- Effects of Alkali-Metal Ions and Counter Ions in Sn-Beta-Catalyzed Carbohydrate Conversion
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Alkali-metal ions have recently been shown to strongly influence the catalytic behavior of stannosilicates in the conversion of carbohydrates. An effect of having alkali-metal ions present is a pronounced increase in selectivity towards methyl lactate. Mechanistic details of this effect have remained obscure and are herein addressed experimentally through kinetic experiments and isotope tracking. The presence of alkali-metal ions has a differential effect in competing reaction pathways and promotes the rate of carbon–carbon bond breakage of carbohydrate substrates, but decreases the rates of competing dehydration pathways. Further addition of alkali-metal ions inhibits the activity of Sn-Beta in all major reaction pathways. The alkali-metal effects on product distribution and on the rate of product formation are similar, thus pointing to a kinetic reaction control and to irreversible reaction steps in the main pathways. Additionally, an effect of the accompanying basic anions is shown, supposedly facilitating the cation exchange and eliciting a different concentration-dependent effect to that of neutral alkali-metal salts.
- Elliot, Samuel G.,Tolborg, S?ren,Madsen, Robert,Taarning, Esben,Meier, Sebastian
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- Development of bimetallic Ni-Cu/SiO2 catalysts for liquid phase selective hydrogenation of furfural to furfuryl alcohol
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Bimetallic Ni-Cu/SiO2 catalysts with different Cu loading (2–5 wt%) were developed for liquid phase selective hydrogenation of furfural to furfuryl alcohol. Among these, bimetallic 2%Ni-X%Cu/SiO2 (X = 2, 5) catalysts exhibited better
- Weerachawanasak, Patcharaporn,Krawmanee, Pacharaporn,Inkamhaeng, Weerachat,Cadete Santos Aires, Francisco J.,Sooknoi, Tawan,Panpranot, Joongjai
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- Oxidative esterification of furfural by Au nanoparticles supported CMK-3 mesoporous catalysts
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Furfural which is derived from the hemicellulose fraction of abundant lignocellulose has received significant attention to many researchers as its valorization yields useful products such as fine chemicals and transportation fuels. Methyl 2-furoate is one
- Radhakrishnan, Ramakrishnan,Thiripuranthagan, Sivakumar,Devarajan, Arulselvan,Kumaravel, Sakthivel,Erusappan, Elangovan,Kannan, Kathiravan
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- Flame spray-synthesized Pt-Co/TiO2 catalysts for the selective hydrogenation of furfural to furfuryl alcohol
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Flame spray-synthesized Pt/TiO2 and PtCo/TiO2 catalysts with 0.7 wt% Pt and 0–0.4 wt% Co were studied in the hydrogenation of furfural to furfuryl alcohol (FA) at 50 °C and 2 MPa H2. Particle formation under high temperatu
- Cadete Santos Aires, Francisco José,Khruechao, Kitima,Mekasuwandumrong, Okorn,Panpranot, Joongjai,Pongthawornsakun, Boontida,Tolek, Weerachon,Weerachawanasak, Patcharaporn
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- A regulatable oxidative valorization of furfural with aliphatic alcohols catalyzed by functionalized metal-organic frameworks-supported Au nanoparticles
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The oxidative upgrading of furfural (FUR) and aliphatic alcohols is an important way to produce desirable precursor of jet fuel or value-added furanic compound. Therein, developing a highly active catalytic system with switchable product selectivity still remains a challenge. In this work, we report a novel strategy on regulating the oxidative condensation and oxidative esterification of FUR with aliphatic alcohol in the presence of molecular oxygen. Firstly, Au@UiO-66 is prepared using different methods and employed as the catalyst for the oxidative valorization of FUR with methanol. It is found that the impregnation-reduction-H2 (I-H) method is the best where a 100% selectivity of methyl-2-furoate with a complete conversion was obtained using Au@UiO-66 as catalyst. Then, a series of metal-organic frameworks (MOFs) supported Au nanoparticles (Au@UiO-66-X) such as Au@UiO-66, Au@UiO-66-NH2, Au@UiO-66-NO2, Au@UiO-66-COOH and Au@UiO-66-NH3Cl have been prepared with I-H method and employed for oxidative valorization of furfural with ethanol. Experimental results showed that, in “FUR-ethanol-O2” system, the Au@UiO-66-X can efficiently regulate the oxidative condensation and oxidative esterification as two competitive reaction pathways. With Au@UiO-66-COOH as the catalyst, the oxidative condensation process is dominant in which 84.1% selectivity of furan-2-acrolein is attained; Meanwhile, the Au@UiO-66 is beneficial to the occurrence of oxidative esterification and generation of ethyl-2-furoate. At last, based on the catalyst characterization and the numerous control experiments, a possible catalytic reaction mechanism for conversion of FUR is proposed.
