6018-27-5Relevant articles and documents
Effect of Cu addition to carbon-supported Ru catalysts on hydrogenation of alginic acid into sugar alcohols
Ban, Chunghyeon,Yang, Seungdo,Kim, Hyungjoo,Kim, Do Heui
, p. 98 - 104 (2019/04/17)
The objective of this study was to investigate the effect of Cu addition to carbon supported Ru catalysts on the hydrogenation of macroalgae-derived alginic acid into sugar alcohols, mainly sorbitol and mannitol. Both geometric and electronic effects were determined based on results of H2-TPR, H2- or CO-chemisorption, and XPS analyses after Cu was added to Ru. The addition of Cu to Ru caused blocking of active Ru surface and electron transfer between Ru and Cu. The intimate interaction between Ru and Cu formed RuCu bimetallic clusters which expedited hydrogen spillover from Ru to Cu. The highest yield of target sugar alcohols of 47.4% was obtained when 5 wt% of Ru and 1 wt% of Cu supported on nitric acid-treated activated carbon reacted at 180 °C for 2 h. The RuCu bimetallic catalyst exhibited deactivation upon repeated reactions due to the carbon deposition on the catalyst.
Preparation method of gamma-acetyl n-propanol
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Paragraph 0036; 0037, (2017/12/09)
The invention discloses a preparation method of gamma-acetyl n-propanol. The method includes the steps of (1) adding the hydrolysate of plant fiber or xylose and other raw materials into a reaction still, adding a two-phase reactive solvent and a catalyst, inletting hydrogen, and heating the reaction still to react for several hours; (2) carrying out standing, liquid separation and then solid-liquid separation on reaction materials in the reaction still, obtaining water phase, oil phase and the catalyst, and recycling the catalyst for reutilization; (3) concentrating water phase products, extracting 1, 4-pentanediol in the oil phase, mixing with the concentrated solution, and carrying out further separation to obtain a crude product of 1, 4-pentanediol; (4) pumping the crude product of 1, 4-pentanediol obtained from the water phase and the oil phase in step (3) to a fixed bed reactor, carrying out dehydrogenation to produce gamma-acetyl n-propanol under the action of a catalytic dehydrogenation catalyst or an oxydehydrogenation catalyst. According to the preparation method, raw materials have extensive sources, the production cost is low, no inorganic acid system is used, and the reaction process is environment-friendly.
CTAB-assisted sol-microwave method for fast synthesis of mesoporous TiO2 photocatalysts for photocatalytic conversion of glucose to value-added sugars
Payormhorm, Jiraporn,Chuangchote, Surawut,Laosiripojana, Navadol
, p. 546 - 555 (2017/09/01)
Fabrication technique is an important factor for development of catalysts. Titanium dioxide (TiO2) is one of efficient photocatalysts. In this work, we firstly report the fabrication of TiO2 nanoparticles by sol-microwave method with cetyltrimethylammonium bromide (CTAB) surfactant. Absence of surfactant, microwave treatment significantly reduced the cluster sizes of TiO2, but high aggregations of TiO2 particles were observed. CTAB has great impact on morphology, cluster size and mesoporous structure of TiO2. Therefore, surface area of TiO2 synthesized by sol-microwave method with 0.108 M CTAB increased from 15.97 to 37.60 m2/g. Photocatalytic activity of TiO2 was tested via the glucose conversion to produce value-added chemicals (gluconic acid, xylitol, arabinose and formic acid). It was found that surface area, mesoporous structure and pore size of TiO2 are crucial properties for glucose conversion and product distribution. From the reaction test, 0.108 M CTAB/MW-TiO2 achieved the highest glucose conversion (62.28%).
