Infrared Spectroscopic Study of the Carbon Dioxide Adsorption on the Surface of Cerium-Gallium Mixed Oxides

G. FINOS; S. COLLINS; G. BLANCO; E. DEL RÍO; J. CIES; S. BERNAL; A. BONIVARDI

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ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2011 vol. 180 p. 9 - 18

0920-5861

In order to modified the acid?base properties of pure cerium dioxide, a series of ceria-based oxides dopedwith gallium(III) cations (from 5 to 50% mol/mol of Ga) was prepared by co-precipitation in basic aqueoussolution followed by calcination at 773 K. N2 physisorption at 77 K showed that mesoporous materialswith surface areas between 75 and 104 m2/g were obtained. Ga(III) cations were incorporated into theceria crystal structure up to a concentration close to 20?25% mol/mol of Ga, as revealed by powder X-raydiffraction analysis. Surface basicity was investigated using CO2 chemisorption by mass spectrometry andin situ infrared spectroscopy. A progressive decrease in the surface basicity in the series of ceria?galliamaterials was observed as the Ga content increases. Different carbonate and bicarbonate surface specieswere identified through their vibrational infrared modes. A remarkable decrease in the surface stabilityof carbonate species, particularly of the polydentate carbonate groups, was detected, which is correlatedto the incorporation of gallium(III) into the ceria lattice.