American Chemical Society
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Rational Design of Pomegranate-like Base–Acid Bifunctional β Zeolite by Steam-Assisted Crystallization for the Tandem Deacetalization–Knoevenagel Condensation

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journal contribution
posted on 2020-12-17, 19:40 authored by Hyung-Ki Min, Hyejin An, Dong-Chang Kang, Sungjoon Kweon, Seo-Hyeon Baek, Min Bum Park, Chae-Ho Shin
A highly crystalline pomegranate-like base–acid bifunctional beta zeolite was successfully synthesized by the steam-assisted crystallization method using a basic nitrided N-beta as the starting material. The secondary crystal growth of a beta zeolite generating acid functionality occurred over the outer surface and intercrystalline void spaces of the N-beta zeolite. The pomegranate-like N-beta@H-beta zeolite had a high surface area and base–acid dual functionality because of the well-connected framework topologies of the H-beta and N-beta crystallites. The N-beta@H-beta zeolite exhibited a superior yield of benzylidenemalononitrile during the tandem deacetalization–Knoevenagel condensation of benzaldehyde dimethyl acetal and malononitrile compared to H-beta, N-beta, and their physical mixture. This is likely due to the isolated and balanced activity of the base- and acid-catalyzed reactions.