The influence of equilibrium FCC catalyst amount on the thermolysis

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The influence of equilibrium FCC catalyst amount on the thermolysis process of various polyolefin plastic wastes in the fixed-bed reactor for gasoline and diesel production Egle Valanciene, Linas Miknius, Vytas Martynaitis, and Nerijus Striugas Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b01472 • Publication Date (Web): 05 Sep 2017 Downloaded from http://pubs.acs.org on September 10, 2017

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The influence of equilibrium FCC catalyst amount on the thermolysis process of various polyolefin plastic wastes in the fixed-bed reactor for gasoline and diesel production Egle Valancienea*, Linas Mikniusa, Vytas Martynaitisa, Nerijus Striugasb a

Department of Organic Chemistry, Kaunas University of Technology, Radvilenu pl. 19, 50254

Kaunas, Lithuania b

Laboratory of combustion processes, Lithuanian Energy Institute, Breslaujos str. 3, 44403

Kaunas, Lithuania

Corresponding author: Egle Valanciene, Department of Organic Chemistry, Kaunas University of Technology, Radvilenu pl. 19, 50254 Kaunas, Lithuania; e-mail [email protected], tel. +370 634 40249

ABSTRACT The comprehensive study of waste industrial and automotive plastics (polypropylene (PP), polyethylene (PE), polystyrene (PS), ethylene-propylene co-polymer (E/P), thermoplastic elastomer based on the ethylene–propylene–diene terpolymer and polypropylene (PP/EPDM)) thermolysis processes with 0%, 10% and 25% of equilibrium fluid catalytic cracking (FCC) catalyst content were investigated and the catalyst suitability for the thermolysis process was evaluated. The experiments were carried out in the fixed-bed reactor. Reaction time and product

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yields depend on the ratio of a catalyst and a feedstock. The catalyst used leads to the formation of branched C7-C9 hydrocarbons as the main products as well as to the increased content of aromatic compounds. According to the liquid products composition, it was determined that catalyst acidity is excellent only for PE thermolysis and the products obtained from this raw material are liquid only in case of catalytic thermolysis. Aromatization indexes, competitive parameter, the relative amounts of aromatization and isomerization reactions and the ratio of unsaturated and saturated hydrocarbons were estimated for nonaromatic raw materials to evaluate mechanistic pathways of processes. It was determined that catalytic reactions mainly occur at the lower temperature and they run via a free radical mechanism as the reaction temperature increases. The kinetic and thermodynamic parameters were also estimated for all raw materials using thermogravimetric data which appeared dependent on the catalyst/polymer ratio and the plastic type used. The appropriate amount of catalyst for each raw material was determined for the production of diesel and gasoline cuts.

Keywords: Thermolysis, equilibrium FCC catalyst, plastic waste, industrial waste, automotive waste, kinetic parameters, thermal analysis, diesel, gasoline

1. INTRODUCTION Polyolefins are widely used for the production of various items – packages, toys, vehicle parts, construction materials and in other fields because of the outstanding properties of these plastics. In 2013, the production volume of plastics was almost 300 million tons, and it is expected to reach 400 and 700 million tons by 2020 and 2050, respectively [1], which leads to the increased amount of plastic waste. Disposal of cars and light commercial vehicles 2 ACS Paragon Plus Environment

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at the end of their operational lives generated over 14 million tons in 2015 [2]. Recycling scrapped cars plays an important role in reducing pollution by decreasing the amount of waste that ends up in landfills [2]. The most of industrial plastic waste (including cars parts as automotive waste) have relatively good physical characteristics i.e. they are sufficiently clean and free of contamination and are available in fairly large quantities [3]. Plastic wastes can be mechanically or chemically recycled, used in power generation (incinerated), and disposed of in the landfills (this option is the least favorable). In chemical recycling, advanced thermochemical treatment methods cover a wide range of technologies and may produce either fuels or petrochemical feedstock [4]. Nowadays, thermal cracking (thermolysis) is receiving renewed attention, due to the fact of added value on a crude oil barrel and its very valuable yielded products, but advanced thermo-chemical recycling of polyolefins still lacks the proper design and kinetic background to target certain desired products and/or chemicals [5]. A high temperature for thermolysis is required in order to crack the polymer molecules and subsequent products. Catalytic thermolysis is an alternative to the recycling of various plastic wastes using a lower temperature in reactors. The catalyst can promote [6, 7]: •

decomposition reactions at low temperatures with lower energy consumption;

•

reduced production costs;

•

increase the yield of products with a higher added value;

•

increase the process selectivity;

•

faster cracking reactions, leading to smaller residence times and reactors with smaller volumes;

•

inhibiting the formation of undesirable products;

•

obtain liquid products with a lower boiling point.


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For aforementioned reasons the appropriate polymer/catalyst ratio is required for each type of raw material. In the previous study we have investigated the influence of equilibrium FCC catalyst amount to the kinetic and thermodynamic parameters of polypropylene thermolysis reactions [8]. The variation of these parameters with different amount of catalyst resulted in the different product distributions of the plastic thermolysis. For this reason the experiments within the reactor were performed using 5 types of plastic (automotive and industrial) wastes and different amounts of equilibrium FCC catalyst. The main goal of this paper is to draw complete conclusions about catalytic thermal cracking process of plastics: the influence of different amount of catalyst to the thermolysis reactions for various types of plastic waste, the distribution of their product yields and composition, process conditions, and the determination of the influence of FCC polymer/catalyst ratio to the kinetic and thermodynamic parameters and aromatization reaction of the plastic thermolysis. The obtained results help to choose the appropriate amount of a catalyst for diesel or gasoline fractions production from various types of scrap plastics because the activity and selectivity in the catalytic cracking of polymers largely depend on the chosen catalyst, and the factors such as pore size or acidity wield a decisive influence upon its performance [9]. These results are important for process characterization and modelling of the thermolysis plant as well as for the practical application of the catalyst in the chosen plastic waste thermolysis for fuel production. From the economic point of view the cost of a catalytic system is estimated based on used FCC catalyst which is comparable to that of a commercial thermal cracking plant, because spent FCC catalyst still maintain enough activity to be considered as a good choice owing to the fact that its cost is basically zero and it is continuously being disposed of from FCC units [10].


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2. MATERIALS AND METHODS Various types of plastic waste were used: polypropylene (PP), polyethylene (PE), polystyrene (PS), ethylene-propylene co-polymer (E/P), thermoplastic elastomer based on the ethylene–propylene–diene terpolymer and polypropylene (PP/EPDM). PP, PE and PS were collected as industrial waste. E/P and PP/EPDM were collected from the local dump of car parts. All raw materials were crushed into pieces (the particle size was ≤20 mm). Zeolite regenerated NaceR™ FCC (“Grace”, USA) catalyst was received from PC “ORLEN Lietuva” refinery. The properties of raw materials used are presented in the Tables 1 and 2. Amounts of the catalyst in the mixtures with plastics were 0, 10 and 25 percents. 2.1. Thermogravimetric experiments and calculation of kinetic and thermodynamic parameters. Thermogravimetry experiments were carried out with the thermogravimeter TGA 4000 (Perkin Elmer, USA) at an inert atmosphere at a temperature in the range of 303-823 K. Calibration of TGA apparatus was performed with three standard reference materials (alumel, perkalloy and iron) up to 1173 K. Nitrogen gas flow rate was set to 20 ml/min. The plastics samples were grounded to pieces and mixed with the appropriate amount of a catalyst mechanically before each experiment. Samples were loaded without compacting into an open ceramic crucible. The thermogravimetric experiments were repeated while R2 values of the plots used for activation energy estimation at each conversion for all mixtures were more than 0.97. The amount of plastic used in the single experiment with TGA apparatus was 3±1 mg as it is required by the standard method [11] for obtaining the exact value of pre-exponential factor, when sample is heated at different heating rates [12]. According to [13], the value of the calculated activation energy is only independent of the reaction order in the early stages of decomposition reaction. Because impurities can affect the results at lower conversions, the 5 ACS Paragon Plus Environment

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standard method [11] for conversions of 0.1 (Eq. 1) was applied. Activation energies were also estimated at the Tp temperature using the Flynn-Wall method (Eq. 2) [14]:

E = − ∙ ∆(log β⁄∆ logβ = log

(

− 2.315 − 0.4567

(1)

(2)

where b is an approximation derivative which is equal to 0.457 K on the first iteration. Afterward, when calculating Ei-1/RT values, a new b estimation was chosen. By substituting this value of b to the previous equation, the value of Ei was estimated. The procedure was repeated until the activation energy change was less than 1 %. Using the Flynn-Wall method, the Ea value is calculated from the slope of logβ vs 1/T for the given mechanism function G(α). The advantage of this method is that the activation energy is directly calculated without using the mechanism functions which would result in errors. The Flynn–Wall method can be used for the wider range of degree of mass conversion and make no assumption about the order of reaction in calculation of activation energy [15]. The estimated maximum RSD values for the activation energy estimated by both methods did not exceed 1 %. The pre-exponential factors (A) and thermodynamic parameters such as the changes of enthalpies (∆H≠), Gibbs free energies (∆G≠) or entropies (∆S≠) were calculated by following Eqs. 3-6 [14] at the Tp temperatures: *

! = " ∙ #$ ∙ %&' ),∙-+ /601 ∙ 234 5

(3)

.

∆7 8 = #$ − 12

(4)


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=> ∙-.

∆9 8 = #$ + 1 ∙ 23 ∙ ;< ∆A 8 =

?∙@

∆B C D∆E C -.

