Selective production of acetonitrile via dehydroamination of ethanol over a stable Cu–Zr/meso SiO2 catalyst

Abstract

Production of acetonitrile from ethanol via the non-oxidative dehydroamination process provides an attractive route for converting biomass-derived substrates into high-value chemical compounds. Conventional copper-based catalysts exhibit excellent activity and product selectivity at low-temperatures (≤330 °C), but they suffer from the challenge of deactivation. Herein, a binary Cu₁₀–Zr₂/meso SiO₂-UP catalyst was prepared via a facile urea-assisted precipitation method for ethanol dehydroamination to acetonitrile. Under the optimal reaction condition (265 °C, ethanol WHSV of 0.8 h⁻¹ and NH₃/ethanol molar ratio of 9), 95% product selectivity for acetonitrile with over 90% ethanol conversion was realized and maintained for more than 116 h, which was 48-fold longer than that of the conventional counterpart. According to the systematic characterizations, the introduction of Zr exhibited multifunctionality by (1) enhancing the copper species dispersion, (2) preventing the Cu nanoparticle from sintering, (3) adjusting the Cu⁺/Cu⁰ ratio, (4) modifying the acidity, and (5) regulating the adsorption–desorption behavior of the organics. The apparent activation energy (Ea) for ethanol conversion dropped by 22.3 kJ mol⁻¹, from 69.3 kJ mol⁻¹ over the conventional monometallic catalyst to 47.0 kJ mol⁻¹ over the as-prepared Cu–Zr binary catalyst. Notably, the catalyst demonstrated excellent substrate compatibility in transforming a series of aliphatic alcohols and benzyl alcohol into the corresponding nitriles with over 85% yields.