Pyrolysis Of Plastic Waste Research Articles

Hydroformylation of pyrolysis oils to aldehydes and alcohols from polyolefin waste.

Waste plastics are an abundant feedstock for the production of renewable chemicals. Pyrolysis of waste plastics produces pyrolysis oils with high concentrations of olefins (>50 weight %). The traditional petrochemical industry uses several energy-intensive steps to produce olefins from fossil feedstocks such as naphtha, natural gas, and crude oil. In this work, we demonstrate that pyrolysis oil can be used to produce aldehydes through hydroformylation, taking advantage of the olefin functionality. These aldehydes can then be reduced to mono- and dialcohols, oxidized to mono- and dicarboxylic acids, or aminated to mono- and diamines by using homogeneous and heterogeneous catalysis. This route produces high-value oxygenated chemicals from low-value postconsumer recycled polyethylene. We project that the chemicals produced by this route could lower greenhouse gas emissions ~60% compared with their production through petroleum feedstocks.

Contaminant removal from plastic waste pyrolysis oil via depth filtration and the impact on chemical recycling: A simple solution with significant impact

Recycling of mixed plastic waste via pyrolysis and subsequent steam cracking towards light olefins is a promising solution for the ever-growing plastic waste crisis. However, the pyrolytic recycling pathway is still not established on industrial scale due to the large variety of pyrolysis oil contaminants that hamper the application in (petro-)chemical processes. In short, plastic waste pyrolysis oils are unfeasible for steam crackers without upgrading. In this work, depth filtration for the removal of particulate contamination from a post-consumer mixed polyolefin (MPO) pyrolysis oil was performed using three different filter media with different porosity. Comprehensive analyses using SEM-EDX of the retained particles as well as ICP-OES and GC × GC-FID of the filtered oils allowed to understand the efficacy of filtration. Most of the particulate contamination was removed by filtration leading to a reduction from 69 mg/L in the unfiltered sample to < 2 mg/L in the filtered samples. Particle characterization confirmed that the main contamination is composed of iron, calcium and silicon-based contaminants in combination with carbon-based species. It was confirmed by ICP-OES that after filtration, important contaminants such as nickel, vanadium and lead were reduced below contamination thresholds for steam crackers indicating that filtration is an efficient, and potentially cost-effective upgrading technique for pyrolysis oils. When steam cracking the filtered oils, results show that radiant coil coke formation was reduced by 40–60% compared to the unfiltered oil without changes in product selectivity, confirming the strong impact of particulate contamination on coke formation during steam cracking.

Ultra-low emission power generation utilizing chemically stabilized waste plastics pyrolysis oil in RCCI combustion concept

Emission standards in European Union, designed to reduce the environmental impact of power generation, present a significant challenge for fast-response distributed power generation systems based on internal combustion engines. Regulated emissions, such as NOx and particulate matter present a major concern due to their adverse number of environmental and health effects. Simultaneously, European Union strives towards sustainable management of plastic waste and seeks the ways for its upcycling and production of new fuels and chemicals. As an answer to the presented challenges, the present experimental study addresses the potential for use of chemically stabilized Waste Plastics Oil (WPO), a product of pyrolysis process of waste plastics in a Reactivity Controlled Compression Ignition (RCCI) combustion concept. To establish a reactivity-controlled combustion, the study uses a combination of methane (a model fuel for biomethane) and WPO to a) simultaneously reduce NOx and particulate matter emissions due to low local combustion temperatures and a high degree of charge homogenization and b) address waste and carbon footprint reduction challenges. Through experiments, influence of direct injection timing and energy shares of utilized fuels to in-cylinder thermodynamic parameters and engine emission response were evaluated in engine operating points at constant indicated mean effective pressure. Acquired results were deeply investigated and benchmarked against compression ignition (CI) and RCCI operation with conventional diesel fuel to determine potential for WPO utilization in an advanced low-temperature combustion concept. Results show that chemically stabilized WPO can be efficiently utilized in RCCI combustion concept without adaptation of injection parameters and that with suitable control parameters, ultra-low emissions of NOx and PM can be achieved with utilized fuels. For diesel/methane mix, NOx and PM emissions were reduced compared to conventional CI operation for 82.0% and 93.2%, respectively, whereas for WPO/methane mix, NOx and PM emissions were reduced for 88.7% and 97.6%, respectively, which can be ascribed to favourable chemical characteristics of WPO for the utilized combustion concept. In the least favourable operating point among those studied, indicated mean effective pressure covariance was kept below 2.5%, which is well below 5% being considered the limit for stable engine operation.

