- Gas Evolution Oscillators. 2. A Reexamination of Formic Acid Dehydration
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At formic acid concentrations of about 0.3 M in warm concentrated sulfuric acid, carbon monoxide is evolved smoothly whether the solution is stirred or not.If such a solution is rapidly stirred, decay of formic acid obeys clean irreversible first-order kinetics.If the solution is not stirred, the concentration of dissolved carbon monoxide rises to a limit of about 0.07 M; this value is about 80 times the equilibrium solubility at 1 atm.In an unstirred solution, the system approaches a "pseudoequilibrium" in which the concentrations of dissolved HCOOH and CO are about equal.If the concentration of formic acid is increased to about 4 M, gas is evolved from a gently stirred solution in oscillatory pulses.The amount of gas evolved during a pulse decreases with successive pulses, the maximum change in dissolved-gas concentration being approximately 0.07 M per pulse.These observations indicate that the oscillations result from repetitive release of supersaturation by homogeneous nucleation; they invalidate the purely chemical explanation developed by Showalter and Noyes.Supersaturations of up to 80-fold suggest that formic acid in concentrated sulfuric acid can generate carbon monoxide in situ at concentrations that could otherwise only be attained with high-pressure apparatus.
- Smith, Kenneth W.,Noyes, Richard M.,Bowers, Peter G.
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Read Online
- Glycolic acid production using ethylene glycol-oxidizing microorganisms
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Screening for microorganisms oxidizing ethylene glycol to glycolic acid was carried out. Among stock cultures, several yeasts and acetic acid bacteria showed high glycolic acid producing activity. Pichia naganishii AKU 4267 formed the highest concentration of glycolic acid, 35.3 g/l, from 10% (v/v) ethylene glycol (molar conversion yield, 26.0%). Among soil isolates, Rhodotorula sp. 3Pr-126, isolated using propylene glycol as a sole carbon source, formed the highest concentration of glycolic acid, 25.1 g/l, from 10% (v/v) ethylene glycol (molar conversion yield, 18.5%). Rhodotorula sp. 3Pr-126 showed higher activity toward 20% (v/v) ethylene glycol than P. naganishii AKU 4267. Optimization of the conditions for glycolic acid production was investigated using P. naganishii AKU 4267 and Rhodotorula sp. 3Pr-126. Under the optimized conditions, P. naganishii AKU 4267 and Rhodotorula sp. 3Pr-126 formed 105 and 110 g/l of glycolic acid (corrected molar conversion yields, 88.0 and 92.2%) during 120 h of reaction, respectively.
- Kataoka, Michihiko,Sasaki, Mie,Hidalgo, Aklani-Rose G.D.,Nakano, Michiko,Shimizu, Sakayu
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Read Online
- Theoretical study of Al(iii)-catalyzed conversion of glyoxal to glycolic acid: Dual activated 1,2-hydride shift mechanism by protonated Al(OH) 3 species
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Density functional theory calculations demonstrate that Al(iii)-catalyzed conversion of glyoxal to glycolic acid proceeds via a 7-membered dual Lewis acid-hydrogen bonding activation transition state of the 1,2-hydride shift, rather than the previously proposed 5-membered metal-alkoxide chelate activation transition state. The Royal Society of Chemistry 2009.
- Ohshima, Takashi,Yamamoto, Yoshihiro,Takaki, Usaji,Inoue, Yoshihisa,Saeki, Takuya,Itou, Kenji,Maegawa, Yusuke,Iwasaki, Takanori,Mashima, Kazushi
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Read Online
- Facilitated series electrochemical hydrogenation of oxalic acid to glycolic acid using TiO2 nanotubes
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In this study, the electrochemical reduction of oxalic acid (OX) was performed at electrodes made of TiO2 nanotubes (TNTs) in an aqueous medium under potentiostatic control in a two-compartment cell. The competing H2 evolution was almost non-existent at an applied potential of ?1.0 V vs Ag/AgCl. Thus, complete conversion of OX was achieved in high chemical (95%) and Faradaic (67%) yields. The selectivity of glycolic acid (GC) formation over that of glyoxylic acid (GO) is controlled by the length of the TNTs. A high selectivity (GC/GO ≈ 10) was obtained (glycolic acid/glyoxylic acid ≈ 10). The physical properties of the TNTs, such as length, uniformity, and mechanical strength, were controlled by varying the anodization time and the electrolyte composition.
- Im, Sunmi,Park, Yiseul,Saad, Sarwar
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- PROCESSES FOR PREPARING ALDARIC, ALDONIC, AND URONIC ACIDS
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Various processes for preparing aldaric acids, aldonic acids, uronic acids, and/or lactone(s) thereof are described. For example, processes for preparing a C2-C7 aldaric acid and/or lactone(s) thereof by the catalytic oxidation of a C2-C7 aldonic acid and/or lactone(s) thereof and/or a C2-C7 aldose are described.
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Paragraph 0113-0116
(2021/05/29)
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- Experimental and kinetic study of the conversion of waste starch into glycolic acid over phosphomolybdic acid
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The starch used to enhance the paper surface dissolves in water during the production process and forms pollutants that accumulate in water when old corrugated cardboard (OCC) is returned to a paper mill for pulping and reuse. At present, anaerobic fermentation is widely used in the paper industry to treat starch-containing wastewater, producing biogas energy, or oxidative decomposition, which is a huge waste of valuable starch resources. Phosphomolybdic acid (PMo12) is a highly selective catalyst for the oxidation of carbohydrates; therefore, PMo12 can be envisaged as a suitable catalyst to convert waste starch into glycolic acid, an important high added-value chemical. In this paper, the catalytic oxidation technology of PMo12 was explored to produce glycolic acid from starch contained in OCC papermaking wastewater, and the kinetics and influencing factors of the catalytic oxidation reaction were studied. The results indicated that the PMo12-catalyzed oxidation of starch followed a first-order reaction; the reaction rate constant increased with increasing the temperature, the apparent activation energy of starch to monosaccharide was 104.7 kJ mol-1, the apparent activation energies of starch and monosaccharide to humins were 126.5 and 140.5 kJ mol-1, and the apparent activation energy of monosaccharide to glycolic acid was 117.2 kJ mol-1. The yields of monosaccharide and glycolic acid were 80.7 wt% and 12.9 wt%, respectively, and the utilization of starch resources was about 90.0 wt% under the following reaction conditions: temperature, 145 °C; reaction time, 120 min; pH, 2. Therefore, the feasibility of the PMo12-catalyzed oxidation of starch to produce high value-added glycolic acid is demonstrated, which has theoretical guiding significance and potential application value for the clean production and resource utilization of waste starch in the OCC papermaking process.
- Dai, Hongqi,Qiao, Yongzhen,Wang, Xiu
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p. 30961 - 30970
(2021/11/19)
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- Homogeneous Reforming of Aqueous Ethylene Glycol to Glycolic Acid and Pure Hydrogen Catalyzed by Pincer-Ruthenium Complexes Capable of Metal–Ligand Cooperation
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Glycolic acid is a useful and important α-hydroxy acid that has broad applications. Herein, the homogeneous ruthenium catalyzed reforming of aqueous ethylene glycol to generate glycolic acid as well as pure hydrogen gas, without concomitant CO2 emission, is reported. This approach provides a clean and sustainable direction to glycolic acid and hydrogen, based on inexpensive, readily available, and renewable ethylene glycol using 0.5 mol % of catalyst. In-depth mechanistic experimental and computational studies highlight key aspects of the PNNH-ligand framework involved in this transformation.
