scholarly journals Vapour phase catalytic transformations of terpene hydrocarbons in the C10H16 series. IV. Effect of nitrogen, hydrogen, and pyridine on the dehydrogenation of Δ3-carene over chromia and chromia-alumina catalysts

1977 ◽  
Vol 55 (16) ◽  
pp. 3046-3049 ◽  
Author(s):  
V. Krishnasamy ◽  
L. M. Yeddanapalli
Keyword(s):  
Partial Pressure ◽  
Vapour Phase ◽  
Catalytic Transformations ◽  
Partial Pressures ◽  
Alumina Catalysts ◽  
Catalyst Surfaces

The influences of nitrogen, hydrogen, and pyridine on the conversion of 3-carene into various products over chromia catalyst at 450 °C and over chromia–alumina at 400 °C have been investigated. Nitrogen acts as a diluent over these catalysts; hydrogen at low partial pressures enhances the formation of cymenes over chromia, but suppresses its formation over chromia–alumina. Increase of the partial pressure of hydrogen increases the proportion of men thanes over chromia–alumina, but decreases it over chromia catalyst. Pyridine suppresses the over-all conversion of 3-carene and the formation of cymenes over chromia and chromia–alumina; however, it increases the formation of menthadienes over chromia–alumina. These observations are explained in terms of the acidity of chromia and chromia–alumina, the diluting effects of nitrogen, hydrogen, and pyridine, and their ability to adsorb and desorb over the catalyst surfaces.

Vapour phase catalytic transformations of terpene hydrocarbons in the C10H16 series. III. Dehydrogenation of Δ3-carene over modified chromia and chromia–alumina catalysts

1976 ◽  
Vol 54 (21) ◽  
pp. 3458-3463 ◽  
Author(s):  
V. Krishnasamy ◽  
L. M. Yeddanapalli
Keyword(s):  
Hydrofluoric Acid ◽  
Vapour Phase ◽  
Potassium Ions ◽  
Total Conversion ◽  
Fluoride Ions ◽  
Catalytic Transformations ◽  
Alumina Catalysts

The vapour phase dehydrogenation of 3-carene has been studied over chromia, chromia–alumina, chromia doped with potassium, and chromia–alumina doped with potassium and fluoride ions. Addition of potassium to chromia and chromia–alumina up to 1% by weight does not significantly affect the overall conversion of 3-carene whereas it increases its dehydrogenation to p- and m-cymenes. Potassium ions above 1% lower both the total conversion and dehydrogenation of 3-carene to cymenes. The ratio of p- to m-cymene over chromia–alumina is enhanced by added potassium ions up to 2%, but over chromia it remains unaffected. Addition of potassium to chromia decreases the formation of menthanes and menthadienes but its addition to chromia–alumina reduces the formation of menthanes and increases that of menthadienes. Impregnation of chromia–alumina with hydrofluoric acid suppresses the formation of menthadienes and increases that of menthanes. All these are explained in terms of the effect of added potassium and fluoride ions on the acidity of the catalysts.

Effect of CO2 on Anti-Corrosion Property of a Polyurea Coating Modified with Organosilicone

2014 ◽  
Vol 789 ◽  
pp. 466-470
Author(s):  
Qing Hao Shi ◽  
Bing Ying Wang ◽  
Bin Zhao
Keyword(s):  
High Temperature ◽  
Partial Pressure ◽  
Composite Coating ◽  
Corrosion Test ◽  
Electrochemical Impedance ◽  
Failure Process ◽  
Corrosion Property ◽  
Corrosion Mechanism ◽  
Partial Pressures ◽  
High Temperature High Pressure

The corrosion mechanism of organic silicon modified polyurea composite coating under different CO2 partial pressures was studied using high-temperature autoclave, combined with scanning electron microscopy (SEM), adhesion tests and electrochemical impedance spectroscopy (EIS) technology. The experimental results showed that: there was no corrosion product formed on the surface of coating sample after high-temperature high-pressure corrosion test, and with the increasing of CO2 partial pressure, the coating adhesion and impedance values decline increases. Moreover CO2 partial pressure increases accelerated the failure process of polyurea composite coating system.

