Synthesis of SAPO-34 Zeolite from Laponite and Its Application in the MTO Reaction

Graphical SAPO-34 zeolite was successfully synthesized from laponite as the single Si source. Laponite itself contains Li and Mg atoms, which were subsequently introduced into the structure of SAPO-34 via depolymerization-reorganization of laponite. Metal incorporation can reduce the amount of stronger acid sites and enhance the catalytic performance in the MTO reaction. In this work, SAPO-34 zeolite with high catalytic activity was successfully synthesized by hydrothermal method from laponite as the single Si source. Compared with the traditional method of synthesizing zeolites from clay, the laponite after swelling can be directly used in the synthesis process of zeolite. The crystallization behavior of SAPO-34 synthesized from laponite was investigated by XRD, FTIR, N 2 adsorption–desorption, SEM-EDX, ICP-MS, and DR-UV/Vis. The process can be summarized as follows: the Si and Mg elements were produced by the depolymerization of laponite, then the primary building units of SAPO-34 zeolite were formed under hydrothermal conditions; finally, the crystal nucleus began to form, and crystallization was triggered. Compared with the conventional SAPO-34 synthesized from TEOS, the SAPO-34 synthesized from laponite exhibited higher selectivity to light olefins and longer lifetime, which can be attributed to the suitable strength of acidity. This work points to a straightforward route to the synthesis of SAPO-34 from laponite.