Values Of Reaction Rate Research Articles

The development of reaction kinetics for CO2 absorption into novel solvent systems: Frustrated Lewis pairs (FLPs)

Frustrated Lewis Pairs (FLPs) comprising sterically hindered Lewis acids and bases were developed and kinetic parameters for the homogenous reaction between CO2 and FLP dissolved in bromobenzene were obtained by using the stopped-flow method for the first time in the scope of this work. As a sterically hindered Lewis acid chlorobis(pentafluorophenyl)borane, B(C6F5)2Cl and as a sterically hindered Lewis base tri-tert-butylphosphine, tBu3P were analyzed. Experiments were performed by varying FLP concentration in bromobenzene medium over the range of 0.02–0.035 M and for a temperature range of 298–313 K. Modified termolecular reaction mechanism was used to analyse the experimental kinetic data. Then, the relatively low reaction rate of FLP: bromobenzene system was enhanced significantly by blending constant amounts of promoters, such as amino ethyl piperazine (AEPZ), carbonic anhydrase (CA) and 1-ethyl-3-methyl imidazolium bis (trifluoromethyl sulfonyl) imide ([emim][Tf2N]). The intrinsic reaction rates of promoted solvents were measured in a stopped-flow technique over a temperature range of 293–323 K. The empirical power law reaction orders with respect to FLP concentration were found to be between 1.0 and 2.0 at various temperatures. Additionally, at these operating conditions, the promoting effects of AEPZ, CA, and [emim][Tf2N] results in a higher reaction rate and lower activation energy values.

Modelling Heat Loss Effects in the Large Eddy Simulation of a Lean Swirl-Stabilised Flame

The flame in a gas turbine model combustor close to blow-off is studied using large eddy simulation with the objective of investigating the sensitivity of including different heat loss effects within the modelling. A presumed joint probability density function approach based on the mixture fraction and progress variable with unstrained flamelets is used. The normalised enthalpy is included in the probability density function to account for heat loss within the flame. Two simulations are presented that use fixed temperature boundary conditions, and use adiabatic and non-adiabatic formulations of the combustion model. The results are compared against the previous fully adiabatic case and experimental data. The statistics for the simulations are similar to the results obtained from the fully adiabatic case. Improved statistics are obtained for the temperature in the near-wall regions. The non-adiabatic flamelet case shows the average reaction rate values at the flame root are approximately 50% smaller in comparison to the adiabatic flamelet cases. This causes the lift-off height to be overestimated. The time series of the lift-off height and the volume integrated heat release rate show that including non-adiabatic flamelets causes the flame to be highly unstable. A higher enthalpy deficit is seen in the near-field regions when the flame root is not present and experiencing some lift-off, suggesting that the flame is more dynamic when including heat loss.

Application of the New 400 MHz High-Temperature Superconducting (HTS) Power-Driven Magnet NMR Technology for Online Reaction Monitoring: Proof of Concept with a Ring-Closing Metathesis (RCM) Reaction

Monitoring chemical reactions by nuclear magnetic resonance (NMR) is an established and valuable approach for process understanding, robustness, scalability, and control in the pharmaceutical industry. Understanding speciation, reaction rates, and reaction completion times provides information on how to improve a chemical process, leading to increased quality and quantity of the desired product. An important consideration for online monitoring is to have an NMR instrument colocated with a chemical reactor. The standard commercial medium- to high-field NMR instruments are normally installed in isolated locations due to facility and safety restrictions. Low-field NMR instruments suffer from low resolution and sensitivity, requiring chemometric analysis for medium to complex chemical structures. Reactions are typically monitored using NMR tubes and deuterated solvents. Therefore, reaction analysis may not provide the same kinetic information as when the reaction occurs in a reactor at a larger scale. To overcome these factors, we have tested a prototype NMR instrument with a 400 MHz cryogen-free power-driven high-temperature superconducting (HTS) magnet installed in a chemistry laboratory fume hood for online monitoring of reactions. We have tested the HTS NMR system with a ring-closing metathesis (RCM) reaction of diethyl diallyl malonate with Grubbs 2nd Gen catalyst in a reactor with a protonated solvent. The reaction was monitored online with a Bruker InsightMR flow cell, and data was acquired in automation, yielding a kinetic time-course of the transformation and reaction rate values. This work demonstrates that NMR instruments with HTS magnets can be integrated into the chemistry laboratory with other equipment and are a valuable tool for reaction monitoring under typical reaction conditions and in protonated solvents.

