scholarly journals Hydrogenation of Aromatic Nitrocompounds on Supported Mono- and Bimetallic Catalysts

2016 ◽  
Vol 2 (1) ◽  
pp. 101 ◽  
Author(s):  
A.T. Massenova ◽  
L.R. Sassykova
Keyword(s):  
Bimetallic Catalysts ◽  
Catalytic Properties ◽  
Supported Catalysts ◽  
Bifunctional Catalysts ◽  
Adsorbed Hydrogen ◽  
Reaction Conditions ◽  
Pd Catalysts ◽  
Aromatic Nitrocompounds ◽  
Metal Metal ◽  
Optimal Reaction

<p>Catalytic hydrogenation of substituted aromatic nitrocompounds and hydrocarbons has been studied. It was established that monometallic Pd-catalysts were suitable for reduction of nitrogroups. Bifunctional catalysts such as Rh-Pt, Rh-Pd, Pd-Ru and Rh-Ru were used for hydrogenation of both aromatic ring and nitrogroup and sequence of their hydrogenation depended on support nature. Over Rh-Pt alumina supported catalysts consequent hydrogenation of NO<sub>2</sub> and benzene ring took place, over silica supported catalysts their consecutive hydrogenation was observed. Such catalytic properties of bimetallic Rh-Pt and Rh-Pd catalysts probably connected with metal-metal interaction leading to optimal adsorption strength of uniformly adsorbed hydrogen. The optimal reaction conditions (temperature and hydrogen pressure) have been elaborated for synthesis of alicyclic amines with 95-99% yields.</p>

scholarly journals Catalytic Hydroisomerization of Long-Chain Hydrocarbons for the Production of Fuels

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 534 ◽  
Author(s):  
Päivi Mäki-Arvela ◽  
Taimoor Kaka khel ◽  
Muhammad Azkaar ◽  
Simon Engblom ◽  
Dmitry Murzin
Keyword(s):  
Acid Sites ◽  
Catalyst Stability ◽  
Bifunctional Catalysts ◽  
Research Topics ◽  
Reaction Conditions ◽  
Composite Catalysts ◽  
Branched Alkanes ◽  
Optimal Reaction ◽  
Rapid Mass ◽  
Long Chain

Hydroisomerization of long chain paraffins for the production of branched alkanes has recently been intensively studied due to a large availability of these compounds. The most interesting research topics have been the development of novel bifunctional catalysts to maximize the yield of isomers and to suppress the cracking reactions. Since both of these reactions are catalyzed by Brønsted acid sites, the optimum catalyst exhibits equal amounts of metal and acid sites, and it facilitates rapid mass transfer. Thus, several hierarchical and nano-shaped zeolites have been developed, in addition to composite catalysts containing both micro- and mesoporous phases. In addition to catalyst development, the effect of the reactant structure, optimal reaction conditions, catalyst stability and comparison of batch vs continuous operations have been made.

Synthesis of Phosphonates via Michaelis-Arbuzov Reaction

2017 ◽  
Vol 14 (6) ◽  
pp. 883-903 ◽  
Author(s):  
Boppudi Hari Babu ◽  
Gandavaram Syam Prasad ◽  
Chamarthi Naga Raju ◽  
Mandava Venkata Basaveswara Rao
Keyword(s):  
Reaction Times ◽  
Biologically Active ◽  
Fine Tuning ◽  
Arbuzov Reaction ◽  
Reaction Conditions ◽  
Solvent Type ◽  
Potential Applications ◽  
Synthetic Methodologies ◽  
Optimal Reaction ◽  
The Arbuzov Reaction

