Make waste profitable: repurposing SAPO-34 coke from the methanol-to-olefin reaction for luminescent CDs@zeolite composites

It is critical to propose effective and facile methods to decrease the waste of deactivated zeolite catalysts and encourage waste reuse. Herein, we offer an ecologically beneficial concept to transform SAPO-34 coke left over from the methanol-to-olefin reaction into carbon dots (CDs)-confining zeolite composites with multiple luminosities by simple calcination. A batch of CDs-based zeolite composites (CDs@Z-T, CDs@Z-t) was prepared by regulating the calcination temperature and time, which exhibited variable multi-color fluorescence (orange, yellow, green, and blue) as well as green room temperature phosphorescence (RTP) with the longest lifetime of 249 ms. Further research revealed that changing the calcination conditions causes variances in the carbonization and surface functional groups of CDs, leading to tunable luminescence behaviors. The application in time-resolved encryption was realized based on the as-prepared composites. This work provides a novel synthetic route for synthesizing CDs-based composites from catalytic waste.