The mechanism of the heterogeneous catalytic polymerization of ethylene oxide

Крылов, О. В.; Kushnerev, M.Ya.; Markova, Z.A.; Fokina, E. A.

doi:10.1016/0032-3950(65)90384-9

Cited by 2 publications

(2 citation statements)

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“…The successive adsorption experiments using 13 CO 2 for the MgO sample revealed another aspect of the dynamic behavior of carbonate species on the surface. Krylov et al reported the results of successive adsorption experiments using radioisotopic 14 CO 2 in their study of MgO . They observed that a 14 CO 2 concentration was proportional to the total CO 2 remaining on the surface after desorption at each temperature whenever 14 CO 2 was adsorbed first or secondarily at 50 °C.…”

Section: Discussionmentioning

confidence: 99%

Dynamic Behavior of Carbonate Species on Metal Oxide Surface: Oxygen Scrambling between Adsorbed Carbon Dioxide and Oxide Surface

et al. 2003

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The oxygen exchange between surface carbonate species and oxide surfaces was investigated by the temperature-programmed desorption (TPD) of C18O2 adsorbed on metal oxides, MgO, CaO, and ZrO2 at room temperature. Although desorption plots were quite different for these metal oxides, extensive oxygen exchange was commonly observed. The fraction of C16O2 in the total desorbed CO2 increased monotonically with desorption temperature, and each desorption peak in the plots for the total CO2 could not be characterized by the isotopic distribution. The difference in proportion of incorporated lattice oxygen in the total CO2 at each desorption temperature was small between the low and high concentrations of C18O2. Among these metal oxides, ZrO2 showed the highest fraction of C16O2 in the total CO2 desorbed at 400 °C when C18O2 was adsorbed on these metal oxide with same surface concentration. The value of [C16O18O]2/{[C16O2][C18O2]} was close to 4 over almost all the temperature region of desorption for all these metal oxides, indicating that the three oxygen atoms composing carbonate were entirely scrambled before desorption as CO2. The amount of fixed monodentate carbonate with no exchange of oxygen was quite small. The manner of surface lattice oxygen incorporation into carbon dioxide is discussed on the basis of the mechanism proposed in the previous study. Successive adsorption experiments using 13CO2 with MgO demonstrated that the carbonate species switches from the weak basic sites to the strong basic sites during the heating process. It was also suggested that the dynamic behavior of carbonate species varies the coordinative environment and the adsorption strength of basic sites, which results in their further migration and desorption as CO2.

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Section: Discussionmentioning

confidence: 99%

Dynamic Behavior of Carbonate Species on Metal Oxide Surface: Oxygen Scrambling between Adsorbed Carbon Dioxide and Oxide Surface

et al. 2003

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“…The overall reaction rate V of eq 11 can be obtained from y = -dnco/dt (12) Combination of eq 2,11, and 12 gives -=1 -(ZC02 -2co)(^/»co^) (13) For the direct use of experimental data the following equation may be more advantageously employed where pco denotes the partial pressure of carbon monoxide in the system. The overall net reaction rate V is also given in terms of u+i and u_i, that is V = -dpCo/di = u + i -u_i (15) Note that eq 14 and 15 may be solved simultaneously to give the values of u + , and u-¡ for various experimental conditions.…”

Section: Mathematical Analysismentioning

confidence: 99%

Mechanistic structure of the water-gas shift reaction in the vicinity of chemical equilibrium

Oki¹,

Mezaki²

1973

J. Phys. Chem.

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The mechanistic study of the water-gas shift reaction over an iron oxide catalyst was made utilizing the isotopic exchange reaction of oxygen-18. Reaction temperatures ranged from 400 to 450°and the total pressure of the reaction system was 80 mm. The forward and backward rates of the rate-determining steps of the reaction, that is, CO s=t CO (a) (step i) and 2H (a) <=* H2 (step v) were computed and compared. The comparison indicated that the order of magnitude of the forward rate of step i is comparable with that of the forward rate of step v and that in the early stage of the reaction, step v would govern the overall rate, whereas step i becomes the governing step as the reaction progresses to approach the chemical equilibrium. The results are in good agreement with those of earlier investigations.

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The mechanism of the heterogeneous catalytic polymerization of ethylene oxide

Cited by 2 publications

References 5 publications

Dynamic Behavior of Carbonate Species on Metal Oxide Surface: Oxygen Scrambling between Adsorbed Carbon Dioxide and Oxide Surface

Dynamic Behavior of Carbonate Species on Metal Oxide Surface: Oxygen Scrambling between Adsorbed Carbon Dioxide and Oxide Surface

Mechanistic structure of the water-gas shift reaction in the vicinity of chemical equilibrium

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