A Highly Stable Copper-Based Catalyst for Clarifying the Catalytic Roles of Cu0 and Cu+ Species in Methanol Dehydrogenation

Identification of the active copper species, and further illustration of the catalytic mechanism of Cu-based catalysts is still a challenge because of the mobility and evolution of Cu-0 and Cu+ species in the reaction process. Thus, an unprecedentedly stable Cu-based catalyst was prepared by uniformly embedding Cu nanoparticles in a mesoporous silica shell allowing clarification of the catalytic roles of Cu-0 and Cu+ in the dehydrogenation of methanol to methyl formate by combining isotope-labeling experiment, in situ spectroscopy, and DFT calculations. It is shown that Cu-0 sites promote the cleavage of the O-H bond in methanol and of the C-H bond in the reaction intermediates CH3O and H2COOCH3 which is formed from CH3O and HCHO, whereas Cu+ sites cause rapid decomposition of formaldehyde generated on the Cu-0 sites into CO and H-2.