Latest Advances in Waste Plastic Pyrolytic Catalysis

With the increase in demand for plastic use, waste plastic (WP) management remains a challenge in the contemporary world due to the lack of sustainable efforts to tackle it. The increment in WPs is proportional to man’s demand and use of plastics, and these come along with environmental challenges. This increase in WPs, and the resulting environmental consequences are mainly due to the characteristic biodegradation properties of plastics. Landfilling, pollution, groundwater contamination, incineration, and blockage of drainages are common environmental challenges associated with WPs. The bulk of these WPs constitutes polyethene (PE), polyethene terephthalate (PET) and polystyrene (PS). Pyrolysis is an eco-friendly thermo-chemical waste plastic treatment solution for valuable product recovery, preferred over landfilling and incineration solutions. In this extensive review, a critical investigation on waste plastic catalytic pyrolysis (WPCP) is performed, including catalyst and non-catalyst applications to sustainably tackle WP management. Current catalysis techniques are revealed, and some comparisons are made where necessary. Common pyrolytic products and common shortcomings and errors related to WP catalysis were also identified. The benefits of catalysts and their applications to augment and optimise thermal pyrolysis are emphasised. With all these findings, and more, this paper provides reassurance on the significance of catalysis to industrial-scale applications and products and supports related WPCP research work concerning the environment and other beneficiaries

Characterization and Distillation of Pyrolysis Liquids Coming from Polyolefins Segregated of MSW for Their Use as Automotive Diesel Fuel

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Energy & Fuels, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.energyfuels.0c00403.[EN] The liquids resulting from pyrolysis of industrial plastic waste (IPW) and postconsumer colored and white plastic film waste (PCPW and PWPW, respectively) at the pilot scale (80 kg/h) were widely characterized by different techniques to assess their potential as both petrochemical raw material and automotive diesel fuel. It was found that pyrolysis liquids mainly consisted of hydrocarbons in the diesel boiling point range (180-380 degrees C), amounting to approximately 50-55 vol %. Therefore, the results were further contrasted with limits established by the EN 590:2014 + A1:2017 standard for automotive diesel fuel. Although pyrolysis liquids showed good properties, they do not conform to some key fuel parameters for diesel engines, such as density, distillation curve, kinematic viscosity, flash point, and cold filter plugging point. To improve these properties, PWPW pyrolysis liquids were distilled in the diesel range and the liquid fractions were characterized according to automotive diesel standards. It was found that the diesel fraction met all specifications with the exception of the cold filter plugging point (-10 to 4 degrees C vs -10 degrees C winter/0 degrees C summer) and density (800-807 vs 820 kg/m(3)). To accomplish these standards, a blend of diesel obtained from PWPW pyrolysis liquids and commercial diesel (50/50 wt %) was also prepared and analyzed. Results revealed that the blend met the requirements of the 21 parameters demanded by the standard for a product to be marketed and used as automotive fuel in diesel engine vehicles.The authors acknowledge the financial support of the Centre for the Development of Industrial Technology (grant number IDI-20150730) and the Ministerio de Ciencia, Innovacion y Universidades (Spain) (grant number DI-16-08700).Gala, A.; Guerrero, M.; Guirao, B.; Domine, ME.; Serra Alfaro, JM. (2020). Characterization and Distillation of Pyrolysis Liquids Coming from Polyolefins Segregated of MSW for Their Use as Automotive Diesel Fuel. Energy & Fuels. 34(5):5969-5982. https://doi.org/10.1021/acs.energyfuels.0c00403S59695982345Al-Salem, S. M., Lettieri, P., & Baeyens, J. (2009). Recycling and recovery routes of plastic solid waste (PSW): A review. Waste Management, 29(10), 2625-2643. doi:10.1016/j.wasman.2009.06.004Hestin, M.; Faninger, T.; Milios, L. 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Characterization of pyrolysis products from end-of-life electronic equipment

Tertiary Recycling of End-of-Life electronic equipment such as computer monitor casings and disk drives is considered in this project. This research aim\u27s at finding new recycling processes that have a possibility for economic scale-up. The present work was divided into two parts. The first one dealt with the investigation of two mixed-plastics streams provided by MBA Polymers (MBAP). One of the streams consisted of fines (MBAP-1), and the other was a non-separable stream, MBAP-2. These solid polymer streams from MBAP were reacted in a Tubular Reactor inerted with helium. The overall objective of these reactions is to determine the process parameters (Reaction Temperature and Pressure) required in order to achieve maximum oil yield. The reaction process parameters are the reaction temperature (375°C, 400°C, 425°C and 450°C) and the reaction time (15min, 30min and 45min). Tetrahydrofuran (THF) and hexane are used as solvents to separate the non-gaseous products which are partitioned into THF-Insoluble, THF-Soluble Hexane-Insoluble and Hexane-Solubles while the gaseous products are analyzed using a gas chromatograph (GC). (Abstract shortened by UMI.)

