Study on thermal stabilities and symmetries of chemisorbed species formed on K-zeolites upon CO2 adsorption by TPD and in situ IR spectroscopy

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216275%3A25310%2F18%3A39912583" target="_blank" >RIV/00216275:25310/18:39912583 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1007/s10973-017-6811-5" target="_blank" >http://dx.doi.org/10.1007/s10973-017-6811-5</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s10973-017-6811-5" target="_blank" >10.1007/s10973-017-6811-5</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Study on thermal stabilities and symmetries of chemisorbed species formed on K-zeolites upon CO2 adsorption by TPD and in situ IR spectroscopy

Popis výsledku v původním jazyce

In the current study, K-zeolites with different structure, Si/Al ratio and morphology have been prepared and then characterized by different techniques including in situ IR spectroscopy upon CO2 sorption and CO2-TPD with the aim of understanding the nature of basic sites present on their surface acting as catalytic sites in aldol condensation reaction. Results showed that depending on the zeolite structure, pore size and Si/Al ratio, two categories of basic sites could be present in potassium modified zeolites. Symmetries of chemisorbed CO2 on these sites are different and comparing the results of TPD and in situ IR spectroscopy; it can be concluded that highly symmetric species (e.g., monodentate carbonates) have higher thermal stability than low symmetric adsorbed species (e.g., bidentate carbonates). It was found that in the zeolite with relatively smaller pore size or less accessible pores (e.g., MFI), second type of adsorbed species is more popular, while highly symmetric species tend to form on large pore zeolites and on materials with some mesoporosity (e.g., BEA or dealuminated FAU zeolites). It is observed that almost all the bidentate species are desorbed at 80 A degrees C, while monodentate species are thermally stable at least up to 130 A degrees C. Based on combination of experimental data obtained from TPD with IR spectroscopy results, origin and assignment of the TPD peaks were discussed.

Název v anglickém jazyce

Study on thermal stabilities and symmetries of chemisorbed species formed on K-zeolites upon CO2 adsorption by TPD and in situ IR spectroscopy

Popis výsledku anglicky

In the current study, K-zeolites with different structure, Si/Al ratio and morphology have been prepared and then characterized by different techniques including in situ IR spectroscopy upon CO2 sorption and CO2-TPD with the aim of understanding the nature of basic sites present on their surface acting as catalytic sites in aldol condensation reaction. Results showed that depending on the zeolite structure, pore size and Si/Al ratio, two categories of basic sites could be present in potassium modified zeolites. Symmetries of chemisorbed CO2 on these sites are different and comparing the results of TPD and in situ IR spectroscopy; it can be concluded that highly symmetric species (e.g., monodentate carbonates) have higher thermal stability than low symmetric adsorbed species (e.g., bidentate carbonates). It was found that in the zeolite with relatively smaller pore size or less accessible pores (e.g., MFI), second type of adsorbed species is more popular, while highly symmetric species tend to form on large pore zeolites and on materials with some mesoporosity (e.g., BEA or dealuminated FAU zeolites). It is observed that almost all the bidentate species are desorbed at 80 A degrees C, while monodentate species are thermally stable at least up to 130 A degrees C. Based on combination of experimental data obtained from TPD with IR spectroscopy results, origin and assignment of the TPD peaks were discussed.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

<a href="/cs/project/GBP106%2F12%2FG015" target="_blank" >GBP106/12/G015: Vývoj nových nanoporézních adsorbentů a katalyzátorů</a><br>

Návaznosti

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

Rok uplatnění

2018

Kód důvěrnosti údajů

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

Název periodika

Journal of Thermal Analysis and Calorimetry

ISSN

1388-6150

e-ISSN

—

Svazek periodika

133

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

10

Strana od-do

355-364

Kód UT WoS článku

000435398700033

EID výsledku v databázi Scopus

2-s2.0-85033387355