. R). However it has now not been involved in the present kinetic equations as a factor. The ball models used by the present kinetic equation have led to great errors not only in determination of the reaction constants but also in judgement of reaction types. This is a problem that has not been much recognized and needs to be solved immediatly.

Computer prediction system on solid/solid reaction kinetics

A computer software system of kinetic predication of solid/solid reaction, KinPreSSR, was developed using Visual C ++ and FoxPro. It includes two main modules, REACTION and DIFFUSION. KinPreSSR deals with the kinetics on the diffusion in solids as well as solid/solid reactions. The REACTION module in KinPreSSR was mainly described, which has organized the commonly recognized kinetic models, parameters, and employed both numerical and graphical methods for data analyses. The proper combination between the kinetic contents and the analytical methods enables users to use KinPreSSR for the evaluation and prediction of solid/solid reactions interested. As an example to show some of functions of KinPreSSR, the kinetics analysis for the reaction between SrCO 3 and TiO 2 powders to form SrTiO 3 with a series of kinetic data from isothermal measurements was demonstrated. [

Thermochemical Heat Storage Performance in the Gas/Liquid-Solid Reactions of SrCl2 with NH3

Thermochemical heat storage is a promising technology for improving energy efficiency through the utilization of low-grade waste heat. The formation of a SrCl2 ammine complex was selected as the reaction system for the purpose of this study. Discharge characteristics were evaluated in a packed bed reactor for both the gas-solid reaction and the liquid-solid reaction. The average power of the gas-solid reaction was influenced by the pressure of the supplied ammonia gas, with greater powers being recorded at higher ammonia pressure. For the liquid-solid reaction, the obtained average power was comparable to that obtained for the gas-solid reaction at 0.2 MPa. Moreover, the lower heat transfer resistance in the reactor was observed, which was likely caused by the presence of liquid ammonia in the system. Finally, the short-term durability of the liquid-solid reaction system was demonstrated over 10 stable charge/discharge cycles.

Process intensification in gas/liquid/solid reaction in trickle bed reactors: A review

As an important form of reactors for gas/liquid/solid catalytic reaction,trickle bed reactors (TBRs) are widely applied in petroleum industry,biochemical,fine chemical and pharmaceutical industries because of their flexibility,simplicity of operation and high throughput.However,TBRs also show inefficient production and hot pots caused by non-uniform fluid distribution and incomplete wetting of the catalyst,which limit their further application in chemical industry.Also,process intensification in TBRs is necessary as the decrease in quality of processed crude oil,caused by increased exploitation depths,and more restrictive environmental regulations and emission standards for industry,caused by increased environment protection consciousness.In recent years,lots of strategies for process intensification in TBRs have been proposed to improve reaction performance to meet the current and future demands of chemical industry from the environmental and economic perspective.This article summarizes the recent progress in techniques for intensifying gas/liquid/solid reaction in TBRs and application of intensified TBRs in petroleum industry.

Single Step Solid-Solid Reaction Scheme for the Synthesis of Cobalt Sulphide-Oxide Nanoparticles in Polymer Matrix

At present, there is considerable interest in polymer-metal chalcogenides/oxides based nano-composites on account of their tunable optical, magnetic, electronic and catalytic properties. Here in, we report a simple single step approach for the in-situ synthesis of combined cobalt sulphide/cobalt oxide in polyphenylenesulphide (PPS) polymer matrix. We have illustrated the suitability of this methodology by reacting commonly available cobalt precursors with engineering thermoplastic, PPS. The cobalt precursor was homogeneously mixed with PPS in the molar ratios of 1:1, 1:5, 1:10, 1:15, respectively, followed by heating the mixtures obtained at the melting temperature of the polymer (285?C) for six hours. The resultant products were characterized by X-ray Diffractometry (XRD), Field-Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscope (HRTEM), Diffuse Reflectance Spectroscopy (DRS) technique and Fourier Transformation Infra red Spectroscopy (FTIR). Formation of mixed phases viz., sulphide and oxide of cobalt within modified PPS matrix was confirmed by XRD. The resultant nanoparticles of cobalt sulphide and cobalt oxide embedded in the PPS matrix showed crooked and chunk morphology. The optical properties of the resultant nanocomposites indicate the shift in the absorption hump due to nanoscale size effect.

Bulk Ni-Mo Composites Prepared by Solid Reaction Method and Their Hydrodeoxygenation Performance

Bulk Ni-Mo composites were prepared by a simple solid reaction method and the hydrodeoxygenation activity of samples was examined. The test results showed that the Ni-Mo catalysts possessed high catalytic activity for hydrogenation of p-cresol under mild conditions. The XRD, N_2 isothermal adsorption, NH_3-TPD characterization analyses indicated that the excellent hydrogenation performance of Ni-Mo catalysts could be attributed to their incorporated Mo metal, the developed pore system, and the strong acidity.