CaCO3 decomposition for calcium-looping applications: Kinetic modeling in a fixed-bed reactor

Calcium looping can be used in various environmental applications such as post-combustion CO2 capture, sorption-enhanced reforming and thermochemical energy storage. The calcination reaction mechanism and the effect of CO2 partial pressure have not been fully clarified yet justifying further efforts; this work focuses on kinetic modeling of the reaction. Herein, calcination kinetics of limestone were studied experimentally in a fixed-bed reactor, and theoretically using different models previously reported in the literature. The Uniform Conversion Model (UCM) and the Changing Grain Model (CGM) described better the conversion-time data than the Random Pore Model (RPM). A Langmuir-Hinshelwood mechanistic model, which included the decomposition of CaCO3, the desorption of CO2 and the CaO* relaxation fitted well the reaction rate values leading to an activation energy of 210 kJ/mol and the pre-exponential factor equal to 18,860 kmol/(m2 s). The model was validated by predicting adequately the decomposition rates measured by other authors under different conditions.

Development of novel nano-hydroxyapatite doped with silver as effective catalysts for carbon monoxide oxidation

A series of novel silver-containing catalysts were synthesized, characterized by X-ray diffraction, infrared spectroscopy, scanning and transmission electron microscopy, N2 adsorption-desorption isotherms, thermogravimetric analysis and then tested for the oxidation of carbon monoxide (CO). The microwave-hydrothermal method was a useful synthesis pathway to structurally incorporate low amounts of silver (2.5–5.0 atomic percentage) to hydroxyapatite (HA) lattice, preserving the crystalline structure of the HA. Specific surface area and particle size (diameter) of the obtained materials were about 52–55 m2/g and 19–47 nm, respectively. Silver-catalysts showed higher catalytic activities than the unmodified HA sample at temperatures between 600 and 850 °C. The best catalytic results were achieved at around 700–800 °C with silver-containing HA samples. However, due to the significant decrease in the crystallinity of the materials exposed to 800 °C; then, 700 °C was established as the best thermal condition for producing CO2 and preserving the HA crystalline structure.Furthermore, cyclic tests demonstrated that silver-containing HA catalysts perform CO oxidation for 3 h through several consecutive catalytic tests at 700 °C without losing neither their activity nor their structural properties, evidencing their high thermal stability under the CO-O2 atmosphere. Thus, the highest reaction rate values (rCO2) were obtained with HA containing 2.5% of silver at 700 °C during the five cycles performed, positioning it as a promissory catalyst with high activity during the CO oxidation at high temperatures. The proposed reaction mechanism was established using these silver-doped materials. This work constitutes the first assessment to add low amounts of silver to increase the activity of this kind of catalytic materials for the CO oxidation reaction.

ZnO-Modified g-C3N4: A Potential Photocatalyst for Environmental Application.

Solar energy-driven practices using semiconducting materials is an ideal approach toward wastewater remediation. In order to attain a superior photocatalyst, a composite of g-C3N4 and ZnO (GCN–ZnO) has been prepared by one-step thermal polymerization of urea and zinc carbonate basic dihydrate [ZnNO3]2·[Zn(OH)2]3. The GCN–ZnO0.4 sample showed an evolved morphology, increased surface area (116 m2 g–1), better visible light absorption ability, and reduced band gap in comparison to GCN–pure. The GCN–ZnO0.4 sample also showed enhanced adsorption and photocatalytic activity performance, resulting in an increased reaction rate value up to 3 times that of GCN–pure, which was attributed to the phenomenon of better separation of photogenerated charge carriers resulting because of heterojunction development among interfaces of GCN–pure and ZnO. In addition, the GCN–ZnO0.4 sample showed a decent stability for four cyclic runs and established its potential use for abatement of organic wastewater pollutants in comparison to GCN–pure.

Time-dependent shapes of a dissolving mineral grain: Comparisons of simulations with microfluidic experiments

Experimental observations of the dissolution of calcium sulfate by flowing water have been used to investigate the assumptions underlying pore-scale models of reactive transport. Microfluidic experiments were designed to observe changes in size and shape as cylindrical disks (radius 10 mm) of gypsum dissolved for periods of up to 40 days. The dissolution flux over the whole surface of the sample can be determined by observing the motion of the interface. However, in order to extract surface reaction rates, numerical simulations are required to account for diffusional hindrance across the concentration boundary layer; the geometry is too complex for analytic solutions.We have found that a first-principles simulation of pore-scale flow and transport, with a single value of the surface reaction rate, was able to reproduce the time sequence of sample shapes without any fitting parameters. The value of the rate constant is close to recent experimental measurements but much smaller than some earlier values. The shape evolution is a more stringent test of the validity of the method than average measurements such as effluent concentration, because it requires the correct flux at each point on the sample surface.

