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Photothermal strategy for the highly efficient conversion of glucose into lactic acid at low temperatures over a hybrid multifunctional multi-walled carbon nanotube/layered double hydroxide catalyst
The conversion of carbohydrates into lactic acid has attracted increasing attention owing to the broad applications of lactic acid. However, the current methods of thermochemical conversion commonly suffer from limited selectivity or the need for harsh conditions. Herein, a light-driven system of highly selective conversion of glucose into lactic acid at low temperatures was developed. By constructing a hybrid multifunctional multi-walled carbon nanotube/layered double hydroxide composite catalyst (CNT/LDHs), the highest lactic acid yield of 88.6% with 90.0% selectivity was achieved. The performance of CNT/LDHs for lactic acid production from glucose is attributed to the following factors: (i) CNTs generate a strong heating center under irradiation, providing heat for converting glucose into lactic acid; (ii) LDHs catalyze glucose isomerization, in which the photoinduced OVs (Lewis acid) in LDHs under irradiation further improve the catalytic activity; and (iii) in a heterogeneous-homogeneous synergistically catalytic system (LDHs-OH-), OH- ions are concentrated in LDHs, forming strong base sites to catalyze subsequent cascade reactions.
Duo, Jia,Jin, Binbin,Jin, Fangming,Shi, Xiaoyu,Wang, Tianfu,Ye, Xin,Zhong, Heng
p. 813 - 822
(2022/02/09)

Catalytic wet air oxidation of D-glucose by perovskite type oxides (Fe, Co, Mn) for the synthesis of value-added chemicals
The conversion of common biomasses derived, as D-glucose, into value-added chemicals has received highest attention in the last few years. Among all processes, the catalytic wet air oxidation (CWAO) of derived biomasses using noble metal-based heterogeneo
Geobaldo, Francesco,Pirone, Raffaele,Russo, Nunzio,Scelfo, Simone
(2022/03/15)

Ambient base-free glycerol oxidation over bimetallic PdFe/SiO2 by in situ generated active oxygen species
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.
p. 303 - 324
(2021/01/07)

Selective Reductive Dimerization of CO2into Glycolaldehyde
The selective dimerization of CO2 into glycolaldehyde is achieved in a one-pot two-step process via formaldehyde as a key intermediate. The first step concerns the iron-catalyzed selective reduction of CO2 into formaldehyde via formation and controlled hydrolysis of a bis(boryl)acetal compound. The second step concerns the carbene-catalyzed C-C bond formation to afford glycolaldehyde. Both carbon atoms of glycolaldehyde arise from CO2 as proven by the labeling experiment with 13CO2. This hybrid organometallic/organic catalytic system employs mild conditions (1 atm of CO2, 25 to 80 °C in less than 3 h) and low catalytic loadings (1 and 2.5%, respectively). Glycolaldehyde is obtained in 53% overall yield. The appealing reactivity of glycolaldehyde is exemplified (i) in a dimerization process leading to C4 aldose compounds and (ii) in a tri-component Petasis-Borono-Mannich reaction generating C-N and C-C bonds in one process.
Zhang, Dan,Jarava-Barrera, Carlos,Bontemps, Sébastien
p. 4568 - 4575
(2021/05/04)

Photocatalytic hydrogenation of nitrobenzene to aniline over titanium(iv) oxide using various saccharides instead of hydrogen gas
Bare TiO2 photocatalyst almost quantitatively converted nitrobenzene to aniline with various saccharides without the use of hydrogen gas. Although aniline was formed when any saccharide was used, the use of disaccharides (lactose, maltose, and sucrose) de
Aono, Yushiro,Ikeuchi, Kazuma,Imamura, Kazuya,Onda, Ayumu,Oto, Takahiro,Sakamoto, Yuki
p. 32300 - 32304
(2021/12/02)

Oxidative Conversion of Glucose to Formic Acid as a Renewable Hydrogen Source Using an Abundant Solid Base Catalyst
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
p. 954 - 959
(2021/07/14)

The selective oxidation of glycerol over metal-free photocatalysts: insights into the solvent effect on catalytic efficiency and product distribution
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
p. 3385 - 3392
(2021/06/06)

Earth-abundant manganese oxide nanoneedle as highly efficient electrocatalyst for selective glycerol electro-oxidation to dihydroxyacetone
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
p. 139 - 148
(2021/10/07)

Tin, molybdenum and tin-molybdenum oxides: Influence of Lewis and Bronsted acid sites on xylose conversion
In this study, tin oxide (SnO2), molybdenum oxide (MoO3) and a mixed oxide based on tin and molybdenum (respectively, Sn100, Mo100 and SnMo25, synthesized by the impregnation method) were applied in xylose conversion. The best results were obtained employing Mo100 and SnMo25. In the presence of SnMo25, after 0.5 h, xylose conversions of 39.5%, 34.1% and 63.4% were obtained, respectively, at 110, 130 and 150 °C. For Mo100, conversions of 49.6%, 71.8% and 85.3% were attained under the same reaction conditions, showing that Mo100 provided the best conversion results. However, with the use of this catalyst there was an increase in the amount of soluble and insoluble polymeric material. In terms of the soluble products formed from xylose, depending on the reaction condition were detected xylulose (X), lyxose (L) and furfural (FUR), glyceraldehyde (GL), pyruvaldehyde (PYR), glycoaldehyde (GLYC), dihydroxyacetone (DHA), lactic acid (AL), levulinic acid (LA) and acetic acid (AA). However, with the use of Sn100 or without a catalyst (systems with low conversions) there was mainly the formation of lyxose. The use of Mo100 and SnMo25 (systems which exhibit high acidity) leads mainly to isomerization, epimerization and dehydration reactions, as in the case of the retro-aldol pathway and furfural conversion, highlighting the importance of Lewis and Bronsted acid sites in relation to modulating the selectivity of the systems.
Meneghetti, Mario R.,Meneghetti, Simoni M. P.,Pryston, Dhara B. A.,da Silva Avelino, Débora Olimpio,dos Santos, Thatiane V.
(2021/11/16)

