scholarly journals Measuring the Brønsted acid strength of zeolites – does it correlate with the O–H frequency shift probed by a weak base?

2014 ◽  
Vol 16 (21) ◽  
pp. 10129-10141 ◽  
Author(s):  
Carlos O. Arean ◽  
Montserrat R. Delgado ◽  
Petr Nachtigall ◽  
Ho Viet Thang ◽  
Miroslav Rubeš ◽  
...  
Keyword(s):  
Frequency Shift ◽  
Acid Strength ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Weak Base ◽  
Brønsted Acidity ◽  
Brönsted Acidity ◽  
Brönsted Acid ◽  
And Calorimetry

ΔνOH (see the figure) can be a misleading indicator of zeolite Brønsted acidity, as shown by VTIR spectroscopy and calorimetry.

Selecting strong Brønsted acid zeolites through screening from a database of hypothetical frameworks

2017 ◽  
Vol 19 (22) ◽  
pp. 14702-14707 ◽  
Author(s):  
Taku Matsuoka ◽  
Laurent Baumes ◽  
Naonobu Katada ◽  
Abhijit Chatterjee ◽  
German Sastre
Keyword(s):  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acidity ◽  
Brönsted Acidity ◽  
Brönsted Acid ◽  
Acid Zeolites

New candidate zeolites with potentially strong Brønsted acidity have been computationally selected from the Treacy/Foster database of prospective zeolites.

scholarly journals Increasing the Brønsted acidity of Ph2PO2H by the Lewis acid B(C6F5)3. Formation of an eight-membered boraphosphinate ring [Ph2POB(C6F5)2O]2

2016 ◽  
Vol 52 (73) ◽  
pp. 10992-10995 ◽  
Author(s):  
Ralf Kather ◽  
Elena Rychagova ◽  
Paula Sanz Camacho ◽  
Sharon E. Ashbrook ◽  
J. Derek Woollins ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Strong Acid ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acidity ◽  
Acid Ph ◽  
Brönsted Acidity ◽  
Brönsted Acid ◽  
Strong Lewis Acid

The strong acid (C6F5)3BOPPh2OH, was prepared in situ by the reaction of the rather weak Brønsted acid Ph2PO2H with the strong Lewis acid B(C6F5)3.

Correlation between Brønsted Acid Strength and Local Structure in Zeolites

2009 ◽  
Vol 113 (44) ◽  
pp. 19208-19217 ◽  
Author(s):  
Naonobu Katada ◽  
Katsuki Suzuki ◽  
Takayuki Noda ◽  
German Sastre ◽  
Miki Niwa
Keyword(s):  
Local Structure ◽  
Acid Strength ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid

Post-imparting Brønsted acidity into an amino-functionalized MOF as a bifunctional luminescent turn-ON sensor for the detection of aluminum ions and lysine

2019 ◽  
Vol 48 (36) ◽  
pp. 13834-13840 ◽  
Author(s):  
Yanhong Liu ◽  
Mengjie Huangfu ◽  
Pengyan Wu ◽  
Min Jiang ◽  
Xiaoli Zhao ◽  
...  
Keyword(s):  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acidity ◽  
Brønsted Acid Sites ◽  
Sensing Properties ◽  
Turn On ◽  
Brönsted Acidity ◽  
Aluminum Ions ◽  
Brönsted Acid ◽  
Brönsted Acid Sites

A MOF with amino and Brønsted acid sites, exhibiting bifunctional luminescent turn-on sensing properties for the detection of Al3+and Lys.

An ONIOM study of the distribution of skeletal aluminum and Brønsted acidity in ZSM-48 zeolite

2014 ◽  
Vol 13 (02) ◽  
pp. 1450019 ◽  
Author(s):  
Rui Liu ◽  
Jie Zhang ◽  
Xiuliang Sun ◽  
Chongpin Huang ◽  
Biaohua Chen
Keyword(s):  
Density Functional ◽  
Acid Sites ◽  
Acid Strength ◽  
Molar Ratio ◽  
Am1 Method ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Al Substitution ◽  
Brönsted Acid ◽  
Stretching Vibration

A density functional theory (DFT) study was performed on distribution of skeletal aluminum and Brønsted acid (B-acid) sites as well as the acid strength in ZSM-48 zeolite. The correlation between Si / Al molar ratio and the general acid strength was also investigated. The calculations were performed based on 51T and 90T cluster models by using two-layered ONIOM schemes (B3LYP/6-31G (d,p): AM1) method. The former 51T cluster is used for the calculation of single- Al substitution and the latter is for the multi- Al substitution study. The properties of Si / Al substitution energy, deprotonation energy, bridging hydroxyl stretching vibration frequency and adsorption energy for the probe molecule were calculated and used to measure Brønsted acid location and strength. As the result shows, T2 is the most readily to be replaced by Al and the Brønsted acids prefer to be formed at Al 2– O 7– Si 3 site. Al 2– O 6– Si 2 is the highest in Brønsted acid strength. Besides, the acid strength weakens with the decrease of Si / Al .

Use of pyridine as a probe for the determination, by IR spectroscopy, of the Brønsted acid strength of MIHNaY zeolites

1996 ◽  
Vol 92 (7) ◽  
pp. 1263-1266 ◽  
Author(s):  
Jean-Claude Lavalley ◽  
Rodolphe Anquetil ◽  
Jolanta Czyzniewska ◽  
Maria Ziolek
Keyword(s):  
Ir Spectroscopy ◽  
Acid Strength ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid

scholarly journals Probing Brønsted Acidity of Protonic Zeolites with Variable-Temperature Infrared Spectroscopy

2018 ◽  
Vol 63 (6) ◽  
pp. 538 ◽  
Author(s):  
C. O. Areán
Keyword(s):  
Ir Spectroscopy ◽  
Variable Temperature ◽  
Bathochromic Shift ◽  
Industrial Applications ◽  
Acid Strength ◽  
Hydroxyl Groups ◽  
Weak Base ◽  
Brønsted Acidity ◽  
Brönsted Acidity ◽  
Wide Range

Most industrial applications of zeolites as solid-acid catalysts rely on their high Brønsted acidity, which affects both catalytic activity and selectivity, and hence the convenience to find an accurate experimental technique for measuring the acid strength. The enthalpy change, ΔH0, involved in the hydrogen bonding interaction between a weak base (such as carbon monoxide) and the Brønsted acid [Si(OH)Al] hydroxyl groups should correlate directly with the zeolite acid strength. However, on account of simplicity, the bathochromic shift of the O–H stretching frequency, Δv(OH), is usually measured by IR spectroscopy at a (fixed) low temperature in-stead of ΔH0 and correlated with the acid strength for ranking the zeolite acidity. Herein, the use of variable-temperature IR spectroscopy to determine simultaneously ΔH0 and Δv(OH) is demonstrated, followed by a review of recent experimental results showing that the practice of ranking the acid strength by the corresponding O–H frequency shift probed by a weak base could be misleading; and that can be so much the case of zeolites showing a wide range of structure types.

Tuning Brønsted Acid Strength by Altering Site Proximity in CHA Framework Zeolites

ACS Catalysis ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 7842-7860 ◽  
Author(s):  
Steven Nystrom ◽  
Alexander Hoffman ◽  
David Hibbitts
Keyword(s):  
Acid Strength ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid
Sign in / Sign up

Export Citation Format

Share Document