Biomolecule-inspired synthesis of framework zinc in MFI zeolite for propane dehydrogenation

Abstract

The development of environment-friendly, stable, and efficient catalysts to substitute Pt and Cr-based catalysts for propane dehydrogenation (PDH) is of great importance but challenging to make. Herein, we use zinc gluconate (Zn(C6H12O7)2), an organometallic biomolecule, to embed Zn atoms into pure silica MFI zeolite framework (Zn-MFI) for PDH reaction. Due to the protection by the glucosyl groups in Zn(C6H12O7)2, Zn atoms can be well embedded into the MFI zeolite framework. Multi-scale characterizations (e.g., Cs-corrected HAADF-STEM, FTIR, UV–vis, and NMR spectroscopy) and DFT calculations demonstrate the formation of uniform tetrahedrally coordinated Zn sites in the MFI zeolite framework with two Zn–O–Si and two Zn⋯OH–Si linkages ({(≡SiO)2Zn(HO–Si≡)2}). The Zn-MFI zeolites are used for PDH, exhibiting excellent catalytic performance. Pyridine-FTIR, C3H6-FTIR, C3H6-TPD/MS, and contrast experiments reveal the unique Zn active sites in Zn-MFI zeolites can promote the C–H bond cleavage and weaken the propylene adsorption, thus guaranteeing high activity and selectivity for PDH. The excellent catalytic performance of Zn-MFI zeolites indicates their promising utilization in industry.