Waste Plastic Mixture Research Articles

Equilibrium model analysis of waste plastics gasification using CO2 and steam.

Utilization of carbon dioxide (CO2) in thermochemical treatment of waste plastics may significantly help to improve CO2 recycling, thus simultaneously curtailing dioxins/furans and CO2 emissions. Although CO2 is not such an effective gasifying agent as steam, a few investigations have explored the utilization of CO2 in conjunction with steam to achieve somewhat higher carbon conversion. This work presents a comparative evaluation study of CO2 and steam gasification of a typical post-consumer waste plastics mixture using an Aspen Plus equilibrium model. The effect of flow rate of gasifying medium (CO2 and/or steam) and gasification temperature on product gas composition, carbon conversion, and cold gas efficiency has been analyzed. Simulation results demonstrate that CO2 can serve as a potential gasifying agent for waste plastics gasification. The resulting product gas was rich in CO whereas CO2-steam blends yield a wider H2/CO ratio, thus extending the applications of the product gas.

Fe–Ni–MCM-41 Catalysts for Hydrogen-Rich Syngas Production from Waste Plastics by Pyrolysis–Catalytic Steam Reforming

A two-stage pyrolysis–catalytic steam reforming process was used with mesoporous MCM-41 supported iron and nickel bimetallic catalysts for hydrogen-rich syngas production from a simulated mixture of waste plastics. Different Fe/Ni weight ratios (00:20, 05:15, 10:10, 05:15, and 20:00) have been investigated to determine the influence on hydrogen production. The results showed that the presence of Fe and Ni together produced a synergistic enhancement of the total gas yield and hydrogen and carbon monoxide production. For example, the (10:10) Fe–Ni–MCM-41 catalyst produced the highest gas yield of 95 wt %, the highest H2 production of 46.1 mmol H2 g–1plastic, and the highest CO production at 31.8 mm g–1plastic. The (10:10) Fe–Ni–MCM-41 catalyst produced a volumetric hydrogen concentration of 46.7 vol %, and carbon monoxide was 32.2 vol %. The (10:10) Fe–Ni–MCM-41 catalyst also showed the lowest carbon deposition on the catalyst. The carbon deposits were mainly of the amorphous encapsulating type for the iron...

Thermocatalytic Conversion of Automotive Shredder Waste and Formation of Nanocarbons as a Process Byproduct

Thermocatalytic conversion of plastic wastes using titanium dioxide (TiO2) is a novel and promising approach for waste management and sustainable production of materials. In this approach, the heat-treatment of a mixture of plastic waste and TiO2 at elevated temperatures helps to achieve fast and complete decomposition and offers several advanced byproducts. In this study, the different physicochemical interactions between TiO2 and an industrial plastic waste (i.e., automotive shredder residue, ASR) at elevated temperatures were investigated. The nonisothermal degradation kinetics of ASR, with and without TiO2, were calculated from the thermogravimetric analysis (TGA) and results confirmed that the TiO2 influences and catalyzes the degradation of ASR. The analysis of the resulting gas showed that the TiO2 limits the formation of CO2 gas, which is considered an unfavorable product of thermal processes, without changing the quality of the hydrocarbons (i.e., oils) generated during the heat treatment of ASR. While ASR decomposes, TiO2 transforms into value-added Ti-based ceramics; this transformation generates a high yield of CO that can be collected for commercial purposes. In addition, TiO2 led to the formation of considerable quantities of onion-like carbon nanoparticles (OLC-NPs) from the gas phase; this product was characterized and its formation mechanism was discussed.

Polymer Recovery through Selective Dissolution of Co-mingled Post-Consumer Waste Plastics

It still remains a challenge to the recycling industry to develop an efficient and economical large-scale plastic waste recycling system, in spite of growing environmental concerns in waste disposal. Selective dissolution and precipitation (SDP) is a mechanical recycling technique that eliminates pre-sorting of mixed waste plastics and recycling polymer of high-grade quality. In this preliminary investigation, recycling of a comingled post-consumer waste plastic mixture of low-density polyethylene (LDPE), polystyrene (PS), high-density polyethylene (HDPE), and polyethylene terephthalate (PETE) using a lab-scale SDP setup was examined. A few experimental runs performed on the representative samples using Xylene/Toluene as solvents and acetone/2-propanol as anti-solvents demonstrated the sorting and recycling efficiency of this technique. FT-IR analysis of the reclaimed products revealed that the structural properties being very similar to virgin materials.