Selective hydrogenolysis of biomass-derived xylitol to ethylene glycol and propylene glycol on supported Ru catalysts
Sun, Jiying,Liu, Haichao
experimental part, p. 135 - 142 (2011/04/15)
The selective hydrogenolysis of biomass-derived xylitol to ethylene glycol and propylene glycol was carried out on different catalysts in the presence of Ca(OH)2. The catalysts included Ru supported on activated carbon (C) and, for comparison, on metal oxides, Al2O3, TiO 2, ZrO2 and Mg2AlOx as well as C-supported other noble metals, Rh, Pd and Pt, with similar particle sizes (1.6-2.0 nm). The kinetic effects of H2 pressures (0-10 MPa), temperatures (433-513 K) and solid bases including Ca(OH)2, Mg(OH)2 and CaCO3 were examined on Ru/C. Ru/C exhibited superior activities and glycol selectivities than Ru on TiO2, ZrO2, Al2O3 and Mg2AlOx, and Pt was found to be the most active metal. Such effects of the metals and supports are attributed apparently to their different dehydrogenation/ hydrogenation activities and surface acid-basicities, which consequently influenced the xylitol reaction pathways. The large dependencies of the activities and selectivities on the H2 pressures, reaction temperatures, and pH values showed their effects on the relative rates for the hydrogenation and base-catalyzed reactions involved in xylitol hydrogenolysis, reflecting the bifunctional nature of the xylitol reaction pathways. These results led to the proposition that xylitol hydrogenolysis to ethylene glycol and propylene glycol apparently involves kinetically relevant dehydrogenation of xylitol to xylose on the metal surfaces, and subsequent base-catalyzed retro-aldol condensation of xylose to form glycolaldehyde and glyceraldehyde, followed by direct glycolaldehyde hydrogenation to ethylene glycol and by sequential glyceraldehyde dehydration and hydrogenation to propylene glycol. Clearly, the relative rates between the hydrogenation of the aldehyde intermediates and their competitive reactions with the bases dictate the selectivities to the two glycols. This study provides directions towards efficient synthesis of the two glycols from not only xylitol, but also other lignocellulose-derived polyols, which can be achieved, for example, by optimizing the reaction parameters, as already shown by the observed effects of the catalysts, pH values, and H2 pressures.
Stereospecific carbon-carbon bond formation using rabbit muscle aldolase
Sawden, J,Turner, N J
, p. 90 - 93 (2007/10/02)
Approaches to the enantiospecific syntheses of shikimic acid and immunoactivator FR 900483 utilising Rabbit Muscle Aldolase condensations have been described.
STEREOSELECTIVE EPOXIDATION OF DIVINYLMETHANOL: A SYNTHETIC APPROACH TO THE PENTITOLS
Holland, David,Stoddart, J. Fraser
, p. 207 - 220 (2007/10/02)
Peroxy-acid epoxidation of divinylmethanol (9), followed by acetylation afforded the acetylated monoepoxides 1 and 2 having the erythro (53percent) and threo (47percent) configurations.Peroxy-acid epoxidation of 1 and 2 yielded the acetylated diepoxides 3 (erythro-erythro, 36percent) and 4 (erythro-threo, 64percent) (from 1), and 4 (erythro-threo, 47percent) and 5 (threo-threo, 53percent) (from 2).Relative configurational assignments were made to 1-5 on the basis of (a) (1)H-n.m.r. chemical-shift and coupling-constant data, (b) the observation that 1 gave only 3 and 4, and that 2 gave only 4 and 5 on epoxidation, and (c) the fact that 3-5 separately undergo epoxidering opening preferentially at their primary carbon atoms with acetate ion in acetic anhydride, to afford the penta-acetates of ribitol, DL-arabinitol, and xylitol, respectively, as major products.Epoxide-ring formation favours the erythro configuration when either peroxy acids or tert-butyl hydroperoxide with catalitically active Ti(4+), V(5+), or Mo(6+) complexes are employed as epoxidation reagents.However, the diastereoselectivities characterising the epoxidations and the regioselectivities governing the epoxide-ring openings are not sufficiently high to constitute an attractive synthesis of euther ribitol, DL-arabinitol, or xylitol from divinylmethanol.
