Hydrogenation of Dimethyl Oxalate over Copper-Based Catalysts: Acid–Base Properties and Reaction Paths

Hydrogenation of dimethyl oxalate (DMO) is a potentially important process in C1 chemistry, which produces ethylene glycol (EG) around 473 K and ethanol with higher alcohols (propanol, butanol, etc.) around 553 K. However, the detailed inter-relationship of formation paths for these products has not yet been discussed properly. In this study, we found that the formation paths of higher alcohols from DMO were inhibited around 473 K. On the basis of these results, a two-reactor system with different reaction temperatures was suggested to obtain less of the higher alcohols and more ethanol. Besides, it is found that a higher density of basic sites in the catalyst favors the formation of higher alcohols. An aluminum dopant was applied to decrease the basic sites in the catalysts accompanied by an increment of ethanol selectivity. When the aluminum-doped catalysts were introduced into the two-reactor system, a further improvement in ethanol selectivity was achieved.