8-3.含塩素廃プラスチックの高度塩素除去((1)クリーン燃焼・CO_2回収技術,Session 8 環境対策・リサイクル)

8-3.含塩素廃プラスチックの高度塩素除去((1)クリーン燃焼・CO_2回収技術,Session 8 環境対策・リサイクル)

Core/shell morphologies in recycled poly(ethylene terephthalate)/linear low-density polyethylene/poly(styrene-b-(ethylene-co-butylene)-b-styrene) ternary blends

Compatibilizer plays very important roles in preparing high performance polymer composites, not only for the ternary immiscible polymer blends, but also for the recycled and reused of waste plastics mixture. Generally, the compatibilizers can be used as the toughening agent in blending polymer materials. In the present work, the poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) or maleic anhydride-grafted poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS-g-MA) acts as the compatibilizer and toughening agent for the preparation of R-PET/LDPE/SEBS (70/20/10) ternary blends. It must be pointed that the ternary blends are costlessly and conveniently prepared from the recycled poly(ethylene terephthalate) (R-PET) and linear low density polyethylene (LLDPE) through a melt blending in a co-rotating twin-screw extruder and injection moulded. The morphologies of the ternary blends are characterized by scanning electron microscopy (SEM). It was found that the blends contains reactive or non-reactive compatibilizer, the morphology originates from the LLDPE particles encapsulated by both SEBS and SEBS-g-MA. So, it results to the reduced interfacial tension between of the R-PET and SEBS-g-MA, in which the grafted chains of PET-g-SEBS-g-MA formed through in situ reaction between R-PET and SEBS-g-MA phases. Therefore, core–shell particles with smaller diameter disperse uniformly in the blends. Moreover, the good compatibilization and corresponding morphologies induce in balanced mechanical and thermal properties. DSC analysis show the dispersed phase particles could act as nucleating agent in the R-PET matrix, which results the improvement of the crystallization temperature. And it was also observed the decreased nucleation activity in graft copolymers in the R-PET/LLDPE/SEBS-g-MA blends. Notched Charpy impact strength and elongation at break are improved by the addition of compatibilizer.

Reforming and Desulphurization of Syngas by 3D-printed Catalyst Carriers

Sulfur and CH4 are two important ingredients in synthesized gaseous fuels and they must be removed before use in solid oxide fuel cells. This study compares the gasification of mixtures of waste paper and plastics and with that for wood. The produced fuel (syngas), which is rich in H2, CH4 and CO, is reformed and desulfurized using stacks of 3D-printed catalyst carriers, which are made using thee ceramic powders (ZnO, θ-Al2O3, and CaCO3). The pyramid-shaped carrier features high porosity (50%) and good strength (ca. 6 MPa). It carries fine-grain Ni+CeO2 catalyst and increases the retention of the syngas. The performance of the thee carriers is determined with respect to the gas content (including H2, CH4, CO and H2S) in the syngas.

Morphology development and superior mechanical properties of PP/PA6/SEBS ternary blends compatibilized by using a highly efficient multi-phase compatibilizer

Multi-phase compatibilizers are potentially attractive, not only for the preparation of ternary or multi-phase immiscible polymer blends with high performance, but also for recycling and reuse of waste plastics mixture. In this study, the maleic anhydride (MAH) and styrene (St) dual monomers grafted PP, PP-g-(MAH-co-St) is prepared as a multi-phase compatibilizer, which exhibits highly effective compatibility on the PP/PA6/SEBS (70/15/15) ternary blends. Scanning electron microscopy (SEM) reveals that, with increasing the compatibilizer, the morphology evolves from the individual PA6 particle encapsulated by SEBS to several smaller-size PA6 particles partially encapsulated by SEBS phase, then to the tiny PA6 particles and some larger-size SEBS agglomerates predominantly dispersed separately in PP matrix. The morphology development predicted by spreading coefficients shows a consummate consistency with that observed by SEM. Moreover, the good compatibilization and corresponding morphologies result in superior enhancement of mechanical properties. Compared to the uncompatibilized blend, adding 15 wt% multi-phase compatibilizer to the blend leads to the best mechanical properties with the yield stress, stress at break, strain at break and impact failure energy improved significantly by 23%, 132%, 647% and 220%, respectively. The results verify that the domains with small-size PA6 particles (0.3–0.4 μm) partially encapsulated by SEBS (0.5–0.7 μm) in PP matrix are very effective to enhance the mechanical properties of the blends. The morphologies of large-size PA6 particles encapsulated by SEBS or tiny PA6 particles and some larger-size SEBS agglomerates dispersed separately in PP matrix for the enhancement in mechanical properties of the blends are very limited. Consequently, the enhanced interfacial interactions and the morphology with the rigid particles partially encapsulated by a rubber-like phase in matrix are crucial for the ternary polymer blends.