Catalytic Conversion Of Crop Oil To Petrochemical Substitutes And Other Bio-Based Chemicals

A two-step process was developed for the production of aromatic hydrocarbons from triacyl glyceride (TG) oils such as crop oils, algae oils, and microbial oils. In the first step, TG (soybean) oil was non-catalytically cracked to produce an organic liquid product (OLP). The resulting OLP was then converted into aromatic compounds in a second reaction using a zeolite catalyst, HZSM-5. In this second reaction three main factors were found to influence the yield of aromatic hydrocarbons, namely the SiO2:Al2O3 ratio in the HZSM-5, the reaction temperature and the OLP-to-catalyst ratio. Upon optimization, up to 58 wt% aromatics were obtained. Detailed analyses revealed that most of the alkenes and carboxylic acids, and even many of the unidentified/unresolved compounds which are characteristic products of non-catalytic TG cracking, were reformed into aromatic hydrocarbons and n-alkanes. Instead of BTEX compounds that are the common products of alkene reforming with HZSM-5, longer-chain alkylbenzenes dominated the reformate (along with medium-size n-alkanes). Another novel feature of the two-step process was a sizable (up to 13 wt%) yield of alicyclic hydrocarbons, both cyclohexanes and cyclopentanes. At optimum conditions, the yields of coke (5 wt%) and gaseous products (14 wt%) were found to be lower than those in a corresponding one-step catalytic cracking/aromatization process. Thus this novel two-step process may provide a new route for the production of renewable aromatic hydrocarbons. Aromatization of propylene was performed in a continuous reactor over HZSM-5 catalysts. A full-factorial design of experiments (DOE) methodology identified the effects of temperature (400-500 °C), Si:Al ratio (50-80), propylene feed concentration (8.9-12.5 mol%), and catalyst amount (0.2-1.0 g) on propylene conversion as well as the yields of benzene, toluene, p-xylene, o-xylene (BTX), and total BTX. The Si:Al ratio and amount of the HZSM-5 catalyst influenced all of the responses, while temperature impacted all the responses except the yield of p-xylene. An increase in feed concentration significantly increased the yields of benzene, toluene, and total BTX. An interaction between propylene feed concentration and catalyst amount influenced the yields of benzene, toluene, and total BTX. This interaction indicated that a higher feed concentration promotes aromatization at higher catalyst concentrations. By contrast, the interaction of Si:Al ratio with propylene feed concentration was found significant for p-xylene and o-xylene yields, but not for benzene and toluene, suggesting that xylenes are synthesized on different sites than those for benzene and toluene. These interaction effects demonstrate how the use of DOE can uncover significant information generally missed using traditional experimental strategies. The catalytic conversion of propylene to BTX (benzene, toluene, xylenes) over nanoscale HZSM-5 zeolite was studied. A full-factorial design of experiments (DOE) methodology identified three factors which significantly affected the aromatization process: temperature (400-500 °C), propylene feed concentration (8.9-12.5 mol%), and catalyst amount (0.2-1.0 g). An increase in all three factors significantly increased the yields of benzene, toluene, and total BTX but decreased the yield of xylene. A DOE method was used to determine significant interaction effects which may be missed using parametric experimental strategies. The observed effects showed that nanoscale HZSM-5 catalyst is better suited for facilitating cracking rather than aromatization reactions presumably due to the smaller pore availability compared to micro-sized zeolites. Select experiments in a batch reactor with soybean oil as a feedstock showed that the nanoscale zeolite strongly retained large amounts of water, presumably within its pores, despite prior high temperature calcinations