Catalytic microwave-assisted pyrolysis of plastic waste to produce naphtha for a circular economy

Catalytic cracking of plastics into naphtha as a substitute for new plastic production has the potential to contribute to the plastic circular economy. However, mitigating catalyst deactivation in large-scale processes poses a significant challenge. Here, we demonstrate a remarkable improvement (4.3 × to 12.3 ×) in catalyst lifetime by utilizing hierarchical ZSM-5 catalysts compared to conventional analogues. Increasing the Brønsted acid concentration from 0 to 302 µmol/g enhances catalyst lifetime by over 46 × and boosts cumulative aromatic selectivity from 6 to 73%. Catalyst characterization reveals the development of significant voids after modification, enhancing molecular transport within the hierarchical ZSM-5. Economic analysis shows a pilot system with a 10 ton/day capacity yielding an annual profit of $344,999 and an 11.5% return on investment. Life cycle assessment indicates a reduction of 817.6 kg CO2 eq compared to traditional plastic-to-fuels technology. These findings advance the plastic circular economy and bring us closer to commercial implementation.

Pyrolysis of plastic waste into diesel engine-grade oil

The pyrolysis of plastic waste to fuel will lead to greener waste management, ensure sustainability and serve as an alternative energy source. This study seeks to convert plastic waste into diesel engine-grade oil as an alternative energy source for various applications. A mixture of plastic waste of 58% PET, 20% HDPE, 12% LDPE, 7% PP, and 3% PS were used for the study. Catalytic and thermal pyrolysis was conducted in a batch reactor at a temperature of 450 °C for 2 h using Nitrogen gas. The plastic fuel produced was then analyzed using the Fourier Transform Infrared (FT-IR) spectroscopy and Gas Chromatography-Mass Spectrometry (GC–MS). The various characteristics of the oil, such as the kinematic viscosity, calorific value, density, and pour point, were determined. The results indicated that thermal pyrolysis produced 13% liquid, 59% gas and 27% solid residue, and on the other hand, catalytic pyrolysis yielded 15.16% liquid, 69.16% of gas, and 14.8% of solid residue. The FT-IR also showed the presence of aliphatic and aromatic compounds with a predominance of the aliphatic group. From the GC–MS analysis, the plastic fuel contains 30 compounds in the C8- C40 range. The calorific value of plastic fuel after analysis was 43.175 MJ/kg in catalytic pyrolysis and 34.132 MJ/kg in thermal pyrolysis. Also, the kinematic viscosity was 4.344 cSt in catalytic pyrolysis and 2.750 cSt in thermal pyrolysis, while the density and pour point were 0.856 g/cm3 and −17 °C respectively. These results show that catalytic pyrolysis yielded more gas and liquid with high calorific value than the thermal pyrolysis. This is an indication of the use of catalysts to improve the conversion of plastic into energy. The conversion of plastic waste into diesel oil will not only address environmental challenges but help achieve the SDGs 7 & 13 as well as Goal 7 of Agenda 2063.

Thermogravimetric catalytic pyrolysis of high-density polyethylene over iron modified chicken eggshell wastes

