Effect of boric oxide doping on the stability and activity of a Cu–SiO₂ catalyst for vapor-phase hydrogenation of dimethyl oxalate to ethylene glycol

• Published in: Journal of catalysis 2011-01, Vol.277 (1), p.54-63
• Main Authors: He, Zhe, Lin, Haiqiang, He, Ping, Yuan, Youzhu
• Format: Article
• Language: English
• Subjects: Acids; adsorption; boric acid; boron; carbon monoxide; Catalysis; Catalysts; catalytic activity; Chemistry; Copper; dispersions; electrons; esters; ethylene glycol; Exact sciences and technology; Fourier transform infrared spectroscopy; gelation; General and physical chemistry; Hydrogenation; nitrous oxide; Semiconductor doping; silica; Surface physical chemistry; surfaces; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; urea; vapors; X-ray diffraction
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2010.10.010

Stable and efficient B–Cu–SiO₂ catalysts for the hydrogenation of dimethyl oxalate (DMO) to ethylene glycol were prepared through urea-assisted gelation followed by postimpregnation with boric acid. Auger electron spectroscopy and CO adsorption by in situ Fourier transform infrared spectroscopy revealed that the Cu⁺ species on the catalyst surface increased together with an increase in the amount of boric oxide dopant. X-ray diffraction and N₂O chemisorption indicated that a suitable amount of boric oxide doping tended to improve copper dispersion and retard the growth of copper particles during DMO hydrogenation. Catalytic stability was greatly enhanced in the B–Cu–SiO₂ catalyst with an optimized Cu/B atomic ratio of 6.6, because of the formation and preservation of appropriate distributions of Cu⁺ and Cu⁰ species on the catalyst surfaces. The effect of boric oxide was attributed to its relatively high affinity for electrons, which tended to lower the reducibility of the Cu⁺ species.