Hydrogenation of methylacetylene. IV. The reaction of methylacetylene with hydrogen catalyzed by palladium, platinum, iridium, rhodium, and ruthenium catalysts

1969 ◽  
Vol 47 (2) ◽  
pp. 215-221 ◽  
Author(s):  
R. S. Mann ◽  
K. C. Khulbe
Keyword(s):  
Activation Energies ◽  
Ruthenium Catalysts ◽  
Kcal Mole ◽  
Wide Range ◽  
Apparent Activation Energies ◽  
Palladium Platinum

The reaction between methylacetylene and hydrogen over pumice supported and unsupported palladium, platinum, iridium, rhodium, and ruthenium catalysts has been investigated between 12 and 160 °C for a wide range of reactant ratios. The order of reaction with respect to hydrogen was one and with respect to methylacetylene was zero to slightly negative. The overall apparent activation energies for supported and unsupported palladium, platinum, iridium, and rhodium were 10.5, 9.5, 12.4, 14.7, 8.6, 6.2, 10.7, and 11.7 kcal/mole respectively.

The Hydrogenation of Allene. IV. The Reaction of Allene with Hydrogen Catalyzed by Palladium, Platinum, Iridium, Rhodium, Ruthenium, and Osmium Catalysts

1972 ◽  
Vol 50 (12) ◽  
pp. 1793-1796 ◽  
Author(s):  
R. S. Mann ◽  
A. M. Shah
Keyword(s):  
Activation Energies ◽  
Constant Volume ◽  
Catalytic Activities ◽  
Wide Range ◽  
Apparent Activation Energies ◽  
Palladium Platinum

The reaction between allene and hydrogen over unsupported palladium, platinum, iridium, rhodium, ruthenium, and osmium catalysts has been investigated in a static constant volume system between 70 and 149 °C for a wide range of reactant ratios. The orders of reaction with respect to hydrogen and allene were one and zero, respectively, and temperature independent. The overall apparent activation energies for unsupported platinum, iridium, palladium and rhodium were 17.7, 9.1, 6.4, and 17.4 kcal/mol, respectively. The catalytic activities of the unsupported metals were in the sequence Pd > Ir > Rh > Pt > Ru, Os. Selectivity was highest with palladium and rhodium, and least with iridium. The polymerization was highest with platinum and least with indium.

scholarly journals Catalytic Hydrogenation of Methylacetylene

1967 ◽  
Vol 45 (10) ◽  
pp. 1023-1030 ◽  
Author(s):  
R. S. Mann ◽  
S. C. Naik
Keyword(s):  
Compensation Effect ◽  
Nickel Catalysts ◽  
Hydrogenation Reaction ◽  
Activation Energies ◽  
Reaction Vessel ◽  
Kcal Mole ◽  
Pressure Time ◽  
Wide Range ◽  
Exponential Factors ◽  
Apparent Activation Energies

The reaction between methylacetylene and hydrogen over supported and unsupported nickel catalysts has been investigated in a static constant volume system for a wide range of temperature and reactant ratios. The pressure–time curves consist of two linear portions of different slopes. The reaction over nickel is largely simple hydrogenation, the early stages being principally a selective production of propylene with small yields of reduced polymers of methylacetylene. The orders of the hydrogenation reaction are first and zero with respect to hydrogen and methylacetylene respectively. The overall apparent activation energies for nickel–pumice and nickel–kieselguhr are 16.8 and 14.0 kcal/mole and for unsupported nickel catalysts vary between 17.2 and 20.0 kcal/mole. A satisfactory "compensation effect" exists between the activation energies and logarithmic values of the pre-exponential factors. The unsupported catalysts were not poisoned when methylacetylene was added first to the reaction vessel.

