Influence of metal‐oxide‐supported bentonites on the pyrolysis behavior of polypropylene and high‐density polyethylene

Ahmad, Imtiaz; Khan, Mohammad Ismail; Khan, Hizbullah; Ishaq, Mohammad; Tariq, Razia; Gul, Kashif; Ahmad, Waqas

doi:10.1002/app.41221

Cited by 28 publications

(13 citation statements)

References 43 publications

(53 reference statements)

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“…Summing up, the highest liquid yields described in the articles for smectite catalysts for different plastics are 100 wt% for HDPE over bentonite (50 wt%)/spent fluid catalytic cracking catalyst (FCC) [ 34 ], about 70 wt% for MDPE over acid-restructured montmorillonite catalyst [ 45 ], 87.6 wt% for LDPE over pelletized bentonite [ 8 ], 92.76 wt% for PP over Ni/acid-washed bentonite clay [ 40 ], and 88.78 wt% for PS on acid-treated bentonite-based catalyst [ 39 ]. The full conversion of the HDPE in the case of using the FCC was achieved according to step-by-step reactions where on the first step, the thermal cracking of the initial macromolecules occurred in the mesopores of the bentonite until they reached the spent FCC catalyst particles.…”

Section: Smectite Group Catalytic Activitymentioning

confidence: 99%

Thermocatalytic Conversion of Plastics into Liquid Fuels over Clays

2022

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Recycling polymer waste is a great challenge in the context of the growing use of plastics. Given the non-renewability of fossil fuels, the task of processing plastic waste into liquid fuels seems to be a promising one. Thermocatalytic conversion is one of the methods that allows obtaining liquid products of the required hydrocarbon range. Clays and clay minerals can be distinguished among possible environmentally friendly, cheap, and common catalysts. The moderate acidity and the presence of both Lewis and Brønsted acid sites on the surface of clays favor heavier hydrocarbons in liquid products of reactions occurring in their pores. Liquids produced with the use of clays are often reported as being in the gasoline and diesel range. In this review, the comprehensive information on the thermocatalytic conversion of plastics over clays obtained during the last two decades was summarized. The main experimental parameters for catalytic conversion of plastics according to the articles’ analysis, were the reaction temperature, the acidity of modified catalysts, and the catalyst-to-plastic ratio. The best clay catalysts observed were the following: bentonite/spent fluid cracking catalyst for high-density polyethylene (HDPE); acid-restructured montmorillonite for medium-density polyethylene (MDPE); neat kaolin powder for low-density polyethylene (LDPE); Ni/acid-washed bentonite clay for polypropylene (PP); neat kaolin for polystyrene (PS); Fe-restructured natural clay for a mixture of polyethylene, PP, PS, polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The main problem in using natural clays and clay minerals as catalysts is their heterogeneous composition, which can vary even within the same deposit. The serpentine group is of interest in studying its catalytic properties as fairly common clay minerals.

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Section: Smectite Group Catalytic Activitymentioning

confidence: 99%

Thermocatalytic Conversion of Plastics into Liquid Fuels over Clays

2022

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“…Zeolite catalysts were selected since their surface feature Lewis‐ and Brønsted‐acidic sites: the abstraction of a hydrogen ion from the waste polymer is initiated by the Lewis acid site, while the addition of a proton to the C−C bond is carried out by the Brønsted acid sites. Therefore, if the catalytic surface contains more Brønsted acid sites, more hydrogen is provided for the double bond [95,96] …”

Section: Pyrolysis Of Waste Plasticsmentioning

confidence: 99%

“…Therefore, if the catalytic surface contains more Brønsted acid sites, more hydrogen is provided for the double bond. [95,96] The catalysts employed for the pyrolysis of waste plastics can be applied either directly in the reaction system (in situ) or through a second reactor for the actual catalytic process (ex situ). [97] A recent study by Fan et al used continuous-stirred microwave pyrolysis (CSMP) and a batch microwave system for the pyrolysis of linear LDPE (LLDPE) in the presence and absence of HZSM-5.…”