Selective oxidation of glycerol over different shaped WO3 supported Pt NPs
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
(2021/04/19)

Kinetics and mechanism of quinolinium dichromate mediated oxidation of sugar alcohols in Bronsted acid media
Bronsted acid catalyzed oxidation of certain sugar alcohols (polyols) has been studied by quinolinium dichromate (QDC) using aqueous sulfuric, perchloric, and hydrochloric acids at different temperatures. At constant acidity, reaction kinetics revealed the second-order kinetics with a first order in [Alcohol] and [QDC]. Zucker-Hammett, Bunnett, and Bunnett-Olsen criteria were used to analyze acid-dependent rate accelerations. Bunnett-Olsen plots of (log k + Hν) versus (Hν + log [H+]), and (log k) versus (Hν + log [H+]) afforded slope values (? and ?*, respectively)?>?0.47, suggesting that a water molecule acts as a prton transfer agent in the slow step of the mechanism in the oxidation of alcohols by QDC in the presence of aqueous sulfuric, perchloric, and hydrochloric acids.
Kodali, Satish Babu,Jakku, Narendar Reddy,Kamatala, Chinna Rajanna,Yerraguntla, Rajeshwar Rao
p. 167 - 177
(2019/12/27)

Selective production of dihydroxyacetone and glyceraldehyde by photo-assisted oxidation of glycerol
Glycerol is a by-product during biodiesel production and represents a potential low-cost raw material for obtaining high-cost products like Dihydroxyacetone (DHA) and glyceraldehyde (GCD) amongst others. In this work, Fe-Pillared clay (Fe-PILC) was assessed as catalyst of the selective photo-oxidation of glycerol to obtain DHA and GCD at moderate conditions (298 K and atmospheric pressure). This was conducted in a 100 mL Pyrex glass batch reactor where a Pen-Ray lamp of mercury of 5.5 W UV light (UVP) was placed at the centre. The Fe-PILC was prepared by ion exchange. The pillaring was confirmed by XRD, and a 17% w/w of Fe was determined by Atomic Absorption Spectroscopy. The active phases were established by XPS and found to be FeO and Fe3O4. The specific surface area of the clay (bentonite), determined by N2 physisorption, increased from 34 m2/g to 227 m2/g and the pore volume increased from 0.058 cm3/g to 0.106 cm3/g. The studied variables were catalyst loading and glycerol initial concentration. An experiment with TiO2 Degussa P25 was also performed as reference. It was found that by adding Fe-PILC to the glycerol oxidation system, selectivity towards DHA or GCD can be tuned. A selectivity towards DHA was found to be 87% with 0.1 g/L of Fe-Pillared after 8 h reaction. The in situ production of H2O2 was observed and therefore concluded that the glycerol oxidation occurs via a fenton process, i.e. via free radicals.
Mendoza, Arisbeht,Romero, Rubí,Gutiérrez-Cedillo, Galilea P.,López-Tellez, Gustavo,Lorenzo-González, Omar,Gómez-Espinosa, Rosa María,Natividad, Reyna
p. 149 - 154
(2020/01/13)

Stanosilicates based on Sn-magadiites applied in conversion of fructose at moderate temperatures
Sn-Magadiite stanosilicates were successfully synthesized by the hydrothermal method. They were found to be efficient in fructose conversion, particularly at 130, 150 and 170 °C. The temperature of 150 °C was ideal for the formation of retro-aldol fragmen
Dos Santos, Tiago Gomes,Da Silva, Antonio Osimar Sousa,Plentz Meneghetti, Simoni Margareti
p. 6111 - 6115
(2020/11/03)

Bi-Functional Magnesium Silicate Catalyzed Glucose and Furfural Transformations to Renewable Chemicals
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
p. 4807 - 4816
(2020/08/24)

Selective Catalytic Dehydrogenative Oxidation of Bio-Polyols to Lactic Acid
The global demand for lactic acid (LA) is increasing due to its successful application as monomer for the manufacture of bioplastics. Although N-heterocyclic carbene (NHC) iridium complexes are promising molecular catalysts for LA synthesis, their instabilities have hindered their utilization especially in commercial applications. Here, we report that a porous self-supported NHC-iridium coordination polymer can efficiently prevent the clusterization of corresponding NHC-Ir molecules and can function as a solid molecular recyclable catalyst for dehydrogenation of bio-polyols to form LA with excellent activity (97 percent) and selectivity (>99 percent). A turnover number of up to 5700 could be achieved in a single batch, due to the synergistic participation of the Ba2+ and hydroxide ions, as well as the blockage of unwanted pathways by adding methanol. Our findings demonstrate a potential route for the industrial production of LA from cheap and abundant bio-polyols, including sorbitol.
Chen, Zhe-Ning,Clark, James H.,Duan, Sai,Liu, Yaoqi,Shen, Lingyun,Sun, Zheming,Tu, Tao,Wu, Jiajie,Xu, Xin,Zheng, Qingshu
supporting information
p. 13871 - 13878
(2020/06/08)

Glycerol Oxidation Catalyzed by High-valency Ruthenium Species at Electrochemical Interfaces
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
supporting information
p. 513 - 516
(2020/05/18)

Tuning product selectivity in the catalytic oxidation of glycerol by employing metal-ZSM-11 materials
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.
supporting information
p. 4363 - 4375
(2020/03/26)