Background: Michaelis–Arbuzov reaction has played a key role for the synthesis of dialkyl or diaryl phosphonates by reacting various alkyl or aryl halides with trialkyl or triaryl phosphite. This reaction is very versatile in the formation of P-C bond from the reaction of aliphatic halides with phosphinites or phosphites to yield phosphonates, phosphinates, phosphine oxides. The Arbuzov reaction developed some methodologies, possible mechanistic pathways, selectivity, potential applications and biologically active various phosphonates. Objective: The synthesis of phosphonates via Michaelis–Arbuzov reaction with many new and fascinating methodologies were developed and disclosed in the literature, and these are explored in this review. Conclusion: This review has discussed past developments and vast potential applications of Arbuzov reaction in the synthesis of organophosphonates. As presented in this review, various synthetic methodologies were developed to prepare a large variety of phosphonates. Improvements in the reaction conditions of Lewis-acid mediated Arbuzov rearrangement as well as the development of MW-assisted Arbuzov rearrangement were discussed. Finally, to achieve high selectivities and yields, fine-tuning of reaction conditions including solvent type, temperature, and optimal reaction times to be considered.

Amperometric assay of vitamin C using an ascorbate oxidase enzyme electrode

1979 ◽  
Vol 44 (11) ◽  
pp. 3395-3404 ◽  
Author(s):  
Pavel Posádka ◽  
Lumír Macholán
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Oxygen Electrode ◽  
Ascorbate Oxidase ◽  
Current Response ◽  
Reaction Conditions ◽  
Long Term Storage ◽  
Oxidase Enzyme ◽  
Optimal Reaction

An oxygen electrode of the Clark type, coated by a thin, active layer of chemically insolubilized ascorbate oxidase from squash peelings specifically detects by measuring oxygen uptake 10 to 400 μg of ascorbic acid in 3 ml of phosphate buffer. The record of current response to substrate addition lasts 1-2 min. The ascorbic acid values determined in various samples of fruit juices are in good agreement with the data obtained by titration and polarography. The suitable composition of the membrane and its lifetime and stability during long-term storage are described; optimal reaction conditions of vitamin C determination and the possibilities of interference of other compounds are also examined. Of the 35 phenols, aromatic amines and acids tested chlorogenic acid only can cause a positive error provided that the enzyme membrane has been prepared from ascorbate oxidase of high purity.

scholarly journals A Novel Pseudomonas geniculata AGE Family Epimerase/Isomerase and Its Application in d-Mannose Synthesis

Foods ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1809
Author(s):  
Zhanzhi Liu ◽  
Ying Li ◽  
Jing Wu ◽  
Sheng Chen
Keyword(s):  
3D Structure ◽  
Three Dimensional ◽  
Optimal Temperature ◽  
Reaction Conditions ◽  
Enzymatic Production ◽  
Physiological Properties ◽  
Potential Applications ◽  
Kinetics Of ◽  
Optimal Reaction ◽  
Gene Age

d-mannose has exhibited excellent physiological properties in the food, pharmaceutical, and feed industries. Therefore, emerging attention has been applied to enzymatic production of d-mannose due to its advantage over chemical synthesis. The gene age of N-acetyl-d-glucosamine 2-epimerase family epimerase/isomerase (AGEase) derived from Pseudomonas geniculata was amplified, and the recombinant P. geniculata AGEase was characterized. The optimal temperature and pH of P. geniculata AGEase were 60 °C and 7.5, respectively. The Km, kcat, and kcat/Km of P. geniculata AGEase for d-mannose were 49.2 ± 8.5 mM, 476.3 ± 4.0 s−1, and 9.7 ± 0.5 s−1·mM−1, respectively. The recombinant P. geniculata AGEase was classified into the YihS enzyme subfamily in the AGE enzyme family by analyzing its substrate specificity and active center of the three-dimensional (3D) structure. Further studies on the kinetics of different substrates showed that the P. geniculata AGEase belongs to the d-mannose isomerase of the YihS enzyme. The P. geniculata AGEase catalyzed the synthesis of d-mannose with d-fructose as a substrate, and the conversion rate was as high as 39.3% with the d-mannose yield of 78.6 g·L−1 under optimal reaction conditions of 200 g·L−1d-fructose and 2.5 U·mL−1P. geniculata AGEase. This novel P. geniculata AGEase has potential applications in the industrial production of d-mannose.

scholarly journals Efficient Degradation of Mordant Blue 9 Using the Fenton-Activated Persulfate System

