Journal ArticleDOI
An Infrared Spectroscopic Study of Acetone and Mesityl Oxide Adsorption on Acid Catalyst
A. Panov,J. J. Fripiat +1 more
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In this paper, a quasi-one-to-one relation between the number of bridging OH in a cluster Si−nAl containing only one Al and the amount of strongly hydrogen-bonded acetone was established.Abstract:
The interactions between the acetone carbonyl and the carbonyl and double bond of mesityl oxide and the Bronsted and Lewis acid sites of acid catalysts have been studied by Fourier Transform infrared (FTIR) spectroscopy. The acetone carbonyl interactions with bridging acidic OH and with bridging weakly acidic OH can be distinguished from one another semiquantitatively. This was substantiated by a quasi one-to-one relation between the number of bridging OH in a cluster Si−nAl containing only one Al and the number of strongly hydrogen-bonded acetone. The distinction between Bronsted and Lewis sites is not easy with acetone, while it is with mesityl oxide. The system acetone−mesityl oxide adsorbed an acid catalysts is rather unique, since the reagent and the reaction product of the condensation reaction are qualitatively and quantitatively detectable by FTIR spectroscopy. The quantitative determination of the coverage of the acid sites by the reagent and the reaction product was a prerequisite to the study o...read more
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Environmentally-benign catalysts for the selective catalytic reduction of NOx from diesel engines: structure–activity relationship and reaction mechanism aspects
Fudong Liu,Yunbo Yu,Hong He +2 more
TL;DR: Based on research, a comprehensive mechanism contributing to the performance of Ag/Al2O3 in HC-SCR is provided, giving a clue to the design of a catalytic system with high efficiency.
Journal ArticleDOI
Generation of a solid Brønsted acid site in a chiral framework.
Michael J. Ingleson,Jorge Perez Barrio,John Bacsa,Calum Dickinson,Hyunsoo Park,Matthew J. Rosseinsky +5 more
TL;DR: Protonation of chiral porous materials introduces a Brønsted acid centre, the structure of which is unique to the heterogeneous phase requiring pore wall confinement for stable isolation.
Journal ArticleDOI
Surface Reactions of Acetone on Al2O3, TiO2, ZrO2, and CeO2: IR Spectroscopic Assessment of Impacts of the Surface Acid−Base Properties
TL;DR: In this paper, it was found that the availability of Lewis acid sites is essential for anchoring acetone molecules to the surface, and when intimately coupled, the Lewis acid and base sites generate pair sites of particularly strong adsorption capacity toward condensation products thus formed.
Journal ArticleDOI
Adsorption and photocatalytic oxidation of acetone on TiO2: An in situ transmission FT-IR study
Mohamed El-Maazawi,Mohamed El-Maazawi,A.N. Finken,A.N. Finken,A.B. Nair,A.B. Nair,Vicki H. Grassian,Vicki H. Grassian +7 more
TL;DR: In this paper, the authors used infrared spectroscopy to study the mechanistic details of adsorption and photocatalytic oxidation of acetone on TiO2 surfaces at 298 K. Infrared spectra at low acetone coverages (θ < 0.05 ML) show absorption bands at 2973, 2931, 1702, 1448, and 1363 cm−1 which are assigned to the vibrational modes of molecularly adsorbed acetone.
Journal ArticleDOI
The effect of solvent addition on fructose dehydration to 5-hydroxymethylfurfural in biphasic system over zeolites
TL;DR: In this paper, the effect of organic solvent addition during dehydration of fructose over zeolites has been investigated as a way to enhance the 5-hydroxymethylfurfural (HMF) selectivity.
References
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Journal ArticleDOI
Lewis Acid Sites and Surface Aluminum in Aluminas and Zeolites: A High-Resolution NMR Study
Abstract: It was the main purpose of this work to study the nature of Lewis acidity in various catalysts (aluminas and zeolites) pretreated under controlled atmosphere at different temperatures. Isotopically enriched ammonia [sup 15]NH[sub 3] chemisorption was employed to probe the surface active sites and to allow for magnetization transfer to surface and close-to-surface Al nuclei. A special deconvolution procedure was applied to obtain [sup 27]Al spectral parameters for different Al sites in partially resolved spectra. The procedure accounted for the normal distribution of electric field gradient tensor components at a particular site. It is shown that there are two kinds of Lewis sites on aluminas: namely, a tetrahedral site with isotropic shift of about 58 ppm and quadrupolar coupling constant QCC [approx equal] 6 MHz and a pentagonal site with a isotropic shift of about 40 ppm and a slightly smaller QCC. In zeolites the same kinds of sites exist in the nonframework aluminum debris, and in addition, the Broensted sites are associated with framework aluminum. 32 refs., 8 figs., 5 tabs.
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Acidic properties of H-beta zeolite as probed by bases with proton affinity in the 118-204 kcal mol(-1) range: A FTIR investigation
TL;DR: In this article, the vibrational properties of 1:1 neutral adducts were studied and the effect of the proton potential on the vibration of the adduct was analyzed.
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Toward a Systematic Chemistry of Organic Reactions in Zeolites: In situ NMR Studies of Ketones
TL;DR: In this article, the reactions of acetone and cyclopentanone on a variety of zeolites with different acidities and pore sizes were investigated in detail by both in situ 13 C solid-state NMR and ex situ methods following extraction.
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A 13C NMR Study of the Condensation Chemistry of Acetone and Acetaldehyde Adsorbed at the Brønsted Acid Sites in H-ZSM-5
TL;DR: In this paper, bimolecular acid-catalyzed condensation reactions of acetone and acetaldehyde have been examined in H-ZSM-5, along with the adsorption complexes formed by the products, using 13C NMR.