Pyrolysis for PET Bottle Chemical Recycling

Abstract This paper focuses on the green recycling technology of Polyethylene Terephthalate (PET), which, as most widely consumed textile fiber globally, has become a key area in waste research. While traditional acid‐catalyzed methods have demonstrated value PET depolymerization, harsh acidic reaction conditions pose significant technical challenges, including catalyst deactivation and severe equipment corrosion. Based principles chemistry engineering, this study innovatively develops temperature‐sensitive heteropolyacid catalyst, (HOCH 2 CH N(CH 3 ) x H 3‐ PW 12 O 40 (Ch , = 1, 2, 3), synthesized by ion exchange between choline chloride phosphotungstic acid. Under optimized (200 °C, 7 h, solid–liquid ratio 1:10, 0.2 g catalyst), achieves 99% conversion rate 96% recovery terephthalic acid (rTPA), with product purity reaching 99.7%. Kinetic studies based first‐order mechanisms reveal an apparent activation energy E 86.72 kJ/mol for hydrolysis reaction. Notably, through temperature regulation crystallization techniques, used Ch 3‐x can be easily recovered from product, ma... Read More

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Due to their various chemical structures, long chain polymeric compositions, and thermal/decomposition behavior of plastic waste (PW), it is challenging recycle into hydrocarbon fuels. Thus, necessary carry out proximate ultimate because this will enable proper design a feasible pilot plant for management (PW). In study LDPE (low-density polyethylene), HDPE (high-density polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC) were the evaluated PW samples. accordance with ASTM standards E790, E897, E830, respectively, analyses PW's moisture content, volatiles, ash content carried out. A Vario Micro Element Analyzer was used determine analysis. To how composition (PW) changed temperature time, mass loss measured using thermogravimetric analyzer (SII 6300 EXSTAR, Seiko Instruments Inc., Tokyo, Japan. bomb calorimeter (ASTM D 5865-85), which measures heat produced at constant 298 K from burning dry sample, experimentally calculate heating value (HV). The results obtained revealed that all samples had percentage volatile matter ranging 88.66 99.57... Read More

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Developing highly efficient and selective catalysts for chemical recycling upcycling of plastic waste is essential establishing a sustainable plastics economy reducing environmental impact. Here, we report novel tetranuclear titanium catalyst that enables transesterification reaction esters polyesters. Detailed experimental computational studies have revealed bi‐titanium framework facilitates dual activation mechanism, activating both alcohol ester simultaneously, thereby significantly enhancing the process. This demonstrated exceptionally high activity in methanolysis poly (ethylene terephthalate) (PET) with an up to 1.9 ×107 gPET molTi−1 h−1 at 0.005 mol % loading, producing polymerizable dimethyl glycol monomers. Additionally, it effectively catalyzed re‐polymerization recovered monomers, yielding original polyester molecular weight achieving ideal circular commodity Furthermore, this can also be utilized upgrading PET via 1,4‐butanediol, polybutylene adipate, poly(tetramethyene ether glycol), engineering plastic, biodegradable polyester, thermoplastic elastomer, respec... Read More

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Chemical depolymerization and recycling of poly(ethylene terephthalate) (PET) constitute a sustainable, resource-efficient, environmentally beneficial approach, which requires the development efficient heterogeneous catalysts. Herein, polyoxometalate(POM)-based zinc-organic networks were synthesized as dual-site acid catalysts for alcoholysis PET into value-added terephthalic (TPA) product, with formulas [Zn2(μ2-Cl)(H2O)2(DTAB)3][PW12O40]·4H2O (1), [Zn2(DTAB)4][SiW12O40]·4H2O (2), [Zn2(H2O)4(DTAB)2.5][HBW12O40]·8H2O (3) (DTAB = 1,4-di(4H-1,2,4-triazol-4-yl)benzene). Structural analysis showed that compounds 1 2 composed 2D Zn-ligand embedded POM clusters in an "egg-in-a-box" manner compound 3 consisted 3D POM-based host-guest framework constructed by {Zn2(H2O)4(N-N)3} units [HBW12O40]4- clusters. Three incorporate Zn2+ Lewis centers heteropolytungstate clusters, having strength order > 2. When employed catalysts, three exhibited catalytic performance TPA >92% conversion rate >94% selectivity along excellent recyclability structural stability. This work offers novel perspective up... Read More

