Method for estimating the heat of chemical reaction of polyethylene terephthalate and method for thermal decomposition treatment of polyethylene terephthalate
By estimating the heat of chemical reaction of PET using standard enthalpy of formation, the method addresses the challenge of unpredictable thermal decomposition, enabling optimized PET recycling processes.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NIPPON STEEL CORPORATION
- Filing Date
- 2024-12-05
- Publication Date
- 2026-06-17
Smart Images
Figure 2026098849000001_ABST
Abstract
Description
[Technical Field]
[0001] This disclosure relates to a method for estimating the heat of chemical reaction of polyethylene terephthalate and a method for thermal decomposition treatment of polyethylene terephthalate. [Background technology]
[0002] As a method for processing used plastics, a technology is known that involves thermally decomposing the waste plastic (used plastic) and recycling it as a resource such as thermal decomposition oil (see, for example, Patent Document 1).
[0003] Patent Document 2 discloses a pyrolysis apparatus for pyrolyzing waste plastics, comprising: a pyrolysis tank for containing waste plastics; a heating means provided within the pyrolysis tank for heating the waste plastics in the pyrolysis tank; and a control means for controlling the amount of heating by the heating means in order to adjust the temperature inside the pyrolysis tank.
[0004] Patent Document 3 discloses a method for decomposing polyethylene terephthalate in a waste plastic mixture, which enables the recycling of only polyethylene terephthalate from a mixture containing multiple types of plastic materials. This method involves heating a waste plastic mixture containing polyethylene terephthalate and a chlorine-containing polymer in an airtight container to a temperature of 200°C to 330°C to separate a mixture of terephthalic acid, mono(2-chloroethyl) terephthalate, and bis(2-chloroethyl) terephthalate. [Prior art documents] [Patent Documents]
[0005] [Patent Document 1] Patent No. 7456560 [Patent Document 2] Japanese Patent Publication No. 2012-17441 [Patent Document 3] Japanese Patent Publication No. 2024-006038 [Overview of the project] [Problems that the invention aims to solve]
[0006] When waste plastics are thermally decomposed and recycled as fuel or other materials by gasification or liquefaction (oil conversion), exothermic or endothermic reactions occur depending on the type of waste plastic. Therefore, in the thermal decomposition treatment of waste plastics, it is important to determine the appropriate specifications of the thermal decomposition process according to the type of waste plastic being treated.
[0007] In particular, the molecular structure of PET (polyethylene terephthalate) is a polymer in which a relatively long number of bond units (e.g., terephthalic acid + α) are repeated n times, compared to PE, PP, PS, and PVC. Therefore, the type and combination of thermal decomposition products change depending on which bonds within the PET unit structure are broken during thermal decomposition. For this reason, it is desirable to evaluate the heat of thermal decomposition reaction while taking these characteristics of PET into consideration.
[0008] This disclosure aims to provide a method for estimating the heat of chemical reaction of polyethylene terephthalate and a method for thermal decomposition treatment of polyethylene terephthalate. [Means for solving the problem]
[0009] The above problems will be solved by the following means. <1> Representing polyethylene terephthalate in units of molecular components smaller than the repeating unit, The standard enthalpy of formation of the aforementioned molecular constituent units is estimated stoichiometrically using known data on the heat of complete combustion, and Based on the estimated standard enthalpy of formation of the aforementioned molecular constituent units, the amount of endothermic and exothermic reactions of the polyethylene terephthalate is estimated. A method for estimating the heat of chemical reaction of polyethylene terephthalate containing [a specific substance]. <2> We assumed multiple reaction patterns for the chemical reaction of polyethylene terephthalate. <1> The endothermic and exothermic amounts of each reaction pattern are estimated using the estimation method described above. To measure the production ratio of reaction products generated by the chemical reaction of polyethylene terephthalate. The combination ratio of the reaction pattern is determined based on the measured production ratio of the reaction product, and The amount of endothermic and exothermic reactions of polyethylene terephthalate is estimated by weighting the amount of endothermic and exothermic reactions of each reaction pattern, taking into account the combination ratio. including <1> A method for estimating the heat of chemical reaction of polyethylene terephthalate as described above. <3> We assumed multiple reaction patterns for the chemical reaction of polyethylene terephthalate. <1> The endothermic and exothermic amounts of each reaction pattern are estimated using the estimation method described above. To measure the production ratio of reaction products generated by the chemical reaction of polyethylene terephthalate. The combination ratio of the reaction pattern is determined based on the measured production ratio of the reaction product, and By simply averaging the endothermic and exothermic amounts of each reaction pattern, the endothermic and exothermic amounts of the chemical reaction of polyethylene terephthalate can be estimated. including <1> A method for estimating the heat of chemical reaction of polyethylene terephthalate as described above. <4> <1> ~ <3> To estimate the heat of reaction in the thermal decomposition treatment of polyethylene terephthalate by using the method for evaluating the heat of chemical reaction of polyethylene terephthalate described in any one of the following: Based on the estimated heat of reaction, the specifications for the thermal decomposition process of polyethylene terephthalate are determined, and The thermal decomposition treatment of polyethylene terephthalate is carried out according to the determined thermal decomposition process specifications. A method for thermal decomposition treatment of polyethylene terephthalate containing [a specific substance]. [Effects of the Invention]
[0010] According to the present disclosure, there are provided a method for estimating the heat of chemical reaction of polyethylene terephthalate and a method for thermally decomposing polyethylene terephthalate.
