Thermodynamic Calculations on Vapour Phase Species in Halogen Doped CDTE

1994 ◽  
Vol 340 ◽  
Author(s):  
R. Schwarz ◽  
M. Laasch ◽  
K.W. Benz
Keyword(s):  
Gibbs Energy ◽  
Phase Boundary ◽  
Thermodynamic Analysis ◽  
Vapour Phase ◽  
Thermodynamic Calculations ◽  
Experimental Conditions ◽  
Energy Minimizer ◽  
Interface Kinetics

ABSTRACTA thermodynamic analysis of the vapour phase species occurring in the undoped CdTe and doped CdTe:X (X = Cl, Br, I) systems is given. Calculations are performed using a Gibbs energy minimizer software (EPC), which offers the possibility of receiving relativly prompt results allowing for the change in experimental conditions as well as the consideration of even spurious species.In each system, the dopant - transporting species are the cadmiumdihalogenides CdX2. Contrary, in the CdTe:I vapour phase two more species (Tel and I) have to be considered at the growing phase boundary afffecting transport and interface kinetics.

scholarly journals Transformation of 2-Butene into Propene on WO3/MCM-48: Metathesis and Isomerization of n-Butene

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 585 ◽  
Author(s):  
Derun Hua ◽  
Zheng Zhou ◽  
Qianqian Hua ◽  
Jian Li ◽  
Xinning Lu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
High Temperatures ◽  
Thermodynamic Analysis ◽  
Reaction Temperature ◽  
Thermodynamic Calculations ◽  
Metathesis Reaction ◽  
Good Catalytic Activity

The metathesis of 2-butene (Trans and Cis) to propene was investigated over W-based catalysts. Thermodynamic calculations for metathesis and isomerization were carried out at various temperatures to test the reactions. The results showed that the WO3/MCM-48 catalyst had good catalytic activity. The metathesis activity depended on the acidity of the catalyst and the dispersity of the WO3 on the supports. High temperatures promoted the isomerization of 2-butene to 1-butene. According to thermodynamic analysis, however, this is adverse to the metathesis reaction, making it important to determine an appropriate reaction temperature.

The measurement and prediction of sustained temperature oscillations in a chemical reactor

1969 ◽  
Vol 309 (1496) ◽  
pp. 1-26 ◽  
Keyword(s):  
Mathematical Analysis ◽  
Methyl Chloride ◽  
Chemical Reactor ◽  
Vapour Phase ◽  
Gas Temperature ◽  
Experimental Conditions ◽  
Temperature Oscillations ◽  
Series Of Experiments ◽  
Steady Oscillations

Steady oscillations in the recorded gas temperature have been observed in a series of experiments in which the vapour-phase chlorination of methyl chloride was carried out. The instability was reproducible and persisted within a sharply defined range of reaction temperatures. A mathematical analysis of the dynamics of the reacting system is found to predict closely the nature and frequency of the oscillations and the range of experimental conditions within which they occur.

Continuous and simultaneous measurement of triple oxygen and hydrogen isotopes of liquid and vapour during evaporation

2020 ◽  
Author(s):  
Matthew Brady ◽  
David Hodell
Keyword(s):  
High Precision ◽  
Standard Error ◽  
Numerical Models ◽  
Hydrogen Isotopes ◽  
Vapour Phase ◽  
Integration Time ◽  
Experimental Conditions ◽  
Liquid Injection ◽  
Oxygen And Hydrogen Isotopes ◽  
The Mean

<p>Here, we describe a system for measuring triple oxygen and hydrogen isotopic ratios of both the liquid and vapour during evaporation of water in a dry gas stream (N2 or dry air) at constant temperature and relative humidity (RH).  The hardware consists of a polymer glove box (COY), peristaltic pump (Ismatec), and Picarro L2140-i cavity ring-down laser spectrometer (CRDS) with Standard Delivery Module (SDM). Liquid water from the evaporation pan is sampled via a closed recirculating loop and syringe pump that delivers a constant rate of water to the vaporizer, maintaining a constant concentration of water vapour in the cell (20,000 ±103, 1 s.d.) over an injection cycle. Liquid measurements alternate with vapour from the glove box which is introduced to the CRDS using a diaphragm gas pump. Important for high-precision measurements, both cavity pressure and outlet valve stability are maintained throughout the liquid injection and subsequent vapour phase. Experiments are bookended by two in-house standards which are calibrated to the SMOW-SLAP scales. An additional drift corrector is introduced periodically.</p><p> </p><p>To test the precision and stability of the liquid injections, we sampled from an isotopically homogeneous volume of water and introduced it to the cavity over a period of ~48h. To minimise the standard deviation derived from noise, we chose an optimum integration time of ~2000s (~33 minutes) based on σ<sub>Allan </sub>minimisation. Therefore, for combined liquid-vapour experiments we use an injection/vapour sampling window of 40-minutes (140ug water is consumed per injection), which provides a data collection period of 33-minutes after a 7-min waiting time for equilibration.</p><p> </p><p>Across a single liquid injection, the mean standard error for d<sup>17</sup>O, d<sup>18</sup>O, and dD is 0.008‰, 0.007‰, and 0.02‰, respectively. For the vapour phase equivalent, the mean standard error for d<sup>17</sup>O, d<sup>18</sup>O, and dD is 0.01‰, 0.009‰, 0.03‰ respectively. For the d-excess in the liquid and the vapour across one 33-minute cycle, the standard error is 0.07‰ and 0.08‰, respectively. For the O17-excess in the liquid and the vapour across one 33-minute cycle, the standard error is 6 per meg and 8 per meg, respectively.</p><p> </p><p>A single evaporation experiment produces in excess of 100,000 measurements each of d<sup>17</sup>O, d<sup>18</sup>O, and dD for both the evaporating liquid and resulting vapour. These measurements result in 95% confidence limits for the slope of ln(d<sup>17</sup>O+1) vs ln(d<sup>18</sup>O+1) of ±0.0002 and ±0.0003 for the liquid and vapour, respectively.  For the slope of ln(dD+1) vs ln(d<sup>18</sup>O+1) we obtain a 95% confidence interval of ±0.001 and ±0.002 for the liquid and vapour, respectively. The experimental method permits measurement of fractionation of triple oxygen and hydrogen isotopes of water under varying experimental conditions (e.g., RH, temperature, turbulence) at very high precision. It will be useful for testing numerical models of evaporation and conducting experiments to simulate evaporation and isotopic equilibration in natural systems. An application to closed-basin lakes will be presented.</p>

