Fei Tan, Kong; Xu, Jing; Chang, Jie; Borgna, Armando; Saeys, Mark

Journal of Catalysis (2010), 274(2), 121-129 CODEN: JCTLA5; ISSN: 0021-9517. English.

The deactivation of a 20% Co/.gamma.-Al2O3 catalyst during Fischer-Tropsch Synthesis (FTS) at 240.degree.C, 20 bar, and a H2:CO ratio of 2 was studied in a fixed-bed micro-reactor. The CO conversion had reduced by 30% after 200 h, and both carbidic and polyarom. carbon species could be detected on the catalyst using a combination of Temp.-Programmed Hydrogenation (TPH), XPS and High Resoln. TEM (HRTEM). Using D. Functional Theory (DFT), the relative stability of different types of deposited carbon on the Co catalyst was evaluated. Extended layers of graphene were the most stable form, followed by a p4g surface carbide phase initiating from the step edges. Both are more stable than surface CH2 groups by 99 and 79 kJ/mol. The calculated C 1s core-level binding energies of 284.5 and 283.4 eV further support the presence of polyarom. carbon and of a surface carbide.