δ -Alumina supported cobalt catalysts promoted by ruthenium for Fischer-Tropsch synthesis

Kungurova, Olga A.; Cherepanova, Svetlana V.; Saraev, Andrey A.; Kaichev, Vasily V.; Shtertser, Natalia V.; Chermashentseva, Galina K.; Gerasimov, Еvgeny Yu.; Paukshtis, Еvgeny A.; Vodyankina, Olga V.; Khassin, Alexander A.; Minyukova, Tatyana P.; Abou-Jaoudé, Georges

δ -Alumina supported cobalt catalysts promoted by ruthenium for Fischer-Tropsch synthesis

Kungurova, Olga A., Cherepanova, Svetlana V., Saraev, Andrey A., Kaichev, Vasily V., Shtertser, Natalia V., Chermashentseva, Galina K., Gerasimov, Еvgeny Yu., Paukshtis, Еvgeny A., Vodyankina, Olga V., Khassin, Alexander A., Minyukova, Tatyana P., Abou-Jaoudé, Georges

Дата публикации: 2017

Дата публикации в реестре: 2020-03-03T19:07:11Z

Аннотация:

The paper presents the low-temperature nitrogen adsorption, TG, XRD, IR spectroscopy, XPS, TEM and SEM data for ruthenium promoted (0.2–1 wt.%) Сo-δAl2O3 catalysts and characteristics of the catalysts in Fischer-Tropsch synthesis after their activation under the conditions ensuring the reduction of comparable fractions of metallic cobalt. It was shown that cobalt in oxide precursors is a component of the spinel-like Со3-xAlxO4 phase containing the impurity anions СО32−, NO3−, ОН−, and NO in promoted samples, which belong to the thermolysis product of the Ru precursor. Average sizes of Со3-xAlxO4 crystallites are in a range of 5–10 nm. As ruthenium content in the catalyst increases upon reduction, the temperature of metallic phase formation decreases substantially (by more than 150 °C). After the reduction, selectivity of promoted catalysts for α-olefins and high-molecular hydrocarbons was higher in comparison with unpromoted catalysts, without a noticeable decrease in catalytic activity. Therewith, in 0.5–1.0 wt.% catalysts, a part of ruthenium forms individual ultradispersed metallic particles ca. 1 nm in size that are located on the surface of oxide support and are not active in Fischer-Tropsch synthesis. The oxide layer decorating the surface of metallic cobalt particles is also strongly enriched with ruthenium. In the 0.2 wt.% catalyst, the major part of ruthenium resides in metallic cobalt particles. Although the ruthenium-cobalt alloy segregates with enrichment of the surface with cobalt, the presence of ruthenium in the metallic particles and probably in the decorating oxide layer exerts a considerable effect on selectivity of the catalysts.

Ключевые слова:
алюминиевые катализаторы, Фишера-Тропша синтез, кобальтовые сплавы

Тип: статьи в журналах

Источник: Applied catalysis A: General. 2017. Vol. 539. P. 48-58