Silicoaluminophosphate (SAPO) molecular sieves have opened new perspectives in the conversion process of dimethyl ether to olefins (DTO) and recently, SAPO-18 catalysts with enhanced stability have been reported as catalysts for DTO reactions.
SAPO-18 is a microporous crystal of the AEI-type framework, in which only dimethyl ether (DME), light olefins and linear hydrocarbons can pass through the pores, while aromatic intermediates formed inside the pores cannot. This leads to coke deposition by the growth of aromatic intermediates during reactions, and the deposited coke blocks the pore entrance of the catalyst, leading to deactivation.
Therefore, it is necessary to improve the performance of catalysts that can delay their deactivation in the DTO reaction using the SAPO-18 catalyst.
Ho Yu Gyong, a researcher at the Institute of Nano Science and Technology, has steam-treated the hydrothermally synthesized SAPO-18 catalyst to investigate the catalytic performance in dimethyl ether to olefins (DTO) reactions.
After steam treatment, micropores and mesopores were created on the SAPO-18 catalyst.
To evaluate the catalytic activity of steamed SAPO-18, she carried out a DTO reaction at 673K with weight hourly space velocity (WHSV) of 3.546h-1. The result showed that the steamed SAPO-18 (S-773) steamed at 773K exhibited excellent DTO conversion performance.
You can find the details in her paper “Steam-treated SAPO-18 with well-regulated acidity and excellent DTO performance” in “Journal of the Indian Chemical Society” (SCI).