Effect of microwave power intensity on synthesis of mesoporous titania nanoparticles for degradation of 2,4-dichlorophenol: Photoactivity performance and kinetic studies

In this study, mesoporous titania nanoparticles (MTN) were synthesized via microwave (MW)-assisted method under various heating power (0.12 (MTN1), 0.37 (MTN2) and 0.56 (MTN3) Wg−1). The performance of MTN was investigated on photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution using a batch reactor under visible light irradiation. The catalysts were characterized by XRD, UV-Vis DRS, BET and FTIR. The degradation of 2,4-DCP showed that catalyst synthesized at MTN2 was the most effective with 89.43% degradation compared to MTN1 and MTN3 with 82.93% and 86.99%, respectively. This result probably MTN2 has the lowest band gap and highest surface area compared to MTN1 and MTN3. The kinetic studies for degradation 2,4-DCP using MTN2 revealed that the reaction followed pseudo-first order kinetics with reaction rate values (kapp ) decreased as the initial concentration increased that proved the system was preferable at low concentration.

IRDFF-II: A New Neutron Metrology Library

High quality nuclear data is the most fundamental underpinning for all neutron metrology applications. This paper describes the release of version II of the International Reactor Dosimetry and Fusion File (IRDFF-II) that contains a consistent set of nuclear data for fission and fusion neutron metrology applications up to 60 MeV neutron energy. The library is intended to support: a) applications in research reactors; b) safety and regulatory applications in the nuclear power generation in commercial fission reactors; and c) material damage studies in support of the research and development of advanced fusion concepts. The paper describes the contents of the library, documents the thorough verification process used in its preparation, and provides an extensive set of validation data gathered from a wide range of neutron benchmark fields. The new IRDFF-II library includes 119 metrology reactions, four cover material reactions to support self-shielding corrections, five metrology metrics used by the dosimetry community, and cumulative fission products yields for seven fission products in three different neutron energy regions. In support of characterizing the measurement of the residual nuclei from the dosimetry reactions and the fission product decay modes, the present document lists the recommended decay data, particle emission energies and probabilities for 68 activation products. It also includes neutron spectral characterization data for 29 neutron benchmark fields for the validation of the library contents. Additional six reference fields were assessed (four from plutonium critical assemblies, two measured fields for thermal-neutron induced fission on 233U and 239Pu targets) but not used for validation due to systematic discrepancies in C/E reaction rate values or lack of reaction-rate experimental data. Another ten analytical functions are included that can be useful for calculating average cross sections, average energy, thermal spectrum average cross sections and resonance integrals. The IRDFF-II library and comprehensive documentation is available online at www-nds.iaea.org/IRDFF/. Evaluated cross sections can be compared with experimental data and other evaluations at www-nds.iaea.org/exfor/endf.htm. The new library is expected to become the international reference in neutron metrology for multiple applications.

The reaction rate and residual value of particle size fractions of limestone in southern New South Wales

Grain yield is frequently constrained by soil acidity in southern Australia yet limestone crushing plants are few and distant, making the use of limestone costly. The efficient technology of agricultural liming is therefore critical to the continuation of the practice following its adoption during the 1980s. We hypothesise that finer particles are the most effective materials for ameliorating soil acidity even over the longer term, when the residual value of coarser particles might be expected to be greater. Finer particle sizes of limestone, particularly <0.075 mm, initially gave the largest increases in soil pH per tonne of limestone applied. Despite the rapid and large increase in soil pH with finer particles, there was no less residual value in surface soil pH after 7 years or in grain yield in the 7th and 8th growing seasons compared with coarser particles. Most particle size fractions of limestone converged to a similar soil pHca at 0–10 cm depth after about 6 years but the coarsest particle size fraction (2–5 mm) lagged the other five. Finer particles also resulted in better movement of alkali and Ca into the subsurface soil layers below the depth of incorporation (0–10 cm). The measurement of unreacted limestone in the soil showed that the dissolution of limestone took up to 3 years (1807 mm of rainfall) for the 2.5 t/ha rate and up to 6 years (3592 mm) for the 5 t/ha rate. The rapid increase in soil pH in Year 1, the slow ongoing reaction of limestone over 3–6 years as measured by unreacted limestone, the slow but measurable improvement in subsurface acidity, and the sustained residual value to grain yield over in excess of eight seasons, indicate that the use of finer liming materials should remain a viable practice for growers.

