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Excited Particles and Heterogeneous Stages in Chemistry

#A-744


Investigations Processes of Gas-Phase Oxidation with Account of Excited Particles and Heterogeneous Stages in Well-Stirred Reactor for Design of Technologies Converting Organic Compounds to Valuable Products

Tech Area / Field

  • CHE-THE/Physical and Theoretical Chemistry/Chemistry
  • INS-MEA/Measuring Instruments/Instrumentation

Status
3 Approved without Funding

Registration date
18.06.2001

Leading Institute
Institute of Chemical Physics, Armenia, Yerevan

Supporting institutes

  • Yerevan Scientific Research Institute of Communication Facilities (YSRICF), Armenia, Yerevan\nA.I. Alikhanyan National Science Laboratory, Armenia, Yerevan

Collaborators

  • Seoul National University, Korea, Seoul\nHeriot-Watt University, UK, Edinburgh\nOptimage Ltd, UK, Edinburgh\nConsiglio Nazionale Delle Ricerche / Istituto di Ricerche Sulla Combustione, Italy, Napoli\nFlorida State University, USA, FL, Tallahassee

Project summary

Introduction.

At the moment is known large number of processes, carried out in chemical technologies, engines of internal combustion, in numerous chemical generators and also, proceeding in environment rounding us, including in earth atmosphere, in which the important role is played the chain gas-phase reactions with the complex mechanism. Their study is urgent, as concern with such major aspects of modern chemistry, as obtaining of a number of useful products, increase of efficiency and reliability of work of chemical units and processes, proceeding in an environment and influencing to its condition. In this connection a problem of creation of new technologies gets the special gravity which high-effective manufactures will provide at the minimum pollution of an environment. For this purpose it is necessary to establish true mechanisms of these processes and to investigate probable dynamic modes of their proceeding.

The special place among the above mentioned processes are occupied the processes of low-temperature oxidation of organic compounds with chain branching mechanism. The work on improvement of these processes are conducted as on a way of modernization of used apparatus (designing and test of new means of manufacture – of reactors), and on a way of stimulation of these processes by different physical and chemical ways (the application of high and superhigh-frequency charges, lasers, coating of surfaces of reactors, and also, use of catalysts and impurity).

The specified directions of research of processes of gas-phase oxidation with chain branching mechanism are one of urgent problems of modern chemistry.

The purpose of work is:

– Creation of experimental technique with unit of registration of light radiation of reaction on the basis of a flow reactor, ensuring mixing of gases with speed, superior propagation of front of a cool flame, in given experimental conditions.

– Research of the mechanism of formation and role of exited molecules in process of heterogeneous-homogeneous oxidation of organic compounds (aldehydes, hydrocarbons).

– Modeling of the mechanism of the installation of dynamic regimes at cool flame oxidation of organic compounds.

– role of surface processes in installation of oscillation modes near to walls of a reactiona vessel;
– formation and propagation of concentration structures in the reactor.


– Design of choice and drawing of coatings on a surface of a reactor, and also, study of influence of the electrical and structural characteristics of these coatings on process of gas-phase oxidation of organic compounds.

– Creation of cool flames at temperatures lower then known by the way of his stimulation by the external factors with the purpose of increase of selectivity of reactions of oxidation of organic compounds.

– Experimental study of reactions of oxidation of organic compounds in a regime of cold flame.

– Creation of the serial device for measurement of temperature of gases in flow conditions.

In result advanced technology of realization of processes on the basis of developed models and offered advanced reactor will be offered.

The offered project is based on achievement of group to the present moment:

Experimental part.

Is created and previously is tested a well-stirred reactor in a flow on the basis of known in the literature [1] samples. Preliminary development for creation of the device of measurement of temperature of gases in flow conditions, based on dependence of gases dynamic viscosity coefficient from temperature are available.

Theoretical part.

