scholarly journals SYNTHEIS OF NI IMPREGNATED HYPERCROSSLINKED POLYSTERENE FOR CATALITIC HYDROGENATION OF D-GLUCOSE

2020 ◽  
Vol 63 (5) ◽  
pp. 51-58
Author(s):  
Roman V. Brovko ◽  
Valentin Yu. Doluda ◽  
Olga V. Lefedova ◽  
Ilya A. Tarasyuk ◽  
Dmitry V. Filippov ◽  
...  
Keyword(s):  
Reaction Rate ◽  
High Surface ◽  
Surface Concentration ◽  
Surface Hydrophobicity ◽  
Hydrogenation Reaction ◽  
Hypercrosslinked Polystyrene ◽  
Active Metal ◽  
Glucose Isomerization ◽  
Rigid Matrix ◽  
Type Nickel

Development of efficient catalysts is in focus of modern chemical technology for production of fine chemicals. D-sorbitol is widely used as sweetener, food additive and fuel compound is typically produced by D-glucose hydrogenation over Ni-Reney catalyst. However, this catalyst is characterized by not sufficient stability and selectivity to D-sorbitol formation. The described study is devoted to synthesis of nickel containing hypercrosslinked polystyrene for D-glucose hydrogenation process. Hypercrosslinked polystyrene is one of the representatives of crosslinked polymers with rigid matrix applicable for metal nanoparticles synthesis. However, hypercrosslinked polystyrene is characterized by high surface hydrophobicity that prevent impregnation of high amount of active metal over it surface. To overcome this disadvantage hypercrosslinked polystyrene was modified by hydrogen peroxide, chlorine and ammonia. A series of nickel based catalyst theoretically containing 25wt.% of nickel were synthesized. Modification of hypercrosslinked polystyrene results in appropriate increase in surface concentration of active metal. Synthesized Ni based catalysts were characterized by comparable Ni loading varying from 20.1 wt.% to 23.2 wt.%. Some increase in Ni loading can be subscribed to presence of surface-active groups in a case of modified hypercrosslinked polystyrene application. Mesopores surface area decrease from 126 m2/g to 69 m2/g in case of catalysts on modified hypercrosslinked polystyrene. Catalytic hydrogenation of D-glucose over synthesized Ni-containing catalysts showed considerable increase in turnover frequency (TOF) for all samples compare to commonly used Reney type nickel. Increase in TOF can be subscribed to appropriate increase of active metal surface concentration. Beside, some increase in catalyst selectivity to sorbitol took place. Considerable improvement of selectivity to sorbitol can be explained by increasing of desired D-glucose hydrogenation reaction rate, while reaction rate of D-glucose isomerization process to D-fructose remain the same. The achieved TOF for most active catalyst was found to be 0.27 s-1 and catalysts selectivity to D-sorbitol 98%.

scholarly journals KINETIC STUDY OF CARBOXYLIC GROUP HYDROGENATION OF FATTY ACIDS

2020 ◽  
pp. 47-55
Author(s):  
Маргарита Александровна Монжаренко ◽  
Антонина Анатольевна Степачёва ◽  
Эсфирь Михайловна Сульман
Keyword(s):  
Kinetic Study ◽  
Reaction Rate ◽  
Model Compound ◽  
Selective Reduction ◽  
Hydrogenation Reaction ◽  
Hypercrosslinked Polystyrene ◽  
Target Product ◽  
Stearyl Alcohol ◽  
Mixing Rate ◽  
Carboxylic Groups

Работа посвящена кинетическому исследованию селективного восстановления карбоксильной группы стеариновой кислоты, выбранной в качестве модельного соединения, с целью получения стеарилового спирта. В качестве катализатора был выбран 1%Pd/MN-270 - палладий, нанесенный на полимерную матрицу сверхсшитого полистирола гидротермальным методом. Проведено исследование влияния температуры, парциального давления водорода, концентрации субстрата, скорости перемешивания на скорость процесса гидрирования карбоксильной группы стеариновой кислоты, а также на селективность образования целевого продукта - стеарилового спирта. This work is devoted to the kinetic study of the selective reduction of carboxylic groups of stearic acid chosen as a model compound in order to obtain stearyl alcohol. 1%Pd/MN-270 palladium deposited on the polymeric matrix of hypercrosslinked polystyrene by hydrothermal method was chosen as a catalyst. The study of the influence of temperature, hydrogen partial pressure, substrate concentration, mixing rate on the hydrogenation reaction rate and the selectivity of the formation of target product was performed.

