Mesostructured silicas as supports for palladium-catalyzed hydrogenation of phenyl acetylene and 1-phenyl-1-hexyne to alkenes

• Published in: Journal of molecular catalysis. A, Chemical Vol. 247; no. 1; pp. 145 - 152
• Main Authors: Marín-Astorga, Norman, Pecchi, Gina, Pinnavaia, Thomas J., Alvez-Manoli, Gabriela, Reyes, Patricio
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 16-03-2006; Elsevier
• Subjects: Catalysis; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; HMS; MCM-41; Mesostructured; MSU-X; Porous materials; Silica; Stereo-selectivity; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Mesostructured; Pd; Stereo-selectivity; MCM-41; Silica; MSU-X; HMS; Catalytic reaction; Hydrocarbon; Acetylenic compound; Support; Transition metal; Palladium; Selectivity; Porous material; Hydrogenation; Mesoporosity; Stereoselectivity; Heterogeneous catalysis; Alkene; HMS: MCM-41; Platinoid; Ethylenic compound
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2005.11.031

The stereoselective hydrogenation of phenyl acetylene and 1-phenyl-hexyne at 298
K and atmospheric pressure of H
2 over HMS, MSU-X, and MCM-41 supported Pd catalysts has been studied. The reactions were found to be zero order concerning the phenyl acetylene and 1-phenyl-1-hexyne concentration. The catalytic behaviour suggests an important effect produced by the differences in the characteristics of the supports. Thus, the 1%Pd/HMS catalyst was the most active compared to 1%Pd/MSU-X and 1%Pd/MCM-41 catalysts, which was attributed to the presence of interconnected channels which can increase the activity in a higher extent compared to straight channels observed in the others support. All catalysts displayed high selectivity to styrene and
cis-1-phenyl-1-hexyne compounds.
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The stereoselective hydrogenation of phenyl acetylene and 1-phenyl-1-hexyne at 298
K and atmospheric pressure of H
2 over Pd catalysts supported on mesostructured silica was studied. The catalysts were prepared by the impregnation of HMS and MSU-X silicas with 3-D wormhole framework structures and MCM-41 silica with a 1-D hexagonal framework using a toluene solution of Pd(acac)
2 to obtain a metal content close to 1
wt.%. All the supports were characterised by nitrogen adsorption–desorption isotherms at 77
K and XRD. The catalysts were characterized by H
2 chemisorption and TEM measurements. The reactions were found to be zero order with respect to the phenyl acetylene and 1-phenyl-1-hexyne concentration. Each catalyst presented a different catalytic performance. The 1%Pd/HMS catalyst was the most active in comparison with the 1%Pd/MSU-X and 1%Pd/MCM-41 catalysts. This superior performance in the case of the HMS support was attributed to the presence of interconnected framework channels and textural mesoporosity that can increase the accessibility of the Pd centers to a greater extent than the more monolithic MSU-X and MCM-41 supports. All catalysts displayed high selectivity to styrene and
cis-1-phenyl-1-hexene compounds.