(178g) Air and Air/Steam Gasification of Polymers in a Semi-Batch Reactor System for H2 and CO Production

Plastic waste is steadily becoming one of the most important environmental issues of the 21^st century. The need to develop waste polymer recycling technologies to address this issue is constantly growing with the increase in worldwide plastic production. In this context, the adaptation of proven chemical processes, such as gasification, could address this emerging issue. With this in mind, the feasibility of waste plastic gasification in small scale batch reactors was investigated to identify pathways to developing this technology for industrial purposes. Small scale batch reactors have the potential to be implemented and operated by a diverse range of organizations, making them more versatile than their traditional counterparts. These small scale reactors could help organizations maintain some energy independence while simultaneously minimizing the waste they produce. Polymer gasification experiments were designed and performed in a semi-batch reactor with air or air/steam as the inlet stream to study the production of hydrogen and carbon monoxide in the reactor. We screened various polymers and found that high density polyethylene (HDPE) showed the highest H₂ and CO yield for both air and air/steam runs at a temperature of 1073 K. We observed that the presence of steam in the reactor drastically increased the production of hydrogen due to the water gas shift reaction and steam reforming reactions. We further noted that lower temperatures resulted in the pyrolysis of the polymers instead of their gasification.

Ongoing experiments with Ni-based reforming catalysts evince increased hydrogen production, which is attributed to the reforming of pyrolysate hydrocarbons to hydrogen and CO, potentially enabling lower-temperature operation and energy savings.