- Catalytic Aerobic Oxidation of Biomass-based Furfural into Maleic Acid in Aqueous Phase with Metalloporphyrin Catalysts
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Catalytic oxidation of renewable furfural into valuable maleic acid in aqueous solutions using metalloporphyrin catalysts was investigated for the first time. The synthesized catalysts were characterized by FT-IR, UV–vis, 1H NMR, elemental analysis, and TGA. The catalysts varied in metal active sites and functional groups, which had different effects on their catalytic activity. Furthermore, the effects of temperatures, reaction time, catalyst loading, and oxygen pressure were studied in detail. Maleic acid could be achieved in 44% yield by using FeT(p-Cl)PPCl as catalyst under optimal conditions. Finally, FeT(p-Cl)PPCl could be reused in five consecutive runs without a significant loss of activity.
- Huang, Yi,Wu, Chunyan,Yuan, Wenwen,Xia, Yongmei,Liu, Xiang,Yang, Huamei,Wang, Haijun
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- Application of anodic oxidation, electro-Fenton and UVA photoelectro-Fenton to decolorize and mineralize acidic solutions of Reactive Yellow 160 azo dye
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The degradation of 100 cm3 of a solution with 0.167 mmol dm-3 Reactive Yellow 160 (RY160) azo dye in sulfate medium at pH 3.0 has been comparatively studied by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF). Trials were carried out with a stirred tank reactor equipped with a boron-doped diamond (BDD) anode and an air-diffusion cathode for H2O2 production, upon addition of 0.50 mmol dm-3 Fe2+ as catalyst in EF and PEF. The solution was slowly decolorized by AO-H2O2 because of the low rate of reaction of the azo dye and its colored products with hydroxyl radicals generated at the BDD anode from water oxidation. The color loss was enhanced in EF by the larger oxidation ability of hydroxyl radicals produced in the bulk from Fenton's reaction between added Fe2+ and generated H2O2, whereas the solution was more rapidly decolorized by PEF owing to the additional generation of hydroxyl radicals from the photolysis of Fe(III)-hydroxy complexes by UVA light. The relative mineralization ability of the processes also increased in the sequence AO-H2O2 -2. The influence of current density and RY160 concentration on the performance of all processes was assessed. Final carboxylic acids like maleic, fumaric, tartronic, acetic, oxalic, oxamic and formic were quantified by ion-exclusion HPLC. All these acids were totally removed by PEF, but the formation of small amounts of other highly recalcitrant products impeded the total mineralization. Chloride, sulfate, ammonium and, to a smaller extent, nitrate ions were released to the solution from the heteroatoms of the azo dye in all cases.
- Bedolla-Guzman, Alejandro,Sirés, Ignasi,Thiam, Abdoulaye,Peralta-Hernández, Juan Manuel,Gutiérrez-Granados, Silvia,Brillas, Enric
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- Fabrication of a stable Ti/Pb-TiOxNWs/PbO2 anode and its application in benzoquinone degradation
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To delay passivation of a titanium (Ti) substrate as well as enhance adhesion between an electrodeposited PbO2 coating and the Ti substrate, a titanium-lead composite oxide nanowire (Pb-TiOxNWs) intermediate layer was formed in situ on the surface of porous Ti by alkali etching, ion substitution, and high-temperature calcination. At the same time, Ti/PbO2 and Ti/TiO2NWs/PbO2 electrodes with porous Ti as a matrix were prepared for comparison. The surface structure and morphology of the prepared intermediate layer and the PbO2 coating were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The influences of the composite oxide intermediate layer on the electrochemical performance of the PbO2 electrode were analyzed by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and AC impedance spectroscopy (EIS). Accelerated lifetime tests were performed for electrodes with and without different intermediate layers. The results showed that PbOx was incorporated into the titanium dioxide three-dimensional network structure, resulting in formation of Pb-TiOxNWs. The surface of the Ti/Pb-TiOxNWs/PbO2 electrode was denser due to the smaller particle size of PbO2. The preferred crystal orientation of β(110) was observed for PbO2 deposited on Ti/Pb-TiOxNWs. The oxygen evolution potential reached a maximum of 2.19 V for Ti/Pb-TiOxNWs/PbO2. Accelerated life tests showed that compared with Ti/PbO2 and Ti/TiO2NWs/PbO2, the electrode life of Ti/Pb-TiOxNWs/PbO2 was increased by 91.7% and 35.3%, respectively. Therefore, it can be concluded that significantly improved morphology and electrochemical performance were achieved for titanium-based PbO2 electrodes by the addition of a Pb-TiOxNWs intermediate layer. In particular, the electrochemical stability of the PbO2 coating electrodes was improved markedly by the Pb-TiOxNWs intermediate layer. The electrodes were used for electrochemical oxidation of benzoquinone in wastewater (100 mg/L). It was found that chloride ions played a critical role in improving the current efficiency of electro-oxidative degradation. Under the same conditions, the COD removal rate in the presence of NaCl was 45% higher than in the presence of sulfate. The results of HPLC analysis of the intermediate products indicated that the oxidants electro-generated by chloride ions had stronger ring-opening and mineralization capabilities than those electro-generated by sulfate ions.
- Guo, Yingjuan,Tang, Changbin,Xue, Juanqin,Yu, Lihua,Zhang, Lihua
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- Decomposition of phenolic endocrine disrupting chemicals by potassium permanganate and γ-ray irradiation
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The decomposition of phenolic endocrine disrupting chemicals (P-EDCs), such as phenol, 4-t-butylphenol (BuP), and bisphenol A (BPA), in aqueous solutions by potassium permanganate (KMnO4) was studied, and its efficiency was compared with that of hydroxyl radicals (OH?) generated by 60Co γ-ray irradiation. Various organic acids and inorganic carbon were formed in the decomposition of P-EDCs due to either KMnO4 or OH?. They were formed via direct aromatic ring cleavage in the case of KMnO4 and via OH? addition-substitution reactions, followed by aromatic ring cleavage, in the case of OH?. Comparing the decrease in the P-EDCs based on the number of electrons, the amount of KMnO4 spent to completely eliminate BuP and BPA was comparable to that of OH?. Although three-times more KMnO4 was needed for phenol decomposition than OH?, the complete conversion of phenol into organic acids and inorganic carbon was achieved with 720 μM of electrons in both cases.
- Abe, Yasuhiro,Takigami, Machiko,Sugino, Kouji,Taguchi, Mitsumasa,Kojima, Takuji,Umemura, Tomonari,Tsunoda, Kin-Ichi
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- Reactions of Ozone with 1-(m-Substituted phenylazo)-2-naphthol-6-sulfonic Acids in Aqueous Solutions
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The substituent effect on the ozone decoloration of 1-(m-substituted phenylazo)-2-naphthol-6-sulfonic acids (PANSA) in aqueous solutions was investigated.Both the acidities of PANSA and the variation of the ozone decoloration rates of them increased compared to those of the corresponding 1-(m-substituted phenylazo)-2-naphthol-3,6-disulfonic acids (PANDSA).The relationships between the decoloration rates and the indexes (pKOH and ?m values) of the basicities of the dyes, however, indicated nearly the same characteristics between the data of these two series of dyes, and the ozone decoloration reactions of PANSA appeared to proceed by nearly the same mechanism as those of PANDSA.The changes of the keto-enol ratios of the dyes with their ozone decolorations suggested that the decoloration rates might rise as the reduction rates of their keto-enol ratios increased.It seems likely that the chief organic product that was finally produced in these resctions is oxalic acid.
- Onari, Yasuo
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- Heavy atom effects reveal diradical intermediates. I. An aqueous Diels- Alder reaction
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The aqueous Diels-Alder reaction between 2-methylfuran and maleic acid in water is 99.9% stereospecific. Addition of heavy but not light atom salts to the retrodiene reaction reduces the degree of stereospecificity significantly. Taking into account the relatively low concentration (3.5-7 M) of heavy atoms, and the rapid fall off of the heavy atom effect with distance, these results show that a large portion, if not all of the Diels Alder occurs via diradical intermediates.
- Telan, Leila A.,Firestone, Raymond A.
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- Degradation of the Cellulosic Key Chromophore 5,8-Dihydroxy-[1,4]-naphthoquinone by Hydrogen Peroxide under Alkaline Conditions
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5,8-Dihydroxy-[1,4]-naphthoquinone (DHNQ) is one of the key chromophores in cellulosic materials. Its almost ubiquitous presence in cellulosic materials makes it a target molecule of the pulp and paper industry's bleaching efforts. In the presented study, DHNQ was treated with hydrogen peroxide under alkaline conditions at pH 10, resembling the conditions of industrial hydrogen peroxide bleaching (P stage). The reaction mechanism, reaction intermediates, and final degradation products were analyzed by UV/vis, NMR, GC-MS, and EPR. The degradation reaction yielded C1-C4 carboxylic acids as the final products. Highly relevant for pulp bleaching are the findings on intermediates of the reaction, as two of them, 2,5-dihydroxy-[1,4]-benzoquinone (DHBQ) and 1,4,5,8-naphthalenetetrone, are potent chromophores themselves. While DHBQ is one of the three key cellulosic chromophores and its degradation by H2O2 is well-established, the second intermediate, 1,4,5,8-naphthalenetetrone, is reported for the first time in the context of cellulose discoloration.
- Zwirchmayr, Nele Sophie,Hosoya, Takashi,Henniges, Ute,Gille, Lars,Bacher, Markus,Furtmüller, Paul,Rosenau, Thomas
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- Photosensitized Cis-Trans Isomerization in Aqueous Solution. pH Effect on the Efficincy of Triplet-Triplet Energy Transfer to Maleic Acid
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Aromatic ketones, made water soluble by introduction of ionic substituents, photosensitize cis trans isomerization in the maleic-fumaric acid system.The photostationary-state cis/trans ratio depends on the triplet energy of the sensitizer and the pH of the medium.All sensitizers studied show a pH effect on the cis/trans ration which varies from 2.8 to 1.2 and is independent of whether the sensitizer is negatively or positively charged.Parallel quenching studies show the major part of this stems from a pH effect on the relative rates of energy transfer from the sensitizer to cis and trans acids.A smaller pH effect, in the opposite direction, is found with the rrelative rates of decay of the triplet to ground-state cis and trans isomers.Direct photoisomerization was also found to show this same pH effect in the decay of the lowest excited singlet to ground-state molecules.A rationalization is presented.