Nitriding of Medium Carbon Ferromanganese Alloy in Gas Solid Reaction

Nitriding process of medium carbon ferromanganese was carried out in the solid state, on lab and bench scale at temperature range 1023-1323 K using different nitrogen and hydrogen pressures. The influence of H2/N2 gas ratio, temperature and time on nitriding process of fine (-2 mm) medium carbon ferromanganese were investigated. Nitrogen content, in weight percent ranging from 2.1 to 9.7 could be obtained. The optimum temperature and time of nitriding process was found to be 1223 K and 21.6 ks respectively. The results showed that nitrogen content is mainly depending on time and temperature of nitriding process. The comparison between results of lab and bench scale, at optimum conditions, showed good coincidence. At optimum conditions;1223 K, 21.6 ks and at 2/8 of H2/N2, nitrogen content of fine medium carbon ferromanganese was 9.5%.

Approaching Ultimate Synthesis Reaction Rate of Ni-Rich Layered Cathodes for Lithium-Ion Batteries

Nickel-rich layered oxide LiNi_(x)Co_(y)MnzO_(2)(NCM,x+y+z=1)is the most promising cathode material for high-energy lithium-ion batteries.However,conventional synthesis methods are limited by the slow heating rate,sluggish reaction dynamics,high energy consumption,and long reaction time.To overcome these chal-lenges,we first employed a high-temperature shock(HTS)strategy for fast synthesis of the NCM,and the approaching ultimate reaction rate of solid phase transition is deeply investigated for the first time.In the HTS process,ultrafast average reaction rate of phase transition from Ni_(0.6)Co_(0.2)Mn_(0.2)(OH)_(2) to Li-containing oxides is 66.7(%s^(-1)),that is,taking only 1.5 s.An ultrahigh heating rate leads to fast reaction kinetics,which induces the rapid phase transition of NCM cathodes.The HTS-synthesized nickel-rich layered oxides perform good cycling performances(94%for NCM523,94%for NCM622,and 80%for NCM811 after 200 cycles at 4.3 V).These findings might also assist to pave the way for preparing effectively Ni-rich layered oxides for lithium-ion batteries.

Oxide coating mechanism during fluidized bed reduction: solid-state reaction characteristics between iron ore particles and MgO

Experiments on the solid-state reaction between iron ore particles and MgO were performed to investigate the coating mechanism of MgO on the iron ore particles＇ surface during fluidized bed reduction. MgO powders and iron ore particles were mixed and compressed into briquettes and, subsequently, roasted at different temperatures and for different time periods. A Mg-containing layer was observed on the outer edge of the iron ore particles when the roasting temperature was greater than 1173 K. The concentration of Fe in the Mg-containing layer was evenly distributed and was approximately 10wt%, regardless of the temperature change. Boundary layers of Mg and Fe were observed outside of the iron ore particles. The change in concentration of Fe in the boundary layers was simulated using a gas–solid diffusion model, and the diffusion coefficients of Fe and Mg in these layers at different temperatures were calculated. The diffusion activation energies of Fe and Mg in the boundary layers in these experiments were evaluated to be approximately 176 and 172 k J/mol, respectively.

Solid state interfacial reactions in electrodeposited Ni/Sn couples

Ni/Sn couples, prepared by sequentially electroplating Ni layers and Sn layers on metallized Si wafers, were employed to study the microstructures and growth kinetics of Ni-Sn intermediate phases, when the Ni/Sn couples were aged at room temperature or armealed at temperatures from 150 to 225℃ for various times. The results show that the NiSn phase and Ni3Sn4 phase are formed, respectively, in the aged couples and annealed couples. The Ni3Sn4 layer is continuously distributed between the Ni and Sn sides in the annealed Ni/Sn couples. The Ni3Sn4 growth follows parabolic growth kinetics with an apparent activation energy of 39.0 kJ/mol.

FORMATION OF MANGANESE SILICIDE THIN FILMS BY SOLID PHASE REACTION

Manganese silicide MnSi_(2-x) thin films have been prepared on n-type siliconsubstrates through solid phase reaction. The heterostructures were analyzed by X-ray diffraction,Rutherford backscattering spectroscopy, Fourier transform infrared transmittance spectroscopy andthe four-point probe technique. The results show that two manganese silicides have been formedsequentially via the reaction of thin layer Mn with Si substrate at different irradiation annealingstages, i.e., MnSi at 450 deg C and MnSi_(1.73) at 550 deg C. MnSi_(1.73) phase exhibits preferredgrowth after irradiation with infrared. In situ four-point probe measurements of sheet resistanceduring infrared irradiation annealing show that nucleation of MnSi and phase transformation of MnSito MaSi_(1.73) occur at 410 deg C and 530 deg C, respectively; the MnSi phase shows metallicbehavior, while MnSi_(1.73) exhibits semiconducting behavior. Characteristic phonon bands ofMnSi_(2-x) silicides, which can be used for phase identification along with conventional XRDtechniques, have been observed by FTIR spectroscopy.