The hydrogenation of allene. II. The reaction of allene with hydrogen catalyzed by nickel, cobalt, and iron

1968 ◽  
Vol 46 (20) ◽  
pp. 3249-3254 ◽  
Author(s):  
R. S. Mann ◽  
D. E. Tiu
Keyword(s):  
Activation Energies ◽  
Constant Volume ◽  
Cobalt Catalysts ◽  
Kcal Mole ◽  
Nickel Iron ◽  
Early Stages ◽  
Nickel Cobalt ◽  
Wide Range ◽  
Apparent Activation Energies ◽  
Selective Formation

The reaction between allene and hydrogen over unsupported nickel, iron, and cobalt catalysts has been studied in a static constant volume system for a wide range of temperature and reactant ratios. The reaction over metals is largely simple hydrogenation, the early stages being principally a selective formation of propylene with small yields of reduced polymers of allene. The orders of the hydrogenation were 1 and 0 with respect to hydrogen and allene respectively, and were temperature independent. The overall apparent activation energies for nickel, iron, and cobalt were 6.5, 7.6, and 6.9 kcal/mole respectively. Selectivity was highest with nickel, and least with cobalt.

scholarly journals Catalytic hydrogenation of allene

1968 ◽  
Vol 46 (2) ◽  
pp. 161-166 ◽  
Author(s):  
R. S. Mann ◽  
D. E. To
Keyword(s):  
Catalytic Hydrogenation ◽  
Hydrogenation Reaction ◽  
Activation Energies ◽  
Constant Volume ◽  
Kcal Mole ◽  
Catalytic Activities ◽  
Pressure Time ◽  
Wide Range ◽  
Apparent Activation Energies ◽  
Selective Formation

The reaction between allene and hydrogen over pumice-supported metals of the eighth group has been investigated in a constant volume reactor for a wide range of temperature and reactant ratios. The shape of the pressure–time curves were found to be dependent upon the reactant ratios and their order of admission. The reaction over nickel–pumice is principally a selective formation of propylene with small yields of propane and reduced polymers of allene. The orders of hydrogenation reaction are first, or slightly higher, and zero with respect to hydrogen and allene respectively. The apparent activation energies for Pd, Pt, Co, Fe, Ni, Rh, Ir, Ru, and Os are 13, 17.4, 10.8, 9.4, 7.8, 9.6, 5.3, 3.0, and 4.6 kcal/mole respectively. The catalytic activities of the metals are in the sequence[Formula: see text]While selectivity was found to decrease with increasing initial hydrogen pressures, it increased with increasing temperatures.

The hydrogenation of methylacetylene. II. The reaction of methylacetylene with hydrogen catalyzed by nickel, iron, and cobalt

1967 ◽  
Vol 45 (22) ◽  
pp. 2755-2760 ◽  
Author(s):  
R. S. Mann ◽  
K. C. Khulbe
Keyword(s):  
Cobalt Catalyst ◽  
Activation Energies ◽  
Constant Volume ◽  
Kcal Mole ◽  
Nickel Iron ◽  
Early Stages ◽  
Wide Range ◽  
Apparent Activation Energies

The reaction between methylacetylene and hydrogen over unsupported nickel, iron, and cobalt catalyst has been investigated in a static constant volume system for a wide range of temperature and reactant ratios. The reaction over metals is largely simple hydrogenation, the early stages being principally a selective production of propylene with small yields of reduced polymers of methylacetylene. The orders of the hydrogenation were first and zero to slightly negative with respect to hydrogen and methylacetylene. The overall apparent activation energies for nickel, iron, and cobalt were 12.2, 8.1, and 7.3 kcal/mole respectively. Selectivity was highest with iron and least with nickel.

scholarly journals Strahleninaktivierung von Ribonuclease bei erhöhten Temperaturen und unterschiedlichen Dosisraten

1968 ◽  
Vol 23 (7) ◽  
pp. 949-952 ◽  
Author(s):  
Klaus Kürzinger ◽  
Horst Jung
Keyword(s):  
Dose Rate ◽  
Cross Section ◽  
Room Temperature ◽  
Activation Energies ◽  
The Other ◽  
Radical Reactions ◽  
Kcal Mole ◽  
Apparent Activation Energies ◽  
Mev Protons ◽  
Dose Rate Effect

