Enhancing aromatics and olefins yields in thermo-catalytic pyrolysis of LDPE over zeolites: Role of staged catalysis and acid site density of HZSM-5

Fuel ◽  
2022 ◽  
Vol 314 ◽  
pp. 123071
Author(s):  
Amer Inayat ◽  
Alexandra Inayat ◽  
Wilhelm Schwieger ◽  
Barbora Sokolova ◽  
Pavel Lestinsky
2014 ◽  
Vol 16 (12) ◽  
pp. 4891-4905 ◽  
Author(s):  
Calvin Mukarakate ◽  
Michael J. Watson ◽  
Jeroen ten Dam ◽  
Xavier Baucherel ◽  
Sridhar Budhi ◽  
...  

This study investigates the role of β-zeolite acid site density on hydrocarbon and coke yields.


2016 ◽  
Vol 335 ◽  
pp. 58-61 ◽  
Author(s):  
Donghui Jo ◽  
Kyounghwan Lee ◽  
Gi Tae Park ◽  
Suk Bong Hong

2001 ◽  
Vol 40 (6) ◽  
pp. 1471-1475 ◽  
Author(s):  
P. O'Sullivan ◽  
L. Forni ◽  
B. K. Hodnett

1999 ◽  
Vol 64 (1) ◽  
pp. 168-176 ◽  
Author(s):  
Edita Rojasová ◽  
Agáta Smiešková ◽  
Pavol Hudec ◽  
Zdenek Židek

Aromatization of n-hexane over zinc-modified ZSM-5 zeolites was investigated. It was shown that incorporation of zinc by ion exchange into cationic positions of NH4-ZSM-5 zeolite causes acid-site strength redistribution and generation of new relatively strong Lewis acid sites in zeolite increasing the selectivity of n-hexane aromatization in comparison with the parent NH4-ZSM-5 zeolite. Simultaneous presence of Lewis and Broensted acid sites in ZSM-5 zeolite does not affect the strength of Broensted acid sites in zeolite. For the activity/selectivity of aromatization of n-hexane on Zn-modified ZSM-5 zeolites, the amount of Zn and its localization in the cationic positions are decisive. The reaction of n-hexane can be also initiated by the Zn species alone in the cationic positions. ZnO species alone as an extraframework phase was found inactive in the catalyst for aromatization of n-hexane. The influence of ZnO addition on the performance of pure ammonium forms of ZSM-5 zeolites in n-hexane conversion is a result of partial migration of zinc into cationic positions of zeolite by solid-state ion exchange.


2014 ◽  
Vol 233 ◽  
pp. 2-7 ◽  
Author(s):  
Yuxin Li ◽  
Yanghuan Huang ◽  
Juhua Guo ◽  
Mingye Zhang ◽  
Dezheng Wang ◽  
...  
Keyword(s):  

2003 ◽  
Vol 107 (14) ◽  
pp. 3161-3167 ◽  
Author(s):  
Filip D. P. Mees ◽  
Pascal Van Der Voort ◽  
Pegie Cool ◽  
Luc R. M. Martens ◽  
Marcel J. G. Janssen ◽  
...  

2021 ◽  
Author(s):  
Andrew Logsdail ◽  
Richard Catlow ◽  
Stefan A. F. Nastase

<div>The conversion of methanol-to-hydrocarbons (MTH) is known to occur via an autocatalytic process in zeolites, where framework-bound methoxy species play a pivotal role, especially during catalyst induction. Recent NMR and FT-IR experimental studies suggest that methoxylated zeolites are able to produce hydrocarbons by a mechanism involving carbene migration and association. In order to understand these observations, we have performed QM/MM computational investigations on a range of reaction mechanisms for the reaction of zeolite bound methoxy and carbene groups, which are proposed to initiate hydrocarbon formation in the MTH process. Our simulations demonstrate that it is kinetically unfavourable for methyl species to form on the framework away from the zeolite acid site, and both kinetically and thermodynamically unfavourable for methyl groups to migrate through the framework and aggregate around an acid site. Formation of carbene moieties was considered as an alternative pathway to the formation of C-C bonds; however, the reaction energy for conversion of a methyl to a carbene is unfavourable. Metadynamics simulations help confirm further that methyl species at the framework acid sites would be more reactive towards formed C<sub>2+</sub> species, rather than inter-framework migration and that the role of carbenes in the formation of the first –C bond will be via a concerted type of mechanism rather than stepwise. </div>


2019 ◽  
Vol 256 ◽  
pp. 117849 ◽  
Author(s):  
Linyun Chen ◽  
Xiaofang Liu ◽  
Lirong Zheng ◽  
Yongcheng Li ◽  
Xu Guo ◽  
...  

2017 ◽  
Vol 7 (17) ◽  
pp. 3831-3841 ◽  
Author(s):  
Omar A. Abdelrahman ◽  
Katherine P. Vinter ◽  
Limin Ren ◽  
Dandan Xu ◽  
Raymond J. Gorte ◽  
...  

The Brønsted acid site densities of ZSM-5, BEA and single unit cell self-pillared pentasil (SPP) zeolites of varying Si/Al ratios were measured using a new technique, reactive gas chromatography (RGC), which utilizes alkylamine decomposition to selectively count Brønsted acid sites.


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