Direct Polypropylene and Polyethylene Liquefaction in CO2 and N2 Atmospheres Using MgO Light and CaO as Catalysts

Abstract

The polyolefin to lighter molecules reaction reduces the waste-plastic residues to produce fuels and valuable chemicals. Commercial MgO light and CaO were used as catalysts for the direct polyethylene and polypropylene liquefaction in N2 or CO2 atmospheres. The products were analyzed (ATR-FTIR, GC-FID/TCD, GC-FID, density, refractive index). The use of MgO light and CaO improved the conversion of propylene and ethylene to liquid products. In addition, low gaseous and solid products yields were obtained. A good production of organic liquids in the gasoline, diesel and kerosene boiling range was obtained. The use of CO2, in some cases, led to a higher conversion into liquids compared with the reactions performed in the N2 atmosphere. In addition, the use of the CO2 atmosphere led to a higher content of products with a boiling range in the diesel and kerosene ranges.

Thermal and catalytic pyrolysis of a real mixture of post-consumer plastic waste: An analysis of the gasoline-range product

“…In all the liquids, the predominant product was gasoline, with yields between 57.7 % (MgO) and 45.3 % (HZSM-5 zeolite). Comparable gasoline yields were obtained by Hidalgo et al [36] using MgO and CaO. Also, Anene et al [52] in catalytic pyrolysis with zeolite at 460 ºC, obtained a similar gasoline yield (45.6 %).…”

“…It is an effect that should be minimized since it inhibits the catalytic activity and increases the costs for the regeneration of the catalyst [59]. Xue et al [32] in the ex-situ catalytic pyrolysis at 600 ºC of PE, PP, PET, and PS over HZSM-5 zeolite or Hidalgo et al [36] in the catalytic pyrolysis of PE and PP over CaO and MgO reported similar coke deposition data. Other authors also reported gases, liquid, and solid yields, of catalytic pyrolysis of different plastics (see Table S1).…”

“…MgO and CaO were also used as catalysts for the pyrolytic conversion of PE and PP. These lowcost catalysts improved the conversion to liquid products, decreasing the gas and char yields and producing liquid results in the gasoline, diesel, and kerosene range was achieved [36].…”