Catalytic steam reforming of methanol using a commercial copper oxide/zinc oxide/aluminum oxide low temperature shift catalyst (copper oxide, zinc oxide, aluminum oxide)

The steam reforming of methanol on a commercial CuO/ZnO/Al{dollar}sb2{dollar}O{dollar}sb3{dollar} low temperature shift catalyst, C18HC, was studied in a fixed bed reactor. Methanol conversions were measured at pressures of 101, 202 and 303 kPa at temperatures from 160 to 220{dollar}spcirc{dollar}C. Water to methanol molar ratios of 0.66, 1.0 and 1.5 were examined. The feed rate of methanol was varied to give reactor space times (based on the mass of catalyst) ranging from 60 to 620 s{dollar}cdot{dollar}kg of catalyst{dollar}cdot{dollar}mole of methanol{dollar}sp{lcub}-1{rcub}{dollar}. The kinetic model of Amphlett et al (1988) was found to be inadequate for predicting methanol conversions when the reactor pressure exceeded 101 kPa. The composition of the product gas was compared with the equilibrium constants for the various possible reactions. For all measurements the methanol conversion was found to be well below equilibrium with respect to the decomposition and steam reforming reactions. The product composition, however, was found to vary from above equilibrium to below equilibrium with respect to the water-gas-shift reaction. This result contradicts earlier proposals that the reaction could be viewed as the decomposition of methanol followed by the water-gas-shift reaction. The reaction scheme must include a direct path to carbon dioxide. All results showed catalyst deactivation occurred at a measurable rate contrary to the observations of earlier studies. Lastly it was found that the design of the experimental apparatus resulted in a significant degree of axial dispersion in the catalyst bed. These effects would result in a significant error for any estimate of kinetic parameters based on the assumption of plug flow.