Influence of the acid sites density in the acetone transformation over bifunctional Pt/H[Ga]ZSM5 catalysts

• Published in: Microporous and mesoporous materials Vol. 102; no. 1; pp. 86 - 94
• Main Authors: Mediavilla, Marta, Melo, Luis, Díaz, Yraida, Brito, Joaquín L., Albornoz, Alberto, Solano, Roger
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 04-05-2007; Elsevier
• Subjects: Acetone transformation; Bifunctional catalysts; Catalysis; Chemistry; Colloidal state and disperse state; Exact sciences and technology; Gallosilicates; General and physical chemistry; Ion-exchange; MIBK; Porous materials; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; XPS; Zeolites: preparations and properties; Bifunctional catalysts; MIBK; Gallosilicates; Acetone transformation; XPS; Bifunctional catalyst; Acidic site; X ray; Zeolite; Ketone; Density; Molecular sieve; Photoelectron spectrometry; Acetone
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2006.12.017

The purpose of this work is to elucidate the effect of acid sites density on the catalytic behaviour of a series of bifunctional catalysts prepared by supporting platinum (about 1.00
wt.%) on MFI-type gallosilicates (H[Ga]/ZSM5 with Si/Ga atomic ratio
=
16, 46 and 145). The XPS characterization studies of the bifunctional catalysts allowed to detect the presence of framework as well as extraframework gallium species for the catalyst with highest density of acid sites (Si/Ga
=
16), while only framework Ga species could be detected for catalysts with lower acid site density. It was also verified in all the bifunctional catalysts the presence of three types of metal sites: Pt (0), Pt–O
ads and PtO species. The results obtained in the synthesis of MIBK from acetone with the different bifunctional solids, indicate that as the density of the acid sites increases, the solids start to behave solely as acid catalysts. This phenomenon is probably related to the presence of extraframework gallium species in the catalyst with higher surface acidity, capable to interact with the platinum species and thus provoking the passivation of the metallic phase, while in the solids with lower surface acidity it seems to exist a better balance between the acidic–metallic functionalities.