Direct Conversion of Syngas to Ethanol within Zeolite Crystals

Abstract

Summary The direct transformation of syngas into C2-oxygenates (e.g., ethanol) is in great demand, but it is still challenging because of the low selectivity and poor catalyst stability. Here, we overcome the issues and report a zeolite-fixation methodology to strengthen the transformation. By employing the extensively investigated RhMn catalyst, the silicate-1 zeolite-fixed RhMn nanoparticles with core-shell structure (RhMn@S-1) exhibit high efficacy for the C2 oxygenates production from syngas, giving oxygenate selectivity at 40.3% under CO conversion of 42.4% (C2-oxygenate selectivity at 88.3% in the total oxygenates), which decidedly outperforms the previous catalysts in direct syngas-to-ethanol transformation. Multiple studies demonstrate that the rigid zeolite framework efficiently stabilizes the Mn-O-Rhδ+ structure, known as the crucial site for C2-oxygenate formation. In the long-term test, the RhMn@S-1 catalyst exhibits constant C2-oxygenate productivities with superior durability. This investigation demonstrates the powerful siliceous zeolite support in the C2-oxygenate production, which has not been explored previously.