- Gupta, Atma,Mukhtar, Rehana,Seltzer, Stanley
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- Synthesis of maleic acid from renewable resources: Catalytic oxidation of furfural in liquid media with dioxygen
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Developing novel technologies to obtain fuel and organic chemicals from renewable resources has been the immediate issue in academic and industrial communities. The present work introduces a new route to synthesize maleic acid from the renewable furfural. The current data reveal that, using dioxygen as oxidant, the simple copper salts can catalyze oxidation of furfural to maleic acid in aqueous solution. The combination of copper nitrate with phosphomolybdic acid could achieve a 49.2% yield of maleic acid with selectivity of 51.7%. The major challenge for this route is how to avoid the polymerization of furfural to resins under oxidative conditions.
- Shi, Song,Guo, Huajun,Yin, Guochuan
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- Photocatalytic ozonation for degradation of 2-sec-butyl-4,6-dinitrophenol (DNBP) using titanium dioxide: Effect of operational parameters and wastewater treatment
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The results of degradation efficiency of 2-sec-butyl-4,6-dinitrophenol (DNBP) in a batch system by various advanced oxidation processes revealed the order of TiO2/UV/O3 > TiO2/O3 > UV/O3 > O3 > UV/TiO2. All processes followed pseudo-first order kinetics. The influence of operational parameters such as initial pH, initial concentration of DNBP, ozone and catalyst dosage on the TiO2/UV/O3 process, which was the most significant investigated method. The ozone dosage was found to have the noticeable impact on the process; however, initial pH and TiO2 dosage were less effective. The mineralization of 40 mg/L of DNBP and petrochemical wastewater under the obtained optimal conditions was monitored by total organic carbon and chemical oxygen demand, respectively. The results demonstrated that the TiO 2/UV/O3 process was a very effective method for degradation and mineralization of DNBP in aqueous solutions and industrial wastewater. The degradation intermediates were identified by GC-MS.
- Mousanejad,Khosravi,Tabatabaii,Khataee,Zare
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- An electrocatalytic route for transformation of biomass-derived furfural into 5-hydroxy-2(5H)-furanone
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Development of efficient strategies for biomass valorization is a highly attractive topic. Herein, we conducted the first work on electrocatalytic oxidation of renewable furfural to produce the key bioactive intermediate 5-hydroxy-2(5H)-furanone (HFO). It was demonstrated that using H2O as the oxygen source and metal chalcogenides (CuS, ZnS, PbS, etc.) as electrocatalysts, the reaction could proceed efficiently, and the CuS nanosheets prepared in this work showed the best performance and provided high HFO selectivity (83.6%) and high conversion (70.2%) of furfural. In addition, the CuS electrocatalyst showed long-term stability. Mechanism investigation showed that furfural was oxidized to HFO via multistep reactions, including C-C cleavage, subsequent ring opening and oxidation, and intramolecular isomerization.
- Wu, Haoran,Song, Jinliang,Liu, Huizhen,Xie, Zhenbing,Xie, Chao,Hu, Yue,Huang, Xin,Hua, Manli,Han, Buxing
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- A new catalyst for the selective oxidation of butane and propane
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A niobium and pyridine salt of molybdo(vanado)phosphoric acid (see formula) leads to a catalyst that achieves excellent yield and productivity for both the conversion of propane into acrylic acid and N-butane into maleic acid. The catalyst is active under
- Davis, Mark E.,Dillon, Christopher J.,Holles, Joseph H.,Labinger, Jay
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- Active sites in vanadia/titania catalysts for selective aerial oxidation of β-picoline to nicotinic acid
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Vanadia/titania catalysts with varying vanadium content were prepared by impregnation using three different titania carrier materials of varying surface area. The structure of active vanadium species for β-picoline oxidation was investigated. Vanadium is mainly in the +5 oxidation state as revealed by electron paramagnetic resonance (EPR) and 51V magic-angle spinning nuclear magnetic resonance (51V MAS NMR) spectroscopy techniques. Diffuse reflectance UV-visible (DRUV-vis) spectroscopy and spectral deconvolution enabled identification of at least five different types of vanadium oxide species in these catalysts: monomeric tetrahedral VO3-4, polymeric distorted tetrahedral VO-3, square pyramidal V2O5, octahedral V2O2-6 and V4+ oxide species. While both VO3-4 and VO-3 species are active in β-picoline oxidation, the latter having a distorted tetrahedral geometry yielded the desired products-picolinaldehyde and nicotinic acid. High surface area, anatase structure for the support and dispersed, distorted tetrahedral vanadium oxide species are the key parameters determining the activity and selectivity of these oxidation catalysts.
- Srinivas, Darbha,Hoelderich, Wolfgang F.,Kujath, Steffen,Valkenberg, Michael H.,Raja, Thirumalaiswamy,Saikia, Lakshi,Hinze, Ramona,Ramaswamy, Veda
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- Robust selenium-doped carbon nitride nanotubes for selective electrocatalytic oxidation of furan compounds to maleic acid
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Selective oxidation of biomass-derived furan compounds to maleic acid (MA), an important bulk chemical, is a very attractive strategy for biomass transformation. However, achieving a high MA selectivity remains a great challenge. Herein, we for the first time successfully designed and fabricated Se-doped graphitic carbon nitride nanotubes with a chemical formula of C3.0N-Se0.03. The prepared C3.0N-Se0.03 was highly efficient for electrocatalytic oxidation of various biomass-derived furan compounds to generate MA. At ambient conditions, the MA yield could reach 84.2% from the electro-oxidation of furfural. Notably, the substituents on the furan ring significantly affected the selectivity to MA, following the order: carboxyl group > aldehyde group > hydroxyl group. Detailed investigation revealed that Se doping could tune the chemical structure of the materials (e.g., C3.0N-Se0.03 and g-C3N4), thus resulting in the change in catalytic mechanism. The excellent performance of C3.0N-Se0.03 originated from the suitable amount of graphitic N and its better electrochemical properties, which significantly boosted the oxidation pathway to MA. This work provides a robust and selective metal-free electrocatalyst for the sustainable synthesis of MA from oxidation of biomass-derived furan compounds. This journal is
- Huang, Xin,Song, Jinliang,Hua, Manli,Chen, Bingfeng,Xie, Zhenbing,Liu, Huizhen,Zhang, Zhanrong,Meng, Qinglei,Han, Buxing
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- Photochemical transformation of maleic anhydride in aqueous solutions
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Solutions of maleic anhydride, occurring in the waste water of the organic chemical industry in the Koper area (Slovenia) and subsequently entering the river Rizana and the Bay of Koper (Gulf of Trieste, northern Adriatic), in distilled, riverine and artificial and natural sea water were photolyzed using photochemical reactors and exposure to sunlight. The transformation of maleic anhydride under artificial light proceeds first through hydrolysis to maleic acid and then photochemical isomerization of maleic acid to fumaric acid, its partial decarboxylation and polymerization. The polymeric product formed is complex consisting of chains with methylene and methine groups and these chains connected by ether and ester bonds. The average molecular weights of the polymers formed were distributed in a broad range lower than 4200. The izomerization is catalyzed by inorganic ions and to a lesser extent by dissolved organic matter (DOM) while polymerization is inhibited by inorganic ions but DOM has a negligible effect. The quantum yields ranged between 0.03-0.04. The influence of the air atmosphere was negligible.
- Bajt,Sket,Faganeli
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- Synthesis, analysis and possibility application of cyclic and linear forms of poly(aspartic acid) synthesized under microwave irradiation
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In this paper a new original method of synthesis of poly(aspartic acid) (PAA) from aspartic acid (AA) or maleic anhydride under microwave irradiation is presented. The syntheses carried out mainly without the catalyst, received higher yield in comparison for conventional method. PAA has been characterized by nuclear magnetic resonance (1H NMR, 13C NMR), infrared spectroscopy (FT-IR) and termogravimetric analysis (Tg). Obtained polymer we used for several diversified applications, such as, medicine, agriculture and catalyst for oxidation reactions. Taylor & Francis Group, LLC.
- Pielichowski,Polaczek,Hebda
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- Hydrogen Peroxide Oxygenation of Furan-2-carbaldehyde via an Easy, Green Method
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Derivatives of 2(5H)-furanone (γ-crotonolactone) are important intermediate synthetic products with a wide range of biological effects that have become widely used in the pharmaceutical industry, medicine, and veterinary medicine, in particular in the prevention and treatment of fish diseases. However, the environmental issue of obtaining these compounds while reducing the negative impact on the surrounding environment remains relevant. This article describes for the first time a method of γ-crotonolactone synthesis that is based on the concept of green chemistry. Synthesis is carried out under mild conditions using nontoxic reagents by furfural oxidation. For the first time, a mixture of hydrogen peroxide and acetic acid was used for the oxidation of furfural in a ratio of 1:0.05. A mixture of organic acids (succinic, maleic, fumaric, formic, and cinnamic acids), obtained as a byproduct in the synthesis of γ-crotonolactone, can be used as a highly effective, ecofriendly organic fertilizer or in a preparation with a stimulating effect.
- Zvarych, Viktor,Nakonechna, Anna,Marchenko, Mykhailo,Khudyi, Oleksii,Lubenets, Vira,Khuda, Lidiia,Kushniryk, Olga,Novikov, Volodymyr
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- Polarographic study of reactions in the system 2-furaldehyde-hydrogen peroxide-NaVO3
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The oxidation of 2-furaldehyde to β-formylacrylic acid in 0.1 N HClO4 containing hydrogen peroxide and sodium vanadate was studied by polarography using a dropping mercury electrode. The conversion of 2-furaldehyde and the yield of the products were found to depend on the reactant ratio. A mechanism was proposed which includes preliminary complex formation between the reactants.