Manipulating the H2/CO ratio from dry reforming of simulated mixed waste plastics by the addition of steam

Two-stage pyrolysis-catalytic reforming of plastics was investigated with the aim of producing usable quality synthesis gases (syngas) comprised of H2 and CO. The process consisted of pyrolysis of the plastics in the first stage and catalytic reforming with CO2 and steam as the reforming agents in the second stage. The plastics used were a mixture of waste plastics prepared to represent those found in municipal solid waste and the catalysts studied were Ni-Co/Al2O3 and Ni-Mg/Al2O3 prepared by the rising pH technique. A range of different CO2/steam ratios were considered; 4:0, 4:0.5, 4:1, 4:1.5 and 4:2 for the Ni-Co/Al2O3 catalyst and 4:0, 4:0.5, 4:1, 4:2 and 4:3 for the Ni-Mg/Al2O3 catalyst. The results obtained demonstrated that the catalysts and the CO2/steam ratio influence the syngas quality, as represented by the H2/CO molar ratio value. With the Ni-Co/Al2O3 catalyst, the H2/CO molar ratio was increased from 0.74 (no steam) to 0.94 (CO2:steam ratio; 4:1) however the H2/CO molar ratio decreased with further steam addition. Results using the Ni-Mg/Al2O3 catalyst showed a different trend, wherein the H2/CO molar ratio increased with the increase of steam addition into the system. From the evaluation of the gas composition, the steam addition with the Ni-Mg/Al2O3 catalyst promoted hydrogen production while the Ni-Co/Al2O3 catalyst promoted carbon monoxide production. The addition of steam to the dry reforming of waste plastics has the potential to manipulate the H2/CO molar ratio hence, the quality of syngas produced can be matched to the desired end-use industrial application.

Pyrolysis-Catalytic-Dry Reforming of Waste Plastics and Mixed Waste Plastics for Syngas Production

The CO2 dry reforming of various types of waste plastics (LDPE, HDPE, PS, PET, and PP) and a simulated mixture of the different waste plastics was investigated over a Ni–Co–Al catalyst using a two-stage reactor. The first stage pyrolyzed the plastics, and the second stage involved catalytic-dry reforming of the product pyrolysis gases with CO2. The introduction of CO2 without a catalyst markedly increased the dry reforming reaction and significantly improved the production of H2/CO synthesis gas (syngas). The introduction of the Ni–Co–Al catalyst further significantly improved the production of syngas. LDPE produced the highest yield of syngas at 154.7 mmolsyngas g–1plastic from the pyrolysis-catalytic-dry reforming process. The order of syngas production for the different plastics was LDPE < HDPE < PP < PS < PET. The syngas yield from the processing of the simulated waste plastic mixture was 148.6 7 mmolsyngas g–1plastic which reflected the high content of the linear polyalkene plastics (LDPE, HDPE, PP) ...

Temperature and time influence on the waste plastics pyrolysis in the fixed bed reactor

Pyrolysis as a technique of chemical recycling of plastic materials is causing an increasing level of interest as an environmentally and economically acceptable option for the processing of waste materials. Studies of these processes are carried out under different experimental conditions, in different types of reactors and with different raw materials, which makes the comparison of different processes and the direct application of process parameters quite complex. This paper presents the results of investigation of the influence of temperature in the range of 450°C to 525°C, on the yield of the process of pyrolysis of waste plastics mixture, composed of 45% polypropylene, 35% low density polyethylene and 25% high density polyethylene. Also, this paper presents results of the investigation of the effect of the reaction, atintervals of 30-90 [min], on the yield of pyrolysis of the mentioned waste plastics mixture. Research was conducted in a fixed bed pilot reactor, which was developed for this purpose. The results of the research show that at a temperature of 500°C, complete conversion of raw materials was achieved, for a period of 45 [min], with a maximum yield of the pyrolysis oil of 32.80%, yield of the gaseous products of 65.75% and the solid remains of 1.46%. Afurther increase of temperature increases the yield of gaseous products, at the expense of reducing the yield of pyrolysis oil. Obtained pyrolysis oil has a high calorific value of 45.96 [MJ/kg], and in this regard has potential applications as an alternative fuel.

