Heteroatom zeolites with a high content of framework metal sites as Lewis-acid catalysts for the conversion of ethanol–acetaldehyde to 1,3-butadiene

Abstract

Heteroatom zeolites possess good Lewis acidity due to heteroatom incorporation in their framework. However, a high incorporation of metals can be hardly achieved because of the weak interactions between the metals and zeolite framework, which limit their catalytic activity. An improved dissolution–reconstruction strategy is proposed in this study for preparing a high content of framework metal sites in heteroatom Zr-β zeolites. The prepared Zr-β zeolite possessed a high Zr content of 5.0 wt% compared to other reported zeolites (1.5 wt% in general), together with more framework Zr sites, better Lewis acidity, and higher mesoporosity. The higher performance is due to the synergistic effect of the parent *BEA framework and the functional agents TEA⁺, OH⁻, and F⁻, as well as the process control. The as-fabricated Zr-β zeolite demonstrated high catalytic performance in the conversion of an ethanol–acetaldehyde mixture to 1,3-butadiene, which was mainly attributed to its high content of framework Zr sites and good diffusion properties resulting from its high mesoporosity.