(100e) Preconditioning Effects Upon Co-Containing Pt-Promoted and Unpromoted Fischer-Tropsch Catalysts

As part of a research program to create, prepare, and evaluate Fischer-Tropsch (FT) catalysts, active catalysts formed by atomic-layer deposition [ALD] of major components were demonstrated.  ALD-deposited Co on a silica support was more effective than a similar catalyst deposited upon a support of ALD-deposited Al₂O₃ on silica. The activities of Co on Al₂O₃ catalysts prepared by the Center for Applied Energy Research (CAER) were compared with those of these catalysts.  The addition of Pt, by either ALD or incipient wetness techniques, as a promoter of Co-containing catalyst has been shown to primarily affect the catalyst pre-conditioning step. CO conversion results were consistent with previously reported ¹ TPR-XANES/EXAFS experiments observing the nature of the chemical transformations occurring during the activation of cobalt-based FT catalysts in H₂.  Specifically, there exists a 2-step reduction process involving Co₃O₄ to CoO to Co⁰ transformations. The extent of catalyst preconditioning was strongly affected by the reduction temperature and the level of Pt deposition. A continuous-flow catalytic-bed unit was used for this FT study.  The gaseous feed consisted of either a 1:1 or 2:1 molar blend of H₂:CO, and the experiments were carried out at temperatures ranging from about 260°C to 300°C, pressures averaging 13.1 MPa (190 psia), a gas feed rate of about 15 mL/min, and a catalyst charge of 0.1 g.

1. G. Jacobs, Y. Ji, B.H. Davis, D.C. Cronauer, A.J. Kropf, C.L. Marshall, Applied Catalysis A, General  333 (2007),  177-191