At present, since energy depletion and environmental pollution are global issues, many attempts have been made to produce light olefins by low energy consumption, low carbon dioxide emission and environment-friendly methods from coal and natural gas which is more abundant than petroleum or from sustainable biomass resources. One of these methods is the methanol to olefins (MTO) process using a microporous catalyst.
Dimethyl ether (DME) is an intermediate of MTO, and it is easily converted to olefins by catalysis, a surface phenomenon. The key of DTO technology is to synthesize catalysts with high light olefins selectivity and long lifetime. SAPO-18 structure that is extensively used in MTO, DTO, CO2/CH4 separation and SCR of NOx processes, and is structurally similar to SAPO-34 (with CHA framework).
Many attempts have been made to enhance the catalytic performance and lifetime of SAPO-18 catalysts, such as synthesis of catalysts with different organic structure directing agent (OSDA), incorporation of nonmetallic and metallic elements into the framework, and the mechanism of coke formation, but the role of post-acid treatment on DTO performance of SAPO-18 has been barely addressed.
Jong Song Chol, a researcher at the Faculty of Chemical Engineering, has proposed post-HCl treatment as a method to promote DTO performance of SAPO-18, and compared with S-0 and NiS-0 the catalytic performance of acid-treated catalysts such as crystalline structure, morphology, specific surface area, textural properties, acidity and DTO performance.
He has found that the optimum HCl concentration and treating time of SAPO-18 catalyst for the catalytic performance enhancement in DTO are 0.1M and 3h, respectively.
You can find the details in his paper “Efficient post-HCl treatment for promoting DTO performance of SAPO-18 and Ni-substituted SAPO-18” in “Journal of Saudi Chemical Society” (SCI).
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