Brief Description of the Drawings
[0011] [Figure 1] It is a diagram showing an example of a method for calculating the standard enthalpy of formation per mole of carbon of benzene. [Figure 2] It is a diagram showing an example of a method for calculating the standard enthalpy of formation per mole of carbon of polypropylene. [Figure 3] It is a diagram showing an example of a method for calculating the standard enthalpy of formation per mole of carbon of PET. [Figure 4] It is a diagram showing an example of a reaction stoichiometry formula for thermal decomposition of PET. [Figure 5] It is a diagram showing four reaction patterns considered as thermal decomposition of PET.
Embodiments for Carrying Out the Invention
[0012] A method for estimating the heat of chemical reaction of polyethylene terephthalate (PET) according to the present disclosure (hereinafter, may be abbreviated as "the estimation method of the present disclosure") and a method for thermally decomposing polyethylene terephthalate will be described.
[0013] When determining the heat absorption or release of a certain reaction, it is common to evaluate the increase or decrease in the standard enthalpy of formation for the substances before and after the reaction. Waste plastics are a mixture composed of various polymer compounds (plastics). However, there is no concept of evaluating polymer compounds in terms of the enthalpy of formation, nor is there a definition of the enthalpy of formation. Therefore, no matter how many physical property value tables are investigated, there is no literature that describes the enthalpy of formation for polymer compounds such as PE, PP, PS, PET, PVC, and PVCD, which are typical components of waste plastics. What is usually described in the physical property value table of polymer compounds is only the heat of complete combustion.
[0014] On the other hand, when evaluating the heat of thermal decomposition or incomplete combustion of these polymer compounds, it is highly advantageous to use standard enthalpy of formation rather than the heat of complete combustion, as this allows for stoichiometric evaluation before and after the reaction.
[0015] Therefore, the inventors of this disclosure investigated methods for effectively utilizing physical property information such as the heat of complete combustion of polymer compounds, and attempted to devise a method for estimating physical property values equivalent to the standard enthalpy of formation for polymer compounds. As a result, they discovered a method for estimating the heat of chemical reaction of polyethylene terephthalate according to this disclosure. In other words, the method for estimating the heat of chemical reaction of polyethylene terephthalate according to this disclosure is: Representing polyethylene terephthalate in units of molecular components smaller than the repeating unit, The standard enthalpy of formation of the aforementioned molecular constituent units is estimated stoichiometrically using known data on the heat of complete combustion, and Based on the estimated standard enthalpy of formation of the aforementioned molecular constituent units, the amount of endothermic and exothermic reactions of the polyethylene terephthalate is estimated. Includes.
[0016] Known data on the heat of complete combustion include literature data and experimental data. This method allows us to estimate the standard enthalpies of formation of each substance before and after a chemical reaction involving PET, thereby enabling us to appropriately evaluate the heat of reaction. As a result, for example, it becomes possible to provide important information for determining the appropriate specifications of a thermal decomposition process when designing a process for thermally decomposing PET.
[0017] The method for estimating the heat of chemical reaction of PET in this disclosure involves reducing the molecular components of PET to a level where a stoichiometric reaction equation can be easily constructed, and defining the enthalpy of formation at the molecular component level. The estimation method in this disclosure is fundamentally based on this idea. Since polymer compounds are generally composed of carbon, ultimately, if it can be converted to the "standard enthalpy of formation per mole of carbon," it will be possible to apply this method to the reaction evaluation of many polymer compounds.
