PROCESS FOR PREPARING AN ELECTRIDE COMPOUND

Abstract

A process for preparing an electride compound, comprising (i) providing a precursor compound comprising an oxidic compound of the garnet group; (ii) heating the precursor provided in (i) under plasma forming conditions in a gas atmosphere to a temperature of the precursor above the Httig temperature of the precursor, obtaining the electride compound.

Claims

1.-15. (canceled)

16. A process for preparing an electride compound, comprising (i) providing a precursor compound of the electride compound, wherein the precursor compound comprises an oxidic compound of the garnet group; (ii) heating the precursor compound provided in (i) under plasma forming conditions in a gas atmosphere to a temperature of the precursor compound above the Httig temperature of the precursor compound, obtaining the electride compound.

17. The process of claim 16, wherein according to (ii), heating the precursor compound under plasma forming conditions comprises heating the precursor compound in an electric arc.

18. The process of claim 16, wherein the oxidic compound of the garnet group according to (i) comprises aluminum and/or calcium.

19. The process of claim 16, wherein at least 90 weight-% of the precursor compound consist of an oxidic compound of the garnet group.

20. The process of claim 16, wherein providing the precursor compound according to (i) comprises (i.1) preparing a mixture comprising a source of calcium, a source of aluminum, and water; (i.2) optionally subjecting the mixture prepared in (i.1) to a hydrothermal treatment; (i.3) calcining the mixture prepared in (i.1), optionally the mixture obtained from (i.2), obtaining the precursor compound.

21. The process of claim 20, wherein the source of calcium is one or more of a calcium oxide, a calcium hydroxide, a hydrated calcium oxide, and a calcium carbonate, and the source of aluminum is one or more of an aluminum hydroxide including one or more of gibbsite, hydrargillite, bayerite, doyleite, nordstrandite, and gel-like amorphous aluminum hydroxide, an aluminum oxyhydroxide (AlO(OH)) including one or more of pseudo-boehmite, boehmite, diaspor, and akdalaite, and an aluminum oxide including one or more of gamma aluminum oxide, chi aluminum oxide, delta aluminum oxide, eta aluminum oxide, rho aluminum oxide and kappa aluminum oxide.

22. The process of claim 20, wherein according to (i.3), the mixture is calcined in a gas atmosphere, wherein the gas atmosphere comprises oxygen.

23. The process of claim 16, wherein the heating according to (ii) is carried out in an electric arc furnace which comprises a first electrode and a second electrode between which the electric arc is formed, wherein on the second electrode, the precursor compound to be heated is positioned, and wherein during heating according to (ii), the electrical power of the light arc between the first electrode and the second electrode is in the range of from 100 to 4000 W.

24. The process of claim 16, wherein according to (ii), the precursor compound is heated under plasma forming conditions for a period of time in the range of from 1 to 180 s.

25. The process claim 16, wherein heating the precursor compound under plasma forming conditions according to (ii) is carried out under oxygen (O.sub.2) removal conditions, wherein the oxygen removal conditions comprise physical oxygen removal conditions and/or chemical oxygen removal conditions.

26. The process of claim 25, wherein the chemical oxygen removal conditions comprise a gas atmosphere according to (ii) which comprises an oxygen reducing gas, and wherein the gas atmosphere according to (ii) comprises a gas which is ionizable under the plasma forming conditions according to (ii).

27. The process of claim 25, wherein the physical oxygen removal conditions comprise (ii.1) heating the precursor compound provided in (i) in the gas atmosphere under plasma forming conditions for a period of time delta.sub.1t, wherein the gas atmosphere comprises a gas which is ionizable under the plasma forming; (ii.2) at least partially removing the gas atmosphere after the period of time delta.sub.1t and providing a fresh gas atmosphere comprising a gas which is ionizable under the plasma forming conditions; (ii.3) further heating of the precursor compound obtained from (ii.2) in the fresh gas atmosphere under plasma forming conditions for a period of time delta.sub.2t.

28. An electride compound, obtained by the process according to claim 16.

29. An electride compound exhibiting an XRD pattern comprising a 211 reflection and a 420 reflection, wherein the intensity ratio of the 211 reflection relative to the 420 reflection is greater than 1:1, and/or exhibiting an EPR spectrum comprising resonances in the range of from 335 to 345 mT.

30. Use of an electride compound according to claim 28 as a catalyst or a catalyst component.

Description

SHORT DESCRIPTION OF THE FIGURES

[0240] FIG. 1 shows a schematic drawing illustrating the general principle of the electric arc furnace described in Reference Example 1.1. In particular, [0241] 1 stands for the electric furnace recipient [0242] 2 stand for the tungsten electrode (cathode) [0243] 3 stands for the water-cooled copper anode [0244] 4 shows the distance between cathode and anode (about 20 mm) [0245] 5 shows the diameter of the anode (101 mm) [0246] 6 shows the height of the tungsten electrode (63 mm) [0247] 7 shows the height of the housing (158 mm) [0248] 8 stands for the housing

[0249] FIG. 2 shows a schematic drawing illustrating the general principle of the electric arc furnace described in Reference Example 1.1. In particular, [0250] 1 stands for the electric furnace recipient [0251] 2 shows the connection to a vacuum pump [0252] 3 shows the connection to a gas reservoir (e.g. for Ar or for Ar/H.sub.2) [0253] 4 shows an air vent

[0254] FIG. 3 shows the linear correlation of the apparatus settings (intensity levels) and the corresponding electric power for two different gas atmospheres in the electric arc furnace.

[0255] FIG. 4 shows the XRD pattern of the oxidic compound prepared according to Example 1.

[0256] FIG. 5 shows the XRD pattern of the electride compound prepared according to Example 3.2.

[0257] FIG. 6 shows the XRD pattern of the electride compound prepared according to Example 3.3.

[0258] FIG. 7 shows the EPR spectrum of the electride compound prepared according to Example 3.3.

[0259] FIG. 7a shows the Kubelka-Munk transformed absorption spectrum of the electride compound prepared according to Example 3.3.

[0260] FIG. 8 shows the XRD pattern of the gamet compound prepared according to Example 4.1.

CITED PRIOR ART

[0261] Y. Nishio, K. Nomura, M. Miyakawa, K. Hayashi, H. Yanagi, T. Kamiya, M. Hirano und H. Hosono, Fabrication and transport properties of 12CaO.7Al2O3 (C12A7) electride nanowire, Phys. Stat. Sol. (A) (Physica Status Solidi (A)), 2008, pp 2047-2051 [0262] J. L. Dye, Electrons as Anions, Science, 2003, pp 607-608 [0263] J. L. Dye, Electrides: early examples of quantum confinement, Acc Chem Res, 2009, pp 1564-1572 [0264] US 2006/0151311 A1 [0265] US 2009/0224214 A1 [0266] US 2015/0217278 A1 [0267] E. S. Grew et al., American Mineralogist, vol. 98, 2013, pp 785-211 [0268] Matsuishi, S.; Toda, Y.; Miyakawa, M.; Hayashi, K.; Kamiya, T.; Hirano, M.; Tanaka, I.; Hosono, H. Science, 2003, 301, pp 626