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.

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.

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. 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.

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.

Nitric oxide and oxygen reactions with 1-butene over manganese(III) oxide

1983 ◽  
Vol 61 (12) ◽  
pp. 2767-2772 ◽  
Author(s):  
Robert Anderson Ross ◽  
Craig Fairbridge
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Reaction Rates ◽  
Activation Energies ◽  
Complete Combustion ◽  
Differential Flow ◽  
Exponential Factors ◽  
Unburned Hydrocarbons ◽  
Apparent Activation Energies ◽  
Nitrate Species

Reactions of 1-butene with nitric oxide from 623 to 723 K and with oxygen from 433 to 573 K have been studied in a differential flow system over manganese(III) oxide. Nitrous oxide was formed in the reaction of the hydrocarbon with nitric oxide along with products of complete combustion. The apparent activation energies were respectively 69 ± 4, 78 ± 4, and 30 ± 4 kJ mol−1 for nitrogen, carbon dioxide, and nitrous oxide reaction rates. The corresponding pre-exponential factors were 1.72 × 10−1 and 1.16 mol0.5 L−0.5 m2 g−1, and 1.99 × 10−2 mol−0.35 L0.35 m2 g−1. In the reaction with oxygen, apparent activation energies of 183 ± 4, 523 to 503 K, and 88 ± 4 kJ mol−1, 503 to 433 K, were determined with pre-exponential factors 1.74 × 1015 and 2.94 × 105 mol0.3 m−2 g−1. During catalysis the oxide underwent a partial phase change from α to γ in both reactions. Additionally, nitrate species were present on the surface after oxidation with nitric oxide. Kinetic expressions have been derived and mechanisms proposed for both reactions which may occur in emission control systems requiring the removal of NOx and unburned hydrocarbons.

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.

REACTIONS OF THE ETHYL RADICAL: IV. ADDITION TO VINYL MONOMERS

1965 ◽  
Vol 43 (3) ◽  
pp. 633-639 ◽  
Author(s):  
D. G. L. James ◽  
Duncan MacCallum
Keyword(s):  
Gas Phase ◽  
Vinyl Monomers ◽  
Kcal Mole ◽  
Ethyl Radical ◽  
Wide Range ◽  
Exponential Factors ◽  
Representative Selection ◽  
Intrinsic Reactivity ◽  
Radical Attack ◽  
Selection Of

The Arrhenius parameters have been measured for the addition of the ethyl radical to a representative selection of vinyl monomers in the gas phase. The wide range of reactivity observed was almost entirely due to the variation of the energy of activation, from 3.4 ± 0.4 kcal/mole for acrylonitrile to 6.9 ± 0.5 kcal/mole for vinyl acetate. No significant variation was found among the values of the pre-exponential factors, indicating uniformity of steric conditions at the site of radical attack. The rate constant for the addition of the ethyl radical is considered as an alternative to the copolymerization parameter Q0 as an index of the intrinsic reactivity of a monomer at a given temperature.

HYDROGEN ATOM ABSTRACTION BY ETHYL-d5 RADICALS. PART I

1960 ◽  
Vol 38 (9) ◽  
pp. 1576-1589 ◽  
Author(s):  
P. J. Boddy ◽  
E. W. R. Steacie
Keyword(s):  
Hydrogen Atom ◽  
Hydrogen Abstraction ◽  
Deuterium Atom ◽  
Structural Features ◽  
Activation Energies ◽  
Hydrogen Atom Abstraction ◽  
Kcal Mole ◽  
Temperature Range ◽  
Exponential Factors ◽  
Ethyl Radicals

The photolysis of 3-pentanone-d10 has been used as a source of deuterated ethyl radicals and some of their hydrogen abstraction reactions studied over the temperature range 50–300 °C.The compounds neopentane, n-butane, and isobutane were chosen as representative of the basic structural features in the alkane series. The activation energies for abstraction [Formula: see text] are respectively 12.60 ± 0.7, 10.4 ± 0.75, and 8.9 ± 0.6 kcal/mole and the pre-exponential factors (log10(A8/A4)) are 0.300 ± 0.09, 0.082 ± 0.09, and −0.334 ± 0.066 where[Formula: see text]For abstraction of a deuterium atom from the ketone the values obtained are [Formula: see text] in agreement with previous investigations (1, 2).The value of the disproportionation to combination ratio for C2D5 radicals is 0.0985 ± 0.008 independent of temperature.

Chemisorption of hydrogen on nickel–magnesia catalysts. Part I. General kinetic characteristics

1969 ◽  
Vol 47 (16) ◽  
pp. 2933-2941 ◽  
Author(s):  
N. S. Viswanathan ◽  
L. M. Yeddanapalli
Keyword(s):  
Experimental Data ◽  
Nickel Catalysts ◽  
Activation Energies ◽  
Effect Of Temperature ◽  
Hydrogen Chemisorption ◽  
Kinetic Characteristics ◽  
Wide Range ◽  
Elovich Equation ◽  
Kinetics Of

A detailed study of the kinetics of hydrogen chemisorption on 3 different nickel catalysts, supported on magnesia and prepared by coprecipitation, has been made over a wide range of pressures and temperatures. The results have been analyzed in the light of the Elovich equation. Experimental data obtained by variations of pressure and temperature indicate the existence of a number of stages in the chemisorption process and support the multiple kinetic stage hypothesis suggested by Low. The effect of temperature on the parameters has been studied, and relations obtained which have been used to calculate activation energies for each of the stages.

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