- Zou, You-Quan,von Wolff, Niklas,Rauch, Michael,Feller, Moran,Zhou, Quan-Quan,Anaby, Aviel,Diskin-Posner, Yael,Shimon, Linda J. W.,Avram, Liat,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 4715 - 4722
(2021/02/20)
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- The selective oxidation of glycerol over metal-free photocatalysts: insights into the solvent effect on catalytic efficiency and product distribution
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Selective oxidation of glycerol to high value-added derivatives is a promising biomass conversion pathway, but the related reaction mechanism, in particular the solvent effect, is rarely studied. In this work, O-doped g-C3N4was used as a metal-free catalyst to catalyze the selective oxidation of glycerol in different solvents. It was found that solvents can affect both catalytic efficiency and product distribution. A series of controlled experiments and theoretical calculation were applied to attest that the difference in interaction between glycerol and catalysts in different solvents is the main factor: competitive adsorption and hydrogen bond network from water inhibit the adsorption and activation of glycerol on the catalyst surface and reduce the conversion efficiency, while in acetonitrile, the stronger adsorption makes the oxidation reaction continue to yield esters. Two reaction routes in different solvents over O-doped g-C3N4are proposed for the first time, which is helpful for people to better understand the related reaction mechanism.
- Fan, Mingming,Haryonob, Agus,Jiang, Pingping,Leng, Yan,Yue, Chengguang,Zhang, Pingbo
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p. 3385 - 3392
(2021/06/06)
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- Oxidative Conversion of Glucose to Formic Acid as a Renewable Hydrogen Source Using an Abundant Solid Base Catalyst
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Formic acid is one of the most desirable liquid hydrogen carriers. The selective production of formic acid from monosaccharides in water under mild reaction conditions using solid catalysts was investigated. Calcium oxide, an abundant solid base catalyst available from seashell or limestone by thermal decomposition, was found to be the most active of the simple oxides tested, with formic acid yields of 50 % and 66 % from glucose and xylose, respectively, in 1.4 % H2O2 aqueous solution at 343 K for 30 min. The main reaction pathway is a sequential formation of formic acid from glucose by C?C bond cleavage involving aldehyde groups in the acyclic form. The reaction also involves base-catalyzed aldose-ketose isomerization and retroaldol reaction, resulting in the formation of fructose and trioses including glyceraldehyde and dihydroxyacetone. These intermediates were further decomposed into formic acid or glycolic acid. The catalytic activity remained unchanged for further reuse by a simple post-calcination.
- Takagaki, Atsushi,Obata, Wataru,Ishihara, Tatsumi
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p. 954 - 959
(2021/07/14)
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- Electro-oxidation of glycerol into formic acid by nickel-copper electrocatalysts
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Herein, non-precious metallic nickel-copper electrocatalysts were synthesized for electro-oxidation of glycerol in alkaline electrolytes. Activated carbon felt (ACF) is used as a supporting material because of its good conductivity, chemical inertness, and porous structure which is conducive to the transport of the reactants/electrons. The structural features of the catalysts were characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical activity of the catalysts was revealed by cyclic voltammetry, linear sweeping voltammetry, and chronoamperometry. The electrochemical results show that the Cu1Ni1@ACF catalyst possesses the highest current density of 1.31 mA cm-2 at 1.895 V. High-performance liquid chromatography results show that the as-prepared catalysts have high selectivities for formic acid (FA). Especially, the Cu1Ni1@ACF catalyst yields a selectivity of 97.4% for FA, which has so far been the largest value reported in the literature. Additionally, the effects of applied potentials and reaction time on product selectivity were studied.
- Shen, Yi,Zhang, Jiali
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- Method for synergistically preparing formic acid and glycollic acid by catalyzing 1, 3-dihydroxyacetone with bimetallic catalyst
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The invention discloses a method for synergistically preparing formic acid and glycollic acid by catalyzing 1, 3-dihydroxyacetone with a bimetallic catalyst, and belongs to the technical field of chemical synthesis and biomass heterogeneous catalytic conversion. The preparation method comprises the following specific steps: putting a bimetallic catalyst, 1, 3-dihydroxyacetone and a solvent into a reaction container, finally adding an oxidant, sealing the reaction container, and starting a reaction to prepare formic acid and glycollic acid compounds, wherein the initial concentration of 1, 3-dihydroxyacetone is not lower than 0.1 mol/L, the initial reaction pH is 0.5-9, the reaction temperature is 20-100 DEG C, and the reaction time is 1-72 hours. According to the invention, the efficient synergistic production of formic acid and glycollic acid can be realized, wherein the yield of formic acid is 91.06%, the yield of glycollic acid is 82.46%, the utilization rate of carbon atoms is 85.33%, and the carbon atom utilization rate is extremely high; and the method has the advantages of mild reaction conditions, no alkali, cheap catalyst, simple preparation and wide application prospect.
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Paragraph 0043-0053
(2021/05/29)
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- Ambient base-free glycerol oxidation over bimetallic PdFe/SiO2 by in situ generated active oxygen species
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Low temperature oxidation of alcohols over heterogeneous catalysts is exceptionally challenging, particularly under neutral conditions. Herein, we report on an efficient, base-free method to oxidise glycerol over a 0.5%Pd-0.5%Fe/SiO2 catalyst at ambient temperature in the presence of gaseous H2 and O2. The exceptional catalytic performance was attributed to the in situ formation of highly reactive surface-bound oxygenated species, which promote the dehydrogenation on the alcohol. The PdFe bimetallic catalyst was determined to be significantly more active than corresponding monometallic analogues, highlighting the important role both metals have in this oxidative transformation. Fe leaching was confirmed to occur over the course of the reaction but sequestering experiments, involving the addition of bare carbon to the reactions, confirmed that the reaction was predominantly heterogeneous in nature. Investigations with electron paramagnetic resonance spectroscopy suggested that the reactivity in the early stages was mediated by surface-bound reactive oxygen species; no homogeneous radical species were observed in solution. This theory was further evidenced by a direct H2O2 synthesis study, which confirmed that the presence of Fe in the bimetallic catalyst neither improved the synthesis of H2O2 nor promoted its decomposition over the PdFe/SiO2 catalyst.
- Underhill, Ricci,Douthwaite, Mark,Lewis, Richard J.,Miedziak, Peter J.,Armstrong, Robert D.,Morgan, David J.,Freakley, Simon J.,Davies, Thomas,Folli, Andrea,Murphy, Damien M.,He, Qian,Akdim, Ouardia,Edwards, Jennifer K.,Hutchings, Graham J.
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p. 303 - 324
(2021/01/07)
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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 oxidation of glycerol over different shaped WO3 supported Pt NPs
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In this work, different shaped WO3 (rod-like, lamellar and cuboid) supported Pt catalysts were prepared in a facile routine and tested in the selective oxidation of glycerol in base-free aqueous solution. Characterizations indicated that rod-like WO3 supported Pt catalyst (Pt/R-WO3) possesses higher surface area because of the formation of vertical pore channels and highly exposed plane (100), the deposited Pt atoms combined strongly with the terminal [sbnd]W[dbnd]O in rod-like WO3. These properties promoted the adsorption, storage and surface diffusion of oxygen over Pt/R-WO3 which exhibited the excellent activity for the selective oxidation of glycerol. And the higher amount of acid sites on the surface of Pt/R-WO3 enhanced the selectivity of glyceric acid. The calculated turnover frequency of each Pt atom in Pt/R-WO3 reached 946 h–1 at 60 °C.
