Catalysts microstructure

Parallel chemical studies and correlations with the catalyst microstructure... 

Correlations of the catalyst microstructure with catalytic activity and selectivity... 

Erom HRTEM studies, it is proposed that the majority of the bismuth molybdate phases can be derived from the fluorite structure, in which both the cation and anion vacancies can be accommodated within the fluorite framework (Buttrey et al 1987). Several industrial processes containing multicomponent bismuth molybdates may suffer loss of Mo oxides by volatilization under operating conditions, resulting in the loss of catalytic activity. Monitoring the catalyst microstructure using EM is therefore crucial to ensuring the continuity of these catalytic processes. 

Figure 1.5 Rhodium honeycomb catalyst microstructure device. The microchannels have been manufactured by wire erosion.

The catalyst has been designed as given in Ref The proposed process of knowledge extraction consists in planning HTE experiments in a way allowing for the discrimination of the models of catalytic reactions, determination of the kinetic constants, and relating them to the catalyst microstructure. The proposed forward modeling is realized by the application of the... 

Only the final product of the process (19.10), that is, molecular hydrogen (H2, HD, and D2), can be detected by online mass spectrometry. However, the catalyst microstructure may be reconstructed by the computer simulation, since the gas evolved remembers the surrounding hydrogen atoms in the environs Had and Dad atoms serve as peculiar markers of reactions (19.11) and (19.12) and thereby define on which site—either anodic or cathodic—they appear. The location of reactions (19.11) and (19.12) at specific site ensembles seems to be probable, taking into account a heterogeneity (structural, chemical, and energetic) of the real catalyst surface. This could be reconstructed from the H2, HD, and D2 distribution in the gas. 

Cheng X, Chen L, Peng C, Chen Z, Zhang Y, Fan Q. Catalyst microstructure examination of PEMFC membrane electrode assemblies vs. time. J Electrochem Soc 2004 151 A48-52. 

Results were largely confirmed in a later work by Baradwaj and Schmidth, who found that the reaction was highly sensitive to the catalyst microstructure, as activation and differences in performance were observed on catalysts with different support materials. 

Keywords Pt/(Ce02-Ti02) catalysts, microstructure, oxidation of CO... 

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