- 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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- 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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- 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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- 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 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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- 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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- 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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- Method for synthesizing tartronic acid by using basic nitrogen-doped mesoporous carbon-material-supported Pt catalyst
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The invention discloses a method for synthesizing tartronic acid by using a basic nitrogen-doped mesoporous carbon-material-supported Pt catalyst. The method comprises the following steps: s1, preparing a nitrogen-doped mesoporous carbon material with a -Ph-O-Mg or -Ph-O-Ca structure; s2, preparing the basic nitrogen-doped mesoporous carbon-material-supported Pt catalyst by utilizing the nitrogen-doped mesoporous carbon material; and s3, catalyzing oxidation of glycerol by using the basic nitrogen-doped mesoporous carbon-material-supported Pt catalyst so as to prepare tartronic acid. The catalyst provided by the invention is adopted to catalyze the oxidation of glycerol to prepare tartronic acid, and has the advantages of simple and diverse synthesis methods, wide raw material sources, lowcost, strong alkalinity, mild reaction conditions, high stability and easiness in recycling.
- -
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Paragraph 0047-0079
(2019/12/29)
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- METHOD FOR PRODUCING CARBOXYLIC ACID
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PROBLEM TO BE SOLVED: To produce carboxylic acid from glycerol at a temperature lower than or equal to a boiling point of a solvent, using a catalyst that is easy to recover and reuse. SOLUTION: A method for producing carboxylic acid has a production step that produces carboxylic acid by a reaction between glycerol and oxygen-containing gas in the presence of a catalyst and an alkali metal. The catalyst is obtained through a mixture step for mixing a gold ion, a platinum ion, and a metal oxide in acidic liquid. The ratio of the mass of gold ions to the sum of the mass of gold ions and the mass of platinum ions is higher than 0.2 and lower than 0.8. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
- -
-
Paragraph 0021-0024; 0027
(2019/04/11)
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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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- 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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- Method for preparing propanoldiacid by catalytic oxidation of glycerol
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The invention discloses a method for preparing propanoldiacid by catalytic oxidation of glycerol. Catalytic oxidation of glycerol is carried out under mild and non-alkaline conditions with a Pt-supported potassium-modified nitrogen-doped mesoporous carbon material as a catalyst to prepare the propanoldiacid in one step, and the mild conditions are: a reaction temperature of below 60 DEG C and normal pressure. A nitrogen-doped mesoporous carbon material is modified with potassium, so the alkalinity of the carrier is improved; the supported Pt-based catalyst is prepared by using the potassium-modified nitrogen-doped mesoporous carbon material as a carrier, so the catalytic oxidation activity of the Pt catalyst is improved; and the propanoldiacid is prepared in one step by the catalytic oxidation of glycerol under mild and non-alkaline conditions, so the use of alkalis and the occurrence of related side reactions are avoided.
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Paragraph 0049; 0051; 0054; 0055; 0060; 0065; 0070; 0081
(2019/01/07)
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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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- Influence of Pt Particle Size on the Activity of Pt/AC Catalyst in Selective Oxidation of Glycerol to Lactic Acid
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Abstract: The size effect of Pt particles on selective oxidation of glycerol to lactic acid was investigated over 1.0?wt% Pt/activated carbon catalysts in base solutions. A series of Pt/activated carbon catalysts with Pt particle size ranging from 10.2 to 3.8?nm were prepared by simply verifying the deposition–precipitation temperature from 0 to 80 °C, which were characterized by XRD, CO pulse chemisorption, H2–O2 titration, TEM and zeta potential analyses. The Pt particle size showed evident impact on the pseudo turnover frequency of the catalyst, with the optimal activity achieved over medium-sized Pt particles. The lactic acid selectivity was less obviously affected by the Pt particle size. Meanwhile, the Pt particle size effect would be altered when factors including base type changed. Graphical Abstract: [Figure not available: see fulltext.].
- Zhang, Chen,Wang, Tao,Ding, Yunjie
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p. 1197 - 1203
(2017/05/12)
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- One-step synthesis of pyruvic acid from glycerol oxidation over Pb promoted Pt/activated carbon catalysts
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One-step production of pyruvic acid through selective oxidation of glycerol was investigated using lead promoted platinum/activated carbon (Pb-Pt/AC) catalysts under mild conditions. The results of N2 physisorption, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy revealed that the alloy phases of PtPb and PtxPb were favorable for pyruvic acid production from glycerol oxidation, whereas the Pb3(CO3)2(OH)2 and surface Pb0 species inhibited the glycerol conversion. The loading of Pb and the catalyst preparation method (including impregnation and deposition precipitation) affected the formation of different metal species. Pyruvic acid was obtained at a yield of 18.4% on a 5.0 wt% Pb-5.0 wt% Pt/AC catalyst prepared by co-deposition precipitation method and 500 °C argon treatment.
- Zhang, Chen,Wang, Tao,Ding, Yunjie
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p. 928 - 937
(2017/05/22)
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- A switchable route to valuable commodity chemicals from glycerol via electrocatalytic oxidation with an earth abundant metal oxidation catalyst
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Electrocatalytic upgrading of glycerol to value-added commodity is demonstrated using an ultralow loading of a cobalt-based oxidation catalyst at 16 μg cm-2. Reactions take place under ambient conditions in an aqueous environment, while generating H2 as a byproduct. Selectivity towards two major products, lactic acid and glyceric acid, can be controlled via simple variation of reaction conditions. The system is scalable and functions well even in the presence of methanol, an impurity commonly found in the industrial bio-diesel waste stream. Industrial glycerol waste from a local bio-diesel plant was also shown to be upgradable after a simple aqueous pretreatment.