Recrystallization of Oxygen Contaminated Al Films

1986 ◽  
Vol 71 ◽  
Author(s):  
G.J. Van Der Kolk ◽  
M.J. Verkerk
Keyword(s):  
Grain Size ◽  
Silicon Nitride ◽  
Substrate Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Relative Increase ◽  
Partial Pressures ◽  
Average Grain Size

AbstractAl was evaporated at oxygen partial pressures, PO2, varying between 10−7 and 10−4 Pa on substrates of silicon nitride. The substrate temperature was varied between 20 °C and 250°C. The films were annealed at temperatures up to 500°C.For Al films deposited at 20°C, it was found that the average grain size decreases with increasing oxygen partial pressure. After annealing recrystallization was observed. The relative increase of grain size was less for higher values of pO2. Annealing gave rise to a broad grain size distribution.For Al films deposited at 250°C, the presence of oxygen caused the growth of rough inhomogeneous films. This inhomogeneous structure remained during annealing.

Controlled partial melting during isobaric and isothermal processing of dipcoated Bi-2212/Ag tapes

1998 ◽  
Vol 13 (12) ◽  
pp. 3580-3586 ◽  
Author(s):  
A. L. Crossley ◽  
J. L. MacManus-Driscoll
Keyword(s):  
Phase Diagram ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Partial Melting ◽  
Coulometric Titration ◽  
Processing Route ◽  
Optimum Processing ◽  
Partial Pressures ◽  
Titration Technique

A detailed study has been made of the control and optimization of partial melting of dipcoated Bi2Sr2Ca1Cu2O8+δAg0.1 (Bi-2212) tapes using reduced oxygen partial pressures. A coulometric titration technique has been employed to vary the oxygen partial pressure in a region of the phase diagram corresponding to binary melting, and the amount of partial melting has been quantified. Using this information, tapes have been processed using both isothermal and isobaric techniques. An optimum processing route was determined which combined isothermal and isobaric processes. Highly aligned material at the point of optimum melting was obtained.

Effects of acetone in heparin on the multiple inert gas elimination technique

1985 ◽  
Vol 58 (4) ◽  
pp. 1143-1147 ◽  
Author(s):  
F. L. Powell ◽  
F. A. Lopez ◽  
P. D. Wagner
Keyword(s):  
Partial Pressure ◽  
Dead Space ◽  
Room Temperature ◽  
Inert Gas ◽  
Published Data ◽  
Physiological Mechanisms ◽  
Heparinized Saline ◽  
Partial Pressures ◽  
Ventilation Perfusion Ratio ◽  
Mixed Venous

We have detected acetone in several brands of heparin. If uncorrected, this leads to errors in measuring acetone in blood collected in heparinized syringes, as in the multiple inert gas elimination technique for measuring ventilation-perfusion ratio (VA/Q) distributions. Error for acetone retention [R = arterial partial pressure-to-mixed venous partial pressure (P-V) ratio] is usually small, because R is normally near 1.0, and the error is similar in arterial and mixed venous samples. However, acetone excretion [E = mixed expired partial pressure (P-E)-to-P-V ratio] will appear erroneously low, because P-E is accurately measured in dry syringes, but P-V is overestimated. A physical model of a homogeneous alveolar lung at room temperature and without dead space shows: the magnitude of acetone E error depends upon the ratio of blood sample to heparinized saline volumes and acetone partial pressures, without correction, acetone E can be less than that of less soluble gases like ether, a situation incompatible with conventional gas exchange theory, and acetone R and E can be correctly calculated using the principle of mass balance if the acetone partial pressure in heparinized saline is known. Published data from multiple inert gas elimination experiments with acetone-free heparin, in our labs and others, are within the limits of experimental error. Thus the hypothesis that acetone E is anomalously low because of physiological mechanisms involving dead space tissue capacitance for acetone remains to be tested.

scholarly journals Structural, optical and electrical properties of reactively sputtered CrxNy films: Nitrogen influence on the phase formation

2017 ◽  
Vol 11 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Mirjana Novakovic ◽  
Maja Popovic ◽  
Zlatko Rakocevic ◽  
Natasa Bibic
Keyword(s):  
Partial Pressure ◽  
Phase Formation ◽  
Rutherford Backscattering Spectrometry ◽  
Deposition Process ◽  
Columnar Structure ◽  
Nitrogen Partial Pressure ◽  
Tem Analysis ◽  
Dense Microstructure ◽  
Transmission Electron ◽  
Partial Pressures

The properties of various CrxNy films grown by direct current (DC) reactive sputtering process with different values of nitrogen partial pressures (0, 2?10-4, 3.5?10-4 and 5?10-4 mbar) were studied. The structural analysis of the samples was performed by using X-ray diffraction and transmission electron microscopy (TEM), while an elemental analysis was realized by means of Rutherford backscattering spectrometry. By varying nitrogen partial pressure the pure Cr layer, mixture of Cr, Cr2N and CrN phases, or single-phase CrN was produced. TEM analysis showed that at pN2 = 2?10-4 mbar the layer has dense microstructure. On the other hand, the layer deposited at the highest nitrogen partial pressure exhibits pronounced columnar structure. The optical properties of CrxNy films were evaluated from spectroscopic ellipsometry data by the Drude or combined Drude and Tauc-Lorentz model. It was found that both refractive index and extinction coefficient are strongly dependent on the dominant phase formation (Cr, Cr2N, CrN) during the deposition process. Finally, the electrical studies indicated the metallic character of Cr2N phase and semiconducting behaviour of CrN.

