Mechanism of the oscillatory decomposition of the dithionite ion in a flow reactor

2002 ◽  
pp. 790-791 ◽  
Author(s):  
Klára M. Kovács ◽  
Gyula Rábai
Keyword(s):  
Flow Reactor ◽  
Dithionite Ion

Hydrogenolysis of glucose and fructose in glycol solutions over CuO-MgO-ZrO2 catalyst

2020 ◽  
pp. 48-55
Author(s):  
M.E. Sharanda ◽  
◽  
E.A. Bondarenko ◽  
Keyword(s):  
Ethylene Glycol ◽  
Propylene Glycol ◽  
Flow Reactor ◽  
General Trend ◽  
Raw Materials ◽  
Reaction Products ◽  
Renewable Raw Materials ◽  
High Partial Pressure ◽  
Zro2 Catalyst ◽  
Phase Process

Ethylene glycol and propylene glycol are important representatives of polyols. On an industrial scale, they are obtained from petrochemical raw materials. Within a decade, significant efforts were made for the producing of polyols from biologically renewable raw materials - carbohydrates. The general trend for carbohydrate hydrogenolysis includes application of liquid-phase process with the use of modified metal-oxide catalysts, at 120-120 ° C and pressure of 3MPa or above. So high pressure is used for the reason to increase hydrogen solubility, and also due to the high partial pressure of low boiling solvents. We supposed that usage of high boiling solvents could allow hydrogenolysis to be performed at the lower pressure. Ethylene glycol and propylene glycol are of particular interest as such kind of solvent since they are both the main products of glucose hydrogenolysis. In this work, the process of hydrogenolysis of glucose and fructose over Cu / MgO-ZrO2 catalyst have been studied at temperature range of 160-200 °C and a pressure of 0.1-0.3 MPa in a flow reactor. The solvents were simultaneously the target products of the reaction - ethylene glycol and / or propylene glycol. Gas chromatography and 13C NMR were used for the reaction products identification. It was found that the solubility of glucose in propylene glycol is 21 % by weight, and in ethylene glycol 62% by weight. It was pointed out that the process of hydrogenolysis can take place at a pressure close to atmospheric. Under these conditions, the conversion of hexoses reaches 96-100 %. The reaction products are preferably propylene glycol and ethylene glycol. The total selectivity for C3-2 polyols is 90-94 %, that is higher than in the hydrogenolysis of glucose in aqueous solution.

Conversion of fructose into methyl lactate over SnO2/Al2O3 catalystin flow regime

2020 ◽  
pp. 43-47
Author(s):  
S.V. Prudius ◽  
◽  
N.L. Hes ◽  
A.M. Mylin ◽  
V.V. Brei ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Practical Interest ◽  
Dimethyl Acetal ◽  
Racemic Mixture ◽  
Process Conditions ◽  
Impregnation Method ◽  
Aqueous Methanol ◽  
Methyl Lactate ◽  
Al2o3 Catalyst ◽  
Target Reaction

In recent years, numerous researchers have focused on the development of catalytic methods for processing of biomass-derived sugars into alkyl lactates, which are widely used as non-toxic solvents and are the starting material for obtaining monomeric lactide. In this work, the transformation of fructose into methyl lactate on Sn-containing catalyst in the flow reactor that may be of practical interest was studied. The supported Sn-containing catalyst was ob-tained by a simple impregnation method of granular γ-Al2O3. The catalytic ex-periments were performed in a flow reactor at temperatures of 160-190 °C and pressure of 3.0 MPa. The 1.6-9.5 wt.% fructose solutions in 80% aqueous methanol were used as a reaction mixture. It was found that addition to a reac-tion mixture of 0.03 wt.% potassium carbonate leads to the increase in selec-tivity towards methyl lactate on 15% at 100% conversion of fructose. Prod-ucts of the target reaction С6Н12О6 + 2СН3ОН = 2С4Н8О3 + 2Н2О were ana-lyzed using 13C NMR method. The following process conditions for obtaining of 65 mol% methyl lactate yield at 100% fructose conversion were found: use of 4.8 wt.% fructose solution in 80% methanol, 180 °С, 3.0 МПа and a load on catalyst 1.5 mmol C6H12O6/mlcat/h at contact time of 11 minutes. The cata-lyst productivity is 2.0 mmol C4H8O3/mlcat/h and the by-productі are 1,3-dihydroxyacetone dimethyl acetal (20%) and 5-hydroxymethylfurfural (10%). It should be noted that a racemic mixture of L- and D-methyl lactates has been obtained by conversion of D-fructose on the SnO2/Al2O3 catalyst. The SnO2/Al2O3 catalyst was found to be stable for 6 h while maintaining full fruc-tose conversion at 55–70% methyl lactate selectivity. After regeneration the catalyst completely restores the initial activity.

