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

Flat-panel display plastics are a growing part of e-waste, posing recycling challenges due to toxic additives and metals. Pyrolysis and the use of the resulting hydrocarbon products in the petrochemical industry offer a sustainable solution. Tested acid zeolites during pyrolysis significantly increased the BTEX fraction yield (Hβ enhanced more benzene, while HY enhanced ethylbenzene), though they also produced polycyclic aromatic hydrocarbons. They also successfully reduced unwanted heteroatoms like nitrogen- and oxygen-containing compounds and styrene, which can interfere with further pyrolysis product applications.

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.

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