scholarly journals Kinetic and Mechanistic Study on Catalytic Decomposition of Hydrogen Peroxide on Carbon-Nanodots/Graphitic Carbon Nitride Composite

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 445 ◽  
Author(s):  
Zhongda Liu ◽  
Qiumiao Shen ◽  
Chunsun Zhou ◽  
Lijuan Fang ◽  
Miao Yang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Decomposition ◽  
Order Rate Constant ◽  
Catalytic Performance ◽  
Thermal Polymerization ◽  
Light Irradiation ◽  
Mechanistic Study ◽  
Carbon Nanodots ◽  
Environmental Catalyst ◽  
Adsorption Desorption

The metal-free CDots/g-C3N4 composite, normally used as the photocatalyst in H2 generation and organic degradation, can also be applied as an environmental catalyst by in-situ production of strong oxidant hydroxyl radical (HO·) via catalytic decomposition of hydrogen peroxide (H2O2) without light irradiation. In this work, CDots/g-C3N4 composite was synthesized via an electrochemical method preparing CDots followed by the thermal polymerization of urea. Transmission electron microscopy (TEM), X-Ray diffraction (XRD), Fourier Transform Infrared (FTIR), N2 adsorption/desorption isotherm and pore width distribution were carried out for characterization. The intrinsic catalytic performance, including kinetics and thermodynamic, was studied in terms of catalytic decomposition of H2O2 without light irradiation. The second-order rate constant of the reaction was calculated to be (1.42 ± 0.07) × 10−9 m·s−1 and the activation energy was calculated to be (29.05 ± 0.80) kJ·mol−1. Tris(hydroxymethyl) aminomethane (Tris) was selected to probe the produced HO· during the decomposing of H2O2 as well as to buffer the pH of the solution. The composite was shown to be base-catalyzed and the optimal performance was achieved at pH 8.0. A detailed mechanism involving the adsorb-catalyze double reaction site was proposed. Overall, CDots/g-C3N4 composite can be further applied in advanced oxidation technology in the presence of H2O2 and the instinct dynamics and the mechanism can be referred to further applications in related fields.

scholarly journals Insight into Active Centers and Anti-Coke Behavior of Niobium-Containing SBA-15 for Glycerol Dehydration

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 488
Author(s):  
Katarzyna Stawicka ◽  
Maciej Trejda ◽  
Maria Ziolek
Keyword(s):  
Coke Formation ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Silica Matrix ◽  
High Concentration ◽  
Active Centers ◽  
Acidic Sites ◽  
Glycerol Dehydration ◽  
Adsorption Desorption ◽  
Insight Into

Niobium containing SBA-15 was prepared by two methods: impregnation with different amounts of ammonium niobate(V) oxalate (Nb-15/SBA-15 and Nb-25/SBA-15 containing 15 wt.% and 25 wt.% of Nb, respectively) and mixing of mesoporous silica with Nb2O5 followed by heating at 500 °C (Nb2O5/SBA-15). The use of these two procedures allowed obtaining materials with different textural/surface properties determined by N2 adsorption/desorption isotherms, XRD, UV-Vis, pyridine, and NO adsorption combined with FTIR spectroscopy. Nb2O5/SBA-15 contained exclusively crystalline Nb2O5 on the SBA-15 surface, whereas the materials prepared by impregnation had both metal oxide and niobium incorporated into the silica matrix. The niobium species localized in silica framework generated Brønsted (BAS) and Lewis (LAS) acid sites. The inclusion of niobium into SBA-15 skeleton was crucial for the achievement of high catalytic performance. The strongest BAS were on Nb-25/SBA-15, whereas the highest concentration of BAS and LAS was on Nb-15/SBA-15 surface. Nb2O5/SBA-15 material possessed only weak LAS and BAS. The presence of the strongest BAS (Nb-25/SBA-15) resulted in the highest dehydration activity, whereas a high concentration of BAS was unfavorable. Silylation of niobium catalysts prepared by impregnation reduced the number of acidic sites and significantly increased acrolein yield and selectivity (from ca. 43% selectivity for Nb-25/SBA-15 to ca. 61% for silylated sample). This was accompanied by a considerable decrease in coke formation (from 47% selectivity for Nb-25/SBA-15 to 27% for silylated material).

