The Effect of Ambient Pressure on Catalytic Reaction over Platinum

A surface reaction occurs at a certain surface temperature when the catalyst is heated up in a reactive mixture. If homogeneous ignition does not occur, a steady state is observed because the heat produced by the surface reaction is balanced with the heat loss caused by convection, conduction and radiation. The steady temperature was defined as the temperature at the steady state. This paper treated the pressure effects on the surface reaction. Hydrogen and oxygen were used as reactants and nitrogen as an inert gas. A spherical platinum catalyst of 1.5 mm in diameter was sustained in the chamber with two wires of 0.1 mm in diameter. As results, there was a maximum steady temperature at a certain relative hydrogen concentration (α_<max>) and α_<max> increased with the total pressure. At the steady state, it could be approximated that the heat release was estimated by the mass transfer considering the effect of natural convection. The experimental results could be explained qualitatively by the approximation.