The radiosensitivity of dry ribonuclease was determined at various temperatures between 120 °K and 440 °K using 2 MeV protons. Within this temperature range the inactivation cross section S (T) of ribonuclease may be described as a function of temperature by the expression S(T) = (1.28 + 16·e-1000/RT+14000·e-6500/7RT)·10-14 cm2 .This result indicates that the observed radiation damage to ribonuclease is produced by three different mechanisms, one being independent of temperature, the other two having apparent activation energies of 1 kcal/mole and 6.5 kcal/mole, respectively. From these relatively small activation energies the conclusion may be drawn that radical reactions contribute to the inactivation of enzymes in the dry state. Experiments with Co gamma radiation showed that the radiosensitivity of ribonuclease at 77 °K depends on dose rate; at room temperature a dose rate effect was not observed.

Growth Rate Distributions during Recrystallization of Copper

2004 ◽  
Vol 467-470 ◽  
pp. 197-202 ◽  
Author(s):  
R.A. Vandermeer ◽  
Erik M. Lauridsen ◽  
Dorte Juul Jensen
Keyword(s):  
Pure Copper ◽  
Activation Energies ◽  
Individual Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Apparent Activation Energies ◽  
Diffraction Microscopy ◽  
Purity Copper

New 3D X-ray diffraction microscopy (3DXRD) experiments on recrystallizing bulk grains that nucleated and grew in a 92% cold deformed pure copper during in situ annealing at both 150° C and 160° C are described. Nucleation times, growth velocities and apparent activation energies were determined for each grain. A wide range of apparent activation energies was observed but the average of 123 kJ/mol agreed well with earlier recrystallization experiments on a similar purity copper. It was clear that each recrystallized grain had its own individual characteristics; the grains do not all behave alike as various models would suppose.

pH-Dependent Thermal Stability of Vibrio cholerae L-asparaginase

2019 ◽  
Vol 26 (10) ◽  
pp. 743-750 ◽  
Author(s):  
Remya Radha ◽  
Sathyanarayana N. Gummadi
Keyword(s):  
Vibrio Cholerae ◽  
Conformational Changes ◽  
Kinetic Studies ◽  
Structural Features ◽  
Structure Stability ◽  
Kcal Mole ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Ph Dependent ◽  
Ph Range

Background:pH is one of the decisive macromolecular properties of proteins that significantly affects enzyme structure, stability and reaction rate. Change in pH may protonate or deprotonate the side group of aminoacid residues in the protein, thereby resulting in changes in chemical and structural features. Hence studies on the kinetics of enzyme deactivation by pH are important for assessing the bio-functionality of industrial enzymes. L-asparaginase is one such important enzyme that has potent applications in cancer therapy and food industry.Objective:The objective of the study is to understand and analyze the influence of pH on deactivation and stability of Vibrio cholerae L-asparaginase.Methods:Kinetic studies were conducted to analyze the effect of pH on stability and deactivation of Vibrio cholerae L-asparaginase. Circular Dichroism (CD) and Differential Scanning Calorimetry (DSC) studies have been carried out to understand the pH-dependent conformational changes in the secondary structure of V. cholerae L-asparaginase.Results:The enzyme was found to be least stable at extreme acidic conditions (pH< 4.5) and exhibited a gradual increase in melting temperature from 40 to 81 °C within pH range of 4.0 to 7.0. Thermodynamic properties of protein were estimated and at pH 7.0 the protein exhibited ΔG37of 26.31 kcal mole-1, ΔH of 204.27 kcal mole-1 and ΔS of 574.06 cal mole-1 K-1.Conclusion:The stability and thermodynamic analysis revealed that V. cholerae L-asparaginase was highly stable over a wide range of pH, with the highest stability in the pH range of 5.0–7.0.

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