Conversion of low-density polyethylene into monocyclic aromatic hydrocarbons by catalytic pyrolysis: Comparison of HZSM-5, Hβ, HY and MCM-41

Tian, Xiaojie; Zeng, Zihong; Liu, Zhihao; Dai, Leilei; Xu, Jiamin; Yang, Xiuhua; Yue, Linqing; Liu, Yuhuan; Ruan, Roger; Wang, Yunpu

doi:10.1016/j.jclepro.2022.131989

Cited by 51 publications

(25 citation statements)

References 28 publications

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“…This was primarily due to the large increase of C3–C5 species under MCM-41 catalysis, which promoted the occurrence of oligomerization. 19,26 In conclusion, 5% is the optimal addition ratio of MCM-41 in LDPE.…”

Section: Resultsmentioning

confidence: 85%

“…Compared with microporous catalysts such as HZSM-5 and HY, oligomers were more likely to leave the pores without structural changes. 19 In contrast, in IV, HZSM-5 essentially completely converted its product to C6–C11 species, which was close to the largest molecule (C12) that can usually be formed in the HZSM-5 pore system. 32,36 It can be seen in V that the relative content of C13–C21 species produced in III was reduced, from 25.11 wt% to 13.97 wt%; this is mainly due to the fact that oxygenated compounds in biomass can promote the bond scission of long-chain molecules of LDPE, which in turn reduced the relative content of its C13–C21 species.…”

Section: Resultsmentioning

confidence: 95%

“…3(e), when MCM-41 was not added, the carbon number distribution of the AHs produced by its pyrolysis was relatively uniform; this conformed to the law that LDPE randomly breaks at any bond in the chain under non-catalytic conditions. 19 After the addition of MCM-41, the relative content of C6–C9 was increased. This was primarily due to the large increase of C3–C5 species under MCM-41 catalysis, which promoted the occurrence of oligomerization.…”

Section: Resultsmentioning

confidence: 99%

“…6(d), the addition of the ex situ catalyst HZSM-5 (from III to IV) promoted the production of aromatics. This is mainly due to the fact that HZSM-5 has stronger Brønsted acid sites, 19 and the stronger Brønsted acid sites can easily catalyze the occurrence of continuous aromatization, resulting in a high content of MAHs, and can also easily lead to higher production of PAHs. Lewis acid sites, on the other hand, can reduce the reactivity of key carbon ions that promote the formation of aromatic compounds, thereby promoting the production of MAHs and AHs.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, FeCl 3 , which can improve the yield of furans in biomass pyrolysis, 17,18 was selected as the in situ catalyst for CAS, and the effect of its different addition ratios (0%, 3%, 5%, 7% and 10%) on the pyrolysis of CAS to furans was investigated. In addition, according to our previous study, 19 MCM-41, which can promote the production of olefins, was selected as the in situ catalyst for LDPE, and the effect of different addition ratios (0%, 3%, 5%, 7% and 10%) on the production of aromatics in a segmented co-pyrolysis system was investigated. To further investigate the synergistic effect of these two feedstocks in this system, each stage was also investigated to analyze the products of each part and the effect of an ex situ catalyst (HZSM-5) on the pyrolysis vapors from these two feedstocks.…”

Section: Introductionmentioning

confidence: 99%

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Production of monocyclic aromatic hydrocarbons by segmented in situ and ex situ two-stage coupled catalytic co-pyrolysis of biomass and waste plastics

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Production of monocyclic aromatic hydrocarbons by segmented in situ and ex situ two-stage coupled catalytic co-pyrolysis of biomass and waste plastics

et al. 2022

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Effect of the Nature, the Content and the Preparation Method of Zeolite‐Polymer Mixtures on the Pyrolysis of Linear Low‐Density Polyethylene

Arango‐Ponton,

Corjon,

Dhainaut

et al. 2024

Adv Energy and Sustain Res

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The effect of the preparation method of the mixture catalyst/polymer on the linear low‐density polyethylene (LLDPE) pyrolysis is studied by comparing the results obtained when the polymer and the catalyst (Hβ or HZSM‐5) are extruded or simply mixed in powder form. By improving the polymer/catalyst contact through extrusion, the polymer degradation took place at lower temperature. The effect of extrusion is more pronounced with Hβ compared to HZSM‐5 owing to the highest external surface of Hβ. While the yields of gas/liquid/coke do not differ with the preparation method when HZSM‐5 is used as catalyst, more significant amount of liquid phase and high production of paraffins are observed when Hβ/LLDPE mixture is extruded, according to random scission pathway reactions. The subsequent reactions are limited by the size of the pore, which impede hydrogenation reactions, producing high molecular weight molecules. Regardless of zeolite type, the micropores of the zeolite are more affected by deactivation by coke when extrusion method is used, this effect being much more important for HZSM‐5. This result is a consequence of a polymer pre‐degradation during the extrusion process in which the first cracks of the polymer at low temperature and the first pore blockages can be generated.

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Micelles Cascade Assembly to Tandem Porous Catalyst for Waste Plastics Upcycling

Feng,

Duan,

Hung

et al. 2024

Angewandte Chemie

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Catalytic upcycling of polyolefins into high‐value chemicals represents the direction in end‐of‐life plastics valorization, but poses great challenges. Here, we report the synthesis of a tandem porous catalyst via a micelle cascade assembly strategy for selectively catalytic cracking of polyethylene into olefins at a low temperature. A hierarchically porous silica layer from mesopore to macropore is constructed on the surface of microporous ZSM‐5 nanosheets through cascade assembly of dynamic micelles. The outer macropore arrays can adsorb bulky polyolefins quickly by the capillary and hydrophobic effects, enhancing the diffusion and access to active sites. The middle mesopores present a nanoconfinement space, pre‐cracking polyolefins into intermediates by weak acid sites, which then transport into zeolites micropores for further cracking by strong Brønsted acid sites. The hierarchically porous and acidic structures, mimicking biomimetic protease catalytic clefts, ideally match the tandem cracking steps of polyolefins, thus suppressing coke formation and facilitating product escape. As a result, light hydrocarbons (C1‐C7) are produced with a yield of 443 mmol·gZSM‐5‐1, where 74.3% of them are C3‐C6 olefins, much superior to ZSM‐5 and porous silica catalysts. This tandem porous catalyst exemplifies a superstructure design of catalytic cracking catalysts for industrial and economical upcycling of plastic wastes.

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Conversion of low-density polyethylene into monocyclic aromatic hydrocarbons by catalytic pyrolysis: Comparison of HZSM-5, Hβ, HY and MCM-41

Cited by 51 publications

References 28 publications

Production of monocyclic aromatic hydrocarbons by segmented in situ and ex situ two-stage coupled catalytic co-pyrolysis of biomass and waste plastics

Production of monocyclic aromatic hydrocarbons by segmented in situ and ex situ two-stage coupled catalytic co-pyrolysis of biomass and waste plastics

Effect of the Nature, the Content and the Preparation Method of Zeolite‐Polymer Mixtures on the Pyrolysis of Linear Low‐Density Polyethylene

Micelles Cascade Assembly to Tandem Porous Catalyst for Waste Plastics Upcycling

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