- Lam, Chun Ho,Bloomfield, Aaron J.,Anastas, Paul T.
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p. 1958 - 1968
(2017/06/09)
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- Efficient Generation of Lactic Acid from Glycerol over a Ru-Zn-CuI/Hydroxyapatite Catalyst
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The biodiesel production process generates a significant amount of glycerol as a byproduct. A drive to add value has attracted worldwide attention, with the aim of improving the overall effectiveness and profitability of biodiesel production. Herein, we report hydroxyapatite (HAP)-supported Ru-Zn-CuI (Ru-Zn-CuI/HAP) as effective catalysts for the transformation of glycerol to lactic acid (LA).The catalysts were characterized by using different techniques. The effects of catalyst composition, reaction time, and temperature on the conversion and product distribution were investigated. It was revealed that Ru nanoparticles of less than 2 nm were dispersed uniformly on HAP. CuI could effectively inhibit the cleavage of C?C bonds, which led to improved yields of LA. Under optimized conditions, the yield of LA could reach 70.9 % over Ru-Zn-CuI/HAP. Furthermore, the catalyst could be reused at least four times without an obvious loss of activity or selectivity.
- Jiang, Zhiwei,Zhang, Zhanrong,Wu, Tianbin,Zhang, Pei,Song, Jinliang,Xie, Chao,Han, Buxing
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p. 1598 - 1604
(2017/07/11)
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- Lattice distortion induced electronic coupling results in exceptional enhancement in the activity of bimetallic PtMn nanocatalysts
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Lattice strain plays a critical role in structural heterogeneity and surface electronic properties of bimetallic nanocatalysts. However, understanding of how to engineer optimal electron transfer in anisotropic bimetallic crystals remains a grand challenge to achieve enhanced catalytic performances. We investigate beyond conventional polymer based core-shell and alloy structures, and present unique lattice distorted PtMn catalysts fabricated via a cooperative self-assembly method. The strong internal strain between Pt and Mn lattices is found to induce the structural distortion of anisotropic PtMn crystals and formation of asymmetric flower shapes, leading to stretched Pt and contracted Mn lattices. Such distorted bimetallic crystals exhibit unusual electronic coupling and an eight-fold synergistic enhancement in catalytic oxidation of renewable biomass feedstocks compared with monometallic Pt catalysts. The novel synthesis technique and revealed electronic coupling mechanism described herein opens the door for the rational discovery of other bimetallic nanocatalysts with positive synergy.
- Jin, Xin,Zeng, Chun,Yan, Wenjuan,Zhao, Meng,Bobba, Pallavi,Shi, Honghong,Thapa, Prem S.,Subramaniam, Bala,Chaudhari, Raghunath V.
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-
- Effect of Post-Treatment on Structure and Catalytic Activity of CuCo-based Materials for Glycerol Oxidation
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A series of CuCo-based materials prepared by co-precipitation with varied Co/Cu ratios and different post-treatments were applied in the selective oxidation of glycerol in the aqueous phase under basic conditions. The influence of the post-treatment on the structure of the materials and the catalytic performance was investigated in detail. As-prepared materials without calcination and materials calcined under air with subsequent reduction under ethanol/N2 gas stream showed higher conversion of glycerol compared to samples solely calcined under air or to samples calcined under air with subsequent reduction under H2/Ar gas stream. The main products identified in the liquid phase were glyceric, glycolic, and formic acids. Systematic catalytic studies for differently prepared samples with varied Cu content and subsequent characterization of the materials by N2 physisorption, XRD, TEM, and EDX allowed for the identification of CoO(OH) in contact with CuO as the potentially active phases.
- Dodekatos, Georgios,Tüysüz, Harun
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p. 610 - 619
(2017/02/26)
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- Au/CuMgAl-hydrotalcite catalysts promoted by Cu+ and basic sites for selective oxidation of glycerol to dihydroxyacetone
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CuMgAl-hydrotalcite-supported Au catalysts were prepared and tested in the selective conversion of glycerol to dihydroxyacetone. The electron density of Au was decreased by Cu embedded in the supports, arising from the electron transfer from Au to Cu sites. The valence state (+?1) of Cu ions was detected. Both Cu+ and basic sites (Mg–O) affected the catalytic activity of Au catalysts. The Cu+ sites promoted the selective oxidation of glycerol to dihydroxyacetone, while basic sites boosted the selectivity oxidation of glycerol to glyceric acid. The synergy of Cu+ sites and basic sites could effectively promote the activity and selectivity of Au catalysts in the selectively conversion of glycerol to dihydroxyacetone. A 53% conversion of glycerol and 72% of dihydroxyacetone selectivity were obtained under optimum reaction conditions.
