Preparation of SSZ-13 zeolites from beta zeolite and their application in the conversion of ethylene to propylene

For the first time, beta zeolites (IZA code: BEA with 12-membered rings, having a wide range of SiO₂/Al₂O₃) were converted into SSZ-13s (IZA code CHA, having 8-membered rings) in the presence of external silica source (here, Na₂SiO₃) and N,N,N-trimethyl-1-adamantanamine hydroxide as a structure directing agent. Na₂SiO₃ was essential for the successful conversion when the parent zeolite beta was Al-rich. The conversion of beta into SSZ-13 zeolite can be explained by the relative stabilities of beta and SSZ-13 zeolites, where pore size had more dominant role than the framework density. The obtained SSZ-13s were highly porous, had both weak and strong acidic sites and composed of tetrahedral aluminum. Finally, the synthesized SSZ-13s were applied in the direct conversion of ethylene-to-propylene (ETP) as a solid catalyst. The results showed that the SSZ-13s, converted from beta, were better or competitive in ETP (especially in the stable conversion of ethylene) against the SSZ-13 (synthesized by using tetraethylammonium hydroxide) that had showed very competitive performances earlier in ETP.