- Ning, Liangmin,Liao, Shengyun,Liu, Xuguang,Guo, Pengfei,Zhang, Zhenya,Zhang, Haigang,Tong, Xinli
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- Synthesis of a novel polyester building block from pentoses by tin-containing silicates
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We report here the direct formation of the new chemical product trans-2,5-dihydroxy-3-pentenoic acid methyl ester from pentoses using tin-containing silicates as catalysts. The product is formed under alkali-free conditions in methanol at temperatures in the range 140-180 °C. The highest yields are found using Sn-Beta as the catalyst. Under optimised conditions, a yield of 33% is achieved. Purified trans-2,5-dihydroxy-3-pentenoic acid methyl ester was used for co-polymerisation studies with ethyl 6-hydroxyhexanoate using Candida antarctica lipase B as the catalyst. The co-polymerisation yields a product containing functional groups originating from trans-2,5-dihydroxy-3-pentenoic acid methyl ester in the polyester backbone. The reactivity of the incorporated olefin and hydroxyl moieties was investigated using trifluoroacetic anhydride and thiol-ene chemistry, thus illustrating the potential for functionalising the new co-polymers.
- Elliot,Andersen,Tolborg,Meier,Sádaba,Daugaard,Taarning
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p. 985 - 996
(2017/01/13)
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- Selective, aerobic oxidation reaction of alcohols by hybrid Pd/ZrO2/PVA catalytic membranes
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Palladium nanoparticles of 2.1 ± 0.9 nm size were generated within a hybrid zirconia/polyvinyl alcohol membrane of 60 ± 5 μm thickness, to afford a bulk 6.7% Pd loading (w/w). The material was used as catalyst for the heterogeneous, batch and continuous flow partial oxidation reaction of functionalized alcohols, using air or oxygen as oxidants and water or methanol as solvents. Good selectivity to the corresponding aldehydes at full conversion and excellent resistance over prolonged time-on-stream under very mild reaction conditions was observed. No metal leaching in solution was detected, as well as no additives nor regeneration steps were needed.
- Liguori, Francesca,Moreno-Marrodan, Carmen,Barbaro, Pierluigi,Sawa, Haruo
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p. 217 - 225
(2016/12/14)
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- Oxidative esterification of renewable furfural on gold-based catalysts: Which is the best support?
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Gold-based catalysts over different supports were investigated in the oxidative esterification of furfural by employing an efficient and sustainable process. The catalytic performances follow the trend: Zirconia-Au > Ceria-Au a‰
- Menegazzo, Federica,Signoretto, Michela,Pinna, Francesco,Manzoli, Maela,Aina, Valentina,Cerrato, Giuseppina,Boccuzzi, Flora
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p. 241 - 247
(2013/12/04)
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- Sn-Beta catalysed conversion of hemicellulosic sugars
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Conversions of various pentoses and hexoses into methyl lactate has been demonstrated for the Sn-Beta catalyst. It is found that pentoses are converted to methyl lactate in slightly lower yields (~40%) than what is obtained for hexoses (~50%), but higher yields of glycolaldehyde dimethyl acetal are observed for the pentoses. This finding is in accordance to a reaction pathway that involves the retro aldol condensation of the sugars to form a triose and glycolaldehyde for the pentoses, and two trioses for hexoses. When reacting glycolaldehyde (formally a C2-sugar) in the presence of Sn-Beta, aldol condensation occurs, leading to the formation of methyl lactate, methyl vinylglycolate and methyl 2-hydroxy-4-methoxybutanoate. In contrast, when converting the sugars in water at low temperatures (100 °C), Sn-Beta catalyses the isomerisation of sugars (ketose-aldose epimers), rather than the formation of lactates. The Royal Society of Chemistry 2012.
- Holm, Martin S.,Pagan-Torres, Yomaira J.,Saravanamurugan, Shunmugavel,Riisager, Anders,Dumesic, James A.,Taarning, Esben
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experimental part
p. 702 - 706
(2012/04/23)
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- Acid-catalyzed conversion of xylose in methanol-rich medium as part of biorefinery
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Acid treatments of xylose have been performed in a methanol/water mixture to investigate the reaction pathways of xylose during bio-oil esterification. Xylose was mainly converted into methyl xylosides with negligible humins formed below 130°C. However, humins formation became significant with the dehydration of xylose to furfural and 2-(dimethoxymethyl)furan (DOF) at elevated temperatures. The conversion of xylose to methyl xylosides protected the C1 hydroxyl group of xylose, which stabilized xylose and suppressed the formation of sugar oligomers and polymerization reactions. In comparison, the conversion of furfural to DOF protected the carbonyl group of furfural. However, the protection did not remarkably suppress the polymerization of furfural at high temperatures because of the shift of the reaction equilibrium from DOF to furfural with a prolonged residence time. In addition, the acid treatment of furfural produced methyl levulinate in methanol and levulinic acid in water, which was catalyzed by formic acid. Copyright
- Hu, Xun,Lievens, Caroline,Li, Chun-Zhu
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experimental part
p. 1427 - 1434
(2012/10/08)
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