Fabrication of Beta Zeolite Enriched in Polymorph E for Highly Efficient Etherification of Furfuryl Alcohol

Zeolite Beta, a prototypical intergrowth zeolite with a three-dimensional (3D) system of intersecting 12-member-ring micropore channels, is extensively employed as a versatile solid-acid catalyst. Its structure typically appears as a nanoscale intergrowth of polymorphs arising from the stacking disorder of topologically equivalent layers. Rational regulation of the Beta polymorph composition is, therefore, crucial for optimizing catalytic performance. Here, we report a heterostructure seed-assisted crystallization strategy to synthesize a polymorph E-enriched Beta zeolite (Beta-ER). The 3D electron diffraction, high-resolution transmission electron microscopy imaging, and DIFFaX simulation show that Beta-ER is an intergrown structure of polymorph E/D with polymorph E as the main phase (∼80%). Powder X-ray diffraction, Fourier transform infrared, Raman, and 19 F magic-angle spinning nuclear magnetic resonance characterizations suggest that ITQ-1 seeds partially deconstruct in the early stage of crystallization and generate secondary structural building units, which subsequently promote the formation of Beta-ER. In the etherification of FA, Beta-ER with moderate acidity and open pore channels delivers a higher furfuryl ethyl ether (FEE) yield (75.4%) after 30 min at 393 K, outperforming the commercial ZSM-5 (14.2%), Beta (55.9%), and BEC (57.2%) zeolites. Beta-ER maintained stable activity after four regeneration cycles. Density functional theory calculations confirm that substituting framework Al with Ge increases the energy barrier for the ring opening of FEE, thereby suppressing the formation of byproducts. In addition, kinetic analysis and molecular dynamics simulations reveal that the interconnected channel system of Beta-ER facilitates the diffusion of substrates and products.