The conversion of ethanol over 3d-metal saponite-like smectites

Abstract

The replacement of fossil fuel processes with renewable pathways is critical to circumvent climate change and environmental risks. A process of interest is the production of 1,3-butadiene (BD), which is primarily derived as a by-product of naphtha steam cracking. A sustainable alternative path involves converting renewable ethanol to BD via the Lebedev process, which requires a catalyst with balanced redox, acidic, and basic sites. Due to the necessity of a multifunctional catalyst, existing materials for this reaction are either compirsed of catalyst mixtures or supported catalysts. In this study, we introduce a bulk material, saponite, containing M–O–Si sites, which combine required catalytic sites for the ethanol to BD (ETB) reaction in one material. The product composition in ethanol conversion were strongly dependent on the type of 3d-metal used, while no conclusive correlation between surface properties, conversion, and product composition was observed. Herein, using V-Sap*, we achieved an ethene productivity of 448 g_ethene kg_cat⁻¹ h⁻¹ (74%) at 573.15 K. High acetaldehyde productivity was maintained with Cu-Sap* (466 g_AcA kg_cat⁻¹ h⁻¹, 49%) at 573.15 K and Zn-Sap (528 g_AcA kg_cat⁻¹ h⁻¹, 55%) at 723.15 K. Mg-Sap primarily produced ethene but also yielded 10 g_BD kg_cat⁻¹ h⁻¹ BD at 723.15 K. Higher BD outputs were observed with Ni-Sap (31 g_BD kg_cat⁻¹ h⁻¹ at 523.15 K) and Mn-Sap* (51 g_BD kg_cat⁻¹ h⁻¹ at 723.15 K). This underscores the potential of saponite-based materials for flexible product outputs in ethanol conversion, influenced by the choice of integrated 3d-metal.