Temperature-programmed desorption study of water-gas shift and methane steam-reforming reactions over Li/MgO catalyst Original Research Article

The water-gas shift (WGS) and methane steam-reforming (MSR) reactions over 1% Li/MgO catalyst were investigated using thermal-programmed desorption (TPD) technique with isotope labelled compounds (C16O, H218O, C16O and CD4). The experimental results show that WGS reaction over 1% Li/MgO catalyst takes place in the temperature range 400–800 K following a Langmuir–Hinshelwood mechanism. The highest reaction rate was observed at 617 K and the estimated activation energy, from the desorption peak of reaction product, is 158 kJ/mol. The experimental results suggest that the contribution of WGS side reaction to the total amount of CO2 and H2, formed in the oxidative coupling of methane (OCM), is important.The MSR reaction between CD4 and water over Li/MgO catalyst could not be evidenced by TPD method due to the weak adsorption of CD4. However, a room-temperature isotope exchange between CD4 and the hydroxyl groups of 1% Li/MgO could be observed.