Experimental study on gasification performance of polypropylene (PP) plastics in supercritical water

In this paper, the gasification performance of polypropylene (PP) plastics in supercritical water was investigated using a quartz tube reactor. A gasification model was demonstrated to reveal the gasification path. Different gasification models were compared to improve gasification efficiency. The response surface methodology (RSM) was employed to find the optimal gasification condition. Moreover, artificial seawater was used for gasification instead of ultrapure water. The results showed that the polypropylene plastic was a difficult gasification substance, the increase in temperature and time had a positive effect on the improvement of gasification, while increasing the feedstock concentration was not conducive to gasification. The optimal condition was 750 °C and 60 min, and the effect of temperature on gasification was more important than time. The gasification model believed that in the initial gasification stage, the easy aromatization of the fragments was key to generating tar. So a 10 wt% formic acid solution was employed to improve gasification, on which the 79.86 wt% of carbon conversion (CE) was obtained. Finally, seawater gasification results showed that seawater components had a positive impact on the gasification of PP plastics, which was an effective way to solve marine microplastics.