Kinetics of hydrogen-oxygen catalytic recombination at low oxygen levels and ambient temperature

Hydrogen is a promising energy carrier for low-carbon economies. However, when produced by electrolysis from intermittent renewable sources, oxygen impurities in hydrogen streams pose safety risks. This study examines the kinetics of the hydrogen–oxygen catalytic recombination reaction on Pd/Al2O3 catalysts to eliminate oxygen traces, particularly in high-purity hydrogen streams at ambient temperature (25 °C ± 1.5 °C) and atmospheric pressure. Catalytic testing was conducted in a plug flow reactor, measuring residual oxygen at steady state across different catalyst masses with a constant inlet oxygen concentration of 750 ppm. Based on a literature review, a pseudo-first-order kinetic model, with reaction rate as a function of O2 concentration, was selected to represent the system's behavior. Experiments were initially performed using two spherical “egg-shell” Pd/ Al2O3 catalysts (0.15 % w/w Pd) of different sizes to minimize internal diffusion resistance, enabling accurate estimation o...