Synthesis of Pt@MAF-6 as a Steric Effect Catalyst for Selective Hydrogenation of Cinnamaldehyde
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Synthesis of Pt@MAF‑6 as a Steric Effect Catalyst for Selective Hydrogenation of Cinnamaldehyde Kaizhen Xue1 · Xiaocheng Lan1 · Jinfu Wang1 · Tiefeng Wang1 Received: 20 January 2020 / Accepted: 6 April 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Pt@MAF-6 was designed as a highly selective catalyst for cinnamaldehyde hydrogenation. The aperture of Pt@MAF-6 acted to sterically confine cinnamaldehyde, and 94% selectivity to cinnamic alcohol was obtained at a high conversion of 95%. Steric confinement was inefficient in trans-2-pentenal hydrogenation, showing that encapsulating active sites within a commensurate porous support is important for a steric effect catalyst. Graphic Abstract
Keywords Steric effect · Unsaturated aldehyde · Metal-organic framework · Catalyst design · Selective hydrogenation
1 Introduction Metal-organic frameworks (MOFs) are widely investigated for many applications, such as gas/liquid storage and separation [1], chemical sensor [2], drug delivery [3] and heterogeneous catalysis [4–7]. In particular, MOFs that encapsulate metal nanoparticles (NPs) are excellent catalysts for heterogeneous reactions [4], where MOFs serve as supports and help prevent the agglomeration of metal NPs during catalytic reactions. In addition, the well-defined porous structure of a Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10562-020-03212-0) contains supplementary material, which is available to authorized users. * Tiefeng Wang [email protected] 1
Beijing Key Laboratory of Green Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
MOF can impart a steric effect to the catalyst, and control its selectivity to different molecules. For example, Zhang et al. [8] encapsulated Pt NPs inside UIO-66, and showed that it gave shape selective properties in olefin hydrogenation. Furthermore, being comprised of unsaturated metal ions and functional groups on the organic linkers, MOFs themselves can be co-catalysts that work together with the metal NPs. For example, Chen et al. [9] developed ultrafine PdAg alloy NPs (~ 1.5 nm) in MIL-101 as a cascade reaction catalyst, which gave good catalytic activity and selectivity in the synthesis of 2-(4-aminophenyl)-1H-benzimidazole due to MOF Lewis acidity and synergy with the PdAg NPs. Selective hydrogenation of unsaturated aldehydes to unsaturated alcohols is an important process in the chemical industry [10–15]. It is challenging to get a high selectivity to unsaturated alcohols because the hydrogenation of C = C is thermodynamically more favorable than that of C = O [16]. Several strategies have been used to design highly selective catalysts for the hydrogenation of unsaturated alcohols,
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including using the electronic effect [17–23], synergistic effect [24, 25], and steric effect [26–28]. In particular, the steric effect can be used to significantly enhance C = O hydrogenation selectivity. T
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