Catalytic cracking of LDPE over nanocrystalline HZSM-5 zeolite prepared by seed-assisted synthesis from an organic-template-free system

Figueiredo, Aneliése Lunguinho; Araújo, Antônio S.; Linares, María; Peral, A.; García, Rafael A.; Serrano, David; Fernandes, Valter J.

doi:10.1016/j.jaap.2015.12.005

Cited by 59 publications

(24 citation statements)

References 41 publications

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“…The information about the crystallinity of the products was estimated by the intensity ratio between the bands at 550 cm -1 and 450 cm -1 [18]. All of the band assignments were in accordance with the previous literatures [22,23]. The order of the crystallinity showed a similarity compared to that of the XRD data, as shown in Figure 2(d).…”

Section: Resultssupporting

confidence: 81%

The Surface-to-volume Ratio of the Synthesis Reactor Vessel Governing the Low Temperature Crystallization of ZSM-5

et al. 2016

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Abstract. Zeolite ZSM-5 is one of the major catalysts in the petroleum and finechemical industries. The synthesis of zeolite ZSM-5 is usually carried out at a temperature above 100 °C using an immense amount of organic structuredirecting agents (OSDA). It is interesting to note that fine-tuning the initial gel mixture can be used to enhance the typical slow crystallization rate of ZSM-5. Herein, we report the effect of the surface-to-volume ratio of the reactor vessel on the crystallization of ZSM-5 at low temperature. The surface-to-volume ratio of the reactor vessel influences the heat-transfer during the synthesis, which further governs the crystallization of ZSM-5. It was found that the higher the surface-to-volume of the reactor, the more crystalline the resulting product. The products with the highest crystallinity exhibited a nearly spherical morphology composed of smaller ZSM-5 crystallites. This phenomenon allows the presence of inter-crystallite mesopores, which is an advantage for the catalytic reaction of bulky molecules. Keywords: low OSDA; low temperature; mesopores; surface-to-volume ratio; ZSM-5. IntroductionZeolite is a class of crystalline microporous (< 2 nm) aluminosilicate materials, arranged in a long-range order by TO4 (T = Si or Al) units. Zeolite is widely known for its application in particular fields such as sorption [1], catalysis [2,3] and ion-exchange [4]. Recently, its use has been extended to wider applications, including optical [5] and membrane technology [6]. Catalysis is the most known application of zeolite, for instance ZSM-5, especially for boosting the octane number in fluid catalytic cracking (FCC) units [7]. This is due to its peculiar structure comprising straight and zig-zag channels within sizes of around 5.5 Å and the presence of strong acid sites.

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Section: Resultssupporting

confidence: 81%

The Surface-to-volume Ratio of the Synthesis Reactor Vessel Governing the Low Temperature Crystallization of ZSM-5

et al. 2016

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“…Zeolites (ZSM‐5, USY) have provided attractive results, associated with their acidic properties and porous structures . The acid sites—in particular their strength and distribution—are key parameters affecting the rate and selectivity ,,…”

Section: Figurementioning

confidence: 99%

“…In addition, the long diffusion pathways of molecules in the zeolite micropores lead to the formation of coke, therefore deactivating the catalyst. The introduction of secondary porosity to microporous ZSM‐5, also known as hierarchical zeolites, results in the shortening of the diffusion path and this increases the acid site accessibility, whereas coking is limited …”

Section: Figurementioning

confidence: 99%

Operando Study Reveals the Superior Cracking Activity and Stability of Hierarchical ZSM‐5 Catalyst for the Cracking of Low‐Density Polyethylene

et al. 2018

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A new theoretical and practical framework has been developed through operando study of the zeolite catalytic cracking of low‐density polyethylene (as a model reaction) under reaction conditions. Results show that microporous ZSM‐5 gives rise to less cracking products. Hierarchical ZSM‐5 zeolites are more active cracking catalysts, rendering more C2‐C5 hydrocarbons, with a delayed deactivation due to the secondary porosity. This tool in combination with thermogravimetric analysis provides complementary and valuable information for the study, and design of advanced catalysts.

