Drastic Events and Gradual Change Define the Structure of an Active Copper‐Zinc‐Alumina Catalyst for Methanol Synthesis

Abstract

The copper-zinc-alumina (CZA) catalyst is one of the most important catalysts. Nevertheless, understanding of the complex CZA structure is still limited and hampers further optimization. Critical to the production of a highly active and stable catalyst are optimal start-up procedures in hydrogen. Here, by employing operando X-ray absorption spectroscopy and X-ray diffraction, we follow how the industrial CZA precursor evolves into the working catalyst. Two major events in the activation drastically alter the copper-and zinc-containing components in the CZA catalyst and define the final working catalyst structure: the reduction of the starting copper(II) oxide, and the ripening and reoxidation of zinc oxide upon the switch to catalytic conditions. These drastic events are also accompanied by other gradual, structural changes. Understanding what happens during these events is key to develop tailored start-up protocols that are aimed at maximal longevity and activity of the catalysts.

Engineering nanoscale H supply chain to accelerate methanol synthesis on ZnZrOx

“…XANES and EXAFS analyses after the reaction reveal that there are no substantial changes in the chemical state of either Zn or Zr in Pd/ CNT + ZnZrO x , validating the superior stability of Pd/CNT + ZnZrO x (Supplementary Figs. [10][11]. Both catalysts were additionally tested at a higher GHSV (80,000 cm 3 STP g cat.…”

“…Carbon Recycling International established the world's first large-scale CO 2 -to-methanol plant using Cu/ZnO/Al 2 O 3 , a classical catalyst originally developed and optimized for syngas-to-methanol conversion 6 . Numerous efforts are still being undertaken to elucidate the active site and optimize catalyst activity [7][8][9][10] . Nevertheless, one of the critical limitations of Cu/ZnO/ Al 2 O 3 is deactivation due to the unsatisfactory stability of the catalyst under exposure to heat and moisture, hampering long-term process operation [11][12][13][14] .…”

Hydrogen Interaction with Oxide Supports in the Presence and Absence of Platinum

“…In a catalytic process that also contains oxidant as a catalytic reagent besides hydrogen, this oxidant can counteract the observed reduction processes, and therefore, the reduction may not proceed to such a deep level. , Moreover, the counterplay of hydrogen reduction and the following oxidation can induce dynamics at the platinum metal oxide interface, which would not occur in a purely reducing environment …”

“…In the latter case, the metal oxide support is not a mere active site carrier but adds essential functions by so-called metal–support interactions . Such catalysts are often exposed to hydrogen atmospheres during the activation procedure to transform the catalyst precursor into an active state, e.g., by reduction of the supported metal or to induce structural modifications, or during the actual catalytic operation in (de)­hydrogenation reactions. , Especially the use of oxides in catalyzed hydrogenation reactions is interesting. However, why some oxides act as better hydrogenation catalysts or supports than others is still poorly understood .…”

Controlling the Strong Metal‐Support Interaction Overlayer Structure in Pt/TiO2 Catalysts Prevents Particle Evaporation

“…Exploiting the restructuring of catalysts by targeted (pre)treatment is a key concept of virtually all catalytic processes. [6,7,19] Either these treatments are applied as preforming step inside a reactor to get the catalyst into a selective and active state [20,21] or they can be applied in intervals during the catalytic process to regenerate the deactivated catalyst. [22] Supported noble metal NPs, due to scarcity and price of the materials, need to operate at their full potential.…”