Among the major concerns of our current world include the accumulation of plastic wastes and the exhaustion of petroleum resources. Efforts to resolve these issues have contributed to multiple research and alternatives to be explored. One of the attractive alternatives that have been approached is the pyrolysis of plastic wastes. The use of catalysts offers multiple advantages in pyrolysis and different types of catalysts have been investigated in recent years. The potential of discarded natural wastes is acknowledged and studies to use food waste as a catalyst are to be developed in this research. The main objective of this project is to investigate the pyrolysis of high-density polyethylene (HDPE) over iron (Fe) modified waste chicken eggshell (WCE) as the catalyst. The pyrolysis was conducted at a temperature of 30 – 700℃ via a Thermogravimetric analyzer (TGA). WCE was washed, dried, and calcined in the furnace at 900℃ for 4 h. Fe was loaded (5 wt%) on the calcined WCE via the incipient wetness impregnation (IWI) method. The catalyst to HDPE mass ratio was fixed at 1:1. For comparison purposes, the commercial calcium oxide (CaO), calcined WCE, and Hydrogen exchanged Zeolite Socony Mobil − 5 (HZSM-5) were utilised in the pyrolysis of HDPE. Catalytic pyrolysis of HDPE over WCE and CaO had almost completely degraded with mass loss of 99.50% and 99.83% respectively at Phase II followed by pyrolysis of HDPE (94.05%), HZSM-5 (77.50%) and Fe/WCE (31.40%) samples. Among tested catalytic samples, the WCE catalyst works best to degrade HDPE into the highest volatile matter which attributes to higher pyrolysis oil yield.

Advancements in energy recovery from waste plastic material for sustainable environment and circular economy

Food packaging and other plastic waste measure by about 31% of global waste in terms of plastic. The major use for plastic packaging is to preserve food and make it last more and prevent it from external damages. Unfortunately, most of the plastic food packaging is used and thrown away and cannot be reused or recycled. From chocolate wrappers to chips wrappers to cloth bags, plastic packaging is used everywhere and cannot be avoided. The accumulation of waste plastic is serious threat to the environment; including pollution of the air and water and harm to wildlife and human being. One of the main reasons for the increase in plastic waste is the widespread use of disposable plastic products, such as single-use bags, bottles, and utensils. Plastic waste have a negative impact on the environment, including pollution of the air and water and harm to wildlife. Pyrolysis is one of the efficient methods to convert plastic waste into useful form of energy and solves these issues. The discussion in the current research include about the pyrolysis technology, important factors which affect the process parameters and utilization of plastic pyrolysis oil as a substitute of diesel. The paper also discusses about the challenges and future scope of pyrolysis of waste plastic.

Experimental investigation on slow thermal pyrolysis of real-world plastic wastes in a fixed bed reactor to obtain aromatic rich fuel grade liquid oil

Plastic wastes have become one of the biggest global environmental issues and thus recycling such massive quantities is targeted. Thermal pyrolysis has been the most suitable approach to convert the waste plastic into a source of energy. This study aims to compare the thermal pyrolysis of waste plastic with that of the modal plastic compounds in a fixed bed reactor. The liquid oil, obtained from the thermal pyrolysis of HDPE, LDPE, PP and PS wastes were characterized using FT-IR, GC-MS and 1H NMR. Also, their fuel properties such as viscosity and calorific values were characterized using parallel plate rheometer and bomb calorimeter respectively. C10–C44 paraffins and C10–C22 olefins were obtained along with aromatics and alcohols in different type of plastic waste pyrolysis oil. The viscosity of the plastic oil is within kerosene and diesel range. The calorific values of the oils are at par with the Petro fuels.

Catalytic pyrolysis of mixed plastic wastes using commercial grade kaolin and Ukpor clay from Nigeria

Catalytic pyrolysis of mixed plastic wastes using commercial grade kaolin and Ukpor clay from Nigeria

Thermal and Catalytic Pyrolysis of Real Plastic Solid Waste as a Sustainable Strategy for Circular Economy

ABSTRACT The management of plastic waste is a serious environmental problem, therefore numerous strategies have been explored to reuse/recover these materials, avoiding their disposal in landfills. In particular, research has focused on thermochemical conversion processes and especially on pyrolysis processes. Therefore, in this study, a real Plastic Solid Waste (PSW) from COREPLA (Italian national consortium for collection, recycling, and recovery of plastic packaging), deprived of PET, PVC, and PTFE was used as feedstock for batch thermal and catalytic pyrolysis tests. The experiments were performed in a micro-reactor under nitrogen flow, using ɣ-alumina as catalyst. The effects of a variation in pyrolysis temperature (450–650°C) on the gaseous, condensable, and solid products were assessed. The thermal and catalytic pyrolysis tests of LDPE at 550°C were also investigated, as a representative surrogate of the plastics materials found in PSW. Preliminary results highlight that gas and condensate yields increase with pyrolysis temperature (with or without γ–alumina). The condensate products of all experiments were an oily wax made up mainly of long-chain aliphatic hydrocarbons (mostly diesel-like fraction, C12-C20). The qualitative composition of gaseous and condensable products differs between thermal and catalytic tests. However, the alumina leads to a higher formation of aromatic hydrocarbons.