Solid State Reaction Yielding a Mineral Utilizing Silica Obtained from an Agricultural Waste

Wollastonite, a mineral of wide industrial applications was synthesised from rice husk ash silica and limestone. A number of raw batches consisting of these starting materials, in 1:1 molar ratio, were heat treated to produce it through solid state reaction from 900℃ to 1300℃. The conducted reaction was monitored by XRD step by step. Amount of Wollastonite formed at every temperature was also studied to some extent. Analyses of the obtained data indicated that the target mineral formation was quite effective and almost proportional to a rise in temperature up to 1200℃. The results from both, XRD and chemical analysis were found in fair agreement with one another

Reaction mechanisms for 0.5Li_2MnO_3 ·0.5LiMn_(0.5)Ni_(0.5)O_2 precursor prepared by low-heating solid state reaction

Lithium-excess manganese layered oxides, which are commonly described in chemical formula 0.5Li2MnO3·0.5LiMn0.5Ni0.5O2, were prepared by low-heating solid state reaction. The reaction mechanisms of synthesizing precursors, the decomposition mechanism, and intermediate materials in calcination were investigated by means of Fourier transform infrared spectroscopy （FT-IR）, X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, thermogravimetric analysis （TGA）, and differential scanning calorimetry （DSC）. The major diffraction patterns of 0.5Li2MnO3·0.5LiMn0.5Ni0.5O2 powder calcinated at 720℃ for 15 h are indexed to the hexagonal structure with a space group of R3m, and the clear splits of doublets at （006）/（102） and （108）/（110） indicate that the sample adopts a well-layered structure. FESEM images show that the size of the agglomerated particles of the sample ranges from 100 to 300 nm.

Reaction Process of Chromium Slag Reduced by Industrial Waste in Solid Phase

M, a particular industrial waste, was selected to detoxify chromium slag at a high temperature. The carbon remaining in M reduced Cr （ Ⅳ ） of Na2 CrO4 borne in the chromium slag to Cr （ Ⅲ ） in the solid phase reaction, and its thermodynamics and kinetics were studied. The reduction process of Na2CrO4 by carbon produced CO, whiCh＇was endothermic. Under the experimental condition, the apparent activation energy was 4. 41 kJ·mol^-1 , the＇apparent order of reaction for Na2 CrO4 was equal to one, and the partial pressure of CO was only 0.22 Pa at 1 330℃.

Synthesis of Mesoporous Chromium Aluminophosphate (CrAlPO) via Solid State Reaction at Low Temperature

Mesoporous chromium aluminophosphate （CrAIPO） was successfully synthesized via solid state reaction （SSR） route at low temperature in the presence of a cationic surfactant cetyltrimethyl ammonium bromide （CTAB） and inorganic sources such as A1C13 · 6H20, CrCI3 · 6H20 and NaH2PO4 · 2H20. Characterizations by means of powder X-ray diffraction （XRD）, N2 adsorption- desorption, high resolution transmission electron microscopy （HR-TEM）, scanning electron micrography （SEM）, energy dispersion spectroscopy （EDS）, thermo-gravimetry （TG）, Fourier transform infrared spectroscopy （FT-IR）, and ultraviolet visible light spectroscopy （UV-Vis） were carried out to understand both the pore characteristics and electron transition route of these obtained materials. The experimental results show that the meso-CrA1PO materials with various Cr/A1 molar ratios possess a mesostructure and a specific surface area of 193 to 310 m2/g corresponding to an average pore size of 5.5 to 2.2 rim, respectively. The maxium content of Cr in meso-CrA1PO materials synthesized via SSR route can achieve 16.7wt%, being significantly higher than that of the meso-CrA1PO prepared via a conventional sol-gel route. Meanwhile, the formation mechanism of the meso-CrA1PO was also proposed.

Thermal stability of Mg_2 Si epitaxial film formed on Si(111) substrate by solid phase reaction

A single crystalline Mg2Si film was formed by solid phase reaction （SPR） of a Si（111） substrate with an Mg overlayer capped with an oxide layer（s）,which was enhanced by post annealing from room temperature to 100℃ in a molecular beam epitaxy （MBE） system.The thermal stability of the Mg2Si film was then systematically investigated by post annealing in an oxygen-radical ambient at 300℃,450℃ and 650℃,respectively.The Mg2Si film stayed stable until the annealing temperature reached 450℃ then it transformed into amorphous MgOx attributed to the decomposition of Mg2Si and the oxidization of dissociated Mg.