Xn:Harmful;
144-62-7Relevant articles and documents
Site-Selective Growth of AgPd Nanodendrite-Modified Au Nanoprisms: High Electrocatalytic Performance for CO2 Reduction
Shan, Changsheng,Martin, Erin T.,Peters, Dennis G.,Zaleski, Jeffrey M.
, p. 6030 - 6043 (2017)
Environmental impacts of continued CO2 production have led to an increased need for new methods of CO2 removal and energy development. Nanomaterials are of special interest for these applications, because of their unique chemical and physical properties that allow for highly active surfaces. Here, we successfully synthesize AgPd nanodendrite-modified Au nanoprisms in various shapes (nanoprisms, hexagonal nanoplates, and octahedral nanoparticles) by selective metal deposition. This strategy involves coupling galvanic replacement between Ag layers in Au@Ag core-shell nanoprisms and H2PdCl4 with a coreduction process of silver and palladium ions. Synthesis of AgPd nanodendrite-tipped (4.14-11.47 wt % Pd) and -edged (25.25-31.01 wt % Pd) Au nanoparticles can be controlled simply by tuning the concentration of H2PdCl4. More importantly, these multicomponent AgPd nanodendrite-modified Au nanoparticles show exceptional electrocatalytic performance for CO2 reduction. AgPd nanodendrite-edged Au nanoprisms show more favorable potentials (-0.18 V vs RHE) than previously reported nanocatalysts for the reduction of CO2 to formate, and exhibit higher faradaic efficiencies (49%) than Au, Au@Ag, and AgPd nanodendrite-tipped Au nanoprisms in aqueous electrolytes. Moreover, AgPd nanodendrite-modified Au nanoprisms show much higher selectivity and faradaic efficiency for CO2 reduction to CO (85-87%) than Au and Au@Ag nanoprisms (43-64%) in organic electrolytes. The high performance of these particles for CO2 reduction is attributed to the unique structure of AgPd nanodendrite-modified Au nanoprisms and the synergistic effect of Ag having an affinity for CO2, efficient binding of hydrogen at Pd, and Au as a stable, conductive support. In addition, AgPd nanodendrite-edged Au nanoprisms show highly stable catalytic activity during long-term electrolyses (up to 12 h) and repetitive use. These exciting results indicate that AgPd nanodendrite-modified Au nanoparticles are promising for application in CO2 conversion into useful fuels.
The ozonization of model lignin compounds in aqueous solutions catalyzed by Mn(II) ions
Mitrofanova,Khudoshin,Lunin
, p. 1141 - 1146 (2010)
The influence of Mn(II) ions on the rate of the reaction between ozone and model lignin compounds, guaiacol and veratrole, was studied. The catalyst did not influence the rate of the destruction of the aromatic ring and intermediate ozonolysis products, compounds with conjugated double bonds, in acid media but substantially increased the rate of oxidation of saturated carboxylic acids, ketoacids, and aldehydes. Ozone consumption then increased from 2 to 5 moles per mole of the transformed substrate. A mechanism of the catalytic action of Mn(II) in reactions between ozone and the compounds studied was suggested.
Electrochemical reduction of CO2 in a mixed supercritical fluid
Abbott, Andrew P.,Eardley, Christopher A.
, p. 775 - 779 (2000)
The electroreduction of CO2 in the liquid and supercritical states was studied on both Pt and Pb electrode surfaces using a mixture of 1,1,1,2-tetrafluoroethane (HFC 134a) and CO2 solvent. A decrease in the reduction potential on both electrode materials was observed in the supercritical state compared with the liquid state. Platinum was far better than lead as a cathode material on which to reduce CO2 in supercritical CO2/HFC 134a mixture by both voltametric and bulk electrolysis experiments. The use of the supercritical mixture, rather than an aprotic liquid as electrochemical solvent, significantly improved the faradaic efficiency of oxalate formation at a Pt electrode, which can be due to the high CO2 concentration at the electrode surface in the mixture.