Simultaneous production of monophenol chemicals and CO2 adsorbent through salt solution-enhanced pyrolysis of electronic waste plastics

This study presented a novel method for the simultaneous generation of monophenol chemicals and carbon-based CO2 adsorbent from polycarbonate (PC) by using salt solution-enhanced pyrolysis. The regulatory functions of several factors on the production of 4-isopropenylphenol (IPP) and phenol were investigated using a laboratory-scale pyrolysis reactor, including salt solution type (neutral, acidic, and alkaline), solution concentration, and pyrolysis temperature. The results revealed that the Na2CO3 solution exhibited the best ability to enhance the preparation of IPP and phenol. At Na2CO3 concentration of 1 mol/L and pyrolysis temperature of 600 °C, the optimum yields of IPP and phenol reached 28.83 wt% and 33.77 wt%, respectively. The pyrolysis char (PCSC) obtained under this condition exhibited good CO2 adsorption behavior with a maximum adsorption capacity of 1.75 mmol/g at 30 °C because of its well-formed porous structure and copious oxygen-containing functional groups.

Catalytic Pyrolysis of Plastic Waste to Liquid Fuel Using Local Clay Catalyst

Plastics are nonbiodegradable, and safe disposal of this waste poses an environmental challenge all over the world. Catalytic pyrolysis is superior to thermal pyrolysis as it uses lower temperatures and hence less energy. The main objective of this study was to produce liquid fuel from plastic waste using indigenous clay as a catalyst through catalytic pyrolysis. The clay from Kisumu County was characterized through an X-ray fluorescence spectrometer (XRFS) and an X-ray diffractometer (XRD). The reaction setup consisted of a round-bottom flask reactor through which plastic feed and catalyst were heated in a temperature-controlled furnace. Vapor product was condensed using a Liebig type water condenser to give pyrolysis liquid product. Solid char was recovered from the flask at the end of the reaction. Optimization studies using central composite design (CCD) and response surface methodology (RSM) were performed in design expert software to predict optimal conditions of the operating variables for maximum yield of the liquid fuel. Results show that clay has a composition of silica and alumina at 64.5 wt% and 16.3 wt%, respectively, indicating high acidity of the clay, being a requirement for a good pyrolysis catalyst. For high-density polyethylene and polypropylene, the highest liquid yield of 87.23 wt% and 60.36 wt%, respectively, was at 300°C and a catalyst concentration of 10 wt%. Indigenous clay was established to be a suitable catalyst for catalytic pyrolysis of plastic waste, with the potential to replace imported catalysts since high yields of liquid fuel were obtained at lower reaction temperatures of 300-450°C, as compared to the 600°C required for thermal pyrolysis. In conclusion, waste plastics can be used to generate alternative fuel for industrial use. The liquid fuel can be used in diesel engines as a transport fuel, in turbines for electricity generation, and as a heating source in boilers and furnaces. Further studies on the modification of the surface and structure of clay are suggested to enhance its catalytic performance in the pyrolysis process for a better fuel yield.

Exploration of low heat rejection engine characteristics powered with carbon nanotubes-added waste plastic pyrolysis oil