Preparation of AuPd/ZnO-CuO for the directional oxidation of glycerol to DHA
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
p. 6223 - 6234
(2020/10/14)

Atomic-layer-deposited SnO2on Pt/C prevents sintering of Pt nanoparticles and affects the reaction chemistry for the electrocatalytic glycerol oxidation reaction
Atomic layer deposition (ALD) is an efficient technique that allows atomic-level surface control of metal catalysts for the design and development of electrocatalytic materials. Herein, we report a strategy for efficient catalyst design using a particle ALD method to enhance the electrocatalytic glycerol-oxidation-reaction (GOR) performance. Atomically controlled thin SnO2 layers were deposited on a carbon-supported Pt nanoparticle (Pt/C) surface using the ALD technique. The resulting SnO2 overcoated Pt/C (ALD(SnO2)-Pt/C) was then heat-treated at 400 °C under a N2 atmosphere. The onset potential as a kinetic parameter decreased with ALD (SnO2) coatings. The turnover frequency (TOF) for the GOR showed similar values for the tested samples (TOF of Pt/C: 74.86 h-1 and TOF of ALD(SnO2)-Pt/C: 91.29 h-1). Interestingly, interactions between the ALD SnO2 overcoating and Pt nanoparticles improved the catalytic stability for the GOR, preventing sintering of Pt nanoparticle catalysts. This demonstrates that an ALD SnO2 coating on defect sites of Pt can diminish Pt sintering for the GOR. From the GOR in an electrochemical batch reactor, the ALD(SnO2)-Pt/C catalyst also generated more glyceraldehyde (GAD) product than uncoated Pt/C at a similar glycerol conversion level. The density functional theory (DFT) calculations suggest that the binding energies of glycerol and reaction intermediates change at the interface of the SnO2-coated Pt surface compared to those at the Pt surface only, thus affecting the reaction chemistry for the electrocatalytic GOR. This work highlights how we can control reaction performance measures such as catalytic stability and product selectivity by using the particle ALD technique for electrocatalytic reactions such as glycerol oxidation. This journal is
Chang, Hyunju,Chung, Taek-Mo,Han, Hyunsu,Han, Jeong Hwan,Kim, Hyun Woo,Kim, Hyung Ju,Kim, Won Bae,Kim, Youngmin,Lee, Daewon
supporting information
p. 15992 - 16005
(2020/10/02)

Selective Oxidation of Glycerol to Glyceraldehyde with H2O2 Catalyzed by CuNiAl Hydrotalcites Supported BiOCl in Neutral Media
Abstract: CuNiAl hydrotalcites supported BiOCl were prepared by one-step synthesis for the selective oxidation of glycerol to glyceraldehyde with H2O2 as oxidant. The prepared catalysts were found to be efficient due to the synergetic catalysis of surface oxygen vacancies, active Cu2+ ions in the HT-lattice and abundant surface –OH groups of catalysts. The optimal glycerol conversion could reach 75.4% with 82.4% of the selectivity to glyceraldehyde. Moreover, the catalyst could be reused at least 6 times, and a possible reaction mechanism was also proposed. Graphical Abstract: Inexpensive and environmentally friendly BiOCl/CuNiAl-HTs were synthesized by one-step for the highly selective oxidation of glycerol to glyceraldehyde. The glycerol conversion could reach 75.4% with 82.4% selectivity to GLAD. Such a highly efficient catalytic performance could be attributed to the synergistic effect of oxygen vacancies and the coordination of glycerol on Bi3+ in the supported BiOCl catalyst. [Figure not available: see fulltext.].
Wang, Xiaoli,Wu, Gongde,Zhang, Xuelan,Wang, Dengfeng,Lan, Jianyang,Li, Jieyao
p. 1046 - 1056
(2019/02/19)

Glycerol oxidation assisted electrocatalytic nitrogen reduction: Ammonia and glyceraldehyde co-production on bimetallic RhCu ultrathin nanoflake nanoaggregates
As an alternative pathway for present nitrogen fixation methods, the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions represents an attractive approach for sustainable and economic development of chemistry and biology. In this work, we synthesize bimetallic RhCu ultrathin nanoflake nanoaggregates (RhCu-BUNNs) with atomic thickness by a facile hydrothermal method. For the NRR, bimetallic RhCu-BUNNs exhibit better electrocatalytic activity than monometallic Rh ultrathin nanoflake nanoaggregates (Rh-UNNs) because the introduction of Cu can effectively weaken the competitive hydrogen evolution reaction (HER), which can achieve a high NH3 yield rate (95.06 μg h-1 mgcat-1) at -0.2 V potential. Density functional theory (DFT) calculations suggest that the introduction of Cu can effectively lower the energy demand in the ?NN reductive process, resulting in NRR activity enhancement. Meanwhile, RhCu-BUNNs also show excellent electrocatalytic activity and selectivity for the glycerol oxidation reaction (GOR). For the electrochemical NH3 production, the sluggish anodic oxygen evolution reaction (OER) increases the overall electrolysis voltage. Herein, we replace the anodic OER with the GOR to assist the NRR using a bifunctional RhCu-BUNN electrocatalyst. Specifically, only 1.2 V whole voltage is required for electrochemical NH3 production in the presence of glycerol, accompanied by the generation of valuable glyceraldehyde at the anode. This work may provide a promising pathway to obtain both NH3 and valuable organic chemicals with high efficiency and low cost.
Bai, Juan,Huang, Hao,Li, Fu-Min,Zhao, Yue,Chen, Pei,Jin, Pu-Jun,Li, Shu-Ni,Yao, Hong-Chang,Zeng, Jing-Hui,Chen, Yu
p. 21149 - 21156
(2019/10/01)

