Effect of Enhanced Accessibility of Acid Sites in Micromesoporous Mordenite Zeolites on Hydroisomerization of n-Hexane

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388955%3A_____%2F17%3A00476873" target="_blank" >RIV/61388955:_____/17:00476873 - isvavai.cz</a>

Alternative codes found

RIV/61388980:_____/17:00476873 RIV/67985891:_____/17:00476873 RIV/00216275:25310/17:39910589

Result on the web

<a href="http://dx.doi.org/10.1021/acscatal.7b01696" target="_blank" >http://dx.doi.org/10.1021/acscatal.7b01696</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acscatal.7b01696" target="_blank" >10.1021/acscatal.7b01696</a>

Result language

angličtina

Original language name

Effect of Enhanced Accessibility of Acid Sites in Micromesoporous Mordenite Zeolites on Hydroisomerization of n-Hexane

Original language description

This paper describes a study of the nature and the accessibility of the acid sites in micromesoporous mordenite zeolites obtained by desilication and dealumination and analysis of their activity and selectivity in the hydroisomerization of n-hexane. Alkaline-acid, acid-alkaline-acid, and fluorination-alkaline-acid postsynthesis treatments were employed for the preparation of micromesoporous mordenites. The FTIR spectra of adsorbed d(3)-acetonitrille, Al-27 MAS NMR, HR-TEM, and N-2 adsorption were used for quantitative analysis of the Bronsted and Lewis sites, the coordination of Al atoms, and the textural properties. The alkaline treatment causes desilication, preferably occurring along the crystal defects and resulting in the formation of a secondary mesoporous structure characterized by 5-20 nm cavities and the formation of extraframework (Al-Ex) species and terminal Si-OH groups. The Al-Ex species formed by hydrolysis of perturbed or dislodged framework Al easily restrict part of the pseudomonodimensional channel structure of mordenite. The subsequent removal of Al-Ex by mild acid leaching or simultaneous removal of Si and Al atoms by desilication of fluorinated zeolite result in a micromesoporous structure with a large number of unrestricted channel openings and lead to a large increase in the accessibility of 01-1 groups for n-hexane. Thus, the sequential leaching treatments enable the formation of active acid sites in an environment of nonrestricted microporous channels with simultaneous enhancement of accessibility of the active sites and molecular transport. It is shown that the micromesoporous structure with high concentration of Bronsted sites of enhanced accessibility directs the hydroisomerization reaction toward high yields of branched isomers and shortening of the main 12-ring channels and that the larger numbers of channel openings result in an increase in selectivity, limiting nonselective subsequent cracking reactions.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10403 - Physical chemistry

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2017

Confidentiality

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

Name of the periodical

ACS Catalysis

ISSN

2155-5435

e-ISSN

—

Volume of the periodical

7

Issue of the periodical within the volume

9

Country of publishing house

US - UNITED STATES

Number of pages

15

Pages from-to

5781-5795

UT code for WoS article

000410005700024

EID of the result in the Scopus database

2-s2.0-85029034787