首页|Aluminum sulphate-assisted stepwise dealumination of OSDA-free low-silica chabazite for methanol-to-olefin reaction
Aluminum sulphate-assisted stepwise dealumination of OSDA-free low-silica chabazite for methanol-to-olefin reaction
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NSTL
The synthesis of chabazite(CHA)aluminosilicate without organic structure-directing agent(OSDA)is a green process,but producing the CHA zeolite with excess acid sites,structural instability and limited applications due to a high aluminum content.Therefore,it is meaningful to develop an effective dealumination method to partially remove the framework aluminum atoms from the OSDA-free low-silica CHA zeolite.A novel stepwise dealumination and stabilization strategy through the subsequent treatment of A12(SO4)3,H2O,HN03 and NH4F was developed,which not only increased the Si/Al ratio from 2.4 to 5.0,but also stabilized the framework structure.Simultaneously,the removal of Al atoms optimized the acidity,introduced mesopores into the CHA framework and enhanced the diffusion property.Compared with low-silica CHA,the obtained high-silica CHA zeolite displayed attractive catalytic performance in methanol-to-olefin(MTO)reaction,showing a methanol conversion above 80% for more than 360 min with a maximum selectivity of 87% for low olefins(C2-C4).
Shanghai Key Laboratory of Green Chemistry and Chemical Processes,School of Chemistry and Molecular Engineering,East China Normal University,North Zhongshan Road 3663,Shanghai,200062,PR China
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