Kinetics study on the catalytic recombination of non-premixed hydrogen–oxygen system: Effects of initial temperature, oxygen flow rate, and hydrogen diffusion time

Abstract

Hydrogen-oxygen catalytic recombination reaction, as a promising technology for hydrogen elimination in the confined environment, can spontaneously eliminate the leaking hydrogen in the environment. However, the kinetics characteristics of this reaction process under different environmental factors have been poorly reported. A series of hydrogen–oxygen catalytic recombination experiments are performed in a little cylindrical container using Platinum-Carbon powder as the catalyst, to investigate the effects of the initial temperature, oxygen flow rate, and hydrogen diffusion time on the temperature characteristics. In addition, the amount of residual hydrogen at the end of the reaction is also taken into account. The results show that the reaction intensity increases with the increase of the initial temperature, and the first temperature peak PT1 is gradually smaller than PT2 and finally disappears. However, the intensity of temperature increase caused by the reaction exotherm does not enhance continuously with the increase of the reaction intensity. With the decrease in oxygen flow rate, the reaction temperature gradually reduces and the temperature peak gradually forms before the end of oxygen inflow. Nevertheless, the direction of temperature transfer is hardly affected by the oxygen flow rate and the heat is still accumulating below the catalyst. The effect of hydrogen diffusion time on the reaction at hydrogen-poor, stoichiometric ratio hydrogen, and hydrogen-rich is diverse and complex, but the temperature–time profile on the catalyst surface has been changed accordingly. In addition, under any conditions, the hydrogen can be completely reacted below the stoichiometric ratio.