Estudo da taxa de reação transfusional das instituições de saúde credenciadas à Rede Sentinela da Anvisa, do ano de 2017

Introduction: Haemosurveillance is an element for the safety of blood transfusion processes. The information provided by the Sentinel Network integrated the Post-National System of Sanitary Surveillance in registration and Post-Commercialization, with the purpose of subsidizing Sanitary Surveillance in the actions of regulation of these products. Objective: Obtain transfusion reaction rate (RT) values that reflect the situation of the institutions that make up the Sentinel Network, based on network monitoring data, in 2017. Method: A retrospective cross-sectional, descriptive study with a quantitative approach was performed. The study sample consisted of 172 spreadsheets from reports sent by 191 Sentinel Network member services, with data referring to the monitoring of at least one of the semesters of 2017. Results: Of the 254 accredited services in the Sentinel Network in 2017, 191 institutions submitted a report with data from at least one of the semesters during the study period. Of these services, 183 (95.8%) reported having had blood transfusions and 120 (62.8%) institutions sent spreadsheets with RT rates from the health facility. The overall rate of RT identified among institutions that make up the Sentinel Network for 2017 was 5.29 RT per 1,000 transfusions performed. Conclusions: The rate of RT identified was 5.29 RT per 1,000 transfusions. Identifying the transfusion reaction rate is an important step in institution’s risk management as it enables the development of quality improvement strategies in the transfusion process.

KEBERGANTUNGAN TEMPERATUR PLASMA HIDROGEN DALAM TEKANAN RENDAH

The density and reaction rate values of plasma are physical quantities needed to produce plasma hydrogen. Both are needed to estimate the heat and the operating time of plasma generator. Density and reaction rate of plasma values are obtained by computational modeling using the continuity and Arrhenius equation. Five spesies of hydrogen are used in this research i.e electron, H2, H2+, H and H+. The pressure used was 9.7 mTorr and the temperature of electron used is higher than the temperatures of the hydrogen species. The temperatures scale used in high at 34812 Kelvin for electron and 9283.2 for other species. The study resulted that hydrogen gas can be plasma when it reaches the time span 3.8x10-7second. The equilibrium conditions last for 10-3 second after the time limit be returned as plasma gas. The result of density for each species at range 1016 until 1018 m-3. The value of the fastest reaction rate equal to 7,3 x 1053 m-3 s-1.

The influence of palladium on the catalytic activity for ethanol conversion over heteropoly tungstate catalysts

The dehydration reaction was studied using pure and palladium doped Keggin type heteropoly compounds (H3PW12O40 and Cs2.5H0.5PW12O40) in the temperature range from 433 to 573 K. The structure and texture of catalysts were characterized by thermal analysis, FTIR, XRD, BET and SEM–EDS methods. Pd doped samples exhibit a deviation of Pd concentration value from the stoichiometric ones, while parent samples have concentration values similar to the stoichiometric ones. The catalytic activity of the compounds was tested by continuous flow reactor technique at different temperatures. The favorable effect of Pd doped on the catalysts for dehydration reaction to ethylene results from the examination of apparent activation energies Ea and reaction rate values. Evidence of a decreasing Ea was obtained for ethylene formation in the case of PdCs2.5PW (83.4 kJ/mol) comparatively with pure Cs2.5PW (160.7 kJ/mol). For all reaction temperatures, the reaction rates of ethylene formation are higher for palladium-doped samples than undoped ones.

Numerical Investigation on Porous Media Quenching Behaviors of Premixed Deflagrating Flame using RANS/LES Model

To understand the mechanism of premixed flame quenching by porous media, a zonal hybrid RANS/LES model was employed, in which the LES flow solver was used to resolve the large turbulent structures within the non-porous region, while RANS was applied to porous media zone. The predicted results were compared with previous experimental data. And it was evident that the premixed flame propagation rates and structure as well as quenching behaviors were reproduced by this numerical approach with a better accuracy. Due to the inherently higher heat transfer coefficients between the solid and gas phases in porous media, the gas phase temperature has been decreased rapidly. However, upstream obstacles can cause the flame propagating faster and thus reduce the axial gas temperature gradients, resulting in the invalidity of the operation of premixed flame quenching. By comparison with the case without upstream obstacle, the values of reaction rate attained in the case with three pairs of obstacles are higher, which makes a positive impact on the flame passing through the porous medium. In addition, the porous media with greater pore density has an excellent flame quenching property mainly owing to both the larger volumetric heat transfer and higher quenching temperature.

