TiO2 polymorph dependent SMSI effect in Co-Ru/TiO2 catalysts and its relevance to Fischer-Tropsch synthesis
| Autor: | Francine Bertella, Patricia Concepción, Agustín Martínez |
|---|---|
| Přispěvatelé: | Ministerio de Economía y Competitividad (España) |
| Rok vydání: | 2017 |
| Předmět: |
Anatase
Cobalt catalyst 010405 organic chemistry Chemistry Inorganic chemistry chemistry.chemical_element Fischer–Tropsch process General Chemistry Thermal treatment Fischer-Tropsch synthesis 010402 general chemistry 01 natural sciences Catalysis 0104 chemical sciences Rutile Physisorption Chemisorption Cobalt TiO2 polymorph Syngas SMSI effect |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Popis: | Pure anatase and rutile TiO samples were synthesized by thermal treatment of reverse microemulsions and applied as supports for preparing Ru-promoted Co catalysts (0.5 wt% Ru, 10 wt% Co). The catalysts were characterized by ICP-OES, XRD, Raman spectroscopy, N physisorption, H-TPR, electron microscopy (FESEM, HAADF-STEM), H chemisorption, XPS, and in situ IR-CO after H reduction and reaction with syngas, and their catalytic performance for Fischer-Tropsch synthesis (FTS) studied at industrial conditions (220 °C, 2.0 MPa, H/CO = 2). The two catalysts exhibited comparable mean Co particle sizes (5–6 nm) as well as high and alike degrees of cobalt reduction (ca. 90%). The SMSI decoration effect arising during H reduction was much more pronounced for the anatase-supported catalyst resulting in lower cobalt-time-yield (CTY) compared to that supported on TiO-rutile. In situ IR-CO under syngas conversion conditions showed equivalent cobalt surface reconstruction and nature of the surface Co sites for both catalysts in their working state, and revealed a partial reversibility of the SMSI effect during FTS by which a significant fraction of the decorated Co centers in the anatase-based catalyst was uncovered and became available for reaction. The implication of this effect on TOFs is discussed. The C selectivity was higher for the rutile-based catalyst, although a clear impact of the SMSI effect on selectivities was not inferred from our results. Financial support by the MINECO of Spain through the Severo Ochoa project (SEV 2012-0267) is gratefully ackonowledged. The authors also thank the Microscopy Service of the Universitat Politècnica de València for its assistance in microscopy characterization. F. Bertella (Science without Frontiers – Process no. 13705/13-0) thanks CAPES for a predoctoral fellowship. |
| Databáze: | OpenAIRE |
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