Kinetic modeling of the production of hydrogen from the methanol-steam reforming process over Mn-promoted coprecipitated Cu-Al catalyst

Kinetic studies were performed using a manganese-promoted coprecipitated Cu-Al catalyst at reaction temperatures in the range 170-250 degrees C and space time ranging from 0.1 to 2.5 g cat h/mol CH,OH to examine the influence of catalyst and reaction temperature on the rate-controlling mechanism of the methanol-steam reforming process for the production of hydrogen. Results showed the existence of two reaction temperature-dependent kinetic regions, thus highlighting a thermodynamic constraint on the participation of the redox property of the catalyst in the reaction. It was interesting to observe that methanol dissociation by O-H bond cleavage was the rate-determining step in the low reaction temperature region whereas in the high reaction temperature region, the rate-determining step switched to methyl formate hydrolysis. Empirical rate models as well as those based on the Langmuir-Hinshelwood approach using these rate-determining steps were developed for the two reaction temperature regimes. These models were able to describe the methanol-steam reforming process adequately for the respective temperature regimes. Copyright (C) 1996 Elsevier Science Ltd