Print Email Facebook Twitter Electronic Structure Analysis of the Diels-Alder Cycloaddition Catalyzed by Alkali-Exchanged Faujasites Title Electronic Structure Analysis of the Diels-Alder Cycloaddition Catalyzed by Alkali-Exchanged Faujasites Author Rohling, Roderigh Y. (Eindhoven University of Technology) Tranca, Ionut C. (Eindhoven University of Technology) Hensen, Emiel J.M. (Eindhoven University of Technology) Pidko, E.A. (TU Delft ChemE/Algemeen; Eindhoven University of Technology) Date 2018-07-05 Abstract The Diels-Alder cycloaddition (DAC) reaction is a commonly employed reaction for the formation of C-C bonds. DAC catalysis can be achieved by using Lewis acids and via reactant confinement in aqueous nanocages. Low-silica alkali-exchanged faujasite catalysts combine these two factors in one material. They can be used in the tandem DAC/dehydration reaction of biomass-derived 2,5-dimethylfuran (DMF) with ethylene toward p-xylene, in which the DAC reaction step initiates the overall reaction cycle. In this work, we performed periodic density functional theory (DFT) calculations on the DAC reaction between DMF and C2H4 in low-silica alkali(M)-exchanged faujasites (MY; Si/Al = 2.4; M = Li+, Na+, K+, Rb+, Cs+). The aim was to investigate how confinement of reactants in MY catalysts changed their electronic structure and the DAC-reactivity trend among the evaluated MY zeolites. The conventional high-silica alkali-exchanged isolated site model (MFAU; Si/Al = 47) served as a reference. The results show that confinement leads to initial-state (IS) destabilization and transition-state (TS) stabilization. Among the tested MY, most significant IS destabilization is found in RbY. Only antibonding orbital interactions between the reactants/reactive complex and cations were found, indicating that TS stabilization arises from ionic interactions. Additionally, in RbY the geometry of the transition state is geometrically most similar to that of the initial and final state. RbY also exhibits an optimal combination of the confinement-effects, resulting in having the lowest computed DAC-activation energy. The overall effect is a DAC-reactivity trend inversion in MY as compared to the trend found in MFAU where the activation energy correlates with the Lewis acidity of the exchangeable cations. To reference this document use: http://resolver.tudelft.nl/uuid:47112760-f1cd-461c-bf65-dd5d36039f9e DOI https://doi.org/10.1021/acs.jpcc.8b04409 ISSN 1932-7447 Source The Journal of Physical Chemistry C, 122 (26), 14733-14743 Part of collection Institutional Repository Document type journal article Rights © 2018 Roderigh Y. Rohling, Ionut C. Tranca, Emiel J.M. Hensen, E.A. Pidko Files PDF acs.jpcc.8b04409_1.pdf 8.52 MB Close viewer /islandora/object/uuid:47112760-f1cd-461c-bf65-dd5d36039f9e/datastream/OBJ/view