Periodic density functional investigation of Lewis acid sites in zeolites: relative strength order as revealed from NH3 adsorption

2005 ◽  
Vol 246 (1-3) ◽  
pp. 96-101 ◽  
Author(s):  
Mohamed Elanany ◽  
Michihisa Koyama ◽  
Momoji Kubo ◽  
Ewa Broclawik ◽  
Akira Miyamoto
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Sites ◽  
Relative Strength ◽  
Lewis Acid Sites ◽  
Nh3 Adsorption ◽  
Functional Investigation

NH3Adsorption on the Brönsted and Lewis Acid Sites of V2O5(010):  A Periodic Density Functional Study

1999 ◽  
Vol 103 (22) ◽  
pp. 4701-4706 ◽  
Author(s):  
Xilin Yin ◽  
Huanmei Han ◽  
Isao Gunji ◽  
Akira Endou ◽  
S. Salai Cheettu Ammal ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Sites ◽  
Functional Study ◽  
Lewis Acid Sites ◽  
Density Functional Study ◽  
Brønsted And Lewis Acid

Distribution of Al and adsorption of NH3 and pyridine in ZSM-12: a computational study

2013 ◽  
Vol 91 (10) ◽  
pp. 925-934 ◽  
Author(s):  
Gang Feng ◽  
Ying-Ying Lian ◽  
Deqin Yang ◽  
Jianwen Liu ◽  
Dejin Kong
Keyword(s):  
Density Functional Theory ◽  
Lewis Acid ◽  
Density Functional ◽  
Computational Study ◽  
Energy Difference ◽  
Acid Sites ◽  
Main Channel ◽  
Lewis Acid Sites ◽  
Small Energy ◽  
Functional Theory

The distribution of Al and the adsorption of NH3 and pyridine in both Na-form and H-form ZSM-12 were investigated using dispersion-corrected density functional theory. It was found that the energy differences for Al atoms in the different T sites of ZSM-12 (both H form and Na form) were less than 0.3 eV, which indicates that the Al atoms could distribute in all kinds of T sites in ZSM-12. In addition, the small energy difference indicates that both H and Na atoms could stay in either the small cage or the main channel of ZSM-12. The adsorption of NH3 and pyridine on NaZSM-12 is weak, while the adsorption of NH3 and pyridine on HZSM-12 is strong, as they could form NH4+ and NC5H6+ species in the presence of protons. Both NH3 and pyridine could adsorb on the Lewis Al3+ sites in HZSM-12, while the adsorption of NH3 and pyridine on the Lewis acid sites are less stable than on the Brønsted acid sites of ZSM-12.

scholarly journals Atomically dispersed Lewis acid sites boost 2-electron oxygen reduction activity of carbon-based catalysts

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Qihao Yang ◽  
Wenwen Xu ◽  
Shun Gong ◽  
Guokui Zheng ◽  
Ziqi Tian ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Acid Sites ◽  
Lewis Acidity ◽  
Structure Property ◽  
Lewis Acid Sites ◽  
Hydrogen Electrode ◽  
Voltage Range ◽  
Production Of Hydrogen

Abstract Elucidating the structure-property relationship is crucial for the design of advanced electrocatalysts towards the production of hydrogen peroxide (H2O2). In this work, we theoretically and experimentally discovered that atomically dispersed Lewis acid sites (octahedral M–O species, M = aluminum (Al), gallium (Ga)) regulate the electronic structure of adjacent carbon catalyst sites. Density functional theory calculation predicts that the octahedral M–O with strong Lewis acidity regulates the electronic distribution of the adjacent carbon site and thus optimizes the adsorption and desorption strength of reaction intermediate (*OOH). Experimentally, the optimal catalyst (oxygen-rich carbon with atomically dispersed Al, denoted as O-C(Al)) with the strongest Lewis acidity exhibited excellent onset potential (0.822 and 0.526 V versus reversible hydrogen electrode at 0.1 mA cm−2 H2O2 current in alkaline and neutral media, respectively) and high H2O2 selectivity over a wide voltage range. This study provides a highly efficient and low-cost electrocatalyst for electrochemical H2O2 production.

scholarly journals Characterization of Lewis acid sites on the (100) surface of β-AlF3: Ab initio calculations of NH3 adsorption

