Significantly boosting the production of higher alcohols from biomass-derived ethanol utilizing tandem catalysts integrating a NiO-modified Cu-based component with a Mg–Al–Zr mixed metal oxide

Abstract

The green, sustainable and efficient production of valuable higher alcohols from biomass-derived ethanol, which is commonly accomplished through cooperative catalysis for multi-step tandem reactions, is highly attractive but challenging in terms of alleviating energy shortages and achieving carbon neutrality. Herein, we engineered an innovative tandem catalyst by integrating a NiO-modified Cu-based component (Cu–NiO) with a Mg–Al–Zr mixed metal oxide component (MgAlZrO) for enhanced ethanol upgrading to higher alcohols. The as-combined tandem composite Cu–NiO∥MgAlZrO catalyst (∥ represents the physical mixing of the components Cu–NiO and MgAlZrO) with a tiny mass fraction of Cu–NiO (1.25 wt%) exhibited a high ethanol conversion (68.2%) and excellent total selectivity of higher alcohols (75.1%), along with a remarkably high space–time yield to higher alcohols (15.8 mmol g_cat⁻¹ h⁻¹) under mild reaction conditions (250 °C, 2 MPa, WHSV = 1.42 h⁻¹). The high catalytic efficiency of the composite catalyst was owing to the cooperative catalysis of multiple adjacent active sites that arose from favorable surface electron-rich Cu⁰ sites and interfacial Cu⁺–O–Ni²⁺ structures on Cu–NiO and considerable surface acid–base sites on MgAlZrO, which significantly promoted ethanol dehydrogenation and subsequent aldol condensation processes. Thus, this study provides a promising strategy for boosting the eco-friendly and sustainable production of higher alcohols from ethanol by developing tandem composite catalysts.