- Yang, Lihua,Jiang, Yuanyuan,Zhu, Zihui,Hou, Zhaoyin
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- Efficient Catalysts for the Green Synthesis of Adipic Acid from Biomass
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Green synthesis of adipic acid from renewable biomass is a very attractive goal of sustainable chemistry. Herein, we report efficient catalysts for a two-step transformation of cellulose-derived glucose into adipic acid via glucaric acid. Carbon nanotube-supported platinum nanoparticles are found to work efficiently for the oxidation of glucose to glucaric acid. An activated carbon-supported bifunctional catalyst composed of rhenium oxide and palladium is discovered to be powerful for the removal of four hydroxyl groups in glucaric acid, affording adipic acid with a 99 % yield. Rhenium oxide functions for the deoxygenation but is less efficient for four hydroxyl group removal. The co-presence of palladium not only catalyzes the hydrogenation of olefin intermediates but also synergistically facilitates the deoxygenation. This work presents a green route for adipic acid synthesis and offers a bifunctional-catalysis strategy for efficient deoxygenation.
- Deng, Weiping,Yan, Longfei,Wang, Binju,Zhang, Qihui,Song, Haiyan,Wang, Shanshan,Zhang, Qinghong,Wang, Ye
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supporting information
p. 4712 - 4719
(2021/01/20)
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- PROCESS FOR PRODUCTION OF FORMIC ACID AND ACETIC ACID BY ABSORBING CO2 VIA PHOTOCATALYTIC REDUCTION, IMPROVED CATALYST AND APPARATUS
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The present invention relates to a process for converting CO2 to short chain organic acids, which comprises the steps of: a) dissolution of silver containing fulvate chlatrate komplex catalyst in water to produce a catalyst solution; b) charging the catalyst solution into a pressure reactor; c) introducing a CO2 source into the reactor; d) exposing the reactor space with sunlight or artificial light, or electromagnetic wave while measuring the concentration of the produced organic acids; e) repeating the steps of c) and d) until the concentration of the produced organic acids reaches 2 to 5 % by weight in the reaction mixture; f) if the concentration of the produced organic acids reaches 2-5% by weight, collecting the aqueous solution from the, filtering and concentrating the same. The present invention also relates to a silver-containing fulvate-clathrate complex catalyst.
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Paragraph 0080
(2021/05/29)
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- Electrochemical oxidation of diclofenac on CNT and M/CNT modified electrodes
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The electrochemical oxidation of diclofenac (DCF), a non-steroidal anti-inflammatory drug considered as an emerging pollutant (frequently detected in wastewater), was investigated on CNT, Pt/CNT and Ru/CNT modified electrodes based on Carbon Toray in aqueous media. The electroreactivity of DCF on these modified electrodes was studied using cyclic voltammetry and the kinetic parameters were calculated from the scan rate study. Cyclic voltammograms show several oxidation processes, which confirm the interaction between DCF and the catalyst surface necessary for direct oxidation processes. Constant potential electrolysis of DCF was carried out on carbon nanotubes (CNT) and metal supported CNT (M/CNT) modified electrodes, in 0.1 M NaOH and 0.1 M Na2CO3/NaHCO3buffer media. The highest DCF conversion (88% after 8 h of electrolysis) was found in carbonate buffer medium, for Ru/CNT, while the best carbon mineralization efficiency (corresponding to 48% of the oxidized DCF) was obtained on Pt/CNT modified electrode in 0.1 M NaOH medium. The products of the electrolyses were identified and quantified by HPLC-MS, GC-MS, HPLC-UV-RID and IC. The results show the presence of some low molecular weight carboxylic acids, confirming the cleavage of the aromatic rings during the oxidation process.
- Ferreira, M.,Figueiredo, J. L.,Fonseca, A. M.,Güney, S.,Ku?niarska-Biernacka, I.,Neves, I. C.,Parpot, P.,Pereira, M. F. R.,Soares, O. S. G. P.
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p. 12622 - 12633
(2021/07/25)
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- Earth-abundant manganese oxide nanoneedle as highly efficient electrocatalyst for selective glycerol electro-oxidation to dihydroxyacetone
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In this study, earth-abundant manganese oxide (MnO2) was used as a catalyst for the electrocatalytic glycerol oxidation with a satisfactory yield and high selectivity under mild pH media; that is, the high current density of 6.0 mA cm?2 and selectivity of ca. 46% for dihydroxyacetone (DHA). MnO2 also exhibited reasonable durability without considerable changes for 3 h. More importantly, by combination of operando Raman and electrochemical studies, a tentative reaction pathway was also proposed. It is found that high selectivity of formic acid at low potential was due to predominant coverage of α-MnO2 on catalyst surface. Meanwhile, at high applied potential, partial transformation of α-MnO2 to δ-MnO2 causes decreasing C-C bond cleavage, leading to high DHA selectivity. The results of this work not only demonstrate that MnO2 holds promise as an efficient electrocatalyst for selectively producing DHA but also provides realistic details on electrochemically generated species under working condition.
- Chiang, Chia-Ying,Tran, Giang-Son,Vo, Truong-Giang
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p. 139 - 148
(2021/10/07)
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- METHOD FOR PREPARING GLYCOLIC ACID
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Provided is a method for preparing glycolic acid which comprises oxidizing glycolaldehyde with molecular oxygen in the presence of a solvent and a supported catalyst. Said supported catalyst comprises (i) a noble metal selected from the group consisting of Pt, Pd, Ru and Rh, (ii) Bi and (iii) a support. Advantageously, the supported metallic catalyst is more active than the catalysts used in prior art. Furthermore, the catalyst is more stable at oxygen rich conditions.
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Page/Page column 6
(2021/01/23)
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- A METHOD OF OXIDIZING GLYCOLALDEHYDE USING NITRIC ACID
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The present invention relates to a method of synthesizing at least one organic acid comprising oxidizing glycolaldehyde with nitric acid in the presence of a solvent. Advantageously, it is an industrially applicable process, which prepares organic acid, notably glycolic acid and/or glyoxylic acid in a high yield based on bio-based feedstocks.
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Page/Page column 8
(2020/12/29)
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- Preparation method of glycolic acid or glycolate
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The invention discloses a preparation method of glycolic acid or glycolate. The method comprises the following steps of: formaldehyde and carbon monoxide are introduced into a reactor containing a reaction solution to carry out polymerization reaction, wherein the reaction solution contains an acid catalyst; after the relative molecular mass of a polymer generated by the polymerization reaction reaches 2,000 and above, the polymerization reaction system is cooled to crystallize and precipitate the generated polymer; solid-liquid separation is carried out on the material in the reactor; and excessive water or alcohol is added into the obtained solid phase to carry out a depolymerization reaction to obtain glycolic acid or glycolate. Compared with the prior art, the method disclosed by the invention is good in process stability, low in energy consumption, good in economic practicability and high in product yield, and has a very good application prospect.
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Paragraph 0102-0131
(2020/09/20)
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- Glycerol Selective Oxidation to Lactic Acid over AuPt Nanoparticles; Enhancing Reaction Selectivity and Understanding by Support Modification
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A high surface area mesoporous TiO2 material (110 m2/g) was synthesised using a nanocasting methodology, utilizing SBA-15 as a hard template. This material was subsequently used as a support to prepare a series of 1 wt.% AuPt/TiO2 catalysts, synthesised by conventional impregnation and sol-immobilisation. Catalysts were tested for the oxidation of glycerol to lactic acid and their performance was compared with corresponding catalysts supported on TiO2?P25, TiO2-anatase and TiO2-rutile. Higher rates of reaction and higher selectivity to lactic acid were observed over nanocast TiO2 supported catalysts. The increased performance of these catalysts was attributed to the presence of Si on the surface of the support, which likely arose from inefficient etching of the SBA-15 template. The presence of Si in these catalysts was confirmed by X-ray photoelectron spectroscopy and electron energy loss spectroscopy. It was proposed that the residual Si present increases the Br?nsted acidity of the TiO2 support, which can lead to the formation of Lewis acid sites under reaction conditions; both sites are known to catalyse the dehydration of a primary alcohol in glycerol. Typically, under alkaline conditions, lactic acid is formed by the nucleophilic abstraction of a hydrogen. Thus, we propose that the improved selectivity to lactic acid over the nanocast TiO2 supported catalyst is attributed to the co-operation of heterogeneous and homogeneous dehydration reactions, as both compete directly with a direct oxidation pathway, which leads to the formation of oxidation products such as glyceric and tartronic acid.