scholarly journals Metal-Organic Frameworks in Oxidation Catalysis with Hydrogen Peroxide

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 283
Author(s):  
Oxana Kholdeeva ◽  
Nataliya Maksimchuk
Keyword(s):  
Hydrogen Peroxide ◽  
Liquid Phase ◽  
Selective Oxidation ◽  
Metal Organic Frameworks ◽  
Short Review ◽  
Catalytic Performance ◽  
Oxidation Catalysis ◽  
Catalyst Stability ◽  
Aqueous Hydrogen Peroxide ◽  
Metal Organic

In recent years, metal–organic frameworks (MOFs) have received increasing attention as selective oxidation catalysts and supports for their construction. In this short review paper, we survey recent findings concerning use of MOFs in heterogeneous liquid-phase selective oxidation catalysis with the green oxidant–aqueous hydrogen peroxide. MOFs having outstanding thermal and chemical stability, such as Cr(III)-based MIL-101, Ti(IV)-based MIL-125, Zr(IV)-based UiO-66(67), Zn(II)-based ZIF-8, and some others, will be in the main focus of this work. The effects of the metal nature and MOF structure on catalytic activity and oxidation selectivity are analyzed and the mechanisms of hydrogen peroxide activation are discussed. In some cases, we also make an attempt to analyze relationships between liquid-phase adsorption properties of MOFs and peculiarities of their catalytic performance. Attempts of using MOFs as supports for construction of single-site catalysts through their modification with heterometals will be also addressed in relation to the use of such catalysts for activation of H2O2. Special attention is given to the critical issues of catalyst stability and reusability. The scope and limitations of MOF catalysts in H2O2-based selective oxidation are discussed.

scholarly journals Mechanistic Study of the Conversion of Superoxide to Oxygen and Hydrogen Peroxide in Carbon Nanoparticles

2016 ◽  
Vol 8 (24) ◽  
pp. 15086-15092 ◽  
Author(s):  
Almaz S. Jalilov ◽  
Chenhao Zhang ◽  
Errol L. G. Samuel ◽  
William K. A. Sikkema ◽  
Gang Wu ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Nanoparticles ◽  
Mechanistic Study

Dual- vs single-active site mechanism in the catalytic decomposition of hydrogen peroxide

1978 ◽  
Vol 40 (6) ◽  
pp. 1277-1278 ◽  
Author(s):  
Mario Barteri ◽  
Marcello Farinella ◽  
Basilio Pispisa
Keyword(s):  
Hydrogen Peroxide ◽  
Active Site ◽  
Catalytic Decomposition

Preparation of Immobilized Chromium Schiff Base Complexes and their Catalytic Performance for Olefins Epoxidation

2014 ◽  
Vol 692 ◽  
pp. 240-244
Author(s):  
Gong De Wu ◽  
Xiao Li Wang ◽  
Zhi Li Zhai
Keyword(s):  
Hydrogen Peroxide ◽  
Schiff Base ◽  
Elemental Analysis ◽  
Catalytic Performance ◽  
Schiff Base Complexes ◽  
Metal Centers ◽  
Chemical Measurements ◽  
Physico Chemical ◽  
Immobilized Complexes ◽  
Mcm 41

A series of transition metal alanine-salicylaldehyde Schiff base chromium (III) complexes immobilized on MCM-41 were prepared and characterized by various physico-chemical measurements such as FIIR, XRD, HRTEM, N2 sorption and elemental analysis. The immobilized complexes were effective and stable catalysts for the epoxidation of styrene and cyclohexene with 30% hydrogen peroxide. Moreover, the metal centers were found to play important roles in the catalytic performance of immobilized complex catalysts.

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