Abstract
This paper reports on the control of strong acid sites in SAPO-11 molecular sieve crystals using different silica sources. The crystallization process of the SAPO-11 molecular sieves was performed using silicon sources with different particle sizes, i.e., fumed silica (200 nm), colloidal silica (22 nm), and SiO 2 sol prepared by the sol-gel method (4 nm). The SiO 2 sol proved to have a significant effect on the acidic properties, morphology and crystal size of SAPO-11 molecular sieve. Moreover, more efficient incorporation of silicon is achieved, providing an increased concentration of acid sites. The SAPO-11 intergrown crystals with a size of 100-300 nm exhibited hierarchical pore structure (S BET-250 m 2 /g and V meso-0.27 cm 3 /g) were synthesized using the SiO 2 sol precursor. The SAPO-11 molecular sieves were tested in the reaction of a-methylstyrene dimers synthesis. The SAPO-11 samples, synthesized by SiO 2 sol showed the highest monomer conversion and linear dimer selectivity.