FTIR study of weak hydrogen bonding of Broensted hydroxyls in zeolites and aluminophosphates

Макарова, М. А.; Ojo, Adeola F.; Karim, Khalid; Hunger, Michael; Dwyer, John

doi:10.1021/j100065a013

Cited by 155 publications

(155 citation statements)

References 0 publications

Supporting

Mentioning

131

Contrasting

Unclassified

Order By: Relevance

“…1600 nm, as a consequence of the decrease of the surface potential to −29 mV (see below) resulting from the presence of electrolytes in the buffer. 45 Conversely, the contact angle remained almost unchanged (88.47 ± 0.23°), as confirmed by the t test carried out at a 95% confidence level on the PBS and water measured contact angle values.…”

Section: Agglomeration Vs Dispersion Of Siomentioning

confidence: 54%

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO₂ Nanoparticles

et al. 2015

View full text Add to dashboard Cite

The adsorption of bovine serum albumin (BSA) on two types of silica nanoparticles (NPs), one pyrolytic (P−SiO 2 ; namely AOX50 by Evonik) and the other colloidal (lab-made by using inverse micelles microemulsion, M−SiO 2 ), is studied. Both materials are characterized in terms of size of primary particles (by transmission electron microscopy), amounts (by thermogravimetry) and distribution of silanols (IR spectroscopy in controlled atmosphere, augmented by H/D isotopic exchange and reaction with VOCl 3 , to distinguish silanols actually located at the surface of nanoparticles), water contact angle, ζ−potential and dispersion state in water, PBS buffer and BSA solutions in PBS (by dynamic light scattering, DLS). Proteins are found to act as dispersing agent toward the large aggregates formed by both types of NPs in PBS buffer, although monodispersion was not attained in the conditions investigated. The problem of the determination of the silica surface actually available in NPs agglomerates for protein adsorption is addressed, and a model based on the external area of the agglomerates determined by DLS is proposed, supported by the trend of ζ−potential in dependence on the amount of adsorbed BSA and by the UV circular dichroism spectra of adsorbed proteins. The spectra reveal the occurrence of protein-protein interactions for BSA on P−SiO 2 , where multilayers of irreversibly adsorbed BSA molecules (i.e. a so called protein hard corona) are proposed to be formed. Conversely, the model indicates the formation of a sub-monolayer protein hard corona on M−SiO 2 . The difference in protein coverage appears to be related to differences in the distribution of surface silanols, more than to differences in ζ−potential.

show abstract

Section: Agglomeration Vs Dispersion Of Siomentioning

confidence: 54%

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO₂ Nanoparticles

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Initially, CO was used as probe molecules owing to its weak basicity which allows for discrimination of acid sites with different strength, in fact the adsorption of CO at 80 K produces a shift of the bands of the hydroxyls (ΔνOH) forming OH···CO hydrogenbonded adducts with the acid sites, the value of the shift has been used to estimate the acidity. [40][41][42] In Fig. 6 the FTIR spectra of adsorbed CO at 80 K on 80P and 80 H (Fig.6A) and 30P and 30H (Fig.6B) catalysts are reported.…”

Section: Resultsmentioning

confidence: 99%

Creating Accessible Active Sites in Hierarchical MFI Zeolites for Low‐Temperature Acid Catalysis

et al. 2016

View full text Add to dashboard Cite

A versatile desilication design strategy for the creation of hierarchical H-ZSM-5 catalysts with different Si/Al ratio has been demonstrated. The nature, strength and the accessibility of the acid sites after the alkaline treatment was elucidated by employing a range of physico-chemical characterization tools; notably probebased FTIR spectroscopy along with SS MAS-NMR. In addition, structural and textural properties of the hierarchical zeolites were also explored and compared to their corresponding microporous analogues. CO was used to probe the acidic properties of the hierarchical zeolites with the concomitant deployment of a bulky molecular probe, 2,4,6-trimethylpyridine (collidine), which is too large to access the micropores, to specifically investigate the enhanced accessibility of the active sites. The hierarchical zeolites were evaluated in the industrially relevant, acid-catalyzed Beckmann rearrangement of cyclohexanone oxime to -caprolactam, the precursor for Nylon-6, in liquid phase and at low-temperatures. The catalytic findings with the hierarchical catalysts reveal a significant enhancement in the production of -caprolactam, compared with the parent microporous H-ZSM-5 zeolite, thereby highlighting the merits of our design approach in facilitating enhanced diffusion and masstransfer.

show abstract

“…The broadening and increase in intensity upon formation of the complex is common to H-bonded complexes and has also been observed in zeolites. 31 The peak at 992 cm -1 corresponds to C-H wagging modes. It is important to emphasize here, as evident from spectra 5b and 5c, that the Si-OD group does not form any complex with C 2 H 4 because of its low acidic character.…”

mentioning

confidence: 99%

Exploring Zeolite Chemistry with the Tools of Surface Science: Challenges, Opportunities, and Limitations

Boscoboinik

Shaikhutdinov

2014

Catal Lett

View full text Add to dashboard Cite

The complexity of catalysts that the surface science community has been able to address has increased substantially in a systematic manner, starting with metal and oxide single crystal surfaces and evolving to an atomistic description of clusters and nanoparticles on well-defined, planar supports. The next step in adding complexity is now to address surfaces of porous oxide materials, in particular of zeolites, which are the most extensively used catalysts in the industry. The recently reported successful fabrication of well-ordered thin films, consisting of planar arrangement of aluminosilicate polygonal prisms on a metal substrate counting with highly acidic bridging hydroxyl groups on the surface, represents the limiting case of infinitely large pore and cages in zeolites. This model system allows one to study reactions catalyzed by zeolites using the toolkit of surface science. In this Perspective, we describe the zeolitic model system, with its virtues and limitations, as well as the challenges, opportunities and expectations for the future in modelling porous catalysts by a surface science approach.

show abstract

FTIR study of weak hydrogen bonding of Broensted hydroxyls in zeolites and aluminophosphates

Cited by 155 publications

References 0 publications

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO₂ Nanoparticles

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO₂ Nanoparticles

Creating Accessible Active Sites in Hierarchical MFI Zeolites for Low‐Temperature Acid Catalysis

Exploring Zeolite Chemistry with the Tools of Surface Science: Challenges, Opportunities, and Limitations

Contact Info

Product

Resources

About

FTIR study of weak hydrogen bonding of Broensted hydroxyls in zeolites and aluminophosphates

Cited by 155 publications

References 0 publications

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO2 Nanoparticles

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO2 Nanoparticles

Creating Accessible Active Sites in Hierarchical MFI Zeolites for Low‐Temperature Acid Catalysis

Exploring Zeolite Chemistry with the Tools of Surface Science: Challenges, Opportunities, and Limitations

Contact Info

Product

Resources

About

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO₂ Nanoparticles

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO₂ Nanoparticles