Synthesis of SAPO-34 with modifying Si distribution by seed-assisted method and its excellent catalytic performance for methanol to olefins

Abstract

Low acidity SAPO-34 was synthesized by adding seeding SAPO-34 as Si source without additional Si reagent, named as CSSAPO-34-x (x = 1, 2, 3) according to the seeding SAPO-34 content for 6 wt%, 8 wt% and 9 wt%, respectively. The characterizations prove that the CSSAPO-34-x samples display much lower Si content and acidity, good catalytic performance and light olefins selectivity in methanol to olefins (MTO) process compared with the seeding SAPO-34 and the similar Si content SAPO-34 synthesized in one pot procedure. Further studies demonstrate that Si distribution can be manipulated when the seeding SAPO-34 is recrystallized by the hydrothermal treatment, decreasing the acidity of the CSSAPO-34-x, leading to much better catalytic MTO performance.