Table 5 Summary of Various Plastic Pyrolysis Studies.

HDPE Plastic Pellets (2–4 mm diameter)

Zeolite-based catalyst (\(\hbox {Al}_2\hbox {O}_3\)/\(\hbox {SiO}_2\) ratio = 3.5 40–60 50–57 5.5–6), Kaolin clay catalyst

Bench scale thermocatalytic reactor with continuous feed system

Catalyst Lewis acidity key factor in hydrocarbon fraction and higher acidity encourages tar elimination. Extracted oil is warranted as diesel fuel

Auxilio et al. 40

PE rigid/film, PP rigid/film, PET, PS multilayer flexibles and clogged materials

Without catalyst

Laboratory-scale batch reactor (heating rate of 17 °C min to 500 °C)

Plastic type highly decides the end product. Increasing the PET contribution in the feedstock increases solid products.

Genuino et al. 41

HDPE, LDPE, and PP

MFI-type HZSM-5 zeolite (\(\hbox {SiO}_2\)/\(\hbox {Al}_2\hbox {O}_3\) =23) and an FAU-type spent fluid catalytic cracking (FCC) catalyst

Fixed bed reactor

Catalysts increase the degree of polymer cracking. Gas (75.2 wt%) and liquid (36%) yields are attained, which are substantially higher than without a catalyst. Catalyst acidity and textural properties highly contribute to liquid yield.

Wong et al. 42

~ 62 wt. %PE (~ 38 wt. % HDPE + ~ 24 wt. % LDPE), polypropylene (~ 34 wt. % PP), polyvinyl chloride (~ 3 wt. % PVC), and with about 1 wt. % polystyrene (PS) mixtures.

FCC catalyst

Fluidized bed reactor

The number of accessible sites along with acid sites is important. FT-IR GCMS are used to predict the compounds and their proportion in the extracted oil.

Lin et al. 43

HDPE, LDPE, PP, PS

A zeolite catalyst loaded with nickel (Ni), molybdenum (Mo), and tungstate (W) referred to as (Z-503)

Fixed bed reactor

67.6 wt. %-89.25 wt.% oil yield obtained by thermal pyrolysis in the order PP > LDPE > HDPE > PS by catalytic pyrolysis. 55.1%-68.2% was attained in the order of LDPE > PP > PS > HDPE by thermal pyrolysis.

Khazaal et al. 44

HDPE and small amount of PP

ZSM -5 catalyst

Continuous microwave-assisted pyrolysis

Oil yield 48.9% and it consists of 73.5% gasoline-based hydrocarbon. Adding ZSM -5 catalyst in the secondary bed further increases the oil yield by 48.9%.

Zhou et al. 45

Post-consumer waste plastics

Zeolite catalysts

Lab-scale pyrolysis reactor

Fresh fluidic catalytic cracking reduce the required activation energy for plastic cracking up to 34% and 6.5% at decomposition’s first and second stages.

Kremer et al. 46

Syringes, Medical Bottles

Without catalyst

–

In syringes, thermal cracking occurs at 394.4 to 501 °C, but in medical bottles, this was recorded at 417.9–517  °C.

Ding et al. 47

HDPE and LDPE Medical waste

Natural zeolite \(\hbox {Al}_2\hbox {O}_3\), \(\hbox {SiO}_2\)

Lab scale Pyrolysis Reactor

Aluminum oxide 376 °C and 6.6 wt. % optimist process factors extract 58.3648 and 61.2051 wt. % oil yield. Interaction effect studies depict high acid site catalysts with low temperatures as desirable for both HDPE and LDPE oil yield.

Present study