- Yin, Yanrui,Tang, Tian,Xu, Chunli
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p. 319 - 326
(2017/12/12)
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- Electrochemical production of lactic acid from glycerol oxidation catalyzed by AuPt nanoparticles
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The production of valuable chemicals from relatively inexpensive feedstocks utilizing electrochemical methods has been attracting widespread attention in recent years since it is highly efficient, decentralized, environmental-friendly and can operate in room temperature and pressure. Currently, the industrial production of lactic acid is mainly based on bio-fermentation, leading to drawbacks including severe conditions, unfriendliness to environment, low efficiency and requirement of expensive equipment, which can potentially overcome by electrochemical methods. Herein, we report for the first time the preparation of lactic acid at room temperature and pressure from the one-pot electro-oxidation of glycerol, a byproduct from biodiesel production. AuPt nanoparticles with different surface compositions were employed in this work to optimize the catalysis performance, and the glycerol oxidation was operated at a series of applied potentials, pH and glycerol concentration. The optimal lactic acid selectivity was 73%, obtained with Au-enriched surface at applied potential of 0.45 V vs. RHE.
- Dai, Chencheng,Sun, Libo,Liao, Hanbin,Khezri, Bahareh,Webster, Richard D.,Fisher, Adrian C.,Xu, Zhichuan J.
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- Green oxidation of bio-lactic acid with H2O2 into tartronic acid under UV irradiation
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Tartronic acid (TA) is a high value-added chemical widely used as a pharmaceutical product and a preservative; however, its synthesis technology is complicated and high cost. In this study, aqueous solutions of lactic acid were photochemically converted into TA via green oxidation by using hydrogen peroxide (H2O2).
- Tian, Xuxia,Wang, Zhijian,Yang, Pengju,Hao, Ruipeng,Jia, Suping,Li, Na,Li, Li,Zhu, Zhenping
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p. 41007 - 41010
(2016/05/19)
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- Nanoscale Pd-based catalysts for selective oxidation of glycerol with molecular oxygen: Structure–activity correlations
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This work investigates selective oxidation of glycerol with molecular oxygen, one of the viable routes to obtain value-added products from bio-glycerol, using nanosized Pd-based catalysts. For this, three types of 1 wt.% Pd catalysts supported on activated carbon (Ac), hydrotalcite (HTc), and activated carbon–hydrotalcite composite (Ac–HTc) were prepared. The physicochemical properties of the catalysts are characterized using various techniques, such as XRD, BET, XRF, H2-TPR, CO2-TPD, and TEM. The TEM images reveal the formation of Pd nanoparticles with an average diameter of 9.01, 9.10, and 11.16 nm on the surface of HTc, Ac, and Ac–HTc supports, respectively. The CO2-TPD results show that the Pd@HTc catalyst exhibits higher concentration of basic sites compared with that of Pd@HTc-Ac and Pd@Ac catalysts. The H2-TPR profiles show that the reducibility of Pd species is highly dependent on the nature of the supports. Catalytic activity results reveal that the conversion of glycerol over Pd catalysts increased in the following order: Pd/Ac Pd@HTc-Ac Pd@HTc, while selectivity of the glyceric acid increased in the following order: Pd@HTc-Ac Pd@Ac Pd@HTc. The presence of more number of basic sites and high dispersion of Pd nanoparticles are found to be key factors for excellent catalytic performance of Pd@HTc catalyst in the oxidation of glycerol with molecular oxygen.
- Hamid, Sharifah Bee Abd,Basiron, Norfatehah,Yehye, Wageeh A.,Sudarsanam, Putla,Bhargava, Suresh K.
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p. 124 - 133
(2016/12/06)
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- Highly selective transformation of glycerol to dihydroxyacetone without using oxidants by a PtSb/C-catalyzed electrooxidation process
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We demonstrate an electrocatalytic reactor system for the partial oxidation of glycerol in an acidic solution to produce value-added chemicals, such as dihydroxyacetone (DHA), glyceraldehyde (GAD), glyceric acid (GLA), and glycolic acid (GCA). Under optimized conditions, the carbon-supported bimetallic PtSb (PtSb/C) catalyst was identified as a highly active catalyst for the selective oxidation of glycerol in the electrocatalytic reactor. The product selectivity can be strongly controlled as a function of the applied electrode potential and the catalyst surface composition. The main product from the electrocatalytic oxidation of glycerol was DHA, with a yield of 61.4% of DHA at a glycerol conversion of 90.3%, which can be achieved even without using any oxidants over the PtSb/C catalyst at 0.797 V (vs. SHE, standard hydrogen electrode). The electrocatalytic oxidation of biomass-derived glycerol represents a promising method of chemical transformation to produce value-added molecules.
- Lee, Seonhwa,Kim, Hyung Ju,Lim, Eun Ja,Kim, Youngmin,Noh, Yuseong,Huber, George W.,Kim, Won Bae
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supporting information
p. 2877 - 2887
(2016/05/24)
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- Pt catalysts for efficient aerobic oxidation of glucose to glucaric acid in water
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Glucaric acid, a promising bio-based chemical for the production of adipic acid, is produced on a commercial Pt/C catalyst via aerobic oxidation of glucose in water. Facile oxidation of gluconic acid, an intermediate oxidation product of glucose, under optimal conditions of an initial pH of 7.2, 80 °C, 13.8 bar O2 and a glucose/Pt molar ratio of 54, enabled a maximum glucaric acid yield of 74%, the highest yield reported to date. It is found that in an acidic solution, gluconic acid is the major product while in a highly basic solution, selectivity to glucaric acid is poor due to its C-C bond cleavage to low carbon chain carboxylic acids. High temperatures and high Pt loadings result in lower selectivity to glucaric acid. Recyclability and characterization studies reveal that the catalyst is stable after five cycles with no sign of Pt leaching into the solution.
