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Promoted ceria catalysts for alkyne semi-hydrogenation.
- Source :
-
Journal of Catalysis . Apr2015, Vol. 324, p69-78. 10p. - Publication Year :
- 2015
-
Abstract
- CeO 2 is a highly selective catalyst for the partial hydrogenation of alkynes. However, due to its limited H 2 splitting ability, a high operating temperature is required for the reaction, hampering the practical exploitation of this abundant oxide. In this work, we demonstrate that gallium promotes the activity of CeO 2 for the semi-hydrogenation of acetylene and methylacetylene, enabling a reduction of the operating temperature to 373 K, while maintaining an outstanding ethylene and propylene selectivity (80–97%), even in the presence of excess alkene in the feed. Oligomers comprised the main secondary product, while the selectivity to the corresponding alkane did not exceed 2%. The characterization of mixed Ce-Ga oxides reveals that the progressive incorporation of gallium into the ceria structure, forming a solid solution, boosts the oxygen storage capacity and the reducibility of the material. This is ascribed to the facilitated H 2 activation on the Ga-promoted samples, as confirmed by in situ infrared spectroscopy and density functional theory simulations. The interplay between the advantage brought by the decreased barrier for H 2 cleavage and the disadvantage due to the increased number of oxygen vacancies governs the reactivity of the CeGaO x catalysts in alkyne hydrogenation. The composition in the optimal catalyst, containing a molar Ce:Ga ratio of 95:5, was extrapolated to other trivalent cations. Indium incorporated in the ceria lattice favored the low-temperature H 2 activation and led to an activity enhancement that surpassed that of gallium. However, aluminum did not form a solid solution with ceria and caused no effect. This work comprises the first application of promoted cerias in hydrogenation catalysis and may prompt further developments in olefin purification. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00219517
- Volume :
- 324
- Database :
- Academic Search Index
- Journal :
- Journal of Catalysis
- Publication Type :
- Academic Journal
- Accession number :
- 101499516
- Full Text :
- https://doi.org/10.1016/j.jcat.2015.01.020