Droplet Factories: Synthesis and Assembly of Silver and Palladium Nanoparticles at the Liquid-Liquid Interface

2019 ◽  
Author(s):  
Suchanuch Sachdev ◽  
Rhushabh Maugi ◽  
Sam Davis ◽  
Scott Doak ◽  
Zhaoxia Zhou ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Reaction Rate ◽  
Tertiary Structure ◽  
Flow Reactor ◽  
Pd Nanoparticles ◽  
Subsequent Removal ◽  
Immiscible Liquids ◽  
Flow Reactors ◽  
Droplet Flow ◽  
One Step

<div>The interface between two immiscible liquids represent an ideal substrate for the assembly of nanomaterials. The defect free surface provides a reproducible support for creating densely packed ordered materials. Here a droplet flow reactor is presented for the synthesis and/ or assembly of nanomaterials at the interface of the emulsion. Each droplet acts as microreactor for a reaction between decamethylferrocene (DmFc) within the hexane and metal salts (Ag+/ Pd2+) in the aqueous phase. The hypothesis was that a spontaneous, interfacial reaction would lead to the assembly of nanomaterials creating a Pickering emulsion. The subsequent removal of the solvents showed how the Ag nanoparticles were trapped at the interface and retain the shape of the droplet, however the Pd nanoparticles were dispersed with no tertiary structure. To further exploit this, a one-step process where the particles are synthesised and then assembled into core-shell materials was proposed. The same reactions were performed in the presence of oleic acid stabilise Iron oxide nanoparticles dispersed within the hexane. It was shown that by changing the reaction rate and ratio between palladium and iron oxide a continuous coating of palladium onto iron oxide microspheres can be created. The same reaction with silver, was unsuccessful and resulted in the silver particles being shed into solution, or incorporated within the iron oxide micro particle. These insights offer a new method and chemistry within flow reactors for the creation of palladium and silver nanoparticles. We use the technique to create metal coated iron oxide nanomaterials but the methodology could be easily transferred to the assembly of other materials.</div><div><br></div>

Renewable Energy from Agricultural Waste

2018 ◽  
Vol 69 (6) ◽  
pp. 1363-1366 ◽  
Author(s):  
Stefania Daniela Bran ◽  
Petre Chipurici ◽  
Mariana Bran ◽  
Alexandru Vlaicu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gas Chromatography ◽  
Continuous Flow ◽  
Laboratory Experiments ◽  
Fermentation Process ◽  
Flow Reactor ◽  
Agricultural Waste ◽  
Continuous Flow Reactor ◽  
Natural Support ◽  
Co2 Flow

This paper has aimed at evaluating the concentration of bioethanol obtained using sunflower stem as natural support, molasses as carbon source and Saccharomyces cerevisiae yeast in a continuous flow reactor. The natural support was tested to investigate the immobilization/growth of S. cerevisiae yeast. The concentration of bioethanol produced by fermentation was analyzed by gas chromatography using two methods: aqueous solutions and extraction in organic phase. The CO2 flow obtained during the fermentation process was considered to estimate when the yeast was deactivated. The laboratory experiments have highlighted that the use of plant-based wastes to bioconversion in ethanol could be a non-pollutant and sustainable alternative.

A stochastic model for two-station hydraulics exhibiting transient impact

1997 ◽  
Vol 36 (5) ◽  
pp. 19-26 ◽  
Author(s):  
J. L. Jacobsen ◽  
H. Madsen ◽  
P. Harremoès
Keyword(s):  
Parameter Estimation ◽  
Flow Reactor ◽  
Deterministic Model ◽  
Plug Flow ◽  
Stochastic Methods ◽  
Sewer System ◽  
Statistical Tool ◽  
Water Level Variation ◽  
Deterministic Description ◽  
Linear Reservoir

The objective of the paper is to interpret data on water level variation in a river affected by overflow from a sewer system during rain. The simplest possible, hydraulic description is combined with stochastic methods for data analysis and model parameter estimation. This combination of deterministic and stochastic interpretation is called grey box modelling. As a deterministic description the linear reservoir approximation is used. A series of linear reservoirs in sufficient number will approximate a plug flow reactor. The choice of number is an empirical expression of the longitudinal dispersion in the river. This approximation is expected to be a sufficiently good approximation as a tool for the ultimate aim: the description of pollutant transport in the river. The grey box modelling involves a statistical tool for estimation of the parameters in the deterministic model. The advantage is that the parameters have physical meaning, as opposed to many other statistically estimated, empirical parameters. The identifiability of each parameter, the uncertainty of the parameter estimation and the overall uncertainty of the simulation are determined.

Efficient Production of Light Olefin Based on Methanol Dehydration: Simulation and Design Improvement

2020 ◽  
Vol 23 ◽  
Author(s):  
S. Majid Abdoli ◽  
Mahsa Kianinia
Keyword(s):  
Dimethyl Ether ◽  
Flow Reactor ◽  
New Technology ◽  
Plug Flow ◽  
Light Olefins ◽  
Efficient Production ◽  
Actual Process ◽  
Light Olefin ◽  
Aspen Hysys ◽  
Improved Design

Background: Ethylene, propylene, and butylene as light olefins are the most important intermediates in the petrochemical industry worldwide. Methanol to olefins (MTO) process is a new technology based on catalytic cracking to produce ethylene and propylene from methanol. Aims and Objective: This study aims to simulate the process of producing ethylene from methanol by using Aspen HYSYS software from the initial design to the improved design. Methods: Ethylene is produced in a two-step reaction. In an equilibrium reactor, the methanol is converted to dimethyl ether by an equilibrium reaction. The conversion of the produced dimethyl ether to ethylene is done in a conversion reactor. Changes have been made to improve the conditions and get closer to the actual process design done in the industry. The plug flow reactor has been replaced by the equilibrium reactor, and the distillation column was employed to separate the dimethyl ether produced from the reactor. Result and Conclusion: The effect of the various parameters on the ethylene production was investigated. Eventually, ethylene is

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