- Lee, Jechan,Saha, Basudeb,Vlachos, Dionisios G.
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p. 3815 - 3822
(2016/07/07)
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- Electrooxidation of glycerol on nickel and nickel alloy (Ni-Cu and Ni-Co) nanoparticles in alkaline media
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In the present study, nickel (Ni) and Ni alloy (Ni-Cu and Ni-Co) nanoparticles modified carbon-ceramic electrodes (Ni/CCE, Ni-Cu/CCE and Ni-Co/CCE) were prepared by an electrochemical process for the oxidation of glycerol. In order to obtain the surface and physicochemical information, the Ni/CCE, Ni-Cu/CCE and Ni-Co/CCE were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and electrochemical techniques. Then, cyclic voltammetry and chronoamperometry were employed to characterize the electrocatalytic activity of the modified electrodes, Ni/CCE, Ni-Cu/CCE and Ni-Co/CCE, toward the oxidation of glycerol in 1.0 M NaOH solution. It was found that the Ni alloy nanoparticle modified electrodes are catalytically more active than the Ni/CCE, therefore, the alloying of the Ni with Cu and Co in the form of nanoparticles on the carbon-ceramic electrode, as a homemade substrate, greatly enhances the catalytic activity of the Ni-based electrocatalysts (as the non-platinum electrocatalysts) in glycerol oxidation.
- Habibi, Biuck,Delnavaz, Nasrin
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p. 31797 - 31806
(2016/04/26)
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- Oxidation of Glycerol to Dicarboxylic Acids Using Cobalt Catalysts
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In this paper, the performance of cobalt-based catalysts was reported for oxidation of glycerol to dicarboxylic acids such as tartronic and oxalic acids. Cobalt catalysts supported on Mg3Al(OH)y(CO3)z structures prepared by a two-step modified sol-gel method showed 100% glycerol conversion with 64% and 24% selectivity toward tartronic and oxalic acids under mild conditions (55-70 °C and 0.1 MPa O2). Surface and bulk characterization by N2 adsorption/desorption, X-ray diffraction, and temperature-programmed reduction reveals that the cobalt sites interacting with surface hydroxides are catalytically more active than those incorporated into a framework leading to selective glycerol oxidation to dicarboxylic acids in one pot. On the basis of the experiments at different cobalt contents, temperatures, and concentration-time profiles, possible reaction pathways are discussed to explain the selectivity profile. Deactivation of the catalyst under certain conditions has been discussed as a result of loss of surface area due to structural changes.
- Jin, Xin,Zhao, Meng,Zeng, Chun,Yan, Wenjuan,Song, Ziwei,Thapa, Prem S.,Subramaniam, Bala,Chaudhari, Raghunath V.
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p. 4576 - 4583
(2016/07/12)
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- Selective Oxidation of Glycerol to Glyceric Acid in Base-Free Aqueous Solution at Room Temperature Catalyzed by Platinum Supported on Carbon Activated with Potassium Hydroxide
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Pt supported on KOH-activated mesoporous carbon (K-AMC) was used to catalyze glycerol oxidation under base-free conditions at room temperature. To study the relationship between the carbon surface chemistry and the catalytic performance of the K-AMC-based Pt catalysts, different levels of surface oxygen functional groups (SOFGs) on the AMC supports were induced by thermal treatment at different temperatures under inert or H2 gas. A strong effect of the surface chemistry was observed on AMC-supported Pt catalysts for glycerol oxidation. The presence of carboxylic acid groups impedes the adsorption of glycerol, which leads to the reduction of catalytic activity, whereas the presence of high-desorption-temperature SOFGs, such as phenol, ether, and carbonyl/quinone groups, provide hydrophilicity to the carbon surface that improves the adsorption of glycerol molecules on Pt metal surface, which is beneficial for the catalytic activity.
- Tan, Hua,Tall, Omar E.,Liu, Zhaohui,Wei, Nini,Yapici, Tahir,Zhan, Tong,Hedhill, Mohamed Nejib,Han, Yu
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p. 1699 - 1707
(2016/05/19)
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- Au-based catalysts: Electrochemical characterization for structural insights
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Au-based catalysts are widely used in important processes because of their peculiar characteristics. The catalyst performance depends strongly on the nature and structure of the metal nanoparticles, especially in the case of bimetallic catalysts where synergistic effects between the two metals can be occasionally seen. In this paper, it is shown that electrochemical characterisation (cyclovoltammetry CV and electrochemical impedance spectroscopy EIS) of AuPd systems can be used to determine the presence of an electronic interaction between the two metals, thus providing a strong support in the determination of the nature of the synergy between Au and Pd in the liquid phase oxidation of alcohols. However, it seems likely that the strong difference in the catalytic behavior between the single metals and the bimetallic system is connected not only to the redox behaviour, but also to the energetic balance between the different elementary steps of the reaction.
- Pifferi, Valentina,Chan-Thaw, Carine E.,Campisi, Sebastiano,Testolin, Anna,Villa, Alberto,Falciola, Luigi,Prati, Laura
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- SUPPORTED METAL CATALYST AND USE THEREOF FOR SELECTIVE OXIDATION OF GLYCEROL
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A method for oxidation of glycerol into glyceric acid is described, which includes a step of treating glycerol with a supported metal catalyst in the presence of oxygen, said catalyst including platinum and a metal element selected from the group comprising tin, molybdenum, bismuth and a mixture thereof.