Impacts of Different Wetting Agents on the Density Separation of Waste Plastic Mixtures

As the effect of density separation for waste plastic mixtures was poor, this research studied the impacts of wetting agents on the sorting rates of waste plastic mixtures and the mechanisms of wetting agents in density separation. The results showed that the surface activity of plastics could be changed by wetting agents and thus the sorting rates of plastics under the density separation system could be improved. Impacts of wetting agents such as CaLS, NP-7 and MC on density separation of plastics are related not only to the molecular structure of plastic materials but also to the separating media. The density separation system in the presence of different wetting agents established in this research separated the target plastic with a rate of 100%, which applied to a mixture of 9 kinds of common plastics such as PVC, PC, PS and so on.

Effect of binary mixture of waste plastics on the thermal behavior of pyrolysis process

Waste plastic is non‐biodegradable material that does not decompose naturally for a long time. The pyrolysis process is a reliable method to decompose plastic wastes, which involves breaking of the heavy carbon chains and convert to light hydrocarbons. The light hydrocarbon products can be used as fuel to power vehicles and power stations. Pyrolysis experiment was conducted using thermogravimetric analysis (TGA)/DSC equipment for different types of non‐recyclable waste plastics: PET, HDPE, LDPE, PP, PS foam, and PS rigid. Investigations have been done to study the effect of binary mixture composition of PP and HDPE on pyrolysis behavior. Interactions between the plastics have been found to occur at the mixture composition range of 20–80 wt %. The decomposition rates of the individual plastics enhanced after the binary mixing of the different types of plastics. It was also found that secondary reaction occurred when mixing two types of plastics. The activation energy of the first step pyrolysis reaction is also higher than the secondary reaction. Overall, the activation energy of the pyrolysis reaction is decreased by 55% at the range of 20–80 wt % of binary mixture composition. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1113–1119, 2015

Conversion of Hazardous Motor Vehicle Used Tire and Polystyrene Waste Plastic Mixture into useful Chemical Products

Motor vehicle used tire and polystyrene waste plastic mixture into fuel recovery using thermal degradation process in laboratory batch process. Motor vehicle used tire and polystyrene waste plastic was use 75 gm by weight. Motor vehicle tire was 25 gm and polystyrene waste plastic was 50 gm. In presence of oxygen experiment was performed under laboratory fume hood. Thermal degradation temperature range was 100 - 420 oC and experiment run time was 5 hours. Product fuel density is 0.84 gm/ml and liquid fuel conversion rate was 54.93 %. Fuel was analysis by GC/MS and compounds are present aliphatic group, aromatic group, alcoholic group, oxygen content and nitrogen content. Fuel can use refinery process as a refinery feed. Keywords: Tire, polystyrene, conversion, chemical product, vehicle, hydrocarbon

The Effect of Natural Clays Catalysts on Thermal Degradation of a Plastic Waste Mixture

The thermal and catalytic degradation of a plastic wastes mixtures using two types of natural clays catalysts has been carried out in order to obtaining liquid oils with potential use in the chemical industry. Thus, the polymer waste mixture (PWM) of polystyrene (PS), poly (ethylene terephthalate) (PET) and poly (vinyl chloride) (PVC) were thermally degraded at 420 °C in absence and presence of studied catalysts in mass ratio 1:10, catalyst/PWM. The catalysts were characterized by N2 adsorption-desorption isotherms (BET), Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectrometry (FTIR) for determined the structural and textural properties. The degradation of plastic wastes produces gases, liquids and solid residue products. The effect of the catalyst types on the yields and distribution of end-products obtained by thermal and catalytic degradation of mixed plastic waste has been studied. The yields of liquid oils fractions were calculated between 54.98 wt.% and 62.18 wt.%. The liquids and solid products were analyzed by different analytical techniques: gas chromatography mass spectrometry (GC-MS), ultraviolet visible spectroscopy (UV-Vis) and/or FTIR, in order to establish the chemical compositions. The GC-MS results showed that the liquid products contain in principal monoaromatic compounds like styrene, toluene, ethylbenzene or α-methylstyrene. The FTIR and UV-Vis spectra of products indicated the specific vibration bands or transitions between electronic energy levels of the functional groups of the constituent compounds.

Thermal Conversion of Waste Plastics (HDPE, PP and PS) to Produce Mixture of Hydrocarbons

Thermal conversion process was applied with three types of waste plastic mixture and waste plastics mixture to liquid hydrocarbon fuel production in present of o xygen under laboratory Labconco fu me hood without adding any kind of catalyst. Utilization of the process described can reduce the impact of waste plastics significantly. Thermal decomposition of the most co mmon plastics such as high density polyethylene (HDPE), polypropylene (PP) and polystyrenes (PS) has been conducted to produces a mixture of hydrocarbons. The thermal process applied of mixed waste plastics using a steel reactor at 25- 430℃ has been investigated. The reactor was connected with standard condensation unit with water circulator system. Waste plastics are broken down into shorter chain hydrocarbon compounds from long chains during the thermal conversion process without adding catalyst or chemical. Produced fuel was analysis by using GC/M S, FT-IR and DSC and fro m GC/MS analysis result showed hydrocarbon chain range C3 to C28 into fuel and produce fuel can be use as feed stock refinery or power plant for electricity generation or can use for internal co mbustion engine.

