Hydrogenation of methylacetylene. III. The reaction of methylacetylene with hydrogen catalyzed by nickel, copper, and their alloys

1968 ◽  
Vol 46 (4) ◽  
pp. 623-633 ◽  
Author(s):  
R. S. Mann ◽  
K. C. Khulbe
Keyword(s):  
Activation Energy ◽  
Nickel Catalyst ◽  
Hydrogen Pressure ◽  
Constant Volume ◽  
Temperature Dependent ◽  
Nickel Copper ◽  
Wide Range ◽  
Initial Hydrogen Pressure

The reaction between methylacetylene and hydrogen over unsupported nickel, copper, and their alloys has been investigated in a static constant volume system between 20 and 220 °C for a wide range of reactant ratios. The order of reaction with respect to hydrogen was one and nearly independent of temperature. While the order of reaction with respect to methylacetylene over nickel catalyst was slightly negative and temperature dependent, it was always positive and nearly independent of temperature for copper and copper-rich alloys. Selectivity was independent of initial hydrogen pressure for nickel and copper only; for others it decreased rapidly with increasing hydrogen pressure. The overall activation energy varied between 9 and 21.2 kcal/g mole. Selectivity and extent of polymerization increased with increasing amount of copper in the alloy.

The reaction of 2-butyne with hydrogen catalyzed by nickel, copper, cobalt, iron, and nickel–copper alloys

1970 ◽  
Vol 48 (13) ◽  
pp. 2075-2089 ◽  
Author(s):  
R. S. Mann ◽  
C. P. Khulbe
Keyword(s):  
Copper Alloy ◽  
Hydrogen Pressure ◽  
Copper Alloys ◽  
Kcal Mole ◽  
Temperature Dependent ◽  
Nickel Cobalt ◽  
Nickel Copper ◽  
Wide Range ◽  
Cobalt Iron ◽  
Initial Hydrogen Pressure

The reaction between hydrogen and 2-butyne over unsupported nickel, copper, cobalt, iron, and nickel–copper alloys has been investigated in a static constant volume system between 30 and 250 °C for a wide range of reactant ratios. The reaction over metals and their alloys is simple hydrogenation, the early stages being principally a selective production of cis-2-butene with small yields of polymers. The order of reaction with respect to hydrogen was one and independent of temperature. While the order of reaction over cobalt and copper with respect to 2-butyne was zero, it was slightly negative and temperature dependent for nickel and nickel–copper alloys. The selectivity was independent of initial hydrogen pressure for nickel, cobalt, copper and most of the nickel–copper alloys. The overall activation energy for nickel, cobalt, and copper were 9.1, 6.6, 33.5 kcal/mole, respectively. Selectivity and extent of polymerization increased with increasing amounts of copper in the nickel–copper alloy.

Simulation of the Temperature Dependence of Hall Carriers in Al Doped 4H-SiC

2012 ◽  
Vol 717-720 ◽  
pp. 237-240 ◽  
Author(s):  
Anindya Nath ◽  
Raffaele Scaburri ◽  
Mulpuri V. Rao ◽  
Roberta Nipoti
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Electrical Properties ◽  
Energy Level ◽  
Weighted Least Squares ◽  
High Dose ◽  
Global Minima ◽  
Temperature Dependent ◽  
Wide Range ◽  
Scattering Factor

A global minima search weighted and non-weighted least squares algorithm has been employed for a comparative study of various possible models to describe electrical properties of high dose Al implanted 4H-SiC. A wide range of experimental data has been taken from literature to demonstrate validation of the model. It was found that a single activation energy level, a temperature dependent Hall scattering factor and a degeneracy factor equal to 4 lead to a satisfactory fitting of experimental Hall data up to an Al substitutional density of 1020cm 3 in 4H SiC.