- Strizhov,Poskonin,Oganova,Badovskaya
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- Hetero-mixed TiO2-SnO2 interfaced nano-oxide catalyst with enhanced activity for selective oxidation of furfural to maleic acid
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Herein we report on the catalytic activity of hetero-mixed TiO2-SnO2 nano-oxide catalyst for the selective liquid-phase oxidation of furfural to maleic acid using H2O2 oxidant. The high surface area and strong interaction of the two oxides with modified electronic structure manifested enhanced effective oxygen vacancies, and redox activity performance of the TiO2-SnO2 catalyst for furfural oxidation reaction. The structure of the catalyst was investigated by the powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transition electron microscopy (HRTEM), electron paramagnetic resonance (EPR) and Brunauer-Emmett-Teller (BET) surface area analyser techniques. The interfaced TiO2-SnO2 oxide catalyst was more catalytically active than its single counterpart SnO2 and TiO2 oxides to give a furfural conversion of 96.2% at up to 63.8% yield of maleic acid. The catalytic performance shown by TiO2-SnO2 present encouraging prospects for an economical solid metal oxide catalyst to access biobased maleic acid from renewable biomass-derived furfural.
- Malibo, Petrus M.,Makgwane, Peter R.,Baker, Priscilla G.L.
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- The effect of metal ions on the reaction of hydrogen peroxide with Kraft lignin model compounds
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Peroxide bleaching is significantly affected by transition and alkaline earth metals. Isolating the effects of different transition and alkaline earth metals on the reactions of peroxide with different representative lignin structures allows the separation of the positive from the negative contributions of these metal ions. In this work, five monomeric or dimeric phenolic lignin model compounds were treated with alkaline hydrogen peroxide in the absence or presence of Mn2+, Cu2+, Fe3+, and Mg2+. We followed the disappearance of the starting material and the progress of demethylation, radical coupling and oxalic acid formation were followed. Transition metals increased the reactivities of all the lignin model compounds with hydrogen peroxide in the order Mn2+ > Cu2+ > Fe3+, which is the same as the order of activity toward peroxide decomposition while Mg2+ stabilized the system. Demethylation, radical coupling, and oxalic acid formation were all increased by the presence of transition metals in the system and decreased by the addition of Mg2+. The acceleration of the total degree of reaction and of the demethoxylation reactions improves peroxide bleaching, but the increase in the radical coupling reactions can affect the further bleachability of pulp while the increase in the formation of oxalic acid could lead to a greater probability of scaling.
- Sun, Yujun,Fenster, Michael,Yu, Annie,Berry, Richard M.,Argyropoulos, Dimitris S.
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- In-situ fabrication of 0D/2D NiO/Bi12O17Cl2 heterojunction towards high-efficiency degrading 2, 4-dichlorophenol and mechanism insight
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2, 4-dichlorophenol (2, 4-DCP) as a persistent pollutant is frequently detected in water environments, complete eradication of trace which in water is an important task. Hence, a 0D/2D NiO/Bi12O17Cl2 heterojunction was achieved by in-situ fabrication of NiO nanodots on Bi12O17Cl2 nanosheets, which obviously improved the physical, optical and photoelectrochemical properties. The photocatalytic degradation activity of 0D/2D NiO/Bi12O17Cl2 heterojunction was boosted dramatically, which originated from the improved transfer and separation efficiency of charge carriers owing to the formation of Z-scheme heterostructure between NiO and Bi12O17Cl2. The possible photocatalytic reaction mechanism including migration behaviors of charge carriers, generation of reactive species and degradation intermediate products were revealed in depth. This work provides the valuable experiences for designing and fabricating otherwise 0D/2D heterojunction photocatalysts in the application of environmental treating fields.
- Song, Ning,Li, Jiaming,Li, Chunmei,Zhou, Pengjie,Jiang, Enhui,Zhang, Xiaoxu,Liu, Chunbo,Wu, Zhichen,Zheng, Hang,Che, Guangbo,Dong, Hongjun
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- Degradation of 2,4-dichlorophenol from aqueous using UV activated persulfate: Kinetic and toxicity investigation
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2,4-DCP is a high-toxicity phenol compound, which is difficult to remove, harmful to the health of people and seriously influences the aquatic ecosystems. In this study, the degradation of 2,4-DCP using UV/persulfate (UV/PS) process was investigated for the first time. The results showed pseudo-first-order rate constants of 2,4-DCP photo-degradation by UV/PS was 35.1 × 10-3 min-1. The reaction rate constants increased with pH increasing from 5 to 7 and then decreased at pH 8. Different anions (Cl-, HCO3- and NO3-) in water presented different effects on the photo-degradation reaction. The photo-degradation rates of 2,4-DCP in three actual water conditions (Xidong water works, Xijiu reservoir, Henshan reservoir) were higher than in the ultrapure water. Two possible (hydroxylated and dechlorinated) pathways for the degradation of 2,4-DCP by UV/PS were proposed. The luminescent bacteria inhibition rate greatly decreased with the concentration of 2,4-DCP decreasing in the reaction process.
- Chen, Juxiang,Gao, Naiyun,Lu, Xian,Xia, Meng,Gu, Zhenchuan,Jiang, Chuang,Wang, Qiongfang
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p. 100056 - 100062
(2016)
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- Highly efficient formic acid-mediated oxidation of renewable furfural to maleic acid with H2O2
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Maleic acid and its anhydride are important intermediates in the chemical industry produced on a multimillion tonne-scale annually. The synthesis of maleic acid/anhydride from renewable biomass resources such as furfural and 5-hydroxymethylfurfural is highly desirable for the sustainability of human society. Most of the previously reported processes for maleic acid/anhydride synthesis from biomass suffer from low efficiency, complicated conditions and poor catalyst recyclability. Herein, we demonstrate a highly efficient and simple system for the synthesis of maleic acid from furfural. An excellent yield (95%) of maleic acid was achieved under mild conditions in this very simple system which requires only H2O2 as an oxidant in formic acid solvent. Under similar conditions, an 89% yield of maleic acid was achieved from biomass-derived 5-hydroxymethylfurfural. This study presents a novel synthetic method and a promising process for maleic acid production from renewable biomass resources.
- Li, Xiukai,Ho, Ben,Lim, Diane S. W.,Zhang, Yugen
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- A biomass-derived metal-free catalyst doped with phosphorus for highly efficient and selective oxidation of furfural into maleic acid
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The present work introduces an extremely simple and eco-friendly strategy for the highly selective synthesis of maleic acid (MA)viaoxidation of renewable furfural using the abundant biomass-derived P-C-Tcatalyst. The P-C-Tcarbon catalyst was metal-free and prepared by the pyrolyzation of phytic acid, which is a ubiquitous natural molecule containing phosphorus. Extensive characterization was carried out to reveal the morphological and elemental properties of the synthesized P-C-Tseries. The effect of the annealing temperature of pyrolyzing phytic acid on the properties of the yielded P-C-Tand subsequent catalytic performance was also explored. The catalytic oxidation of furfural to MA was carried out in the presence of H2O2within an aqueous system. The reaction conditions including the catalyst loading, H2O2concentration, reaction temperature and duration were further optimized. It was found that P-C-600 exhibited a remarkable catalytic activity for MA synthesis from furfural oxidation with a maximum yield of 76.3% achieved in water. The excellent catalytic performance of P-C-600 was attributed to its unique atomic layered structure and suitable acidity. P-C-600 could also be re-used for at least six runs without any obvious decrease in its catalytic performance. The intrinsic advantages of green synthesis, low cost, and excellent catalytic performance in the catalytic oxidation of furfural to MA suggested that P-C-600 would be a promising catalyst in future industrial applications for MA synthesis in a green manner.
- Zhang, Huifa,Wang, Shaolin,Zhang, Huixian,Clark, James H.,Cao, Fahai
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- Degradation of chlorinated phenols in water in the presence of H 2O2 and water-soluble μ-nitrido diiron phthalocyanine
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Efficient disposal of pollutants is a key problem in the environmental context. In particular, chlorinated aromatic compounds are recalcitrant to biodegradation and conventional treatment methods. Iron phthalocyanines were previously shown to be efficient catalysts for the oxidative degradation of chlorinated phenols considered as priority pollutants. We have recently discovered μ-nitrido diiron phthalocyanines as powerful oxidation catalysts. Herein, we evaluate these emerging catalysts in the oxidation of chlorinated phenols in comparison with conventional mononuclear complex. Catalytic performance of iron tetrasulfophthalocyanine (FePcS) and corresponding μ-nitrido dimer [(FePcS)2N] have been compared in the oxidation of chlorinated phenols by hydrogen peroxide in water. The oxidative degradation of 2,6-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) has been studied. The (FePcS)2N exhibited better catalytic properties than mononuclear FePcS in terms of conversion and mineralization (transformation of organic chlorine to Cl- and decrease of total organic carbon due to the formation of CO2). Kinetics of the DCP oxidation indicated that different reaction mechanisms are involved in the presence of FePcS and (FePcS)2N. The high catalytic activity of (FePcS)2N in the degradation and mineralization of chlorinated phenols make μ-nitrido diiron phthalocyanines promising catalyst to apply also in environmental remediation.
- Colomban, Cédric,Kudrik, Evgeny V.,Afanasiev, Pavel,Sorokin, Alexander B.
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- Oxidation of p-hydroxybenzoic acid by Fenton's reagent
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Fenton's reagent has been shown to be a feasible technique to treat phenolic-type compounds present in a variety of food processing industry wastewaters. A model compound, p-hydroxybenzoic acid was oxidised by continuously pumping two solutions of ferrous iron and hydrogen peroxide. Typical operating variables like reagent feeding concentrations and flowrate, temperature and pH were studied. A mechanism of reactions based on the classical Fenton's chemistry was assumed, and computed concentration profiles of the parent compound, ferrous ion and dihydroxybenzene were compared to experimental results. The model qualitatively predicted the influence of several operating variables, however, calculated results suggested the presence of parallel routes of substrate elimination and/or a initiating rate constant with a higher value. The low efficiency of a well-known hydroxyl radical scavenger (tert-butyl alcohol) also supports the contribution of oxidising species different from the hydroxyl radical to substrate removal. Further evidence of the presence of reactions different from the hydroxyl radical oxidation was observed from comparison of the simultaneous Fenton's or UV/H2O2 oxidations of p-hydroxybenzoic acid, tyrosol and p-coumaric acid. (C) 2000 Elsevier Science Ltd. Fenton's reagent has been shown to be a feasible technique to treat phenolic-type compounds present in a variety of food processing industry wastewaters. A model compound, p-hydroxybenzoic acid was oxidized by continuously pumping two solutions of ferrous iron and hydrogen peroxide. Typical operating variables like reagent feeding concentrations and flowrate, temperature and pH were studied. A mechanism of reactions based on the classical Fenton's chemistry was assumed, and computed concentration profiles of the parent compound, ferrous ion and dihydroxybenzene were compared to experimental results. The model qualitatively predicted the influence of several operating variables, however, calculated results suggested the presence of parallel routes of substrate elimination and/or a initiating rate constant with a higher value. The low efficiency of a well-known hydroxyl radical scavenger (tert-butyl alcohol) also supports the contribution of oxidizing species different from the hydroxyl radical to substrate removal. Further evidence of the presence of reactions different from the hydroxyl radical oxidation was observed from comparison of the simultaneous Fenton's or UV/H2O2 oxidations of p-hydroxybenzoic acid, tyrosol and p-coumaric acid.
