Kinetic mechanism of CO oxidation on gold catalyst supported on TiSBA-15 previously treated in a hydrogen atmosphere
Por:
Che-Galicia G., Ruíz-Santoyo V., Zanella R., Mendoza-González N.Y., Ruiz-López I.I., Sampieri A.
Publicada:
1 feb 2021
Resumen:
The CO oxidation by supported gold catalysts on TiSBA-15 was
investigated experimentally as well as via construction of a kinetic
model. Functionalization of the siliceous mesoporous SBA-15 with
titanium (IV) isopropoxide (Si/Ti: 20, 40 and 80 M ratios) was carried
out to prepare gold mesoporous catalysts with 2.5-2.9 Au wt.% through
the deposition-precipitation method assisted by urea. The samples were
characterized by X-ray diffraction, N-2 adsorption-desorption and TEM.
The gold amount was determined by chemical analysis (ICP-OES). Before
the CO oxidation, the samples were pretreated in air or H-2 atmosphere
at 300, 400 or 500 degrees C. The functionalization of SBA-15 with Ti
contributes to obtaining Au-0 nanoparticle sizes lower than 4 nm. Both
the H-2 atmosphere for reducing Au species and Si/Ti molar ratio on the
SBA-15 were crucial for increasing the catalytic activity. The catalytic
evaluation showed that the highest CO conversion is achieved when the
SBA-15 is enriched with a molar ratio of Si/Ti = 20 (Au/TiSBA20).
Kinetic experiments over Au/TiSBA20 catalyst were then used to construct
a series of kinetic models based on distinct mechanisms following a
Langmuir-HinshelwoodHougen-Watson type. Statistical analysis addressing
the physical meaning of the kinetic parameters allowed to elucidate two
dual-site surface reactions with the adsorption of COx and O-2 on Au-0
nanoparticles (NPs) and in the periphery of the Au-0 NPs with the
support, respectively, as a dominant mechanism. The estimated CO, CO2
and O-2 adsorption enthalpies amounted to -30, -39 and -13 kJ/mol,
respectively, while the activation energies varied from 78.8 to 81.7
kJ/mol.
Filiaciones:
Che-Galicia G.:
Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Av. San Claudio s/n, Col. San Manuel, Ciudad Universitaria 72570, Puebla, Mexico
Ruíz-Santoyo V.:
Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Av. San Claudio s/n, Col. San Manuel, Ciudad Universitaria 72570, Puebla, Mexico
Universidad de Guadalajara, Centro Universitario de los Altos, Departamento de Ingenierías, Laboratorio de Nanocatálisis, carretera a Yahualica, Km. 7.5, Tepatitlán de Morelos, 47600, Mexico
Zanella R.:
Instituto de Ciencias Aplicadas y Tecnología, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Mexico City, 04510, Mexico
Mendoza-González N.Y.:
Plasma Processing Laboratory, Department of Chemical Engineering, McGill University, 3610 University Ct., Montréal, Québec H3A 2B2, Canada
Ruiz-López I.I.:
Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Av. San Claudio s/n, Col. San Manuel, Ciudad Universitaria 72570, Puebla, Mexico
Sampieri A.:
Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Av. San Claudio s/n, Col. San Manuel, Ciudad Universitaria 72570, Puebla, Mexico
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