Hydrogen Diffusion in Quartz: A Molecular Dynamics Investigation

1995 ◽  
Vol 408 ◽  
Author(s):  
A. Bongiorno ◽  
L. Colombo
Keyword(s):  
Activation Energy ◽  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Diffusion Path ◽  
Arrhenius Law ◽  
Hydrogen Diffusivity ◽  
Temperature Dependent ◽  
Crystalline Quartz ◽  
Wide Range

AbstractWe present a molecular dynamics investigation on hydrogen diffusivity in crystalline quartz by computing the diffusion coefficient over a wide range of temperatures (700K < T < 1500K) and by characterizing the diffusion path and mechanism. Our main findings are: (i) hydrogen diffusion is anisotropically confined along the c-axis in α- and β-quartz; (ii) hydrogen diffuses through a jump-like mechanism; (iii) the temperature-dependent diffusivity follows an Arrhenius law with activation energy of 0.56 eV and 0.27 eV for α-and β-quartz, respectively.

Catalyst Selection for Hydrogenation of 1,2-Dihydroacenaphthylene

1998 ◽  
Vol 63 (11) ◽  
pp. 1945-1953 ◽  
Author(s):  
Jiří Hanika ◽  
Karel Sporka ◽  
Petr Macoun ◽  
Vladimír Kysilka
Keyword(s):  
Activation Energy ◽  
Nickel Catalyst ◽  
Palladium Catalyst ◽  
Active Component ◽  
Reaction Order ◽  
Nickel Catalysts ◽  
Practical Application ◽  
Repeated Use ◽  
Selection For ◽  
Catalyst Selection

The activity of ruthenium, palladium, and nickel catalysts for the hydrogenation of 1,2-dihydroacenaphthylene in cyclohexane solution was studied at temperatures up to 180 °C and pressures up to 8 MPa. The GC-MS technique was used to identify most of the perhydroacenaphthylene stereoisomers, whose fractions in the product were found dependent on the nature of the active component of the catalyst. The hydrogenation was fastest on the palladium catalyst (3% Pd/C). The nickel catalyst Ni-NiO/Al2O3, which is sufficiently active also after repeated use, can be recommended for practical application. The activation energy of 1,2-dihydroacenaphthylene hydrogenation using this catalyst is 17 kJ/mol, the reaction order with respect to hydrogen is unity.

scholarly journals Study and Assessment of Defect and Trap Effects on the Current Capabilities of a 4H-SiC-Based Power MOSFET

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 735
Author(s):  
Fortunato Pezzimenti ◽  
Hichem Bencherif ◽  
Giuseppe De Martino ◽  
Lakhdar Dehimi ◽  
Riccardo Carotenuto ◽  
...  
Keyword(s):  
Drain Current ◽  
Oxide Semiconductor ◽  
Temperature Dependent ◽  
Channel Mobility ◽  
Blocking Voltage ◽  
Current Voltage ◽  
Wide Range ◽  
Temperature Ranges ◽  
Joint Contribution ◽  
State Resistance

A numerical simulation study accounting for trap and defect effects on the current-voltage characteristics of a 4H-SiC-based power metal-oxide-semiconductor field effect transistor (MOSFET) is performed in a wide range of temperatures and bias conditions. In particular, the most penalizing native defects in the starting substrate (i.e., EH6/7 and Z1/2) as well as the fixed oxide trap concentration and the density of states (DoS) at the 4H-SiC/SiO2 interface are carefully taken into account. The temperature-dependent physics of the interface traps are considered in detail. Scattering phenomena related to the joint contribution of defects and traps shift the MOSFET threshold voltage, reduce the channel mobility, and penalize the device current capabilities. However, while the MOSFET on-state resistance (RON) tends to increase with scattering centers, the sensitivity of the drain current to the temperature decreases especially when the device is operating at a high gate voltage (VGS). Assuming the temperature ranges from 300 K to 573 K, RON is about 2.5 MΩ·µm2 for VGS > 16 V with a percentage variation ΔRON lower than 20%. The device is rated to perform a blocking voltage of 650 V.

