ARE THE EQUILIBRIUM CONCENTRATIONS OF CO AND H-2 EXCEEDED DURING THE OXIDATION OF CH4 OVER A NI YB2O3 CATALYST/

A combination of high space velocities, a very exothermic reaction, an d an active catalyst gives rise to large temperature gradients, or hot spots, during the catalytic oxidation of CH4 to CO and H-2. These hot spots have been detected visually and with an optical pyrometer durin g the oxidation reaction over a Ni/Yb2O3 catalyst. The temperature of the hot spot may be as much as 300-degrees-C greater than the temperat ure measured by a thermocouple located only a short distance from it i n the catalyst bed. If the lower temperature is used to calculate the equilibrium concentrations of CH4, CO, CO2, and H-2, it is possible to reach the conclusion that the concentrations of CO and H2 exceed thei r thermodynamic equilibrium values. But if the true maximum (hot spot) temperature is used, the observed concentrations are somewhat less th an those predicted at equilibrium.