Uniform Mesoporosity Development in Incorporated β Zeolite: Dual-Template Strategy

The hierarchical porosity of zeolite is a key factor affecting its catalytic activity and stability for bulky molecules involved reactions. However, it is still challenging to introduce mesoporosity into heteroatom-incorporated zeolites in a facile manner while maintaining the catalytic activity. In this work, a strategy for mesoporosity development in incorporated zeolites based on two templates (TEAOH and surfactants) under hydrothermal conditions was proposed, and hierarchical Zr-incorporated β zeolite was successfully prepared and used to catalyze the ETB reaction. In this process, OH– etches the zeolite framework while TEA+ preserves the microporous structure and the 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-β zeolite did not change and the amount of Lewis acid was increased, showing that the mesoporosity could improve the accessibility of active sites. The hierarchical Zr-β zeolite showed better catalytic performance than the parent Zr-β zeolite in the ethanol–acetaldehyde to butadiene reaction, the conversion of ethanol and acetaldehyde can reach 63.7%, and the selectivity of butadiene can reach 76.6%. The stability of hierarchical Zr-β zeolite is significantly higher than that of microporous Zr-β zeolite, whose conversion can be maintained at 35.0% and selectivity at 70.9% at TOS = 24 h. The mesoporosity can increase the capability of coke which mitigates the deactivation.