- Douthwaite, Mark,Ford, Grayson,Garcia, Tomas,He, Qian,López, José Manuel,Morgan, David J.,Powell, Natasha,Sanahuja-Parejo, Olga,Solsona, Benjamin,Taylor, Aoife,Taylor, Stuart H.,Yang, Nating
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- Plasmonic Oxidation of Glycerol Using Au/TiO2 Catalysts Prepared by Sol-Immobilisation
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Abstract: Au nanoparticles supported on P25 TiO2 (Au/TiO2) were prepared by a facile sol-immobilisation method and investigated for the surface plasmon-assisted glycerol oxidation under base-free conditions. The Au/TiO2 samples were characterized by UV–vis spectroscopy and transmission electron microscopy. Catalysts were prepared using polyvinyl alcohol as stabiliser as well as in the absence of polymer stabiliser. Both the conversion and the reaction selectivity are affected by the plasmon-assisted oxidation and there is an interplay between the presence of the stabiliser and the Au nanoparticle size. Graphic Abstract: [Figure not available: see fulltext.].
- Abis, Laura,Dimitratos, Nikolaos,Sankar, Meenakshisundaram,Freakley, Simon J.,Hutchings, Graham J.
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- Tuning product selectivity in the catalytic oxidation of glycerol by employing metal-ZSM-11 materials
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Copper and chromium supported on ZSM-11 (MEL-type structure) microporous zeolites were investigated as catalysts for glycerol oxidation towards dihydroxyacetone and lactic acid. ZSM-11 was synthesized by hydrothermal crystallization. Subsequently, alkaline treatment of desilication was carried out in order to generate zeolites with micro-mesoporosity. Ion exchange with ammonium chloride was performed to recover acidic sites and then, Cr(iii) and Cu(ii) species were incorporated onto these materials. Finally, thermal treatment at 500 °C was carried out. These materials were characterized by different techniques and then evaluated in the glycerol oxidation reaction by employing H2O2 as an oxidizing agent. The maximum conversion of glycerol (~70%) was reached over the Cr-ZSM-11 catalyst with a selectivity of ~28% towards dihydroxyacetone. Meanwhile, Cu-ZSM-11 offered 50% glycerol conversion with a selectivity of 68% towards lactic acid. In both the cases, the optimal reaction conditions were studied to maximize the selectivity towards the products mentioned above.
- Diguilio, Eliana,Galarza, Emilce D.,Domine, Marcelo E.,Pierella, Liliana B.,Renzini, María S.
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p. 4363 - 4375
(2020/03/26)
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- Preparation of AuPd/ZnO-CuO for the directional oxidation of glycerol to DHA
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Selective activation of the C-O bond of glycerol is a considerable challenge in current academic research. Herein, we fabricate an efficient AuPd/ZnO-CuO catalystviaa simple precipitation method and use it in the selective oxidation of glycerol (GLY) to produce dihydroxyacetone (DHA). Under base-free conditions, the AuPd/ZnO-CuO catalyst exhibits preferable catalytic performance compared with AuPd/ZnO and AuPd/CuO. The turnover frequency (TOF) of AuPd/ZnO-CuO reaches 687.1 h?1, which is 25 times that of AuPd/CuO and 6 times that of AuPd/ZnO. The AuPd/ZnO-CuO catalyst also shows good selectivity toward DHA and the highest DHA yield of 65.3%, which is at the top level among the reported results. Through STEM-EDS, XRD and Raman analyses, we find that ZnO-CuO is a composite oxide and that Zn and Cu elements in the ZnO-CuO support are uniformly distributed. Furthermore, HRTEM, EPR, and XPS results show that AuPd/ZnO-CuO has smaller AuPd alloy nanoparticles (NPs) but a higher concentration of surface defect sites compared with AuPd/ZnO and AuPd/CuO. Together with the catalytic performance and feasible mechanism, we consider that the enhanced performance of the AuPd/ZnO-CuO catalyst could be mainly ascribed to the rich surface defect sites, which facilitate the adsorption and activation of the secondary hydroxyl groups of glycerol.
- Zhao, Gengqiang,Wu, Guandong,Liu, Yanan,He, Yufei,Feng, Junting,Li, Dianqing
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p. 6223 - 6234
(2020/10/14)
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- Electrochemical oxidation of amoxicillin on carbon nanotubes and carbon nanotube supported metal modified electrodes
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The electrolysis of amoxicillin (AMX) was carried out on CNT, Pt/CNT and Ru/CNT modified electrodes based on Carbon Toray in 0.1 M NaOH, 0.1 M NaCl and 0.1 M Na2CO3/NaHCO3 buffer (pH 10) media with the aim of studying the significance of two factors, electrode material and pH, on the oxidative degradation and mineralization of AMX. For this purpose, the electrolysis products were identified by HPLC-MS and GC–MS, and quantified by HPLC-UV-RID and IC. The highest carbon mineralization efficiency, corresponding to 30% of the oxidized AMX, was found for Pt/CNT modified electrode in carbonate buffer medium. Regarding to the AMX conversion, the results show that the effect of pH is higher than that of the electrode material. Principal component analysis allowed to determine the experimental parameters vs. product distribution relationship and to elucidate the oxidation pathways for the studied electrodes. The results show that the hydroxylation of the aromatic ring and the nitrogen atom play an important role on the efficient degradation of AMX.
- Ferreira, Marta,Kuzniarska-Biernacka, Iwona,Fonseca, António M.,Neves, Isabel C.,Soares, Olívia S.G.P.,Pereira, Manuel F.R.,Figueiredo, José L.,Parpot, Pier
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p. 322 - 331
(2019/07/10)
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- Toward glucuronic acid through oxidation of methyl-glucoside using PdAu catalysts
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The production of glucuronic acid via enzyme catalysis from biomass is slow. Here we studied the oxidation of methoxy-protected glucose (MG) using Pd-on-Au nanoparticle model catalysts to generate methoxy-protected glucuronic acid (MGA), a precursor to glucuronic acid. Pd-on-Au showed volcano-shape activity dependence on calculated Pd surface coverage (sc). The 80 sc% Pd-on-Au catalyst composition showed maximum initial turnover frequency (413 mol-MG mol-surface-atom?1 h?1) that was 5× higher than that of Au/C, while Pd/C was inactive. This Pd-on-Au composition gave the highest MGA yield (46%), supporting a bimetallic approach to glucuronic acid production.
- Yin, Y. Ben,Chen, Li,Heck, Kimberly N.,Zhang, Z. Conrad,Wong, Michael S.
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- Glycerol Oxidation Catalyzed by High-valency Ruthenium Species at Electrochemical Interfaces
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Herein we report high-valency ruthenium (Ru) species as a new class of electrocatalyst for glycerol oxidation. In this study, Ru-modified covalent triazine framework (Ru-CTF) and ruthenium oxide supported on carbon (RuO2/C) were used as model materials with high-valency Ru species. The results of this work show that the deep oxidation reactions of glycerol involving C-C bond cleavage can be effectively suppressed by increasing the glycerol concentration relative to the number of active Ru atoms for both catalysts.
