Copper‐Fiber‐Structured Pd–Au–CuO_x: Preparation and Catalytic Performance in the Vapor‐Phase Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

Abstract

Cu‐fiber‐structured ternary Pd–Au–CuOx catalysts engineered from nano‐ to macro‐scales have been developed for the vapor‐phase dimethyl oxalate (DMO) hydrogenation to ethylene glycol (EG), with the aid of galvanic deposition of Pd and Au onto a thin‐sheet microfibrous structure using 8 μm Cu fiber. Effects of Pd and Au loadings and their ratio have been investigated on the catalyst performance as well as the reaction conditions including reaction temperature and pressure, liquid weight hourly space velocity, and H2/DMO ratio. The promising 0.1 Pd–0.5 Au–CuOx/Cu‐fiber catalyst is capable of converting 97–99 % DMO into EG product at a selectivity of 90–93 %. This catalyst is stable for at least 200 h. The Pd–Au–Cu2O synergistically promotes the hydrogenation activity and stabilizes Cu+ sites to suppress deep reduction deactivation.

Importance of the Initial Oxidation State of Copper for the Catalytic Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

“…Han et al. reported Pd‐Au‐CuO x prepared through the galvanic deposition of Pd and Au onto a thin‐sheet, microfibrous structure by using 8 mm Cu fibers, which synergistically promoted the hydrogenation activity and stabilized the Cu + sites . Zhang et al.…”

“…Han et al reported Pd-Au-CuO x prepared through the galvanic deposition of Pd and Au onto at hin-sheet, microfibrous structure by using 8mmC uf ibers, which synergistically promoted the hydrogenation activity and stabilized the Cu + sites. [7] Zhang et al reported ap lasma-treated Cu-Ni/ZrO 2 catalyst that had enhanced Cu dispersion. [4] Silica-supported copperc atalysts have excellent performance and have widely been used in hydrogenation reactions because of their excellent performance.…”

Insight into the Correlation between Cu Species Evolution and Ethanol Selectivity in the Direct Ethanol Synthesis from CO Hydrogenation

“…Despite that Al 2 O 3 support has been used for widespread applications, the relatively high quantity of acid sites on Al 2 O 3 surface may catalyze unwanted isomerization or oligomerization reactions according to many studies ,,,. Therefore, in the present study, an inert SiO 2 support with a large surface was considered as a suitable choice ,…”

“…It is generally thought that Cu dispersion and/or the distribution of Cu 0 and Cu + species have great influence on the product selectivity during the hydrogenation process over Cu‐based catalysts . Tuning catalyst preparation parameters (e. g. promoters, Cu loading, calcination temperature) of Cu‐based catalysts is really efficient to modify Cu dispersion and Cu + /(Cu 0 +Cu + ) value. According to the previous literatures, it is plausible that both more dispersed Cu species and higher Cu + /(Cu 0 +Cu + ) value are effective to improve the product selectivity.…”

“…In heterogeneous catalysis, metals or metal oxides are traditionally dispersed as nanoscale particles on a support with a large surface to maximize the number of exposed active sites . As reported, copper species are much easier to be highly dispersed on Al 2 O 3 or SiO 2 support with large surface in comparison to the TiO 2 support with a small surface. Despite that Al 2 O 3 support has been used for widespread applications, the relatively high quantity of acid sites on Al 2 O 3 surface may catalyze unwanted isomerization or oligomerization reactions according to many studies ,,,.…”