Extra-large pore JZO zeolites with tunable Si/Al ratios as efficient catalysts for degradable plastic monomer production

Abstract

JZO zeolite, the first stable aluminosilicate extra-large-pore zeolite, bridges the long-standing gap between microporous and mesoporous zeolites, offering highly accessible pore systems that are beneficial for molecular diffusion, active-site accessibility, and the processing of bulky molecules. However, the control of zeolite framework composition is limited, precluding its use in processes that require different acidic and ion-exchange properties. Here, JZO zeolites with tunable framework Si/Al ratios of ca. 15, 30, and 50 were successfully synthesized through precise adjustment of synthesis parameters, thereby broadening the synthesis window of this intriguing zeolite. A series of JZO zeolites was synthesized via a combination of the seed-assisted and the “deficient fluoride” methods. The crystallization kinetics of JZO was prominently boosted compared to the seed-free and fluoride-free counterpart systems, thanks to the accelerated formation of primary building units of JZO. Comprehensive characterization methods were employed to unveil the concerted role of seeds and fluoride ions. Dimethoxymethane carbonylation to methyl methoxyacetate reaction, a promising alternative route for producing degradable plastic monomers, was evaluated over JZO zeolites, and high activity (ca. 58%) and selectivity (ca. 84%) were achieved in JZO zeolite with Si/Al = 30 obtained by seed-assisted approach over a time-on-stream (TOS) test of 50 h. The product distribution could be rationally controlled by adjusting zeolite compositions. This work expands the viability of JZO zeolite synthesis and lays the foundation for practical applications.