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Paragraph 0082-0084
(2016/10/11)
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- Metal nanoparticles on carbon based supports: The effect of the protective agent removal
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The sol immobilization technique is widely employed for the synthesis of size- and morphology-controlled supported nanoparticles. The protective agent adsorbed on the surface of nanoparticles can substantially affect the catalytic performances, by limiting the access to the active sites as well as by influencing metal–support and reactant–metal interactions, thus altering not only the activity but also the selectivity of the reaction. Herein, we studied the effect of the capping agent (specifically polyvinyl alcohol, PVA) removal on the catalytic activity and selectivity of gold nanoparticles supported on different carbon based materials using the glycerol oxidation as test reaction.
- Campisi, Sebastiano,Chan-Thaw, Carine E.,Wang, Di,Villa, Alberto,Prati, Laura
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- Palladium catalysed oxidation of glycerol - Effect of catalyst support
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The activity and selectivity of Palladium catalysts on various supports, for the liquid-phase oxidation of glycerol in basic condition, have been studied. Activated carbon (AC), SiO2, Al2O3 and TiO2 were the supports studied. The catalysts were characterized using a variety of techniques (TEM, BET, Pulse-Chemisorption, TPD, TPR and XPS). The support is shown to have a significant effect on both rate and selectivity of the reaction, with the best rate of glycerol conversion, as well as selectivity to glyceric acid, being obtained for activated carbon (AC) among all the supports studied. The results have been interpreted in terms of known concepts of metal-support interactions. It is concluded that the electronic interactions between the metal and support, as well as acidic/basic properties of catalyst, play a vital role in product selectivity and activity.
- Namdeo, Ashutosh,Mahajani,Suresh
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- For glycerol catalytic oxidation method for preparing propanol II acid
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The invention provides a method of preparing propanoldiacid through catalytic oxidation of glycerol. The method uses a noble metal supported catalyst for high-efficient catalytic oxidation of the glycerol to directly generate the propanoldiacid under a mild condition, with a temperature being 20-80 DEG C and a pressure being 0.3-3.0 MPa. A conversion rate of the glycerol reaches more than 99 %, and a catalyst selectivity reaches 95 %. The method is high-efficient and environmental-protective, and has a relatively large application prospect.
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Paragraph 0036; 0037
(2017/04/11)
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- Combined EC-NMR and in Situ FTIR Spectroscopic Studies of Glycerol Electrooxidation on Pt/C, PtRu/C, and PtRh/C
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Glycerol, a byproduct of biodiesel production, is an industrial waste because of its excess yield. Electrooxidation of glycerol is a promising way to utilize glycerol - through harvesting electric energy as fuels in a fuel cell or hydrogen as sacrificial agent in electrolysis cell - while generating valuable chemicals. Here, we report a detailed mechanistic study of the glycerol electrooxidation reaction (GOR) on a series of Pt/C, PtxRuy/C, and PtxRhy/C nanocatalysts synthesized by NaBH4 reduction. The EC cyclic voltammetry characterization indicates that alloying Ru with Pt greatly enhanced the GOR activity, especially at low potential, but not as much with alloying Rh, as compared with Pt/C. In situ FTIR and 13C NMR spectroscopies were used to investigate the GOR mechanism at a molecular level. The results demonstrate that the selectivity of products depends on the type of catalysts and the oxidation potential. Although both PtRu/C and PtRh/C could accelerate the oxygen insertion reactions that led to higher selectivity of carboxylic acids, tartronic acid was more favored at high potential on the PtRh/C surface. (Chemical Equation Presented).
- Huang, Long,Sun, Jia-Yu,Cao, Shuo-Hui,Zhan, Mei,Ni, Zu-Rong,Sun, Hui-Jun,Chen, Zhong,Zhou, Zhi-You,Sorte, Eric G.,Tong, YuYe J.,Sun, Shi-Gang
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p. 7686 - 7695
(2016/11/17)
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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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p. 307 - 316
(2016/05/11)
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- Selective oxidation of glycerol to lactic acid over activated carbon supported Pt catalyst in alkaline solution
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Pt/activated carbon (Pt/AC) catalyst combined with base works efficiently for lactic acid production from glycerol under mild conditions. Base type (LiOH, NaOH, KOH, or Ba(OH)2) and base/glycerol molar ratio significantly affected the catalytic performance. The corresponding lactic acid selectivity was in the order of LiOH > NaOH > KOH > Ba(OH)2. An increase in LiOH/glycerol molar ratio elevated the glycerol conversion and lactic acid selectivity to some degree, but excess LiOH inhibited the transformation of glycerol to lactic acid. In the presence of Pt/AC catalyst, the maximum selectivity of lactic acid was 69.3% at a glycerol conversion of 100% after 6 h at 90 °C, with a LiOH/glycerol molar ratio of 1.5. The Pt/AC catalyst was recycled five times and was found to exhibit slightly decreased glycerol conversion and stable lactic acid selectivity. In addition, the experimental results indicated that reaction intermediate dihydroxyacetone was more favorable as the starting reagent for lactic acid formation than glyceraldehyde. However, the Pt/AC catalyst had adverse effects on the intermediate transformation to lactic acid, because it favored the catalytic oxidation of them to glyceric acid.