(5)

(6)

where KB is the Boltzmann constant, and h is the Plank constant, Tp is the peak temperature. According to ASTM E 1641 standard, the pre-exponential factor is estimated by the following equation [11]: F

! = − * ∙ 1 ∙ ;< (1 − G ∙ 10$

(7)

where a is an approximation integral. 2.2 Experiments within a reactor. Thermolysis experiments were carried out in the fixedbed reactor. The reactor flowsheet is shown in the Fig.1. A 3 dm3 reactor was loaded with the appropriate amount of feedstock (the load mass did not exceed 1kg) and catalyst (the catalyst concentration was 0%, 10% and 25%), purged with nitrogen, hermetically closed with a lid and heated by an electrical muffle furnace, raising the temperature from an ambient temperature to 773 K. The degradation process was carried out at an atmospheric pressure. Throughout the process, the furnace was transferring heat to the reactor at a constant 3 kW power. During the plastics thermolysis processes, the gaseous and liquid products were separated in a separator. The fractions of thermolysis oil were accumulated in the separator for 250±5 ml of each fraction. The liquid product fractions were collected via the separator: the valve of the separator was opened when it was loaded with 250 ml of liquid. Four fractions were collected for each experiment with some exceptions: only 3 fractions were collected for PP, PP/EPDM and PE thermolysis and for 90% PS+10% FCC catalyst and 75% PP/EPDM+25% FCC catalyst 7 ACS Paragon Plus Environment

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thermolysis. Noncondensable thermolysis components flowed through the gas meter to the torch. The solid-phase product remained in the reactor, which was collected when the system was cooled. During the thermolysis process, the pressure and temperature were recorded with the valve (Fig. 1, position 5) opened. The process was terminated when the gas ceased to flow from the reactor and the temperature inside it reached 773 K. 2.3 Estimation of product yields The yields of thermolysis products were estimated as the mass ratio of each product and raw material. Firstly, the liquid and solid product masses were determined and the mass of gas was estimated as a difference of masses of raw material and other products. The uncertainty of the product yields was estimated by repeating the experiments with 25% of FCC catalyst for all materials, because our experience reveals: the higher amount of catalyst, the bigger uncertainty is obtained. The estimated maximum RSD are 1.2% (for gas), 1.6% (for liquid), 3.7% (for solid). 2.4 Coke yield The coke yield was determined as an average of the results of two experiments. The 1 g of sample material was heated in the electric furnace in the air atmosphere at a temperature of 823±1 K for 4.5 hours. The coke yield was estimated as the ratio of mass loss and the initial polymer solid thermolysis product weight. The estimated maximum RSD for this experiment did not exceed 3.4 %. 2.5 Chromatographic analysis. Chromatographic analysis of liquid products was carried out on Shimadzu GCMS-QP2010 Ultra gas chromatograph, equipped with a Rtx-1 PONA capillary fused silica column (100 m × 0.25 mm inner diameter, with a film thickness of 0.5 µm), flame ionization and mass selective detectors, and helium as the carrier gas. The samples of 8 ACS Paragon Plus Environment

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liquid products were dissolved in methanol before chromatographic analysis. The column temperature program was 303 K for 3 min, followed by a 2 K/min heating rate to 473 K, followed by a 3 K/min heating rate to the final temperature of 533K, and held at 533 K for 2 min. The quadrupole mass spectrometer was set at the standard ionizing voltage of 70 eV with a mass range of m/z 40−500 and a scan speed of 2500 amu/s. The identification of the compounds was accomplished using a library search in a National Institute of Standards and Technology (NIST) database in combination with evaluation of the mass fragmentation pattern. Quantitative analyses were derived from the results of qualitative analysis; that is, all the chromatograms of samples were integrated under equal conditions, and the percentage amounts of the components were calculated according to the peak areas. The results presented are the mean of the two measurements. The maximum estimated RSD value did not exceed 3.1%. 2.6 The estimation of specific indexes of thermolysis reaction. The aromatization index (AI), competitive parameter (CP), the comparative/relative amounts of aromatization and isomerization reactions (Xa and Xi, respectively) were estimated according to the chemical composition of liquid products for all fractions of thermolysis products of all primary materials and mixtures. The formulas for gasoline catalytic cracking [16] were applied for evaluation of catalytic and thermal process of plastic thermolysis. The ratio of unsaturated hydrocarbons (olefins) and saturated hydrocarbons (paraffins) O/P was estimated as well. Below the formulas (Eqs. 8-12) for estimation of aforementioned parameters are presented: AI = (The amount of aromatic hydrocarbons) / (The amount of unsaturated hydrocarbons) (8)


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CP = (The amount of aromatic hydrocarbons) / (The amount of branched saturated hydrocarbons)

(9)

Xa = (The amount of aromatic hydrocarbons) / (The amount of branched and aromatic hydrocarbons)

(10)

Xi = (The amount of branched hydrocarbons) / (The amount of branched and aromatic hydrocarbons)

(11)

O/P = (The amount of unsaturated hydrocarbons) / (The amount of saturated hydrocarbons) (12) 2.7 The yields of gasoline and diesel cuts. For the correct evaluation on the FCC catalyst amount on the production of gasoline and diesel cuts, the obtained liquid fractions as thermolysis products were separated. The hydrocarbon mixtures with boiling points up to 473 K were collected as a gasoline fraction, and the mixtures with boiling points range of 473-623 K were collected as diesel fraction. The average mass of each fuel fraction for all materials and their mixtures with FCC catalyst was determined and the yields were estimated. The results presented are the mean of the measurements of the yields of each fraction obtained. The maximum estimated RSD value did not exceed 5.7 %. 3. RESULTS AND DISCUSSION The thermal and catalytic thermolysis was carried out in the fixed-bed reactor for the various types of plastic waste such as PE, PP/EPDM, PP, PS, E/P. The thermolysis reactions of plastics occur via the free radical mechanism and the instability of 10 ACS Paragon Plus Environment

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macromolecules is often caused by the presence of the anomalous weak chemical bonds in the polymer [17]. Catalytic thermolysis proceeds through carbenium ions which are initiated by the abstraction of hydride ion from the polymer macromolecule when a catalyst acts as Lewis acid. The following stages proceed both by thermal and thermocatalytic paths [17]: chain propagation (cleavage to gaseous and liquid products, intermolecular hydrogen transfer, isomerization, coke formation etc.) and chain termination by disproportionation or recombination of radicals. The influence of FCC catalyst amount to the thermolysis reactions, mechanisms, process conditions, the yields of products, chemical composition of liquid products were determined by conducting the processes in the fixed-bed reactor. The influence of catalyst amount to the values of thermodynamic and kinetic parameters was determined applying thermogravimetric analysis. The catalyst amount is also important for the production of diesel and gasoline fractions. All these aspects of thermal and catalytic reactions are discussed below.

3.1 The results of chromatographic analysis of liquid products 3.1.1 PE thermolysis. During thermolysis (without FCC catalyst) the amount of unsaturated compounds ranges between ~55 and ~58% in all fractions (Table 3). Linear compounds predominate among both saturated and unsaturated hydrocarbons and their amount in each fraction decreases from 39.7 to 34.6% (for saturated hydrocarbons) and from 45.5 to 46.6% (for unsaturated hydrocarbons). The total amount of branched hydrocarbons increases up to ~7.5% during the reaction. The derivatives of benzene are produced mostly in the beginning of the reaction (~3%), and their amount in the last fraction is only ~1%. Cyclic 11 ACS Paragon Plus Environment

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unsaturated compounds are produced mainly in the beginning of the reaction and at the end of the process (~6% for 1st and for 3rd fractions). Saturated cyclic compounds reach the highest concentration in the 2nd and 3rd fractions and their amount in both fractions is about 4.2%. The major products of thermolysis in the 1st fraction are C7-C15 hydrocarbons. In the other fractions (2nd and 3rd ones) the amount of C10-C15 compounds is continually decreasing, however, the amount of C7-C9 compounds is constantly increasing. During thermolysis the C-C bonds cleave at the random locations as a result the linear structure of different molecular mass compounds are predominant. When those products stay in the reaction zone for a longer time, the isomerization reactions can occur and the amount of branched hydrocarbons increases (the 2nd and later fraction). Chain termination reactions occur via radicals bimolecular coupling and disproportionation. Cyclic and branched compounds can be produced during the reaction at the higher temperature due to the radical coupling. Aromatic compounds are produced at the higher temperature during the secondary cracking reactions. The temperature during entire complex thermochemical process is not constant, therefore various types of products do not keep the even change in their amounts. At the higher temperature cyclization and aromatization reactions occur easier because they are endothermic thus those reactions absorb the energy from the reaction mixture which results in decreased temperature in the system. The decreased temperature slows down the rate of aforementioned endothermic reactions. Adding the catalyst into the reaction mixture leads to the significant increase of the amount of aromatic and branched compounds and to the decrease of the amount of cyclic compounds (Table 3). In each fraction the amount of cyclic compounds is ~ 1.5% (for mixtures with 10% of FCC catalyst) and in the range of ~1.3-4.2% (for mixtures with 25% of


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FCC catalyst). Using the 25% of FCC catalyst the largest amount of aromatic compounds is observed at the end of the reaction, because aromatization reactions take place in the smallest pores of the catalyst and these products are withheld for a longest time [10]. The amount of linear compounds is in the range of ~18-27% (for catalytic thermolysis) independently on the catalyst fraction. The amount of unsaturated hydrocarbons (in the catalytic process) slightly increases so the acidity of the FCC catalyst appears appropriate for the thermolysis of PE. When the catalyst is added into the reaction mixture, C7-C12 compounds are predominant in the liquid products of PE thermolysis. During termination reactions the higher molecular compounds may be formed, therefore, the concentration of C16-C20 hydrocarbons is up to 1.0% and up to 3.4% for catalytic and noncatalytic processes, respectively. In the noncatalytic process the largest amount of C16-C20 hydrocarbons is in the 1st fraction and later they can be cracked into the smaller molecules when they stay in the reaction zone for a longer time. For the catalytic thermolysis process the higher hydrocarbons (C16-C20) are formed in the beginning of the reaction due to the short reaction time and later due to the possible polymerization reactions. 3.1.2 PP/EPDM thermolysis. The thermal degradation temperature for PP/EPDM is close to pure EPDM thermal degradation temperature (~443 K) and the main thermolysis products (for the 1st fraction) are the products of EPDM thermal degradation (e.g. aromatic compounds). During thermolysis the amount of unsaturated compounds varies in the range of ~78.0-88.5 % for all fractions and their amount decreases during the reaction (Table 4). The branched hydrocarbons are predominant among saturated and unsaturated compounds which comprise ~5-11% and ~65-72.6%, respectively. The total amount of linear


