Promoted ceria catalysts for alkyne semi-hydrogenation

GIANVITO VILÉ; PATRICK DÄHLER; JULIA VECCHIETTI; MIGUEL BALTANÁS; SEBASTIÁN COLLINS; MÓNICA CALATAYUD; ADRIAN BONIVARDI; JAVIER PÉREZ-RAMÍREZ

JOURNAL OF CATALYSIS

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2015 vol. 324 p. 69 - 78

0021-9517

CeO2 is a highly selective catalyst for the partial hydrogenation of alkynes. However, due to its limited H2 splitting ability, ceria requires a high operating temperature, hampering the practical exploitation of this abundant oxide. Here, we demonstrate the application of gallium as a highly effective dopant of CeO2 for acetylene hydrogenation, enabling operating temperatures down to 373 K, while maintaining an outstanding ethylene selectivity (80-95%) and stable behavior. The characterization of mixed Ce-Ga oxides with variable gallium content reveals that the progressive incorporation of the trivalent metal into the structure of ceria boosts the oxygen storage capacity and the reducibility of the material. This is ascribed to the facilitated H2 activation on the Ga-doped samples, as confirmed by in situ infrared spectroscopy and Density Functional Theory. Hydrogenation tests show that the interplay between the advantage brought by the decreased barrier for H2 cleavage and the disadvantage due to the increased number of oxygen vacancies govern the performance of the gallium-doped catalysts. Accordingly, tuning the gallium content in the Ce(Ga)Ox solid solution is crucial to attain an optimal catalyst at a molar Ce:Ga = 95:5. The catalyst design achieved in this work brings the purification of light olefins over promoted ceria closer to practical realization.