56 research outputs found
Highly sensitive coulometric titration of oxygen for the characterization of solid materials at elevated temperatures
A new setup for characterization of solid material oxygen exchange and
conductivity in a broad oxygen partial pressure range and at elevated
temperatures is presented. The development target of this setup is directed
towards the detection of ultra-low amounts of exchanged oxygen. For this,
electrochemical cells made of yttria-stabilized zirconia (YSZ) were optimized
and applied in a flow-through arrangement. The design and process measures
enable a lower limit of detection below 100 pmol of exchanged oxygen.
Furthermore, the system characteristics concerning oxygen dispersion,
titration efficiency and electrode kinetics are described.</p
ΠΠΠΠ―ΠΠΠ ΠΠΠ’ΠΠΠ ΠΠΠΠ£Π§ΠΠΠΠ― ΠΠ ΠΠΠ‘ΠΠ ΠΠ¦ΠΠΠΠΠ«Π Π‘ΠΠΠΠ‘Π’ΠΠ ΠΠΠΠΠ‘Π’Π Π£ΠΠ’Π£Π ΠΠ ΠΠΠΠΠΠΠΠ ΠΠΠ ΠΠ¨ΠΠ MgO
Magnesium oxide is widely used as an adsorbent, catalyst, identifier of chemical and toxic pollutants, in water and gas purification processes. Mesoporous magnesium oxide powder has been synthesized by the method of deposition, spray pyrolysis and glycine-citrate-nitrate method, their crystal structure, microstructure, granulometric composition and adsorption properties have been studied. Optimal conditions for the production of magnesium oxide by the glycine-citrate-nitrate method have been determined, which make it possible to obtain a powder with average primary particle sizes of 12 nm and the smallest sizes of secondary particles starting from 70 nm. The influence of the method of obtaining nanostructured magnesium oxide powder on the physicochemical properties is established. High values of the total pore volume of 1.038 cm3 /g exhibited the MgO powder obtained by the precipitation method.ΠΠΊΡΠΈΠ΄ ΠΌΠ°Π³Π½ΠΈΡ Π½Π°Ρ
ΠΎΠ΄ΠΈΡ ΡΠΈΡΠΎΠΊΠΎΠ΅ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ Π°Π΄ΡΠΎΡΠ±Π΅Π½ΡΠ°, ΠΊΠ°ΡΠ°Π»ΠΈΠ·Π°ΡΠΎΡΠ°, ΠΈΠ΄Π΅Π½ΡΠΈΡΠΈΠΊΠ°ΡΠΎΡΠ° Π·Π°Π³ΡΡΠ·Π½ΡΡΡΠΈΡ
Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈ ΡΠΎΠΊΡΠΈΡΠ΅ΡΠΊΠΈΡ
Π²Π΅ΡΠ΅ΡΡΠ², Π² ΠΏΡΠΎΡΠ΅ΡΡΠ°Ρ
Π²ΠΎΠ΄ΠΎ- ΠΈ Π³Π°Π·ΠΎΠΎΡΠΈΡΡΠΊΠΈ. Π Π½Π°ΡΡΠΎΡΡΠ΅ΠΉ ΡΠ°Π±ΠΎΡΠ΅ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΠΎΡΠ°ΠΆΠ΄Π΅Π½ΠΈΡ, ΡΠ°ΡΠΏΡΠ»ΠΈΡΠ΅Π»ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΈΡΠΎΠ»ΠΈΠ·Π° ΠΈ Π³Π»ΠΈΡΠΈΠ½-ΡΠΈΡΡΠ°Ρ-Π½ΠΈΡΡΠ°ΡΠ½ΡΠΌ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΡΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½Ρ ΠΌΠ΅Π·ΠΎΠΏΠΎΡΠΈΡΡΡΠ΅ ΠΏΠΎΡΠΎΡΠΊΠΈ ΠΎΠΊΡΠΈΠ΄Π° ΠΌΠ°Π³Π½ΠΈΡ, ΠΈΠ·ΡΡΠ΅Π½Π° ΠΈΡ
ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΡΠ΅ΡΠΊΠ°Ρ ΡΡΡΡΠΊΡΡΡΠ°, ΠΌΠΈΠΊΡΠΎΡΡΡΡΠΊΡΡΡΠ°, Π³ΡΠ°Π½ΡΠ»ΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΠΉ ΡΠΎΡΡΠ°Π² ΠΈ Π°Π΄ΡΠΎΡΠ±ΡΠΈΠΎΠ½Π½ΡΠ΅ ΡΠ²ΠΎΠΉΡΡΠ²Π°. ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Ρ Π½Π°ΠΈΠ±ΠΎΠ»Π΅Π΅ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΡΠ΅ ΡΡΠ»ΠΎΠ²ΠΈΡ ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΡ ΠΎΠΊΡΠΈΠ΄Π° ΠΌΠ°Π³Π½ΠΈΡ Π³Π»ΠΈΡΠΈΠ½-ΡΠΈΡΡΠ°Ρ-Π½ΠΈΡΡΠ°ΡΠ½ΡΠΌ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ, ΠΊΠΎΡΠΎΡΡΠ΅ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡ ΠΏΠΎΠ»ΡΡΠΈΡΡ ΠΏΠΎΡΠΎΡΠΎΠΊ ΡΠΎ ΡΡΠ΅Π΄Π½ΠΈΠΌΠΈ ΡΠ°Π·ΠΌΠ΅ΡΠ°ΠΌΠΈ ΠΏΠ΅ΡΠ²ΠΈΡΠ½ΡΡ
ΡΠ°ΡΡΠΈΡ 12 Π½ΠΌ ΠΈ Π½Π°ΠΈΠΌΠ΅Π½ΡΡΠΈΠΌΠΈ ΡΠ°Π·ΠΌΠ΅ΡΠ°ΠΌΠΈ Π²ΡΠΎΡΠΈΡΠ½ΡΡ
ΡΠ°ΡΡΠΈΡ β ΠΎΡ 70 Π½ΠΌ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ Π²Π»ΠΈΡΠ½ΠΈΠ΅ ΡΠΏΠΎΡΠΎΠ±Π° ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΡ Π½Π° Π°Π΄ΡΠΎΡΠ±ΡΠΈΠΎΠ½Π½ΡΠ΅ ΡΠ²ΠΎΠΉΡΡΠ²Π° Π½Π°Π½ΠΎΡΡΡΡΠΊΡΡΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΡΠΊΠ° ΠΎΠΊΡΠΈΠ΄Π° ΠΌΠ°Π³Π½ΠΈΡ. ΠΡΡΠΎΠΊΠΈΠ΅ Π·Π½Π°ΡΠ΅Π½ΠΈΡ ΠΎΠ±ΡΠ΅Π³ΠΎ ΠΎΠ±ΡΠ΅ΠΌΠ° ΠΏΠΎΡ 1,038 ΡΠΌ3 /Π³ ΠΏΡΠΎΠ΄Π΅ΠΌΠΎΠ½ΡΡΡΠΈΡΠΎΠ²Π°Π» ΠΏΠΎΡΠΎΡΠΎΠΊ MgO, ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΠΉ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΠΎΡΠ°ΠΆΠ΄Π΅Π½ΠΈΡ
Π‘ΠΠΠ’ΠΠ Π ΠΠΠ‘ΠΠ ΠΠ¦ΠΠΠΠΠ«Π Π‘ΠΠΠΠ‘Π’ΠΠ ΠΠΠΠΠ‘Π’Π Π£ΠΠ’Π£Π ΠΠ ΠΠΠΠΠΠ«Π₯ ΠΠΠ ΠΠ¨ΠΠΠ Mg(OH)2 Π MgO
Magnesium oxide has found applications as adsorbent, catalyst and ideutifier of the contamination of chemicals and toxic substances in the processes of water and gases purification. In this work, mesoporous magnesium hydroxide and oxide were synthesized from water solutions by easy and cheap wet chemistry method. Crystal structure, particle size distribution and adsorption properties of the synthesized powders were studied. Obtained powders of Mg(OH)2 and MgO showed sufficiently high total pore volume β 0.737 and 1.038 cm3 /g, respectively, which opens an opportunity to use them as nanoreactors for the synthesis of isolated nanosized particles and multidirection catalysts.Β ΠΠΊΡΠΈΠ΄ ΠΌΠ°Π³Π½ΠΈΡ Π½Π°Ρ
ΠΎΠ΄ΠΈΡ ΡΠΈΡΠΎΠΊΠΎΠ΅ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ Π°Π΄ΡΠΎΡΠ±Π΅Π½ΡΠ°, ΠΊΠ°ΡΠ°Π»ΠΈΠ·Π°ΡΠΎΡΠ°, ΠΈΠ΄Π΅Π½ΡΠΈΡΠΈΠΊΠ°ΡΠΎΡΠ° Π·Π°Π³ΡΡΠ·Π½ΡΡΡΠΈΡ
Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈ ΡΠΎΠΊΡΠΈΡΠ΅ΡΠΊΠΈΡ
Π²Π΅ΡΠ΅ΡΡΠ², Π² ΠΏΡΠΎΡΠ΅ΡΡΠ°Ρ