- Harada, Takashi,Iwase, Kazuyuki,Kamiya, Kazuhide,Kato, Shintaro,Nakanishi, Shuji,Tabata, Hiro,Yamaguchi, Shingi
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supporting information
p. 513 - 516
(2020/05/18)
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- Iridium-Catalyzed Selective Cross-Coupling of Ethylene Glycol and Methanol to Lactic Acid
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An atom-economic approach that has an unprecedented high selectivity for the synthesis of lactic acid (LA) based on a catalytic dehydrogenative cross-coupling by using inexpensive bulk ethylene glycol and methanol is described. This method relies on the synthesis and utilization of a novel iridium catalyst bearing three N-heterocyclic carbenes derived from 1,3-dimethylbenzimidazolium salts, and exhibits outstanding activity in the production of LA [turnover frequency (TOF) up to 3660 h?1] owing to an elegant metal–ligand cooperation.
- Chen, Zhe-Ning,Shen, Lingyun,Tu, Tao,Wu, Jiajie,Xu, Xin,Zheng, Qingshu
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supporting information
p. 10421 - 10425
(2020/04/15)
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- Bi-Functional Magnesium Silicate Catalyzed Glucose and Furfural Transformations to Renewable Chemicals
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Bio-refinery is attracting significant interest to produce a wide range of renewable chemicals and fuels from biomass that are alternative to fossil fuel derived petrochemicals. Similar to petrochemical industries, bio-refinery also depends on solid zeolite catalysts. Acid-base catalysis plays pivotal role in producing a wide range of chemicals from biomass. Herein, the Mg framework substituted MTW zeolite is synthesized and explored in the valorisation of glucose and furfural. Bi-functional (acidic and basic) characteristics are confirmed using pyridine adsorbed FT?IR analysis and NH3 and CO2 temperature-programmed desorption techniques. Textural properties and morphological information are retrieved from N2-sorption, X-ray photoelectron spectroscopy, and electron microscopy. The activity of the catalyst is demonstrated in the selective isomerisation of glucose to fructose in ethanol. Glucose is converted to methyl lactate in high yield using the same catalyst. Further, the bi-functional activity of this catalyst is demonstrated in the production of fuel precursor by the reaction of furfural and isopropanol. Mg?MTW zeolite exhibits excellent activity in the production of all these chemicals and fuel derivative. The catalyst exhibits no significant loss in the activity even after five recycles. One simple catalyst affording three renewable synthetic intermediates from glucose and furfural will attract significant attention to catalysis researchers and industrialists.
- Kumar, Abhinav,Srivastava, Rajendra
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p. 4807 - 4816
(2020/08/24)
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- Room temperature and atmospheric pressure aqueous partial oxidation of ethane to oxygenates over AuPd catalysts
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New modes of chemical manufacturing based on small-scale, distributed facilities have been proposed to supplement many existing production operations in the chemical industry, including the synthesis of value-added products from light alkanes. Motivated by this prospect, herein the aqueous partial oxidation of ethane over unsupported AuPd nanoparticle catalysts is investigated, with emphasis on outcomes for reactions occurring at 21 °C and 1 bar ethane. When H2O2 is used as an oxidant, the system generates numerous C2 oxygenates, including ethyl hydroperoxide/ethanol, acetaldehyde, and acetic acid. Ethyl hydroperoxide is found to be the primary product resulting from the direct oxidation of ethane: it is produced with 100% selectivity in batch reactions with short durations and with low initial H2O2 concentrations. At longer times or in more oxidizing conditions, deeper product oxidations expectedly occur. In batch experiments, the maximum observed yield of oxygenates is 7707 μmol gAuPd-1 h-1. Product distributions differ when H2O2 is replaced by H2 and O2 in the headspace. Additionally, to simulate a scenario wherein H2O2 is produced on-site and to study ethane oxidation in steady, low H2O2 concentrations over 50 h, a semi-batch configuration facilitating continuous injection of dilute H2O2 was implemented. These efforts showed that H2O2 can serve as an oxygenate-selective oxidant of ethane when its concentration is kept low during reaction. These and other experimental results, as well as initial computational results using density functional theory, suggest that paths forward for aqueous ethane conversion exist, and systems should be engineered to emphasize product stabilization.
- Felvey, Noah,Gurses, Sadi,Kronawitter, Coleman X.,Wang, Yu Lei
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p. 6679 - 6686
(2020/11/16)
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- Aluminum(III) triflate-catalyzed selective oxidation of glycerol to formic acid with hydrogen peroxide
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Glycerol is a by-product of biodiesel production and is an important readily available platform chemical. Valorization of glycerol into value-added chemicals has gained immense attention. Herein, we carried out the conversion of glycerol to formic acid and glycolic acid using H2O2 as an oxidant and metal (III) triflate-based catalytic systems. Aluminum(III) triflate was found to be the most efficient catalyst for the selective oxidation of glycerol to formic acid. A correlation between the catalytic activity of the metal cations and their hydrolysis constants (Kh) and water exchange rate constants was observed. At 70 °C, a formic acid yield of up to 72% could be attained within 12 h. The catalyst could be recycled at least five times with a high conversion rate, and hence can also be used for the selective oxidation of other biomass platform molecules. Reaction kinetics and 1H NMR studies showed that the oxidation of glycerol (to formic acid) involved glycerol hydrolysis pathways with glyceric acid and glycolic acid as the main intermediate products. Both the [Al(OH)x]n+ Lewis acid species and CF3SO3H Br?nsted acid, which were generated by the in-situ hydrolysis of Al(OTf)3, were responsible for glycerol conversion. The easy availability, high efficiency, and good recyclability of Al(OTf)3 render it suitable for the selective oxidation of glycerol to high value-added products.
- Kong, Kang,Li, Difan,Ma, Wenbao,Zhou, Qingqing,Tang, Guoping,Hou, Zhenshan
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p. 534 - 542
(2019/04/03)
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- Sustainable Co-Synthesis of Glycolic Acid, Formamides and Formates from 1,3-Dihydroxyacetone by a Cu/Al2O3 Catalyst with a Single Active Sites
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Glycolic acid (GA), as important building block of biodegradable polymers, has been synthesized for the first time in excellent yields at room temperature by selective oxidation of 1,3-dihyroxyacetone (DHA) using a cheap supported Cu/Al2O3 catalyst with single active CuII species. By combining EPR spin-trapping and operando ATR-IR experiments, different mechanisms for the co-synthesis of GA, formates, and formamides have been derived, in which .OH radicals formed from H2O2 by a Fenton-like reaction play a key role.
- Dai, Xingchao,Adomeit, Sven,Rabeah, Jabor,Kreyenschulte, Carsten,Brückner, Angelika,Wang, Hongli,Shi, Feng
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supporting information
p. 5251 - 5255
(2019/03/07)
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- Glycerol Partial Oxidation over Pt/Al2O3 Catalysts under Basic and Base-Free Conditions—Effect of the Particle Size
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The glycerol partial oxidation reaction over Pt/Al2O3 catalysts was studied under basic (NaOH/GLY molar ratio 4) and base-free conditions (NaOH/GLY molar ratio 0). Catalysts with small (2.95 nm) and large particle sizes (260.83 nm) were synthesized according to the use of different reducing agents, formaldehyde or sodium borohydride, and hydrazine, respectively. These different Pt particle sizes lead to a dramatic change in terms of activity, irrespective of the applied conditions. The biggest particles (i.e., 260 nm) seem to generate overoxidation products leading to a decrease in the carbon balance (to ~80%) while the smallest particles exhibit the highest initial glycerol transformation rate (i.e., ~10,000 mol h?1 molPt?1 under basic conditions at 60°C and ~2000 mol h?1 molPt?1 in the absence of a base at 100°C). In terms of selectivities, the main products are different as a function of the initial reaction conditions. For base-free conditions, the two main products are glyceraldehyde and glyceric acid with a sum of selectivities always larger than 80%. Under basic conditions, the major product is glyceric acid while no trace of glyceraldehyde is detected.