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“…Figure 3 shows FTIR spectra (400-1800 cm −1 ) of all the catalysts. The figure shows characteristic band at 1220 cm −1 , which denotes the T-O-T asymmetric stretching mode (between TO 4 tetrahedral), typical of well-crystallized zeolites, and another band at 550 cm −1 , which denotes the asymmetric stretching mode of the five-membered rings of the pentasil ZSM-5 zeolite structure [21]. The symmetric stretching vibration of Si-O-Al framework can also be seen at wavenumbers of 450, 550, 1050 and 1200 cm −1 .…”

Section: Characterization Of the Ldpe Condensate Using Ftir And Gc/msmentioning

confidence: 99%

“…For example, in the thermal pyrolysis (Blank run), there is an increase in the non-condensable gas production from 31 to 43 wt%, while the condensates decreased from 69 to 57 wt% when the temperature increased (400-500 °C). Study has shown that as temperature increases, the cracking of the longer-chain hydrocarbon also increases [21]. Therefore, in thermal pyrolysis, the increase in temperature increases the volume of non-condensable gas and reduces the volume of the liquid fraction.…”

Section: Effect Of Temperature and Catalyst Type On The Reforming Of mentioning

confidence: 99%

Catalytic reforming of gaseous products from pyrolysis of low-density polyethylene over iron-modified ZSM-5 catalysts

et al. 2019

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Converting plastic wastes into fuels through catalytic cracking is continuously gaining interest from researchers worldwide. In this study, the influence of iron on ZSM-5 (Fe-ZSM-5) catalyst on the reforming of the gaseous products of thermal decomposition of low-density polyethylene (LDPE) was investigated. The acidified ZSM-5 catalysts (0, 0.3, 0.6 and 1 wt% of Fe) were prepared and characterized by XRD, BET, FTIR and SEM techniques. In particular, the effects of temperature (400, 450 and 500 °C) and catalyst loading (0.5, 0.75, 1.0, 1.25 and 1.5 g) on a two-stage (pyrolyser and reformer) decomposition of the LDPE wastes into fuel were studied. The liquid fraction produced was characterized using FTIR and GC/MS techniques. The study showed that the increase in pyrolysis temperature (400-500 °C) increases the volume of non-condensable gas (31-58 wt%) and decreases the volume of the condensates (69-41 wt%) in both the thermal and catalytic pyrolyses. However, the trend was at higher level for the catalytic pyrolysis. The increase in temperature for the thermal pyrolysis had less significant effect on the aromatization content of the liquid condensate compared to the catalytic pyrolysis. The FTIR results show a significant increase in aromatic contents and decrease in the aliphatic of the liquid fraction for the catalytic pyrolysis reforming when compared with thermal pyrolysis. The GC/MS results confirmed the aromatic hydrocarbon compositions, predominantly p-xylene, increased relatively to about 70% in the liquid fraction for the best catalyst (1.25 g of catalyst and 1 wt% iron loading on ZSM-5 at 450 °C).Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Catalytic cracking of LDPE over nanocrystalline HZSM-5 zeolite prepared by seed-assisted synthesis from an organic-template-free system

Cited by 59 publications

References 41 publications

The Surface-to-volume Ratio of the Synthesis Reactor Vessel Governing the Low Temperature Crystallization of ZSM-5

The Surface-to-volume Ratio of the Synthesis Reactor Vessel Governing the Low Temperature Crystallization of ZSM-5

Operando Study Reveals the Superior Cracking Activity and Stability of Hierarchical ZSM‐5 Catalyst for the Cracking of Low‐Density Polyethylene

Catalytic reforming of gaseous products from pyrolysis of low-density polyethylene over iron-modified ZSM-5 catalysts

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