Following the structure of copper-zinc-alumina across the pressure gap in carbon dioxide hydrogenation

Copper-zinc-alumina catalysts are used industrially for methanol synthesis from feedstock containing carbon monoxide and carbon dioxide. The high performance of the catalyst stems from synergies that develop between its components. This important catalytic system has been investigated with a myriad of approaches, however, no comprehensive agreement on the fundamental source of its high activity has been reached. One potential source of disagreement is the considerable variation in pressure used in studies to understand a process that is performed industrially at pressures above 20 bar. Here, by systematically studying the catalyst state during temperature-programmed reduction and under carbon dioxide hydrogenation with in situ and operando X-ray absorption spectroscopy over four orders of magnitude in pressure, we show how the state and evolution of the catalyst is defined by its environment. The structure of the catalyst shows a strong pressure dependence, especially below 1 bar. As pressure gaps are a general problem in catalysis, these observations have wide-ranging ramifications.

Automated summary

Copper-zinc-alumina catalysts are used in the industrial production of methanol from gases like carbon monoxide and carbon dioxide, with high performance due to synergies between its components. Research has shown that the state and evolution of the catalyst are significantly influenced by its environment, especially with strong pressure dependence observed at pressures below 1 bar. These findings have broad implications for catalysis due to the general problem of pressure gaps in such processes.