Studies on the oxygen atom transfer reactions of peroxomonosulfate: Oxidation of glycolic acid
Shailaja,Ramachandran
, p. 160 - 167 (2009)
The kinetics of oxidation of glycolic acid, an α-hydroxy acid, by peroxomonosulfate (PMS) was studied in the presence of Ni(II) and Cu(II) ions and in acidic pH range 4.05-5.89. The metal glycolate, not the glycolic acid (GLYCA), is oxidized by PMS. The rate is first order in [PMS] and metal ion concentrations. The oxidation of nickel glycolate is zero-order in [GLYCA] and inverse first order in [H+]. The increase of [GLYCA] decreases the rate in copper glycolate, and the rate constants initially increase and then remain constant with pH. The results suggest that the metal glycolate ML + reacts with PMS through a metal-peroxide intermediate, which transforms slowly into a hydroperoxide intermediate by the oxygen atom transfer to hydroxyl group of the chelated GLYCA. The effect of hydrogen ion concentrations on kobs suggests that the structure of the metal-peroxide intermediates may be different in Ni(II) and Cu(II) glycolates.
Kinetics and mechanism of the degradation and mineralization of acetone in dilute aqueous solution sensitized by the UV photolysis of hydrogen peroxide
Stefan, Mihaela I.,Hoy, Aitken R.,Bolton, James R.
, p. 2382 - 2390 (1996)
Acetone is a significant pollutant in contaminated groundwaters and industrial effluents. It can be treated by the UV/H2O2 process but only slowly. This study aims to understand the degradation mechanism and hence the reasons for slow treatment. The degradation of acetone was carried out in a UV reactor in the presence of ~16 mM H2O2 such that most of the UV was absorbed by H2O2. The decay of acetone was followed by gas chromatography, and the generation of intermediates (identified as acetic, formic, and oxalic acids) was followed by ion chromatography. Measurement of the total organic carbon indicated a complete carbon balance throughout the reaction ending in mineralization. A kinetic model, based on an assumed mechanism, was developed that generated a profile of reactants and intermediates in agreement with the experimental data, including the pH profile. The initial concentrations of acetone and hydrogen peroxide strongly affect the initial rate of acetone degradation, but no pH effect was observed in the range of 2-7. It is concluded that acetone treats slowly because intermediates build up to such a concentration that they compete significantly for hydroxyl radicals and also because the mechanism appears to involve some degree of acetone recycling.
Au-Pd/C catalysts for glyoxal and glucose selective oxidations
Hermans, Sophie,Deffernez, Aurore,Devillers, Michel
, p. 19 - 27 (2011)
A series of Au-Pd/C catalysts were prepared on an activated carbon named SX PLUS (SX+) by fixing the pH of impregnation in aqueous phase at an optimal value for maximizing the interactions between metals and surface. This bimetallic association leads to highly active catalysts in the oxidation of glyoxal into glyoxalic acid and of glucose into gluconic acid, with the activity correlated to high surface Pd/C ratios measured by XPS and the presence of small metallic Pd particles, even if gold was present as big crystallites. A cooperative effect between the two metals was evidenced on the yield in carboxylic acids in both reactions, which is believed to arise from an interface between the two metals even if they are mostly present as separated phases. The incorporation of Au on Pd rather than the opposite and the concomitant activation of both metals influence positively the catalytic performance. The use of NaBH4 as activating agent allowed the most active Au-Pd/C catalyst to be obtained, with similar performances to the best bimetallic Bi-Pd/C catalyst so far but without any metal leaching.
Monitoring of β-blockers ozone degradation via electrospray ionization mass spectrometry
Quispe, Cristina,Nachtigall, Fabiane M.,Fonseca, Maria Francesca R.,Alberici, Rosana M.,Astudillo, Luis,Villasen?or, Jorge,Eberlin, Marcos N.,Santos, Leonardo S.
, p. 919 - 928 (2011)
The structures of intermediate products of ozone degradation of different pharmaceutical compounds have been studied. Under the conditions employed, complete ozone degradation of nadolol was achieved after 100 min. The degradation products obtained in aqueous solution were characterized by electrospray ionization mass (and tandem mass) spectrometry (ESI-MS and ESI-MS/MS). The proposed mechanism for degradation, ozone attacks at the aniline amino group giving rise to nitro compounds and further degradation occurs via a series of oxidative processes. Continuous online monitoring by ESI-MS(/MS) with high accuracy mass measurements showed that ozone degradation of atenolol (ATE) and acebutolol (ACE) occurs via mechanisms similar to that of nadolol.