Method for producing glycolaldehyde
The present invention relates to a method for preparing glycolaldehyde by condensation of formaldehyde. The method uses amidine or immobilized amidine and triazole salt as catalysts, uses alkali as areaction auxiliary agent, and converts formaldehyde to glycolaldehyde, glyceraldehyde and low carbon sugar. The raw material formaldehyde in a reaction system is cheap and easily available, the catalyst synthesis is simple, and a target product glycolaldehyde has a high yield. The production process involved in the present application is simple, easy to operate, and environmentally friendly, and creates favorable conditions for industrial scale production of the product.
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(2019/01/10)

A Polyoxometalate-Based Microfluidic Device for Liquid-Phase Oxidation of Glycerol
Peroxidation of glycerol has been carried out in a polyoxometalate (POM)-based microfluidic reactor, which was fabricated on a capillary by using a layer-by-layer strategy. Lactic acid (LA) is produced selectively in high yield with a TOF as high as 20 000 h?1, compared to a TOF of 200 h?1 in batch mode. This POM microfluidic reactor is readily prepared, scalable, highly stable, reusable, and also potentially applicable to selective oxidation of other bio-wastes.
Tao, Meilin,Li, Yiming,Zhang, Xueyan,Li, Zonghang,Hill, Craig L.,Wang, Xiaohong
p. 2550 - 2553
(2019/06/24)

Aerobic oxidation of glycerol catalyzed by M salts of PMo12O403-(M = K+, Zn2+, Cu2+, Al3+, Cr3+, Fe3+)
Glycerol is a co-product in the manufacture of biodiesel from vegetable oil and animal fat. A significant increase in biodiesel production results in adramatic overproduction of glycerol. The oxidation of glycerol to lactic acid (LA)by O2 is considered to be a promising technology to increase the value of glycerol. Studies on the fundamental reaction mechanism vary for different catalytic systems. In this work we have chosen Keggin polyoxometalates (POMs)as an exemplary family of water-soluble hydrolytically and oxidatively-stable, fully-inorganic complexes with transition-metal and non-transition-metal counter-cations (M in the formula, MPMo12O40, where M = H+, K+, Zn2+, Cu2+, Al3+, Cr3+, Fe3+ in appropriate number to counterbalance the 3- charge of PMo12O403?). Reactions involving hydrogen peroxide, an intermediate during glycerol oxidation, produce free radicals. A kinetic analysis reveals that the radical chain length under typical conditions is about 20–30. After minimal optimization, the yield of LA was 88% at glycerol conversion > 97% (1.0 M aqueous solution of glycerol, 4.0 mM of the Al salt of PMo12O403?, henceforth “AlPMo”, 10 bar O2 at 60 °C, reaction time 6.0 h).
Tao, Meilin,Li, Yiming,Geletii, Yurii V.,Hill, Craig L.,Wang, Xiaohong
p. 52 - 57
(2019/05/01)

Glycerol Partial Oxidation over Pt/Al2O3 Catalysts under Basic and Base-Free Conditions—Effect of the Particle Size
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
p. 63 - 74
(2018/10/26)

Silica-supported chromia-titania catalysts for selective formation of lactic acid from a triose in water
A variety of silica-supported metal oxide catalysts were prepared by the incipient wetness impregnation method and were used for the conversion of dihydroxyacetone to lactic acid. A titanium oxide catalyst with Br?nsted acid sites was selective to an intermediate, pyruvaldehyde and a chromium oxide catalyst with Lewis acid sites was selective to lactic acid. The co-impregnation of chromium- and titanium oxides with different ratios accelerated the reaction rate and improved the lactic acid yield up to 80% at 130 °C. Pyridine-adsorbed Fourier-transform infrared spectroscopy indicated that the silica-supported mixed oxides had both Br?nsted acid and Lewis acid sites and the trend of the Lewis/Br?nsted ratio was close to that of selectivity to lactic acid. Diffuse reflectance UV–vis spectroscopy showed that the silica-supported chromia-titania catalyst composed of isolated Cr and Ti species in tetrahedral coordination. Kinetic analysis revealed that the two critical rate constants, pyruvaldehyde formation and lactic acid formation, for the chromia-titania catalyst were much higher than those of the titania and chromia catalysts.
Takagaki, Atsushi,Goto, Hiroshi,Kikuchi, Ryuji,Oyama, S. Ted
p. 200 - 208
(2018/12/02)

Method for catalytic synthesis for glyceraldehyde acetonide
The invention relates to a method for catalytic synthesis for glyceraldehyde acetonide. The method specifically comprises the following steps: dissolving glycerol acetonide into acetone, adding a proper amount of a fullerene zinc oxide selenium (C60/ZnO/Se) composite material, introducing oxygen to carry out a reaction at a room temperature till a reaction liquid has no glycerol acetonide, centrifuging to remove the fullerene zinc oxide selenium (C60/ZnO/Se) composite material, carrying out vacuum concentration on supernate, and drying to obtain the glyceraldehyde acetonide.
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Paragraph 0048-0053

(2018/11/22)

