Route to Renewable PET: Reaction Pathways and Energetics of Diels鈥揂lder and Dehydrative Aromatization Reactions Between Ethylene and Biomass-Derived Furans Catalyzed by Lewis Acid Molecular Sieves

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• 作者：Joshua J. Pacheco ; Jay A. Labinger ; Alex L. Sessions ; Mark E. Davis
• 刊名：ACS Catalysis
• 出版年：2015
• 出版时间：October 2, 2015
• 年：2015
• 卷：5
• 期：10
• 页码：5904-5913
• 全文大小：498K
• ISSN：2155-5435

文摘

Silica molecular sieves that have the zeolite beta topology and contain framework Lewis acid centers (e.g., Zr-尾, Sn-尾) are useful catalysts in the Diels鈥揂lder and dehydrative aromatization reactions between ethylene and various renewable furans for the production of biobased terephthalic acid precursors. Here, the main side products in the synthesis of methyl 4-(methoxymethyl)benzene carboxylate that are obtained by reacting ethylene with methyl 5-(methoxymethyl)-furan-2-carboxylate are identified, and an overall reaction pathway is proposed. Madon鈥揃oudart experiments using Zr-尾 samples of varying Si/Zr ratios clearly indicate that there are no transport limitations to the rate of reaction for the synthesis of p-xylene from 2,5-dimethylfuran and ethylene and strongly suggest no mass transport limitations in the synthesis of methyl p-toluate from methyl 5-methyl-2-furoate and ethylene. Measured apparent activation energies for these reaction-limited systems are small (<10.5 kcal/mol), suggesting that apparent activation energies are derived from a collection of parameters and are not true activation energies for a single chemical step. In addition, ¹³C kinetic isotope effects (KIE) in the synthesis of MMBC and MPT measured by gas chromatography/isotope-ratio mass spectrometry in reactant-depletion experiments support the Madon鈥揃oudart result that these systems are not transport-limited and the KIE values agree with those previously reported for Diels鈥揂lder cycloadditions.