scholarly journals The Direct Synthesis of Hydrogen Peroxide over AuPd Nanoparticles: An Investigation into Metal Loading

2021 ◽  
Author(s):  
Joseph Brehm ◽  
Richard J. Lewis ◽  
David J. Morgan ◽  
Thomas E. Davies ◽  
Graham J. Hutchings
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Oxidation State ◽  
Direct Synthesis ◽  
Catalytic Performance ◽  
Metal Loading ◽  
Subsequent Degradation ◽  
Small Nanoparticles

AbstractThe direct synthesis of H2O2 from molecular H2 and O2 over AuPd catalysts, supported on TiO2 and prepared via an excess chloride co-impregnation procedure is investigated. The role of Au:Pd ratio on the catalytic activity towards H2O2 formation and its subsequent degradation is evaluated under conditions that have previously been found to be optimal for the formation of H2O2. The combination of relatively small nanoparticles, of mixed Pd-oxidation state is shown to correlate with enhanced catalytic performance. Subsequently, a detailed study of catalytic activity towards H2O2 synthesis as a function of AuPd loading was conducted, with a direct correlation between catalytic activity and metal loading observed. Graphic Abstract

How does the Support Influence the Catalytic Activity of the Keggin Ion?

1996 ◽  
Vol 454 ◽  
Author(s):  
Zakiyyah Smith ◽  
Michael Palmieri ◽  
Nancy Buecheler ◽  
Susan A. Jansen
Keyword(s):  
Catalytic Activity ◽  
Carbon Materials ◽  
Solid Acid ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Heteropoly Acids ◽  
Keggin Ion ◽  
Oxide Substrates ◽  
Silica Matrices

AbstractHeteropoly acids, HPA are well known solid acid and oxidation catalysts that find application in hetergeneous and homogeneous reactions. In the former, surface area and stability problems are diminshed by supporting the HPA. Typical supports include oxide substrates and porous carbon materials. The HPA's show some instability on these supports however. In this work, we demonstrate that HPA encapsulated in sol-gel silica matrices show enhanced catalytic performance without compromising the catalytic activity of the HPA. In addition, the specific role of the support in the catalytic process is described as well.

scholarly journals Looking for the “Dream Catalyst” for Hydrogen Peroxide Production from Hydrogen and Oxygen

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 251 ◽  
Author(s):  
Federica Menegazzo ◽  
Michela Signoretto ◽  
Elena Ghedini ◽  
Giorgio Strukul
Keyword(s):  
Hydrogen Peroxide ◽  
Heterogeneous Catalysts ◽  
Direct Synthesis ◽  
Particle Morphology ◽  
Synthetic Methods ◽  
Side Reactions ◽  
Catalyst Morphology ◽  
And Performance ◽  
The Ideal

The reaction between hydrogen and oxygen is in principle the simplest method to form hydrogen peroxide, but it is still a “dream process”, thus needing a “dream catalyst”. The aim of this review is to analyze critically the different heterogeneous catalysts used for the direct synthesis of H2O2 trying to determine the features that the ideal or “dream catalyst” should possess. This analysis will refer specifically to the following points: (i) the choice of the metal; (ii) the metal promoters used to improve the activity and/or the selectivity; (iii) the role of different supports and their acidic properties; (iv) the addition of halide promoters to inhibit undesired side reactions; (v) the addition of other promoters; (vi) the effects of particle morphology; and (vii) the effects of different synthetic methods on catalyst morphology and performance.