Dinuclear Manganese(II), Cobalt(II), and Nickel(II) Aryl Phosphates Incorporating 4′-Chloro-2,2′:6′,2′′-Terpyridine Coligands – Efficient Catalysts for Alcohol Oxidation
The dinuclear cyclo(metallo)phosphates [M(dipp)(Cl-terpy)]2 [M = Mn (1), Ni (2)] and the mononuclear cobalt phosphate [Co(dippH)(Cl-terpy)(MeOH)(H2O)]·dippH (3) were synthesized through the reactions of 4′-chloro-2,2′:6′,2′′-terpyridine (Cl-terpy) and 2,6-diisopropylphenyl phosphate (dippH2) with manganese, nickel, and cobalt acetates. The formation of 1–3 is supported by spectroscopic, thermogravimetric, and microanalytical data. The molecular structures of 1 and 3 were confirmed by single-crystal X-ray diffraction studies. Compounds 1 and 2 are dimeric and feature two octahedral metal centers bridged by dianionic dipp ligands. On the other hand, 3 exists as a monomer in the solid state, but dissolution in methanol converts it to a dimeric form similar to those of 1 and 2, as evidenced by ESI-MS studies. Compounds 1–3 were employed as catalysts for alcohol oxidation reactions with tert-butyl hydroperoxide (TBHP) as the oxidant. The manganese phosphate 1 exhibits better catalytic activity in terms of selectivity and substrate conversion compared with those of 2 and 3 under similar conditions.
Bhat, Gulzar A.,Rajendran, Antony,Murugavel, Ramaswamy
p. 795 - 804
(2018/02/21)

Polydentate 4-Pyridyl-terpyridine Containing Discrete Cobalt Phosphonate and Polymeric Cobalt Phosphate as Catalysts for Alcohol Oxidation
Mononuclear discrete cobalt phosphonate [Co(pytpy)(tBuPO3H)2(H2O)]·H2O (1) and 1D zigzag polymeric cobalt phosphate [Co(pytpy)2(dipp)(MeOH)·2MeOH]n (2) were prepared from the reactions of tert-butyl phosphonic acid (tBuPO3H2) and organic-soluble 2,6-diisopropylphenyl phosphate (dippH2) ligands with Co(OAc)2·4H2O in the presence of 4′-pyridyl 2,2′:6′,2′′-terpyridine in MeOH/CHCl3(1:1 v/v) solvent mixture at 25 °C. The new compounds were characterized by analytical, thermo-analytical, and spectroscopic techniques. Further, the molecular structures were established by single-crystal X-ray diffraction studies. Mass spectrometry analysis reveal that both the compounds exist in the solution phase as dimers. Compound 1 was employed as homogeneous catalysts for alcohol oxidation reactions using tert-butyl hydroperoxide (TBHP) as the oxidant.
Bhat, Gulzar A.,Rajendran, Antony,Murugavel, Ramaswamy
p. 692 - 699
(2018/08/06)

Deactivation and regeneration of: In situ formed bismuth-promoted platinum catalyst for the selective oxidation of glycerol to dihydroxyacetone
Glycerol oxidation over a Pt catalyst can be effectively enhanced by a Bi additive in terms of activity and 1,3-dihydroxyacetone (DHA) selectivity. However, this catalyst system can suffer from serious deactivation. Here, a Bi-promoted Pt catalyst was developed to selectively produce DHA by maintaining the glycerol solution with Bi(NO3)3·5H2O to meet the continuous operation of practical applications. The catalyst deactivation mechanism was investigated in terms of leaching, over-oxidation, agglomeration and poisoning. It was ascertained that the catalyst deactivation was due to the adsorption of chelating intermediates on the catalyst surfaces. A regeneration method by post-heat-treatment at 200-300 °C could remove the intermediates and regenerate the catalyst, allowing recycling for at least 5 runs without clear catalyst deactivation.
Ning, Xiaomei,Zhan, Liang,Wang, Hongjuan,Yu, Hao,Peng, Feng
p. 18837 - 18843
(2018/11/27)

Unraveling the mechanism of the oxidation of glycerol to dicarboxylic acids over a sonochemically synthesized copper oxide catalyst
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
supporting information
p. 2730 - 2741
(2018/06/29)

Transformation of cellulose and related carbohydrates into lactic acid with bifunctional Al(III)-Sn(II) catalysts
The catalytic transformation of cellulose into valuable chemicals such as lactic acid under mild conditions represents a promising route for the efficient utilization of renewable biomass. Here, we report that the combination of Al(iii) and Sn(ii) cations can efficiently catalyse the conversion of cellulose and related carbohydrates into lactic acid in water. Al(iii)-Sn(ii) is the most efficient combination for lactic acid formation among the many dual cations investigated. Al(iii) and Sn(ii) with a molar ratio of 1/1 work cooperatively, providing lactic acid with yields of 90%, 81% and 65% in the conversions of fructose, glucose and cellulose, respectively. The formation of lactic acid involves a series of tandem steps including the hydrolysis of cellulose to glucose, the isomerisation of glucose to fructose, the retro-aldol fragmentation of fructose to C3 intermediates and the subsequent conversion of the C3 intermediates to lactic acid. Our experimental and computational studies suggest that Al(iii) mainly catalyses the isomerisation of glucose or the C3 intermediates, whereas Sn(ii) is primarily responsible for the retro-aldol fragmentation. The combination of the two cations enables the reaction to proceed smoothly with few side reactions, providing outstanding catalytic performances for lactic acid production from cellulose or the related carbohydrates.
Deng, Weiping,Wang, Pan,Wang, Binju,Wang, Yanliang,Yan, Longfei,Li, Yanyun,Zhang, Qinghong,Cao, Zexing,Wang, Ye
supporting information
p. 735 - 744
(2018/02/14)

A comparison of entrapped and covalently bonded laccase: Study of its leakage, reusability, and the catalytic efficiency in TEMPO-mediated glycerol oxidation
This article presents the comparison for reusability and leakage between entrapped and covalently bonded laccase and their performances towards the selective oxidation of glycerol. The reusability of immobilized laccase enzyme was studied by reacting a batch of immobilized laccase with ABTS for 15 cycles. The investigation of the leakage of immobilized laccase was carried out by storing the immobilized laccase in acetate buffer solution for 32 days. The data show that the retained enzyme activities of entrapped and covalently bonded enzyme after being reused for eight cycles were well above 60% and the leakages after storing for a month in the acetate buffer at 4 °C were well below 15%. The entrapped laccase coupled with TEMPO was found to perform better and gave a two-fold higher yield of glyceraldehyde and glyceric acid in the selective oxidation of glycerol compared to covalently bonded laccase. Hence, physical entrapment of laccase would be a suitable immobilization method in the laccase-mediated selective oxidation of glycerol.
Hong, Chi Shein,Lau, Cindy Chin Yee,Leong, Chun Yi,Chua, Gek Kee,Chin, Sim Yee
p. 352 - 361
(2017/10/23)

