Improved Postsynthesis Strategy to Sn-Beta Zeolites as Lewis Acid Catalysts for the Ring-Opening Hydration of Epoxides

Tang, Bo; Dai, Weili; Wu, Guangjun; Guan, Naijia; Li, Landong; Hunger, Michael

doi:10.1021/cs500891s

Cited by 265 publications

(294 citation statements)

References 42 publications

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“…Epoxide ring-opening reactions on 1,2-epoxyalkanes were selected for catalysis, because they have been shown to take place within molecular sieves at relatively low temperatures (35)(36)(37). Such low-temperature probe reactions are particularly desirable because symmetrybreaking dispersive interactions with the catalyst surface are expected to be relatively large contributors to the transition state free energies compared with high-temperature scenarios.…”

Section: Resultsmentioning

confidence: 99%

Enantiomerically enriched, polycrystalline molecular sieves

Brand

Schmidt

Deem

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

114

140

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Zeolite and zeolite-like molecular sieves are being used in a large number of applications such as adsorption and catalysis. Achievement of the long-standing goal of creating a chiral, polycrystalline molecular sieve with bulk enantioenrichment would enable these materials to perform enantioselective functions. Here, we report the synthesis of enantiomerically enriched samples of a molecular sieve. Enantiopure organic structure directing agents are designed with the assistance of computational methods and used to synthesize enantioenriched, polycrystalline molecular sieve samples of either enantiomer. Computational results correctly predicted which enantiomer is obtained, and enantiomeric enrichment is proven by high-resolution transmission electron microscopy. The enantioenriched and racemic samples of the molecular sieves are tested as adsorbents and heterogeneous catalysts. The enantioenriched molecular sieves show enantioselectivity for the ring opening reaction of epoxides and enantioselective adsorption of 2-butanol (the R enantiomer of the molecular sieve shows opposite and approximately equal enantioselectivity compared with the S enantiomer of the molecular sieve, whereas the racemic sample of the molecular sieve shows no enantioselectivity). chirality | zeolite | asymmetric catalysis | chiral adsorption

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Section: Resultsmentioning

confidence: 99%

Enantiomerically enriched, polycrystalline molecular sieves

Brand

Schmidt

Deem

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

114

140

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“…It has been shown that the presence of silanol defect sites is the most significant factor contributing to crystallinity loss during hydrothermal treatments and that hydrophobic materials tend to be more stable (113)(114)(115)(116). The structural integrity of Lewis acid zeolites is commonly justified with powder X-ray diffraction (PXRD) patterns that are unchanged after reaction, showing that long-range crystal order is preserved (22,25,29,83). However, PXRD is not able to detect partial pore collapse, which can be quantitatively measured using nitrogen or argon adsorption/desorption.…”

Section: Irreversible Deactivationmentioning

confidence: 99%

Lewis Acid Zeolites for Biomass Conversion: Perspectives and Challenges on Reactivity, Synthesis, and Stability

Luo

Lewis

Román‐Leshkov

2016

Annu. Rev. Chem. Biomol. Eng.

150

136

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Zeolites containing Sn, Zr, Hf, Nb, or Ta heteroatoms are versatile catalysts for the activation and conversion of oxygenated molecules owing to the unique Lewis acid character of their tetrahedral metal sites. Through fluoride-mediated synthesis, hydrophobic Lewis acid zeolites can behave as water-tolerant catalysts, which has resulted in a recent surge of experimental and computational studies in the field of biomass conversion. However, many open questions still surround these materials, especially relating to the nature of their active sites. This lack of fundamental understanding is exemplified by the many dissonant results that have been described in recent literature reports. In this review, we use a molecular-based approach to provide insight into the relationship between the structure of the metal center and its reactivity toward different substrates, with the ultimate goal of providing a robust framework to understand the properties that have the strongest influence on catalytic performance for the conversion of oxygenates.

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“…The materials (Sn) SSIE -beta2, (Sn) SSIE -beta3 and (SnAl) SSIE -beta1 exhibited bands characteristic of bulk SnO 2 which are poorly detected in the spectrum of (Sn) SSIE -beta1. The XPS core level spectra of the Sn-containing samples are shown in Figure 8 ( (Figure 8 (b)) [103].…”

mentioning

confidence: 99%

One-pot conversion of furfural to useful bio-products in the presence of a Sn,Al-containing zeolite beta catalyst prepared via post-synthesis routes

Antunes

Lima

Neves

et al. 2015

Journal of Catalysis

133

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Aiming at the valorisation of furfural (Fur) via sustainable routes based on process intensification and heterogeneous catalysis, the one-pot conversion of this renewable platform chemical to useful bio-products, namely furfuryl alkyl ethers (FEs), levulinate esters (LEs), levulinic acid (LA), angelica lactones (AnLs) and -valerolactone (GVL), was investigated using a single heterogeneous catalyst, in 2-butanol, at 120 ºC. Various chemical 2 reactions are involved in this process, which requires catalysts with active sites for acid and reduction chemistry. For this purpose, it was explored for the first time the catalytic potentialities of modified versions of zeolite beta containing Al and Sn sites prepared from commercially available nanocrystaline zeolite beta via post-synthesis partial dealumination followed by solid-state ion-exchange. The post-synthesis conditions influenced considerably the catalytic performances of these types of materials. The best-performing catalyst was (Sn) SSIE -beta1 with Si/(Al+Sn)=19 (Sn/Al=27.6), which led to total yield of bio-products of 83% at 86% Fur conversion, and exhibited steady catalytic performance for six consecutive runs. A systematic catalytic study using the prepared catalysts with different bio-products as substrates, together with the molecular level and microstructural characterisation of the materials, helped understand the effects of different material properties on the specific reaction pathways in the overall system. These studies led to mechanistic insights into the reaction network of Fur to the bio-products in alcohol media, upon which a kinetic model was developed for the first time. The superior performance of (Sn) SSIE -beta1 in various steps was related to the dealumination degree, dispersion and amount of Sn-sites, and acid properties.

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Improved Postsynthesis Strategy to Sn-Beta Zeolites as Lewis Acid Catalysts for the Ring-Opening Hydration of Epoxides

Cited by 265 publications

References 42 publications

Enantiomerically enriched, polycrystalline molecular sieves

Enantiomerically enriched, polycrystalline molecular sieves

Lewis Acid Zeolites for Biomass Conversion: Perspectives and Challenges on Reactivity, Synthesis, and Stability

One-pot conversion of furfural to useful bio-products in the presence of a Sn,Al-containing zeolite beta catalyst prepared via post-synthesis routes

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