Acid–base and redox performance of carbon nanotubes in methanol conversion

Abstract

This study presents the catalytic properties of multi-walled carbon nanotubes (MWCNTs) in the direct conversion of methanol. The high stability of MWCNTs at 550 °C, the formation of dimethyl ether and formaldehyde with a minor content of methane, and the principal possibility of methanol decomposition to H₂ and CO are demonstrated. Using 3 different MWCNTs with different structural parameters and surface functionalities highlights that the methanol conversion increases by increasing both surface oxygen content and defectiveness. DFT calculations were performed to deepen the understanding of the methanol dehydrogenation mechanism by evaluating the routes of methanol transformation on single and double vacancy defects. The obtained results reveal that methanol dehydrogenation can proceed on at least two different types of active sites. These results provide guidance to the design and more precise engineering of the structure of carbocatalysts, opening new perspectives for their application in catalysis.