Bidimensional ZSM-5 zeolites probed as catalysts for polyethylene cracking

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388955%3A_____%2F16%3A00467387" target="_blank" >RIV/61388955:_____/16:00467387 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1039/c5cy02075a" target="_blank" >http://dx.doi.org/10.1039/c5cy02075a</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1039/c5cy02075a" target="_blank" >10.1039/c5cy02075a</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Bidimensional ZSM-5 zeolites probed as catalysts for polyethylene cracking

Popis výsledku v původním jazyce

Lamellar and pillared ZSM-5 zeolites (L-ZSM-5 and PI-ZSM-5, respectively) were synthesized and tested in the catalytic cracking of low-density polyethylene (LDPE). The introduction of silica pillars into lamellar ZSM-5 caused a high increase in the Si/Al ratio (from 33 up to 64) and the generation of uniform mesopores with a size of about 3.5 nm. Both samples provided quite similar LDPE conversions at the three reaction temperatures investigated (340, 360 and 380 degrees C) despite the lower concentration of acid sites in PI-ZSM-5, which is assigned to the improved active centre accessibility due to the pillaring treatment. Significant activity was observed even at the lowest temperature, with LDPE conversions in the range 27-36%, which indicates that 2D ZSM-5 zeolites are convenient catalysts for polyethylene cracking. The main products of LDPE catalytic cracking were C-2-C-5 olefins with a selectivity of 60-70%, denoting that an end-chain cracking mechanism is predominant. 2D ZSM-5 samples were subsequently compared with nanocrystalline (n-ZSM-5) and hierarchical ZSM-5 (h-ZSM-5) zeolites. Pyridine adsorption followed by FTIR measurements showed significant differences in terms of not only acid site concentration but also the Bronsted/Lewis acid distribution among the samples. When the LDPE cracking conversion was referred to the zeolite mesopore/external surface area, a good correlation was observed with the concentration of Bronsted acid sites but not when considering just the Lewis acid sites. This interesting fact suggests that Bronsted acid sites are mainly the active centers for the cracking of the LDPE chains, concluding that in addition to the accessibility, the nature of the acid sites plays a major role in this type of reaction.

Název v anglickém jazyce

Bidimensional ZSM-5 zeolites probed as catalysts for polyethylene cracking

Popis výsledku anglicky

Lamellar and pillared ZSM-5 zeolites (L-ZSM-5 and PI-ZSM-5, respectively) were synthesized and tested in the catalytic cracking of low-density polyethylene (LDPE). The introduction of silica pillars into lamellar ZSM-5 caused a high increase in the Si/Al ratio (from 33 up to 64) and the generation of uniform mesopores with a size of about 3.5 nm. Both samples provided quite similar LDPE conversions at the three reaction temperatures investigated (340, 360 and 380 degrees C) despite the lower concentration of acid sites in PI-ZSM-5, which is assigned to the improved active centre accessibility due to the pillaring treatment. Significant activity was observed even at the lowest temperature, with LDPE conversions in the range 27-36%, which indicates that 2D ZSM-5 zeolites are convenient catalysts for polyethylene cracking. The main products of LDPE catalytic cracking were C-2-C-5 olefins with a selectivity of 60-70%, denoting that an end-chain cracking mechanism is predominant. 2D ZSM-5 samples were subsequently compared with nanocrystalline (n-ZSM-5) and hierarchical ZSM-5 (h-ZSM-5) zeolites. Pyridine adsorption followed by FTIR measurements showed significant differences in terms of not only acid site concentration but also the Bronsted/Lewis acid distribution among the samples. When the LDPE cracking conversion was referred to the zeolite mesopore/external surface area, a good correlation was observed with the concentration of Bronsted acid sites but not when considering just the Lewis acid sites. This interesting fact suggests that Bronsted acid sites are mainly the active centers for the cracking of the LDPE chains, concluding that in addition to the accessibility, the nature of the acid sites plays a major role in this type of reaction.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

CF - Fyzikální chemie a teoretická chemie

OECD FORD obor

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Projekt

<a href="/cs/project/GAP106%2F12%2F0189" target="_blank" >GAP106/12/0189: Dvojrozměrné zeolity s říditelnou architekturou</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Catalysis Science &Technology

ISSN

2044-4753

e-ISSN

—

Svazek periodika

6

Číslo periodika v rámci svazku

8

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

12

Strana od-do

2754-2765

Kód UT WoS článku

000374790200025

EID výsledku v databázi Scopus

2-s2.0-84971280182