[0018] For example, while it is not necessary to convert to the "standard enthalpy of formation per mole of carbon" for monomolecules, we will use benzene as an example to explain how to convert to the "standard enthalpy of formation per mole of carbon" from the heat of combustion of hydrocarbon compounds. Figure 1 shows an example of how to calculate the standard enthalpy of formation per mole of carbon, using benzene as an example. The molecular formula of benzene is originally C6H6, but when expressed per mole of carbon, it becomes CH, as shown in the "complete combustion stoichiometric formula" in Figure 1. Based on this stoichiometric formula, the standard enthalpy of formation of oxygen is "0", so the balance equation for the complete combustion reaction can be expressed by equation (1) in Figure 1. Then, by rearranging equation (1), we can obtain the "standard enthalpy of formation per mole of carbon" for benzene.
[0019]
number
[0020] This can be expressed by equation (2) in Figure 1. That is, the enthalpy of formation of benzene is [1] Higher heating of benzene per mole of carbon
[0021]
number
[0022] If it is known, [2] Standard enthalpy of carbon dioxide production
[0023]
number
[0024] [3] Standard enthalpy of water
[0025]
number
[0026] It can be uniquely determined using [this method].
[0027] Similarly, for polymer compounds, if the heat of complete combustion is known, then the values of [2] and [3] are also known, making it possible to determine the "standard enthalpy of formation per mole of carbon".
[0028] In the example of benzene (equation (2) in Figure 1), the coefficient of the enthalpy of water formation is "1 / 2," but in the case of polymer compounds, this coefficient changes depending on the type of polymer compound. For example, if the molecular formula per mole of carbon in a certain polymer compound is CH m O l When expressed as such, the coefficient of the enthalpy of water formation is "m / 2".
[0029] Standard enthalpy of formation is defined as the energy required to decompose a polymer into its basic constituent elements (C, H2, O2, N2, S) under standard conditions (where the standard enthalpy of formation is zero). Therefore, the standard enthalpy of formation calculated by equation (2) can be considered as the "pure decomposition heat per mole of carbon (kJ / mol)" of the polymer compound. For reference, using this method, the "standard enthalpy of formation per mole of carbon" calculated from the combustion heat per mole of carbon in benzene (544.5 kJ / mol) is 8.03 kJ / mol. Therefore, converting this to units of the molecular formula C6H6 and multiplying by 6 gives 48.18 kJ / mol. This value roughly matches the literature value of 49.0 kJ / mol for the standard enthalpy of formation of benzene.
[0030] <Method for calculating the "standard enthalpy of formation per mole of carbon" for polypropylene> Next, we will take polypropylene (PP) as a specific polymer compound and illustrate how to calculate the standard enthalpy of formation per mole of carbon. Figure 2 shows the molecular structure of polypropylene and how to calculate the standard enthalpy of formation per mole of carbon for polypropylene. The molecular structure of polypropylene is a structure in which many constituent units are linked together, with a basic structure of 3 carbon atoms (C) and 6 hydrogen atoms (H) as one unit (structural unit). Therefore, when rewritten in terms of the molecular structure per mole of carbon, it can be expressed as a stoichiometric formula of 1 carbon atom (C) and 2 hydrogen atoms (H), so the formula for complete combustion is the expression CH2 as shown in Figure 2. Therefore, the heat balance equation for the complete combustion reaction can be expressed by equation (3).
[0031] By manipulating equation (3) in the same manner as shown in Figure 1, the "standard enthalpy of formation per mole of carbon" for the molecular structure of polypropylene can be expressed by equation (4) in Figure 2. According to known data described in "Hideo Oe and Koichi Matsuura: "On the heat of combustion and oxygen index of polymer materials," Research Reports of the Faculty of Engineering, Fukui University, Vol. 23, No. 2, pp. 161-169 (1975)," the total heat of combustion of polypropylene is 11030 kcal / kg. Converting this to kJ, and using the molecular formula CH2, the total heat of combustion per mole of carbon can be calculated.
[0032]
number
[0033] Converted to this, it becomes 646.4 kJ / mol. In this calculation, the atomic weight of C is assumed to be 12 and the atomic weight of H is assumed to be 1. Therefore, this is the heat of complete combustion.
[0034]
number
[0035] Substituting this, along with the known standard enthalpy of formation of carbon dioxide and the standard enthalpy of formation of water, into equation (4), we obtain the "standard enthalpy of formation per mole of carbon".
