Multifunctional long-lived catalysts for direct hydrogenative conversion of CO2 to liquid hydrocarbons with upscaling C5+ productivity

Abstract

The direct hydrogenative conversion of inexpensive CO₂ to value-added liquid hydrocarbons with high economic value and chemical potential is an important pathway for realizing carbon neutrality and thereby mitigating climate change, but it is challenging owing to the high inertness of CO₂ and the high activation barrier associated with C–C coupling. Herein, we report a highly active, selective, productive, and stable multifunctional K-promoted Fe/CuAl₂O₄ catalyst, which achieved exceptional performance for the production of C₅₊ hydrocarbons with a record productivity of 429.4 mL g_cat⁻¹ h⁻¹ with a low CO selectivity of 10.2% at a CO₂ conversion of 41.9%. The C₅₊ productivity was further enhanced to 565.0 mL g_cat⁻¹ h⁻¹ at a faster feeding rate, while preserving the product distribution and catalyst longevity. Comprehensive spectroscopic characterization of the catalysts and controlled reaction studies indicated that interfacial contact between the various active phases in the catalysts and their amphoteric properties result in a synergistic effect on the consecutive activation of the reverse water–gas shift (RWGS) and Fischer–Tropsch synthesis (FTS) reactions. The active phases of the catalysts are present in a balanced composition, while the amphoteric properties of the catalyst are controlled by the addition of K to the nanocrystalline mesoporous architecture of the catalyst. The RWGS active sites partially reduce CO₂ to CO that is consecutively hydrogenated further on the FTS active sites. During the CO hydrogenation step, carbon chain growth on the Fe-based catalytic sites via C–C coupling is promoted by K-addition, resulting in a high C₅₊ hydrocarbon productivity. These catalytic components interact rigidly in proximity, which results in a highly sustainable performance without catalyst deactivation occurring for 10 d.