One-pot synthesis of 2-hydroxymethyl-5-methylpyrazine from renewable 1,3-dihydroxyacetone
An efficient and green method for the synthesis of 2-hydroxymethyl-5-methylpyrazine was achieved from biomass derived 1,3-dihydroxyacetone and diammonium phosphate via a one-pot reaction. The product yield was as high as 72% under optimized conditions of pH = 8.0-9.1 at 90 °C for 1 hour in a dioxane and water mixture as a solvent. A possible reaction mechanism was proposed according to the reaction kinetics, NMR and in situ ATR-IR characterization studies.
Song, Lei,Zheng, Mingyuan,Pang, Jifeng,Sebastian, Joby,Wang, Wentao,Qu, Minjie,Zhao, Jian,Wang, Xinhong,Zhang, Tao
supporting information
p. 3515 - 3519
(2017/08/15)

PRODUCTION OF ALPHA-HYDROXY CARBOXYLIC AIDS AND ESTERS FROM HIGHER SUGARS USING TANDEM CATALYST SYSTEMS
The present disclosure is directed to methods and composition used in the preparation of alpha-hydroxy carboxylic acids and esters from higher sugars using a tandem catalyst system comprising retro-aldol catalysts and Lewis acid catalysts. In some embodiments, these alpha-hydroxy carboxylic acids may be prepared from pentoses and hexoses. The retro-aldol and Lewis catalysts may be characterized by their respective ability to catalyze a 1,2-carbon shift reaction and a 1,2-hydride shift reaction on an aldose or ketose substrate.
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Page/Page column 2; 13-14

(2017/02/09)

Keggin heteropolyacids supported on TiO2 used in gas-solid (photo)catalytic propene hydration and in liquid-solid photocatalytic glycerol dehydration
(Photo)catalytic propene hydration to 2-propanol and glycerol dehydration to acrolein were carried out by using Keggin heteropolyacids (HPAs) supported on TiO2. Binary materials have been prepared by impregnation of H3PW12O40, H3PMo12O40 and H4SiW12O40, on TiO2 Evonik P25. Moreover, a binary material consisting of H4SiW12O40 and TiO2 was prepared via a hydrothermal treatment and tested for the same reactions. All the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy observations (SEM) coupled with energy dispersive X-ray (EDX) measurements, diffuse reflectance spectroscopy (DRS), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). The supported Keggin HPA species played a key role both for the catalytic and for the photo-assisted catalytic reactions due to their strong acidity and ability to form strong oxidant species under UV irradiation.
Marcì, Giuseppe,García-López, Elisa,Vaiano, Vincenzo,Sarno, Giuseppe,Sannino, Diana,Palmisano, Leonardo
p. 60 - 70
(2016/11/30)

Kinetic study of the ethyl lactate synthesis from triose sugars on Sn/Al2O3 catalysts
The reaction kinetics of the liquid-phase synthesis of ethyl lactate from dihydroxyacetone and ethanol was studied on Sn-promoted alumina catalysts. Yields of ≈70% were obtained at 353?K after 7?h of reaction. The effect of the catalyst Sn loading (1–8?wt.%) and reaction temperature (343–373?K) on the reaction kinetics was investigated. The reaction is promoted by Lewis acid sites provided by surface Sn species. A kinetic model based on a pseudohomogeneous mechanism was postulated to describe the reaction network comprising a sequence of consecutive and parallel reaction steps. The kinetic rate constant associated to ethyl lactate formation increases with the number of Lewis acid sites confirming that surface Sn species participate in the kinetically relevant reaction steps. Catalysts were prepared by impregnation and characterized by N2 physisorption, X-ray diffraction, UV-vis-DRS, FTIR of pyridine and TPD of NH3.
Pighin,Díez,Di Cosimo
p. 29 - 37
(2017/05/16)

Prebiotic synthesis of aminooxazoline-5′-phosphates in water by oxidative phosphorylation
RNA is essential to all life on Earth and is the leading candidate for the first biopolymer of life. Aminooxazolines have recently emerged as key prebiotic ribonucleotide precursors, and here we develop a novel strategy for aminooxazoline-5′-phosphate synthesis in water from prebiotic feedstocks. Oxidation of acrolein delivers glycidaldehyde (90%), which directs a regioselective phosphorylation in water and specifically affords 5′-phosphorylated nucleotide precursors in upto 36% yield. We also demonstrated a generational link between proteinogenic amino acids (Met, Glu, Gln) and nucleotide synthesis.
Fernández-García,Grefenstette,Powner
supporting information
p. 4919 - 4921
(2017/07/11)

Making H2 from light and biomass-derived alcohols: The outstanding activity of newly designed hierarchical MWCNT/Pd@TiO2 hybrid catalysts
Hydrogen evolution is among the most investigated catalytic processes given the importance of H2 from an industrial and an energy perspective. Achieving H2 production through green routes, such as water splitting or more realistically photoreforming of alcohols, is particularly desirable. In this work, we achieve a remarkable H2 productivity through photoreforming of either ethanol or glycerol as a sacrificial electron donor by employing a hybrid nanocatalyst where the properties of multi-walled carbon nanotubes (MWCNTs), Pd nanoparticles and crystalline TiO2 are optimally merged through appropriate engineering of the three components and an optimised synthetic protocol. Catalysts were very active both under UV (highest activity 25 mmol g-1 h-1) and simulated solar light (1.5 mmol h-1 g-1), as well as very stable. Critical to such high performance is the intimate contact of the three phases, each fulfilling a specific task synergistically with the other components.
Beltram,Melchionna,Montini,Nasi,Fornasiero,Prato
supporting information
p. 2379 - 2389
(2017/07/15)

