Superior FeNi₃-FeO_x/Ni-foam catalyst for gas-phase hydrogenation of dimethyl oxalate to ethanol

A high-performance Ni-foam-structured FeNi₃-FeO_x nanocomposite catalyst is developed for the ethanol (EtOH) synthesis from syngas via gas-phase dimethyl oxalate (DMO) hydrogenation. The hydrothermally-synthesized Ni(OH)₂/Ni-foam was impregnated with aqueous solution of iron(III) nitrate, from which the preferred FeNi₃-FeO_x/Ni-foam-(550/350) catalyst was obtainable by calcining preferably at 550 °C (to adequately form NiFe₂O₄-NiO composites) and subsequently reducing in H₂. Such catalyst is capable of fully converting DMO with 98 % ethanol selectivity at 230 °C and 2.5 MPa using a WHSV_DMO of 0.44 h⁻¹ and a H₂/DMO molar ratio of 90, and particularly, being stable for at least 700 h. A high turnover frequency of 88.8 h⁻¹ is achieved at 180 °C. Exactly, our NiFe₂O₄-NiO derivation strategy endows the catalyst with plentiful interface between FeNi₃ nanoalloy (∼16 nm) and FeO_x fragments (acting as acid sites), achieving synergistic catalysis to ester groups in DMO and as-formed hydroxyl groups, thereby markedly improving its hydrogenation to EtOH.