- Rivas,Beltran,Frades,Buxeda
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- Remarkable Reactivity of Boron-Substituted Furans in the Diels-Alder Reactions with Maleic Anhydride
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The reactivity of boron-substituted furans as dienes in the Diels-Alder reaction with maleic anhydride has been investigated. Gratifyingly, the furans with boryl substituents at C-3 gave the exo cycloadduct exclusively with excellent yields. In particular, the potassium trifluoroborate exhibited outstanding reactivity at room temperature. Theoretical calculations suggested that the trifluoroborate group is highly activating and also that the thermodynamics is the main factor that determines whether the products can be obtained efficiently or not.
- Medrán, Noelia S.,Dezotti, Federico,Pellegrinet, Silvina C.
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- Synthesis of maleic and fumaric acids from furfural in the presence of betaine hydrochloride and hydrogen peroxide
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Here we report the successful valorisation of furfural into maleic acid (MA) and fumaric acid (FA) with a total yield above 90% using an aqueous solution of betaine hydrochloride (BHC) in the presence of hydrogen peroxide. BHC can be recycled for at least 4 cycles and it can be used to directly convert xylose to MA and FA.
- Araji,Madjinza,Chatel,Moores,Jér?me,De Oliveira Vigier
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- Effect of Al and Ce on Zr-pillared bentonite and their performance in catalytic oxidation of phenol
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Catalysts based on pillared clays with Zr and/or Al and Ce–Zr and/or Al polycations have been synthesized from a Tunisian bentonite and tested in catalytic oxidation of phenol at 298 K. The Zr-pillared clay showed higher activity than the Al-one in phenol oxidation. Mixed Zr–Al pillars lead to an enhancement of the catalytic activity due to the modification of the zirconium properties. The clays modified with Ce showed high conversions of phenol and TOC thus showing to be very selective towards the formation of CO2 and H2O.
- Mnasri-Ghnimi, Saida,Frini-Srasra, Najoua
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- Deep eutectic solvent (DES) as both solvent and catalyst for oxidation of furfural to maleic acid and fumaric acid
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Efficient conversion of furfural to valuable chemicals is attracting attention because it is one of the bulk feedstocks in biomass refinery. Maleic acid (MA) and fumaric acid (FA) are two types of bulk monomers that can be prepared from furfural. Here, a simple method was developed to oxidize furfural to both MA and FA in a green deep eutectic solvent (DES). DES contained oxalic acid and choline chloride (ChCl); oxalic acid worked as both the main content of the solvent and acidic catalyst for the conversion. It was found that the conversion of furfural could reach 100%, while the yield of MA and FA reached 95.7% under a mild reaction temperature of 50 °C, which provided a green and efficient route for the synthesis of valuable monomers from furfural.
- Ni, Yong,Bi, Zhihao,Su, Hui,Yan, Lifeng
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- Facile preparation of a Ti/α-PbO2/β-PbO2 electrode for the electrochemical degradation of 2-chlorophenol
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A Ti/α-PbO2/β-PbO2 electrode with high stability was prepared and examined toward the electrochemical degradation of 2-chlorophenol. Scanning electron microscopy analysis revealed that Ti/α-PbO2/β-PbO2 had a cauliflower morphology comprising small β-PbO2 crystals. The 2-chlorophenol removal rate using the Ti/α-PbO2/β-PbO2 electrode was 100% after 180 min of electrolysis under optimal conditions, which were selected based on the orthogonal test method, i.e., initial concentration of 2-cholorophenol = 50 mg/L, concentration of Na2SO4 = 0.1 mol/L, temperature = 35°C, and anode current density = 20 mA/cm2. Kinetic analyses demonstrated that the electrochemical oxidation of 2-chlorophenol on the Ti/α-PbO2/β-PbO2 electrode followed pseudo-first order kinetics.
- Zhang, Qianli,Guo, Xinyan,Cao, Xiaodan,Wang, Dongtian,Wei, Jie
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- Degradation of Phenol and Salicylic Acid by Ultraviolet Radiation/Hydrogen Peroxide/Oxygen
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Based on the oxidation reactions of u.v. radiation/hydrogen peroxide/oxygen with either phenol or salicylic acid a spectra library was established. The reaction products contain hydroxylated phenols, benzoquinone and aliphatic acids with up to six carbon atoms. Many of the substances have been identified by means of chromatography and spectra comparison. From the observed concentrations of the substances and the known reaction mechanisms the following course of reaction has been postulated. The first reaction step is the hydroxylation of the aromatic ring. Further oxidation occurs via abstraction of a hydrogen atom to form 1,2-benzoquinone which is cleaved to form muconic acid. The cleavage of the muconic acid by u.v. radiation/hydrogen peroxide/oxygen leads to maleic acid, fumaric acid and oxalic acid. The degradation of oxalic acid leads to formic acid and finally to carbon dioxide. The hydroxylation of the double bond of the maleic or fumaric acid and the abstraction of a hydrogen atom produces malic acid. The reactions can be seen as essential step in the photochemical transformation of refractory substances into biodegradable ones.
- Scheck, Christoph K.,Frimmel, Fritz H.
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- Key role of the phosphate buffer in the H2O2 oxidation of aromatic pollutants catalyzed by iron tetrasulfophthalocyanine
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The non-innocent role of the phosphate buffer has been established in the H2O2 oxidative decomposition of 2,4,6-trichlorophenol (TCP), a benchmark pollutant, catalyzed by iron(III) tetrasulfophthalocyanine (FePcS). The catalytic oxidation of several other substrates (3,5-dichloroaniline, tetrachlorocatechol, di-tert-butylcatechol and catechol itself) has been carried out, also demonstrating a crucial influence of the phosphate buffer in the decomposition of the chlorinated substrates. Three hypotheses have been studied: modification of the ionic strength, formation of a peroxyphosphate species, or catalysis by a peroxyphosphate-FePcS complex. Supports for the latter proposal have been obtained from several experimental results and attempts have been made to characterize this putative catalytic intermediate. This intermediate derivative has also been generated from the reaction of FePcS with peroxymonophosphoric acid (PMPA) and its catalytic activity has been checked on the decomposition of TCP in different reaction mixture. A short mechanistic study has allowed different reaction pathways to be proposed, dependent on the active species implicated.
- Sanchez, Muriel,Hadasch, Anke,Fell, Rainer T.,Meunier, Bernard
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- Electrochemical oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid (Fdca) in acidic media enabling spontaneous fdca separation
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2,5-Furandicarboxylic acid (FDCA) has become an increasingly desirable platform chemical to replace terephthalic acid in the production of a variety of polymeric materials, including polyethylene terephthalate. FDCA can be produced by the oxidation of 5-hydroxymethylfurfural (HMF), which can be derived from cellulosic biomass. Oxidation of HMF to FDCA is typically performed under basic conditions. Separation of FDCA is most easily accomplished by lowering the pH until FDCA is insoluble and filtering it from solution. In a large-scale process, this would lead to a high operating cost to purchase the required acid and base and to dispose of the resulting salt waste. In this study, electrochemical oxidation of HMF was carried out in acidic media by using a manganese oxide (MnOx) anode to remove the need to vary the pH to separate FDCA. The MnOx anode afforded a FDCA yield of 53.8 % in a pH 1 H2SO4 solution, in which FDCA precipitation occurred spontaneously from the same reaction solution without altering the pH or other aspects of the solution composition. Electrochemical oxidation in acidic media offers a new pathway to convert HMF into maleic acid, which is another desirable biomass-derived platform molecule. The performance of the MnOx anode was investigated in comparison with that of a Pt anode to identify unique electro-catalytic properties of the MnOx anode for HMF oxidation.
- Kubota, Stephen R.,Choi, Kyoung-Shin
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- Catalyst for catalytic oxidation of furfural to prepare maleic acid and application thereof
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A catalyst for catalytic oxidation of furfural to prepare maleic acid, relating to the technical field of renewable energy. The catalyst is a mixture of a bromide and a base. A method for preparing the catalyst in catalytic oxidation of furfural to prepare maleic acid. The method includes: mixing the furfural, the bromide-base, an oxidant and a solvent to carry out a reaction to obtain the maleic acid. The present invention has the advantages that the method has a relatively high conversion rate of furfural and a relatively high yield of maleic acid, the conversion rate of furfural is up to 99%, the yield of maleic acid is up to 68.04%; and the catalyst has a high catalytic selectivity and reusability.
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Page/Page column 10-12
(2022/02/10)
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- Ordered mesoporous carbon as an efficient heterogeneous catalyst to activate peroxydisulfate for degradation of sulfadiazine
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Catalytic potential of carbon nanomaterials in peroxydisulfate (PDS) advanced oxidation systems for degradation of antibiotics remains poorly understood. This study revealed ordered mesoporous carbon (type CMK) acted as a superior catalyst for heterogeneous degradation of sulfadiazine (SDZ) in PDS system, with a first-order reaction kinetic constant (k) and total organic carbon (TOC) mineralization efficiency of 0.06 min?1 and 59.67% ± 3.4% within 60 min, respectively. CMK catalyzed PDS system exhibited high degradation efficiencies of five other sulfonamides and three other types of antibiotics, verifying the broad-degradation capacity of antibiotics. Under neutral pH conditions, the optimal catalytic parameters were an initial SDZ concentration of 44.0 mg/L, CMK dosage of 0.07 g/L, and PDS dosage of 5.44 mmol/L, respectively. X-ray photoelectron spectroscopy and Raman spectrum analysis confirmed that the defect structure at edge of CMK and oxygen-containing functional groups on surface of CMK were major active sites, contributing to the high catalytic activity. Free radical quenching analysis revealed that both SO4?? and ?OH were generated and participated in catalytic reaction. In addition, direct electron transfer by CMK to activate PDS also occurred, further promoting catalytic performance. Configuration of SDZ molecule was optimized using density functional theory, and the possible reaction sites in SDZ molecule were calculated using Fukui function. Combining ultra-high-performance liquid chromatography (UPLC)–mass spectrometry (MS)/MS analysis, three potential degradation pathways were proposed, including the direct removal of SO2 molecules, the 14S-17 N fracture, and the 19C-20 N and 19C-27 N cleavage of the SDZ molecule. The study demonstrated that ordered mesoporous carbon could work as a feasible catalytic material for PDS advanced oxidation during removal of antibiotics from wastewater.