Oxy-steam reforming of methanol\xa0on copper catalysts

The influence of copper content in the monometallic catalysts supported on the CeO2·Al2O3 binary oxide system on their catalytic activity and physicochemical properties in oxy-steam reforming of methanol was investigated. It was shown that activity and selectivity depends on the content of copper, its dispersion on the catalysts surface. It was confirmed that optimal copper content was 20 wt% of Cu. Copper catalysts with 20 wt% of Cu exhibited the highest methanol conversion and reaction rate value compared to the rest of the investigated catalysts systems. The kinetic measurements performed in oxy-steam reforming of methanol on 20%Cu/CeO2·Al2O3 catalysts, showed an activation energy for this system equal Ea (OSRM) = 66.56 kJ/mol.

The modeling of the turbulent reaction rate under high-pressure conditions: A priori evaluation of the Conditional Source-term Estimation concept

With the goal of obtaining an accurate model of the turbulent reaction rate for Large Eddy Simulations (LESs), the modeling of turbulence-chemistry-thermodynamic interaction is addressed through an a priori study of a Direct Numerical Simulation (DNS) database representing high-pressure turbulent combustion. The DNS database consists of simulations of a temporal mixing layer in which a single-step chemical reaction occurs. The potential of the single-conditioned Conditional Source-term Estimation (CSE) approach to model the filtered turbulent reaction rate needed for conducting LES is examined. Evaluations conducted with the mixture fraction as a conditioning variable at two filter widths and with the probability density function (PDF) extracted from the DNS database that represents the mixture fraction, show that the deviation between the model and template is large and substantially increases with filter width. To address this deviation, the Double-conditioned CSE (DCSE) approach is explored with two different second conditioning variables, the first conditioning variable still being the mixture fraction; four filter widths are considered. The first choice of the second conditioning variable is a normalized progress variable based on the CO2 mass fraction and the second choice of the second conditioning variable is a normalized temperature. With each second conditional variable, the DCSE results represent a substantial improvement over CSE, by as much as an order of magnitude when measured by the relative error from the DNS-extracted filtered reaction rate. A quantitative test based on a root mean square identifies the reason for the DCSE success compared to CSE: unlike in CSE, the DCSE is able to substantially reduce the fluctuations of the modeled reaction rate from the filtered reaction rate over the entire range of the filtered reaction rate values, and particularly at the larger reaction rate values for which the DCSE model has higher fidelity. The results are shown to be equally favorable for the two conditioning variables. Consideration of DNS realizations at higher free-stream pressure or larger Reynolds number shows that the results are essentially equally successful at other pressure or Reynolds number values.

Effect of Co-precursor Maliec Anhydride on the Thermal Decomposition of Acetyl Ferrocene: A Reaction Kinetic Analysis

Background: Thermal decomposition of iron-bearing organometallic complex acetyl ferrocene, (C5H4COCH3)Fe(C5H5), leads to hematite (α-Fe2O3) nanoparticles. Presence of maliec anhydride, C4H2O3 as co-precursor during thermal decomposition modifies the size of the particles as well as the quantity of the reaction product significantly. Objective: Kinetic analysis of the solid-state thermal reaction of acetyl ferrocene in the presence of varying amount of co-precursor maliec anhydride under inert reaction atmosphere has been studied in order to understand the reaction mechanism involved behind the formation of hematite and the role of co-precursor in the reaction process. For this purpose, reaction kinetic analysis of three mixtures of acetyl ferrocene and maliec anhydride has been carried out. Methods: Thermogravimetry under non-isothermal protocol with multiple heating rates has been employed. The data are analyzed using model-free iso-conversional kinetic techniques to estimate the activation energy of reaction and reaction rate. The most-probable reaction mechanism has been identified by master plot method. The kinetic triplets (activation energy, reaction rate, most probable reaction mechanism function) have been employed to estimate the thermodynamic triplets (ΔS, ΔH and ΔG). Observations: Acetyl Ferrocene (AFc) undergoes thermal decomposition in a four-step process leaving certain residual mass whereas maliec anhydride (MA) undergoes complete mass loss owing to melting followed by evaporation. In contrast, the (AFc1-x-MAx) mixtures undergo thermal decomposition through a two-step process, and the decompositions are completed at much lower temperatures than that in AFc. The estimated activation energy and reaction rate values are found strongly dependent on the extent of conversion as well as on the extent of mixing. Introduction of MA in the solid reaction atmosphere of AFc in one hand reduces the activation energy required by AFc to undergo thermal decomposition and the reaction rate, while on the other hand varies the nature of reaction mechanism involved. Results: The range of reaction rate values estimated for the mixtures indicate that the activated complexes during Step-I of thermal decomposition may be treated as ‘loose’ complex whereas ‘tight’ complex for the Step-II. From the estimated entropy values, thermal process of (AFc1-x-MAx) mixture for Steps I and II may be interpreted as ‘‘slow’’ stage. Conclusion: Variation of Gibb’s free energy with the fraction of maliec anhydride in the mixtures for Step-I and II indicate that the thermal processes of changing the corresponding activated complexes are non-spontaneous at room temperature.

