Preparation of Fe/SAPO-34 catalyst and its performance in CO hydrogenation to light olefins

Fischer-Tropsch synthesis is an important route to synthesize light olefins from syngas. However, precise control of the product selectivity and enhancing carbon utilization efficiency are still challenging. Herein, we prepared a series of Fe/SAPO-34 catalysts with different Fe contents using negative pressure impregnation method, and evaluated their performance in the CO hydrogenation reaction. Combined N₂ adsorption/desorption, XRD, SEM, NH₃-TPD, and CO-TPD characterizations, the structure−performance relationships of the Fe/SAPO-34 catalysts were clarified. It is found that with the increase of Fe loading, the strength and quantity of the acidity of the catalysts decreased sequentially, while the CO non-dissociation activation ability weakened and the CO dissociation activation ability increased, resulting in an increasing and decreasing trend in the selectivity of light olefins and oxygenates, respectively. Under a mild reaction conditions of 200 ℃, 2.0 MPa, GHSV=3300 h⁻¹, in the carbon products including CO₂, the selectivity of light olefins and oxygenates of the 5%Fe/SAPO-34 catalyst is 16.2% and 52.6%, respectively; while that of 25%Fe/SAPO-34 catalyst is 31.9% and 16.9%, respectively. A reasonable reaction mechanism is proposed based on the in situ IR characterization. This study provides a new way for the research and development of the catalyst for light olefins synthesis with enhanced carbon utilization efficiency, showing good application prospects.