Fabrication of nano-sized SAPO-11 crystals with enhanced dehydration of methanol to dimethyl ether

- A new SIQSC method was first proposed to the formation of nano-SAPO-11.
- Both pre-crystalliztion and ethanol conditions are indispensable to synthesize nano-SAPO-11.
- The role of ethanol was to reduce the growth rate by physical adsorption on the crystal surfaces.
- Nano-SAPO-11 catalyst exhibits the best performance for dehydration of methanol to DMF.

Nano-sized SAPO-11 zeolite was successfully fabricated by a seed-induced quasi-solvothermal conversion (SIQSC) protocol without a secondary porogen that combined an in situ inoculating seed method (SI) and a quasi-solvothermal assisted conversion (QSC) process. The aggregation of SAPO-11 nanocrystals (20-30 nm) to give larger particles with an approximate 200 nm average size creates a lower acidity, larger surface area and higher inter-crystal mesoporosity than those in micro-sized SAPO-11 crystals. Importantly, the nano-sized SAPO-11 shows better performance in the dehydration of methanol to dimethyl ether (DME) than Al2O3 and micro-sized SAPO-11.

Nano-sized SAPO-11 zeolite was successfully fabricated by a seed-induced quasi-solvothermal conversion (SIQSC) protocol without a secondary porogen that combined an in situ inoculating seed method (SI) and a quasi-solvothermal assisted conversion (QSC) process. Ethanol acting as a zeolite growth modifier could inhibit the growth rate of the SAPO-11. Importantly, the Nano-SAPO-11 showed the higher performance for dehydration of methanol to dimethyl ether than that of micro-SAPO-11 due to the higher specific surface and moderate acidity.254