Continuous flow synthesis of visible light-active conjugated porous polymer for pollutant degradation and plastic waste photoreforming

Developing metal free, visible light active photocatalysts is a green and sustainable approach towards environmental remediation and energy generation. Here, we present a sulfone based conjugated porous organic polymer (CPOP) as a visible light active catalyst for the photocatalytic degradation of pollutants, and photo -reformation of waste plastic into green hydrogen, and other value-added products. High temperature (120 degrees C) refluxing of 3, 3 ' diamino diphenylsulfone (APS) and 1, 3, 5-Triformylphloroglucinol (TFP) for 10 h yielded APS-TFPBatch. When compared to the traditional batch approach, the continuous flow method allowed the synthesis of APS-TFPFlow in less time (3 h) and lower temperature (60-70 degrees C) because of efficient heat and mass transfer. The APS-TFPFlowCPOP had higher surface area, dispersibility, optical absorbance, charge separation, and transportation characteristics than APS-TFPBatch. Thus, APS-TFPFlow was found to be a better photocatalyst for the degradation of a model pollutant, methylene blue (MB) than APS-TFPBatch. Additionally, performing the pho-tocatalytic degradation of MB in continuous flow led to further enhancement in the photocatalytic pollutant removal (96%) than in batch (74%). Moreover, the catalyst could be reactivated efficiently in the flow process for repeated usage.Additionally, photoreforming of polyethylene terephthalate (PET) waste bottles in presence of APS-TFPFlow under visible light irradiation resulted in the generation of high amount of green hydrogen (77 mmol/gcat/h) along with terephthalate, lactate and glycolate. Thus, the present study emphasises the advantages of using continuous flow method for the synthesis of CPOP as well as for performing photocatalytic reactions.

Automated summary

Developing metal-free, visible light active photocatalysts is crucial for environmental remediation and energy generation. In this study, a sulfone-based porous organic polymer was synthesized as a visible light active catalyst for pollutant degradation and waste plastic conversion. The continuous flow method allowed for faster synthesis and improved catalytic performance compared to the traditional batch approach. The catalyst showed enhanced efficiency in pollutant degradation and could be efficiently reused in the flow process. The photoreforming of waste plastic resulted in the generation of green hydrogen and other value-added products.