High surface hydrophobicity of hemagglutinatingVibrio cholerae and other vibrios

1982 ◽  
Vol 7 (6) ◽  
pp. 357-362 ◽  
Author(s):  
Ahmed Faris ◽  
Mats Lindahl ◽  
Torkel Wadström
Keyword(s):  
High Surface ◽  
Surface Hydrophobicity

scholarly journals Catalytic Activity of High-Surface-Area Amorphous MgO Obtained from Upsalite

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1338
Author(s):  
Marek Gliński ◽  
Ewa M. Iwanek (nee Wilczkowska) ◽  
Urszula Ulkowska ◽  
Agnieszka Czajka ◽  
Zbigniew Kaszkur
Keyword(s):  
Surface Area ◽  
Carbonyl Compounds ◽  
Main Product ◽  
High Surface ◽  
High Surface Area ◽  
Hydrogenation Reaction ◽  
Transfer Hydrogenation ◽  
Reaction Conditions ◽  
Synthesis Conditions ◽  
Transfer Hydrogenation Reaction

The first aim of the research was to synthesize a pure Upsalite, which is an amorphous form of MgCO3, by modifying a procedure described in the literature, so that it would be the precursor of a high-surface, amorphous magnesium oxide. The results indicate that within the studied reaction conditions, the type of alcohol used as the reactant has the most pronounced effect on the yield of reaction. From the two alcohols that led to the highest yield of Upsalite, methanol gave a substantially larger surface area (794 vs. 191 m2 g−1). The optimized synthesis conditions of Upsalite were used to obtain MgO via thermolysis, whose activity in the transfer hydrogenation reaction (THR) from ethanol, 2-propanol and 2-pentanol to various carbonyl compounds was determined. The optimal conditions for the thermolysis were as follows: vacuum, T = 673 K as the final temperature, and a heating rate of 2 deg min−1. The high-surface, amorphous magnesia (SBET = 488 m2 g−1) was found to be a very selective catalyst to 4-t-butylcyclohexanone in THR, which led to a diastereoselectivity of over 94% to the E-isomer of 4-t-butylcyclohexanol for more than 3 h, with conversions of up to 97% with either 2-propanol or 2-pentanol as the hydrogen donor. In the case of acrolein and 2-n-propylacrolein being used as the hydrogen acceptors, the unsaturated alcohol (UOL) was the main product of the reaction, with higher UOL yields noted for ethanol than 2-propanol.

AutoaggregatingYersinia enterocoliticaexpress surface fimbriae with high surface hydrophobicity

1983 ◽  
Vol 55 (1) ◽  
pp. 97-100 ◽  
Author(s):  
A. Faris ◽  
M. Lindahl ◽  
Å. Ljungh ◽  
D.C. Old ◽  
T. Wadström
Keyword(s):  
High Surface ◽  
Surface Hydrophobicity

A Steady-State Model for Coupled Defect Impurity Diffusion in Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
F. F. Morehead ◽  
R. F. Lever
Keyword(s):  
Steady State ◽  
High Surface ◽  
Local Equilibrium ◽  
Surface Concentration ◽  
Extended Model ◽  
High Concentration ◽  
Steady State Model ◽  
High Surface Concentration ◽  
Phosphorus In Silicon ◽  
Diffusion Profiles

AbstractWe extend our earlier model which was proposed to explain tails in the diffusion profiles of high concentration boron and phosphorus in silicon. Our quasi-steady-state approach is generalized here to include both vacancies (V) and interstitials (I) at equivalent levels. I-V recombination is regarded as near local equilibrium, occurring through reactions of the defects with defect-impurity pairs. This approach leads to the well-known plateau, kink and tail in high surface concentration P diffusions in Si and to the less well recognized tails in B as well. Our extended model, in its simplest form, allows a more complete and less restrictive treatment of Au diffusion in Si. An important advantage is the direct inclusion of these defect-impurity interactions and the resulting gradients in the defect concentrations.

Effect of Microalloying with Ti or Cr on the Corrosion Behavior of Al-Ni-Y Amorphous Alloys

CORROSION ◽  
10.5006/2451 ◽  
2017 ◽  
Vol 74 (1) ◽  
pp. 66-74 ◽  
Author(s):  
L.M. Zhang ◽  
A.L. Ma ◽  
H.X. Hu ◽  
Y.G. Zheng ◽  
B.J. Yang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Photoelectron Spectroscopy ◽  
Amorphous Alloys ◽  
Diffusion Mechanism ◽  
High Surface ◽  
Control Sample ◽  
Surface Concentration ◽  
Passive Films ◽  
High Surface Concentration

The effect of microalloying with Ti or Cr on the corrosion behavior of Al-Ni-Y amorphous alloys in 0.1 M NaCl solution was studied by potentiodynamic polarization, Mott-Schottky, and x-ray photoelectron spectroscopy techniques. Microalloying with Ti or Cr could greatly improve the corrosion resistance of Al-Ni-Y amorphous alloys. A high surface concentration of Ti or Cr in the passive films was detected, which should be responsible for the improved corrosion resistance compared to the control sample. The possible process of Ti or Cr involved in the passive films was proposed in terms of the point defect model and the vacancy diffusion mechanism. Furthermore, the effect of Ti was stronger than Cr because of the higher film resistance as well as the higher surface concentration. The different passivation abilities and atomic radiuses between Ti and Cr were presented to explain the better microalloying effect of Ti compared to Cr.

