نتایج جستجو برای: Brönsted acid

تعداد نتایج: 747496  

2015
Amin Osatiashtiani Adam F. Lee Marta Granollers D. Robert Brown Luca Olivi Gabriel Morales Juan A. Melero Karen Wilson

The grafting and sulfation of zirconia conformal monolayers on SBA-15 to create mesoporous catalysts of tunable solid acid/base character is reported. Conformal zirconia and sulfated zirconia (SZ) materials exhibit both Brönsted and Lewis acidity, with the Brönsted/Lewis acid ratio increasing with film thickness and sulfate content. Grafted zirconia films also exhibit amphoteric character, whos...

2017
Qing Shu Guo-qiang Tang Feng-sheng Liu Hai-yan Wei

Waste camellia seed shell was placed in fluidized bed tubular reactor and carbonized at 700°C for the preparation of a carbon material, and which was then used as the support for the synthesis of a novel solid Brönsted acid catalyst H3PW12O40/C by impregnation of it with H3PW12O40 solution. The obtained H3PW12O40/C catalyst was characterized by scanning electron microscope, X-ray diffraction, t...

2016
Miao He Jie Zhang Rui Liu Xiuliang Sun Biaohua Chen José R. B. Gomes

One of the fundamental issues in catalysis is to identify the catalytic active site. Due to its prominent pore topology and acidity, ferrierite (FER) zeolite has attracted extensive interest in various catalytic reactions such as isomerization of butenes. However knowledge on the active Brönsted acid site is still absent. In the present study, we perform extensive density functional theory calc...

Journal: :Chemical communications 2013
Paula Rubio-Marqués Antonio Leyva-Pérez Avelino Corma

Nitroderivatives are transformed to cyclohexylanilines at room temperature in good yields and selectivity via a hydrogenation-amine coupling cascade reaction using Pd nanoparticles on carbon as a catalyst and a Brönsted acid.

Journal: :Chemical communications 2014
Changlei Chen Sha Li Shaodan Xu Hui Lou Liping Xiao Jie Fan

A thermal and hydrothermal stable mesoporous ceramic acid (mCA) was synthesized by uniform coating of a WZrO(x) layer onto the internal surface of extra-large mesoporous silica (EP-FDU-12). Its ordered mesoporous structure and strong Brönsted acid sites display excellent thermal (1000 °C, air, 5 h) and hydrothermal (water steam, 300 °C, 24 h) stability.

Journal: :iranian journal of catalysis 2014
esmayeel abbaspour-gilandeh seyyedeh cobra azimi

the brønsted acidic ionic liquid ([bmim]hso4) catalyzed three-component synthesis of 2h-indazolo[2,1-b]phthalazine-trione derivatives at room temperature. the integrity of the ionic liquid remains reasonably unchanged when it is separated from the reaction mixture by water extraction, as it can be recycled several times without any loss of activity in each of the title syntheses. the products a...

Journal: :Zeitschrift fur Naturforschung. Section C, Biosciences 1976
D Petz F Schneider

The catalytic properties of peptides containing histidine, cysteine and aspartic acid in ester hydrolysis were studied. Saturation kinetics were found for the reaction of p-nitrophenyl acetate (NPA) with Z-His-Ala-Asp-Gly-Cys-NH2 and Z-His-Ala-Gly-Cly-Cys-NH2. The Brönsted equation for the hydrolysis of tert-butyloxcarbonyl-L-alanine-p-nitrophenylester (Bos-Ala-ONp) catalyzed by simple imidazol...

Journal: :The Journal of General Physiology 1936
R. Brdička

1. The rate of the saponification of iodoacetic acid in sodium hydroxide and alkaline buffer solutions yielding glycollic acid was measured by means of Heyrovský's polarographic method. 2. From the bimolecular velocity constants, increasing with the ionic strength of the solution, the Brönsted factor, F, which characterizes the primary salt effect, was calculated. 3. In the borate buffer soluti...

2012
Aurora J. Cruz-Cabeza Dolores Esquivel César Jiménez-Sanchidrián Francisco J. Romero-Salguero

Various metal-β zeolites have been synthesized under similar ion-exchange conditions. During the exchange process, the nature and acid strength of the used cations modified the composition and textural properties as well as the Brönsted and Lewis acidity of the final materials. Zeolites exchanged with divalent cations showed a clear decrease of their surface Brönsted acidity and an increase of ...

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