Tensile Properties and Creep Behavior of SiC-Based Fibers under Various Oxygen Partial Pressures

2005 ◽  
Vol 475-479 ◽  
pp. 1333-1336 ◽  
Author(s):  
Jan Ji Sha ◽  
J.S. Park ◽  
Tatsuya Hinoki ◽  
Akira Kohyama ◽  
J. Yu
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Tensile Properties ◽  
Creep Behavior ◽  
Elevated Temperatures ◽  
Low Oxygen ◽  
X Ray Diffraction ◽  
Sic Fibers ◽  
Partial Pressures ◽  
Ar Gas

Three kinds of atmospheres (air, highly-pure Ar and ultra highly-pure Ar gas) with different oxygen partial pressures were applied to investigate the tensile properties and creep behavior of SiC fibers such as Hi-NicalonTM and TyrannoTM-SA. These fibers were annealed and crept at elevated temperatures ranging from1273-1773 K in such environments. After annealing at 1773 K, the room temperature tensile strengths of SiC-based fibers decreased with decreasing the oxygen partial pressure and the near stoichiometric fiber TyrannoTM-SA shows excellent strength retention. At temperatures above the 1573 K, the creep resistance of SiC fibers evaluated by bending stress relaxation (BSR) method under high oxygen partial pressure was lower than that of in low oxygen partial pressure. The microstructural features on these fibers were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

Über die Instabilität von NiTiO3 unter der Wirkung eines Sauerstoffpartialdruck-Gradienten Instability of NiTiO3 in an Oxygen-Potential Gradient

1981 ◽  
Vol 36 (10) ◽  
pp. 1211-1214 ◽  
Author(s):  
W. Laqua
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Potential ◽  
Potential Gradient ◽  
Simultaneous Action ◽  
Partial Pressures ◽  
Quantitative Explanation

Abstract If a NiTiO3 poly crystal is exposed to an oxygen-potential gradient -established by the simultaneous action of two different oxygen partial pressures -it will be decomposed into its component oxides NiO and TiO2 despite the fact, that the compound is stable at both the lower and the higher oxygen partial pressure. A quantitative explanation of this phenomenon will be given below.

Inhibition of CO2 Assimilation by Supraoptimal CO2: Effect of Light and Temperature

1983 ◽  
Vol 10 (1) ◽  
pp. 75 ◽  
Author(s):  
KC Woo ◽  
SC Wong
Keyword(s):  
Partial Pressure ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Quantum Yields ◽  
Co2 Partial Pressure ◽  
Low Co2 ◽  
O2 Partial Pressure ◽  
Partial Pressures ◽  
High Partial Pressure ◽  
Partial Pressure Of Co2

In cotton the rate of CO2 assimilation, at O2 partial pressures up to 200 mbar, increased to a maximum and then declined as the intercellular partial pressure of CO2 was increased. The specific intercellular partial pressure of CO2 at which rate of assimilation began to decline depended on the environmental conditions. At 19 mbar partial pressure of O2 the decline occurred at CO2 partial pressure >390 �bar. At 200 mbar partial pressure of O2 it occurred at CO2 partial pressure > 534 �bar. O2 increased the CO2 partial pressure required for inhibition but it did not appear to affect the steepness of the decline of rate of assimilation with further increase in partial pressure of CO2 once the decline became apparent. The decline was more readily observed at low temperature and low O2 partial pressure, and in plants grown at low light and NO3- levels. It was also observed in cowpea and sunflower. Changes in quantum efficiency in cotton at high and low CO2 concentrations were observed. At ambient CO2 concentration (300 �bar), the quantum yields measured at 19 and 200 mbar partial pressure of O2 were 0.072 � 0.0003 and 0.053 � 0.0060 mol CO2 per mol absorbed quanta, respectively. In contrast, at 900 �bar CO2 partial pressure the respective values were 0.050 � 0.0023 and 0.070 � 0.0006 mol CO2 per mol absorbed quanta. The nature of the inhibition of CO2 assimilation by high partial pressure of CO2 is discussed.

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