ChemInform Abstract: Effect of the Partial Pressures of Oxygen and Water Vapour on the Dispersity of α-Cr2O3, Obtained by Thermal Decomposition of Hydrated Chromium(III) Oxide.

1983 ◽  
Vol 14 (31) ◽  
Author(s):  
D. G. KLISSURSKI ◽  
V. N. BLUSKOV
Keyword(s):  
Thermal Decomposition ◽  
Water Vapour ◽  
Partial Pressures

Effect of the partial pressures of oxygen and water vapour on the dispersity of α-Cr2O3 obtained by thermal decomposition of hydrated chromium(III) oxide

1983 ◽  
Vol 61 (3) ◽  
pp. 457-460 ◽  
Author(s):  
Dimitar G. Klissurski ◽  
Vladimir N. Bluskov
Keyword(s):  
Thermal Decomposition ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Specific Surface ◽  
Water Vapour ◽  
Sharp Increase ◽  
Decomposition Product ◽  
Argon Atmosphere ◽  
Partial Pressures ◽  
Highly Dispersed

The effect of water vapour and oxygen partial pressure on the thermal decomposition of hydrated chromium (III) oxide has been studied. A decrease in the water vapour partial pressure from 20 to 1 × 10−3 mm Hg has been found to produce a sharp increase in the specific surface area of the decomposition product (α-Cr2O3). Decomposition in an argon atmosphere leads to highly dispersed α-Cr2O3 even at relatively high temperatures (400–500 °C).

Analogues of the active and inactive sodium carbonate

1982 ◽  
Vol 47 (12) ◽  
pp. 3348-3361 ◽  
Author(s):  
Erich Lippert ◽  
Karel Mocek ◽  
Emerich Erdös
Keyword(s):  
Thermal Decomposition ◽  
Time Dependence ◽  
Water Vapour ◽  
Sulphur Dioxide ◽  
Atmospheric Pressure ◽  
Flow Reactor ◽  
Kinetic Measurements ◽  
Sodium Potassium ◽  
Alkaline Metals ◽  
Hydrogen Carbonates

The reactivity of the anhydrous carbonates of alkaline metals with sulphur dioxide has been studied experimentally in dependence both on the nature of the cation and on the way of preparation of the anhydrous carbonate. The carbonates were prepared either by thermal decomposition of hydrogen carbonates or by thermal dehydration of carbonate hydrates. The carbonates of lithium, sodium, potassium, rubidium and caesium have been investigated. Kinetic measurements were carried out in a flow reactor in the integral regime at 423 K under atmospheric pressure, with a gas containing 0.2 vol.% of sulphur dioxide and 2.0 vol.% of water vapour in the nitrogen as a carrier gas. The reactivities have been compared on the basis of time dependence of the conversion of carbonate to sulphite.

Synthesis and study of diaboleïte

1968 ◽  
Vol 36 (283) ◽  
pp. 933-939 ◽  
Author(s):  
R. E. Winchell ◽  
H. E. Wenden
Keyword(s):  
Water Vapour ◽  
Atmospheric Pressure ◽  
Stable Phase ◽  
Line Position ◽  
Natural Mineral ◽  
X Ray ◽  
Partial Pressures ◽  
Cell Dimensions ◽  
Natural And Synthetic

SummaryDiaboleïte has been synthesized between 25 and 100° C at atmospheric pressure and approximate water vapour partial pressures of 14·7 lb/in2. Under similar conditions at 170° C cumengéite appears to be the stable phase produced from a diaboleïte composition. Synthetic diaboleïte is much simpler morphologically than the natural mineral but the hemimorphic symmetry is more clearly demonstrated morphologically in the artificial specimens. A comparison of X-ray powder data for natural and synthetic diaboleïte shows almost exact detailed correspondence in line position and intensity between 0 and 180° 2θ. The cell dimensions obtained from X-ray powder data are a 5·869 ± 0·002 Å and c 5·495 ± 0·003 Å.

Kinetics of the Reaction of Solid Anhydrous Potassium Carbonate with Gaseous Sulfur Dioxide

1994 ◽  
Vol 59 (11) ◽  
pp. 2357-2374 ◽  
Author(s):  
Erich Lippert ◽  
Karel Mocek ◽  
Emerich Erdös
Keyword(s):  
Sulfur Dioxide ◽  
Water Vapour ◽  
Potassium Carbonate ◽  
Anhydrous Potassium Carbonate ◽  
Heterogeneous Reaction ◽  
Fixed Bed ◽  
Partial Pressures ◽  
Flow Apparatus ◽  
Gaseous Sulfur ◽  
Kinetics Of

Results are presented of an experimental kinetic study of the heterogeneous reaction between gaseous sulfur dioxide and solid anhydrous potassium carbonate. The measurements were carried out in an all glass kinetic flow apparatus with nitrogen as the carrier gas and a fixed bed of the solid working in the differential regime at atmospheric pressure and a temperature of 423 K (150 °C). The reaction course was studied in dependence on the partial pressures of sulfur dioxide (pSO2) and water vapour (pH2O) in concentration ranges pSO2 = 13 - 430 Pa and pH2O = 0 - 2 100 Pa. In the reaction, water vapour acts as a gaseous catalyst. Based on the experimental data, the corresponding kinetic equation was found together with the numerical values of the relevant rate and equilibrium adsorption constants.

Thermal decomposition of hydromagnesite 4MgCO3 - Mg(OH)2 - 4H2O under different partial pressures of carbon dioxide

1978 ◽  
Vol 27 (1-3) ◽  
pp. 45-59 ◽  
Author(s):  
Yutaka Sawada ◽  
Keizo Uematsu ◽  
Nobuyasu Mizutani ◽  
Masanori Kato
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
Partial Pressures

scholarly journals Phase coexistence and critical temperatures of the (Bi, Pb)2Sr2Ca2Cu3Ox phase under partial pressures of oxygen between 10−3 and 0.21 bar with and without additions of silver

1997 ◽  
Vol 12 (6) ◽  
pp. 1445-1450 ◽  
Author(s):  
M. Däumling ◽  
R. Maad ◽  
A. Jeremie ◽  
R. Flükiger
Keyword(s):  
Thermal Decomposition ◽  
Stability Region ◽  
Decomposition Temperature ◽  
Superconducting Phase ◽  
Phase Coexistence ◽  
Critical Temperatures ◽  
X Ray ◽  
Narrow Region ◽  
Partial Pressures ◽  
The Stability

We have investigated the stability of the (Bi, Pb)2Sr2Ca2Cu3Ox phase for the stoichiometry (Bi: Pb: Sr:Ca: Cu = 1.72: 0.34: 1.83: 1.97: 3.13), subjecting it to temperatures between 700 and 850 °C under various oxygen partial pressures. A narrow region was found in which Bi, Pb(2223) was the only superconducting phase. This region follows closely the thermal decomposition line. X-ray pure Bi, Pb(2223) will partially decompose if treated outside of the stability region. For a given oxygen partial pressure, the Bi, Pb(2223) phase tends to coexist with the 2201 phase for temperatures above, and the 2212 phase for temperatures below this region. At even lower temperatures an additional lead-rich phase appears. Critical temperatures Tc vary little with treatment and range between 108.5 K and 110.8 K. If 10% silver is added to the starting powder, the phase coexistence regions shift. Silver does not seem to have a significant effect on the absolute values of the critical temperature. The Bi, Pb(2223) thermal decomposition temperature for a given oxygen pressure is lowered by at least 10 K by the presence of Ag.

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