Defective zirconia promotes monometallic iron catalysts for higher alcohol synthesis
Yuzhen Ge, Tangsheng Zou, Antonio J. Martín, Theresa Block, Rainer Pöttgen, Javier Pérez‐Ramírez
Abstract
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 % ZrO 2 achieves a space-time yield of 250 mg HA h −1 g cat −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 ZrO 2 clusters enhance H 2 and CO activation and Fe 5 C 2 formation in contact with Fe 3 O 4 . Activity-composition correlations suggest this Fe 3 O 4 -Fe 5 C 2 interface as the active phase. Promoted monometallic iron emerges as a promising platform for future generations of catalysts.