Open AccessFollowing Cu Microstructure Evolution in CuZnO/Al 2 O 3 (−Cs) Catalysts During Activation in H 2 using in situ XRD and XRD‐CT
Author(s) -
Farmer Daniela M.,
Jacques Simon D. M.,
Waller David,
Boullosa Eiras Sara,
Roy Kanak,
Held Georg,
Sankar Gopinathan,
Beale Andrew M.
Publication year - 2023
Publication title -
chemistry ‐ methods
Language(s) - English
Resource type - Journals
ISSN - 2628-9725
DOI - 10.1002/cmtd.202200015
Subject(s) - crystallite , materials science , microstructure , sintering , catalysis , stacking fault , copper , crystallography , methanol , stacking , analytical chemistry (journal) , dislocation , metallurgy , chemistry , composite material , chromatography , biochemistry , organic chemistry
Understanding how the microstructure of the active Cu 0 component in the commercially applicable Cu/ZnO/Al 2 O 3 (−Cs 2 O) low‐temperature water‐gas shift catalyst evolves under various H 2 partial pressures in the presence/absence of a Cs promoter during thermal activation has been investigated. Time‐resolved XRD and spatially‐resolved XRD‐CT data were measured as a function of H 2 concentration along a packed bed reactor to elucidate the importance of the zincite support and the effect of the promoter on Cu sintering mechanisms, dislocation character and stacking fault probability. The rate of Cu reduction showed a dependency on [Cs], [H 2 ] and bed height; lower [Cs] and higher [H 2 ] led to a greater rate of metallic copper nanoparticle formation. A deeper analysis of the XRD line profiles allowed for determining a greater edge character to the dislocations and subsequent stacking fault probability was also observed to depend on higher [H 2 ], smaller Cu 0 (and ZnO) crystallite sizes, increased [ZnO] (30 wt.%, sCZA) and lower temperature. The intrinsic activity of Cu/ZnO/Al 2 O 3 methanol synthesis catalysts has been intimately linked to the anisotropic behaviour of copper, and thus the presence of lattice defects; to the best knowledge of the authors, this study is the first instance in which this type of analysis has been applied to LT‐WGS catalysts.