Improving the efficiency of Fenton reactions and their application in the degradation of benzimidazole in wastewater
Liu, Qinyao,Qian, Kun,Qi, Jinxu,Li, Chenru,Yao, Chen,Song, Wei,Wang, Yihong
, p. 9741 - 9748 (2018)
Reducing the quantity of sludge produced in Fenton reactions can be partly achieved by improving their efficiency. This paper firstly studies the effect of uniform deceleration feeding (ferrous iron and hydrogen peroxide) on the efficiency of a Fenton reaction by measuring the yield of hydroxyl radicals (OH) and chemical oxygen demand (COD) removal rate. The dynamic behavior of OH was also investigated. The results indicated that uniform deceleration feeding was the best feeding method compared with one-time feeding and uniform feeding methods when the same amount of Fenton reagents and the same reaction times were used. Besides, it was found the COD removal rate reached 79.3% when this method was applied to degrade 2-(a-hydroxyethyl)benzimidazole (HEBZ); this COD removal rate is larger than those when the other two modes were used (they reached 60.7% and 72.1%, respectively). The degradation pathway of HEBZ was determined using PL, UV-vis, FTIR, HPLC and GC-MS. Ultimately, HEBZ was decomposed into three small molecules (2-hydroxypropylamine, oxalic acid, and 2-hydroxypropamide). This research is of great significance for the application of Fenton reactions in wastewater treatment.
Atomically mixed Fe-group nanoalloys: Catalyst design for the selective electrooxidation of ethylene glycol to oxalic acid
Matsumoto, Takeshi,Sadakiyo, Masaaki,Ooi, Mei Lee,Yamamoto, Tomokazu,Matsumura, Syo,Kato, Kenichi,Takeguchi, Tatsuya,Ozawa, Nobuki,Kubo, Momoji,Yamauchi, Miho
, p. 11359 - 11366 (2015)
We demonstrate electric power generation via the electrooxidation of ethylene glycol (EG) on a series of Fe-group nanoalloy (NA) catalysts in alkaline media. A series of Fe-group binary NA catalysts supported on carbon (FeCo/C, FeNi/C, and CoNi/C) and monometallic analogues (Fe/C, Co/C, and Ni/C) were synthesized. Catalytic activities and product distributions on the prepared Fe-group NA catalysts in the EG electrooxidation were investigated by cyclic voltammetry and chronoamperometry, and compared with those of the previously reported FeCoNi/C, which clarified the contributory factors of the metal components for the EG electrooxidation activity, C2 product selectivity, and catalyst durability. The Co-containing catalysts, such as Co/C, FeCo/C, and FeCoNi/C, exhibit relatively high catalytic activities for EG electrooxidation, whereas the catalytic performances of Ni-containing catalysts are relatively low. However, we found that the inclusion of Ni is a requisite for the prevention of rapid degradation due to surface modification of the catalyst. Notably, FeCoNi/C shows the highest selectivity for oxalic acid production without CO2 generation at 0.4 V vs. the reversible hydrogen electrode (RHE), resulting from the synergetic contribution of all of the component elements. Finally, we performed power generation using the direct EG alkaline fuel cell in the presence of the Fe-group catalysts. The power density obtained on each catalyst directly reflected the catalytic performances elucidated in the electrochemical experiments for the corresponding catalyst. The catalytic roles and alloying effects disclosed herein provide information on the design of highly efficient electrocatalysts containing Fe-group metals. This journal is
Biocatalytic Production of Glyoxylic Acid
Seip, John E.,Fager, Susan K.,Gavagan, John E.,Gosser, Lawrence W.,Anton, David L.,DiCosimo, Robert
, p. 2253 - 2259 (1993)
The production of glyoxylic acid from glycolic (hydroxyacetic) acid has been demonstrated using the soluble enzymes glycolate oxidase and catalase as catalysts.Catalase was included as cocatalyst to decompose byproduct hydrogen peroxide, thus limiting peroxide-dependent formate production and glycolate oxidase deactivation.The addition to reaction mixtures of a primary amine capable of forming the hemiaminal or imine of glyoxylate resulted in an increase in the yield of glyoxylate; hemiaminal/imine mixtures of glyoxylate were not as readily oxidized to formate and carbon dioxide by hydrogen peroxide and also limited product inhibition of glycolate oxidase at high glyoxylate concentrations.A synergistic effect was observed when using Tris or ethylenediamine (EDA) with catalase, where increases in selectivity to glyoxylate were much greater than the sum of selectivities to glyoxylate obtained when using amine or catalase alone.The inclusion of EDA in reactions produced selectivities to glyoxylic acid in excess of 98-99percent at greater than 99percent conversion of 0.25M to 1.5M glycolic acid.The technical feasibility of a biocatalytic process for the production of glyoxylic acid was demonstrated by the preparation of ca. 0.50 kg of the acid in a series of 2.0-L batch reactions.