Nickel-Catalyzed Electronically-Reversed Enantioselective Hydrocarbofunctionalizations of Acrylamides

Synlett ◽  
2021 ◽  
Author(s):  
Lou Shi ◽  
Wei Shu
Keyword(s):  
Nickel Catalyst ◽  
Functional Group ◽  
Optically Active ◽  
Forming Process ◽  
Carbon Bond ◽  
Bond Forming ◽  
Synthetic Strategy ◽  
Carbon Carbon Bond ◽  
Wide Range ◽  
Simple Protocol

Asymmetric hydrocarbofunctionalizations of alkenes has emerged as an efficient synthetic strategy for accessing optically active molecules via carbon-carbon bond-forming process from readily available alkenes and carbo-electrophiles. Herein, we present a summary of the efforts from our group to control the regio- and enantioselectivity of hydrocarbofunctionalizations of electron-deficient alkenes with a nickel catalyst and chiral bisoxazolidine ligand. The reaction undergoes electron-reversed hydrocarbofunctionalizations acrylamides with excellent enantioselectivity. This operationally simple protocol enables the asymmetric hydroalkylation, hydrobenzylation and hydropropargylation of acrylamides. This reaction is useful for preparing a wide range of α-branched chiral amides with broad functional group tolerance.

Temperature-dependent activation energy and variable range hopping in semi-insulating GaAs

2006 ◽  
Vol 21 (12) ◽  
pp. 1681-1685 ◽  
Author(s):  
R M Rubinger ◽  
G M Ribeiro ◽  
A G de Oliveira ◽  
H A Albuquerque ◽  
R L da Silva ◽  
...  
Keyword(s):  
Activation Energy ◽  
Variable Range Hopping ◽  
Temperature Dependent ◽  
Variable Range

The hydrogenation of allene. III. The reaction of allene with hydrogen catalyzed by nickel, copper, and their alloys

1970 ◽  
Vol 48 (21) ◽  
pp. 3324-3331 ◽  
Author(s):  
R. S. Mann ◽  
A. M. Shah
Keyword(s):  
Copper Content ◽  
Activation Energies ◽  
Constant Volume ◽  
Early Stages ◽  
Nickel Copper ◽  
Selective Formation

The reaction between allene and hydrogen over unsupported nickel, copper, and their alloys has been investigated in a static constant volume system between 26 and 131 °C for a wide reactant ratios. The orders of reaction with respect to hydrogen and allene were one and zero, respectively, and temperature independent. The reaction over metals and their alloys is largely simple hydrogenation, the early stages being principally a selective formation of propylene, with small yields of reduced polymers of allene. The overall activation energies varied between 4.8 and 11.8 kcal/g-mole. Selectivity was highest with copper and least with nickel. The amount of allene polymerized was not related in any particular way to the copper content of alloy.

Magnetic properties of undoped and Co-doped n-type β–FeSi2.5 single crystals

2002 ◽  
Vol 17 (11) ◽  
pp. 2960-2965 ◽  
Author(s):  
E. Arushanov ◽  
L. Ivanenko ◽  
D. Eckert ◽  
G. Behr ◽  
U. K. Rößler ◽  
...  
Keyword(s):  
Activation Energy ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
External Field ◽  
Single Crystals ◽  
Spin Glasses ◽  
Paramagnetic Centers ◽  
Temperature Dependent ◽  
Paramagnetic Curie Temperature ◽  
Co Doped

Results of magnetization and magnetic susceptibility measurements on undoped and Co-doped FeSi2.5 single crystals are presented. The temperature dependence of the magnetic susceptibility of the Co-doped sample in the range of 5–300 K can be explained by temperature-dependent contributions due to paramagnetic centers and the carriers excited thermally in the extrinsic conductivity region. The values of the paramagnetic Curie temperature and activation energy of the donor levels were estimated. It is also shown that the magnetic susceptibility of Co-doped samples cooled in zero external field and in a field are different. This resembles the properties of spin-glasses and indicates the presence of coupling between magnetic centers.

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