Effect of cu content on Ce‐doping CuO/ZrO₂ catalysts for low‐temperature hydrogenation of dimethyl oxalate to ethanol

Abstract

In order to solve the Cu sintering in dimethyl oxalate (DMO) hydrogenation to ethanol, the reaction temperature should be kept at a low value, however, which is unable to show excellent catalytic performance. Herein, the reaction temperature decreased significantly from above 260 to 220°C over Ce‐doping Cu/ZrO2 catalyst, which retained high catalytic efficiency with little influence on the catalyst structure after 96 h on stream. Besides, the structure and performance were changed greatly by adjusting the Cu content. For example, the ethanol selectivity can reach 96.1% based on the 100% conversion of DMO over Ce‐doping Cu/ZrO2 catalysts with 40% content of Cu. Based on systematic characterization, the catalyst possessed higher exposed Cu surface area along with the proper amount of medium acidic sites, avoiding the strong ones that could bring about a series of by‐products. As a result, the formed synergistic effects between Cu sites and medium acidic sites provided the active sites with high efficiency for ethanol synthesis.

Comparative study on CuO–La2O3/ZrO2 catalysts prepared by amino acid complexing‐combustion in CO2 hydrogenation

“…The preparation procedure of CuO–La 2 O 3 /ZrO 2 catalysts was similar to that of the single‐pot citrate complex route or salicylic acid complex process 30–32 . The loading amount of Cu was 32 wt%, and the La content was kept at 1.5 wt%.…”

“…The preparation procedure of CuO-La 2 O 3 /ZrO 2 catalysts was similar to that of the single-pot citrate complex route or salicylic acid complex process. [30][31][32] The loading amount of Cu was 32 wt%, and the La content was kept at 1.5 wt%. It should be noted that the solvent employed in complexing process was water as an environmentally friendly solvent.…”

“…Generally speaking, ZrO 2 had various basic centers on its surface such as strongly basic surface O 2À ions, mediumstrength basic Zr 4+ -O 2À pairs and low-strength basic OH groups, which can effectively adsorb CO 2 and show desorption peaks at different temperatures. 32,44 In addition, the binding of La oxide with Cu and Zr species may affect the surface basicity. 45 CO 2 -TPD profiles of asobtained CuO-La 2 O 3 /ZrO 2 catalysts are shown in Figure 4a.…”