- Cao, Di,Chen, Fan,Cheng, Hao,Huang, Cong,Li, Zhi-Ling,Liang, Bin,Nan, Jun,Sun, Kai,Wang, Ai-Jie
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supporting information
(2022/01/26)
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- Electrochemical Strategy for the Simultaneous Production of Cyclohexanone and Benzoquinone by the Reaction of Phenol and Water
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Cyclohexanone and benzoquinone are important chemicals in chemical and manufacturing industries. The simultaneous production of cyclohexanone and benzoquinone by the reaction of phenol and water is an ideal route for the economical production of the two c
- Wu, Ruizhi,Meng, Qinglei,Yan, Jiang,Liu, Huizhen,Zhu, Qinggong,Zheng, Lirong,Zhang, Jing,Han, Buxing
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p. 1556 - 1571
(2022/02/01)
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- Direct catalytic benzene hydroxylation under mild reaction conditions by using a monocationic μ-nitrido-bridged iron phthalocyanine dimer with 16 peripheral methyl groups
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Direct catalytic hydroxylation of benzene under mild reaction conditions proceeded efficiently in the presence of a monocationic μ-nitrido-bridged iron phthalocyanine dimer with 16 peripheral methyl groups in an acetonitrile solution with excess H2O2. Mechanistic studies suggested that the reaction was catalyzed by a high-valent iron-oxo species generated in situ. Moreover, the peripheral methyl groups of the catalyst were presumed to have enhanced the production rate of the iron-oxo species.
- Tanaka, Kentaro,Teoh, Chee-Ming,Toyoda, Yuka,Yamada, Yasuyuki
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supporting information
p. 955 - 958
(2022/02/07)
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- The effect of Br- and alkali in enhancing the oxidation of furfural to maleic acid with hydrogen peroxide
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This study was focused on investigating a novel catalytic system for the selective conversion of furfural to maleic acid (MA) in an aqueous system with hydrogen peroxide as an oxidant. A series of experiments that study the impacts of catalyst species, furfural concentration, catalyst dosage, reaction temperature, residue time, hydrogen peroxide concentration, excess water content, and solvent types on the oxidation of furfural to MA was carried out. The results showed that the co-existence of Br- and alkali sites might play a vital role in furfural oxidation, which could improve the MA yield remarkably. Under 90 °C for 3 h, 72.4 % MA yield was obtained with KOH and KBr as co-catalyst in an aqueous phase. Moreover, a possible reaction pathway of furfural oxidation was proposed on the basis of our reaction system.
- Yang, Tao,Li, Wenzhi,Ogunbiyi, Ajibola T.
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- Biosynthesis ofl-alanine fromcis-butenedioic anhydride catalyzed by a triple-enzyme cascadeviaa genetically modified strain
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In industry,l-alanine is biosynthesized using fermentation methods or catalyzed froml-aspartic acid by aspartate β-decarboxylase (ASD). In this study, a triple-enzyme system was developed to biosynthesizel-alanine fromcis-butenedioic anhydride, which was cost-efficient and could overcome the shortcomings of fermentation. Maleic acid formed bycis-butenedioic anhydride dissolving in water was transformed tol-alanineviafumaric acid andl-asparagic acid catalyzed by maleate isomerase (MaiA), aspartase (AspA) and ASD, respectively. The enzymatic properties of ASD from different origins were investigated and compared, as ASD was the key enzyme of the triple-enzyme cascade. Based on cofactor dependence and cooperation with the other two enzymes, a suitable ASD was chosen. Two of the three enzymes, MaiA and ASD, were recombinant enzymes cloned into a dual-promoter plasmid for overexpression; another enzyme, AspA, was the genomic enzyme of the host cell, in which AspA was enhanced by a T7promoter. Two fumarases in the host cell genome were deleted to improve the utilization of the intermediate fumaric acid. The conversion of whole-cell catalysis achieved 94.9% in 6 h, and the productivity given in our system was 28.2 g (L h)?1, which was higher than the productivity that had been reported. A catalysis-extraction circulation process for the synthesis ofl-alanine was established based on high-density fermentation, and the wastewater generated by this process was less than 34% of that by the fermentation process. Our results not only established a new green manufacturing process forl-alanine production fromcis-butenedioic anhydride but also provided a promising strategy that could consider both catalytic ability and cell growth burden for multi-enzyme cascade catalysis.
- Cui, Ruizhi,Liu, Zhongmei,Yu, Puyi,Zhou, Li,Zhou, Zhemin
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p. 7290 - 7298
(2021/09/28)
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- Effect of CTAB on the Oxidation of Furfural to Maleic Acid over Hierarchical CoAPO-5 Catalysts
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A series of hierarchical CoAPO-5 molecular sieves was hydrothermally prepared using cetyltrimethylammonium bromide (CTAB) as the template. The structural properties of CoAPO-5 molecular sieves with different amount of CTAB, including AFI-0.10, AFI-0.25, AFI-0.35, AFI-0.45 and AFI-0.55 were all characterized by XRD, SEM, N2 adsorption-desorption and NH3-TPD. The catalytic performance of as-prepared CoAPO-5 molecular sieves for the oxidation of furfural to maleic acid was evaluated. Research results indicated that the structure characteristics as well as the catalytic performances of CoAPO-5 molecular sieves were strongly influenced by CTAB concentration. Among those hierarchical CoAPO-5 catalysts, AFI-0.45 sample demonstrated highest maleic acid yield of 85.9% at 60℃ after 3 hr reaction. Also, the stability of AFI-0.45 was proved persistent for subsequent cycles.
- Zheng, Lijie,Sun, Xueni,Wang, Jun,Lu, Yang,Shao, Hui
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p. 237 - 244
(2021/04/09)
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- Metal Sub-nanoclusters Confined within Hierarchical Porous Carbons with High Oxidation Activity
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Metal sub-nanoclusters (SNCs) have shown great promise for a variety of catalytic reactions. However, the fabrication of stable metal SNCs simultaneously with high dispersion and high metal contents remains a challenge. Herein, we report a novel and versatile strategy for the synthesis of various bimetal SNCs stabilized within hierarchical porous carbons (HPC). This facile synthesis only involves the self-assembly of a metal-organic framework (MOF) as the precursor, a molten salt assisted pyrolysis process and the final metal replacement. The metal SNCs (mostly less than 0.8 nm) derived from the metal nodes of the MOF are exclusively confined and homogeneously dispersed throughout the organic ligands derived HPC at high loadings (up to 11.2 wt %). The obtained Cu-Pd@HPC composite exhibits superior catalytic activity and recycling durability in the selective transformation of furfural to maleic acid, achieving 97.8 % yield of maleic acid with a TOF value as high as 20.1 h?1 under mild conditions. DFT calculations reveal that the introduction of Pd shifts the partial density of states of Cu toward the Fermi level, leading to stronger chemisorption of furfural to enhance the catalytic activity.
- Zhao, Xin,Kong, Xiangpeng,Wang, Fengliang,Fang, Ruiqi,Li, Yingwei
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supporting information
p. 10842 - 10849
(2021/03/16)
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- Parahydrogen-Induced Polarization Relayed via Proton Exchange
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The hyperpolarization of nuclear spins is a game-changing technology that enables hitherto inaccessible applications for magnetic resonance in chemistry and biomedicine. Despite significant advances and discoveries in the past, however, the quest to establish efficient and effective hyperpolarization methods continues. Here, we describe a new method that combines the advantages of direct parahydrogenation, high polarization (P), fast reaction, and low cost with the broad applicability of polarization transfer via proton exchange. We identified the system propargyl alcohol + pH2 → allyl alcohol to yield 1H polarization in excess of P ≈ 13% by using only 50% enriched pH2 at a pressure of ≈1 bar. The polarization was then successfully relayed via proton exchange from allyl alcohol to various target molecules. The polarizations of water and alcohols (as target molecules) approached P ≈ 1% even at high molar concentrations of 100 mM. Lactate, glucose, and pyruvic acid were also polarized, but to a lesser extent. Several potential improvements of the methodology are discussed. Thus, the parahydrogen-induced hyperpolarization relayed via proton exchange (PHIP-X) is a promising approach to polarize numerous molecules which participate in proton exchange and support new applications for magnetic resonance.
- Them, Kolja,Ellermann, Frowin,Pravdivtsev, Andrey N.,Salnikov, Oleg G.,Skovpin, Ivan V.,Koptyug, Igor V.,Herges, Rainer,H?vener, Jan-Bernd
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supporting information
p. 13694 - 13700
(2021/09/07)
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- Method for preparing maleic acid by catalyzing cellulose with bifunctional solid catalyst
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The invention discloses a method for preparing maleic acid by catalyzing cellulose with a bifunctional solid catalyst, and belongs to the field of new energy and new materials. A heteropoly acid substituted salt composite catalyst has Lewis acidity, acidity and strong oxidizing property, can be respectively used as an acid catalyst and an oxidation catalyst, and is used for selectively catalyzing hydrolysis of cellulose, dehydration of glucose and oxidation of 5-hydroxymethylfurfural under a hydrothermal condition, so that higher maleic acid yield is realized. According to the method, the cellulose hydrolysis rate can reach 73.1%, the glucose conversion rate can reach 93.5%, the yield of 5-hydroxymethylfurfural can reach 85%, and the final yield of maleic acid can reach 44.2%. The process is easy and convenient to operate, low in cost and environmentally friendly, and a novel catalytic process can be provided for producing high-added-value bio-based chemicals through conversion of cellulose-based biomass.