Compression ignition (CI)-powered alternative energy sources are currently the main focus due to the constantly rising worldwide demand for energy and the growing industrialization of the automotive sector. Due to their difficulty of disposal, non-degradable plastics contribute significantly to solid waste and pollution. The waste plastics were simply dropped into the sea, wasting no energy in the process. Attempts have been made to convert plastic waste into usable energy through recycling. Waste plastic oil (WPO) is produced by pyrolyzing waste plastic to produce a fuel that is comparable to diesel. Initially, a standard CI engine was utilized for testing with diesel and WPO20 (20% WPO+80% diesel). When compared to conventional fuel, the brake thermal efficiency (BTE) of WPO20 dropped by 3.2%, although smoke, carbon monoxide (CO), and hydrocarbon (HC) emissions were reasonably reduced. As a result, nitrogen oxide (NOx) emissions decreased while HC and CO emissions marginally increased in subsequent studies utilizing WPO20 with the addition of 5% water. When combined with WPO20 emulsion, nanoadditives have the potential to significantly cut HC and CO emissions without impacting performance. The possibility of incorporating nanoparticles into fuel to improve performance and lower NOx emissions should also be explored. In order to reduce heat loss through the coolant, prevent heat transfer into the cylinder liner, and increase combustion efficiency, the thermal barrier coating (TBC) material is also coated inside the combustion chamber surface. In this work, low heat rejection (LHR) engines powered by emulsion WPO20 containing varying percentages of carbon nanotubes (CNT) are explored. The LHR engine was operated with a combination of 10 ppm, 20 ppm, and 30 ppm CNT mixed with WPO20. It was shown that while using 20 ppm of CNT with WPO20, smoke, hydrocarbons, and carbon monoxide emissions were reduced by 11.9%, 21.8%, and 22.7%, respectively, when compared to diesel operating in normal mode. The LHR engine achieved the greatest BTE of 31.7% as a result of the improved emulsification and vaporization induced by CNT-doped WPO20. According to the study's findings, WPO20 with 20 ppm CNT is the most promising low-polluting fuel for CI engines.

Investigating the influence of plastic waste oils and acetone blends on diesel engine combustion, pollutants, morphological and size particles: Dehalogenation and catalytic pyrolysis of plastic waste

Most research into the treats of plastic wastes have concentrated mainly on single-exposure pathways or products. These practices fail to acknowledge that the complications of carbon particles from engines are produced not only by diesel but by any plastic oils due to the vast amount of contaminants. With the potential to significantly weaken the impact of contaminants, the present study investigates the effects of dehalogenation and catalytic pyrolysis on plastic waste, as well as the risks associated with plastic oil blends on diesel engine. Different types of washing were conducted to effectively dehalogenate plastic waste. After pretreatment, odor compounds were analyzed using GC–MS. Subsequently, various types of pretreated plastic samples underwent catalytic pyrolysis with a 5:1 ratio of HDPE to Al2O3·2SiO2·2H2O. Differences in physico-chemical properties and hydrocarbon compounds of oils were determined. Experiments were performed using different fuel blends in a diesel engine under steady-state conditions, and their effects on combustion, emissions, morphology, and size particles were analyzed. The results show that sample B exhibited a lower toxicity level of 1,3-butadiene compared to other samples, while acetone and terpenes represented the second and third-highest emission levels in flakes, respectively. Sample C started to degrade at low temperatures (<300 °C) due to carbon addition from ethyl acetate solvent into the tertiary carbon chain of the flakes. DAP3 fuel achieved a higher reaction due to its degree of unsaturation and lower viscosity, resulting in the formation of smaller fuel droplets at high injection pressure and heat release rate (HRR). Higher emission levels were observed by DAP1 and D100, exceeding the Euro 5/6 standard limits. However, DAP3 fuel resulted in an average reduction of ∼17.14% and 21.86% in CO and smoke emissions, respectively, accompanied by a slight decrease in NOx and HC levels. Conversely, there were inconsistencies in the emission results observed with DAP2. Compared to D100, both DAP1 and DAP2 exhibited a significant accumulation and coarse particles in the PM10 forms at a peak of ∼83 nm. Whereas the DAP3 showed a smaller mobility Dp with a low nucleation particle peak, which was prone to absorb the unburned HC soot and later change to accumulation mode particles.

Assessing the economic and ecological viability of generating electricity from oil derived from pyrolysis of plastic waste in China

