Development of Highly Selective Support for CO Hydrogenation to Light Olefins with Partially Passivated Iron Catalysts

To rule out disturbances from water‐soluble efficient promoters (e. g., K 2 O or combination of S/Na), a simplified iron/support catalyst system was employed to investigate novel supports for the catalytic conversion of syngas (CO+H 2 ) to light olefins (FTO). A series of supports with nominal compositions of ZnAl 2 O 4  ⋅  x Al 2 O 3 ( x =1, 2, 3) were prepared by coprecipitation and subsequent high temperature calcination at 1200 °C for 24 h to generate partially passivated ZnAl 2 O 4 and Al 2 O 3 phases, through which each formed component of a catalyst may minimize interactions among them and exhibit unique activity. Iron catalysts were prepared by incipient wetness of iron salts over these supports. At a total pressure of ca. 20 bar and a CO conversion of 35 %, a catalyst with a nominal composition of 15 %Fe/85 %(ZnAl 2 O 4  ⋅ 3Al 2 O 3 ) exhibits a surprising C 2 = ‐C 4 = hydrocarbon distribution of 58 %, which reaches a huge increase by almost 100 % in comparison with iron catalysts over regular supports (e. g., carbon, gamma‐Al 2 O 3 , etc.). This catalyst demonstrates the 1200 °C passivated ZnAl 2 O 4  ⋅ 3Al 2 O 3 as probably the most selective support material for iron‐based FTO catalysts. At CO conversion of 35 %, the contents of ethylene in C 2 , propylene in C 3 , and butylene in C 4 products achieve extraordinary values of 82 %, 92 %, and 91 %, respectively.