scholarly journals Solid Acid-Catalyzed Cellulose Hydrolysis Monitored by In Situ ATR-IR Spectroscopy

ChemSusChem ◽  
2012 ◽  
Vol 5 (2) ◽  
pp. 430-437 ◽  
Author(s):  
Joseph Zakzeski ◽  
Ruud J. H. Grisel ◽  
Arjan T. Smit ◽  
Bert M. Weckhuysen
Keyword(s):  
Ir Spectroscopy ◽  
Solid Acid ◽  
Cellulose Hydrolysis ◽  
Acid Catalyzed

The Initial Stages of Solid Acid-Catalyzed Reactions of Adsorbed Propane. A Mechanistic Study by in Situ MAS NMR

2004 ◽  
Vol 126 (2) ◽  
pp. 599-606 ◽  
Author(s):  
Mohamed Haouas ◽  
Stéphane Walspurger ◽  
Francis Taulelle ◽  
Jean Sommer
Keyword(s):  
Solid Acid ◽  
Mas Nmr ◽  
Mechanistic Study ◽  
Acid Catalyzed ◽  
Catalyzed Reactions

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

The Nature of Chemisorbed CO2 in Zeolite A

2019 ◽  
Author(s):  
Przemyslaw Rzepka ◽  
Zoltán Bacsik ◽  
Andrew J. Pell ◽  
Niklas Hedin ◽  
Aleksander Jaworski
Keyword(s):  
Solid State ◽  
Ir Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Surface Coverage ◽  
Gas Mixtures ◽  
Mas Nmr ◽  
Significant Fraction ◽  
Zeolite A

Formation of CO<sub>3</sub><sup>2-</sup> and HCO<sub>3</sub><sup>-</sup> species without participation of the framework oxygen atoms upon chemisorption of CO<sub>2</sub> in zeolite |Na<sub>12</sub>|-A is revealed. The transfer of O and H atoms is very likely to have proceeded via the involvement of residual H<sub>2</sub>O or acid groups. A combined study by solid-state <sup>13</sup>C MAS NMR, quantum chemical calculations, and <i>in situ</i> IR spectroscopy showed that the chemisorption mainly occurred by the formation of HCO<sub>3</sub><sup>-</sup>. However, at a low surface coverage of physisorbed and acidic CO<sub>2</sub>, a significant fraction of the HCO<sub>3</sub><sup>-</sup> was deprotonated and transformed into CO<sub>3</sub><sup>2-</sup>. We expect that similar chemisorption of CO<sub>2</sub> would occur for low-silica zeolites and other basic silicates of interest for the capture of CO<sub>2</sub> from gas mixtures.

Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

1980 ◽  
Vol 45 (8) ◽  
pp. 2219-2223 ◽  
Author(s):  
Marie Jakoubková ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Electron Density ◽  
Phosphorus Atom ◽  
Proton Acceptor ◽  
Trimethylsilyl Group ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

scholarly journals Hierarchical HZSM-5 for Catalytic Cracking of Oleic Acid to Biofuels

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 747
Author(s):  
Mahashanon Arumugam ◽  
Chee Keong Goh ◽  
Zulkarnain Zainal ◽  
Sugeng Triwahyono ◽  
Adam F. Lee ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Solid Acid ◽  
High Surface ◽  
High Surface Area ◽  
Acid Catalyst ◽  
Hierarchical Network ◽  
Waste Oil ◽  
Acid Catalyzed ◽  
Zeolite Seeds ◽  
20 Nm

Solid acid catalyzed cracking of waste oil-derived fatty acids is an attractive route to hydrocarbon fuels. HZSM-5 is an effective acid catalyst for fatty acid cracking; however, its microporous nature is susceptible to rapid deactivation by coking. We report the synthesis and application of hierarchical HZSM-5 (h-HZSM-5) in which silanization of pre-crystallized zeolite seeds is employed to introduce mesoporosity during the aggregation of growing crystallites. The resulting h-HZSM-5 comprises a disordered array of fused 10–20 nm crystallites and mesopores with a mean diameter of 13 nm, which maintain the high surface area and acidity of a conventional HZSM-5. Mesopores increase the yield of diesel range hydrocarbons obtained from oleic acid deoxygenation from ~20% to 65%, attributed to improved acid site accessibility within the hierarchical network.

In Situ IR Spectroscopy for Following the Copolymerization of CO2and Epoxides

2014 ◽  
Vol 86 (9) ◽  
pp. 1627-1628
Author(s):  
K. Böhm ◽  
W. Leitner ◽  
T. E. Müller
Keyword(s):  
Ir Spectroscopy ◽  
In Situ Ir ◽  
In Situ Ir Spectroscopy

Rational Design of Solid-Acid Catalysts for Cellulose Hydrolysis Using Colloidal Theory

2021 ◽  
Author(s):  
Ziyang Zhang ◽  
Geoffrey A Tompsett ◽  
Christopher Lambert ◽  
Sergio Granados-Focil ◽  
Michael T. Timko
Keyword(s):  
Rational Design ◽  
Solid Acid ◽  
Molecular Level ◽  
Cellulose Hydrolysis ◽  
Solid Acid Catalysts ◽  
Acid Catalysts

Solid-acid catalysts functionalized with catalytic groups have attracted intense interests for hydrolyzing cellulose into fermentable compounds. However, the solid-acid catalysts design has been guided by molecular level of interactions and...

scholarly journals In Situ IR Spectroscopy of Mesoporous Silica Films for Monitoring Adsorption Processes and Trace Analysis

2018 ◽  
Vol 1 (12) ◽  
pp. 7083-7091 ◽  
Author(s):  
Bettina Baumgartner ◽  
Jakob Hayden ◽  
Andreas Schwaighofer ◽  
Bernhard Lendl
Keyword(s):  
Ir Spectroscopy ◽  
Mesoporous Silica ◽  
Trace Analysis ◽  
Silica Films ◽  
In Situ Ir ◽  
Adsorption Processes ◽  
In Situ Ir Spectroscopy
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