The increased plastic waste generation worldwide poses ponderous issues for public health and the environment. China is the highest generator of plastic waste around the world. The current treatment process (incineration) of the increased plastic waste causes dangerous environmental consequences. Pyrolysis has recently surfaced as an ecologically friendly technique for energy and material recovery from plastic waste. The present study assesses the financial and ecological viability of power production from oil derived from the pyrolysis of mixed plastic wastes in China from 2009 to 2028. The prominent findings show that the amount of plastic waste collected in 2020 (24.16 Mt) increased by 53.19% in 2028.The pyrolysis of mixed plastic wastes during the project period yielded 359.29 Mt oil, which has a power potential of 1,060.86 GWh. The economic analysis indicated the project is viable and profitable with a positive net present value (US$8.80 million) and profitability index (1.26) greater than 1. The project has 10.6 y payback period, US$0.0752/kWh levelized cost of energy, 22.5% return on investment, and 13.0% internal rate of return. The life cycle assessment results show that conversion of mixed plastic waste to pyrolysis oil for electricity generation during the project period has a total global warming potential (GWP) of 1,311.4 kt CO2eq. The GWP is mainly from conversion of pyrolysis oil to electricity (73.42%), pyrolysis oil production (15.01%) and upgrading of pyrolysis oil (11.38%). The consumption of power from the project could avoid the combustion of 2,659.0 t coal, minimizing global warming by 11,278.8 kt CO2eq. Sensitivity analysis, which examines the influence of variation in sensitive factors on the success of the project, is presented. This paper provides scientific strategies for optimal investment and decision-making on the environmental sustainability of plastic waste-to-energy pyrolysis projects.

Detailed Characterization of Chlorides and Oxides in Plastic Waste Pyrolysis Oil from Paper Mills by GC-ECD and GC-MS with Solid Phase Extraction

Identification of heteroatom compounds containing chlorine and oxygen in plastic waste pyrolysis oil (PWPO) is significant for processing. A quantitative method for 32 chlorinated hydrocarbons in PWPO was established by a gas chromatography-electron capture detector. Eight chlorinated hydrocarbons were found in PWPO, accounting for 14.0% of the total chlorine, with 1,2-dichloroethane having the highest amount. 73 compounds in the polar fraction of PWPO were identified using solid phase extraction and gas chromatography-mass spectrometry. The proportions of these compounds in the polar fraction decreased in the order of esters, nitriles, ketones, acids (including anhydride), chloroesters, phenols, alcohols, ethers, aldehydes, trienes, and siloxanes. The polar fraction contained nine chlorides. All of these chlorides were in the form of 2-chloroethyl ester, and 1,4-benzenedicarboxylic acid, di-2-chloroethyl ester, had the highest proportion among the nine chlorides. Finally, the formation pathways of 2-chloroethyl esters were illustrated. These results would provide support for the development of a clean processing technology for PWPO.

Nickel promoted Si-rich ZSM-5 nanocatalyst remarkably converts LDPE plastic waste to gasoline range hydrocarbons in a dual-bed semi-batch reactor at atmospheric pressure

Catalytic pyrolysis is an environmentally friendly recycling method, which has attracted remarkable attention due to worldwide issues of the production and accumulation of plastic wastes. In this work, the catalytic pyrolysis of Low-density polyethylene (LDPE) was carried out in a dual-bed semi-batch reactor over the Si-rich Ni/ZSM-5 nanocatalyst at atmospheric pressure. The parent nanocatalyst was prepared by hydrothermal technique and modified with nickel promoter (0–25 wt%). The properties of the nanocatalysts were characterized by XRD, FTIR, FE-SEM, EDX, TEM, BET, NH3-TPD, and TG-DTA techniques. The results showed the high crystallinity, spherical particles, and high specific surface area (376 m2g−1). The impact of operational conditions was evaluated to maximize the production of the high value-added compounds. The high percentage of the Ni promoter (25 wt%) led to the highest amount of gasoline range hydrocarbons (61%). The appropriate operational conditions were temperature of 525 °C, catalyst to plastic ratio of 1:20, and 2.5 ml min−1 nitrogen flow rate, resulting in the best product distribution: aromatics (39.4%), olefins (28.3%), and paraffins (15%). The reusability of the nanocatalyst showed high performance and more aromatic production. The characterization results of the used nanocatalyst confirmed the high stability through the pyrolysis reaction and lack of significant structural defect. The developed nanocatalyst represented the high activity through the pyrolysis of the real LDPE plastic waste, including the major product distribution in the gasoline range hydrocarbons.