[0036]
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[0037] Calculating this yields -33.0 kJ / mol. Here, if we want to evaluate the heat of reaction using the standard enthalpy of formation of the molecular structural unit C3H6 shown in Figure 2, rather than per mole of carbon, we can calculate it by multiplying this value by 3 (i.e., -99.0 kJ / mol).
[0038] <Method for calculating the "standard enthalpy of formation per mole of carbon" for polyethylene terephthalate> Next, we will explain the method for calculating the "standard enthalpy of formation per mole of carbon" of PET, the polymer compound covered in this disclosure. Figure 3 shows an example of calculating the standard enthalpy of formation per mole of carbon for PET (polyethylene terephthalate). In the case of PET, oxygen is added to the molecular structure (repeating units), but the basic calculation method is the same as in Figure 2. According to known data described in "Shunsuke Mizukoshi, Takahiro Nakajima, Tomonaga Ueno, Takashi Kajiya, Koshiro Mizuno, Tomoyuki Ishikawa, Shunichi Kondo, Kunihiko Takeda: "Evaluation of the flammability of polymer materials using a new measurement method", Journal of Polymer Science, Vol. 64, No. 11, pp. 765-771 (2007)", the heat of complete combustion of PET is 21600 kJ / kg. Molecular formula CH per mole of carbon 0.8 O 0.4 As such, the heat of complete combustion per mole of carbon
[0039]
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[0040] Converted to this, it becomes 414.7 kJ / mol. At this time, the atomic weight of C is assumed to be 12, the atomic weight of H is 1, and the atomic weight of O is 16. Therefore, this is the heat of complete combustion.
[0041]
number
[0042] Substituting this, along with the known standard enthalpy of formation of carbon dioxide and the standard enthalpy of formation of water, into equation (6), we obtain the "standard enthalpy of formation per mole of carbon".
[0043]
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[0044] Calculating this gives a value of -93.2 kJ / mol. Therefore, the molecular structure of PET (molecular formula C) in Figure 3 is... 10 The standard enthalpy of formation per H8O4 unit is 10 times higher, at -932 kJ / mol.
[0045] Table 1 summarizes the results obtained by determining the "molecular structure unit (repeating unit) and standard enthalpy of formation per mole of carbon" for PE, PP, and PET using the methods described above.
[0046] [Table 1]
[0047] Table 2 also shows, for reference, the "standard enthalpy of formation" of several monomolecule compounds. These values were basically taken from the NIST (National Institute of Standards and Technology) physical property tables.
[0048] [Table 2]
[0049] [Evaluation of endothermic and exothermic reactions in PET chemical reactions] Using the "standard enthalpy of formation" calculated by the methods described above, we will now present a method for evaluating the endothermic and exothermic effects of a reaction. Heat of reaction in a certain reaction equation
[0050]
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[0051] The estimation formula, expressed in common notation, is as shown in equation (7).
[0052]
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[0053] Here, the first term on the right-hand side is the sum of the enthalpies of formation of the products on the right-hand side of the stoichiometric equation, and the second term on the right-hand side is the sum of the enthalpies of formation of the reactants on the left-hand side of the stoichiometric equation. i and α i These are coefficients applied to substance i on the product side and reactant side, respectively, when expressed in stoichiometric formulas. (Third term on the right-hand side)
[0054]
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[0055] This term considers the phase change heat effect when a product, which is solid or liquid under standard conditions, sublimes or evaporates. It is considered positive when a phase change occurs. The third term on the right-hand side is enclosed in double parentheses to indicate that it may or may not be considered. Heat of reaction
[0056]
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[0057] If the value is positive, it indicates an endothermic reaction; if it is negative, it indicates an exothermic reaction. Furthermore, its absolute value represents the amount of heat [kJ / mol].
[0058] In the case of PET, the "standard enthalpy of formation per mole of carbon" can be calculated using equation (6) in Figure 3. However, due to the complexity of the polymer structure of PET, it is difficult to evaluate the reaction products when PET reacts using the "per mole of carbon" method. Rather, it is easier to visually consider the "standard enthalpy of formation per molecular structure unit (repeating unit)." For example, an example of a stoichiometric formula per molecular structure unit for the thermal decomposition of PET is shown in Figure 4.
