This study investigated hydrothermal liquefaction (HTL) of polyethylene (PE) with different amounts (ranging from 1 wt.% to 19 wt.%) of calcium carbonate (CaCO3). The role and the fate of CaCO3 in HTL was elucidated under different reaction conditions (425-450 °C for 1-2 h). At 450°C-2 h, the oil yield (~80%) obtained was higher than that from 425°C-1.5 h (~60%). However, with higher reaction temperatures (450°C) and longer reaction times (2 h), a higher gas yield (25%) was also achieved. The gas chromatography-mass spectrometry (GC-MS) analysis revealed that the oil product obtained with different amounts of CaCO3 exhibited a similar composition at 425°C for 1.5 h and 2 h, mostly composed of paraffin and olefins with carbon numbers ranging from C7 to C17. At 450°C-2 h, the oil product was predominantly aromatics for all PE samples with different amounts of CaCO3. Additionally, inductively coupled plasma optical emission spectroscopy analysis showed that over 90% of Ca was distributed to the post-HTL aqueous products, indicating that HTL can simultaneously remove contaminants such as CaCO3 while chemically recycling PE waste into valuable products like fuels or aromatic chemicals. To understand the complex reactions during HTL of PE with varying amounts of CaCO3, the key reactions were investigated using quantum mechanical (QM) methods to elucidate possible reaction mechanisms involved. Finally, the presenter will dedicate a small portion of their presentation to give a short introduction to their story and career path. Recent studies on catalytic HTL of plastic waste will also be briefly highlighted.
