An environmentally benign and catalytically efficient non-pyrophoric Ni catalyst for aqueous-phase reforming of ethylene glycol

Abstract

A non-pyrophoric Ni catalyst (NP Ni) was prepared by alkali leaching of a Ni₅₀Al₅₀ alloy using only ∼ 1/10 of the amount of NaOH required for the preparation of the conventional Raney Ni catalyst. Characterizations reveal that the as-prepared NP Ni catalyst can be looked at as a Ni–Al(OH)₃ composite catalyst with Ni in the metallic state and Al(OH)₃ in forms of gibbsite and bayerite. After 100 h on stream in aqueous-phase reforming (APR) of ethylene glycol, phase transformation of gibbsite and bayerite to flake-like boehmite occurred, along with the growth of Ni crystallites and partial oxidation of metallic Ni to Ni(OH)₂. Under identical reaction conditions for APR of ethylene glycol, the NP Ni catalyst is about 40–52% more active than Raney Ni in terms of the conversion of ethylene glycol to gas products, which is attributed to the stabilizing effect of hydrated alumina on Ni crystallites. The higher selectivity toward H₂ and the lower concentration of CO in the product gas on the NP Ni catalyst are attributed to the activation of water by hydrated alumina which is beneficial to the water-gas shift reaction.