Rational
Design of Pomegranate-like Base–Acid Bifunctional β Zeolite
by Steam-Assisted Crystallization for the Tandem Deacetalization–Knoevenagel
Condensation
posted on 2020-12-17, 19:40authored byHyung-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.