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compounds increases from 5% to 10.5% during the reaction. Aromatic compounds mainly obtained in the beginning of the reaction (~17% for the 1st fraction), and in the other fractions amount of arenes is in the range of 1.5-2.7%. The amount of cyclic compounds increases from 5.2% to 8.5%. In the 1st fraction aromatic and cyclic compounds generally are formed as the primary products of EPDM decomposition. The main products of PE thermolysis for the 1st and the 2nd fractions are C7-C9 hydrocarbons (>70 %), and for the other fractions the concentration of C7-C9 and C10-C12 compounds increase up to ~45 and ~49 %, respectively, due to the formation of trimers and tetramers of propylene. Adding the catalyst to the reaction mixture leads to the formation of C7-C9 hydrocarbons as the main products (Table 4). The catalyst changes the amount of saturated and unsaturated compounds as well. The highest concentration of saturated hydrocarbons is in the 1st fraction (~19%) and in the other fractions it is in the range of 13.9-15.4 % when the catalyst fraction is 10%. Usage 25% of catalyst results in the considerable formation of saturated hydrocarbons (~28-32.6%). The amount of branched compounds in all fractions falls in the range of ~65-70% either for thermal and catalytic thermolysis products, which is caused by the branched structure of the primary material. The concentration of linear compounds is higher for the thermocatalytic process and it is independent from the catalyst amount used. In the beginning of the reaction (for the 1st fraction) the amount of linear compounds is rather similar ~13 and 15% of it for 10 and 25% of FCC catalyst, respectively, and later the amount of those compounds is rather constant for the mixtures with 25% FCC catalyst. For mixtures with 10% FCC catalyst the concentration of linear compounds increases up to ~20%. For thermolysis of mixtures with 10% FCC catalyst in the 3rd fraction, the main products are C5-C6 hydrocarbons (~26.5 %) because the reaction temperature is


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close to the noncatalytic process temperature at the same time and this results in possibility for radical reactions to occur. Using 25% FCC catalyst the amount of C5-C6 hydrocarbons is ~15-20% due to the overcracking. The amount of aromatic compounds increases during the reaction when catalyst concentration is 25%. Then the reaction temperature is too low for rapid degradation of EPDM and all components of the raw material can degrade gradually. Besides, when the some primary degradation products are adsorbed heavily on the catalyst, the aromatization reactions may occur [10] and the final products enriched by arenes are removed from the reaction zone at the latest as the final fraction (in contrast to solely thermolysis process). The total amount of cyclic compounds is lower when catalyst is used. When FCC catalyst concentration is 25% then the amount of cyclic compounds decreases during the process as they turn to aromatic compounds, which could participate in coke formation reactions. When FCC catalyst concentration is 10%, at the beginning of the reaction the amount of cyclic compounds decreases and from the 3rd fraction their amount increases due to higher ratio of catalyst to unreacted plastic and therefore the cyclization reactions may occur faster. For thermocatalytic degradation the amounts of unsaturated and branched structure hydrocarbons decrease with increasing FCC catalyst concentration and this proves that the catalyst is too acidic [10] for thermolysis of PP/EPDM.

3.1.3 PP thermolysis. For PP thermolysis in all fractions, the amount of unsaturated compounds is continually decreasing during the reaction and it is in the range of ~76.5-82 % (Table 5). The saturated and unsaturated hydrocarbons are mostly obtained as branched compounds due to the chemical structure of primary material. The concentration of the


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branched compounds is 8.7-9.9% (for saturated hydrocarbons) and 62.3-79.5% (for unsaturated hydrocarbons). The total amount of linear compounds increase from ~4.5 to 19.5 % during the reaction because the isomerization reactions occur at the higher temperature. The concentrations of obtained saturated and unsaturated linear compounds are rather similar in the same fraction. The amount of cyclic hydrocarbons increases from ~7% to ~10% and among them the saturated ones are prevailing. The aromatic compounds were not obtained in any fraction of PP thermolysis. The main products of PP thermolysis are C7C9 compounds (>69 %) and their amount during the reaction continually decreases therefore the amount of C5-C6 and C10-C12 compounds increases (which is mostly the isomers of dimers and trimers of propylene). During thermal degradation of C7 and higher hydrocarbons, more C5-C6 hydrocarbons can be obtained and due to the radical coupling reactions the heavier hydrocarbons (C10-C12) may be formed. Adding the catalyst to the system leads to the formation of C7-C9 hydrocarbons as the main products. For each fraction of FCC catalyst+PP mixtures the concentration of unsaturated hydrocarbons decreases with increasing FCC catalyst amount. For PP thermolysis this tendency exists only in the 1st fraction, and later the amount of unsaturated compounds is a little bit lower than that for the mixture with 10% FCC catalyst. For all PP and FCC catalyst mixtures, the total amount of unsaturated hydrocarbons shows uneven changes during the reaction (it can increase or decrease). The same change is observed for the aromatic compounds. When aromatization/cyclization/isomerization reactions absorb the energy of the reaction mixture, the temperature in the reactor decreases and those reactions proceed slower thus the yields of appropriate products are lower. For both thermocatalytic processes the amount of linear compounds is ~16%.


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The catalyst used is too acidic [10] because the yields of unsaturated and branched hydrocarbons decrease with increasing FCC catalyst amount. Because of the nature of feedstock, branched compounds are the main products. For each mixture with FCC catalyst the amount of aromatic compounds at the end of the process is highest due to the secondary reactions occurring for the trapped primary products in the smallest pores of the catalyst [10]. 3.1.4 E/P termolysis. For E/P thermolysis C7-C9 hydrocarbons are the main products in all fractions (Table 6). The total amount of unsaturated compounds varies in the range of ~71-86% for all fractions and the lowest amount of those compounds is obtained at the end of the process (in the last fraction). Among unsaturated compounds the branched hydrocarbons are predominant (~64.6-81 %). The total amount of linear compounds is up to 6.0%, because the primary material consists of branched and linear fragments formed during polymerization of propylene and ethylene. Aromatic compounds are determined only in the beginning and at the end of the processes in the concentration of ~0.3%. The amounts of formed isomers of propylene trimers and tetramers are ~60% and ~8-27%, respectively, in all fractions. 2,4dimethyl-1-heptene is obtained as the main thermolysis product and its concentration decreases from ~50% (the 1st fraction) to ~40% (the last fraction) as a result of the secondary degradation reactions due to prolonged residence time in the reactor. The main compounds are obtained as C6-C10 hydrocarbons when the catalyst is used and most of them have a branched structure. For catalytic thermolysis the amount of aromatic compounds is ~4%, and at the end of the process it may reach up to ~30% for the mixture with 25% FCC catalyst. This is rather close to the aromatic yield of PP catalytic thermolysis. Independently of the catalyst amount used, the amount of cyclic compounds in all fractions may reach up to 2.7%. The concentrations of unsaturated and branched hydrocarbons


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decrease with increasing FCC catalyst amount and, consequently, the catalyst used is too acidic for this feedstock [10].

3.1.5 PS termolysis. The main reaction for thermolysis of PS is depolymerization which results in ~88-94% of styrene content (Fig.2). β-scission, hydrogen transfer and dehydrogenation reactions occur at the high temperature and that leads to the formation of ethylbenzene, methylstyrene, toluene and other aromatic compounds from PS fragments. The small amounts of aliphatic compounds are also formed when the phenyl ring is split off from the main chain of the macromolecule. When adding the acidic catalyst into the thermolysis reaction of PS, the reaction mainly follows the carbenium ion mechanism. The most likely reaction pathway involves the attachment of proton associated with Bronsted acid site to the aromatic rings of PS due to the reactivity of its side phenyl groups towards electrophilic reagents. The resulting carbenium ion may undergo β-scission followed by a hydrogen transfer [18].These reactions yields benzene, styrene, methylstyrene, toluene and other derivatives. The cross-linking reactions are also possible for protonated polymer macromolecules. Benzene is formed by the further cracking reactions or direct dealkylation of protonated aromatic ring. Ethylbenzene and propylbenzene are produced by intermolecular hydride ion transfer of the intermediates formed by β-scission of C-C bonds in PS. For the competitive pathways for styrene and ethylbenzene formation, the latter seems favorable at lower temperature and the former at a high temperature [18]. As follows, when higher amount of catalyst is used, the thermolysis process may occur at lower temperatures. For this reason the amount of styrene produced decreases with increasing FCC catalyst concentration (Fig. 2) and accordingly the higher


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Energy & Fuels

amounts of toluene, ethylbenzene, benzene are obtained. The amount of α-methylstyrene is higher for thermocatalytic process with lower catalyst amount. When using a larger amount of the catalyst (25% in this case) α-methylstyrene may undergo the further scission, hydrogenation and disproportionation reactions.

