Understanding the influence of polyvinyl chloride (PVC) on carbon nanotube (CNT) production from waste plastics is essential for enhancing the high-value utilization of real plastic waste. Hence, the influence of chlorine (Cl) on plastic catalytic pyrolysis for CNT formation was investigated from the perspective of Cl in the volatile phase and the catalyst phase, aiming to find the potential strategy to mitigate the impact of Cl. The results showed that catalyst reduction effectively converts Fe 2 O 3 into a more stable Fe 2 AlO 4 spinel structure, thereby safeguarding the active Fe site from deactivation. The carbon yield increased from 17 wt% to 25 wt%, in the instance of real plastic with roughly 10 wt% PVC content. And, at a lower catalytic temperature (600 °C), the catalyst also displays increased resistance to hydrogen chloride (HCl) volatiles. Optimal adjustment of pyrolysis and catalytic temperatures can significantly mitigate catalyst deactivation by Cl and produce CNT with a maximum carbon yield of 28 wt%. This work proposes a pioneering anti-chlorine process designed to recover high-value products from plastic waste, advancing carbon sequestration strategies.
Su Ding,Jinquan Wan,Yan Wang,Zhicheng Yan,Yongwen Ma
In this work, persulfate (PS) activation by a novel functioned metal-organic framework catalyst was investigated for the targeted degradation of DMP, a toxic phthalate pollutant. The catalyst, a molecularly imprinted water-stable Fe-MOF-74 (Fe-MOF-74@SiO 2 @MIP), showed excellent capability of PS activation, high selectivity and efficient targeted degradation performance of DMP. The results of total organic carbon indicated that DMP was mineralized during the catalysis. EPR measurement and quenching experiments suggested the coexistence of SO 4 •− and • OH, and SO 4 •− was predominant in this system. It was found that increasing catalyst loading (0.01 - 0.05 g L -1 ) inhibited the DMP elimination, due to the aggravated radical consumption. A higher pseudo-first order rate of DMP degradation was observed with an increasement of PS (5.2 - 52 mM) and temperature (15 - 45 °C). Besides, coexisting chloride ions (Cl − ) promoted the DMP degradation at the concentration 1 mM, but decreased the degradation performance at other concentrations. According to EPR and XPS analysis, the effect of Cl − was ascribed to the formation chlorine radicals, which changed the radical distribution and the catalytic site property. Chlorinated intermediates were detected by LC-MS, confirming the involvement of Cl-related radicals. Finally, possible degradation pathways were proposed.
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