[0059] Here, since thermal decomposition of PET alone is not complete, we assume that the reaction proceeds with a reactant equivalent to hydrogen gas at standard conditions. For example, we assume that PET is thermally decomposed in the presence of other waste plastics such as PE and PP (under conditions of high-temperature kneading with mechanical load), and that hydrogen is supplied from these polymer compounds (waste plastics) other than PET. According to the literature (NIST), the standard enthalpy of formation of terephthalate ester, the product in this stoichiometric equation, is -733 kJ / mol. Therefore, the heat of reaction shown in Figure 4 can be calculated from equation (7). At this time, terephthalate ester is a solid at standard conditions, but at the high temperature at which thermal decomposition occurs, it is gasified. Therefore,
[0060]
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[0061] Therefore, the heat of sublimation must be considered, which, according to the literature (NIST), is 105 kJ / mol. That is, the heat of PET thermal decomposition reaction shown in Figure 4.
[0062]
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[0063] It can be estimated that this is an endothermic reaction with a reaction rate of -733 + 932 + 105 = 304 kJ / mol.
[0064] On the other hand, in the case of the thermal decomposition of PET, various reaction patterns are possible, not just the reaction shown in Figure 4. It is also possible to consider multiple reaction patterns for the chemical reaction of PET and estimate the endothermic and exothermic amounts for each reaction pattern. Random cleavage of the PET main chain can produce products such as terephthalic acid, CO2, vinylbenzene, acetylene, ethylene, acetaldehyde, benzene, and vinyl benzoate. It is not practical to consider all reaction patterns to account for all such products. Therefore, we will select and evaluate several representative reaction patterns.
[0065] Figure 5 shows possible reaction patterns for PET pyrolysis. The solid, liquid, and gas indications represent the phases under standard conditions. The products vary depending on the cleavage site of the PET main chain, but the combination of products selected is one that fits into a stoichiometric formula, thus representing an idealized reaction pattern. All four reaction patterns (reactions (1) to (4)) commonly require a hydrogen supply. However, since it is unlikely that pure hydrogen gas exists in waste plastics, it can be assumed that the hydrogen is actually supplied from hydrogen bound to other plastic materials besides PET. Therefore, although the heat generated when hydrogen is released from other plastics should ideally be considered, considering the heat generated by such reactions would be extremely complex, so we assume that it can be substituted with hydrogen gas. In addition to these four reaction patterns, other combinations are possible, such as a pattern in which ethylene remains on the benzene ring as a vinyl group. However, we will consider these four reaction patterns as representative examples.
[0066] Reaction (1) in Figure 5 is the same as in Figure 4. For the other reaction patterns, the standard enthalpy of formation of molecular constituent units below the repeating unit and the standard enthalpy of formation of molecular constituent units can be estimated stoichiometrically using known data on the heat of complete combustion, and based on these estimates, the amount of heat absorbed or released in the chemical reaction of PET for each reaction pattern can be estimated. That is, for reactions (2) to (4), similar to reaction (1), the heat of PET pyrolysis reaction can be calculated using equation (7).
[0067]
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[0068] It is possible to estimate this. In this case, assuming a thermal decomposition reaction at high temperatures,
[0069]
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[0070] For this purpose, we consider the heat of sublimation of terephthalic acid (solid at standard conditions) at 142 kJ / mol, the heat of sublimation of benzoic acid (solid at standard conditions) at 90 kJ / mol, and the heat of vaporization of benzene (liquid at standard conditions) at 31 kJ / mol. These transformation heats can also be taken from literature (NIST).
[0071] Table 3 shows the heat of thermal decomposition reaction in four reaction patterns, derived from equation (7).
[0072]
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[0073] The results of the calculations are shown. Since all the calculation results are of the same order of magnitude and are positive, it can be concluded that the PET thermal decomposition reaction is an endothermic reaction.
[0074] [Table 3]
[0075] As mentioned earlier, the composition of products in the PET thermal decomposition reaction is complex. It is difficult to predict in advance which decomposition reactions will primarily occur and what the resulting product composition will be. Therefore, it is preferable to experimentally investigate the relationship between thermal decomposition conditions (such as thermal decomposition temperature) and the product ratio in advance through individual tests, and then adjust the combination ratio of reaction patterns that best reproduces the product ratio based on that product ratio. Once the combination ratio of reaction patterns is known, the endothermic and heat-generating amounts for each of those reaction patterns can be determined, and by weighting them considering the combination ratio, an appropriate endothermic and heat-generating amount can be determined.
[0076] On the other hand, as shown in Table 3, there is little difference between the reaction patterns, and they all fall within the range of 297 ± 20 kJ / mol. Even if other reaction patterns are considered, it is unlikely that the values will deviate significantly from this average. Therefore, it can be expected that simply averaging the heat of pyrolysis reaction for these reaction patterns will not cause any major problems when used as the heat of pyrolysis reaction for PET. In this case, the heat of pyrolysis reaction
[0077]
number
[0078] It can be determined as follows.