- Skrzyńska, El?bieta,El Roz, Ayman,Paul, Sébastien,Capron, Micka?l,Dumeignil, Franck
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- The Enhanced Catalytic Performance and Stability of Ordered Mesoporous Carbon Supported Nano-Gold with High Structural Integrity for Glycerol Oxidation
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Ordered mesoporous carbon (OMC) supported gold nanoparticles of size 3–4 nm having uniform dispersion were synthesized by sol-immobilization method. OMCs such as CMK-3 and NCCR-56 with high surface area and uniform pore size were obtained, respectively, using ordered mesoporous silicas such as SBA-15 and IITM-56 as hard templates, respectively. The resulting OMC supported monodispersed nano-gold, i. e., Au/CMK-3 and Au/NCCR-56, exhibited excellent performance as mild-oxidizing catalysts for oxidation of glycerol with high hydrothermal stability. Further, unlike activated carbon supported nano-gold catalysts (Au/AC), the OMC supported nano-gold catalysts, i. e., Au/CMK-3 and Au/NCCR-56, show no aggregation of active species even after recycling. Thus, in the case of Au/CMK-3 and Au/NCCR-56, both the fresh and regenerated catalysts showed excellent performane for the chosen reaction owing to an enhanced textural integrity of the catalysts and that with remarkable selectivity towards glyceric acid. The significance of the OMC supports in maintaining the dispersion of gold nanoparticles is explicit from this study, and that the activity of Au/AC catalyst is considerably decreased (~50 %) upon recycling as a result of agglomeration of the active gold nanoparticles over the disordered amorphous carbon matrix.
- Murthy, Palle R.,Selvam, Parasuraman
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p. 1913 - 1925
(2018/11/27)
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- Selective oxidation of glycerol to tartronic acid over Pt/N-doped mesoporous carbon with extra framework magnesium catalysts under base-free conditions
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N-Doped mesoporous carbons (NMCs) with extra framework magnesium were prepared by a one-pot method and used as supports for Pt catalysts. The surface basicity of NMC improved in the presence of extra framework magnesium (e.g.,-Ph-O-Mg), meanwhile, the electron density of Pt was enriched by the electron transfer from graphitic N in NMC to Pt. As a result, the catalytic activity of the supported Pt catalyst was improved to be able to selectively oxidize glycerol (GLY) to tartronic acid (TA) under base-free conditions.
- Zhan, Tong,Liu, Weibing,Teng, Junjiang,Yue, Chaochao,Li, Dehao,Wang, Suhua,Tan, Hua
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supporting information
p. 2620 - 2623
(2019/03/05)
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- Cu/C-catalyzed Hydrogenolysis of Sorbitol to Glycols–On the Influence of Particle Size and Base
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Herein, a series of Cu catalysts supported on activated carbon with increasing particle size was tested for the conversion of sorbitol to glycols including 1,2-propanediol and ethylene glycol in the presence of Ca(OH)2. Activity measurements reveal a distinct correlation between TOF and particle size, which increases until 14 nm (N2O chemisorption based) after which a plateau is reached. However, variation of the particle size has no apparent effect on the selectivity for C3/C3 and C2/C4 cleavage. In contrast, variation of the Ca(OH)2 equivalence has a profound impact on selectivity. The ratio of C3/(C2+C4) products reaches an optimum at 0.45 equiv. of Ca(OH)2. Notably, the time course of the reaction demonstrates that the by-products lactic acid and glycerol are in-situ converted to the desired product 1,2-propanediol, contributing to the unprecedented combined glycol selectivity of 84.5 % at 513 K, 5 MPa H2 and 0.3 equiv. of Ca(OH)2. Furthermore, recycling tests reveal a rapid deactivation which is attributed to aggregation of Cu observed in TEM.
- Wang, Xinde,Beine, Anna Katharina,Hausoul, Peter J. C.,Palkovits, Regina
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p. 4123 - 4129
(2019/05/27)
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- PtII-Catalyzed Hydroxylation of Terminal Aliphatic C(sp3)?H Bonds with Molecular Oxygen
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The practical application of Shilov-type Pt catalysis to the selective hydroxylation of terminal aliphatic C?H bonds remains a formidable challenge, due to difficulties in replacing PtIV with a more economically viable oxidant, particularly O2. We report the potential of employing FeCl2 as a suitable redox mediator to overcome the kinetic hurdles related to the direct use of O2 in the Pt reoxidation. For the selective conversion of butyric acid to γ-hydroxybutyric acid (GHB), a significantly enhanced catalyst activity and stability (turnover numbers (TON)>30) were achieved under 20 bar O2 in comparison to current state-of-the-art systems (TON0 was prevented by the addition of monodentate pyridine derivatives, such as 2-fluoropyridine, but also by introducing varying partial pressures of N2 in the gaseous atmosphere. Finally, stability tests revealed the involvement of PtII and FeCl2 in catalyzing the non-selective overoxidation of GHB. Accordingly, in situ esterification with boric acid proved to be a suitable strategy to maintain enhanced selectivities at much higher conversions (TON>60). Altogether, a useful catalytic system for the selective hydroxylation of primary aliphatic C?H bonds with O2 is presented.
- Janssen, Michiel,De Vos, Dirk E.
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supporting information
p. 10724 - 10734
(2019/07/15)
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- Efficient and stable platinum nanocatalysts supported over Ca-doped ZnAl2O4 spinels for base-free selective oxidation of glycerol to glyceric acid
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In the work, highly dispersed platinum nanocatalysts supported over undoped and Ca-doped zinc aluminate spinels were developed and applied for aqueous-phase selective oxidation of glycerol to produce glyceric acid under base-free conditions. As-fabricated Pt-based catalyst with the incorporation of an appropriate Ca/(Ca + Zn) molar ratio of 0.1 into the spinel exhibited a higher catalytic activity, along with a selectivity to glyceric acid (>81%) and a high turnover frequency of 1160 h?1, compared with other supported Pt-based ones over zinc aluminates, as well as most of supported Pt catalysts previously reported. The structural characterizations and catalytic experiments showed that surface synergy between highly dispersed metallic Pt0 species and medium-strength basic sites mainly contributed to its enhanced catalytic efficiency for base-free glycerol oxidation. Moreover, the present Pt catalyst also presented high structural stability and good reusability. The work opens an alternative approach for constructing highly efficient and stable metal-base bifunctional catalysts for a wide range of heterogeneous oxidation processes without the addition of liquid alkalis.
- Han, Zhengya,Xie, Renfeng,Song, Yihui,Fan, Guoli,Yang, Lan,Li, Feng
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- Quantitative Determination of Pt- Catalyzed d -Glucose Oxidation Products Using 2D NMR
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Quantitative correlative 1H-13C NMR has long been discussed as a potential method for quantifying the components of complex reaction mixtures. Here, we show that quantitative HMBC NMR can be applied to understand the complexity of the catalytic oxidation of glucose to glucaric acid, which is a promising bio-derived precursor to adipic acid, under aqueous aerobic conditions. It is shown through 2D NMR analysis that the product streams of this increasingly studied reaction contain lactone and dilactone derivatives of acid products, including glucaric acid, which are not observable/quantifiable using traditional chromatographic techniques. At 98% glucose conversion, total C6 lactone yield reaches 44%. Furthermore, a study of catalyst stability shows that all Pt catalysts undergo product-mediated chemical leaching. Through catalyst development studies, it is shown that sequestration of leached Pt can be achieved through use of carbon supports.