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Paragraph 0018; 0021; 0022; 0024; 0025; 0027; 0028; 0030
(2021/05/29)
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- High-efficiency catalytic wet air oxidation of high salinity phenolic wastewater under atmospheric pressure in molten salt hydrate media
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An improved catalytic wet air oxidation (CWAO) process for high salinity phenolic wastewater is reported for the first time by using molten salt hydrates (MSHs) as reaction media. One feature of such a process is that it allows the operation to be conducted at atmospheric pressure owing to the temperature-increasing effect of MSHs. Another feature is that the inorganic salts in phenolic wastewater can be separated readily, taking advantage of the common-ion salting-out effect between inorganic salts and MSHs. Continuous catalytic oxidation degradation of the simulated high salinity phenolic wastewater demonstrated that more than 92% of phenol can be removed with chemical oxygen demand (COD) as high as 85% after reacting in CaCl2·3H2O medium at 150 °C with air as an oxidant. Meanwhile, the desalination efficiency of NaCl in continuous operation could reach up to 100%. It was found that CeCl3was an excellent catalyst for CWAO of phenol. XPS and UV-vis spectral characterization as well as radical scavenger experiments proved that [˙OH/Ce4+] was responsible for the synergistic catalytic degradation mechanism of phenol. Current work not only paves the way for developing a high-efficiency CWAO technology for concentrated organic wastewaters with high salinity, but also helps to better understand MSHs as reaction media.
- Tan, Hongzi,Wang, Shuai,Wang, Jinghua,Song, Feng,Sun, Xiuyu,Zhao, Rongrong,Zhang, Yuan,Cui, Hongyou
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supporting information
p. 2167 - 2174
(2021/02/06)
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- Enhanced nonradical catalytic oxidation by encapsulating cobalt into nitrogen doped graphene: highlight on interfacial interactions
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Supported metal catalysts are widely used for heterogeneous catalytic processes (e.g., Fenton-like reaction), but the mechanisms of interfacial processes are still ambiguous. Herein, unique nanocarbon based catalysts with Co nanoparticles encapsulated in
- Yu, Xiaoyong,Wang, Lijing,Wang, Xin,Liu, Hongzhi,Wang, Ziyuan,Huang, Yixuan,Shan, Guoqiang,Wang, Weichao,Zhu, Lingyan
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supporting information
p. 7198 - 7207
(2021/03/29)
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- Selective C?O Bond Cleavage of Bio-Based Organic Acids over Palladium Promoted MoOx/TiO2
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Hydrodeoxygenation chemistries play a key role in the upgrading of biomass-derived feedstocks. Among these, the removal of targeted hydroxyl groups through selective C?O bond cleavage from molecules containing multiple functionalities over heterogeneous catalysts has shown to be a challenge. Herein, we report a highly selective and stable heterogeneous catalyst for hydrodeoxygenation of tartaric acid to succinic acid. The catalyst consists of reduced Mo5+ centers promoted by palladium, which facilitate selective C?O bond cleavage, while leaving intact carboxylic acid end groups. Stable catalytic performance over multiple cycles is demonstrated. This catalytic system opens up opportunities for selective processing of biomass-derived sugar acids with a high degree of chemical functionality.
- Albarracín-Suazo, Sandra,Nacy, Ayad,Nikolla, Eranda,Pagán-Torres, Yomaira J.,Roberts, Charles A.,Ruiz-Valentín, Génesis,de Lima e Freitas, Lucas Freitas
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p. 1294 - 1298
(2020/12/29)
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- Hydroxyapatite-Supported Polyoxometalates for the Highly Selective Aerobic Oxidation of 5-Hydroxymethylfurfural or Glucose to 2,5-Diformylfuran under Atmospheric Pressure
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(NH4)5H6PV8Mo4O40 supported on hydroxyapatite (HAP) (PMo4V8/HAP (n)) was prepared through the ion exchange of hydroxy groups. This ion exchange favored the oxidative conversion of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF) in a one-pot cascade reaction with 96.0 % conversion and 83.8 % yield under 10 mL/min of O2 flow. PMo4V8/HAP (31) was used to explore the production of DFF directly from glucose with the highest yield of 47.9 % so far under atmospheric oxygen, whereas the yield of DFF increased to 54.7 % in a one-pot and two-step reaction. These results indicated that the active sites in PMo4V8/HAP (31) retained their activities without any interference toward one another, which enabled the production of DFF in a more cost-saving way by only using oxygen and one catalyst in a one-step reaction. Meanwhile, the rigid structure of HAP and strong interaction in PMo4V8/HAP (31) allowed this catalyst to be reused for at least six times with high stability and duration.
- Guan, Hongyu,Li, Ying,Wang, Qiwen,Wang, Xiaohong,Yu, Hang
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p. 997 - 1005
(2021/08/06)
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- Enhanced photocatalytic activity for 4-nitrophenol degradation using visible-light-driven In2S3/α-Fe2O3 composite
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In2S3/α-Fe2O3 composites were synthesized using the methods of hydrothermal treatment and reflux. Characterization such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Photoluminescence (PL) was used to characterize the crystallinity and morphology of the composites, which proved the successful synthesis of the In2S3/α-Fe2O3 heterostructures. The 4-nitrophenol (PNP) degradation experiments by visible light were studied to evaluate the photocatalytic activity of the In2S3/α-Fe2O3 composites. The composites showed much higher photocatalytic degradation activities and TOC removal rate than both pure In2S3 and α-Fe2O3. The PNP degradation rate of composites was about 4.7 and 11.9 times that of pure In2S3 and α-Fe2O3, respectively. The degradation process was detected by high performance liquid chromatography and mass spectrometry, and the degradation pathway was explained. Based on the trapping experiments, e? and ?OH were the main active species and a Z-scheme photocatalytic mechanism of In2S3/α-Fe2O3 was proposed, which showed the double advantage of high redox ability and efficient electron-hole pairs separation.
- Fang, Lujuan,Huang, Xiangyang,Jiang, Ruanjing,Liu, Zijing,Munthali, Rodger Millar,Wu, Xiaogang,Zhang, Ying
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- Heterogeneous Fenton-like oxidative degradation of sulfanilamide catalyzed by RuO2-rectorite composite
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RuO2-rectorite (RuO2-Rec) was prepared by intercalation, deposition and calcination. Its structure was characterized by XRD, XPS, SEM and EDS. It was used as a catalyst for the sulfanilamide (SA) degradation in the presence of H2O2. Unlike sodium-rectorite and RuO2 which couldn’t catalyze the degradation of SA, RuO2-Rec could effectively catalyze the decomposition of H2O2 into hydroxyl radicals to degrade SA. The degradation rate could reach ~ 100% under the optimal conditions of 58?μmol/L of SA, 1.16?mmol/L of H2O2, 0.133?g/L of RuO2-Rec, pH 3.5 and 25?°C in 5?h. The degradation process conformed to pseudo-first-order kinetic correlation. This degradation was affected by pH, the amount of RuO2-Rec and the concentrations of H2O2 and SA. However, under the optimal pH value of 3.5, a high degradation rate could be achieved with the increase in SA concentration from 58?μmol/L to 290?μmol/L as long as the optimal ratio of RuO2-Rec, H2O2 and SA kept unchanged. In addition, RuO2-Rec was stable and possessed low ruthenium leaching rate and excellent reusability. Therefore, RuO2-Rec is expected to be an active catalyst for the pollutant removal in the heterogeneous Fenton-like system.
- Pan, Feifei,Yang, Jianhong,Cai, Jun,Liu, Lianye
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p. 4595 - 4611
(2021/07/26)
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- Method of controlling scale in aqueous systems
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A method of inhibiting scale in an industrial water system includes the steps of dosing the industrial water system with a water treatment polymer comprising at least 10 mol % of carboxylic acid monomer and a quaternized naphthalimide fluorescent monomer as disclosed herein, and then monitoring the fluorescence of the water system. The polymers are also useful for flocculation and coagulation in wastewater treatment.
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- Oxidation of biomass-derived furans to maleic acid over nitrogen-doped carbon catalysts under acid-free conditions
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Maleic acid (MA) is a platform chemical used for synthesizing high-value polymers. Although MA can be produced from biomass-derived furfural, so far, only acidic catalysts have been proposed. Herein, for the first time, we report an acid-free furfural-to-MA conversion using nitrogen-doped carbon (NC) as an effective catalyst with the assistance of hydrogen peroxide (H2O2) as an oxidant. A high MA yield (61%) can be achieved over the NC-900 catalyst at 80 °C. The effects of reaction conditions, including H2O2 concentration, solvent type, reaction temperature, and time were systematically studied in detail and optimized. The ZIF-8-derived NC catalyst exhibited high activity owing to the existence of high graphitic nitrogen (N-Q) content in the carbon framework. The kinetics study indicates that the oxidation of furfural to MA over the NC-900 catalyst is via the formation of 5-hydroxy-furan-2(5H)-one as the main intermediate. Further, NC-900 can convert a variety of biomass-derived furan compounds to MA under acid-free conditions, indicating the versatility and applicability of the present acid-free, NC-based catalytic system.
- Ahamad, Tansir,Alshehri, Saad M.,Boo, Jing Rou,Liu, Chia-Hung,Matsagar, Babasaheb M.,Van Nguyen, Chi,Wu, Kevin C.-W.
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p. 1498 - 1506
(2020/03/23)
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- METHOD FOR PREPARING MALEIC ACID
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The present invention pertains to a method for the preparation of maleic acid from 5-hydroxy-2(5H)-furanone or a tautomer thereof, said method comprising the step of subjecting 5-hydroxy-2(5H)-furanone or a tautomer thereof to an oxidation reaction selected from the group consisting of enzymatic oxidation, and electrochemical oxidation; wherein said oxidation reaction is carried out at a pH of at least 2, preferably at a pH of at least 3.
