Catalytic pyrolysis of recycled HDPE, LDPE, and PP

Abstract

Plastic waste has been growing every year, and as a result, environmental concern has been a topic of much attention. Many properties of plastics, such as their lightweight, durability, and versatility, are significant factors in achieving sustainable development. The exponential increase of plastic production produces every year approximately 100 million tons of waste plastic, which could be converted into hydrocarbon fuels by employing a process appropriately called pyrolysis. Pyrolysis, which is thermal or catalytical, can be performed under different experimental conditions that affect the type and amount of product obtained. With the pyrolysis process, products can be obtained with high added value, such as fuel oils and feedstock for new products. In this study, magnesium silicate (MgO3Si) and Cloisite 30B were used as catalysts for the decomposition of different plastics, and the results were compared with the zeolite catalyst. In the case of high-density polyethylene (HDPE), the oil yield with a zeolite catalyst was found to be 71%, whereas with MgO3Si and Cloisite 30B, this was 68% and 67%, respectively. Zeolite produced better results in the decomposition of polypropylene (PP) compared to MgO3Si and Cloisite 30B. Fourier-transform infrared spectroscopy (FTIR), and gas chromatography (GC) were conducted in this work. The spectra results for all samples were consistent and in the fuel range.

Sustainable chemical upcycling of waste polyolefins by heterogeneous catalysis

“…Common catalytic pyrolysis catalysts include various acidic zeolites (ZSM-5, HZSM-5, HY, USY, etc.) [39][40][41][42][43] and catalytic cracking (FCC) catalysts. 44 Both thermal and catalytic pyrolysis proceed together during the reaction process.…”

Effects of mechanical recycling on optical properties and microstructure of recycled high‐density polyethylene pellets and bottles

“…The vibration band located at 718–729 cm −1 corresponds to the swing in the plane of the connections in the methylene group 28 . The bending vibration and symmetry vibration of the CH 2 bonds in the main chain was associated with the signal at 1450–1480 cm −1 29,30 . The signal at 2846–2914 cm −1 was related to CH's symmetric and asymmetric stretching vibrations 31 .…”

Catalytic pyrolysis of waste high-density (HDPE) and low-density polyethylene (LDPE) to produce liquid hydrocarbon using silica-alumina catalyst

“…Over the years, numerous catalysts have been developed for obtaining better gasoline selectivity and converting waste plastics to liquid fuel. Catalysts developed so far for the degradation of polyolefins are mostly based on zeolite HZSM-5 (Aguado et al, 1997;Lin et al, 2004;López et al, 2011;Sivagami et al, 2022), Zeolite-Y (Manos et al, 2001;Shoaib et al, 2021), silicaalumina (SiO 2 -Al 2 O 3 ) (Aguado et al, 1997;Uddin et al, 1997), mesoporousaluminosilicate (MCM-41) (Aguado et al, 1997;Lin et al, 2004), FCC catalysts and clays (Manos et al, 2001;Rahman et al, 2022).…”

“…The combination of ZSM-5/MCM-41 catalyst provided less gaseous product (91.45% gaseous product and 3.58% liquid) than only using ZSM-5 (Lin et al, 2004). Shoaib et al (2021) pyrolyzed HDPE and LDPE using zeolite Y and found that pyrolysis of both HDPE and LDPE provided 71% liquid at 450 C at a catalyst-toplastic ratio of 1:5. Manos et al (2001) used clay and ultrastable Y zeolite to crack HDPE and found that clay catalysts can provide higher amounts of liquid than Y zeolite.…”