3.2 FCC catalyst influence to the thermolysis liquid products and its chemical composition For catalytic thermolysis the catalyst is used for the lower process temperature and for obtaining better yield of branched and aromatic hydrocarbons in the liquid products as it is proved by the gas chromatography data of liquid products of various plastic thermolysis (Fig.3). The catalytic thermolysis products are all liquids. It is important especially for PE thermolysis because the thermolysis product of PE is solid at the room temperature but adding 25% of FCC catalyst to the reaction mixture leads to formation of lower pour point hydrocarbons which appear liquid at the room temperature. The catalyst used leads to the formation of branched C7C9 hydrocarbons where unsaturated hydrocarbons prevail over saturated ones. The aromatic compound concentration is also increased with increasing FCC catalyst fraction which means that the product octane number is also increased [10]. The reduction of C7-C9 hydrocarbons and the increased concentrations of C5-C6 hydrocarbons refer to the overcracking of the products at the active sites of the catalyst also resulting in the increased volume of thermolysis gas. The catalyst also accelerates isomerization, cyclization, hydrogen transfer, aromatization, polymerization reaction [10]. These reactions absorb energy from the surroundings and lead to the decrease of the temperature in the reactor. For PS thermolysis, higher amount of FCC


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catalyst allows to form more aromatic compounds with saturated alkyl side chains and to obtain lower amount of styrene. The proper amount of FCC catalyst is important for gasoline and diesel production. Gasoline consists mostly of C5-C12 hydrocarbons, and the main hydrocarbons of diesel are C11C20. According to the chromatographic data, the amount of gasoline fraction for thermolysis of PP/EPDM, PP, E/P tends to decrease with increasing FCC catalyst concentration in the mixture, but 10% FCC catalyst helps to obtain products that are liquid at the room temperature. For PE thermolysis the gasoline fraction (especially the amount of aromatic and saturated hydrocarbons) is increasing with increasing FCC catalyst concentration. The yield of diesel fraction is decreasing with increasing FCC catalyst amount only for PP/EPDM thermolysis. For PE thermolysis the higher FCC catalyst concentration allows to form more C10-C12 saturated and branched hydrocarbons and to increase the aromatics content in the products. The same tendency also exists for PP thermolysis process. Only for E/P thermolysis C11-C20 fraction yield is marginally increasing with increasing FCC catalyst concentration. As follows, for the production of diesel cut from PP, PE and E/P, the catalyst concentration should be 25%. PS thermolysis products are best for the gasoline production and the 25% of catalyst helps to have the higher concentration of saturated compounds. For the final conclusions on the FCC catalyst amount on the production of diesel or gasoline cut, all the obtained fractions of each raw material liquid thermolysis products were distilled and the average yields from each fraction were determined (Table 7). The catalyst used is important for better yields of gasoline cut and the yields of it may reach 60-70% from each raw material, when catalyst's amount is 25%. For this reason the catalytic thermolysis of PP/EPDM, PE, PP and E/P with 25% FCC catalyst should be applied for a production of gasoline cut. For PS the best yields of a gasoline cut are obtained from the


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Energy & Fuels

process with 10% FCC catalyst. Due to the high aromatic compound content in the thermolysis products, PS is recommended only for a gasoline cut as a good octane number booster. The thermolysis is more favorable for the E/P, PE and PP, when thermolysis products should be used for a diesel cut. For the same purpose, the thermocatalytic process with 10% of FCC catalyst should be applied for PP/EPDM. For all raw materials, the obtained liquid products of thermolysis have to be chemically stabilized before using them for the final preparation of commercial gasoline and diesel. 3.3 FCC catalyst influence on aromatization reaction for nonaromatic feedstocks of thermolysis The ten-lump kinetic model of gasoline [19] can be used in describing the catalytic thermolysis of plastics. The primary products of plastic thermolysis reactions are olefins. According to [19], olefins cyclization reactions, hydrogen transfer and abstraction reactions mainly happen through carbenium ions when the catalyst is used in the process. Aromatic compounds are formed during hydrogen transfer or abstraction reactions mainly from carbenium ions. Paraffins are produced from olefins or carbenium ions via hydrogen transfer. Lighter olefins are obtained during cracking reactions of olefins. Iso-olefins are produced from olefins, and iso-paraffins may also be produced from iso-olefins via hydrogen transfer. C3 and C4 hydrocarbons are the products of iso-paraffins cracking reactions. The aromatization index (AI), competitive parameter (CP), the comparative/relative amounts of aromatization and isomerization reactions (Xa and Xi, respectively) and the O/P ratios were estimated according to the chemical composition of liquid products for all fractions of thermolysis products of all primary materials and mixtures. AI index is pointed out based on


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hydrogen transfer. The CP index represents the distribution of aromatic compounds and isoparaffins (branched hydrocarbons). AI, CP, Xa, Xi indexes allow to better estimate the relative ratio of thermal and catalytic thermolysis reactions occurring in the mixtures with FCC catalyst because carbenium ion mechanism mainly happens in the isomerization reaction, whereas aromatization reactions are based on the free radical mechanism followed by hydrogen transfer reaction. Figs. 4 and 5 show the estimated values of all the aforementioned parameters. These values mostly depend on the feedstock and catalyst amount used. The greater is the AI value, the greater is the aromatization reaction. When the CP value is more than 1.5, the aromatization reaction dominates. When the CP value is less than 0.6, isomerization reaction dominates. When the CP value is between 0.6 and 1.5, the aromatization reaction and the isomerization reaction happen at the same time [16]. As follows, in the beginning of the processes, the isomerization reactions mainly happen in all reaction mixtures, and the aromatization reactions may occur faster with the increase in the reaction temperature. Aromatization reactions and isomerization reactions always occur at the same time for all mixtures and the reactions occurring through carbenium ion play a leading role in the thermolysis processes of PP, PE, E/P and PP/EPDM for this catalyst and experimental conditions. The variations of the aforementioned parameters with varying catalyst amount during the reaction show these tendencies: 1. AI increases with increasing FCC catalyst amount in the mixture (comparing the

same serial number of fraction for each primary material). The higher concentration of catalyst active sites results from the higher amount of catalyst used thus larger number of thermocatalytic degradation reactions may occur, such as hydrogen 22 ACS Paragon Plus Environment

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Energy & Fuels

abstraction or hydrogen transfer. These reactions lead to the formation of more aromatic products. For each primary material or mixture with FCC catalyst AI parameter changes unevenly during the reaction because decreased temperature in the reactor leads to slower aromatization reactions. As follows, the increasing AI value with increased temperature means that the free radical reactions are also taking place at the same time. At a higher temperature and the presence of catalyst, hydrogen transfer and aromatization reactions are also observed [10]. 2. CP increases with increasing FCC catalyst amount in the mixture (comparing the

same serial number of fraction for each primary material). The higher concentration of catalyst active sites results from the higher amount of catalyst used and therefore larger number of hydrogen transfer reactions occur. Hydrogen transfer reactions mostly lead to the aromatic compounds formation but not to the formation of branched structure hydrocarbons. For each primary material or mixture with FCC catalyst CP parameter changes unevenly during the reaction due to the uneven changes of reaction temperature in the reactor. 3. Xa increases and Xi decreases with increasing FCC catalyst amount in the mixture

(comparing the same serial number of fraction for each primary material) because hydrogen transfer and abstraction reactions are more favored (when more catalyst is present) than isomerization reactions. For each primary material or mixture with FCC catalyst Xi and Xa parameters change unevenly during the reaction due to the changes of the reaction temperature in the reactor but their sum is always equal to 1.


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4. O/P decreases with increasing FCC catalyst amount in the mixture (comparing the

same serial number of fraction for each primary material). Olefins are considered to be the primary products of plastic thermolysis and parafins are obtained only during hydrogen transfer reactions [10, 17]. Larger amount of catalyst used results in higher concentration of active sites which allows olefins crack that yields more parafins through hydrogen transfer reactions. For all raw materials and their mixtures with FCC catalyst the estimated parameters have some exceptions due to the reaction conditions and chemical composition of the feedstock. All these exceptions are discussed below. For the PE thermolysis products only in the 1st fraction Xa index decreases and Xi index increases with the increasing catalyst concentration and in the other fractions they do not show a clear tendency of this variation with FCC catalyst amount as well as AI, CP, O/P indexes. In the beginning of the reaction the aromatic compounds may be formed easier from the branched structure compounds and at the lower temperature the isomerization reactions are more favored than aromatization reactions. When the temperature increases, the aromatization reactions may occur easier. Besides, at higher temperature all degradation reactions may also occur via formation of free radicals. Mainly due to these reasons, the aforementioned parameters show different variations with catalyst/polymer ratio. For PP/EPDM thermolysis products of the 1st fraction AI, CP, Xa, Xi parameters change in the reverse order because the degradation products of EPDM are predominant in the 1st fraction. The values of the aforementioned parameters for this fraction are almost slightly dependent on the catalyst amount added due to the low degradation temperature of EPDM. Due to the uneven changes of reaction temperature in the reactor, the highest values of CP (in the 2nd fraction) and


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O/P (in the 2nd and 3rd fractions) are estimated for the mixtures with 10% FCC catalyst. All parameters change continually (AI, CP, Xa increase, and Xi, O/P decrease from 1st fraction to the last one) during the reaction only for the mixture of 90% PP/EPDM + 10% FCC catalyst due to steady temperature increase in the reactor. For E/P thermolysis with 25% FCC catalyst, the parameters (Xi, Xa, CP) change in the reverse order due to the low reaction temperature at the beginning of the reaction and insufficient energy amount for the aromatization reaction. For PP thermolysis in the 3rd fraction the highest value of O/P is estimated for the mixture with 10% FCC catalyst due to the thermal and catalytic processes occurring at the same time at high temperature. The estimated parameters prove that the higher amount of FCC catalyst is more favorable for the gasoline production due to the higher aromatics content. For manufacturing the fuel from plastics, the temperature control in a reactor could help optimizing the ratio of catalytic and noncatalytic degradation processes to obtain the desired composition of a fuel.