- Zhang, Chen,Wang, Tao,Liu, Xiao,Ding, Yunjie
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p. 502 - 509
(2016/04/20)
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- Glycerol oxidation in liquid phase: Highly stable Pt catalysts supported on ion exchange resins
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The glycerol oxidation reaction in liquid phase was studied using platinum supported on ion exchange resin as catalysts, with the objective of obtaining glyceric acid. In particular, the effect of the competitor anion, which is the ion used during the support pre-treatment, was addressed. It was found that the competitor ion affects the radial distribution of the active metal in the resin sphere. As the adsorption equilibrium constant of the competitor ion increases, the penetration of platinum in the resin particle also increases. Nevertheless, this difference did not affect the catalytic performance. However, the presence of iodide as competitor ion affected the platinum chemical environment, thus modifying the platinum active sites in this catalyst. Such effect was not observed when chloride or citrate ions were used for the resin pretreatment. Therefore, the competitor ion effect on the platinum catalysts performance is related with the ion nature more than with its affinity for the resin exchange sites. Iodide is adsorbed by platinum, and consequently, it affects its electronic state improving the selectivity. These catalysts showed very good activity, and what is also very important, very good stability, being possible to maintain the conversion and selectivity for many reaction cycles.
- Gross, Martín S.,Sánchez, Bárbara S.,Querini, Carlos A.
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- Selective oxidation of glycerol over carbon nanofibers supported Pt catalysts in a base-free aqueous solution
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Highly dispersed Pt nanoparticles were fabricated on the surface of S-grafted carbon nanofibers (Pt/S-CNFs) and used in selective oxidation of glycerol with molecular oxygen in a base-free aqueous solution. Haracterizations disclosed that S-grafted CNFs are more favorable for the dispersion of Pt than that of crude CNFs and HNO3-pretreated CNFs. CNFs supported Pt catalysts are more selective toward the formation of glycerin acid, and the initial activity of surface Pt atoms in Pt/S-CNFs reached 750.7 h?1 at 60 °C in a base-free aqueous solution.
- Zhang, Mengyuan,Nie, Renfeng,Wang, Lina,Shi, Juanjuan,Du, Weichen,Hou, Zhaoyin
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- Tailoring gold nanoparticle characteristics and the impact on aqueous-phase oxidation of glycerol
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Poly(vinyl alcohol) (PVA)-stabilized Au nanoparticles (NPs) were synthesized by colloidal methods in which temperature variations (-75 to 75 °C) and mixed H2O/EtOH solvent ratios (0, 50, and 100 vol/vol) were used. The resulting Au NPs were immobilized on TiO2 (P25), and their catalytic performance was investigated for the liquid phase oxidation of glycerol. For each unique solvent system, there was a systematic increase in the average Au particle diameter as the temperature of the colloidal preparation increased. Generation of the Au NPs in H2O at 1 °C resulted in a high observed activity compared with current Au/TiO2 catalysts (turnover frequency = 915 h-1). Interestingly, Au catalysts with similar average particle sizes but prepared under different conditions had contrasting catalytic performance. For the most active catalyst, aberration-corrected high angle annular dark field scanning transmission electron microscopy analysis identified the presence of isolated Au clusters (from 1 to 5 atoms) for the first time using a modified colloidal method, which was supported by experimental and computational CO adsorption studies. It is proposed that the variations in the populations of these species, in combination with other solvent/PVA effects, is responsible for the contrasting catalytic properties.
- Rogers, Scott M.,Catlow, C. Richard A.,Chan-Thaw, Carine E.,Gianolio, Diego,Gibson, Emma K.,Gould, Anna L.,Jian, Nan,Logsdail, Andrew J.,Palmer, Richard E.,Prati, Laura,Dimitratos, Nikolaos,Villa, Alberto,Wells, Peter P.
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p. 4377 - 4384
(2015/11/11)
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- PdHx Entrapped in a Covalent Triazine Framework Modulates Selectivity in Glycerol Oxidation
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Pd nanoparticles within a nitrogen-containing covalent triazine framework (CTF) material are investigated to understand if the highly tunable CTF chemistry mediates the catalytic properties of the Pd nanoparticles. Surprisingly, our results demonstrate that the CTF stabilizes the formation of 2.6 nm PdHx particles within the pores. These confined PdHx particles are very active for the liquid-phase oxidation of glycerol and promote C-C cleavage, probably connected with the enhanced in situ formation of H2O2. During recycling tests, the confined particles are transformed progressively to very stable Pd0 particles. This stability has been attributed mainly to a confinement effect as nanoparticles trapped outside the pores lose activity rapidly. These results indicate that there is a potential to tune CTF chemistry to modify the chemistry of the catalytic metals significantly.
- Chan-Thaw, Carine E.,Villa, Alberto,Wang, Di,Santo, Vladimiro Dal,Orbelli Biroli, Alessio,Veith, Gabriel M.,Thomas, Arne,Prati, Laura
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p. 2149 - 2154
(2015/11/24)
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- Effect of Structure and Substituents in the Aqueous Phase Oxidation of Alcohols and Polyols Over Au, Pd, and Au-Pd Catalysts
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Abstract Reactivity trends for oxidation of various alcohols and polyols have been examined for carbon-supported Au, Pd, and Au-Pd catalysts. A Hammett σρ approach was used to study substituent effects, with Hammett factors (ρ) of 1.27, 1.31, and 0.40 obtained for Pd, Au, and Au-Pd catalysts, suggesting the formation of a net negative charge at the transition state of the rate limiting step. The lower ρ for the Au-Pd catalyst versus Au and Pd monometallic catalysts indicates the ability of the Au-Pd catalyst to stabilize the negative charge at the transition state, explaining the improved performance of Au-Pd bimetallic catalysts for alcohol oxidation. Hammett-Taft factors were used to explain the low selectivity of terminal diols and polyols to diacids.
