Catalytic Pyrolysis of Waste Flat-Panel Display Plastics for Valuable Hydrocarbons

Catalytic pyrolysis of waste flat-panel display (FPD) plastics and pure polystyrene (PS), which is the main polymer component in FPD waste, is conducted at 500 °C in a micropyrolysis reactor to enhance benzene, toluene, ethylbenzene, and xylene (BTEX) production and eliminate styrene and heteroatom compounds in pyrolysis products. A comparative study with PS reveals similar product distributions, indicating that FPD waste additives do not significantly impede the catalytic reactions. Zeolitic catalysts (HZSM-5, Hβ, and HY) effectively reduce nitrogen- and oxygen-containing compounds and also styrene with increase in BTEX and polycyclic aromatic hydrocarbons (PAHs) yields. Even at a feed:catalyst ratio of 1:1, distinct product distributions are observed compared to the noncatalytic run. In the presence of Hβ, benzene is the main compound, exhibiting a 22% increase. With HY, ethylbenzene is the dominant product, showing a 36% increase. Notably, HY, which possesses the highest concentration of Brønsted acid sites with minimum of Lewis acid sites together with the largest pore size among the studied zeolites, preferentially enhances the formation of ethylbenzene within the BTEX.