3.4 The influence of FCC catalyst on the reaction temperature and time and liquid product release temperature Generally some tendencies were determined for the processes for various plastic waste thermolysis with different catalyst/polymer ratio. The initial temperature of thermolysis reactions and the liquid product release temperature decrease with increasing FCC catalyst concentration due to the decreased activation energy. The reaction time (until the temperature reaches 773 K) prolongs while increasing FCC catalyst concentration (Fig. 6) due to the higher yields of gaseous products which impairs a thermal conductivity of the reaction mixture considerably. Fig.7 presents the reaction temperature variations with reaction times (of thermolysis of PE, PP/EPDM


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and PS). Rather similar dependences to PP/EPDM were determined for thermolysis of PP and E/P. These T vs t variations show that for all the reactions the temperature sometimes decreases mostly in the temperature range of 623-723 K due to the energy absorption of the secondary endothermic reactions (alkane cyclization and aromatization reactions). The exception is 75% PP/EPDM + 25% FCC catalyst because the degradation of this mixture begins at very low temperature (390 K) and all endothermic reactions occur gradually. The process temperatures and their change for the reaction mixtures of PE+10% FCC catalyst and PE are similar and they are in the range of 665-708 K (Fig. 7b). This proves that thermal and catalytic processes occur at the same time and the free radical reactions are the main thermolysis reactions for both processes. In Fig.7c the slight temperature drop is observed at the temperatures of ~473 K (for PS), ~461 K (for PS +10% FCC catalyst) and ~430 K (for PS +25% FCC catalyst) due to the depolymerization reactions and those temperatures are close to the liquid product release temperature (Fig.8). The dehydrogenation, hydrogen transfer and β cleavage reactions result in the temperature decrease by ~45 K for thermocatalytic PS thermolysis [20]. But for PS thermolysis , the temperature is constant and remains equal to ~623 K for 7 min which shows that the aforementioned reactions are less frequent. The liquid product release temperatures, when the first drop of a liquid product is collected in the separator, are shown in Fig.8. It is clear that the liquid product release temperatures decrease with increasing FCC catalyst concentration in the reaction mixture. 3.5 The influence of FCC catalyst to the yields of the products The yields of solid products increase with increasing FCC catalyst concentration in the mixture (Fig. 9) due to the coke formation. The exceptions are PP and PE because the solid product yields for mixtures with 10% FCC catalyst are slightly lower than those for the pure


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feedstocks because of insufficient condensation and hydrogen transfer reactions needed for coke formation. For all the types of waste the determined coke yields tend to increase with increasing FCC catalyst concentration (Table 8). The highest values of coke yields are determined for PS and PE thermolysis. The coke formation depends on polymer structure. PS thermolysis products have a lot of aromatics which are coke precursors. For PE, the coke derived from the secondary reactions, involving readily polymerizable products (dienes and olefins). For other branched or partially branched polymers coke formation occurs due to the same reason as for PE. The yields of liquid products decrease with increasing FCC catalyst concentration for PS, E/P due to overcracking and coke formation from the aromatic products. The opposite dependence is determined for PE, PP/EPDM and PP because the produced branched hydrocarbons have lower boiling points which allow them to move out of the reaction zone faster. The exceptions are determined for the PP and PP/EPDM mixtures with 25% FCC catalyst due to the overcracking. The amounts of each liquid fraction (in mass %) in relation to the total amount of liquid products fraction are presented in Table 9. The largest collected fractions usually are the 1st and the 2nd ones. The residual amount of liquid products is collected as 3rd or 4th fractions. The gas yield also depends on FCC catalyst amount in the mixture. It decreases with increasing FCC catalyst concentration for PE, PP/EPDM, PP and the opposite relationship is determined for PS and E/P (Fig.9). Process gas decreases at the expense of the condensation and coke formation reactions. The increased amount of gas shows that overcracking reactions occur during the process. The gas volume (Fig. 10) tends to increase with increasing FCC catalyst concentration for all raw materials because the lower molecular mass compounds are produced when the aromatic compounds containing short side chains are easily dealkylated in the presence


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of the acidic catalyst [21]. The gas volume change during the reaction for PP thermolysis is presented in Fig.11. The time of producing the main amount of gases is shortest for noncatalytic process, and this time increases with increasing FCC catalyst concentration. Consequently, the control of the whole process of catalytic thermolysis is more flexible compared to noncatalytic one.

3.6 The influence of FCC catalyst to the kinetics and thermodynamics The kinetic and thermodynamic parameters of thermolysis reactions were estimated for all the raw materials using the thermogravimetric data. The results are summarized in Table 10. For each material/mixture, the apparent activation energy at the beginning of the reaction is lower than that at the peak temperature. This increase in Ea is obviously indicative of a change in the rate-limiting step of the degradation kinetics from initiation to the degradation initiated by a random scission [22] or carbenium ions. Besides, this should be ascribed also to the differences in deviation from the stationary reaction state at the different heating rates. The rate of mass loss at the definite temperature is therefore related not only to the scission rate of polymers, but also to the size of volatile compounds formed [23]. The density of the samples may influence the thermal conductivity of the experimental samples. The samples with higher density have a better thermal conductivity because the density of the samples increases with increasing FCC catalyst concentration. The values of Ea are the most important parameters because all the other parameters (lnA, ∆S≠, ∆H≠, ∆G≠) are related to the activation energy directly or indirectly via the compensation effect (for lnA values) [24] and via the Eyring equation and the active complex theory (for ∆S≠, ∆H≠, ∆G≠) [25, 26].


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The activation energies for all materials decrease with increasing FCC catalyst concentration in the mixture (Table 10) because the larger is the amount of the catalyst used, the more the reaction energy barrier is reduced due to more intense formation of carbenium ions in the initial step of the reaction. The Ea values at the beginning of the reaction are lower than those at the peak temperature because the later increase in Ea is obviously indicative of a change in the rate-limiting step of the degradation kinetics [8]. The activation energies for all the plastic types thermolysis reactions are found in the literature to be 246-260 kJ/mol for EPDM [27], 230-248 kJ/mol for E/P [27], 103-116 kJ/mol for PS [28], 117-176 kJ/mol for HDPE [28] and 222.9 kJ/mol for PP [29]. In this study, the determined activation energy of plastic thermolysis differs from those presented in the literature because the exact values of the estimated Ea depends on the estimation method applied [30] and the experimental conditions as well. The Ea values at the peak temperature show a linear dependence on FCC catalyst concentration in the mixture for PE, PP/EPDM, E/P and PP (Fig.12). The similar dependency (as for Ea) is valid for the variations of values of lnA with varying FCC catalyst amount. The pre-exponential factor deals with the frequency of the collisions and the fraction that have the necessary orientation for reaction to occur. As follows, FCC catalyst helps to orient the reactive molecules and the lower amount of efficient collisions is needed for the reaction to occur. All thermodynamic parameters show similar variations with FCC catalyst concentration in the mixture because thermodynamic parameters are related to the kinetic ones (Table 10). The changes of enthalpies illustrate the energy difference between the polymer used and the activated complex formed. The values of ∆H≠ for all reactions are positive and they correlate with Ea values estimated at Tp temperature (Table 10). As follows, all thermolysis reactions are


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endothermic, and the absorbed energy from the surroundings decreases with increasing FCC catalyst concentration in the mixture. The changes of entropies of degradation reactions of plastic thermolysis have a tendency to decrease with increasing catalyst/polymer ratio because the higher amount of FCC catalyst, the more ordered structure of the system is obtained. The change of the Gibbs free energy ∆G≠ has revealed the total energy increase in the system at the approach of the reagents and the formation of the activated complex. For all materials (except for PS) the 25% of catalyst may lower the values of ∆G≠ by up to ~18 kJ/mol (as it is in the case of PP thermolysis). For PS thermolysis with 25 % FCC catalyst, the free Gibbs energy is increased by ~4 kJ/mol due to the increased Tp temperature. Tp values for PS thermolysis increase with FCC catalyst concentration due to the change in the reaction mechanism and the formation of various products from styrene. For other materials, the reaction peak temperature decreases with increased FCC catalyst concentration due to the obtained higher reaction rates at the lower temperatures. The thermodynamic parameters and lnA values of plastic waste and their mixtures with FCC catalyst cannot be compared to those published in the literature due to the lack of the data.

