Synergy effects of In2O3 promoter on an ordered mesoporous Cu/Al2O3 structures were verified in terms of CO2 hydrogenation to oxygenates by controlling a competitive reverse water gas shift (RWGS) reaction activity resulted in altering product distributions. The contiguously interacted smaller In2O3 on the Cu-Al2O3 matrices at an optimal In/Cu ratio of ∼ 0.01 (InCu/mAl(1)) played important roles to enhance CO2 activation with its lower activation energy (∼15.6 kJ/mol) as well as to stabilize the spatially confined Cu nanoparticles by decreasing the formations of less active CuAl2O4 phases. On the optimal InCu/mAl(1), the oxygen vacant sites originated from Cu-In2O3 interfaces under reductive environments largely accelerated CO2 dissociation to form HCOO formate intermediate by suppressing RWGS reaction activity, where the formate intermediates can be further hydrogenated to oxygenates on the metallic Cu or Cu2O sites as well as dimethyl ether (DME) on the acidic sites via successive cascade reaction. However, an excess amount of In2O3 (ln/Cu ratio above 0.03) on the Cu-Al2O3 matrices decreased the catalytic activity due to severe blockages of the more active metallic Cu sites with an increased oxygenates selectivity such as methanol (CH3OH) and dimethyl ether (DME). The positive roles of oxygen-vacant Cu-In2O3 sites on the mesoporous Cu-Al2O3 structures were to effectively activate CO2 molecules to form formate and carbonate intermediates as well as to stabilize the more active partially reduced Cu phases with an enhanced hydrogenation activity to oxygenates.
|Journal||Chemical Engineering Journal|
|Publication status||Published - 2022 Jul 1|
Bibliographical noteFunding Information:
This research was supported by the Korea Electric Power Corporation of the Republic of Korea (Grant number: R21XA01-29) and the authors would sincerely like to acknowledge the financial support from the National Research Foundation of Korea (NRF) grant funded by the South Korea government (NRF-2018M3D3A1A01018009). The authors also appreciate the sincere contributions of Dr. S. H. Choi working at Pohang Accelerator Laboratory (PAL) for X-ray adsorption spectroscopy (XAS) analysis with a synchrotron accelerator.
© 2022 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering