Interaction of ammonia with Broensted acid sites in different cages of zeolite Y as studied by proton MAS NMR

1993 ◽  
Vol 97 (40) ◽  
pp. 10394-10402 ◽  
Author(s):  
W. P. J. H. Jacobs ◽  
J. W. de Haan ◽  
L. J. M. van de Ven ◽  
R. A. van Santen
Keyword(s):  
Zeolite Y ◽  
Acid Sites ◽  
Mas Nmr

THE USE OF THE COMBINATION OF FTIR, PYRIDINE ADSORPTION, 27Al AND 29Si MAS NMR TO DETERMINE THE BRÖNSTED AND LEWIS ACIDIC SITES

2016 ◽  
Vol 78 (6) ◽  
Author(s):  
Djoko Hartanto ◽  
Lai Sin Yuan ◽  
Sestriana Mutia Sari ◽  
Djarot Sugiarso ◽  
Irmina Kris Murwarni ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Aluminum Atom ◽  
Xrd Analysis ◽  
Acid Sites ◽  
Mas Nmr ◽  
Molar Ratio ◽  
Pyridine Adsorption ◽  
Lewis Acid Sites ◽  
27Al Mas Nmr ◽  
Pre Treatment

Lewis and Brönsted acidity were studied on ZSM-5 with combination of pyridine adsorption and FTIR vibration, ZSM-5 synthesized using kaolin Bangka Indonesia with an increase in the molar ratio of Si/Al 30-60 without pre-treatment and without organic templates and with seeds silicalite. Interestingly, the intensity of the infrared showed an increase of band vibration pyridine as absorbed Brönsted and Lewis acid sites in a molar ratio increase of Si/Al in ZSM-5, indicating an increase in the number of silanol (Brönsted acid) and deformed silica (Lewis acid) because the amount of Aluminum in ZSM-5 decrease with increase Si/Al but amount acidity increase. 29Si and 27Al MAS NMR analysis was supported by the results of infrared to indicate that all of the aluminum atom is coordinated with their neighbors are the same in ordering the ZSM-5 framework and 27Al MAS NMR showed a sharp peak of all the variations of Si/Al except the Si/Al 30 shows a low peak area. XRD analysis supported that the ZSM-5 structure formed is pure and crystal and a decrease in crystallinity proven for more than Si/Al 50, that defects silica occurs in ZSM-5, this corresponds to the growing number of Lewis acid sites caused by defects silica described the infrared results.

1H mas NMR and IR studies of the acidic properties of realuminated zeolite Y

1989 ◽  
Vol 3 (3) ◽  
pp. 263-272 ◽  
Author(s):  
Jacek Klinowski ◽  
Halimaton Hamdan ◽  
Avelino Corma ◽  
Vincente Forn�s ◽  
Michael Hunger ◽  
...  
Keyword(s):  
Zeolite Y ◽  
Mas Nmr ◽  
Acidic Properties ◽  
1H Mas Nmr ◽  
Ir Studies

scholarly journals Effect of Additives on the Activity of Nickel–Tungsten Sulfide Hydroconversion Catalysts Prepared In Situ from Oil-Soluble Precursors

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 644 ◽  
Author(s):  
Mariia Kniazeva ◽  
Anton Maximov
Keyword(s):  
Zeolite Y ◽  
Acid Sites ◽  
System Component ◽  
Gas Oil ◽  
Tungsten Sulfide ◽  
Silica Alumina ◽  
Acidic Component ◽  
Amorphous Aluminosilicate ◽  
Nickel Tungsten

The nickel–tungsten sulfide catalysts for the hydroconversion of hydrocarbons were prepared from oil-soluble nickel and tungsten precursor compounds in situ with the use of silica, alumina, titania, zeolite Y, and amorphous aluminosilicate as additives in a vacuum gas oil medium. It was found that the catalytic activity in hydrocracking depends on the concentration of acid sites in the resulting catalyst. With the use of oxide additives, the dispersion and the promoter ratio of the in situ formed sulfide particles increased in the order SiO2–Al2O3–TiO2. It was noted that the promoter ratio of sulfide particles obtained with the use of aluminosilicate additives depended on their porous structure peculiarities. The use of titanium dioxide as a catalytic system component made it possible to reach high activity in hydrocracking, hydrodearomatization, and hydrodesulfurization, which was comparable to that of a system based on zeolite Y, a highly acidic component.

scholarly journals Effect of aluminum and sodium on the sorption of water and methanol in microporous MFI-type zeolites and mesoporous SBA-15 materials

Adsorption ◽  
2020 ◽  
Author(s):  
Zheng Li ◽  
Carolin Rieg ◽  
Ann-Katrin Beurer ◽  
Michael Benz ◽  
Johannes Bender ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Acid Sites ◽  
Mas Nmr ◽  
Nmr Studies ◽  
Oh Groups ◽  
Adsorption Sites ◽  
Low Field ◽  
Strong Adsorption ◽  
Nmr Signals

Abstract The interaction and nature of surface sites for water and methanol sorption on MFI-type zeolites and mesoporous SBA-15 were investigated by solid-state NMR spectroscopy and correlated with the desorption enthalpies determined via TGA/DSC. For siliceous Silicalite-1, 29Si CPMAS NMR studies support stronger methanol than water interactions with SiOH groups of Q3-type. On siliceous SBA-15, SiOH groups of Q2-type are accompanied by an enhanced hydrophilicity. In aluminum-containing Na-ZSM-5, Na+ cations are strong adsorption sites for water and methanol as evidenced by 23Na MAS NMR in agreement with high desorption enthalpies of ΔH = 66–74 kJ/mol. Solid-state NMR of aluminum-containing Na-[Al]SBA-15, in contrast, has shown negligible water and methanol interactions with sodium and aluminum. Desorption enthalpies of ΔH = 44–60 kJ/mol hint at adsorption sites consisting of SiOH groups influenced by distant framework aluminum. On H-ZSM-5, Brønsted acidic OH groups are strong adsorption sites as indicated by partial protonation of water and methanol causing low-field shifts of their 1H MAS NMR signals and enhanced desorption enthalpies. Due to the small number of Brønsted acid sites in aluminum-containing H-[Al]SBA-15, water and methanol adsorption on this material is suggested to mainly occur at SiOH groups with distant framework aluminum species, as in the case of Na-[Al]SBA-15.

Brønsted and Lewis Acid Sites in Dealuminated ZSM-12 and β Zeolites Characterized by NH3-STPD, FT-IR, and MAS NMR Spectroscopy

2000 ◽  
Vol 104 (17) ◽  
pp. 4122-4129 ◽  
Author(s):  
Wenmin Zhang ◽  
Panagiotis G. Smirniotis ◽  
M. Gangoda ◽  
Rathindra N. Bose
Keyword(s):  
Nmr Spectroscopy ◽  
Lewis Acid ◽  
Acid Sites ◽  
Mas Nmr ◽  
Lewis Acid Sites ◽  
Ft Ir ◽  
Brønsted And Lewis Acid

A solid-state NMR study of acid sites in zeolite Y using ammonia and trimethylamine as probe molecules

1987 ◽  
Vol 91 (8) ◽  
pp. 2091-2095 ◽  
Author(s):  
William L. Earl ◽  
Paul O. Fritz ◽  
Atholl A. V. Gibson ◽  
Jack H. Lunsford
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Zeolite Y ◽  
Acid Sites ◽  
Probe Molecules ◽  
Nmr Study

The catalytic effect of boron substitution in MCM-41-type molecular sieves

2004 ◽  
Vol 82 (5) ◽  
pp. 631-640 ◽  
Author(s):  
V Sundaramurthy ◽  
I Eswaramoorthi ◽  
N Lingappan
Keyword(s):  
Molecular Sieves ◽  
Boron Content ◽  
Acid Sites ◽  
Mas Nmr ◽  
Catalyst Characterization ◽  
Secondary Products ◽  
Hydrogen Shift ◽  
Wide Range ◽  
Ft Ir ◽  
Mcm 41

A series of B-MCM-41 samples has been synthesized with a wide range of boron content (SiO2:B2O3 ratio from 20 to 200), using ethyl silicate ester-40 (ES-40) as the silica source and characterized by XRD, BET, FT-IR, 11B-MAS NMR, SEM, pyridine adsorption, TPDA, and chemical analysis. The interplanar d100 spacing varies from 40 to 45 Å, depending on the Si:B ratio. On calcination, a significant amount of four-coordinated boron is converted into less stable three-coordinated boron, and some boron is removed from the framework. The degree of deboronation increases with an increase of boron content of the sample. The B substitution in the MCM-41 framework results in only weak and mild acid sites. The isomerization of 1-hexene is found to be influenced by the boron content in the framework. The isomerization leads to both a hydrogen shift and skeletal rearrangement. The selectivity ratios of cis-2-hexene to trans-2-hexene and 2-hexene to 3-hexene were found to decrease with an increase of temperature and a decrease of the SiO2:B2O3 ratio of the catalysts. Skeletal isomerization starts at 250 °C, forming secondary products, and increases with an increase of temperature and an increase of boron content of the catalysts. Key words: ES-40, B-MCM-41, deboronation, catalyst characterization, XRD, BET, FT-IR, 11B-MAS NMR, SEM, 1-hexene isomerization, 2-hexene.

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