【摘要】 利用Pt（Ⅳ）和Fe（Ⅱ）前驱体间的还原电势差引发的氧化还原反应合成了平均颗粒尺寸约为100 nm的一系列活性炭负载型Pt/Fe₃O₄催化剂.Fe₃O₄纳米颗粒能够有效防止所合成催化剂中Pt纳米颗粒的团聚并促进其在催化剂表面分散,从而暴露出更多的Pt活性位点,利于吸附和活化反应介质.XPS分析表明,在负载型Pt/Fe₃O₄催化剂中,通过Pt与Fe间的电子转移,Pt纳米颗粒表面处于富电子状态,使得反应物中的C=O双键以竖式方式吸附于Pt活性位上,进而促进了C=O双键的吸附和活化.实验结果表明,在肉桂醛转移加氢反应过程中,Pt含量为2.46wt%的负载型Pt/Fe₃O₄催化剂展现了最佳的催化活性:在以异丙醇为氢源,120℃,6 h反应条件下,目标产物肉桂醇的选择性达到94.8%.此外,该催化剂因其天然的磁特性,可以简单便捷地从反应体系中分离,且展现了良好的循环稳定性.更多还原

【Abstract】 A variety of spherical and structured activated charcoal supported Pt/Fe₃ O₄ composites with an average particle size of ～100 nm have been synthesized by a self-assembly method using the difference of reduction potential between Pt（Ⅳ） and Fe（Ⅱ） precursors as driving force. The formed Fe₃ O₄ nanoparticles（NPs） effectively prevent the aggregation of Pt nanocrystallites and promote the dispersion of Pt NPs on the surface of catalyst, which will be favorable for the exposure of Pt active sites for high-efficient adsorption and contact of substrate and hydrogen donor. The electron-enrichment state of Pt NPs donated by Fe₃ O₄ nanocrystallites is corroborated by XPS measurement, which is responsible for promoting and activating the terminal C=O bond of adsorbed substrate via a vertical configuration. The experimental results show that the activated charcoal supported Pt/Fe₃ O₄ catalyst exhibits94.8% selectivity towards cinnamyl alcohol by the transfer hydrogenation of cinnamaldehyde with Pt loading of 2.46% under the optimum conditions of 120 ℃ for 6 h, and 2-propanol as a hydrogen donor. Additionally, the present study demonstrates that a high-efficient and recyclable catalyst can be rapidly separated from the mixture due to its natural magnetism upon the application of magnetic field.更多还原