Uniform Mesoporosity Development in Incorporated beta Zeolite: Dual-Template Strategy br

The hierarchical porosity of zeolite is a key factoraffecting its catalytic activity and stability for bulky moleculesinvolved reactions. However, it is still challenging to introducemesoporosity into heteroatom-incorporated zeolites in a facilemanner while maintaining the catalytic activity. In this work, astrategy for mesoporosity development in incorporated zeolitesbased on two templates (TEAOH and surfactants) underhydrothermal conditions was proposed, and hierarchical Zr-incorporated beta zeolite was successfully prepared and used tocatalyze the ETB reaction. In this process, OH-etches the zeoliteframework while TEA+preserves the microporous structure andthe surfactant as the mesoporogen. The mesopore size (2.1-3.2 nm) can be tailored by changing the alkyl chain length (C10-C16)of the surfactant. During the treatment, the chemical environment of Zr in Zr-beta zeolite did not change and the amount of Lewis acidwas increased, showing that the mesoporosity could improve the accessibility of active sites. The hierarchical Zr-beta zeolite showedbetter catalytic performance than the parent Zr-beta zeolite in the ethanol-acetaldehyde to butadiene reaction, the conversion ofethanol and acetaldehyde can reach 63.7%, and the selectivity of butadiene can reach 76.6%. The stability of hierarchical Zr-beta zeoliteis significantly higher than that of microporous Zr-beta zeolite, whose conversion can be maintained at 35.0% and selectivity at 70.9% atTOS = 24 h. The mesoporosity can increase the capability of coke which mitigates the deactivation.