Pressure Effects on Hydrogen-Oxygen Reaction over Platinum Catalytic Surface

Abstract

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 is defined as the temperature at the steady state. This paper treats the pressure effects on the surface reaction. Hydrogen and oxygen are used as reactants and nitrogen as an inert gas. The height, width and length of the combustion chamber are 76 mm, 140 mm and 140 mm, respectively. A spherical Pt catalyst sample of 1.5 mm in diameter is sustained in the chamber with two wires of 0.1 mm in diameter. As results, there is a maximum steady temperature at a certain equivalence ratio (ERmax) and ERmax increases with total pressure. At the steady state, it can be approximated that the heat release is evaluated by the mass transfer which includes the effect of natural convection. The experimental results could be explained qualitatively by the approximation.