Thermodynamic Analysis of the Reduction of WO3 by Al Powder

2012 ◽  
Vol 581-582 ◽  
pp. 616-619
Author(s):  
Lian Ping Chen ◽  
Yuan Hong Gao ◽  
Bai Tao Su
Keyword(s):  
Gibbs Energy ◽  
Ball Milling ◽  
Thermodynamic Analysis ◽  
Room Temperature ◽  
Tungsten Powder ◽  
Tungsten Oxides ◽  
Al Powder

Hydrogen is widely used to prepare tungsten from tungsten oxides. Such a gas is combustible and strict measures must be taken. However, assisted by Mg or Li3N, tungsten can be prepared through the ball milling at room temperature. The reduction of WO3by Al powder is investigated thermodynamically. Simulations on the loss of Gibbs energy of these hypothetic reactions reveal that the reduction of WO3and WO2(OH)2(or H2WO4) is feasible when Al powder is used; and it is more difficult to generate the intermediate tungsten oxides such as WO2, WO2.72and WO2.9. In addition, it is better to prepare tungsten powder in vacuum containers in view of economy.

scholarly journals The effect of 'impure' pore fluids on metamorphic dissociation reactions

1962 ◽  
Vol 33 (256) ◽  
pp. 9-25 ◽  
Author(s):  
Peter J. Wyllie
Keyword(s):  
Open System ◽  
Vapour Phase ◽  
Pore Fluid ◽  
Phase Changes ◽  
Fluid Composition ◽  
Experimental Conditions ◽  
Phase Rule ◽  
Upper Limit ◽  
Dissociation Temperature ◽  
Mineralogical Phase

Summary Comparison of experimental data from the systems MgO-CO2-H2O (closed) and MgO-CO2-A (simulating an open system) shows that the effects of H2O and A on the dissociation of magnesite are almost identical; both behave as inert components reducing the partial pressure of CO2. The dissociation temperature at constant total pressure is lowered according to the proportion of inert volatiles in the initial vapour phase. The dissociation is completed at one temperature (univariant) in an open system but in a closed system it proceeds through a temperature interval (divariant) because the vapour phase changes composition. The amount of dissociation remains small until the upper limit of the interval is reached. More complex dissociation reactions in the systems CaO-MgO-CO2-H2O and CaO-SiO2-CO2-H2O are described; they follow similar patterns. Under closed or partially open metamorphic conditions non-reacting pore fluid components (inert) have to be treated as one additional component for application of the mineralogical phase rule. Comparison of the pattern of metamorphic parageneses with the patterns of reactions occurring under known experimental conditions may provide information about metamorphic processes. Metamorphic reactions can be represented within a petrogenetic model with axes P, T, and pore fluid composition varying between H2O and CO2.

scholarly journals Calculation of the thermodynamic properties of the Ga-Sb-Tl liquid alloys

2005 ◽  
Vol 70 (1) ◽  
pp. 9-20 ◽  
Author(s):  
Dragan Manasijevic ◽  
Dragana Zivkovic ◽  
Katayama Iwao ◽  
Zivan Zivkovic
Keyword(s):  
Thermodynamic Properties ◽  
Gibbs Energy ◽  
Ternary System ◽  
Thermodynamic Model ◽  
Excess Gibbs Energy ◽  
Similarity Coefficient ◽  
Thermodynamic Calculations ◽  
Liquid Alloys ◽  
Geometric Models ◽  
Good Agreement

The results of the calculation of the thermodynamic properties for liquid Ga-Sb-Tl alloys at the temperature 1073 K are presented in this paper. Initially, the most appropriate thermodynamic model for the investigated system was selected. Based on a comparison of the values calculated by different geometric models (Kohler, Muggianu, Toop, Hillert, Chou) with the existing experimental based data, asymmetric models of calculation were determined to give the best results. The asymmetric nature of the investigated ternary system was additionally confirmed by the Chou similarity coefficient concept. For these reasons, further complete thermodynamic calculations were performed according to the Hillert model in five sections of the ternary Ga-Sb-Tl system from each corner with the mole ratio of other two components being 9:1; 7:3; 5:5; 3:7 and 1:9. The obtained results include integral excess Gibbs energy dependences on composition for all the investigated sections. The calculated activity values at 1073 K for all components are given in the form of isoactivity diagrams. Comparison between the calculated and experimentally obtained gallium activities shows good agreement.

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