Mucin Coating on Hydrophobic Polymer Materials

1999 ◽  
Vol 599 ◽  
Author(s):  
L. Shi ◽  
K. D. Caldwell
Keyword(s):  
Submaxillary Gland ◽  
Surface Concentration ◽  
Surface Hydrophobicity ◽  
Contact Angles ◽  
Polymer Materials ◽  
Adsorption Model ◽  
Kinetics Parameters ◽  
Water Contact ◽  
Long Term Observation

AbstractIn this work, the adsorption isotherm and kinetics of bovine submaxillary gland mucin (BSM) onto a hydrophobic polystyrene surface were studied by the solution depletion method, in which mucin surface concentrations were analyzed by amino acid analysis. Using a Langmuir adsorption model and non-linear curve fitting, kinetics parameters, kon and koff were determined. The coating was found to be very stable with very limited desorption (less than 2%) from a long term observation. By measuring the water contact angles, the changes in surface hydrophobicity due to mucin coating were monitored on four polymer materials, namely polymethylmethacrylate (PMMA), polyurethane (PU), polystyrene (PS), and silicone. After coating, all the hydrophobic surfaces turned into very hydrophilic. A strict correlation between mucin surface concentration and surface wettability has been found.

scholarly journals Carbon Monoxide Adsorption Studies on an Ru:Mn Bimetallic Alloy System for the Determination of Active Metal Sites

1996 ◽  
Vol 13 (6) ◽  
pp. 489-493 ◽  
Author(s):  
S. Tajammul Hussain
Keyword(s):  
High Surface ◽  
Co Adsorption ◽  
High Surface Area ◽  
Alloy System ◽  
Impregnation Method ◽  
Electronic Effects ◽  
Alumina Support ◽  
Bimetallic Alloy ◽  
Active Metal ◽  
Adsorption Of Co

A supported ruthenium:manganese bimetallic alloy system dispersed on a high surface area alumina support was prepared by the co-impregnation method. The adsorption of CO at atmospheric pressure was carried out in order to determine the number of active metal sites present. The data indicate that manganese was present as a covering layer on the surface of the ruthenium. With increasing manganese loading decreasing adsorption of CO was observed, indicating that the presence of manganese masked the active ruthenium sites responsible for CO adsorption. No CO adsorption occurred on isolated manganese sites. The data were interpreted in terms of the geometric and possible electronic effects caused by the addition of manganese.

scholarly journals Isolation, identification and potential probiotic characterization of lactic acid bacteria from Thai traditional fermented food

2021 ◽  
Vol 7 (4) ◽  
pp. 431-446
Author(s):  
Sunisa Suwannaphan ◽  
Keyword(s):  
Lactic Acid ◽  
Gastrointestinal Tract ◽  
Lactic Acid Bacteria ◽  
Pathogenic Bacteria ◽  
High Surface ◽  
Surface Hydrophobicity ◽  
Fermented Food ◽  
Probiotic Properties ◽  
Two Samples ◽  
Traditional Fermented Food

<abstract> <p>The probiotic potential of lactic acid bacteria (LAB) isolated from Thai traditional fermented food was investigated. Forty-two samples were collected from four markets in Phra Nakhon Si Ayutthaya Province. Out of 50 isolated LAB, 6 (a3, f4, f8, K1, K4 and K9) obtained from pla-ra and bamboo shoot pickle samples showed high tolerance to gastrointestinal tract conditions. These isolates were selected to identify and characterize their probiotic properties. Isolate a3 was identified as <italic>Weissella thailandensis</italic>, isolates f4 and f8 were identified as belonging to <italic>Enterococcus thailandicus</italic> and isolates K1, K4 and K9 were determined as <italic>Limosilactobacillus fermentum</italic>. All six LAB exhibited high autoaggregation ability (93.40–95.01%), while <italic>W. thailandensis</italic> isolate a3 showed potential for coaggregation in almost all the pathogenic bacteria tested. Cell-free supernatant (CFS) obtained from all isolates did not inhibit <italic>Staphylococcus aureus</italic>. CFS derived from <italic>L. fermentum</italic> isolate K4 showed the most efficient antimicrobial activity, in particular against Gram-negative bacteria, while <italic>L. fermentum</italic> isolate K4 presented high surface hydrophobicity in the presence of xylene and n-hexane. All LAB isolates were found to be resistant to clindamycin and nalidixic acid, whereas <italic>E. thailandicus</italic> isolate f8 exhibited resistance to most of the antibiotics tested. <italic>L. fermentum</italic> isolate K4 showed promise as a suitable probiotic candidate for future applications in the food industry due to tolerance to gastrointestinal tract conditions with high surface hydrophobicity and inhibited most of the pathogens tested.</p> </abstract>

Sign in / Sign up

Export Citation Format

Share Document