Defective zirconia promotes monometallic iron catalysts for higher alcohol synthesis

Efforts spanning decades toward the implementation of direct synthesis of higher alcohols from syngas have been unfruitful. Progress is hindered by insufficient understanding derived from catalyst complexity, as the need for different functionalities usually requires combining various metals, promoters, and supports. We reveal that iron becomes a remarkable catalyst when promoted by zirconia. Iron with 10 mol % ZrO2 achieves a space-time yield of 250 mgHA h−1 gcat−1 and 30% selectivity to higher alcohols at their optimized conditions, superior to reported monometallic Fe catalysts and comparable to state-of-the-art multimetallic materials. This catalyst, with an outstanding balance between performance and simplicity, was examined via operando X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Oxygen vacancy formation and healing in amorphous ZrO2 clusters enhance H2 and CO activation and Fe5C2 formation in contact with Fe3O4. Activity-composition correlations suggest this Fe3O4-Fe5C2 interface as the active phase. Promoted monometallic iron emerges as a promising platform for future generations of catalysts. [Display omitted] •Unique role of ZrO2 as a promoter for iron in higher alcohol synthesis•Superior performance to other monometallic catalysts comparable to multimetallics•Dynamic evolution of iron species and defective ZrO2 monitored by operando methods•Fe3O4-Fe5C2 interface determined as the active phase for higher alcohol synthesis The annual production of higher alcohols has reached hundreds of millions of tons and continues to grow based on the processing of olefins derived from fossil fuels. The increasing maturity of technologies capable of generating renewable carbon monoxide and hydrogen is boosting interest in directly synthesizing higher alcohols from syngas. However, decades of catalyst development efforts have not allowed implementation. Progress has been hampered by the traditionally complex catalyst formulations needed to develop this multistep reaction, leading to insufficient understanding to develop effective catalyst design guidelines. This work presents an efficient catalyst solely composed of iron and zirconia that shows a privileged combination of performance and simplicity. Extensive ex situ and operando characterization revealed structure-property-performance relationships that set the basis for rationally building complexity toward future highl