Recent advances in plastic waste pyrolysis for liquid fuel production: Critical factors and machine learning applications

It is urgent to promote the technology development of plastic waste (PW) valorization to mitigate the present serious plastic pollution. Pyrolysis has been widely used to convert PW into high-value-added products, especially liquid fuels, in a sustainable manner. However, achieving a high yield of liquid fuel with good quality remains challenging due to the difficulty in optimizing pyrolysis process and synthesizing outstanding catalysts to narrow the product distribution. This work comprehensively reviewed PW pyrolysis from both technical and computational (machine learning modeling) aspects, with a critical discussion of recent challenges to find new insights for improving the conversion efficiency and promoting commercialization. Results indicated that the impacts of various factors, including PW type, process condition, catalyst, and reactor type, on the PW pyrolysis were extensively investigated by the research community. Machine learning methods have also been frequently applied to predict, interpret, and optimize the PW pyrolysis. However, more efforts can be made in the future regarding catalyst synthesis, selection of co-pyrolysis additives, mechanism of catalyst deactivation, and design of renewable energy supply system for PW pyrolysis plants. Additionally, more attention should be paid to enlarging the data size, improving model interpretability, and exploring innovative ways of machine learning application (e.g., active learning) in process optimization and catalyst design for PW pyrolysis.

Improving fuel quality from plastic bag waste pyrolysis by controlling condensation temperature

Plastic waste is a major problem in many areas around the world. The pyrolysis of plastic waste to produce fuel is another solution to this problem. But the fuel obtained from plastic waste was of low quality due to improper experimental factors. Therefore, the improvement of fuel quality in the production process is essential. This research has objective was to study the first condenser temperature in 5 levels: 10, 20, 30, 40 and 50 °C. The experimental conditions were pyrolysis temperature of 300 °C, hot filter temperature of 200 °C, second condenser temperature of -40 °C, 1 kg of plastic bag waste and the experimental period of 2 h. The results showed that the first condenser temperature of 30 °C yielded the highest first fuel yield of 70.7 wt%. When raising the temperature to 40 °C, the second fuel yield was up to 7.3 wt%. The results of the fuel properties analysis revealed that the first fuel had a high heating value (HHV) of 42.4 MJ/kg. There is a chemical composition of substances in the diesel fuel group mostly. But the first condenser temperature increased from 10 to 50 °C, causing a decrease in calorific value and density. This is a result of chemical compositions where many macromolecules are condensed in the fuel. For the analysis of the second fuel, it was found that the HHV was 38.1 MJ/kg, which was 4.3 MJ/kg lower than the HHV of the first fuel. However, the calorific value and density of the second fuel increases as the temperature of the first condenser increases. The chemical composition of the second fuels is Benzene, Toluene and Cyclononane as its main constituents, giving it a physical appearance like that of gasoline. But, in second fuels there is a chemical composition of Dicyclopentadiene. It has a clear yellow color and a pungent odor that annoys users. If in the future this substance can be eliminated, it will enable the production of fuel from plastic waste as a substitute for gasoline.

Production of combustible fuels and carbon nanotubes from plastic wastes using an in-situ catalytic microwave pyrolysis process

This study performed in-situ microwave pyrolysis of plastic waste into hydrogen, liquid fuel and carbon nanotubes in the presence of Zeolite Socony Mobil ZSM-5 catalyst. In the presented microwave pyrolysis of plastics, activated carbon was used as a heat susceptor. The microwave power of 1 kW was employed to decompose high-density polyethylene (HDPE) and polypropylene (PP) wastes at moderate temperatures of 400–450 °C. The effect of plastic composition, catalyst loading and plastic type on liquid, gas and solid carbon products was quantified. This in-situ CMP reaction resulted in heavy hydrocarbons, hydrogen gas and carbon nanotubes as a solid residue. A relatively better hydrogen yield of 129.6 mmol/g as a green fuel was possible in this process. FTIR and gas chromatography analysis revealed that liquid product consisted of C13+ fraction hydrocarbons, such as alkanes, alkanes, and aromatics. TEM micrographs showed tubular-like structural morphology of the solid residue, which was identified as carbon nanotubes (CNTs) during X-ray diffraction analysis. The outer diameter of CNTs ranged from 30 to 93 nm from HDPE, 25–93 nm from PP and 30–54 nm for HDPE-PP mixure. The presented CMP process took just 2–4 min to completely pyrolyze the plastic feedstock into valuable products, leaving no polymeric residue.