Prebiotic synthesis of phosphoenol pyruvate by α-phosphorylation-controlled triose glycolysis
Phosphoenol pyruvate is the highest-energy phosphate found in living organisms and is one of the most versatile molecules in metabolism. Consequently, it is an essential intermediate in a wide variety of biochemical pathways, including carbon fixation, the shikimate pathway, substrate-level phosphorylation, gluconeogenesis and glycolysis. Triose glycolysis (generation of ATP from glyceraldehyde 3-phosphate via phosphoenol pyruvate) is among the most central and highly conserved pathways in metabolism. Here, we demonstrate the efficient and robust synthesis of phosphoenol pyruvate from prebiotic nucleotide precursors, glycolaldehyde and glyceraldehyde. Furthermore, phosphoenol pyruvate is derived within an α-phosphorylation controlled reaction network that gives access to glyceric acid 2-phosphate, glyceric acid 3-phosphate, phosphoserine and pyruvate. Our results demonstrate that the key components of a core metabolic pathway central to energy transduction and amino acid, sugar, nucleotide and lipid biosyntheses can be reconstituted in high yield under mild, prebiotically plausible conditions.
Coggins, Adam J.,Powner, Matthew W.
p. 310 - 317
(2017/04/03)

Selective oxidation of glycerol in base-free conditions over N-doped carbon film coated carbon supported Pt catalysts
A series of N-doped carbon film coated active carbon (NxC-XC-72) was prepared via direct pyrolysis of mixed XC-72 (a commercial activated carbon), polyvinyl pyrrolidone and urea. Characterizations indicated that the specific area of synthesized N2.5C-XC-72 reached 281 m2/g and uniform meso pore channels (sized in 4.0 nm) formed. It was found that NxC-XC-72 was an excellent support for the evenly dispersion of Pt compared with raw XC-72. Pt/NxC-XC-72 was active and stable for the selective oxidation of glycerol to glyceric acid in a base-free aqueous solution. The calculated turnover frequency on the basis of surface Pt increased from 573 (in Pt/XC-72) to 706 h? 1 (in Pt/N2.5C-XC-72) at 60 °C.
Yang, Lihua,Li, Xuewen,Sun, Yanyan,Yue, Linhai,Fu, Jie,Lu, Xiuyang,Hou, Zhaoyin
p. 107 - 110
(2017/08/14)

Characterization of methylated azopyridine as a potential electron transfer mediator for electroenzymatic systems
N,N'-dimethyl-4,4'-azopyridinium methyl sulfate (MAZP) was characterized as an electron transfer mediator for oxidation reactions catalyzed by NAD+- and pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenases. The bimolecular rate constant of NADH reactivity with MAZP was defined as (2.2?±?0.1)?×?105?M?1?s?1, whereas the bimolecular rate constant of reactivity of the reduced form of PQQ-dependent alcohol dehydrogenase with MAZP was determined to be (4.7?±?0.1)?×?104?M?1?s?1. The use of MAZP for the regeneration of the cofactors was investigated by applying the electrochemical oxidation of the mediator. The total turnover numbers of mediator MAZP and cofactor NADH for ethanol oxidation catalyzed by NAD+-dependent alcohol dehydrogenase depended on the concentration of the substrate and the duration of the electrolysis, and the yield of the reaction was limited by the enzyme inactivation and the electrochemical process. The PQQ-dependent alcohol dehydrogenase was more stable, and the turnover number of the enzyme reached a value of 2.3?×?103. In addition, oxidation of 1,2-propanediol catalyzed by the PQQ-dependent alcohol dehydrogenase proceeded enantioselectively to yield L-lactic acid.
Tetianec, Lidija,Chaleckaja, Ana,Kulys, Juozas,Janciene, Regina,Marcinkeviciene, Liucija,Meskiene, Rita,Stankeviciute, Jonita,Meskys, Rolandas
p. 41 - 48
(2017/06/05)

The Role of Ruthenium on Carbon-Supported PtRu Catalysts for Electrocatalytic Glycerol Oxidation under Acidic Conditions
A series of binary PtRu catalysts with different Pt/Ru atomic ratios (from 7:3 to 3:7) were synthesized on a carbon support using the colloidal method; they were then used for electrooxidation of glycerol in acid media. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy analyses were used to investigate particle size, size distribution, and structural and electronic properties of the prepared catalysts. Ru added to the Pt-based catalysts caused structural and electronic modifications over the PtRu alloy catalyst formation. The electrocatalytic activities of PtRu/C series catalysts were investigated using cyclic voltammetry. The Pt5Ru5/C catalyst shows enhanced catalytic activity at least 40 % higher than that of the Pt/C catalyst, with improved stability for glycerol electrooxidation; these improvements are attributed to structural and electronic modifications of the Pt catalysts. Using an electrocatalytic batch reactor, product analysis after the oxidation reaction was performed by high-performance liquid chromatography to determine and compare the reaction pathways on the Pt/C and PtRu/C catalysts. To understand different catalytic activities of glycerol oxidation on the PtRu alloy surfaces, density functional calculations were performed.
Kim, Youngmin,Kim, Hyun Woo,Lee, Seonhwa,Han, Jisu,Lee, Daewon,Kim, Jeong-Rang,Kim, Tae-Wan,Kim, Chul-Ung,Jeong, Soon-Yong,Chae, Ho-Jeong,Kim, Beom-Sik,Chang, Hyunju,Kim, Won Bae,Choi, Sung Mook,Kim, Hyung Ju
p. 1683 - 1690
(2017/05/15)

