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.

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%.

Kinetic study of the nitric oxide oxidation between 288 and 323 K, under pressure, focus on the oxygen influence on the reaction rate constant

2020 ◽  
Vol 52 (5) ◽  
pp. 329-340 ◽  
Author(s):  
Esther Neyrolles ◽  
José Lara Cruz ◽  
Georgio Bassil ◽  
François Contamine ◽  
Pierre Cezac ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Kinetic Study ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant

Kinetic study of the selective reduction of nitric oxide over vanadia—tungsta—titania/sepiolite catalyst

1994 ◽  
Vol 5 (1-2) ◽  
pp. 117-131 ◽  
Author(s):  
C.U.Ingemar Odenbrand ◽  
Ana Bahamonde ◽  
Pedro Avila ◽  
Jesús Blanco
Keyword(s):  
Nitric Oxide ◽  
Kinetic Study ◽  
Selective Reduction

Chemical Control of Noble Metal Catalysis by Main Group Elements

1997 ◽  
Vol 497 ◽  
Author(s):  
K. Asakura ◽  
K. Okumura ◽  
T. Inoue ◽  
T. Kubota ◽  
W-J. Chun ◽  
...  
Keyword(s):  
High Temperature ◽  
Noble Metal ◽  
Chemical Control ◽  
Noble Metals ◽  
Selective Reduction ◽  
Atomic Layer ◽  
Hydrogenation Reaction ◽  
Main Group ◽  
Main Group Elements ◽  
Temperature Reduction

ABSTRACTThe catalytic interaction of noble metal and main group elements in Rh/one-atomic layer GeO2/SiO2 and Pt/SbOx was investigated. The high temperature reduction produced RhGe and PtSb bimetallic particles in which Pt and Rh were electronically modified to retard catalytic activity. However, unique selective catalyses of Rh/one-atomic layer GeO2/SiO2 for CO hydrogenation reaction to oxygenate compounds and for NO+CO reaction to N2 were found. Under the low temperature reduction of Rh/one-atomic layer GeO2/SiO2 and the high temperature calcination of Pt/SbOx, the oxide phases, GeO2 and SbOx, were stable and the selective reduction of ethylacetate to ethanol and the selective oxidation of iso-C4H10 to methacrolein were observed. The high selectivities were ascribed to synergistic interaction between the noble metals and the main group element oxides through the diffusion of adsorbed species and reaction intermediates. The possibility of chemical control of noble metal-catalyses by main group elements is discussed.

scholarly journals Evaluation of Effective Parameters on Enzymatic Hydrolysis at Low Starch Concentrations

2010 ◽  
Vol 67 (2) ◽  
Author(s):  
Edward MUNTEAN ◽  
Nicoleta MUNTEAN ◽  
Csaba PAIZS ◽  
Cecila ROMAN
Keyword(s):  
Enzymatic Hydrolysis ◽  
High Performance ◽  
Reaction Rate ◽  
Enzymatic Reactions ◽  
Effective Parameters ◽  
Mixing Rate ◽  
Starch Concentration ◽  
Important Interaction ◽  
High Starch ◽  
The One

Enzymatic hydrolysis of starch is one of the most important enzymatic technologies nowadays, leading to important amounts of sweeteners in food industry. It is accomplished at industrial scale using high starch concentrations; the present study deals with a less explored pathway, the one of low starch concentrations, originating from the residual starch in waste waters. The effective parameters of enzymatic starch hydrolysis were studied at laboratory scale, using a commercial enzymatic product (Dextrozyme® GA); experiments were carried out using low concentration starch systems, which were hydrolyzed monitoring the influence of pH, temperature, starch concentration and mixing rate on the reaction rate. Enzymatic reactions were monitored using high performance liquid chromatography, with a system enabling the quantification of glucose, fructose, saccharose and maltose. A complete factorial design at two levels was applied, the measured system’s response being the reaction rate. The obtained data demonstrated that the most important effect on saccharification is due to the pH, this being followed by starch concentration, temperature and mixing rate. Temperature, starch concentration and mixing rate are positively related with the reaction rate, while pH is inversely related with this. Analysis on the parameters’ interactions revealed that the most important interaction is the one between temperature and pH, followed by concentration-temperature and concentration-pH, while the combined interaction concentration-temperature-pH-mixing rate can be considered negligible

scholarly journals Kinetic study of the hydration of propylene oxide in the presence of heterogeneous catalyst

2017 ◽  
Vol 23 (4) ◽  
pp. 573-580 ◽  
Author(s):  
Sema Akyalcin
Keyword(s):  
Kinetic Study ◽  
Heterogeneous Catalyst ◽  
Propylene Oxide ◽  
Rate Constants ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Catalyst Loading ◽  
Catalyzed Reactions ◽  
Kinetics Of ◽  
Homogeneous Mechanism

The kinetics of the hydration of propylene oxide was studied using a pressurized batch reactor for both uncatalyzed and heterogeneously catalyzed reactions. Lewatit MonoPlus M500/HCO3 - was used as heterogeneous catalyst, which showed better performance than Dowex Marathon A/HCO3 -. The effects of the parameters, namely internal and external diffusion resistances, temperature, catalyst loading and mole ratios of reactants, on the reaction rate were studied. The uncatalyzed and heterogeneously catalyzed reactions were proven to follow a series-parallel irreversible homogeneous mechanism. The temperature dependencies of the rate constants appearing in the rate expressions were determined.

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