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Surface morphology of platinum catalysts
| Content Provider | Semantic Scholar |
|---|---|
| Author | Flytzani-Stephanopoulos, M. Wong, S. Schmidt, Lanny D. |
| Copyright Year | 1977 |
| Abstract | Surface morphologies of small (< 0.06 cm diameter) single crystal spheres of Pt and other transition metals are examined using scanning electron microscopy (SEM) following their use as catalysts in NH3, C3H8, and CO oxidation reactions and in NH3 decomposition at a total pressure of 1 atm. The stabilities of all regions of the stereographic triangle are examined from SEM micrographs and reflectance patterns, and relative areas of planes are estimated. Between one and five stable crystal planes are observed for these reactions, and the planes formed and their relative areas depend strongly on the reaction and reactant composition. Unstable planes break up into facets of these planes, but smooth curved regions and pits are observed under certain conditions. Dependences on time, temperature, sphere diameter, and flow velocity are examined for NH3 oxidation. It is found that the rate of facet formation is larger on small spheres and that the stable planes and their relative areas are influenced by both sphere diameter and flow velocity. Facet dimensions are 1 to 5 μm for all reactions under most conditions, and facet size increases slowly with reaction time. It is shown that metal transport by either surface diffusion or volatile oxide formation is possible in most cases and that minimum surface free energy considerations can account for unstable and metastable regions and faceting rates. Boundary layer influences on metal transport and the dependence of etching on sphere diameter and flow velocity are also considered. |
| Starting Page | 51 |
| Ending Page | 82 |
| Page Count | 32 |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/0021-9517(77)90239-1 |
| Alternate Webpage(s) | http://ase.tufts.edu/nano-cel/publications/surfaceMorphologyPlatinum.pdf |
| Alternate Webpage(s) | https://doi.org/10.1016/0021-9517%2877%2990239-1 |
| Volume Number | 49 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