4. CONCLUSIONS

The comprehensive analysis of waste industrial and automotive plastics (polypropylene (PP), polyethylene (PE), polystyrene (PS), ethylene-propylene co-polymer (E/P), thermoplastic elastomer based on the ethylene–propylene–diene terpolymer and polypropylene (PP/EPDM)) thermolysis processes with 0%, 10% and 25% of equilibrium fluid catalytic cracking catalyst (FCC catalyst) was performed and the catalyst suitability for the thermolysis process was


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evaluated. The experiments were carried out in the fixed-bed reactor and with the thermogravimeter apparatus. The yields of the products depend on the catalyst/polymer ratio and the primary raw material. It is determined that the yields of gas and coke increase with increasing FCC catalyst concentration. The liquid product yield depends on the raw material and increases with increasing FCC catalyst concentration only for PE, PP/EPDM and PP. The liquid product composition depends on the catalyst/polymer ratio. The catalytic process leads to the formation of branched C7-C9 hydrocarbons (unsaturated hydrocarbons are formed more intensely than saturated ones) as the main products and also to the increased concentration of aromatic compounds. The catalyst used increases the amount of total unsaturated hydrocarbons only for polyethylene thermolysis in all fractions and this means that the acidic properties of the catalyst is excellent for this material degradation reactions and for obtaining liquid thermolysis product. Aromatization indexes, competitive parameter, the relative amounts of aromatization and isomerization reactions and the ratio of unsaturated and saturated hydrocarbons were estimated for nonaromatic raw materials in order to evaluate mechanistic pathways of the processes. It was determined that catalytic reactions occurring at the lower temperature go through carbenium ion formation and when the temperature is increased the free radical mechanism also occurs in the thermolysis of PP, PE, E/P and PP/EPDM. The kinetic and thermodynamic parameters were also estimated for all raw materials. It is determined that the activation energy decreases with increasing FCC catalyst concentration. The activation energy in the beginning of the reaction is lower than that at the peak temperature because of the change in the rate-limiting step of the degradation kinetics. Other kinetic and thermodynamic parameters (pre-exponential factor, the change of enthalpies, entropies and free Gibbs energy) also decrease with increasing FCC catalyst amount in the mixture except for the


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change of free Gibbs energy of polystyrene thermolysis. This parameter increases with increasing FCC catalyst concentration due to the change in the reaction mechanism and the formation of various products from styrene which results in the increased peak temperature. For the fuel-like production, the catalyst amount also plays an important role. For all the raw materials, the process is easier controlled and the obtained thermolysis products yield more liquids (for PP, PP/EPDM and PE) when the catalyst is added into the reaction mixture. For this reason, catalytic thermolysis of PP/EPDM, PE, PP and E/P with 25% FCC catalyst should be used for production of gasoline cut. Thermolysis of PS gives the best yields of gasoline cut when 10% FCC catalyst is used in the process. Due to the high aromatic compounds content in the thermolysis products, PS is recommended only for a gasoline cut

in order to enhance

antiknocking properties of the fuel. The thermolysis is more reasonable for the E/P, PE and PP, when the products are intended to be used for a diesel production. For the same purpose, the thermocatalytic process with 10% of FCC catalyst should be applied for PP/EPDM. For all the raw materials, the obtained thermolysis products have to be chemically stabilized before using them for the final preparation of commercial gasoline and diesel.


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Table 1. Properties of plastic waste Plastic type

Property/Element Unit C H Ash content

% % %

PP 83.92 12.48 3.60

PE 85.56 14.21 0.23

E/P 74.61 17.40 7.78

PP/EPDM 78.11 16.27 5.53

PS 91.70 7.71 0.51


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Table 2. Properties of FCC catalyst Property

Unit

Value

Activity a wt% 73.5 b Coke factor 0.79 Gas factor b 0.53 Hydrogen wt% 0.041 Total surface area m2/g 173 Ni ppm 61 V ppm 119 Na wt% 0.25 Sb ppm 1 Unit cell size Ǻ 24.24 wt% 0.20 Re2O3 Al2O3 wt% 45.9 Cu ppm 18 Fe wt% 0.42 Carbon wt% 0.11 Apparent bulk g/cm3 0.80 density Pore volume cm3/g 0.42 Average particle 83 µm size Particle density g/cm3 1.23 a Activity is “MAT-activity”. The activity is reported as the conversion to 494 K material. b

Coke factor and gas factor represent the coke- and gas-forming tendencies of the catalyst compared to a standard steam-aged catalyst sample at the same conversion.


25 Total

Branched

Linear

Cyclic

Branched

Linear

Cyclic

Aromatic

Other

Total

Branched

Linear

Cyclic 0

0.38 10.22 0.00 0.05 10.07 3.39

20.71

C16-C20

C13-C15

ACS Paragon Plus Environment

0

0

0.36 0.62 1.02

0

0

0.65 1.68

0

5.13

0

0

0

0

0 0

0

2.46 3.31

0

0

0

0.13

0

0.13

0.46 0.40 0.86

1.03 7.32 15.95

0

0

0

0

0

0

0.93

6.83 0

0

21.37 0.94

0

0

0

0

32.55

1.53

0

2.46

8.08 4.50 19.41

10.23

0.32 2.54 4.64 0.45 0.86 1.82 10.64

0

1.42 3.52 0.36 0.96 2.35

0

8.61

0

0

0 0

0.18 0

0

4.33 3.66 0

0

0 0.15 0.11 0.26

1.87 1.97 4.03

3.75 6.58 21.76 0

0

0

0

0

0

0

3.60

0

0

0

0

0

4.96

0

0

0

8.56

20.81 0.37 0.31 10.61 4.34 36.44

0.66 6.23 11.42 2.45 1.90 5.00 27.65

0

0

0 0

0 0

0

1.12 0.57 0

0

0

0

0

0 0 0 23..4 100 6

0

1.04 1.57 4.62

7.54 1.45 22.71 35.43 3.85 1.04

0

0

0.32

7.22 0.79 15.37 23.44 1.40 2.62 16.89 67.73

0

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

12.33 1.60 20.44 28.60 1.22 9.60 26.09 100 1.03 6.72 45.84 2.98 4.23 34.58 4.62 100

0

0

3.45

8.88 1.28 13.39 20.30 0.77 2.97 15.71 63.31 1.03 5.30 17.53 2.25 2.96 15.69 0.28 45.04

0

9.63 1.33 24.77 29.69 1.06 4.88 28.63 100 2.23 3.31 46.57 2.83 4.25 36.17 4.64 100

0

0

1.83

Total

C16-C20

C13-C15

C10-C12

C7-C9

C5-C6

Total

C16-C20

C13-C15

C10-C12

C7-C9

C5-C6

Total

C16-C20

C13-C15

C10-C12

C7-C9

3

1.43 4.89 34.04 100

0

0.58 3.77 4.91

0

0

2.57 14.81 37.77

0

0

0

0.98 1.19 13.89 52.33

0

0.45 0.19 0.94 3.97

0

0

0

1.99 3.83 24.52 100

0

0.45 2.35

2

0

0

0.08 0.37 0.49

0

0

1.61 2.01 14.85 67.02

0

0

0.38 0.97 3.66 18.07

0.77 5.64 14.42

0

1.93 5.90 29.81 100

0

0

0.14 0.09 0.23

0

0

0.83 1.83 3.25

0

1

0

0.29 2.57 4.41 0.26 0.60 2.00 10.13

7.80 1.04 19.74 21.97 0.80 2.66 18.91 72.93 2.23 2.86 15.08 1.89 3.60 14.64 0.14 40.44

0

0

0

0

0.21 2.22 9.64 24.07

0.13 0.02 0.41 0.00 0.00 1.14 0.00 0.00 2.26

0.04 1.78 2.07

C5-C6

0

0

0

0

0

0

0

0.25

0.56 2.29 16.33 63.78

0

0

1.16 0.42 1.92 8.67

0

0

0.00 22.37 0.62 0.22 14.88 0.21 38.30

Total

0

0

0

2.14 5.62 30.64 100 0.03 16.27 1.73 19.82 22.91 2.36 3.96 32.66 100 3.09 6.07 45.53 3.03 1.82 39.74 0.72 100

0.06

0.06

0

0

0.37 0.94 1.83

3.50 0.75 4.79 5.26 0.24 0.86 12.55 27.95

Fraction number Carbon

0

0

C10-C12

Aromatic

0.47 1.75 8.22 21.01

Cyclic C7-C9

Linear

1.20 2.48 17.59 60.84 0.03 12.25 0.75 12.49 14.20 1.63 2.35 16.35 60.06 3.09 5.48 10.59 2.41 1.20 11.55 0.51 34.84

0 C5-C6

Branched 0

Structure

2.75

Cyclic 0.34 0.98

Linear

0

Branched

0.51 0.23 2.29 3.45 0.49 0.58 1.95 9.51 0.00 0.21 1.21

Saturated HC Total

0

Unsaturated HC content

0.46 0.96 3.89 16.27

Unsaturated HC

10

Saturated HC

Saturated HC

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Catalyst concentration, %

Page 35 of 59 Energy & Fuels

Table 3. The liquid products distribution (mass %) of PE thermolysis

4

35

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 0

0

0


0

0.04

0

0

0

0.11 1.05 1.23

0

0

0

0

0 0

0.56 0.27

0.31 30.30 1.33 13.73 14.20

0

11.87 0.20 3.44 4.87 0

0

0.31 18.42 1.02 8.41 8.10

0

0

0

10.74 2.17 21.81 34.94

0

0 0

0

0

8.65 1.51 14.47 23.94 2.10 0.18 2.94 2.79

0.47 4.36 8.22 0

0 0

0

0

0.59

14.02 4.02 23.53 20.78

0

0 0 0

0

0 0

3.10 0.51 5.11 3.27 0

0.25 2.38 2.53 10.92 3.26 15.44 14.98

0

13.82 3.17 20.36 24.25

0

0

0

0

0

0

0 0

0.51

2.51 0.08 4.19 3.79 0

Cyclic 0

10.72 2.61 11.93 14.31

Other 0

Linear

0

0.59 0.48 3.72 6.15

Branched

0

Aromatic

0

Unsaturated HC

Energy & Fuels Page 36 of 59

36

25 Aromatic

Other

Total

Branched

Linear

Cyclic 0

0

0

0

0

0.33 0.09 0.09

0 0

0.34 0

0 0

0.19 0

0 0

0

0.09

0.95

C16-C20

C13-C15


0

0

0

0

0

0

-

-

-

-

-

-

-

-

-

-

-

-

-

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.29

0

0 0

0

0

0.08 0.07 0.21

1.07 9.75

0

0

0.65

1.09 1.48 13.40

0.52 5.44 16.60 1.35 1.17 1.45 26.53

0

0

0

0

0 0

0

2.58 3.04

0

0

0

0

0 0

0 0

0

1.41

0

0.11 0.66 6.61 0.22

0

0

0

0

1.93

0

0.44 0.30 2.67

0

0.06

0

0

0

0

0.40

0.24

0

0

0.18

0

0.48 0.52 0.21 0.12 2.66

0

5.26 30.02 4.21 1.13 4.42 45.25

2.64 2.15 1.76 33.38 1.58 1.01 6.43 48.94

0

0

2.29 0.29 7.20 6.24

0.25 2.75 19.02

0.74 8.75 67.03

15.90 2.00 22.10 44.63 0.82 1.13 13.43 100

0

0.29 3.11 7.67 0.82 0.14 1.93 13.96

13.61 1.42 11.79 30.72

0

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

4.96 1.03 19.64 60.47 2.22 2.15 9.53 100 1.63 2.70 2.15 7.66 65.33 6.31 2.97 11.26 100

