Decomposition of Gaseous Terephthalic Acid in the Presence of CaO

Abstract

The decomposition of PET during thermal treatment of municipal waste results in the formation of sublimating substances such as terephthalic acid (TPA) and benzoic acid, causing blockage and corrosion of pipes in the treatment facilities. To prevent these effects, TPA can be decarboxylated in the presence of calcium oxide (CaO) to obtain benzene as the main product. However, high concentrations of TPA cause the formation of large char fractions, reducing the yield of desired products. In this investigation, TPA was decarboxylated using a fixed-bed reactor filled with CaO. To increase the yield of benzene and reduce the carbonaceous residue, the effects of pyrolysis temperature and TPA feed rate were investigated. The best results were achieved at 500 °C and a TPA feed rate of 51 mg L -1 , yielding 67% benzene with a purity of 99.2% and a carbonaceous residue containing 18% of the initial carbon.

Current state and future prospects of plastic waste as source of fuel: A review

“…On the other hand, studies by Kumagai and Grause [108,109] indicated that terephthalic acid (TPA) can be formed from pyrolysis of PET, and it can be converted to benzene in the presence of calcium oxide (CaO) under suitable conditions. However, without careful control of reaction condition, secondary reactions cause char formation.…”

Scale‐Up Synthesis of High Purity Calcium Terephthalate from Polyethylene Terephthalate Waste: Purification, Characterization, and Quantification

“…According to the methods proposed by Steinmeyer et al, [33,34] the yield of metal-terephthalate can be calculated from the ratio of weight loss above 520 °C, but the value also relies on the assumption that all the residue is metal oxide. When it comes to CaTP, the decarbonation of TPA and subsequently CaCO 3 at a temperature above 500 °C has been verified by Du et al [42] and Kumagai et al, [43] suggesting the TGA residue to be CaO. In this way, the concentration and molar yield of CaTP in Ca-PET can be estimated by the following two equations…”

Toward Making Poly(ethylene terephthalate) Degradable in Aqueous Environment

“…More importantly, the aromatic in‐plane bending vibration of C‐H appeared at 1149, 1097, and 1021 cm –1 , the out of plane bending vibration of C‐H appeared at 754 cm –1 , the carboxylic deformation vibration appeared at 810 cm –1 , and the stretching vibration of C═C appeared at 1502 cm –1 all suggest the formation of calcium terephthalate (abbreviated as CaTPA) in the hydrolysis product of the 75/25 PET/CaO composite material. [ 18 ]…”