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Page/Page column 21-22
(2021/01/22)
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- Carbon nanotubes as catalysts for wet peroxide oxidation: The effect of surface chemistry
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Three magnetic carbon nanotube (CNT) samples, named A30 (N-doped), E30 (undoped) and E10A20 (selectively N-doped), synthesized by catalytic chemical vapor deposition, were modified by introducing oxygenated surface groups (oxidation with HNO3, samples CNT-N), and by heat treatment at 800 °C for the removal of surface functionalities (samples CNT-HT). Both treatments lead to higher specific surface areas. The acid treatment results in more acidic surfaces, with higher amounts of oxygenated species being introduced on N-doped surfaces. Heat-treated samples are less hydrophilic than those treated with nitric acid, heat treatment leading to neutral or basic surfaces, only N-quaternary and N-pyridinic species being found by XPS on N-doped surfaces. These materials were tested in the catalytic wet peroxide oxidation (CWPO) of highly concentrated 4-nitrophenol solutions (4-NP, 5 g L?1) at atmospheric pressure, T = 50 °C and pH = 3, using a catalyst load of 2.5 g L?1 and the stoichiometric amount of H2O2 needed for the complete mineralization of 4-NP. The high temperature treatment enhanced significantly the activity of the CNTs towards CWPO, evaluated in terms of 4-NP and total organic carbon conversion, due to the increased hydrophobicity of their surface. In particular, E30HT and E10A20HT were able to remove ca. 100% of 4-NP after 8 h of operation. On the other hand, by treating the CNTs with HNO3, the activity of the less hydrophilic samples decreased upon increasing the concentration of surface oxygen-containing functionalities, whilst the reactivity generated inside the opened nanotubes improved the activity of the highly hydrophilic A30 N.
- Martin-Martinez, Maria,Machado, Bruno F.,Serp, Philippe,Morales-Torres, Sergio,Silva, Adrián M.T.,Figueiredo, José L.,Faria, Joaquim L.,Gomes, Helder T.
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p. 332 - 340
(2019/03/17)
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- One-Pot Synthesis of Renewable Phthalic Anhydride from 5-Hydroxymethfurfural by using MoO3/Cu(NO3)2 as Catalyst
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Herein, a synthetic pathway to renewable phthalic anhydride (PA) from 5-hydroxymethfurfural (HMF) in one pot is reported. The commonly available catalysts MoO3 and Cu(NO3)2 play a crucial role in integrating the multiple steps of the reaction, namely decarbonylation of HMF to active furyl intermediate (AFI), oxidation of HMF to maleic anhydride (MA), Diels–Alder cycloaddition of AFI and MA, and subsequent dehydration, in one pot. Under mild reaction conditions, a 63.2 % yield of PA is obtained from HMF. Compared with the currently reported route to renewable PA based on the Diels–Alder cycloaddition of biomass-derived MA and furan, this convenient one-pot synthesis represents a great improvement in efficiency.
- Jia, Wenlong,Sun, Yong,Zuo, Miao,Feng, Yunchao,Tang, Xing,Zeng, Xianhai,Lin, Lu
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p. 640 - 646
(2020/01/22)
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- Study of the Oxidative Cleavage Proposed in the Biogenesis of Transtaganolides/Basiliolides: Pyran-2-one Aromaticity-Mediated Regioselective Control and Biogenetic Implications
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The synthetic feasibility of the oxidative cleavage: epoxidation of 7-O-geranylscopoletin followed by electrocyclic ring-opening, proposed in the biogenesis of transtaganolides/basiliolides is studied. Unlike the proposed pericyclic reactions, this pathway has not yet been addressed. Three synthetic strategies have been tested consisting of: i) Baeyer–Villiger oxidation of p-quinoids, ii) hydrolysis of quinone monoketals, or iii) direct fragmentation by using oxygen donors. Oxidation of the benzene ring of hydroxylated coumarins has been achieved using peroxyacids, but cleavage took place between undesired positions. The aromaticity conservation of the pyran-2-one cycle during oxidation is the controlling factor of these observed regioselectivities. The use of a 4,5-dihydroxy-2-methoxycinnamate model, in which the pyran-2-one ring does not exert influence on oxidation, has allowed the design of a synthetic sequence toward an analogue of the natural pyran-2-one isolated from Thapsia transtagana, key in the biogenesis. Mechanistic proposals for the obtained results as well as their biogenetic implications are raised.
- álvarez, José María,Jorge, Zacarías D.,Massanet, Guillermo M.
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supporting information
(2020/03/05)
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- Directly Microwave-Accelerated Cleavage of C?C and C?O Bonds of Lignin by Copper Oxide and H2O2
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Model erythro, phenolic, and nonphenolic lignin β-O-4 dimer compounds are treated with copper oxide and H2O2 at the electronic field maximum position of a single-mode 2.45 GHz microwave system equipped with a cavity resonator. The products obtained through microwave heating and oil-bath heating with the same reaction vessel and temperature profile are quantitatively compared. Dimer degradation is found to proceed through consecutive elementary reactions. The phenolic dimer is dehydroxylated and this is followed by the spontaneous cleavage of Cα?Cβ and C?O?C bonds to produce guaiacol, vanillin, and vanillic acid. The reaction of the nonphenolic dimer produces veratric acid, veratraldehyde, and guaiacol. Microwave irradiation accelerates cleavage of the side chain and the oxidation of vanillin to vanillic acid. However, no acceleration of veratraldehyde oxidation to veratric acid or aromatic ring cleavage to produce dicarboxylic acids is observed. The selective acceleration of elementary reactions during the degradation of model lignin compounds indicates that microwaves interact with reaction intermediates that are sensitive to electromagnetic waves.
- Qu, Chen,Ito, Keigo,Katsuyama, Isamu,Mitani, Tomohiko,Kashimura, Keiichiro,Watanabe, Takashi
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p. 4510 - 4518
(2020/05/18)
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- A cobalt-substituted Keggin-Type polyoxometalate for catalysis of oxidative aromatic cracking reactions in water
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Efficient detoxification of harmful benzene rings into useful carboxylic acids in water is indispensable for achieving a clean water environment. We report herein that oxidative aromatic cracking (OAC) reactions in water were achieved using a catalytic system with a cobalt-substituted Keggin-Type polyoxometalate (Co-POM) as a catalyst, an Oxone monopersulfate compound as a sacrificial oxidant and sodium bicarbonate as an additive under mild conditions. Sodium bicarbonate plays a crucial role in the selective OAC reactions by Co-POM using ethylbenzenesulfonate as a model substrate. The reactive species was characterized to be a cobalt(iii)-oxyl species based on 31P NMR, UV-vis spectroscopic, kinetic, and theoretical analyses. The electrophilicity of the cobalt(iii)-oxyl species was demonstrated by a linear relationship with a negative slope in the Hammett plots of initial rates obtained from the OAC reactions of m-xylenesulfonate derivatives. Besides, we have verified the degradation pathway of the OAC reactions using benzene as a model substrate in the catalytic system. The degradation was initiated by an electrophilic attack of the cobalt(iii)-oxyl species on benzene to yield phenol followed by producing catechol, muconic acid, maleic/fumaric acid, tartaric acid derivatives and formic acid on the basis of 1H NMR spectroscopic analysis.
- Hong, Dachao,Kitagawa, Yasutaka,Kon, Yoshihiro,Shimoyama, Yoshihiro,Tamura, Satoru
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p. 8042 - 8048
(2020/12/28)
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- ELECTROCHEMICAL OXIDATION OF AROMATIC ALDEHYDES IN ACIDIC MEDIA
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Methods for electrochemically oxidizing aromatic aldehydes, such as furfural and furfural derivatives, to carboxylic acids in acidic solutions are provided. Also provided are electrochemical cells for carrying out the oxidation reactions. The electrochemical oxidations may be conducted in aqueous media at ambient pressure and mild temperatures.
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Paragraph 0044-0045
(2019/05/02)
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- Reactivity control of a photocatalytic system by changing the light intensity
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We report a novel light-intensity dependent reactivity approach allowing us to selectively switch between triplet energy transfer and electron transfer reactions, or to regulate the redox potential available for challenging reductions. Simply by adjusting the light power density with an inexpensive lens while keeping all other parameters constant, we achieved control over one- and two-photon mechanisms, and successfully exploited our approach for lab-scale photoreactions using three substrate classes with excellent selectivities and good product yields. Specifically, our proof-of-concept study demonstrates that the irradiation intensity can be used to control (i) the available photoredox reactivity for reductive dehalogenations to selectively target either bromo- or chloro-substituted arenes, (ii) the photochemical cis-trans isomerization of olefins versus their photoreduction, and (iii) the competition between hydrogen atom abstraction and radical dimerization processes.
- Kerzig, Christoph,Wenger, Oliver S.
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p. 11023 - 11029
(2019/12/28)
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- The impact of an isoreticular expansion strategy on the performance of iodine catalysts supported in multivariate zirconium and aluminum metal-organic frameworks
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Iodine functionalized variants of DUT-5 (Al) and UiO-67 (Zr) were prepared as expanded-pore analogues of MIL-53 (Al) and UiO-67 (Zr). They were prepared using a combination of multivariate and isorecticular expansion strategies. Multivariate MOFs with a 25% iodine-containing linker was chosen to achieve an ideal balance between a high density of catalytic sites and sufficient space for efficient diffusion. Changes to the oxidation potential of the catalyst as a result of the pore-expansion strategy led to a decrease in activity with electron rich substrates. On the other hand, these larger frameworks proved to be more efficient catalysts for substrates with higher oxidation potentials. Recyclability tests for these larger MOFs showed sustained catalytic activity over multiple recycles.
- Tahmouresilerd, Babak,Moody, Michael,Agogo, Louis,Cozzolino, Anthony F.
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supporting information
p. 6445 - 6454
(2019/05/24)
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- Template free mild hydrothermal synthesis of core-shell Cu2O(Cu)?CuO visible light photocatalysts for N-acetyl-para-aminophenol degradation
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Solar photocatalytic processes are a promising approach to environmental remediation, however their implementation requires improvements in visible light harvesting and conversion and a focus on low cost, Earth abundant materials. Semiconducting copper oxides are promising visible light photocatalysts for solar fuels and wastewater depollution. Here we report the mild, hydrothermal (template-free) synthesis of core-shell Cu2O(Cu)?CuO photocatalytic architectures for the visible light photocatalytic degradation of N-acetyl-para-aminophenol (APAP). Hollow and rattle-like core-shell nanosphere aggregates with diameters between 200 nm and 2.5 μm formed under different synthesis conditions; all comprised an inner Cu2O shell, formed of 10-50 nm nanoparticles, surrounded by a protective corona of CuO nanoparticles. High reductant and structure-directing agent concentrations promoted the formation of a yolk-like Cu2O/Cu core, associated with improved photophysical properties, notably a high oxidation potential and suppressed charge carrier recombination, that correlated with the highest apparent quantum efficiency (8%) and rate of APAP removal (7 μmol g-1 min-1). Trapping experiments demonstrated hydroxyl radicals were the primary active species responsible for APAP oxidation to quinones and short chain carboxylic acids. Rattle-like core-shell Cu2O/Cu?CuO nanospheres exhibited excellent physiochemical stability and recyclability for APAP photocatalytic degradation.