0

0

0.22

4.74 0.51 11.62 40.82 0.87 0.87 7.42 66.86

0

Total

C10-C12

C7-C9

C5-C6

Total

C16-C20

C13-C15

C10-C12

C7-C9

C5-C6

Total

C13-C15

C10-C12

C7-C9

3

-

-

-

0.91 2.35 28.34 100

0

0.90 7.79 14.94

0

0

1.58 0.86 2.22 54.21 3.75 1.33 7.70 71.66

0.14 0.48 8.61 0.40 3.05 1.61 14.30

8.35 0.47 20.43 55.80 1.15 2.56 11.24 100 0.29 1.58 1.00 3.85 72.65 4.36 5.47 10.79 100

0

1.73 0.10 9.54 14.99 0.81 1.11 5.08 33.35

0

0

2

0

0

0

0.41 0.75 17.61 69.82

0

0

0

0.50 0.70 2.94 15.24

0

0

0

0

1.96 2.92 27.76 100

0

0.96 7.27 15.37

1.14 5.79 62.16

0

1

0

0

0.08 0.77 2.62 0.34 0.31 0.37 4.49

6.62 0.29 10.13 38.19

0

0

0

0

0.61 0.81 16.50 64.20

0

0

C10-C12

C5-C6

0

0

1.77 18.93 1.18 0.16 2.24 24.28

0

0

0

0

1.35 1.15 3.99 20.43

0

0

0

C7-C9

C5-C6

Total

0

0

2.16 5.06 0.26 0.32 2.82 11.04

0.63 0.32 4.27

Structure

4.04 2.25 22.08 100 0.08 10.92 0.62 12.73 56.25 1.57 2.41 15.42 100 0.33 17.35 0.81 3.30 67.09 4.40 1.73 4.99 100