Within the framework of the decision of the problem the process of low-temperature oxidation of acetaldehyde in flow conditions is modeled in view of influence of exited intermediate products, formed by heterogeneous recombination of radicals. On the basis of experimental data that at cool flame combustion of hydrocarbons is observed a light emission, caused by occurrence of exited molecules formaldehyde [2] and taking into account, that in conditions of experiment these molecules can arise mainly on a surface of a reaction vessel, and also, that formaldehyde is inhibitor of reaction oxidation of acetaldehyde, a heterogeneous-homogeneous mechanism, well describing the experimental information [3-6], was considered. The model well describes occurrence of some dynamic mod of reaction (frequency of oscillations) known of experiment. Analysis of an offered model depending on the initial conditions, state of a surface and etc. is spent. Dependence of number pulses in system, frequency of oscillations and modes of oscillation from redistribution of internal energy and condition of a surface is found. Is shown, that the nonlinear connection, located near to a surface, is the reason of formation of volume structures.

A method of measurement of temperature of gases in flow conditions, based on dependence of coefficient of dynamic viscosity of gases on temperature [7] is theoretically developed.

In result of researches it is supposed to receive the fundamental knowledge of a nature and mechanisms of formation cold flame and role of internal energy of particles and heterogeneous stages at an establishment of dynamic modes in chain gas-phase reactions.

The applied importance of work consists in creation of technical apparatus and offer of new technology of realization of processes of oxidation of organic compounds, as in chemical production, and in other areas of an industry.

The realization of the given project will promote the maintenance of fundamental and applied researches, development of technologies especially in area of chemical manufactures and guards of an environment.

Scope of Activities, as a whole, will consist in following:

– Design of unit radiation registration of reaction medium in a range of a spectrum from infra red up to ultra violet.

– Creation of the serial device for measurement of temperature of gas in flow conditions and its test.

– Selection of special coatings for walls of a reactor.

– Development of a general model of processes of gas-phase oxidation of organic compounds on the basis of received experimental data with account of heterogeneous-homogeneous stages and electronically- and vibrationally excited particles.

– The receiving of cool flames in reactions of oxidation of organic compounds at temperatures lower then known and registration of a spectrum of a reaction mixture.

– Summarize of received results and distribution on their basis of the recommendations on improvement of technology of industrial processing of various organic compounds.

In realization of the project will participate:

– Institute of Chemical Physics name aft. A.B.Nalbandyan NAS RA, Armenia;


– Yerevan Institute of Physics, Armenia;
– Yerevan Scientific Research Institute of Communication Facilities JSC, Armenia
– Florida State University, USA;
– Heriot-Watt University, UK;
– Optimage LTD, UK;
– Instituto Ricerche sulla Combustione of the CNR; Italy.

The accounting materials will be submitted as the scientific publications, reports, manufacturing of the equipment and protocols of tests.

The cooperation to foreign collaborators will come true on a line of an exchange of scientific information, discussion of stage by stage results of work, rendering of assistance for participation in international conferences, representation of an opportunity of realization of some joint work for development of the equipment and construction of some units of experimental installation, realization of joint working seminars.

Literature.

1. Gray P., Griffiths J.F., Hasko S. M., Lignola P. G., Proc,. R. Soc., London, A374, 313, 1981.

2. Kondratiev V., Spectrum of the Cold Flame of Ether, Acta Physiochem, USSR, 4, 556, 1936.

3. Sargsyan G. N., The Role of Heterogeneous Factors in exciteting of Concentrations Autooscillations under Oxidations of Acetaldehyde, Dokl. AN Arm. N3, 1995.

4. Sargsyan G. N., Yessayan R. S., Vardanyan I. A., 26th International Symposium on Combustion, Napoly, Italy, 1995, Abstracts of Work-in-Progress Posters, p.56.

5. Sargsyan G. N., Yessayan R. S., Vardanyan I. A., Analysis of heterogeneous – homogeneous model, describing oscillations in system CH3CHO + O2, APPLIED Catalis A; General 203 (2000) 285-291.

6. Sargsyan G. N., Vardanyan I. A., Modeling of Cool Flame Combustion of Gas Mixtures in Flow Conditions, 9th International Symposium on Flow, Visualization, CD Rom Proceedings, p. 266-1 –266-10, Edinburg, Scotland, UK, August 22-27, 2000.

7. Sargsyan G. N., Yessayan R. S., Method of Measurment of Temperature in Gas Flowe Using Temperature Dependence of Dynamic Viscosity Coefficient, 8th International Symposium on Flow Visualization, Printed Proceedings, Sorrento, September 1-4, 1998, p.103.


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