- Karthikeyan, Sekar,Chuaicham, Chitiphon,Pawar, Radheshyam R.,Sasaki, Keiko,Li, Wei,Lee, Adam F.,Wilson, Karen
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supporting information
p. 20767 - 20777
(2019/09/30)
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- Iron-based metalloporphyrins as efficient catalysts for aerobic oxidation of biomass derived furfural into maleic acid
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A series of porphyrin type catalysts with the metal active sites of Fe were prepared and investigated in aerobic oxidation of biomass-based furfural to maleic acid (MAD) in aqueous phase. The catalytic performance of meso-tetrakis(4-bromophenyl)porphyrin iron (III) chloride (FeT(p-Br)PPCl) immobilized on different supports was evaluated. It was interesting to find that the catalytic activity varied with the supports and followed the trend: FeT(p-Br)PPCl/SBA–15 > FeT(p-Br)PPCl/meso-ZSM–5 > FeT(p-Br)PPCl/MCM-41. The effect of reaction conditions were discussed in detail over FeT(p-Br)PPCl/SBA-15 catalyst, and 56.1% yield and 73.8% selectivity of MAD were obtained from renewable furfural under the optimal conditions. Moreover, the FeT(p-Br)PPCl/SBA-15 catalyst could be reused five times without a significant decrease of activity in recycling examinations.
- Xie, Yongdi,Huang, Yi,Wu, Chunyan,Yuan, Wenwen,Xia, Yongmei,Liu, Xiang,Wang, Haijun
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- Rearrangements and Tautomeric Transformations of Heterocyclic Compounds in Homogeneous Reaction Systems Furfural–Н2О2–Solvent
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General information on the reactions of furfurals with hydrogen peroxide is given. We have discussed the Baeyer–Villiger rearrangement of furan 2-hydroxyhydroperoxides and tautomeric transformations with proton transfer of 2-hydroxyfuran and β-formylacrylic acid formed in a homogeneous reaction system furfural–Н2О2–solvent under the catalysis with the formed acids. The factors affecting these rearrangements and tautomeric transformations as well as their specificity in comparison with benzene type compounds, and the pathway of the reactions of furan aldehydes with Н2О2 in water have been analyzed. Ketoenol tautomerism of cyclic hemiacetal form of β-formylacrylic acid leading to its transformation into succinic anhydride has been described for the first time.
- Badovskaya,Poskonin
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p. 1568 - 1579
(2018/11/10)
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- Fabrication of a novel PbO2 electrode with a graphene nanosheet interlayer for electrochemical oxidation of 2-chlorophenol
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A novel PbO2 electrode with a graphene nanosheet interlayer (marked as GNS-PbO2) was prepared combining electrophoretic deposition and electro-deposition technologies. The micro morphology, crystal structure and surface chemical states of GNS-PbO2 electrodes were characterized using scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Their electrochemical properties and stability were determined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ·OH radicals test and accelerated life test, and compared with traditional PbO2 electrodes. Besides, their potential application in the electrochemical degradation of 2-chlorophenol (2-CP) was investigated. The GNS-PbO2 electrode possessed perfect octahedral β-PbO2 microcrystals, and its grain size was much smaller than that of traditional PbO2 electrode. It exhibited higher electrochemical activity than traditional PbO2 electrode due to its larger electrochemical active surface area and stronger ·OH radicals generation ability. The service lifetime of GNS-PbO2 electrode (107.9?h) was 1.93 times longer than that of traditional PbO2 electrode (55.9?h). The electrochemical degradation rate constant of 2-CP on GNS-PbO2 electrode (kapp?=?2.75?×?10?2?min?1) is much higher than for PbO2 electrode (kapp?=?1.76?×?10?2?min?1). 2-CP oxidation yielded intermediates including aromatic compounds (catechol, phenol and ortho-benzoquinone) and organic acids (oxalic acid, maleic acid and glutaconic acid), and a possible degradation pathway for 2-CP was proposed accordingly.
- Duan, Xiaoyue,Zhao, Cuimei,Liu, Wei,Zhao, Xuesong,Chang, Limin
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p. 424 - 436
(2017/04/28)
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- Porous Zirconium–Furandicarboxylate Microspheres for Efficient Redox Conversion of Biofuranics
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Biofuranic compounds, typically derived from C5 and C6 carbohydrates, have been extensively studied as promising alternatives to chemicals based on fossil resources. The present work reports the simple assembly of biobased 2,5-furandicarboxylic acid (FDCA) with different metal ions to prepare a range of metal–FDCA hybrids under hydrothermal conditions. The hybrid materials were demonstrated to have porous structure and acid–base bifunctionality. Zr-FDCA-T, in particular, showed a microspheric structure, high thermostability (ca. 400 °C), average pore diameters of approximately 4.7 nm, large density, moderate strength of Lewis-base/acid centers (ca. 1.4 mmol g?1), and a small number of Br?nsted-acid sites. This material afforded almost quantitative yields of biofuranic alcohols from the corresponding aldehydes under mild conditions through catalytic transfer hydrogenation (CTH). Isotopic 1H NMR spectroscopy and kinetic studies verified that direct hydride transfer was the dominant pathway and rate-determining step of the CTH. Importantly, the Zr-FDCA-T microspheres could be recycled with no decrease in catalytic performance and little leaching of active sites. Moreover, good yields of C5 (i.e., furfural) or C4 products [i.e., maleic acid and 2(5H)-furanone] could be obtained from furfuryl alcohol without oxidation of the furan ring over these metal–FDCA hybrids. The content and ratio of Lewis-acid/base sites were demonstrated to dominantly affect the catalytic performance of these redox reactions.
- Li, Hu,Liu, Xiaofang,Yang, Tingting,Zhao, Wenfeng,Saravanamurugan, Shunmugavel,Yang, Song
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p. 1761 - 1770
(2017/04/27)
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- PROCESS OF PREPARING IMINODISUCCINIC ACID AND COMPOSITION THEREOF
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The present disclosure provides a process for preparing iminodisuccinic acid salts using maleic anhydride, aspartic acid, and a base in water. In an example, maleic anhydride and aspartic acid are mixed with a base to form a slurry, preferably having a viscosity of about 1,000 cps or less. Preferably, the pH is raised to about 10 or above to achieve a homogenous clear solution. Water is distilled out increase the concentration of reactants. The solution is then heated to reflux, and the reaction allowed to proceed for a pre- determined time period. The present disclosure also provides a composition comprising about 35 wt% or less maleic anhydride, about 35 wt% or less aspartic acid, water, and a base, wherein said composition has a temperature of about 80°C or less, a pH of about 10 or greater and a viscosity of about 10000 cps or less.
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Page/Page column 9
(2016/11/28)
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- Selective aerobic oxidation of furfural to maleic anhydride with heterogeneous Mo-V-O catalysts
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A heterogeneous catalytic system using binary Mo-V metal oxides as catalysts was demonstrated for the selective aerobic oxidation of furfural to maleic anhydride (MA). Aspects such as the solvent for the reaction, the phase composition and the Mo/V ratio for the catalyst, and other reaction conditions were investigated in detail. Up to 65% yield of MA was achieved over the Mo4VO14 catalyst in an acetic acid solvent under optimal conditions. The catalyst could be recycled. The reaction mechanism and the role of the acetic acid solvent were also discussed.
- Li, Xiukai,Ho, Ben,Zhang, Yugen
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supporting information
p. 2976 - 2980
(2016/06/06)
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- Vanadium-oxo immobilized onto Schiff base modified graphene oxide for efficient catalytic oxidation of 5-hydroxymethylfurfural and furfural into maleic anhydride
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Graphene oxide (GO) sheets are emerging as a new class of carbocatalyst, and also a perfect platform for molecular engineering. The hydroxyl groups on either side of GO sheets can function as anchors by employing them as scaffolds linking organometallic nodes and vanadium-oxo was homogeneously immobilized on a Schiff base modified GO support via covalent bonding. The developed VO-NH2-GO was shown to be an efficient and recyclable heterogeneous catalyst for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) into maleic anhydride. Up to 95.3% yield of maleic anhydride from HMF and 62.4% from furfural were achieved under optimized reaction conditions. The immobilized vanadium oxo was identified as the active sites, while the residual oxygen-containing groups worked synergistically to adsorb HMF to maintain a high reactant concentration around the catalyst. The STY value was enhanced significantly over VO-NH2-GO, compared with homogeneous or heterogeneous traditional supported V based catalyst.
- Lv, Guangqiang,Chen, Chunyan,Lu, Boqiong,Li, Jinlong,Yang, Yongxing,Chen, Chengmeng,Deng, Tiansheng,Zhu, Yulei,Hou, Xianglin
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p. 101277 - 101282
(2016/11/11)
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- Synthesis of highly selective nano-structured functionalized SBA-15 metformin palladium composite catalyst in partial hydrogenation of alkynes
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In this research, a heterogeneous Nano-Structured functionalized SBA-15 metformin palladium composite catalyst is reported for the selective hydrogenation of alkynes. In the first place, A series of the heterogeneous mesoporous SBA-15 metformin palladium catalyst were prepared and afterwards the condition and the ratio of used materials were optimized to give rise a suitable high performance catalyst. The final nano-structured catalyst was characterized by X-ray powder diffraction, BET surface area, FT-IR spectrophotometer, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) and served in partial hydrogenation of different alkynes, with high selectivity and high yield. The liquid phase hydrogenation was conducted under mild condition of room temperature and atmospheric pressure. The reactions were monitored every half an hour by gas chromatography and all of them were completed during 4-6 hours. The products were characterized by 1H-NMR, 13C-NMR, FT-IR, and Mass Spectrometry (MS) that strongly confirmed the (Z)-double bond configuration of produced alkenes. This prepared catalyst is competitive with the best palladium catalysts known for the selective liquid phase hydrogenation of alkynes and can be easily recovered and regenerated with keeping high activity and selectivity over multiple cycles with a simple regeneration procedure.
- Kojoori, Reza Kia
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p. 3144 - 3149
(2016/11/18)
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