The effect of support properties in the preparation of Pd size-controlled catalysts by 鈥渨ater-in-oil鈥?microemulsion method

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• 作者：R. Kosydar ; M. Gó ; ral ; J. Gurgul ; A. Drelinkiewicz ; ^{ncdrelin@cyf-kr.edu.pl}
• 关键词：Water-in-oil microemulsion ; Particle aggregation ; Palladium ; Hydrogenation
• 刊名：Catalysis Communications
• 出版年：2012
• 期刊代码：12_15667367
• 类别：ce
• 出版时间：10 May, 2012
• 卷：22
• 期：Complete
• 页码：58-67
• 文件大小：1878 K

摘要

The palladium particles pre-formed by 鈥渨ater-in-oil鈥?microemulsion method were deposited onto carbon, silica and cellulose supports which differed in hydrophobic and textural properties. Microemulsions with anionic bis(2-ethylhexyl)sulfosuccinate (AOT) and non-ionic polyoxyethylene(7-8)octylphenyl ether (Triton-X 114) surfactants were used. Palladium particles of size with narrow range but various average sizes (ca. 8-9 and ca. 4 nm) were obtained using hydrazine hydrate or NaH₂PO₂ as reducing agents. The results obtained by a number of techniques (XPS, XRD, SEM, TEM) showed that porosity of support and polarity of its surface determined the migration of Pd particles inside the pore structure as well as their aggregation in the final catalysts. Increased polarity of silica surface due to pre-treatment with water produced the most extensively aggregated particles. Pre-treatment of silica with non-polar cyclohexane, the solvent of bulk microemulsion, exhibited a very advantageous role because both processes migration and aggregation of primary Pd particles were almost completely inhibited. In the obtained 1%Pd/SiO₂ catalyst no aggregated particles appeared and it exhibited very high activity in liquid phase hydrogenation of styrene.