Catalytic routes and oxidation mechanisms in photoreforming of polyols
Photocatalytic reforming of biomass-derived oxygenates leads to H2 generation and evolution of CO2 via parallel formation of organic intermediates through anodic oxidations on a Rh/TiO2 photocatalyst. The reaction pathways and kinetics in the photoreforming of C3–C6 polyols were explored. Polyols are converted via direct and indirect hole transfer pathways resulting in (i) oxidative rupture of C–C bonds, (ii) oxidation to α-oxygen functionalized aldoses and ketoses (carbonyl group formation) and (iii) light-driven dehydration. Direct hole transfer to chemisorbed oxygenates on terminal Ti(IV)-OH groups, generating alkoxy-radicals that undergo ?-C–C-cleavage, is proposed for the oxidative C–C rupture. Carbonyl group formation and dehydration are attributed to indirect hole transfer at surface lattice oxygen sites [Ti?O?Ti] followed by the generation of carbon-centered radicals. Polyol chain length impacts the contribution of the oxidation mechanisms favoring the C–C bond cleavage (internal preferred over terminal) as the dominant pathway with higher polyol carbon number.
Sanwald, Kai E.,Berto, Tobias F.,Eisenreich, Wolfgang,Gutiérrez, Oliver Y.,Lercher, Johannes A.
p. 806 - 816
(2016/12/09)

Nanoscale Pd-based catalysts for selective oxidation of glycerol with molecular oxygen: Structure–activity correlations
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.
p. 124 - 133
(2016/12/06)

Zeolite-supported iron catalysts for allyl alcohol synthesis from glycerol
Under most reaction conditions studied, acrolein is reported as the primary product in the conversion of glycerol over zeolites. In such processes, acrolein forms at relatively high yields, with negligible allyl alcohol selectivity. In this contribution, we report the development of ZSM5-supported iron catalysts, modified by rubidium deposition, as stable materials for production of allyl alcohol from glycerol. Our results demonstrate a reduced rate of formation of acrolein over modified catalysts. Both unmodified and modified catalysts were analysed by inductively coupled plasma optical emission spectrometry, nitrogen adsorption, scanning electron microscope, X-ray diffraction, ammonia temperature programmed desorption, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. These techniques revealed that differences in product distribution and catalyst performance are due to the combined effects of iron loading, catalyst acidity and changes in the porosity of the catalyst.
Sánchez,Dlugogorski,Kennedy,Stockenhuber
p. 130 - 142
(2015/11/24)

PROCESS FOR THE CONVERSION OF SUGARS TO LACTIC ACID AND 2-HYDROXY-3-BUTENOIC ACID OR ESTERS THEREOF COMPRISING A METALLO-SILICATE MATERIAL AND A METAL ION
The present invention regards metallo-silicate materials comprising a metal ion selected from one or more of the group consisting of potassium ions, sodium ions, lithium ions, rubidium ions and caesium ions. The materials are useful preparing lactic acid and 2-hydroxy-3-butenoic acid or esters thereof from a sugar.
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Paragraph 0054; 0055; 0056; 0057; 0058

(2017/03/21)

Effect of electron acceptors H2O2 and O2 on the generated reactive oxygen species 1O2 and OH in TiO2-catalyzed photocatalytic oxidation of glycerol
The effect of the electron acceptors H2O2 and O2 on the type of generated reactive oxygen species (ROS), and glycerol conversion and product distribution in the TiO2-catalyzed photocatalytic oxidation of glycerol was studied at ambient conditions. In the absence of an electron acceptor, only HO radicals were generated by irradiated UV light and TiO2. However, in the presence of the two electron acceptors, both HO radical and 1O2 were produced by irradiated UV light and TiO2 in different concentrations that depended on the concentration of the electron acceptor. The use of H2O2 as an electron acceptor enhanced glycerol conversion more than O2. The type of generated value-added compounds depended on the concentration of the generated ROS.
Jedsukontorn, Trin,Meeyoo, Vissanu,Saito, Nagahiro,Hunsom, Mali
p. 1975 - 1981
(2016/12/09)

Combined EC-NMR and in Situ FTIR Spectroscopic Studies of Glycerol Electrooxidation on Pt/C, PtRu/C, and PtRh/C
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
p. 7686 - 7695
(2016/11/17)

Hydrolysis behaviors of sugarcane bagasse pith in subcritical carbon dioxide-water
The aim of this study was to describe the hydrolysis behavior of sugarcane bagasse pith (SCBP) in subcritical CO2-water. The hydrolysis was carried out in a batch reactor using different temperatures (160 to 260 °C), liquid to solid ratios (20:1 to 100:1), CO2 pressures (0 to 7.3 MPa), stirring speeds (0 to 500 rpm) and reaction times (0 to 40 min). The highest total reducing sugar yield (43.6%) was obtained at 200 °C, liquid to solid ratio 30:1, 2 MPa CO2, 500 rpm and 50 min. Two-dimensional heteronuclear single quantum coherence (2D HSQC) nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FT-IR) were used to help elucidate the physical and chemical characteristics of the raw material and residual solid particles, with results consistent with the removal of hemicellulose during hydrolysis. The changes in the concentration of products with time were analyzed to understand product distribution through high-performance liquid chromatography (HPLC) and to infer the reaction mechanism.
Liang, Jiezhen,Chen, Xiaopeng,Wang, Linlin,Wei, Xiaojie,Qiu, Feifei,Lu, Chaochao
p. 99322 - 99330
(2016/11/02)