A kinetic study on the non-oxidative methanol conversion into formaldehyde and hydrogen over multiwall carbon nanotubes

Nonoxidative methanol conversion to formaldehyde and hydrogen is an important process. Formaldehyde is a valuable chemical both in itself and as a precursor, whereas hydrogen is a novel clean fuel. In this paper, the kinetics of the corresponding process was studied experimentally using multiwall carbon nanotubes as a catalyst. The carbon nanotubes demonstrated catalytic activity at temperatures as low as 443 K and 100% selectivity to desired products. A set of kinetic schemes for the methanol dehydrogenation to formaldehyde and hydrogen was established under Langmuir–Hinshelwood formalism. After the evaluation of the kinetic parameters, the kinetic scheme based on the dual-site Langmuir–Hinshelwood mechanism with the loss of the first hydrogen atom as a rate-determining step was found to be suitable in the experimental scenario. The identified kinetic model may correspond to either the alkoxy or hydroxyalkyl route of the methanol decomposition. To the best of our knowledge, this is the first experimental study reporting on the kinetics of the methanol conversion to formaldehyde and hydrogen over multiwall carbon nanotubes.