Kinetic Study of Metal-Catalyzed Reaction of Solid Calcium Oxide with Gas Mixtures of Methane and Water Vapor to Form Hydrogen

With noble metal catalysts (Pd, Pt, Rh, Ir) present, hydrogen is formed by the interaction of solid calcium oxide with gas mixtures of methane and water vapor, according to CaO + CH4 + 2H2O → CaCO3 + 4H2. Among the metals, Ir and Rh are so active that the reaction takes place at temperatures as low as 600 K. Rate data obtained with these metals show a nearly first order with respect to CH4 pressure, while a negative order with respect to H2O vapor pressure. The apparent activation energies are 171 and 217 kJ/mol for the Ir- and Rh-catalyzed reactions, respectively. On the other hand, Ni does not catalyze the reaction below 733 K, probably due to its strong interaction with H2O vapor.