Selective syngas conversion to olefins over bifunctional Zn₂Al₃O₄/PLS-3 catalyst

Designing zeolites with novel topologies and tunable acidity to construct metal oxide-zeolite bifunctional catalytic systems for targeted transformation of syngas into high-value olefins has aroused wide interest. PLS-3 aluminosilicates with the FER topology and unique nanorod crystal morphology, derived from layered precursors with a wide Si/Al ratio range of 50-300, were applied to combine with Zn2Al3O4 oxide, constructing bifunctional catalysts for selective syngas conversion reaction. The lower Al content in PLS-3 zeolite led to decreased acid amount and the preferred distribution of framework Al atoms in specific tetrahedral locations (T2 and T4), which promoted the formation of ethylene. High-silica PLS-3 (Si/Al = 250) combined with Zn2Al3O4 oxide showed high selectivity for C2-5= (78.5%), especially for ethylene (45%), and high ratios of ethylene to propylene (E/P , 7.0) and olefin to paraffin (O/P , 21.2). Furthermore, the in-situ infrared spectra evidenced that the syngas conversion over Zn2Al3O4/PLS-3 catalyst possibly followed the carbonylation route.