PENENTUAN DENSITAS PLASMA HIDROGEN NONTERMAL PADA TEKANAN RENDAH

Before producing hydrogen plasma low pressure in experiment, it is necessary to know the density equilibrium process through a simulation. Hydrogen species densities of non-thermal plasma at low pressure is simulated using chemical kinetik model by Runge Kutta method. This simulation carried out to determine the equilibrium process of densities and reaction rates of hydrogen species in achieving equilibrium conditions. The equation used time-dependent continuity equation and Arrhenius form. The hydrogen species consist of electrons, H, H2, H+ and H2+. The results of show that electron density, H, H2, H+ and H2+ are respectively 1020,23m-3, 1019,69m-3, 1019,91m-3, 1019,39m-3 and 1018,43m-3 during of 23-24 ns. These describe that the density of each species of hydrogen very fast to achieve equilibrium conditions, while the value of the reaction rate obtained can be concluded that the value of the largest reaction rate is the impact ionization process with a value of 9.86x1052m-3 s-1and the smallest one is dissociation process with a value of 1.22x10-5m-3 s-1.

Effects of Local Transverse Dispersion on Macro-scale Coefficients of Decaying Solute Transport in a Stratified Formation

Estimating the values of dispersion and biochemical reaction rates of heterogeneous aquifers is critical to predicting the temporal evolution and fate of reactive solutes. While previous studies have investigated field-scale heterogeneity of transport and biochemical properties of porous media, effects of local dispersion have not been well understood. In this paper, longitudinal macro-dispersivity, effective decay rate, and effective solute velocity are derived for a stratified aquifer, and the effects of local dispersion, especially the local transverse dispersion, are studied. It is shown that the inclusion of local transverse dispersion leads to enlarged effective decay rate, and that ignoring it may significantly underestimate the effective rate. The Damkohler (Da) number and the coefficient of variation (CV) of decay rate have slight influence to macro-coefficients under very small Pe number (with large local transverse dispersion). However, Da number has growing effect on the asymptotic effective decay rate with the decrease in Pe number, and results in constant asymptotic values regardless of Da number under the condition with very large Pe number. Larger CV of decay rate leads to smaller effective decay rate and effective velocity, and longitudinal macro-coefficient. The longitudinal macro-dispersivity is found to depend on the correlation between the hydraulic conductivity and the decay rate if the local longitudinal dispersion is spatially variable.

Sorption and desorption of BrF3 on NaF: Studies on thermodynamics and kinetics

Temperature dependence of bromine trifluoride vapor pressure over its adduct with sodium fluoride has been determined; the adduct normal dissociation temperature has been determined. Kinetics of sorption and desorption processes in BrF3(gas)–NaF(solid) system have been studied.The equation was proposed to illustrate the link between forward reaction rate (Ка) described by Arrhenius equation and experimental value (Ki):Ki= Kа⋅ (Pa/Peq)m,where Ki – observed reaction rate constant, Ka – forward reaction rate constant described by Arrhenius equation; Pa – partial pressure of BrF3; Peq – equilibrium pressure of BrF3 above BrF3⋅3NaF; m – factor characterizing the interaction area of BrF3 with NaF. The application of this equation makes possible to determine the true reaction rate values and reaction activation energy in chemisorption terms; it also helps to calculate the degree BrF3 sorption on NaF reaction at different temperatures and adsorbate pressures.The possibility of sorption-desorption separation of bromine trifluoride – uranium hexafluoride – iodine pentafluoride system with use of sodium fluoride was shown.