- Armstrong,Hirayama,Knight,Hutchings
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p. 325 - 335
(2019/01/04)
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- Selective oxidation of monoethanolamine to glycine over supported gold catalysts: The influence of support and the promoting effect of polyvinyl alcohol
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Glycine is an important fine chemical used in many fields, and the traditional synthetic methods like Strecker synthesis and ammoniation of chloroacetic acid use highly toxic reagents or produce equal molar byproducts. Herein, selective aerobic oxidation of monoethanolamine (MEA) to glycine using Au catalysts supported on various supports, including Al2O3, SiO2, TiO2, ZnO, and ZrO2, was investigated and the correlation between acid-base properties of the catalysts and catalytic performance was established. Catalysts with higher base content exhibited higher initial activity and that with lower acid content gave higher glycine selectivity. The influence of preparation methods was revealed using Au/ZrO2 with the best catalytic performance and it was demonstrated that the presence of polyvinyl alcohol (PVA) has a significant promoting effect. In-situ FTIR and 1H NMR analysis revealed that the hydrogen bonds between PVA and MEA can enhance adsorption of MEA on catalysts, resulting in doubled turnover frequency (TOF) and improved MEA conversion; and the preferential hydrogen bonds between the amino group of MEA and the hydroxyl of PVA can prevent the coordination of amino group with Au nanoparticles, favoring reaction of the hydroxyl group of MEA on the active sites, accounting for the enhanced glycine selectivity. The reaction conditions were optimized and the optimal yield of glycine was 95%.
- Meng, Xiangzhan,Bai, Yinge,Xu, Haiyang,Zhang, Yongqiang,Li, Chunshan,Wang, Hui,Li, Zengxi
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p. 131 - 143
(2019/03/26)
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- Production of propylene glycol (1,2-propanediol) by the hydrogenolysis of glycerol in a fixed-bed downflow tubular reactor over a highly effective Cu-Zn bifunctional catalyst: Effect of an acidic/basic support
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In this study, different acidic (V2O5, ZrO2, and TiO2) and basic (CaO and MgO) oxide-supported copper-zinc bimetallic catalysts were prepared by a deposition-precipitation method, and they were evaluated for the vapor-phase hydrogenolysis of glycerol to propylene glycol at 0.1 MPa and at 220 °C. The catalysts were thoroughly characterized by different techniques such as BET, XRD, H2-TPR, NH3 and CO2 TPD, N2O adsorptive decomposition, TEM, XPS, FE-SEM and TGA. Among all the supported catalysts, the Cu-Zn/MgO catalyst was found to be the most selective to propylene glycol. High copper-metal dispersion (~5%), surface area (~23 m2 g-1), the highest basicity (0.25 mmol CO2 g cat-1) and the availability of partially reduced copper species (Cu2O, CuO and Cu0) were the primary reasons for the higher propylene glycol selectivity. At optimum reaction conditions, i.e., at 220 °C, 0.72 MPa and a weight hourly space velocity (WHSV) of 0.073 h-1, ~98.5% conversion of glycerol with ~89% selectivity to propylene glycol was obtained over the Cu-Zn/MgO catalyst. This catalyst was also found to be stable for a long period of time (84 h) without much deactivation and without decrease in the selectivity to propylene glycol.
- Pandey, Dinesh Kumar,Biswas, Prakash
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p. 10073 - 10086
(2019/07/03)
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- Polyoxomolybdates catalysed cascade conversions of cellulose to glycolic acid with molecular oxygen via selective aldohexoses pathways (an epimerization and a [2+4] Retro-aldol reaction)
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Selective cascade conversion of cellulose into valuable C2 or C4 products over acid catalysts is still not fully explored because glucose-fructose isomerization followed by fructose conversions is thermodynamically easy to occur during the reaction, leading the formation of C6, C5, C3 and C1 products such as 5-hydroxymethylfurfural (HMF), levulinates, lactates, formates, and so on. In this study, phosphomolybdates (PMo) with the Keggin structure was found to promote cascade oxidation of cellulose conversion via selective aldohexoses pathways, i.e. an epimerization and a [2 + 4] retro-aldol of glucose/mannose, rather than aldo-ketohexoses routes, i.e. a glucose-fructose isomerization and a [3 + 3] retro-aldol of fructose, which produced glycolic acid (GlycA) (C2) as the main product (~50% selectivity). Either in aerobic or anaerobic state, PMo selectively catalyzed glucose epimerization into mannose at 100 °C. This behavior is completely different from that of molybdate in MoO3 which is only effective for the epimerization reaction (the Bilik reaction). In this cascade oxidation reaction, PMo was reduced into heteropoly-blue (PMored) as observed by the color change of the solution, UV-VIS and FT-IR measurements. In this case, the molecular oxygen was found to reoxidize PMored into PMo, leading the catalytic activity to be remained stable. The results shown in this study provide an insight for the catalyst development on selective synthesis of C2, C4 and/or other novel valuable chemicals from carbohydrates via the aldohexose pathways.
- Bayu, Asep,Karnjanakom, Surachai,Yoshida, Akihiro,Kusakabe, Katsuki,Abudula, Abuliti,Guan, Guoqing
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- Selective formation of formic acid from biomass-derived glycolaldehyde with supported ruthenium hydroxide catalysts
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Ceria-supported ruthenium hydroxide catalysts, Ru(OH)x/CeO2, comprising micro- A nd nanoparticle supports were prepared, characterized and examined for the catalytic aerobic oxidation of glycolaldehyde (GAD) to formic acid (FA) in water under mild and base-free conditions. Under optimized reaction conditions, both of the examined catalyst types gave a high FA yield of around 80% at full GAD conversion with low CO2 formation (>95% carbon balance), while intermediate oxidation products were obtained under milder conditions and humins dominated under harsher conditions. The nanoparticle catalysts were more active than analogous catalysts based on microparticle ceria, which had a lower BET surface area and lower content of surface Ru(OH)x species relative to other Ru species. Notably, the superior nanoparticle-based catalyst also proved to be reusable in three consecutive reaction runs with essentially unchanged catalytic performance. This study demonstrates a benign and green protocol to convert GAD-a versatile platform molecule obtainable from biomass-derived carbohydrates-into the large-volume commodity chemical FA which has multiple industrial applications.
- Modvig,Riisager
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p. 4384 - 4392
(2019/08/21)
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- Characterization of a new nitrilase from Hoeflea phototrophica DFL-43 for a two-step one-pot synthesis of (S)-β-amino acids
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A nitrilase from Hoeflea phototrophica DFL-43 (HpN) demonstrating excellent catalytic activity towards benzoylacetonitrile was identified from a nitrilase tool-box, which was developed previously in our laboratory for (R)-o-chloromandelic acid synthesis from o-chloromandelonitrile. The HpN was overexpressed in Escherichia coli BL21 (DE3), purified to homogeneity by nickel column affinity chromatography, and its biochemical properties were studied. The HpN was very stable at 30–40?°C, and highly active over a wide range of pH values (pH 6.0–10.0). In addition, the HpN could tolerate against several hydrophilic organic solvents. Steady-state kinetics indicated that HpN was highly active towards benzoylacetonitrile, giving a KM of 4.2?mM and a kcat of 170?s?1, the latter of which is ca. fivefold higher than the highest record reported so far. A cascade reaction for the synthesis of optically pure (S)-β-phenylalanine from benzoylacetonitrile was developed by coupling HpN with an ω-transaminase from Polaromonas sp. JS666 in toluene-water biphasic reaction system using β-alanine as an amino donor. Various (S)-β-amino acids could be produced from benzoylacetonitrile derivatives with moderate to high conversions (73–99%) and excellent enantioselectivity (> 99% ee). These results are significantly advantageous over previous studies, indicating a great potential of this cascade reaction for the practical synthesis of (S)-β-phenylalanine in the future.