Effect of blending on fuel gas composition of pyrolysed plastic wastes

An investigation into the effects of blending on the gaseous product distribution of plastic wastes was carried out. Waste Low Density Polyethylene (LDPE) and waste High Density Polyethylene (HDPE) samples were subjected to thermal pyrolysis in an electric tubular furnace. First, the effect of heating rate on the volume of the gaseous products was studied. Heating rate values of 22oC/min, 26oC/min and 32oC/min were used with results showing that a higher heating rate favoured the production of non-condensable gases in HDPE but caused a persistent decrease in LDPE. The investigation into the effects of blending was then carried out at a temperature range of 480oC – 600oC and heating rate of 22oC/min using blends of 0%, 20%, 40%, 50%, 60%, 80% and 100% LDPE in HDPE. The gaseous product was analysed by gas chromatography and results obtained showed a similarity in hydrocarbon product distribution for both LDPE and HDPE gas products. 100% LDPE showed a composition of 21.84%, 47.39%, 20.78%, 8.40%, and 1.59%; and 100% HDPE showed a composition of 18.88%, 46.91%, 22.89%, 9.59%, and 1.73% for C1, C2, C3, C4, and C5+ hydrocarbon molecules respectively. The presence of LDPE in blends of LDPE-HDPE favoured the production of C1 up to 99 mol. %.Keywords: pyrolysis, waste plastics, LDPE, HDPE, fuel ga

Sampling of Gas-Phase Intermediate Pyrolytic Species at Various Temperatures and Residence Times during Pyrolysis of Methane, Ethane, and Butane in a High-Temperature Flow Reactor

Air pollution in many major cities is endangering public health and is causing deterioration of the environment. Particulate emissions (PM) contribute to air pollution as they carry toxic polyaromatic hydrocarbons (PAHs) on their surface. Abatement of PM requires continuous strict emission regulation and, in parallel, the development of fuels with reduced formation of PM. Key processes in the formation of PM are the decomposition of hydrocarbon fuels and the synthesis of potential precursors that lead to the formation of benzene rings and thereafter growth to PAHs and eventually PM. Methane, ethane and butane are important components of natural gas and liquefied petroleum gas, and are also widely used in transportation, industrial processes and power generation. This paper reports on a quantitative investigation of the intermediate gaseous species present during pyrolysis of methane, ethane and butane in a laminar flow reactor. The investigation aimed to further the understanding of the decomposition process of these fuels and the subsequent formation of aromatic rings. The pyrolysis of methane, ethane and butane were carried out in a tube reactor under laminar flow conditions and within a temperature range of 869–1213 °C. The fuels were premixed in nitrogen carrier gas at a fixed carbon atom concentration of 10,000 ppm, and were pyrolysed under oxygen-free conditions. Intermediate gaseous species were collected from within the tube reactor at different residence times using a specially designed high-temperature ceramic sampling probe with arrangements to quench and freeze the reactions at entry to the probe. Identification and quantification of intermediate species were carried out using a gas chromatography-flame ionization detector (GC-FID). During methane pyrolysis, it was observed that as the concentration of acetylene increased, the concentration of benzene also increased, suggesting that the benzene ring is formed via the cyclo trimerisation of acetylene. With all three fuels, all intermediate species disappeared at higher temperatures and residence times, suggesting that those species converted into species higher than benzene, for example naphthalene. It was observed that increasing carbon chain length lowered the temperature at which fuel breakdown occurred and also affected the relative abundance of intermediate species

Pyrolysis and catalytic cracking of municipal plastic waste for recovery of gasoline range hydrocarbons

Plastic is an indispensable part of our daily life. Its production and consumption has been rising very rapidly due to its wide range of application. Due to its non biodegradable nature it cannot be easily disposed off. So, nowadays new technology is being used to treat the waste plasic. One of such process is pyrolysis. This paper describes non catalytic pyrolysis and catalytic cracking of plastic wastes into useful gasoline range hydrocarbons. Under the pyrolytic and cracking conditions the plastic wastes can be decomposed into three fractions: gas, liquid and solid residue. Here the main consideration is the recovery of liquid products which are composed of higher boiling point hydrocarbons. The waste plastics consisting of high density polyethylene (HDPE) was pyrolyzed in this study. Pyrolysis appears to be a technique that is able to reduce a bulky, high polluting industrial waste while producing energy and/or valuable chemical compounds. The pyrolysis of plastic wastes produces a whole spectrum of hydrocarbons including paraffins, olefins, naphthalenes and aromatics. By catalytic cracking more aromatics and naphthene in the range of C6-C8 which are valuable gasoline range hydrocarbons can be produced. Different catalysts like Silica Alumina, Modernite and Activated Carbon were used for catalytic cracking. The catalysts were used in different ratios with feed to find out the optimum range at which maximum yield occurs. The liquid product yield is about 60% in all the cases. In thermal pyrolysis, the product obtained gets solidified but in catalytic cracking good liquid product can be obtained which can be used as fuel. This application is further combined with technologies of municipal plastic wastes collection, classification and pretreatment at front end and product purification and testing at back end to determine the properties of the various products obtained