Synergy induced by physical mixing m-ZrO2 and α-Ga2O3 for effective conversion of syngas to light olefins

The GaZrO x solid solution has been recently employed in OX-ZEO bifunctional catalysts for efficient conversion of syngas to light olefins, but it remains challenging to identify the specific contributions of Zr and Ga and to understand the detailed reaction mechanisms due to the structural complexity. To address this complexity and elucidate the active sites over the Zr-Ga oxide system, this study presents a catalyst designed by physical mixing ZrO 2 with different crystalline phases ( m -ZrO 2 & t -ZrO 2 ) and α -Ga 2 O 3 . The physical mixture of m -ZrO 2 and α -Ga 2 O 3 achieves a high CO conversion of 39.1 %, with light olefins selectivity of 87.3% among hydrocarbons after combined with SAPO-34, surpassing the performance of physical mixture of t -ZrO 2 and/or α -Ga 2 O 3 with SAPO-34. Combining the various characterizations and DFT calculations, we have confirmed that m -ZrO 2 site, enriched with oxygen vacancies and surface hydroxyl groups, is essential for CO adsorption and HCOO* intermediate formation, while the α -Ga 2 O 3 site plays a key role in the dissociation of H 2 . Furthermore, the electron transfer from m -ZrO 2 to α -Ga 2 O 3 in their mixture is more efficient than in a physically mixed t -ZrO 2 and α -Ga 2 O 3 . This accelerates the H 2 dissociation and boosts the spillover of hydrogen from α -Ga 2 O 3 to m -ZrO 2 , leading to the formation of more CH 3 O* intermediates and higher light olefins yield when combined with SAPO-34.