2008 ◽  
Vol 128 (22) ◽  
pp. 224703 ◽  
Author(s):  
C. L. Bailey ◽  
A. Wander ◽  
S. Mukhopadhyay ◽  
B. G. Searle ◽  
N. M. Harrison
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Lewis Acid ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Nh3 Adsorption

scholarly journals SYNTHESIS AND PHYSICOCHEMICAL CHARACTERISTICS OF MESOPOROUS ALUMINOSILICATES

2020 ◽  
Vol 6 (444) ◽  
pp. 22-29
Author(s):  
К.M. Umbetkaliyeva ◽  
◽  
G.K. Vassilina ◽  
А.К. Abdrassilova ◽  
А.R. Khaiyrgeldinova ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Nitrogen Adsorption ◽  
Analysis Data ◽  
Physicochemical Characteristics ◽  
Acid Sites ◽  
Relative Strength ◽  
Mesoporous Aluminosilicates ◽  
Lewis Acid Sites ◽  
Secondary Aluminum ◽  
Synthesized Materials

In the article, the synthesis of mesoporous aluminosilicates was carried out according to the developed methods, in which tetraethylorthosilicate Si(OC2H5)4 was used as a source of silicon, secondary aluminum butoxide (sec-BuO)3Al and aluminum triisopropoxide Al(i-OPr)3 were used as aluminum's sources. The synthesis of mesostructured aluminosilicate is based on the method of copolycondensation of silicon and aluminum sources in the presence of alcohol. Hexadecylamine (HDA, C16H33NH2) was used as a template for the formation of a porous structure. The physicochemical characteristics of the synthesized structured mesoporous aluminosilicates have been studied. It was found that the synthesized materials MAS-1 and MAS-2 possess high specific surface area from 511 to 1170.0 m2/g. The presence of a mesoporous and ordered structure in the synthesized aluminosilicates is confirmed by the data of low-temperature nitrogen adsorption/desorption, X-ray diffraction and FT-IR. To determine the relative strength of Brønsted and Lewis acid sites on the surface of mesoporous aluminosilicates, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of adsorbed pyridine samples was carried out. DRIFT analysis data demonstrated a majority of Lewis acid sites on the surface of the synthesized materials. We are currently studying the possibility of applying these materials as acidic components of bifunctional catalysts for petrochemical N E W S OF THE NATIONAL ACADEMY OF SCIENCES OF THE REPUBLIC OF KAZAKHSTAN SERIES CHEMISTRY AND TECHNOLOGY ISSN 2224-5286 https://doi.org/10.32014/2020.2518-1491.94 Volume 6, Number 444 (2020), 22 – 29 UDC 665.64.097.3 MRNTI 61.51.17, 61.51.19 К.M. Umbetkaliyeva1,2, G.K. Vassilina1,2, А.К. Abdrassilova1 , А.R. Khaiyrgeldinova2, Т.К. Vassilina2,3, Zh.Y. Zakirov1, М.Kh. Taliyeva2 , А.К. Kaldybayeva2 1al-Farabi Kazakh National University, Almaty, Kazakhstan; 2SRIfor New Chemical Technologies and Materials, Almaty, Kazakhstan; 3Кazakh National Agrarian University, Almaty, Kazakhstan. E-mail: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected] SYNTHESIS AND PHYSICOCHEMICAL CHARACTERISTICS OF MESOPOROUS ALUMINOSILICATES Abstract. In the article, the synthesis of mesoporous aluminosilicates was carried out according to the developed methods, in which tetraethylorthosilicate Si(OC2H5)4 was used as a source of silicon, secondary aluminum butoxide (sec-BuO)3Al and aluminum triisopropoxide Al(i-OPr)3 were used as aluminum's sources. The synthesis of mesostructured aluminosilicate is based on the method of copolycondensation of silicon and aluminum sources in the presence of alcohol. Hexadecylamine (HDA, C16H33NH2) was used as a template for the formation of a porous structure. The physicochemical characteristics of the synthesized structured mesoporous aluminosilicates have been studied. It was found that the synthesized materials MAS-1 and MAS-2 possess high specific surface area from 511 to 1170.0 m2/g. The presence of a mesoporous and ordered structure in the synthesized aluminosilicates is confirmed by the data of low-temperature nitrogen adsorption/desorption, X-ray diffraction and FT-IR. To determine the relative strength of Brønsted and Lewis acid sites on the surface of mesoporous aluminosilicates, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of adsorbed pyridine samples was carried out. DRIFT analysis data demonstrated a majority of Lewis acid sites on the surface of the synthesized materials. We are currently studying the possibility of applying these materials as acidic components of bifunctional catalysts for petrochemical processes.

scholarly journals Detecting Lewis acid sites in metal-organic frameworks by density functional theory

2022 ◽  
Vol 517 ◽  
pp. 112042
Author(s):  
Arputham Shophia Lawrence ◽  
Balasubramanian Sivakumar ◽  
Amarajothi Dhakshinamoorthy
Keyword(s):  
Density Functional Theory ◽  
Lewis Acid ◽  
Density Functional ◽  
Metal Organic Frameworks ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Functional Theory ◽  
Metal Organic
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