Spectroscopic Reactor for <i>Operando</i> Investigations Made by Additive Manufacturing for High‐Pressure Catalysis Applications

Knowledge‐based catalyst design requires the identification of the active structure during reaction, i.e., by operando spectroscopy, and at different conversion levels. However, for reactions that run at elevated pressure, such as methanol, Fischer–Tropsch, or ammonia synthesis, obtaining spectroscopic data at realistic conditions remains a major challenge. In particular, standard operando setups often fail to replicate the high‐pressure, high‐conversion regimes relevant to industrial processes. This requires specially designed reactors, and here, how additive manufacturing enables the development of spectroscopic reactors for operando studies of catalysts under high‐pressure conditions at different conversion levels up to equilibrium is reported. The reactor has two consecutive zones with independent temperature control and individual catalyst loading. An X‐ray‐transparent window in the latter zone allows for spatially resolved spectroscopic monitoring of the catalyst structure. A mobile setup is constructed for operation at a synchrotron source, and the functionality of the reactor is demonstrated in an operando X‐ray absorption spectroscopy study using a Cu/ZnO/ZrO 2 catalyst during CO 2 hydrogenation to methanol. The dual‐zone design enabled simulation of an end‐of‐catalyst‐bed environment, including condensation, which is highly critical for industrial relevance yet difficult to realize in conventional operando experiments.