Carbon Dioxide Hydrogenation to Methanol over Cu/ZnO-SBA-15 Catalyst: Effect of Metal Loading

2017 ◽  
Vol 380 ◽  
pp. 151-160 ◽  
Author(s):  
Sara Faiz Hanna Tasfy ◽  
Noor Asmawati Mohd Zabidi ◽  
Maizatul Shima Shaharun ◽  
Duvvria Subbarao ◽  
Ahmed Elbagir
Keyword(s):  
Catalytic Activity ◽  
Carbon Source ◽  
Active Sites ◽  
Low Cost ◽  
Fixed Bed ◽  
Textural Properties ◽  
Catalytic Performance ◽  
Hydrogenation Reaction ◽  
Supported Metal Catalysts ◽  
Metal Loading

Utilization of CO2 as a carbon source to produce valuable chemicals is one of the important ways to reduce the global warming caused by increasing CO2 in the atmosphere. Supported metal catalysts are crucial to produce clean and renewable fuels and chemicals from the stable CO2 molecules. The catalytic conversion of CO2 into methanol is recently under increased scrutiny as an opportunity to be used as a low-cost carbon source. Therefore, a series of the bimetallic Cu/ZnO-based catalyst supported by SBA-15 were synthesized via an impregnation technique with different total metal loading and tested in the catalytic hydrogenation of CO2 to methanol. The morphological and textural properties of the synthesized catalysts were determined by transmission electron microscopy (TEM), temperature programmed desorption, reduction, oxidation and pulse chemisorption (TPDRO), and N2-adsorption. The CO2 hydrogenation reaction was performed in a microactivity fixed-bed system at 250oC, 2.25 MPa, and H2/CO2 ratio of 3. Experimental results showed that the catalytic structure and performance were strongly affected by the loading of the active site. Where, the catalytic activity, the methanol selectivity as well as the space-time yield increased with increasing the metal loading until it reaches the maximum values at a metal loading of 15 wt% while further addition of metal inhibits the catalytic performance. The higher catalytic activity of 14% and methanol selectivity of 92% was obtained over a Cu/ZnO-SBA-15 catalyst with a total bimetallic loading of 15 wt%. The excellent performance of 15 wt% Cu/ZnO-SBA-15 catalyst is attributed to the presence of well dispersed active sites with small particle size, higher Cu surface area, and lower catalytic reducibility.

Nickel and cobalt phosphides as effective catalysts for oxygen removal of dibenzofuran: role of contact time, hydrogen pressure and hydrogen/feed molar ratio

2015 ◽  
Vol 5 (6) ◽  
pp. 3403-3415 ◽  
Author(s):  
A. Infantes-Molina ◽  
E. Gralberg ◽  
J. A. Cecilia ◽  
Elisabetta Finocchio ◽  
E. Rodríguez-Castellón
Keyword(s):  
Catalytic Activity ◽  
Contact Time ◽  
Hydrogen Pressure ◽  
Oxygen Removal ◽  
Molar Ratio ◽  
Metal Loading ◽  
Molar Ratios ◽  
Feed Molar Ratio

The catalytic activity of nickel and cobalt phosphides, with a metal loading of 5 wt.%, supported on silica was investigated in the hydrodeoxygenation reaction (HDO) of dibenzofuran (DBF) as a model oxygenated compound at different contact times, H2 pressures and H2/DBF molar ratios.

scholarly journals Properties and catalytic performance of sulphate-vanadia impregnated fumed silica as oxidative catalyst

2015 ◽  
Vol 11 (2) ◽  
Author(s):  
Nor Masdiana Zulkeple ◽  
Norhasyimah Mohd Kamal ◽  
Jamilah Mohd Ekhsan ◽  
Salasiah Che Me ◽  
Swee Ean Lim ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Charge Transfer ◽  
Surface Area ◽  
Sulphuric Acid ◽  
Fumed Silica ◽  
Catalytic Performance ◽  
Support Surface ◽  
High Catalytic Activity ◽  
Impregnation Method

A series of sulphate-vanadia impregnated fumed silica oxidative catalysts were synthesized via impregnation method. The samples were prepared by impregnation of 1 wt% of vanadium and 0.2 M of sulphuric acid onto fumed silica as support. Surface area of the silica supported samples were similar of 118 m2/g. UV-Vis DRS results showed existence of o supported V species and the charge transfer bands associated with O2- to V5+ in tetrahedral environments. Catalytic performance were evaluated via epoxidation of 1-octene to 1,2-epoxyoctane using hydrogen peroxide as an oxidant. It had been demonstrated that sulphate-vanadia impregnated fumed silica had high catalytic activity of 626 ± 0.2 mmol epoxide was produced after 24 h reaction. This may indicate that more oxidative sites were generated after the impregnation of V and sulphate onto the SiO2 matrixes.