Section: Use Of Catalystsmentioning

confidence: 99%

Recent Trends in the Pyrolysis of Non‐Degradable Waste Plastics

2021

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Waste plastics are non‐degradable constituents that can stay in the environment for centuries. Their large land space consumption is unsafe to humans and animals. Concomitantly, the continuous engineering of plastics, which causes depletion of petroleum, poses another problem since they are petroleum‐based materials. Therefore, energy recovering trough pyrolysis is an innovative and sustainable solution since it can be practiced without liberating toxic gases into the atmosphere. The most commonly used plastics, such as HDPE, LDPE (high‐ and low‐density polyethylene), PP (polypropylene), PS (polystyrene), and, to some extent, PC (polycarbonate), PVC (polyvinyl chloride), and PET (polyethylene terephthalate), are used for fuel oil recovery through this process. The oils which are generated from the wastes showed caloric values almost comparable with conventional fuels. The main aim of the present review is to highlight and summarize the trends of thermal and catalytic pyrolysis of waste plastic into valuable fuel products through manipulating the operational parameters that influence the quality or quantity of the recovered results. The properties and product distribution of the pyrolytic fuels and the depolymerization reaction mechanisms of each plastic and their byproduct composition are also discussed.

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“…The maximum yield of aromatic compounds was ~30 wt% from PP at 502 using 3 wt% Pt/C. Other catalysts, such as Pt and Rh/Al2O3 46 ) , Ga/ZSM-5 47 ) , Ru/Al2O3 48), 49 ) , Pb, Co, and Pb _ Co/BaTiO3 50 ) , Ni, Co, Fe, Mn, and Zn/AWBN (acid washed bentonite clay) 51 ) , have also been studied for the catalytic pyrolysis of the 3P.…”

Section: Pe Pp and Psmentioning

confidence: 99%

Feedstock Recycling <i>via</i> Waste Plastic Pyrolysis

Kumagai

2016

J. Jpn. Petrol. Inst.

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Plastics are essential materials for various products such as packaging and containers, electrical and electronic equipment, and automobiles. Japanese production of polymers was reported as 10.6 million t in 2014 1) , with the majority prepared from finite fossil resources. Currently, in excess of 150 and 200 different types of polymers and additives, respectively, are produced and distributed within Japan 2 ) . Metals and fillers are further mixed with these products to achieve the desired properties, giving innumerable combinations. Thus, no single recycling technique can treat all types of waste plastics. Consequently, waste plastics are commonly treated by mechanical recycling, feedstock recycling, and energy recovery, depending on the waste composition and the purpose of the recycled products.The Plastic Waste Management Institute reported that 9.3 million t of waste plastics were collected in 2014 in Japan 1 ) . The utilized rate (mechanical recycling feedstock recycling energy recovery) for collected waste plastics was 83 %, and is increasing yearly. Utilization can be broken down into 70 % energy recovery, 26 % mechanical recycling, and 4 % feedstock recycling. According to the Basic Law for Establishing the Recycling-based Society, the order of priority of these techniques is as follows: mechanical recycling feedstock recycling energy recovery. Therefore, the ideal and actual situations show a wide gap.Feedstock recycling is a growing field in Japan, but is challenging due to the mismatch with current domestic recycling systems. However, advances in research and technical development show the potential to achieve an advanced recycling-based society. In Japan, monomerization, blast furnace reduction, coke oven chemical feedstock recycling, liquefaction, and gasification are categorized as feedstock recycling. In this paper, we focus on liquefaction and gasification, which are based on the pyrolysis technique.Pyrolysis converts polymeric materials into gases, liquids, and solids at high temperatures in the absence of oxygen. This process cleaves various chemical bonds in polymers and additives by the action of only heat, which is advantageous for low-purity waste that cannot be treated by mechanical recycling. Polyethylene (PE), polypropylene (PP), and polystyrene (PS) are the main polymeric materials produced worldwide, so have been widely studied. In addition, these materials are good quality carbon and hydrogen resources (PE and PP: 86 % C and 14 % H; PS: 92 % C and 8 % H). In contrast, the pyrolysis of polyvinyl chloride (PVC) and poly(ethylene terephthalate) (PET) Recycling of waste plastics is essential for reducing environmental degradation and ensuring future resource security. The quantity of domestic plastic waste recycled is increasing yearly, reaching 83 % in 2014. However, only 26 % and 4 % of the recycled waste plastic is treated by mechanical and feedstock recycling, respectively, whereas 70 % is treated by energy recovery (incineration). Therefore, the mechanical and feedstock recycling ra...

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Influence of metal‐oxide‐supported bentonites on the pyrolysis behavior of polypropylene and high‐density polyethylene

Cited by 28 publications

References 43 publications

Thermocatalytic Conversion of Plastics into Liquid Fuels over Clays

Thermocatalytic Conversion of Plastics into Liquid Fuels over Clays

Recent Trends in the Pyrolysis of Non‐Degradable Waste Plastics

Feedstock Recycling <i>via</i> Waste Plastic Pyrolysis

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