Isomerization of butene over a chromia–alumina catalyst

1969 ◽  
Vol 47 (2) ◽  
pp. 323-329 ◽  
Author(s):  
H. C. Chen ◽  
R. R. Hudgins ◽  
P. L. Silveston
Keyword(s):  
Partial Pressure ◽  
Total Pressure ◽  
Active Sites ◽  
Catalyst Deactivation ◽  
Surface Reactions ◽  
Alumina Catalyst ◽  
Isomerization Rate ◽  
Partial Pressures ◽  
Cis And Trans ◽  
Micro Reactor

Isomerization runs were performed in a micro-reactor at 325 °C over a range of butene partial pressure of 84 to 763 mm Hg and at a total pressure of approximately 1 atm. The isomerization rate of 1-butene passed through a maximum with increasing 1-butene partial pressure; the isomerization rate of cis- and trans-2-butene increased asymptotically with increasing cis- and trans-2-butene partial pressures respectively. Stereoselectivity was observed in the isomerization of each butene, and was found to be independent of pressure. Catalyst deactivation resulted in loss in stereoselectivity. Results suggest that surface reactions control isomerization and proceed simultaneously on different active sites.

OPTICAL AND ELECTRICAL PROPERTIES OF VANADIUM NITRIDE THIN FILMS

1999 ◽  
Vol 13 (07) ◽  
pp. 833-839 ◽  
Author(s):  
M. GHANASHYAM KRISHNA ◽  
A. K. BHATTACHARYA
Keyword(s):  
Thin Films ◽  
Partial Pressure ◽  
Total Pressure ◽  
Optical Constants ◽  
Vanadium Nitride ◽  
Nitrogen Partial Pressure ◽  
Dc Magnetron Sputtering ◽  
Partial Pressures ◽  
Similar Dependence ◽  
Quartz Substrates

Vanadium nitride thin films have been deposited on to quartz substrates by dc magnetron sputtering at two different total pressures and a series of nitrogen partial pressures. The spectral transmittance of these films, in the region 350 to 1500 nm, is strongly dependent on the nitrogen partial pressure during sputtering and relatively insensitive to total pressure. The films became more transparent as the nitrogen partial pressure was decreased at a constant total pressure. The optical constants, refractive index and extinction coefficient, exhibited a similar dependence on the nitrogen partial pressure. The sheet resistivity of the films decreased with increasing nitrogen partial pressure. The values of resistivity indicate that the films are semiconducting rather than metalic.

The Influence of Total and Oxygen Partial Pressures on Structure and Hydrophilic Property of TiO2 Thin Films Deposited by Reactive DC Magnetron Sputtering

2008 ◽  
Vol 55-57 ◽  
pp. 465-468 ◽  
Author(s):  
Surasing Chaiyakun ◽  
A. Buranawong ◽  
T. Deelert ◽  
N. Witit-Anun
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Total Pressure ◽  
Dc Magnetron Sputtering ◽  
Tio2 Thin Films ◽  
Rutile Structure ◽  
Hydrophilic Property ◽  
Partial Pressures

TiO2 thin films have been deposited by reactive DC magnetron sputtering technique to study the effect of total pressure and oxygen partial pressure on structure and hydrophilic properties. The crystal structure and hydrophilic property was measured by XRD and contact angle meter, respectively. The results showed that the films were composed of pure rutile and mixed of anatase/rutile structure dependent on the total pressure and oxygen partial pressure. It was found that all films can perform hydrophilic property. In case of high total pressure, the films showed superhydrophilic property, whereas the films deposited under various oxygen partial pressures with fixed total pressure were all films exhibit superhydrophilic property.

Characterization of Ruo2 Films Prepared by Rf Reactive Magnetron Sputtering

1998 ◽  
Vol 541 ◽  
Author(s):  
Li-jian Meng ◽  
M.P. dos Santos
Keyword(s):  
Magnetron Sputtering ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Total Pressure ◽  
High Stress ◽  
Reactive Magnetron Sputtering ◽  
Reactive Magnetron ◽  
Low Oxygen ◽  
X Ray Diffraction ◽  
Partial Pressures

AbstractRuthenium dioxide films have been prepared by rf reactive magnetron sputtering at different oxygen partial pressures and total sputtering pressures. The films have been characterized by scanning electron microscopy, X-ray diffraction and electrical conductivity. The films prepared at low oxygen partial pressure and total pressure show a strong preferred orientation along the [110] direction. As both pressures increased, the peak intensity decreases. All the films are subject to a compressive stress. As the total pressure is decreased and the oxygen partial pressure is increased, the stress increases. When the total pressure is lower than 6 × 10−3 mbar and the oxygen partial pressure is higher than 1 × 103 mbar, the films peeled off automatically from the substrate because of the high stress. The films prepared at high oxygen partial pressure and high total pressure have a rough surface and those prepared at low pressure show smooth surface. In this paper, these phenomena have been discussed. In addition, the electrical properties of the films are also discussed.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

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.

Sulfidation Experiments in a Pressurized Thermogravimetric Analyzer With Chinese Calcined Limestones

2005 ◽  
Author(s):  
Zhanlong Song ◽  
Mingyao Zhang
Keyword(s):  
Partial Pressure ◽  
Reaction Temperature ◽  
Total Pressure ◽  
Volume Fraction ◽  
Nitrogen Adsorption ◽  
Reaction Rates ◽  
Thermogravimetric Analyzer ◽  
Morphological Studies ◽  
Shrinking Core ◽  
Structure Properties

The sulfidation experiments with two kinds of Chinese calcined limestones were performed in a pressurized thermogravimetric analyzer (PTGA). The effects of reaction temperature (700–950°C), total pressure (0–1MPa), particle size (0.055–2mm), and H2S concentration (0.1–4%) on the sorbent conversions were analyzed. Morphological studies with scanning electron microscope and energy dispersive spectroscopy (SEM-EDS) equipment were made to obtain the pictures of solid surface and of the cross-sectioned samples. Nitrogen adsorption measurements were applied to determine the pore structure properties of the particles. Experimental results show that the sulfidation rate increases with total pressure when the volume fraction of H2S is constant. However, the rate of sulfidation decreases with the increase of total pressure when the H2S partial pressure is constant. Reaction temperature affects the sulfidation greatly, and the reaction rate increases with temperature. The sulfidation is the first order with respect to H2S partial pressure. Moreover, larger particles result in lower conversions and reaction rates. The unreacted shrinking core model was applied to describe the sulfidation to determine the kinetic parameters.

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.

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