Unraveling the Roles of Individual Metals in Bifunctional Catalysts Zn x Cr y Mn z /SAPO-34 for Boosting Syngas Conversion to Light Olefins

The direct conversion of syngas to light olefins (STO) over a metal oxide-zeolite bifunctional catalyst has been recognized as a breakthrough development, but the bottleneck of low CO conversion efficiency still exists. Herein, we stepwise develop binary and ternary metal oxides of Zn x Cr y Mn z to reveal the roles of individual metals. Through theoretical prediction and in situ characterizations, the produced Cr1Mn1.5O4 spinel by Cr doping exhibits a higher concentration of oxygen vacancies, correlating with higher CO adsorption and catalytic activity, whereas further Zn incorporation generates the satellite ZnCr2O4 spinel around Cr1Mn1.5O4 spinel, giving higher H2 dissociation capability and extra oxygen vacancies. Coupling with SAPO-34, a stable CO conversion efficiency as high as 60.4% at the C2–C4 olefin selectivity of 76.4% is dramatically achieved during a long-term test of 160 h in the fixed bed of granulated Zn0.10Cr0.36Mn0.54/SAPO-34, providing a promising industrial application future of this STO approach.