0

0

0

0

16.39 0.72 1.19 45.72 3.03 0.94 2.43 70.41

2.45

Fraction number

0

0.42

0

Cyclic

0

Linear

0

Branched

0

Cyclic

0.05 0.07 0.17 0.32

Linear 0

Branched

0

Total

1.14 0.36 6.01 18.70

Other 0

Aromatic

1.97 0.78 12.99 63.75 0.08 10.50 0.42 8.70 43.82 0.58 1.04 10.99 76.12

Cyclic 0

Linear

0

Branched

0.87

Cyclic

0

Linear

0.20 1.88 7.37 0.73 1.05 1.62 12.84

Branched

0

Saturated HC Total

0

Unsaturated HC

%

Carbon content

0.87 1.03 2.91 17.22

10 Unsaturated HC

0

Saturated HC

Saturated HC

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Catalyst concentration,


Table 4. The liquid products distribution (mass %) of PP/EPDM thermolysis 4

37

0

Linear

Cyclic

0.27 3.14 9.00

Branched

Other 0 0

0.03 0

0 0

0

0

0

1.90 7.85 0

0

0


0 0

0 0

-

-

-

-

-

0

0

0

0

0

0

-

-

-

-

-

-

-

-

-

-

-

-

21.84 0.61 13.72 32.23 -

0

3.05 0

1.08 2.12

17.76 0.35 10.09 22.85

0

0

1.03 0.26 2.55 7.26

0

0 14.44 0.51 15.28 37.13

0 0

0

2.08 2.88 0

0

2.17

0

0.27 4.04 9.63 12.27 0.24 9.16 24.61

0 0

0

0.03 9.65 1.52 11.28 48.83

1.43

0

0.32 8..22 1.25 6.23 31.98

Aromatic

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Unsaturated HC


38

25 0.29 3.30 13.11 1.12 0.44 2.49 20.76


0

1.03

0

0

0 0

26.46 1.52 2.24 28.48 100

0

0.09 0.09

0

0

0 0

0 0.23

0.48

0

0

0

0

0

0.23

0.94 1.42

5.54 3.37 15.73 46.53 8.80 1.08 18.95 100

0

0

-

-

-

-

0

0

0

0

0

0.14 4.21

0

0.94 0.50 5.79

0

0

0

0

0

0

2.52 13.36 1.83 0.99 3.12 21.83

0.13

0

0

0

0

0.13

2.38 4.81 0.54 0.83 1.96 10.52

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

3.51 10.68 62.26 5.87 8.88 5.80 100

0

0

3.01 7.06 45.01 4.62 4.31 5.46 69.48

0.50 1.11 12.43 0.71 3.74 1.38 19.87

1.33 5.52 70.10 8.71 4.46 9.89 100

0

0

1.33 2.86 52.52 6.87 2.52 6.27 72.38

0

Total

C13-C15

C10-C12

C7-C9

C5-C6

Total

C13-C15

C10-C12

C7-C9

C5-C6

Total

C13-C15

C10-C12

C7-C9

C5-C6

Total

C13-C15

C10-C12

3

0

0.59 7.21 13.48 8.52 0.93 4.91 35.64

5.54 2.78 8.53 32.34 0.28 0.15 13.10 62.71

0

0

0

4.32 0.05 1.25 10.41 26.97

0

0

0

19.14 0.58 0.68 15.92 64.32

0

-

0

0

0

3.00 0.89 0.31 2.06 8.62

0

0

0.87 2.34

43.25 2.72 1.31 20.91 100 0.31 3.39 2.21 14.99 60.53 2.61 1.53 14.42 100

0

0

0

0.35 7.08 18.34 0.28 0.26

2.72 5.84 0.25 0.09 3.04 12.48

0

4.76

0

0.34 2.07 79.50 6.93 2.46 8.69 100

0

0.80 17.65 0.25 0.45 3.17 22.32

C7-C9

C5-C6

2

0

0

0

34.66 2.03 0.96 12.09 74.09 0.03 3.13 1.85 8.04 42.61 0.55 0.71 9.08 66.10

0 0

0.87 5.22

0

0.36 4.23 12.08 1.81 0.63 2.30 21.41

0

0.65

2.80 0.69

0

0

0

0

0

0.08 0.39 0.16

1.20 0.19 3.76 8.96 0.53 0.72 5.00 20.36

4.06 1.62 5.03 35.83 1.56 0.45 8.76 57.32

0

0

0

47.87 2.94 1.51 26.19 100 0.08 5.65 2.26 12.09 58.56 3.21 1.76 16.38 100

0

0

0

0

0

0.15 0.13 1.56

0

0

0

0

0

0

0

2.86 5.04

0

0

0.34 1.27 58.88 6.68 1.31 5.24 73.73

0.70 0.29 3.96

1

0

0

3.97 1.94 13.49 53.75 4.06 2.04 20.75 100

0

0

0

0

Fraction number

0

0

Branched

1.80

Cyclic 0

Linear

33.28 0.30 0.66 17.32 67.81

Branched 0

Total

12.79 2.64 0.85 6.02 27.16

Other 0

Aromatic

39.45 1.18 2.73 27.79 100

Cyclic

0

Linear

0.20 0.06 0.50

Branched

0.24

Cyclic

0.12 0.09 0.93 2.96 0.55 0.10 3.38 8.12

Linear

0

Branched

6.34 0.26 1.48 10.59 23.88

Total

3.85 1.49 7.79 37.89 1.23 0.89 13.08 66.23

Aromatic

0

Cyclic

29.73 0.22 0.77 15.67 68.76

Linear 2.96

Branched

0

Cyclic

0

0

0

Linear

0.36 4.77 12.90 2.27 1.05 4.29 25.64

Branched

0

Saturated HC Total

3.14 0.70 0.28 1.47 6.86

Unsaturated HC

Structure

0

Unsaturated HC

10

Saturated HC

Saturated HC



Table 5. The liquid products distribution (mass %) of PP thermolysis

Carbon content

4

39

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 0.10 1.17

Linear

Aromatic

0

0

0.36 4.51

0

0

0

0

0.86


0

0.44

0.15 2.21

0

0 25.75 2.84 12.71

0

6.93 1.23 2.78

18.82 1.46 7.72

0

12.51 3.43 15.86

0

2.40 0.69 3.06

10.11 2.74 11.50

0

8.58 2.77 10.14

0

0.15 0.23

8.43 2.18 5.64

0

12.82 4.18 11.84

0

2.55 0.75 1.91

10.27 3.33 8.76

Cyclic 0

Unsaturated HC


40

25 Other

Total

Branched

Linear

Cyclic

ACS Paragon Plus Environment 0 0

1.33

0.03

0.57 0.51 15.46 57.19 0 0 0 0 0 0 0 0

1.36 16.54 40.85

0.63

100

0.82 8.66 15.26

100

0.60 2.00 32.76

18.87 69.05

0.07

0

0.55 0.60 3.16 15.61

0.07

0.13 0.50

0

0

0

1.32 1.42 30.77

0

0.23 1.15 13.41 63.30

0.23 1.30 25.12

0

100

0 0

0

0

0

0.07 0.02 10.55

0

0

2.58 4.06

0

0.25 3.40 10.77

0.29 6.72 10.73 1.08 0.62 3.26 22.70

0

0 0

0

2.30 4.50 0

0 0

0

0

0.57 2.61 10.61

0.27 3.93 12.70 1.24 0.45 1.89 20.48

0

0 0

0

4.31 6.38 0

0 0

0.03 0.03 0.63

0.15 2.27 13.64 0.65

0

0

0

0

0

0

0

0

0 0

0.14

8.45 9.83 0

0

1.24 7.74

0

0.18 0.32

0.25 5.53 26.25

0.40 9.61 65.69

0

10.14 0.57 22.13 49.63 0.31 0.65 16.56 100

0

2.18

0

0.14 1.50 4.55 0.31

7.95 0.43 12.18 35.11

0

0

0

0

0

0

3.47 0.68 18.68 57.58 2.16 0.93 16.50 100 1.28

0

0.53

2.94 0.41 10.43 38.50 0.91 0.33 12.32 65.84

0

4.53 0.50 16.47 57.91 1.80 1.72 17.07 100

0

0.62

3.91 0.21 7.45 42.67 0.72 0.52 11.20 66.69

0

0

0

0.16 0.40 8.77 0.55

0

1.43 11.31

0.30 8.51 0.09 3.60 1.03 13.53

0

0

0

0.33 13.70 1.20

0

0

0

0

1.69 16.92

0

2.12

0

0.21 0.22 2.55

0.52

0

0

1.99 23.16 4.07

0

0

0

1.15

2.60 32.47

0

0.98 0.37 0.39 3.14 0.02 20.33

2.03 3.00 79.17 8.63 0.56 5.33 100

0

0

2.03 0.49 53.89 4.55 0.35 2.51 63.82

0

3.43 1.07 81.33 3.39 4.11 6.18 100

0

0

3.43 0.44 59.62 2.09 0.51 3.46 69.55

0

0

0

0

0

0.27 1.07 8.90 0.97

0

0

0

0

1.28 12.49

0.31 2.67 3.49 64.64 5.27 3.31 4.88 100

0

0

0.31 2.40 1.44 55.38 3.91 0.17 3.58 67.19

0

0

0

0

0

0

0

0

0

0

0

0.26 1.34 2.02 81.78 3.92 3.98 6.69 100

0

0.26 1.13 1.11 64.63 3.20 0.45 4.15 74.93

Total

C13-C15

C10-C12

C7-C9

C5-C6

Total

C13-C15

C10-C12

C7-C9

C5-C6

Total

C13-C15

C10-C12

C7-C9

C5-C6

Total

C10-C12

C7-C9

3

0

0.48

0.07 4.84 0.76 13.25 61.27 0.60 2.18 17.03 100

100

1.24 1.07 24.55

0

2.41

0.08 11.69 26.15

Aromatic

0

Cyclic

0

Linear

2

0

Branched

0

Cyclic

1

0.77

Linear

0.26

Branched

0

Total 0

C5-C6

Fraction number Carbon content

0.06 0.12 1.52

Other

0.07 4.36 0.56 8.49 47.70 0.06 1.05 11.48 73.77

Aromatic

0.75 0.40 16.38 66.50

Cyclic 0.05 0.51 8.39 0.17 3.53 1.11 13.76

Linear

0

Branched

0

Cyclic

0.20 2.17 9.51 0.54 0.88 2.15 15.46

Linear

0

Saturated HC Branched

0

Unsaturated HC Total

0.43 0.55 6.65 31.09

10 Unsaturated HC

0

Saturated HC

Saturated HC



Table 6 . The liquid products distribution (mass %) of E/P thermolysis 4

Structure

41

Cyclic

4.30 1.06 11.77 56.00

0 0 0

9.03 0 24.99 0

0 0 0 0

0 12.31 27.33

0

6.14 7.77

5.96 18.73

0.21 0.83


0

0

0

0

0

0

0.83 1.87

0.01

0

0.42 0.87

0

0

0

0

0

0

2.17 2.76

0.18 31.55 0.13 7.65 24.68

9.44

0

0.18 22.09 0.13 5.06 21.05

0

0.03 18.91 0.41 12.96 34.18

3.07

0

0.03 15.83 0.18 8.81 24.56

0.23 3.31 7.75

0

15.96

0

0

0

0

0.08 0.49 0

0

0.14

Other 0

0.38 5.75 17.32

Linear

4.16 0.68 5.93 38.19

0

Branched

0

Aromatic

0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Unsaturated HC


42

Page 43 of 59

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Table 7. The average yields of gasoline and diesel fractions FCC catalyst concentration, % 0 10 25

Yields of gasoline cut, mass %

Yields of diesel cut, mass %

PP/EPDM

PE

PP

E/P

PS

PP/EPDM

45.34 51.87 69.38

11.26 46.73 59.01

29.69 60.41 62.48

41.95 58.59 71.77

65.41 66.74 63.42

37.42 38.14 22.45

PE

PP

E/P

PS

49.88 28.71 28.71

44.46 32.07 31.34

39.22 35.15 25.16

28.80 23.63 22.53

Table 8. The average yields of coke (mass %) FCC catalyst concentration, % 0 10 25

Plastic type PP PP/EPDM 4.61 13.26 17.42 14.68 31.56 29.88

E/P 5.64 9.80 26.85

PS 28.35 31.37 81.81

PE 21.05 53.11 99.35


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Page 44 of 59

Table 9. The amounts of each liquid fraction (in mass %) in relation to the total amount of liquid products fraction FCC catalyst concentration, % 0 PE 10 25 0 PP 10 25 0 E/P 10 25 0 PP/EPDM 10 25 0 PS 10 25 Plastic type

% of the whole liquid products for each fraction 1 2 3 4 43.19 39.21 17.61 0.00 31.57 36.69 28.49 3.25 33.03 31.37 30.11 5.49 43.14 27.78 29.08 0.00 27.38 27.85 28.81 15.96 29.27 31.29 30.86 8.57 28.26 23.59 29.71 18.44 24.48 28.46 26.75 20.31 27.30 27.42 26.66 18.61 47.92 36.96 15.12 0.00 30.62 35.14 29.36 4.88 33.21 34.25 32.53 0.00 30.44 31.27 30.77 7.52 34.74 36.20 29.06 0.00 33.58 33.89 30.88 1.65


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Table 10. Kinetic and thermodynamic parameters of thermolysis reactions for all raw

E/P

PP/ EPDM

PE

PS

PP

T p, K

kJ/mol

∆G≠,

kJ/mol

∆H≠,

J/(mol K)

∆S≠,

[A/min-1]

lnA,

kJ/mol

Flynn-Wall method

Ea,

[A/min-1]

lnA,

kJ/mol

ASTM E1641 method

Ea,

Catalyst concentration, %

materials

Feedstock

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

0

187.03

31.14

187.91

30.39

-7.60

182.14

187.42

694.7

10

164.10

26.07

167.52

27.41

-32.14

161.87

183.72

679.9

25

102.37

15.33

106.02

17.20

-116.68

100.66

175.93

645.2

0

161.65

24.94

200.95

31.30

-0.40

194.94

195.23

722.5

10

114.03

16.69

166.57

26.48

-40.11

160.77

188.72

696.8

25

95.62

12.48

102.82

15.75

-129.04

97.24

183.85

671.2

0

192.70

29.36

204.74

31.91

4.73

198.73

195.31

723.2

10

177.60

28.03

190.51

30.14

-9.85

184.61

191.59

709.2

25

168.69

27.43

170.43

27.75

-29.41

164.74

184.86

684.2

0

184.13

30.52

248.91

43.09

98.29

243.36

177.78

667.3

10

156.44

24.97

214.38

36.17

40.66

208.76

181.26

676.3

25

126.89

19.83

213.71

35.99

39.20

208.08

181.53

677.2

0

125.37

18.40

251.01

40.62

77.23

245.11

190.26

710.2

10

91.33

13.52

173.59

29.10

-17.98

168.03

180.04

668.2

25

72.44

10.13

136.60

23.36

-65.39

131.27

173.14

640.3


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Figure 1.

Page 46 of 59

Schematic diagram of thermolysis unit: 1, reactor; 2, heating furnace; 3,

thermocouple; 4, pressure transducer; 5, valve; 6, air condenser; 7, safety valve; 8, separator; 9, liquid product tank; 10, water reflux condenser; 11, gas meter; 12, torch.

Figure 2. Composition of PS thermolysis products 46 ACS Paragon Plus Environment

Page 47 of 59

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a.

b.


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Page 48 of 59

c.

d.

Figure 3. The average composition of the liquid thermolysis products of all fractions for PP (a), PE (b), PP/EPDM (c), E/P (d)


Page 49 of 59

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

a.

b.


Energy & Fuels

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Page 50 of 59

c.

d.

Figure 4. The values of AI, CP, Xa, Xi parameters for PE (a), PP/EPDM (b), PP (c), E/P (d)


Page 51 of 59

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure 5. The values of O/P parameter


Energy & Fuels

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Page 52 of 59

Figure 6. The variations of reaction time with FCC catalyst concentration


Page 53 of 59

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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a.

b.


Energy & Fuels

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Page 54 of 59

c.

Figure 7. The variations of reaction temperature with time for PP/EPDM (a), PE (b) and PS (c)

Figure 8. The variations of liquid product release temperature with FCC catalyst concentration


Page 55 of 59

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure 9. The yields of thermolysis products

Figure 10. The variations of gas volume produced with FCC catalyst amount


Energy & Fuels

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Page 56 of 59

Figure 11. Gas volume variation with time for PP thermolysis

Figure 12. Linear dependence of activation energy estimated by Flynn-Wall method and FCC catalyst concentration


Page 57 of 59

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Energy & Fuels

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The influence of equilibrium FCC catalyst amount on the thermolysis

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