Calcination-modulated Cu redistribution in CuZr catalysts governs downstream ethylene glycol hydrogenolysis in dimethyl oxalate-to-ethanol conversion

Calcination-driven Cu exsolution from a CuZr precursor tunes the Cu-ZrO 2 interfacial environment. • Catalysts with the optimal interfacial environment achieve ethanol selectivity approaching 90%. • Kinetic analysis and in situ DRIFTS support a dehydration‑hydrogenation pathway at the Cu-ZrO 2 interface. • DFT reveals that Cu-ZrO 2 interface converts high-barrier concerted dehydration into a lower-barrier stepwise route. The selective hydrogenolysis of ethylene glycol (EG) to ethanol is a critical step in the dimethyl oxalate (DMO)-to-ethanol process, yet the catalytically relevant Cu environment for this transformation remains insufficiently understood. Here, we prepared a series of CuZr catalysts with distinct Cu-ZrO 2 interfacial structures through calcination-induced structural evolution. Structural characterization reveals that calcination progressively redistributes Cu species from a more bulk-associated state in ZrO 2 to surface-enriched Cu, and ultimately to segregated Cu-rich domains. Among the catalyst series, calcination at an intermediate temperature of 550 °C gave the best performance. Ethanol yield scaled with the accessible Cu surface area, and both exhibited a volcano-type dependence on calcination temperature, whereas the Cu-normalized TOF decreased monotonically. This discrepancy underscores that exposed Cu alone cannot account for the catalytic behavior, and suggests an important contribution from coupled Cu-ZrO 2 interfacial environments. Kinetic analysis and in situ DRIFTS support a pathway involving dehydration-related transformation of EG followed by hydrogenation of carbonyl-type intermediates. DFT results further suggest that, relative to pristine ZrO 2 , the Cu-ZrO 2 interface stabilizes dehydration related carbon-containing intermediates, thereby enabling a more accessible stepwise pathway for EG dehydration and facilitating the subsequent hydrogenation to ethanol. These findings provide an interface engineering strategy for designing Cu-based catalysts in the DMO-to-ethanol process and related polyol hydrogenolysis reactions. Download: Download high-res image (129KB) Download: Download full-size image