Investigation on the thermal stability of La/ZSM-5 zeolite and the La3+ species

By density functional calculations, it was confirmed that for the reaction of rscc (residual oil selective catalytic cracking), the catalysts such as zeolite zsm-5 will endure an enhanced thermal stability when some la3+ ions are introduced. due to the strong interaction between la3+ and the zeolite, the al - o bond, which would have been easily broken, gets stronger and the process of dealumination is thus effectively retarded. through the reduction of la(oh)(2)(+)when heated, lao(oh) is most likely formed, which can interact with zeolite zsm-5 and turns out to the structure of z - la (oh)(2)(+) or z-lao (oh) after geometrical optimization. z - la (oh)(2)(+) remains stable under normal conditions; however, as the temperature is raised, it will change slowly into z-lao(oh), which stays stable at high temperature. the la3+ ion in z-lao (oh) can offer lewis acid as the active site for reactions, we believe that this result can provide valuable insight into the elucidation of catalytic mechanism.