Hydrogenation and ring opening of Tetralin over bifunctional catalysts based on the new ITQ-21 zeolite

The catalytic properties of bifunctional Pt-containing catalysts based on the new large pore Al-containing ITQ-21 zeolite for the hydrogenation and ring opening of tetralin have been evaluated at different reaction temperatures (250–325°C) and 3.0MPa total pressure in the presence of H2. Hydrogenation of tetralin on Pt/ITQ21 was very high (above 99.5%) in the range of temperatures studied. Formation of the high cetane ring-opening products (ROP) was temperature-dependent, and a maximum ROP yield of ∼20wt.% with moderate cracking was found at 300°C for Pt/ITQ21. When compared with bifunctional catalysts based on USY and Beta zeolites having comparable density of Brönsted acid sites, the ITQ21 catalyst displayed higher C10 yields (i.e. lower cracking) at a given temperature, and the highest maximum yield of the desired ROP. These results are explained by considering the particular topology of ITQ-21 favoring the diffusion (and thus reducing the probability of recracking) of the bulky ROP molecules out of the pores as compared with the Y and Beta structures.