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Nanocrystalline Catalysts and Sorbents

#2577


New Catalysts and Sorbents with Application of Nanocrystalline Metals, Oxides and Diamonds

Tech Area / Field

  • MAT-COM/Composites/Materials

Status
3 Approved without Funding

Registration date
01.08.2002

Leading Institute
VNIITF, Russia, Chelyabinsk reg., Snezhinsk

Supporting institutes

  • Moscow State University / Department of Chemistry, Russia, Moscow\nUral Branch of RAS / Institute of Metal Physics, Russia, Sverdlovsk reg., Ekaterinburg

Collaborators

  • Keio University / Faculty of Science and Technology, Japan, Yokohama\nShimadzu Deutschland GmbH, Germany, Duisburg\nKyoto University / Energy and Environment Association, Japan, Kyoto

Project summary

The purpose of the project is development of scientific bases of technology of obtaining a new class of sorbents and catalysts based on nanocrystalline metals, oxides and nanodiamonds, research of their physical and chemical properties and determination of the most perspective ways of practical use in high technologies.

One of fundamental results of solid state physics and chemistry of the recent time is that the majority of physical and chemical properties of solid states become size-dependent, when the solid state size is diminished up to several interatomic distances in one, two or three dimensions.

Synthesis of new nanostructure materials and detection of their unusual properties became the subject of detailed research in the last years and is of interdisciplinary character.

For creation of particles in nanometer range various methods are widely used. In the project it is supposed to use the method of gas condensation and mechanical alloying for synthesis of metal and oxide materials. Complex oxide nanocrystalline catalytic systems are to be obtained also in sub- and supercritical water. Besides, explosive synthesis of nanodiamonds and nanooxides of metals occupies a special place in the work.

Detonation nanodiamonds have an advanced surface, combine chemical stability of diamond core and high activity of surface functional groups. Unique material, nanodiamonds, serve as the basis for creation of a new class of sorbents. Researches have shown that nanodiamonds have high sorption activity of organic substances, gases, and electrolyte ions. In size of static sorption capacity, according to the way of synthesis and degree of purification nanodiamonds exceed samples of known grades of industrial carbon.

High stability of nanodiamonds to radiation makes it possible to consider them as highly effective sorbents of radionuclides. The results, confirming high cation-exchange properties of nanodiamonds, in particular, in cesium, have been obtained. Under gamma irradiation of nanodiamonds the beginning of removal of surface groups responsible for cation sorption was noticed only at application of big capacity streams, at which other materials usually are destructed (more than 500 Mrad).

But application of nanodiamonds as sorbents of valuable components or purification of various environments were carried out mostly by initiatory groups and are at the initial stage.

When the use of nanomaterials in various fields is growing, particularly, in chemistry, biomedical industry and others, the modern materials science faces the necessity of more and more exact control of properties of final products and creation of new materials satisfying special requirements.

It is necessary to admit, that the practical use of nanoobjects may be effective only in case of deep understanding how atomic, molecular and mesoscopical features of such solid states influence the macroscopical behavior of the condensed state.

Quantum-mechanical calculations of clusters of the finite sizes will make it possible to determine characteristics of chemical bond and reactivity on the surface of small clusters, modeling by method of molecular dynamics will enable us to investigate the structural state of nanoparticles and kinetic features of proceeding reactions.

At the Chemical Faculty of Lomonosov Moscow State University a new approach to preparation of nanocrystalline heterogeneous catalysts, carriers, sorbents in sub- and supercritical environments is being developed at present. Available to the present time initial information testifies that properties of catalyst systems obtained in non-equilibrium sub- and supercritical environments differ essentially from properties of the same materials obtained by conventional methods. The developed technology opens wide prospects both for preparation of new nanocrystalline multicomponent heterogeneous catalysts and carriers in sub- and supercritical environments, and for modification of properties of traditional catalytic systems.

The Chemical Faculty of the Moscow State University has the necessary experimental equipment for research of physical and chemical and catalytic properties of catalysts with application of modern methods (Raman, UF and IK-spectroscopy, EPR spectroscopy, RFA, DTA, pulse microcatalytical method, adsorptive methods, an isotope exchange etc.). Within the framework of the given project at Chemical Faculty of the Moscow State University realization of a number of works on preparation in sub- and supercritical water nanocrystalline simple and complex oxide catalytic systems based on ZrO2, CeO2, TiO2 and full research of their physical and chemical and catalytic properties are planned.

In Institute of Metal Physics of Ural Branch of the Russian Academy of Sciences have developed various ways of nanocrystalline material synthesis, including gas-phase method of synthesis of metals and oxide compounds, mechanical alloying for creation of non-equilibrium nanomaterials on the different basis and other techniques.

For many years at IMP different experimental methods of investigation of structure and properties of materials such as X-ray structure analysis, neutron diffraction investigation, optical microscopic metallography, scanning and transmission electron microscopy, Moessbauer spectroscopy, annihilation of positrons, resistometry, tests of mechanical and magnetic properties of various materials and others have also been developed and used.

At the Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences the theory of diffusion to describe the abnormal phase transformations in nanocrystalline objects have been proposed and methods of computer modeling of atomic clusters for the description of cluster structure have been successfully developed.

The technology of detonation synthesis of ultra disperse diamonds developed in RFNC-VNIITF now allows to receive nanodiamond powders (TU 2-037-677-94) on industrial scale. Also in RFNC-VNIITF significant experience in chemical processing and modification of ultra disperse diamond powders is accumulated. It is expected, that at nanomaterial synthesis, containing nanoparticles of diamonds, properties of nanomaterials will be determined by chemical interaction, within the framework of the offered project development of technologies of detonation synthesis of ultra disperse diamond powders with various physical and chemical properties is provided, due to variation of chemical compound of detonating compositions, and also ways of purification of nanodiamonds obtained from impurities and directed methods of nanodiamond surface modification.

Lately works on research of physical and chemical properties of ultra disperse diamonds with application of modern analytical methods have been carried out as well. Bases of powder certification on their properties, which determine prospects of nanodiamond use in highly technological processes are created. Preliminary researches have shown that nanodiamonds as sorbents and catalysts can be used as powders, suspensions and composites. The functional groups formed at nanodiamond explosive synthesis provide an opportunity of their multiple use in cycles of sorption-regeneration. Continuation of the specified researches within the framework of the offered project will allow development of many directions having important practical value. Researches of opportunities of metal nanooxide fabrication by detonation method will also be carried out.

The proposed project should also leads to the results having significant commercial potential and support for conversion of RFNC-VNIITF from the military purposes to civil.

The scope of activities on the project is rather significant and includes, first of all, preparation of nanocrystalline materials with the help of detonation synthesis and water under sub- and supercritical conditions, chemical treatment of the obtained materials with the purpose of their modification, research of their superficial properties and study of questions of nanoparticle application for obtaining qualitative fillers of catalysts and sorbents.

In work the available equipment on explosive synthesis and chemical purification of diamond powders, a complex of conventional methods of research of physical and chemical and catalytic properties of materials and typical techniques of consumer characteristics test of samples from new materials will be used. Obtaining nanocrystalline oxide catalysts will be carried out on the flowing experimental installation allowing work with water under supercritical conditions.


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