Π²ΠΎΠ΄ΠΎ- ΠΈ Π³Π°Π·ΠΎΠΎΡΠΈΡΡΠΊΠΈ. Π Π½Π°ΡΡΠΎΡΡΠ΅ΠΉ ΡΠ°Π±ΠΎΡΠ΅ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΠΎΡΠ°ΠΆΠ΄Π΅Π½ΠΈΡ ΡΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½Ρ ΠΌΠ΅Π·ΠΎΠΏΠΎΡΠΈΡΡΡΠ΅ ΠΏΠΎΡΠΎΡΠΊΠΈ Π³ΠΈΠ΄ΡΠΎΠΊΡΠΈΠ΄Π° ΠΈ ΠΎΠΊΡΠΈΠ΄Π° ΠΌΠ°Π³Π½ΠΈΡ, ΠΈΠ·ΡΡΠ΅Π½Π° ΠΈΡ
ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΡΠ΅ΡΠΊΠ°Ρ ΡΡΡΡΠΊΡΡΡΠ°, ΠΌΠΈΠΊΡΠΎΡΡΡΡΠΊΡΡΡΠ°, Π³ΡΠ°Π½ΡΠ»ΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΠΉ ΡΠΎΡΡΠ°Π² ΠΈ Π°Π΄ΡΠΎΡΠ±ΡΠΈΠΎΠ½Π½ΡΠ΅ ΡΠ²ΠΎΠΉΡΡΠ²Π°. ΠΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΠΏΠΎΡΠΎΡΠΊΠΈ Mg(OH)2 ΠΈ MgO ΠΏΡΠΎΠ΄Π΅ΠΌΠΎΠ½ΡΡΡΠΈΡΠΎΠ²Π°Π»ΠΈ Π²ΡΡΠΎΠΊΠΈΠ΅ Π·Π½Π°ΡΠ΅Π½ΠΈΡ ΠΎΠ±ΡΠ΅Π³ΠΎ ΠΎΠ±ΡΠ΅ΠΌΠ° ΠΏΠΎΡ β 0,737 ΠΈ 1,038 ΡΠΌ3 /Π³ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΠΎ, ΡΡΠΎ ΠΎΡΠΊΡΡΠ²Π°Π΅Ρ ΡΠΈΡΠΎΠΊΠΈΠ΅ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΠΈ ΠΈΡ
ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ Π½Π°Π½ΠΎΡΠ΅Π°ΠΊΡΠΎΡΠΎΠ² Π΄Π»Ρ ΡΠΈΠ½ΡΠ΅Π·Π° Π½Π°Π½ΠΎΡΠ°Π·ΠΌΠ΅ΡΠ½ΡΡ
ΠΈΠ·ΠΎΠ»ΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΡΠ°ΡΡΠΈΡ ΠΈ ΡΠΎΠ·Π΄Π°Π½ΠΈΡ Π½Π° ΠΈΡ
ΠΎΡΠ½ΠΎΠ²Π΅ ΠΏΠΎΠ»ΠΈΠΌΠ°ΡΡΡΡΡΠ½ΡΡ
ΠΊΠ°ΡΠ°Π»ΠΈΠ·Π°ΡΠΎΡΠΎΠ².
Correlation between thermodynamic and thermomechanical quantities of selected perovskite-type oxides
Solid state synthesis, structure and transport properties of compositions in the system
DoubleBperovskite-type CaRu1βxTixO3βΔ±series withx=0,0.1,0.2...0.9, 1.0 were synthesized in air by solidstate reactions from simple ruthenium and titanium oxides and CaCO3. Crystal structures of CaRu1βxTixO3samples have been refined in space groupPnma(GdFeO3-type of structure) assuming statistical distri-bution of Ru and Ti species over the octahedral sites. Electrical conductivity and thermal expansion wereinvestigated att= 20β1000β¦C andpO2= 1β21000 Pa. Apart from CaRuO3with a combined p-/n-type con-ductivity depending on temperature andpO2, all other compositions are n-type semiconductors. Theconductivity of CaRuO3decreases with increasing temperature (metal-type). The Ti-containing compo-sitions withx= 0.1β0.2 change their conductivity dependence from metal-type at relatively low oxygenpartial pressures (pO2) to semi-conducting-type at relatively high ones. The materials withx> 0.2 havethe semi-conducting-type dependence at all investigatedpO2. Disproportionation of Ru4+into Ru3+andRu5+cations is considered for explanation of the conductivity dependences on temperature andpO2.The investigated compositions show high catalytic activity for propene oxidation and no activity for NO2reduction
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