scholarly journals The role of methoxy substituents in regulating the activity of selenides that serve as spirodioxyselenurane precursors and glutathione peroxidase mimetics

2016 ◽  
Vol 94 (4) ◽  
pp. 305-311 ◽  
Author(s):  
David J. Press ◽  
Thomas G. Back
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Glutathione Peroxidase ◽  
Methoxy Group ◽  
Steric Effects ◽  
Disulfide Formation ◽  
Excess Hydrogen ◽  
Meta Position ◽  
Methoxy Groups

A series of o-(hydroxymethyl)phenyl selenides containing single or multiple methoxy substituents was synthesized, and the rate at which each compound catalyzed the oxidation of benzyl thiol to its disulfide with excess hydrogen peroxide was measured. This assay provided the means for comparing the relative abilities of the selenides to mimic the antioxidant selenoenzyme glutathione peroxidase. The mechanism for catalytic activity involves oxidation of the selenides to their corresponding selenoxides with hydrogen peroxide, cyclization to spirodioxyselenuranes, followed by reduction with two equivalents of thiol to regenerate the original selenide with concomitant disulfide formation. A single p-methoxy group on each aryl moiety afforded the highest catalytic activity, while methoxy groups in the meta position had little effect compared to the unsubstituted selenide, and o-methoxy groups suppressed activity. The installation of multiple methoxy groups on each aryl moiety provided no improvement. These results can be rationalized on the basis of dominating mesomeric and steric effects of the p- and o-substituents, respectively.

Dual role of hydrogen peroxide on the oxidase-like activity of nanoceria and its application for colorimetric hydrogen peroxide and glucose sensing

RSC Advances ◽  
2016 ◽  
Vol 6 (65) ◽  
pp. 59939-59945 ◽  
Author(s):  
Ruochen Guo ◽  
Yanru Wang ◽  
Shaoxuan Yu ◽  
Wenxin Zhu ◽  
Fangqing Zheng ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Cerium Oxide ◽  
Glucose Sensing ◽  
Dual Role ◽  
Cerium Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Chromogenic Substrate

Nanoceria (cerium oxide nanoparticles) exhibits excellent catalytic activity towards chromogenic substrate 3,3,5,5-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2), which has been reported.

scholarly journals The role of peroxide in haem degradation. A study of the oxidation of ferrihaems by hydrogen peroxide

1978 ◽  
Vol 174 (3) ◽  
pp. 901-907 ◽  
Author(s):  
S B Brown ◽  
H Hatzikonstantinou ◽  
D G Herries
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Linear Dependence ◽  
Rate Constants ◽  
Experimental Error ◽  
Ph Dependence ◽  
Monomeric Species ◽  
Order Of Magnitude ◽  
Computer Based

The oxidation of ferrihaems by H2O2 was studied as a model for haem catabolism. Rates of ferrihaem oxidation were evaluated by using a new computer-based method that measures the loss in catalytic activity of the ferrihaem during oxidation. For protoferrihaem, deuteroferrihaem, coproferrihaem and mesoferrihaem, oxidation proceeded via the monomeric species and no dimer contribution was detectable. The pH-dependence of oxidation was studied in the range 6.5–11. Within experimental error, the data were compatible with an inverse linear dependence on [H+]. This was interpreted in terms of attack by HO2- on monomeric ferrihaem. The specific second-order rate constants for oxidation of monomeric species by HO2- were of the same order of magnitude for all the ferrihaems, and were in the sequence coproferrihaem greater than protoferrihaem greater than mesoferrihaem congruent to deuteroferrihaem. A model is suggested involving formation of a ferrihaem monomerperoxide complex, which may either dissociate with the formation of a peroxidatic intermediate or be involved in an intramolecular oxidation of the ferrihaem. Haem catabolism may occur via the same or a similar intermediate.

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