- Rodriguez, Abraham A.,Williams, Christopher T.,Monnier, John R.
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p. 750 - 756
(2015/08/06)
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- Recombinant oxalate decarboxylase: Enhancement of a hybrid catalytic cascade for the complete electro-oxidation of glycerol
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The complete electro-oxidation of glycerol to CO2 is performed through an oxidation cascade using a hybrid catalytic system combining a recombinant enzyme, oxalate decarboxylase from Bacillus subtilis, and an organic oxidation catalyst, 4-amino-TEMPO. This system is capable of electrochemically oxidizing glycerol at a carbon electrode collecting all 14 electrons per molecule.
- Abdellaoui, Sofiene,Hickey, David P.,Stephens, Andrew R.,Minteer, Shelley D.
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p. 14330 - 14333
(2015/09/21)
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- Specific selectivity of Au-catalyzed oxidation of glycerol and other C 3-polyols in water without the presence of a base
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A big challenge in upgrading bio-oxygenate platform molecules is to develop catalysts for the selective oxidation of a nonterminal HO-bonded carbon atom in polyols. We report herein the first finding of a specific selectivity of oxide-supported nano-Au catalysts for dihydroxyacetone (DHA) production in glycerol oxidation in water without NaOH. Though the support nature (Al 2O3, TiO2, ZrO2, NiO, and CuO) significantly affects the Au activity, a highly active Au/CuO catalyst offering DHA yields up to 80% at 40-50 °C has been identified. Rich data are provided to clarify that DHA is the only primary product of glycerol oxidation. This propensity of nano-Au for oxidizing the HO-bonded secondary (central) carbon is further verified by comparing the oxidation of propanediols and propanols. Molecular insight into the reactions is given on the basis of the kinetic isotopic effect study of deuterium on the oxidation of 2-propanol, uncovering an unanticipated chemistry of Au catalysis.
- Liu, Shu-Sen,Sun, Ke-Qiang,Xu, Bo-Qing
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p. 2226 - 2230
(2014/07/21)
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- Degradation of sulfadiazine antibiotics by water falling film dielectric barrier discharge
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A new water falling film dielectric barrier discharge was applied to the degradation of sulfadiazine in the aqueous solution. The various parameters that affect the degradation of sulfadiazine and the proposed evolutionary process were investigated. The results indicated that the inner concentrations of 10 mg/L sulfadiazine can be all removed within 30 min. The optimum pH value was 9.10 and both strong acidic and alkaline solution conditions were not suitable for the degradation. The degradation of sulfadiazine can be enhanced by the addition of hydrogen radical scavengers, but be inhibited by adding hydroxyl radical scavengers. The water falling film dielectric barrier discharge was rather ineffective in mineralization, because of the intermediates were recalcitrant to be degraded. The existence of Fe2+ and CCl 4 in the liquid phase can promote the degradation and mineralization of sulfadiazine. It was found that the degradation of SDZ was enhanced by CCl4 was mainly because of the increase of OH due to the reaction of CCl4 with H that reduce the chances of their recombination with OH. Based on the 8 intermediate products identified by LC-MS, the proposed evolution of the degradation process was investigated.
- Rong, Shao-Peng,Sun, Ya-Bing,Zhao, Ze-Hua
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p. 187 - 192
(2014/02/14)
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- Catalytic oxidation of glycerol to tartronic acid over Au/HY catalyst under mild conditions
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Gold nanoclusters or nanoparticles on various supports (CeO2, activated carbon, HY, REY, and NaY) were investigated for glycerol oxidation in the aqueous phase under mild conditions. Compared with other catalysts, Au/HY showed remarkable catalytic performance in forming dicarboxylic acid (tartronic acid) over the monocarboxylic acid (glyceric acid) or the C-C cleavage product (oxalic acid). Au/HY achieved 98% conversion of glycerol and 80% yield of tartronic acid at 60 °C under 0.3 MPa O2. Further characterization showed that the small size of Au clusters is the key factor for the high oxidation performance. In situ Fourier transform infrared spectroscopy revealed that glycerol was first transformed to glyceric acid, and then glyceric acid was directly oxidized to tartronic acid.
- Cai, Jiaying,Ma, Hong,Zhang, Junjie,Du, Zhongtian,Huang, Yizheng,Gao, Jin,Xu, Jie
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p. 1653 - 1660
(2015/09/28)
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- Influence of silver on the glycerol electro-oxidation over AuAg/C catalysts in alkaline medium: A cyclic voltammetry and in situ FTIR spectroscopy study
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In the present work, we investigated the influence of silver on the glycerol electro-oxidation over carbon-supported AuAg catalysts by cyclic voltammetry and in situ FTIR spectroscopy. We observed that the presence of Ag in the bimetallic materials provided a more efficient catalyst in terms of the ability to electro-oxidize glycerol at relatively low potentials. On the other hand, the bimetallic catalysts were found to be less promising than the Au/C catalyst with respect to the reaction rate. Ag addition influenced the mechanism of glycerol electro-oxidation, favoring the C-C-C bond breaking, as evidenced by the selective formation of formic acid on the bimetallic catalysts. The impact of Ag on the glycerol electro-oxidation over AuAg/C may be driven by electronic modifications and Ag segregation on the catalysts surface.
