Data processing: generic control systems or specific application – Specific application – apparatus or process – Chemical process control or monitoring system
Reexamination Certificate
2001-06-08
2004-09-28
Soderquist, Arlen (Department: 1743)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Chemical process control or monitoring system
C436S037000, C436S177000, C436S178000, C700S268000, C700S273000
Reexamination Certificate
active
06799089
ABSTRACT:
This invention relates to a process for estimating a property of use, for example the activity of a catalyst or the ability to hold a radio-element in a solid mineral matrix, of a material M
AB
whose active element is AB. The invention also relates to a process for determining the chemical affinity of an element or set of elements B for a matrix A, for example the affinity of a material for oxygen or sulfur-containing compounds or halogenated compounds. This more or less significant affinity makes it possible, for example, to identify the resistance of this material to corrosion by sulfur-containing compounds or halogenated compounds or by oxidation. Many other applications of these processes can be considered, some of which are explained below. More generally, the processes according to the invention therefore make it possible to select or to design new materials whose use produces the formation or the modification of at least one chemical bond that is characterized by a descriptor D
AB
or makes it necessary to prevent the formation of said bond.
PRIOR ART
In the present prior art, the selection or the design of materials for a determined application is considered only on an experimental basis according to the trial-and-error method. This practice is obviously long and expensive, and any process that allows a significant reduction of this search phase would offer a technical and economic advantage.
Numerous properties of use of the materials are to a large extent directly determined by the forces of chemical cohesion that are inherent to their composition: this is the case, for example, of mechanical properties (modulus of elasticity, resistance to rupture, hardness . . . ) of metals and their alloys, ceramics, construction materials, or else the case of solubilities of host elements, used for, for example, the capture of radioactive elements in mineral structures for storage purposes. These chemical cohesion forces will also determine all of the surface properties of the materials, of which one skilled in the art knows the technological importance: friction coefficient, resistance to wear, corrosion behavior, resistance to oxidation, adhesiveness, wettability, catalytic activity . . . .
The chemical cohesion forces also govern the local atomic structure of a material and thereby its electronic structure and all the physical properties (electronic, optical, magnetic . . . ) that are derived therefrom. The search for new high-temperature superconductive phases of electric current or else the search for new solid electrolytes with improved ionic conductivity for the production of more efficient fuel cells thus amount to searching for chemical compounds that have a special local organization (see, for example, J. B. Goodenough, Nature, Vol. 404, 20/04/2000, pp. 821-822, and cited references).
The practician in the search for new materials for a given application relies as much as possible today on the knowledge and the methods developed by the scientific discipline that is the chemistry of the solid: the latter quantifies the relative stabilities of the structures under given temperature and pressure conditions on the basis of the standard concept of formation enthalpy.
The standard formation enthalpies of a very large number of compounds have been measured experimentally and tabulated; they make it possible, for example, to construct so-called useful “phase” diagrams for the purpose of locating the areas of experimental conditions inside of which the structures of interest remain stable. These data and diagrams therefore have a limited value for the invention of new stable phases in an area of use that is specified at the very most so that one skilled in the art can therefore extrapolate by chemical analogy and intuition starting from known structure and composition phases.
For the purpose of guiding his action logically, the chemist that practices the synthesis of organic or inorganic compounds worked out early on the concept of chemical affinity and then, when the atomic structure of the material had been well established, the concept of interatomic force was developed. Modern theoretical chemistry has as its central object the elaboration of a quantitative and predictive theory of the chemical bond within atomic, molecular or crystalline structures.
Quantum physics provided the basis of a mathematical theory whose extreme precision is verified the better and in a broader range in proportion as the increase of power of electronic computers allows the digital resolution of constituent equations for increasingly more complex chemical compositions. These so-called “ab initio” calculation techniques, since they were unencumbered by prior knowledge of empirical data, were developed in less than two decades to the extent that it became conceivable to use them to predict the stability, the geometry and the physical and chemical properties of a chemical structure of given composition, prior to any laboratory attempt at synthesis.
This “design of computer-assisted material” is a very active methodological area of research but of which a very limited number of practical successes is known. These successes are confined to special cases, for example the development of a hydrocarbon reforming catalyst with a metallic nickel-based vapor and with increased stability by selective deposition of gold atoms on the surface (F. Besenbacher et al. Science, Vol. 279, 1913-1915, Mar. 20, 1998) or else the demonstration of a cathode composition that significantly improves the voltage and reduces the weight and the cost of a lithium battery (G. Ceder et al. Nature, Vol. 392, 694-696, Apr. 16, 1998). These recent cases of success rather exemplify an approach of verification by the calculation of a design of intuitive origin, confirmed a posteriori by experimental measurement.
The economic advantage of such paths is not clearly demonstrated currently, but anyone skilled in the art will impart to them a fundamental superiority in exploratory experimentation by trial and error, whose implementation will depend on the speed and the cost of the calculations to be used.
In this connection, the very fast growth over time of the calculation power at consistent cost, because of the advances in the technologies for integrating electronic circuits, suggests decisive breakthroughs in the near future. The process according to the invention unexpectedly anticipates in this direction, as a process for fast ab initio calculation of quantitative descriptors of the chemical bond in crystalline solids, that makes it possible to classify the latter by order of efficiency for a large number of applications of primary technological importance.
A strategy for exploratory searching for new materials that it is possible to consider as diametrically opposed to the “design of computer-aided materials” defined above consists of the “combinatorial chemistry” that appeared several years ago (see, for example, U.S. Pat. Nos. 5,959,297 and 5,985,356) and that makes sense only when combined with so-called “high-flow experimentation” techniques. In this case, the idea is to explore systematically by experiment a predefined space of compositions and synthesis conditions. The materials that result from these systematic combinations are prepared in very small quantities, just enough for tests that make possible a sorting according to the desired property or properties. The combinations that pass the tests make it possible to redefine a more restricted exploration space within which can be reiterated the combinatorial synthesis procedure and test for the purpose of refining the identification of combinations consistent with the initial target. The combination or combinations that are discovered are then synthesized in larger quantities to measure their properties of use with precision.
The “combinatorial chemistry” approach was recently the subject of considerable financial investments having led to significant technological developments. In this context, the computer technologies facilitate the management and the tracing of the propert
Institut Francais du Pe'trole
Millen White Zelano & Branigan P.C.
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