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

Abstract

A high-performance Ni-foam-structured FeNi3-FeOx 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-FeOx/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 WHSVDMO 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 FeOx 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.