Retention of mercury by low-cost sorbents: Influence of flue gas composition and fly ash occurrence

The present study employs chars obtained from the gasification of different types of biomass as low cost sorbents of mercury at laboratory scale. The influence of gas composition and fly ash occurrence on mercury retention and oxidation by char samples was evaluated. Chars obtained from a mixture of paper and plastic waste showed mercury retention capacities similar to those obtained with a commercial activated carbon. Homogeneous mercury oxidation was mainly promoted by NO2 and, to a certain extend, by SO2+O2. The highest heterogeneous mercury oxidation was observed in the chars with the highest mercury retention capacity suggesting that the sorption process also involves the capture of oxidized mercury species. The presence of fly ash particles clearly influenced heterogeneous oxidation but did not affect mercury retention by the char sorbents.

Energy Recovery from Municipal Solid Waste by Briquetting Process: Evaluation of Physical and Combustion Properties of the Fuel

This study presents an experimental production of solid waste briquettes from municipal solid waste by screw extrusion technology and piston press technology. Combustible matters present in municipal solid wastes like paper, plastic and biomass (represented by rice husk) were processed using grinders and shredders and then densified. Two varieties of Refuse derived fuel were subjected to heat (around 300 0C) in Screw Extrusion machine while seven varieties of Selective fuel in the composition 0-70% lignite and 5-30% polyethylene by weight were densified at a constant pressure of 3.12 tons/cm2 at room temperature in piston press briquetting machine. Lime was added to one variety to capture emissions during fuel combustion. The production and analysis of the fuel briquettes were carried out according to Japanese Industrial Standards (JIS 8811, 8812) in the Biomass laboratory of NAST at Khumaltar. It was observed that addition of waste plastic improves fuel quality of low grade coal (lignite). High temperature and high pressure is required for briquetting the mixture of plastic and paper waste. The produced fuel briquettes might be suitable for use in industrial boilers and brick kilns but suitable control measures should be applied to capture harmful emissions.DOI: http://dx.doi.org/10.3126/njst.v12i0.6508 Nepal Journal of Science and Technology 12 (2011) 238-241

Biomass gasification chars for mercury capture from a simulated flue gas of coal combustion

The combustion of coal can result in trace elements, such as mercury, being released from power stations with potentially harmful effects for both human health and the environment. Research is ongoing to develop cost-effective and efficient control technologies for mercury removal from coal-fired power plants, the largest source of anthropogenic mercury emissions. A number of activated carbon sorbents have been demonstrated to be effective for mercury retention in coal combustion power plants. However, more economic alternatives need to be developed. Raw biomass gasification chars could serve as low-cost sorbents for capturing mercury since they are sub-products generated during a thermal conversion process. The aim of this study was to evaluate different biomass gasification chars as mercury sorbents in a simulated coal combustion flue gas. The results were compared with those obtained using a commercial activated carbon. Chars from a mixture of paper and plastic waste showed the highest retention capacity. It was found that not only a high carbon content and a well developed microporosity but also a high chlorine content and a high aluminium content improved the mercury retention capacity of biomass gasification chars. No relationship could be inferred between the surface oxygen functional groups and mercury retention in the char samples evaluated.

Study of the Pyrolysis Kinetics of a Mixture of Polyethylene, Polypropylene, and Polystyrene

The principal aim of this study was the identification of possible routes for the reaction mechanism of a plastic waste mixture pyrolysis. Kinetic studies of a mixture of equal percentages of polyethylene (PE), polypropylene (PP), and polystyrene (PS) were performed in order to analyze if the direct conversion of plastic wastes into gaseous, liquid, and solid products was favored, or if parallel reactions and/or reversible elementary steps should be considered. The experiments were carried out in a six microautoclave system. On the basis of the experimental results obtained at different temperatures and reaction times, a reaction pathway was proposed. The fitting of a kinetic model to the experimental data was performed. The models reasonably fit the results and gave a satisfactory explanation of several experimental data of thermal degradation of the plastic waste mixture tested. The kinetic parameters were estimated, and a dependence of the activation energy and of the pre-exponential factor on temperat...