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2532 ◽  
Author(s):  
Md. Nahid Pervez ◽  
Felix Y. Telegin ◽  
Yingjie Cai ◽  
Dongsheng Xia ◽  
Tiziano Zarra ◽  
...  
Keyword(s):  
Butyl Alcohol ◽  
Textile Dye ◽  
Oh Radicals ◽  
Operational Parameters ◽  
Reaction Conditions ◽  
Tert Butyl Alcohol ◽  
Initial Ph ◽  
Fe Complex ◽  
Optimal Reaction ◽  
Activated Persulfate

In this study, a Fenton-activated persulfate (Fe2+/PS) system was introduced for the efficient degradation of Mordant Blue 9 (MB 9) as a textile dye in an aqueous solution. Results showed that the degradation of MB 9 was markedly influenced by operational parameters, such as initial pH, PS concentration, Fe2+ concentration, and initial dye concentration. Optimal reaction conditions were then determined. Inorganic anions, such as Cl− and HCO3−, enhanced the degradation efficiency of MB 9 under optimal conditions. Addition of HCO3− reduced the degradation performance of MB 9, whereas the addition of Cl− increased the degradation percentage of MB 9. In addition, quenching experiments were conducted using methanol and tert-butyl alcohol as scavengers, and methanol was identified as an effective scavenger. Thus, the degradation of MB 9 was attributed to S O 4 • − and •OH radicals. The degradation and mineralization efficiency of MB 9 was significantly reduced using the conventional Fenton process i.e., Fe2+/ hydrogen peroxide (HP) because of the formation of a Fe complex during degradation. Meanwhile, the Fe2+/persulfate (PS) system improved the degradation and mineralization performance.

scholarly journals Software-guided microscale flow calorimeter for efficient acquisition of thermokinetic data

2021 ◽  
Author(s):  
Timothy Aljoscha Frede ◽  
Marlene Dietz ◽  
Norbert Kockmann
Keyword(s):  
Design Of Experiments ◽  
Process Development ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Flow Calorimeter ◽  
Microscale Flow ◽  
Increased Sensitivity ◽  
Important Time ◽  
Optimal Reaction

AbstractFast chemical process development is inevitably linked to an optimized determination of thermokinetic data of chemical reactions. A miniaturized flow calorimeter enables increased sensitivity when examining small amounts of reactants in a short time compared to traditional batch equipment. Therefore, a methodology to determine optimal reaction conditions for calorimetric measurement experiments was developed and is presented in this contribution. Within the methodology, short-cut calculations are supplemented by computational fluid dynamics (CFD) simulations for a better representation of the hydrodynamics within the microreactor. This approach leads to the effective design of experiments. Unfavourable experimental conditions for kinetics experiments are determined in advance and therefore, need not to be considered during design of experiments. The methodology is tested for an instantaneous acid-base reaction. Good agreement of simulations was obtained with experimental data. Thus, the prediction of the hydrodynamics is enabled and the first steps towards a digital twin of the calorimeter are performed. The flow rates proposed by the methodology are tested for the determination of reaction enthalpy and showed that reasonable experimental settings resulted. Graphical abstract A methodology is suggested to evaluate optimal reaction conditions for efficientacquisition of kinetic data. The experimental design space is limited by thestepwise determination of important time scales based on specified input data.

Novel Carbon Structure as Highly Stable Support for Electro-catalyst in Acid Media: Regulating Oxygen Functionalization Behavior of Carbon

2021 ◽  
Author(s):  
Guokang Han ◽  
Yongrong Sun ◽  
Yuxin Liu ◽  
Lingfeng Li ◽  
Xudong Li ◽  
...  
Keyword(s):  
Precious Metal ◽  
Catalytic Properties ◽  
Supported Catalysts ◽  
Carbon Support ◽  
Carbon Structure ◽  
Acid Media

The nature of carbon support has huge effects on the catalytic properties of supported catalysts. When utilized for electrochemical purposes as support for precious metal in acid media, the oxygen...

Sign in / Sign up

Export Citation Format

Share Document