Ethanol dehydrogenation to acetaldehyde with mesoporous Cu-SiO2 catalysts prepared by aerosol-assisted sol-gel

Copper based catalysts are central for carrying dehydrogenation reactions. However, these materials are prone to deactivation by sintering and coke deposition. Irreversible sintering occurring during reaction (under the effect of temperature) is known to decrease both activity and selectivity, where the unwanted dehydration activity of the support might also play an important role. From this perspective, the quite unreactive silica supports may be attractive. However, using classical catalyst preparation methods (e.g. impregnation), it is a challenge to obtain a stable and homogeneous dispersion of Cu over SiO2 owing to the weak support-active phase interactions. Taking a sidestep, aerosol-assisted sol-gel is a promising alternative for the facile preparation of mesostructured metallosilicates with high metal dispersion. Here we report, for the first time, Cu-SiO2 made by the aerosol-assisted sol-gel method and exploited in the ethanol non-oxidative dehydrogenation to acetaldehyde. These catalysts are compared with a series of catalysts made by impregnation to investigate, through a thorough characterization survey, the effect of the synthesis procedure as well as the effect of Cu loading. We show that aerosol-made catalysts do not suffer heavy sintering, reach high ethanol conversions with acetaldehyde selectivity above 75%, and only slowly deactivate upon time due to a (reversible) coking phenomenon.