A Pulsed Electron Nuclear Double Resonance Study of the Lewis Acid Site−Nitric Oxide Complex in Zeolite H-ZSM-5

1998 ◽  
Vol 120 (19) ◽  
pp. 4879-4880 ◽  
Author(s):  
Andreas Pöppl ◽  
Thomas Rudolf ◽  
Dieter Michel
Keyword(s):  
Nitric Oxide ◽  
Lewis Acid ◽  
Acid Site ◽  
Double Resonance ◽  
Lewis Acid Site ◽  
Electron Nuclear Double Resonance

Lewis Acid Site-Promoted Single-Atomic Cu Catalyzes Electrochemical CO2 Methanation

Nano Letters ◽  
2021 ◽  
Author(s):  
Shenghua Chen ◽  
Bingqing Wang ◽  
Jiexin Zhu ◽  
Liqiang Wang ◽  
Honghui Ou ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Acid Site ◽  
Lewis Acid Site ◽  
Co2 Methanation

Solution Tetrahydrobiopterin Radical vs. the Enzyme-Bound Radical: A Paramagnetic Reconciliation

2021 ◽  
Vol 16 ◽  
Author(s):  
Yaser Nejaty Jahromy
Keyword(s):  
Nitric Oxide ◽  
Density Functional ◽  
Double Resonance ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Cation Radical ◽  
Spectral Simulation ◽  
Electron Nuclear Double Resonance ◽  
Paramagnetic Resonance ◽  
Isotropic Hyperfine Coupling ◽  
The 1960S

Background: Nitric oxide synthase (NOS) catalyzes the formation of nitric oxide (NO) and citrulline from L-arginine, dioxygen (O2), and nicotinamide adenine dinucleotide phosphate (NADPH) in a two-step reaction, with the enzyme-bound intermediate Nω-hydroxy-L-arginine (NHA). Previous electron paramagnetic resonance (EPR) studies of NOS reaction have shown that (6R, 1'R, 2'S)-6-(l',2'-dihydroxypropyl)-5,6,7,8-tetrahydropterin (H4B) acts as a single electron donor in both steps of the reaction, resulting in the transient generation of a tetrahydropterin cation radical (H4B•+). Results: H4B•+ can also be chemically generated in strongly acidic solutions. EPR studies of chemically generated H4B•+ and similar pterin radicals date back to the 1960s. However, the reported paramagnetic parameters of H4B•+ in NOS do not seem to match the corresponding reported parameters for either H4B•+ or other pterin centered radicals chemically generated in solution. In particular, the rather isotropic hyperfine coupling of ca. 45 MHz for 1H6 of H4B•+ in NOS is at least 15 MHz larger than that of H4B•+ or any other previously studies pterin solution radical. In the work reported here, a combination of 9.5 - 9.8 GHz contentious wave (cw-) EPR, 34GHz 1H electron nuclear double resonance (ENDOR), spectral simulation and Density Functional Theory (DFT) calculations were used to investigate this seeming discrepancy. Conclusion: We demonstrated that the differences in the paramagnetic parameters of the chemically generated H4B radicals in solutions and those of the H4B radicals in NOS are consistent with the presence of two different conformers of the same cation radical in the two media.

Bimetallic Metal-Organic Frameworks: Probing the Lewis Acid Site for CO2Conversion

Small ◽  
2016 ◽  
Vol 12 (17) ◽  
pp. 2334-2343 ◽  
Author(s):  
Ruyi Zou ◽  
Pei-Zhou Li ◽  
Yong-Fei Zeng ◽  
Jia Liu ◽  
Ruo Zhao ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Acid Site ◽  
Metal Organic Frameworks ◽  
Lewis Acid Site ◽  
Metal Organic

scholarly journals Lewis Acid Site and Hydrogen-Bond-Mediated Polarization Synergy in the Catalysis of Diels–Alder Cycloaddition by Band-Gap Transition-Metal Oxides

ACS Catalysis ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 701-715 ◽  
Author(s):  
Taha Salavati-fard ◽  
Efterpi S. Vasiliadou ◽  
Glen R. Jenness ◽  
Raul F. Lobo ◽  
Stavros Caratzoulas ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Transition Metal ◽  
Metal Oxides ◽  
Band Gap ◽  
Lewis Acid ◽  
Transition Metal Oxides ◽  
Acid Site ◽  
Lewis Acid Site ◽  
Diels Alder

Propane Dehydrogenation Catalyzed by Single Lewis Acid Site in Sn-Beta Zeolite

2021 ◽  
Author(s):  
Yuanyuan Yue ◽  
Jing Fu ◽  
Chuanming Wang ◽  
Pei Yuan ◽  
Xiaojun Bao ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Acid Site ◽  
Lewis Acid Site ◽  
Propane Dehydrogenation ◽  
Beta Zeolite

scholarly journals Sintesis Dan Karakterisasi H-Aluminosilikat Sebagai Katalis Sintesis Biogasoline Dari Asam Oleat

2019 ◽  
Vol 4 (2) ◽  
pp. 100
Author(s):  
Deasi Adhiani Farida ◽  
Abdulloh Abdulloh ◽  
Ahmadi Jaya Permana
Keyword(s):  
Oleic Acid ◽  
Hydrothermal Method ◽  
Lewis Acid ◽  
Acid Site ◽  
Lewis Acid Site ◽  
Bronsted Acid ◽  
Bronsted Acid Site ◽  
Brønsted Acid Site ◽  
Brönsted Acid ◽  
Cracking Reaction

ABSTRACT          Aluminosilicate can be used for cracking reaction. In this study, catalyst of H-aluminosilicate has been synthesized by hydrothermal method with ratio molar Si/Al is 20. The characterizations has been performed by XRD, FTIR and acidity test. Characterization by XRD showed that catalyst of H-aluminosilicate have structure amorphous, while FTIR showed Si-O-Al bond at 457 cm-1. The acidity test showed that catalyst of H-aluminosilicate have Brønsted acid site 0.0272 mmol/g and Lewis acid site 0.0005 mmol/g. Oleic acid was cracking at 340 oC for 3 and 5 hours. The product has been analyzed by GC-MS not showed compound forming biogasoline.Keywords: H-aluminosilicate, biogasoline, oleic acid ABSTRAK          Aluminosilikat dapat digunakan sebagai katalis dalam reaksi prengkahan. Pada penelitian ini telah dilakukan sintesis katalis H-aluminosilikat melalui metode hidrotermal dengan rasio Si/Al sebesar 20. Karakterisasi yang telah dilakukan meliputi uji XRD, FTIR, dan keasaman.Hasil XRD menunjukkan katalis H-aluminosilikat berbentuk amorf, sedangkan pada FTIR menunjukkan ikatan Si-O-Al pada bilangan gelombang 457 cm-1. Uji situs asam menunjukkan katalis H-aluminosilikat memiliki jumlah asam Brønsted sebesar 0.0272 mmol/g dan jumlah sisi asam Lewis sebesar 0.0005 mmol/g. Proses perengkahan asam oleat telah dilakukan pada suhu 340oC selama 3 jam dan 5 jam. Produk cracking yang diuji dengan GC-MS tidak menunjukkan pembentukan senyawa biogasoline.Kata kunci: H-aluminosilikat, biogasoline, asam oleat

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