Pyrolysis of bottle‐grade polyethylene terephthalate: Effect of carrier gases on carriage of pyrolysis products

Abstract

The production of widely-used bottle-grade polyethylene terephthalate (PET) is now considered an environmental problem on a global scale. The urgent need for renewable energy reveals the necessity of employing thermochemical recycling methods. The use of a carrier gas is among the parameters affecting the pyrolysis process, for it is responsible for carrying pyrolysis products to separate condensable products. In this study, PET granules were pyrolyzed at 500 C with three carrier gases: N 2 , He, and Ar. According to the results, using a gas with lower molecular weights increased the production of gaseous products (30.94%). However, using a gas with higher molecular weights led to the production of further char (20.2%) associated with the increased reforming reaction rate and hydrogen production in the gaseous phase. The presence of different carrier gases changed tar composition and aromatics; therefore, the highest acid benzoic level was detected in the nitrogen atmosphere. Evaluating the thermal stability of wax and char indicated that the weight loss of char was larger in nitrogen (44.8 wt%) than in the other two carrier gases. However, there were further heavy oxygenated components in wax under the helium and nitrogen atmospheres. Those components degraded more difficultly.

Pyrolysis analysis of polyethylene terephthalate: effects of carrier gases (N2, He, and Ar) and zeolite catalyst (A4) on yield

“…Since the benzoic acid and methyl radicals reacted violently, the intensity of 1,4‐dimethylbenzoate measured in the presence of argon rose nonlinearly. The argon atmosphere had the lowest biphenyl concentration, which was consistent with the clearly visible rise 29 …”

“…This finding showed that the wax generated in the helium and nitrogen atmospheres included higher concentrations of heavy oxygenated species. With the temperature rising, they were tough to decompose and progressively polymerize 29 …”

“…The argon atmosphere had the lowest biphenyl concentration, which was consistent with the clearly visible rise. 29 UV-fluorescence spectroscopy Figure 2 shows the UV results of the liquid product samples. As shown, the aromatics in the product consisted of a wide range of groups, from groups with a single benzene ring to those with multiple benzene rings (polycyclic aromatics).…”

“…With the temperature rising, they were tough to decompose and progressively polymerize. 29 Catalyst characterization Elemental analysis Table 5 shows the elemental analysis results of the catalyst samples after the test. The results revealed hydrocarbons on zeolite arising from coke deposition on the catalyst.…”

Role of Different Catalysts on a Direct Growth Carbon Nanotube for Supercapacitor Electrodes

“…Under vacuum conditions, argon is used to create the inert gas atmosphere and purge any additional contaminants in the substrate. Either hydrogen or nitrogen gases are used to react at the surface and to maintain the high temperature and pressure of the substrate. , Precursor gases such as carbon monoxide, ethane, ethylene, acetylene, benzene, and xylene mostly contain carbon sources. Methane, ethylene, and acetylene have linear dimmers of carbon atoms and they form a straight CNT, while benzene produces a curved CNT. , Acetylene has a major influence on CNT production manufactured by the CVD method.…”