Atmospheric pressure synthesis of nano-scale SAPO-34 catalysts for effective conversion of methanol to light olefins†
Nano-scale SAPO-34 zeolites were successfully synthesized under atmospheric pressure for the first time through a dry gel conversion route with the assistance of magnesium aluminum silicate (Al2MgO8Si2). Under atmospheric pressure, the crystallization, calcination, and even catalytic evaluation of SAPO-34 can be carried out consecutively in the same fixed-bed reactor. Characterization and systematic studies indicated that the use of crystal seeds can improve the relative crystallinity of SAPO-34, and the as-synthesized SAPO-34 exhibits relatively high crystallinity, a high surface area and a uniform crystal size of 25 nm. Compared with conventional SAPO-34, the nano-scale SAPO-34 exhibited a higher selectivity to light olefins (83.6%) when methanol is completely converted. These results offer a potential way to synthesize zeolites by a safe and sustainable process under atmospheric pressure.