scholarly journals Natural clay nanotube supported Mo and W catalysts for exhaustive oxidative desulfurization of model fuels

2021 ◽  
Vol 93 (2) ◽  
pp. 231-241
Author(s):  
Argam Akopyan ◽  
Polina Polikarpova ◽  
Anna Vutolkina ◽  
Kirill Cherednichenko ◽  
Valentine Stytsenko ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Heterogeneous Catalysts ◽  
Sulfur Removal ◽  
Oxidative Desulfurization ◽  
Halloysite Nanotubes ◽  
Acid Sites ◽  
Molar Ratio

Abstract Oxidative desulfurization is a promising way to produce, under mild conditions, clean ecological fuels with ultra-low sulfur content. Herein, we present for the first time heterogeneous catalysts based on natural aluminosilicate nanotubes (halloysite) loaded with transition metal oxides for oxidative sulfur removal using hydrogen peroxide as environmentally safe oxidant. The halloysite nanotubes (HNTs) provide acid sites for C–S bond scission, while the Mo and W oxides act as hydrogen peroxide activators. The structure and acidity of both the clay support and catalysts were investigated by low-temperature nitrogen adsorption/desorption, Fourier-transform infrared spectroscopy, X-ray fluorescence analysis, and transmission electron microscopy techniques. These clay-based catalysts revealed the high activity in the oxidation of various classes of sulfur-containing compounds (sulfides, heteroatomic sulfur compounds) under mild reaction conditions. The conversion of various substrates decreases in the following trend: MeSPh > Bn2S > DBT > 4-MeDBT > BT, which deals with substrate electron density and steric hindrance. The influence of the temperature, oxidant to sulfur molar ratio, and reaction time on catalytic behavior was evaluated for Mo- and W-containing systems with various metal content. The complete oxidation of the most intractable dibenzothiophene to the corresponding sulfone was achieved at 80 °C and H2O2:S = 6:1 (molar) for 2 h both for Mo- and W-containing systems. These transition metal oxides HNTs supported catalysts are stable for 10 cycles of dibenzothiophene oxidation, which makes them promising systems for clean fuel production.

Titanium dioxide supported on MWCNTs as an eco-friendly catalyst in the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones accelerated under microwave irradiation

2014 ◽  
Vol 38 (8) ◽  
pp. 3514-3521 ◽  
Author(s):  
Javad Safari ◽  
Soheila Gandomi-Ravandi
Keyword(s):  
Titanium Dioxide ◽  
Transition Metal ◽  
Microwave Irradiation ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Heterogeneous Catalysts ◽  
Biginelli Compounds

Some transition metal oxides supported on MWCNTs were prepared as novel heterogeneous catalysts using the facile processes. These catalysts were used for the synthesis of Biginelli compounds under microwave irradiation.

Polymeric Heterogeneous Catalysts of Transition-Metal Oxides: Surface Characterization, Physicomechanical Properties, and Catalytic Activity

ChemPhysChem ◽  
2013 ◽  
Vol 14 (18) ◽  
pp. 4149-4157 ◽  
Author(s):  
Bui Dinh Nhi ◽  
Renat Maratovich Akhmadullin ◽  
Alfiya Garipovna Akhmadullina ◽  
Yakov Dmitrievich Samuilov ◽  
Svetlana Ivanova Aghajanian
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Surface Characterization ◽  
Heterogeneous Catalysts ◽  
Physicomechanical Properties

scholarly journals Oxidative Desulfurization of Diesel Fuel Using Three Kinds of Carboxylic Acids Supported by Iron(III) Chloride

2021 ◽  
Vol 11 (1) ◽  
pp. 104-111
Author(s):  
Jalil H. Kareem
Keyword(s):  
Hydrogen Peroxide ◽  
Carboxylic Acids ◽  
Diesel Fuel ◽  
Sulfur Removal ◽  
Oxidative Desulfurization ◽  
Reaction Times ◽  
Petroleum Products ◽  
Molar Ratio ◽  
Similar Reaction ◽  
Hydrotreated Diesel

Aqueous carboxylic acids (CA) are generally used as attractive catalytic extractants in the field of desulfurization of petroleum products. In the present study, a triple system consisting of CA-ferric chloride-hydrogen peroxide has been used for the removal of aromatic S-compounds from partially hydrotreated diesel by liquid−liquid oxidative-extraction. The influence of various operating parameters affecting the oxidative desulfurization was experimentally investigated. Formic acid (HCOOH), acetic acid (CH3COOH), and propanoic acid (CH3CH2COOH) as aqueous solutions with hydrogen peroxide and iron(III) chloride (FeCl3) as oxidant and catalytic agent, respectively, were used. All experiments were carried out at 55°C with different oxidant to sulfur mole ratios (nH2O2/nS) (15–36), CA to sulfur mole ratios (nCA/nS) (2–26), and oxidation reaction times (5–25 min). Within 25 min of the treatment, a maximum elimination of aromatic S-compounds of 65.1% was obtained when molar ratio of oxidant to sulfur (nH2O2/nS) was 36 and molar ratio of CA to sulfur (nCA/nS) was 26. Surface tension calculations for the CAs demonstrated that the average void radius of the acids has a pronounced effect on the fitting of S-compounds from diesel fuel into acids and is important to sulfur removal. Further, increasing the desulfurization efficiency was also energetically affected in the presence of ferric halide. The obtention of the sulfur removal ability value was noticeably higher than was achieved by employing similar reaction conditions in the absence of FeCl3.

Effect of transition metal oxides catalysts on oxidative desulfurization of model diesel

2012 ◽  
Vol 101 ◽  
pp. 78-84 ◽  
Author(s):  
Wan Azelee Wan Abu Bakar ◽  
Rusmidah Ali ◽  
Abdul Aziz Abdul Kadir ◽  
Wan Nur Aini Wan Mokhtar
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Oxidative Desulfurization ◽  
Model Diesel

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

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