Mesoporous Alumina and Aluminosilica with Pd and Pt Nanoparticles: Structure and Catalytic Properties

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• 作者：Lyudmila M. Bronstein ; Dmitri M. Chernyshov ; Robert Karlinsey ; Josef W. Zwanziger ; Valentina G. Matveeva ; Esther M. Sulman ; Galina N. Demidenko ; Hans-Peter Hentze ; and Markus Antonietti
• 刊名：Chemistry of Materials
• 出版年：2003
• 出版时间：July 1, 2003
• 年：2003
• 卷：15
• 期：13
• 页码：2623 - 2631
• 全文大小：315K
• 年卷期：v.15,no.13(July 1, 2003)
• ISSN：1520-5002

文摘

Cationic and anionic microgels based on sulfonated polystyrene and poly(ethylmethacryltetramethylammonium chloride) and containing Pd and Pt nanoparticles were used astemplates along with polystyrene-block-poly(ethylene oxide) block copolymers for castingnanoporous alumina and aluminosilica with nanoparticles. The Pt-nanoparticle-containingaluminosilica consists of interpenetrating pores and Pt particles of 7 nm in diameter (byX-ray diffraction) located in the interpore channels. Pd nanoparticles are smaller and partiallyblock the pore entrances of Pd-nanoparticle-containing aluminosilica, decreasing the porosity.Metal-particle-containing aluminas templated both over cationic and anionic microgels consistof an interpenetrating pore system and alumina nanowires (2-3 nm in diameter and about40 nm in length) along with Pd or Pt nanoparticles. This combination creates highermesoporosity than for aluminosilicas. The ²⁷Al MAS NMR spectra of metal-nanoparticle-containing alumina show two distinct sites at 0 and 65 ppm independently of metal ormicrogel types, indicating octahedral and tetrahedral coordination, respectively; theoctahedral species strongly prevail. The aluminum spectra of all aluminosilica samples showa more complicated picture, with octahedral and tetrahedral aluminum along with probablepentacoordinated species. The catalytic properties of Pd(Pt)-nanoparticle-containing aluminasand aluminosilicas were studied in partial hydrogenation of three amphiphilic acetylenealcohols having a different length of the hydrophobic tail. The aluminosilicas showed lowactivity and selectivity for all substrates, while Pd-particle-containing aluminas displayedhigh activity and selectivity, especially for acetylene alcohol with the longest aliphatic tail(dehydroisophytol, acetylene alcohol C₂₀).