[0079] This disclosure makes it possible to estimate the heat of chemical reaction of PET. For example, when configuring a process for thermal decomposition of used PET, the heat of thermal decomposition of PET can be estimated using the estimation method of this disclosure, and an appropriate thermal decomposition process specification can be determined to perform the thermal decomposition of PET. [Examples]
[0080] The following describes examples of the method for estimating the heat of chemical reaction of PET according to this disclosure. However, the method for estimating the heat of chemical reaction of PET according to this disclosure is not limited in any way to the examples described below.
[0081] [Determining the heating capacity to be applied to the PET pyrolysis reaction] <Method> We will design a process to thermally decompose PET contained in waste plastics while heating and kneading them. In other words, we will evaluate the amount of heating required to advance the PET thermal decomposition reaction, assuming the reaction pattern shown in Figure 5.
[0082] As mentioned above, the average PET pyrolysis reaction is,
[0083]
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[0084] This is an endothermic reaction. If the processing rate of waste plastic is W [kg / s], then the heat of PET pyrolysis
[0085]
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[0086] This can be expressed by equation (8) below.
[0087]
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[0088] Here,
[0089]
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[0090] This is the endothermic amount [kJ / mol] of PET pyrolysis, MW PETis the molecular weight per unit (repeating unit) of PET (=192), r PET is the mass ratio of thermally decomposed PET among all the waste plastics to be disposed of. The required waste plastic treatment rate is W = 3 to 4 t / hr = 0.83 to 1.11 kg / s, r PET = 0.15. Substituting these values into equation (8), the heat of PET thermal decomposition
[0091]
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[0092] is evaluated as
[0093]
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[0094] results in the heat absorption amount.
[0095] <Result> In this PET thermal decomposition process, it is necessary to raise the temperature up to 300°C. Therefore, in addition to the heat effect [kW] to be added as the heating capacity such as the moisture content, sensible heat, and latent heat of fusion of the waste plastics, by adding the heat effect of the estimated value of the heat of PET thermal decomposition
[0096]
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[0097] it is possible to perform an appropriate process design.
Claims
1. Representing polyethylene terephthalate in units of molecular components smaller than the repeating unit, The standard enthalpy of formation of the aforementioned molecular constituent units is estimated stoichiometrically using known data on the heat of complete combustion, and Based on the estimated standard enthalpy of formation of the aforementioned molecular constituent units, the amount of endothermic and exothermic reactions of the polyethylene terephthalate is estimated. A method for estimating the heat of chemical reaction of polyethylene terephthalate containing [a specific substance].
2. Multiple reaction patterns for the chemical reaction of polyethylene terephthalate are assumed, and the amount of heat absorbed or exothermic for each reaction pattern is estimated using the estimation method described in claim 1. To measure the production ratio of reaction products generated by the chemical reaction of polyethylene terephthalate. The combination ratio of the reaction pattern is determined based on the measured production ratio of the reaction product, and The amount of endothermic and exothermic reactions of polyethylene terephthalate is estimated by weighting the amount of endothermic and exothermic reactions of each reaction pattern, taking into account the combination ratio. A method for estimating the heat of chemical reaction of polyethylene terephthalate according to claim 1, including the following:
3. Multiple reaction patterns for the chemical reaction of polyethylene terephthalate are assumed, and the amount of heat absorbed or exothermic for each reaction pattern is estimated using the estimation method described in claim 1. To measure the production ratio of reaction products generated by the chemical reaction of polyethylene terephthalate. The combination ratio of the reaction pattern is determined based on the measured production ratio of the reaction product, and By simply averaging the endothermic and exothermic amounts of each reaction pattern, the endothermic and exothermic amounts of the chemical reaction of polyethylene terephthalate can be estimated. A method for estimating the heat of chemical reaction of polyethylene terephthalate according to claim 1, including the following:
4. To estimate the heat of reaction in the thermal decomposition treatment of polyethylene terephthalate by the method for evaluating the heat of chemical reaction of polyethylene terephthalate according to any one of claims 1 to 3, Based on the estimated heat of reaction, the specifications for the thermal decomposition process of polyethylene terephthalate are determined, and The thermal decomposition treatment of polyethylene terephthalate is carried out according to the determined thermal decomposition process specifications. A method for thermal decomposition treatment of polyethylene terephthalate containing [a specific substance].