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Raw material supply system and method for pyrolyzing waste plastic containing PVC and PET while treating the chlorine and acid contaminants. The system involves feeding slaked lime to the plastic at a ratio of 1-4 moles lime to total PVC and PET moles. This mixture is heated to dechlorinate the PVC and hydrolyze the PET. The lime-melted plastic is then supplied to the pyrolysis furnace. This pre-treatment removes chlorine from PVC and breaks down PET acidic components to prevent fouling and corrosion in the pyrolysis furnace.

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Continuous, efficient conversion of waste plastics into hydrocarbon products like oil, gas, and char using a rotatable kiln reactor, condensers, and separators. The kiln has features like sweeping and lifter walls that aid mixing and material flow. The condensers cool and separate the products. The separators further separate the oil from solid char. This allows continuous, high-yield conversion of plastics with efficient heat transfer and fouling mitigation compared to batch processes.

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A fluidized bed reactor with a rotating shaft and blades inside the reactor chamber to create a mechanically agitated, adjustable density fluidized bed without vibration or gas injection. This enables processing organic materials with lower retention times due to the high-fluidized bed density. The rotating blades also provide mechanical separation of dust particles from the gas stream. The reactor is flexible for multiple processes like pyrolysis, gasification, combustion, catalysis, and heat exchange. The rotating shaft drive is controlled based on reactor and separator chamber sensor feedback.

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A method and apparatus for converting plastics into hydrocarbon products using pyrolysis in a dual fluidized bed reactor. The method involves preheating and shearing the plastic feed in an extruder to reduce viscosity for atomization and dispersion in the reactor. The plastic feed is then injected into the reactor where it pyrolyzes into hydrocarbons. The reactor has a cyclonic separator to remove the hydrocarbon vapors from the char and heat carrier. The char is combusted in a separate bed to regenerate the heat carrier. This prevents hydrocarbon loss and allows higher throughput. The cyclone, stripper, and regenerator are all designed to handle corrosive plastic contaminants.

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Continuous pyrolysis system for recycling waste plastics that avoids issues like sticking, coking, and low yields. The system uses a stirring assembly inside the pyrolysis reactor with a rotating shaft and stirring rods to prevent plastic from accumulating. The stirring breaks up and removes molten plastic before it adheres to the reactor walls. The system also has multiple connected pyrolysis units that allow continuous operation without stopping for material changes. The final unit has a separation unit to separate the pyrolysis products into oil, gas, and solid fractions.

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Thermochemical conversion of waste plastics into useful products like petrochemicals, fuels, and asphalt. The process involves melting the waste plastic in a tank and then pyrolyzing it in a reactor. The melting step removes water and oxygen to prevent coking. The pyrolysis is done at lower temperatures to produce pitch instead of tar. This allows higher oil yield. The pyrolysis oil is separated into gases, light oil, medium oil, and heavy oil fractions. The system uses controlled heating and stirring to optimize conversion and prevent coking.

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Chemical recycling of waste plastics with lower carbon footprint by using waste heat integration. The process involves liquefying the waste plastics, pyrolyzing them, separating the pyrolysis products, and then feeding some of the separated pyrolysis oil back into the pyrolysis zone. This closes the loop and reduces the need for external fuel to heat the plastics. The pyrolysis effluent is also used to indirectly heat the pyrolysis oil, further reducing external fuel. The process can be operated at high pressures (>200 psig) to enable efficient heat transfer.

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Chemical recycling of waste plastics with lower carbon footprint by integrating heat recovery from the pyrolysis flue gas to liquefy and further heat the waste plastics. The process involves pyrolyzing liquefied waste plastics, recovering heat from the pyrolysis flue gas to liquefy the waste plastics, and further heating the liquefied plastics using flue gas heat. This reduces the need for fossil fuel combustion to provide heating.