- Zhang, Zhi-Jun,Cai, Rui-Feng,Xu, Jian-He
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p. 6047 - 6056
(2018/05/15)
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- Unraveling the mechanism of the oxidation of glycerol to dicarboxylic acids over a sonochemically synthesized copper oxide catalyst
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The utilization of low frequency ultrasound (US) offers a straightforward and powerful tool for the production of nanostructured materials, in particular for structurally stable, highly crystalline, and shape-controlled catalytic materials. Herein, we report an unconventional strategy for the synthesis of CuO nanoleaves within 5 min of US irradiation. The as-obtained CuO nanoleaves were found to be selective in the base-free aqueous oxidation of glycerol to dicarboxylic acids (78% yield of tartronic and oxalic acids), in the presence of hydrogen peroxide (H2O2) and under mild reaction conditions. Density Functional Theory (DFT) investigations revealed a synergy between the CuO catalyst and H2O2 in maintaining the structural integrity of the catalyst during the reaction, creating alternative efficient pathways for the selective formation of dicarboxylic acids. Isotope labeling experiments using H218O2 further confirmed that oxygen from hydrogen peroxide, not from CuO, was preferentially incorporated into the dicarboxylic acid, significantly preserving the monoclinic structure of the CuO catalyst.
- Amaniampong, Prince N.,Trinh, Quang Thang,Varghese, Jithin John,Behling, Ronan,Valange, Sabine,Mushrif, Samir H.,Jér?me, Francois
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supporting information
p. 2730 - 2741
(2018/06/29)
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- Promoting effect of solvent on Cu/CoO catalyst for selective glycerol oxidation under alkaline conditions
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Cu/CoO catalysts were employed for the selective oxidation of glycerol in the aqueous phase under basic conditions. The effect of the solvent on the catalytic performance was investigated and the impact on the catalyst was thoroughly elucidated. Detailed characterization of the catalysts by HR-TEM, XRD, and XPS analysis before and after the reaction revealed that the addition of co-solvents (ethanol, n-propanol, or tert-butanol) drastically altered the catalyst properties. In particular, the amount of the catalytically active CoO(OH) phase generated during the reaction depends on the co-solvent used. Generally, the co-solvent has a beneficial effect on the catalytic activity and improves the glycerol conversion by a factor of up to 1.8, which could be linearly correlated to the ET(30) solvent polarity.
- Dodekatos, Georgios,Ternieden, Jan,Schünemann, Stefan,Weidenthaler, Claudia,Tüysüz, Harun
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p. 4891 - 4899
(2018/10/24)
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- Glycerol Oxidation Using MgO- and Al2O3-supported Gold and Gold–Palladium Nanoparticles Prepared in the Absence of Polymer Stabilizers
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Au and AuPd nanoparticles supported on MgO and Al2O3 were employed for the selective aqueous phase oxidation of glycerol under basic conditions. Catalysts were prepared by sol-immobilization without the addition of a stabilizing agent such as polyvinyl alcohol (PVA), which is generally added to stabilize the noble metal sol prior to immobilization. The obtained materials prepared with and without stabilizing agent were active for glycerol oxidation and showed similar catalytic performances—implying that the stabilizing polymer is not required to obtain active materials. Depending on the support used, it was possible to tailor the selectivity towards the desired oxidation products by using catalysts prepared with or without stabilizing agent. PVA-free Au/γ-Al2O3 exhibited a remarkably high selectivity towards tartronic acid (40 % at 97 % conversion), which was not observed for Au/γ-Al2O3 prepared with PVA (27 % at isoconversion). Selective glycerol oxidation performed under base-free conditions over AuPd/MgO catalysts also corroborated the previous results that the presence of a stabilizing polymer is not required to prepare active catalysts by sol-immobilization. Thus, a facile way to circumvent the inherent drawbacks encountered by the use of polymer stabilizers during catalyst preparation is presented herein. Experimental results suggest that the presence of the polymer stabilizers can affect the reaction pathways and control selectivity.
- Dodekatos, Georgios,Abis, Laura,Freakley, Simon J.,Tüysüz, Harun,Hutchings, Graham J.
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p. 1351 - 1359
(2018/03/30)
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- Gold-Doped Fe/TiO2 Catalysts: A Case of Extra-Low Gold Loading in Glycerol Oxidation
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Abstract: Au/Fe/TiO2 catalysts with a low Au content ( 16 000.
- Redina,Vikanova,Shesterkina,Kustov
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p. 2143 - 2147
(2018/10/24)
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- Synergetic effects of bimetals in modified beta zeolite for lactic acid synthesis from biomass-derived carbohydrates
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An experimental study was carried out to convert carbohydrates using bimetal modified beta zeolite to obtain a maximum yield of lactic acid. The relationship between the properties and the catalytic performance of various bimetal modified beta zeolites was evaluated. The results showed that the maximum yield of lactic acid reached 52% with more than 99% glucose conversion over Pb-Sn-beta (0.3 mmol g-1, Pb/Sn = 4:7) at 190 °C for 2 h under ambient air pressure. To evaluate the synergetic mechanism of lead and tin, key intermediates such as fructose, dihydroxyacetone, glyceraldehyde and pyruvaldehyde were used as probe reactants that were catalyzed by Pb-beta, Sn-beta and Pb-Sn-beta. The revealed key role of lead was to promote the isomerization of glucose to fructose and the retro-aldol condensation reaction from fructose to dihydroxyacetone and glyceraldehyde; meanwhile, tin had a superior catalytic performance in the dehydration of dihydroxyacetone, the hydration of pyruvaldehyde and the isomerization of pyruvic aldehyde hydrate.
- Xia, Meng,Dong, Wenjie,Gu, Minyan,Chang, Cheng,Shen, Zheng,Zhang, Yalei
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p. 8965 - 8975
(2018/03/08)
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- The Role of Mg(OH)2 in the So-Called “Base-Free” Oxidation of Glycerol with AuPd Catalysts
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Mg(OH)2- and Mg(OH)2-containing materials can provide excellent performance as supports for AuPd nanoparticles for the oxidation of glycerol in the absence of base, which is considered to be a result of additional basic sites on the surface of the support. However, its influence on the reaction solution is not generally discussed. In this paper, we examine the relationship between the basic Mg(OH)2 support and AuPd nanoparticles in detail using four types of catalyst. For these reactions, the physical interaction between Mg(OH)2 and AuPd was adjusted. It was found that the activity of the AuPd nanoparticles increased with the amount of Mg(OH)2 added under base-free conditions, regardless of its interaction with the noble metals. In order to investigate how Mg(OH)2 affected the glycerol oxidation, detailed information about the performance of AuPd/Mg(OH)2, physically mixed (AuPd/C+Mg(OH)2) and (AuPd/C+NaHCO3) was obtained and compared. Furthermore, NaOH and Mg(OH)2 were added during the reaction using AuPd/C. All these results indicate that the distinctive and outstanding performance of Mg(OH)2 supported catalysts in base-free condition is in fact directly related to its ability to affect the pH during the reaction and as such, assists with the initial activation of the primary alcohol, which is considered to be the rate determining step in the reaction.
- Fu, Jile,He, Qian,Miedziak, Peter J.,Brett, Gemma L.,Huang, Xiaoyang,Pattisson, Samuel,Douthwaite, Mark,Hutchings, Graham J.
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supporting information
p. 2396 - 2402
(2018/02/06)
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- Formation of Chiral Structures in Photoinitiated Formose Reaction
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The possibility to synthesize biologically important sugars and other chiral compounds without any initiators in the UV-initiated reaction of formaldehyde in aqueous solution has been shown for the first time. An optically active condensed phase due to an
- Stovbun,Skoblin,Zanin,Tverdislov,Taran,Parmon
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p. 108 - 116
(2018/04/05)
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- A METHOD AND A SYSTEM FOR PRODUCING GLYCOLIC ACID AND/OR GLYCOLATE
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A method and a system for producing glycolic acid and/or glycolate from sustainable resources.
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Page/Page column 10
(2018/06/12)
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