Region of multiplicity of stationary states in the oxidation of carbon monoxide over platinum

1981 ◽  
Vol 16 (4) ◽  
pp. 375-379 ◽  
Author(s):  
V. I. Bykov ◽  
Yu. G. Zarkhin ◽  
G. S. Yablonskii

The oxidation of carbon monoxide in equimolar mixtures (CO + O 2 ) has been studied in a well-stirred open system (0.5 dm 3 ) at vessel temperatures in the range 700-840 K, and reactant pressures up to 100 Torr ( ca . 13.3 kPa) at a mean residence time of 8.5 s. Stationary states are established and oscillatory states sustained indefinitely in this system. The effect of small quantities of added hydrogen is studied by a carefully controlled, continuous supplement to the principal reactants. Four different modes of reaction (I-IV) have been characterized, and conditions for their occurrence mapped on a reactant pressure-vessel temperature ( p - T a ) ignition diagram. Most boundaries are quite sharp, and some show evidence of hysteresis. Close to the axes, reaction is slow, non-luminous and non-oscillatory (I). Within a first broad promontory (II) reaction is accompanied by steady luminescence. Crossing the boundary is not accompanied by a step change in reaction rate, but there is a change in character from stable node (in I) to stable focus (in II). Auto-oscillatory luminescence occurs in a closed region (III) wholly within the promontory II. The effects of adding hydrogen on all these modes is to increase the reaction rates markedly and to make them non-isothermal; the boundaries between I, II and III are not as greatly affected. However, systems to which more than 0.10% H 2 have been added also display a new mode, of oscillatory ignition. This appears at first in a region (IV) of high temperatures and pressures but as more H 2 is increased its realm expands and it eventually dominates the ignition diagram, invading the region of luminescence and soon obliterating the oscillatory part completely.


Author(s):  
Thulani M. Nyathi ◽  
Mohamed I. Fadlalla ◽  
Nico Fischer ◽  
Andrew P.E. York ◽  
Ezra J. Olivier ◽  
...  

2011 ◽  
Vol 16 (2) ◽  
pp. 587-595 ◽  
Author(s):  
Maja D. Obradović ◽  
Amalija V. Tripković ◽  
Snežana Lj. Gojković

Sign in / Sign up

Export Citation Format

Share Document