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A chemical recycling process with lower carbon footprint by integrating heat recovery and utilization across the recycling steps. The process involves liquefying waste plastic, pyrolyzing it, cracking the pyrolysis oil, and generating steam. Heat from pyrolysis flue gas, cracker flue gas, quench fluid, residual steam, and combustion flue gas is used to preheat the initial feed streams like the waste plastic, combustion fuel, and combustion air. This reduces the need for external fossil fuel combustion for heating, thereby lowering CO2 emissions.

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Two-step plastic recycling process to convert waste plastics into monomers like ethylene and propylene. The process involves pyrolyzing the plastics at 300-600°C in a first stage to produce low-temperature pyrolysis products. Then, a portion of those products is heated to 600-1100°C in a second stage to further pyrolyze into monomers. This two-step process allows converting plastics into monomers with higher yields compared to single-stage high-temperature pyrolysis.

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A process for converting plastic waste into liquid hydrocarbons with improved yield and efficiency compared to existing methods. The process involves two steps: 1) thermocatalytic degradation of the plastic in a reactor at high temperatures to produce a mixture of gases and liquids, and 2) condensation of the gases to separate and collect the liquid hydrocarbons. A key feature is recycling a portion of the liquid slurry from the reactor back into it, rather than discharging the entire slurry. This improves hydrocarbon yield and reduces the amount of solid charcoal that forms. The process can be scaled up to commercial levels for converting large amounts of plastic waste into valuable liquid hydrocarbons.

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Waste plastic pyrolysis apparatus that improves efficiency and productivity of low-boiling pyrolysis oil production. The apparatus has a melting section, thermal decomposition section, and reactive distillation column. Waste plastic is melted, rapidly pyrolyzed, and decomposed using recycled high-temperature gases. Uncondensed gases separate and recirculate to maximize thermal contact, increase reaction rates, and further decompose unreacted materials. This avoids carbonization and reduces energy consumption compared to separate units.

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A containerized plastic waste pyrolysis plant that can efficiently convert plastic waste into hydrocarbon fuels like diesel. The plant is designed to be modular, portable, and scalable for deploying in various locations. It uses containerized units with pyrolysis reactors, flash distillation, fractionation, and scrubbing steps to convert plastic waste into hydrocarbon fuels. The plant can handle smaller feed sizes than fixed plants, making it suitable for mobile deployment. The containerized design allows easy shipping and assembly, while the modular units can be combined in series or parallel to scale output. The plant can also generate electricity from the pyrolysis gas byproducts.

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Process for making recycled content hydrocarbon products from waste plastic pyrolysis vapor. The process involves co-locating waste plastic pyrolysis and cracking facilities. The pyrolysis vapor is withdrawn from the pyrolysis facility at a certain temperature, then introduced into the cross-over pipe between the cracker furnace sections. This prevents condensation since the vapor temperature is higher than the cracker furnace sections. By combining and cracking the vapor with the cracker feed, it enhances energy efficiency and reduces waste heat losses compared to separate facilities. The vapor introduction rate is adjusted as cracker feed rate changes to maintain furnace heat balance.

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Simultaneous pyrolysis of mixed plastics containing PET (polyethylene terephthalate) and polyolefin plastics like PP and PE to efficiently recycle complex plastic waste streams. The method involves pyrolyzing the mixed plastic feed at high temperatures in the presence of steam and nitrogen. The pyrolysis converts the mixed plastics into terephthalic acid (TPA) and olefin monomers like ethylene and propylene. The high H/C ratio of PET and the acid catalytic effect of TPA in the mixed plastic feed synergistically enhance the pyrolysis yield of TPA and olefins compared to pyrolyzing the plastics separately.

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Process for recycling waste plastic into hydrocarbons and a plant for implementing it. The process involves depolymerizing waste plastic in a heated reactor filled with molten salt to break down the polymer chains into gaseous hydrocarbons. The plant has features like scraper blades to prevent floating of plastic, mixing to dissolve, and jacket heating with salt circulation. The hydrocarbons are fractionated into fuels and gases. The plant also has steps to prepare the plastic feed, remove contaminants, and reduce size. This allows recycling of difficult-to-recycle waste plastics into valuable products.

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