Catalytic activity for direct CO2 hydrogenation to dimethyl ether with different proximity of bifunctional Cu-ZnO-Al2O3 and ferrierite

CO2 to dimethyl ether (DME): structural and functional insights of hybrid catalysts

“…However, in the RWGS mechanism, the first HOCO* species is formed followed by successively hydrogenated to H 3 CO*. The formation of HOCO* species is found to be the rate-limiting state over the Cu (111) 58 They came up with spectroscopy information that supports, the formation of methanol occurs either through formate or through reverse water-gas shift (RWGS) mechanisms over CuO-ZnO-ZrO 2 /H-ZSM-5. However, a different mechanism i.e., the carbonate mechanism comes into play on the oxidized Cu (δ + ) surface.…”

“…136 The performed calculation indicates that the Ga doping not only promotes the adsorption of CO 2 and intermediates but also favors the methanol formation through the formate pathway. The required applied potential for Ga doped surface is the lowest for the hydrogenation of *HCOO → *HCOOH intermediate among Zn doped and undoped CuAl 2 O 4 (111) surfaces. As reported, the process of methanol to DME via the dissociative pathway is unfavorably compared to the associative pathway due to the highly endergonic nature of dissociative coupling with second methanol.…”

“…The actual discussion, therefore, focuses on elucidating the mechanistic pathways for the activation of reactants (such as CO 2 and H 2 ) with clear evidence for the formation of intermediate or spectator species prior to methanol synthesis. Methanol can be produced from CO 2 over Cu (111) in two different ways: via a formate intermediate and by CO hydrogenation mediated by reversible water-gas shift (RWGS). A theoretical study suggests that the formate mechanism proceeds through hydrogen spillover from metallic Cu (111) to preactivated CO 2 leading to the formation of monodentate (m-HCOO*) or bidentate formate (b-HCOO*) species 78 (Fig.…”

“…Methanol can be produced from CO 2 over Cu (111) in two different ways: via a formate intermediate and by CO hydrogenation mediated by reversible water-gas shift (RWGS). A theoretical study suggests that the formate mechanism proceeds through hydrogen spillover from metallic Cu (111) to preactivated CO 2 leading to the formation of monodentate (m-HCOO*) or bidentate formate (b-HCOO*) species 78 (Fig. 5).…”

“…12). 111 Therefore, they suppressed the ion exchange process by introducing a physically coated interlayer of SiO 2 to synthesize a core-shell Cu-ZnO-Al 2 -O 3 @FER catalyst. About 40 μm SiO 2 can create suitable micrometer-scale proximity between the metal oxide and the FER zeolite for obtaining a stable and best performance up to 100 h. This layer prevents the movement of metal ions for the solid-state ion exchange reaction and also creates a more hydrophobic ZnO-rich surface.…”