- Gomes,Garcia,Gasparotto,De Souza,Ferreira,Pires,Tremiliosi-Filho
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p. 361 - 368
(2014/12/10)
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- Titania-based photocatalytic degradation of two nucleotide bases, cytosine and uracil
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The photocatalytic degradation of two components of DNA and RNA, cytosine (C4H5N3O) and uracil (C4H 4N2O2) differing only by the presence of an amine or a carbonyl group was investigated in the presence of UV-irradiated TiO2 aqueous suspensions. The adsorption in the dark and under UV-A conditions, the photolysis, the kinetics of degradation, the fate of nitrogen and the identification of some intermediate products were investigated. The impact of pyrimidine cycles on the coverage of TiO2 under UV-A, the effect of NH2 substituent on the oxidation products and mineralization and the importance of carbonyl and amine groups on the fate of nitrogen atoms were evaluated. Electronic density was used to propose a possible chemical pathway. The comparison of the disappearance and mineralization rates in the photocatalytic process was discussed.
- Elsellami,Sahel,Dappozze,Horikoshi,Houas,Guillard
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p. 207 - 213
(2014/11/27)
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- Base-free oxidation of glycerol using titania-supported trimetallic Au-Pd-Pt nanoparticles
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Base-free selective oxidation of glycerol has been investigated using trimetallic Au-Pd-Pt nanoparticles supported on titania and their corresponding bimetallic catalysts. Catalysts were prepared by the sol-immobilization method and characterized by means of TEM, UV/Vis spectroscopy, diffuse reflectance infrared fourier transform spectroscopy, X-ray photoelectron spectroscopy, and microwave plasma-atomic emission spectroscopy. It was found that of the bimetallic catalysts, Pd-Pt/TiO2 was the most active with high selectivity to C3 products. The addition of Au to this catalyst to form the trimetallic Au-Pd-Pt/TiO2, resulted in an increase in activity relative to Pd-Pt/TiO2. The turnover frequency increased from 210 h-1 with the Pd-Pt/TiO2 catalyst to378 h -1 for the trimetallic Au-Pd-Pt/TiO2 catalyst with retention of selectivity towards C3 products. The noble trio: Base-free selective oxidation of glycerol is investigated using trimetallic Au-Pd-Pt nanoparticles supported on titania and their corresponding bimetallic catalysts. Increased activity is observed for the trimetallic Au-Pd-Pt/TiO 2 catalyst, with retention of selectivity towards C3 products.
- Kondrat, Simon A.,Miedziak, Peter J.,Douthwaite, Mark,Brett, Gemma L.,Davies, Thomas E.,Morgan, David J.,Edwards, Jennifer K.,Knight, David W.,Kiely, Christopher J.,Taylor, Stuart H.,Hutchings, Graham J.
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p. 1326 - 1334
(2014/06/09)
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- Identification of chemicals resulted in selective glycerol conversion as sustainable fuel on Pd-based anode nanocatalysts
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Palladium-based nanoparticles were prepared using mild microwave-assisted heating. The activity of carbon supported PdM (M = Mn and Fe) toward glycerol oxidation in alkaline medium was studied by coupling electrochemical, analytical and in situ spectroscopic techniques. The complementary findings showed that glycerol was converted into oxalate, tartronate, glycerate, glycolate and formate. The ex situ analytical methods (liquid chromatography and mass spectrometry) were helpful to reveal glycerate as the major reaction product on PdM/C anodes, while from in situ infrared spectroscopy measurements no irreversible adsorbed poisoning species was detected in glycerol or intermediate oxidation to carbonate at the prepared electrodes. The correlation of the analytical and physicochemical (XRD, EDX and TEM) results concerned the shift of the onset potential toward lower values and the high Faradaic currents due to electronic structures provided by the Mn and Fe contents to the Pd based materials. Accordingly, glycerol is a sustainable raw material, which can be used in cogeneration processes for renewable energy sources and selective production of added-value molecules.
- Palma,Almeida,Oliveira,Tremiliosi-Filho,Gonzalez,De Andrade,Servat,Morais,Napporn,Kokoh
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p. 64476 - 64483
(2015/04/27)
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- Liquid phase oxidation of glycerol in batch and flow-type reactors with oxygen over Au-Pd nanoparticles stabilized in anion-exchange resin
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Structure-controlled well-dispersed Au-Pd nanoparticles were successfully stabilized in a commercial ion-exchange resin. The so-obtained Au-Pd nanoparticles were tested in liquid phase glycerol partial oxidation in the presence of molecular oxygen. They exhibited better catalytic performances than homologous monometallic Au or Pd catalysts. The optimized bimetallic catalyst trapped in the matrix of the ion-exchange resin was very stable with time on stream (>4000 min) using a fixed bed flow type reactor, with a conversion of ca. 50% and stable selectivities towards glyceric and tartronic acids, of ca. 60% and 30%, respectively. The active phase originated from the presence of nanometric bimetallic nanoparticles (1.0-3.0 nm) characterized by STEM analysis. the Partner Organisations 2014.
- Mimura, Naoki,Hiyoshi, Norihito,Fujitani, Tadahiro,Dumeignil, Franck
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p. 33416 - 33423
(2014/08/18)
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