Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
  • C01B21/0605—Binary compounds of nitrogen with carbon
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
  • C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/10—Solid density
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/32—Thermal properties
  • C01P2006/37—Stability against thermal decomposition
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31678—Of metal

Definitions

• the present invention relates to a process for the preparation of hydrogen-free carbon nitrides, in particular carbon nitrides of stoichiometry C 3 N 4 .
• the synthesis is carried out using
• Hydrogen-free starting materials namely inorganic isocyanates, which split off exclusively by thermal treatment of CO 2 .
• a way is proposed to provide carbonitrides inexpensively and efficiently, conveniently in the form of powders or coatings.
• Li + and Cl can be intercalated, Si catalyses graphitization, S is incorporated into the network, etc.
• the presence of hydrogen is to be considered a major impediment to the provision of a clean, reproducible, and defined carbonitride.
• halotriazines are reacted with substituted carbodiimides.
• hydrogen-containing samples are obtained which can be confirmed by means of elemental analysis or IR spectroscopy (bands at 3130 cm -1 and 3077 cm -1 ).
• the complete absence of halogens or silicon is not ensured.
• the product is sensitive to moisture, which can not be reconciled with a pure C 3 N 4 .
• only powders are obtained in this way, coatings are not accessible.
• the stated object has been achieved by a process for the preparation of a carbon nitride comprising the steps of (i) providing an i5 hydrogen-free, inorganic isocyanate and (ii) thermal treatment of the hydrogen-free, inorganic isocyanate, this by CO 2 -Abstratation in a Carbon Nitride is transferred.
• a carbon nitride can be obtained, which contains a proportion of hydrogen, based on the total weight of the
• Such a hydrogen-free carbon nitride is obtained according to the invention by using as starting material a hydrogen-free inorganic isocyanate. Furthermore, it was found according to the invention 30 that such hydrogen-free inorganic isocyanates are converted by thermal treatment under CO 2 -Abstratation in a carbon nitride. The absence of hydrogen in the product is thus ensured according to the invention by using hydrogen-free starting materials.
• the thermal treatment preferably takes place under protective gas, for example under argon or nitrogen. Only CO 2 is split off.
• the thermal treatment is preferably carried out at a temperature of up to 500 ° C., more preferably up to 470 ° C., even more preferably up to 450 ° C.
• the starting material is preferably at a temperature of at least 200 ° C., more preferably at least 300 0 C and even more preferably at least 400 0 C treated.
• a carbon nitride is a dense, three-dimensionally highly crosslinked inorganic macromolecule, which is preferably present in the form of a powder or a coating.
• the carbon nitride is composed exclusively of the atoms C and N.
• the stoichiometry is CNi, 3 3 (corresponding to C 3 N 4 ).
• the batch is preferably at certain intervals, for example every 6 h to 10 h, in particular every 8 h, cooled and crushed, eg mortared, in order to complete as much as possible guarantee.
• the total duration of the polycondensation is between 8 and 24 h.
• the condensation can be carried out up to a temperature of 500 0 C.
• a maximum of 475 ° C. and more preferably a maximum of 450 ° C. are preferred. Higher temperatures require the use of high-pressure conditions (p> 1 atm).
• the polycondensation may also be carried out simultaneously or in suitable solvent or dispersing agents, for example, high-boiling liquid solvents (preferably having a boiling point> 130 0 C), ionic liquids, molten salt, etc. However, this is not preferred.
• the polycondensation can be carried out under reduced pressure. But this is not preferred.
• the thermal treatment is carried out according to the invention preferably in the presence of a catalytic amount of mercury.
• the thermal treatment is particularly preferably carried out on a mercury contact under a protective gas atmosphere.
• a preferred embodiment of the reaction is the reaction of the pure, solid isocyanates at the mercury (Hg) contact under an atmosphere of dry nitrogen in a closed vessel (autoclave, glass ampoule, etc.).
• a further preferred embodiment consists in the dispersion of the isocyanate in an organic solvent, in particular in a polar aprotic solvent. Particularly preferred are as solvents
• the solvent is evaporated and compacted the deposited inorganic macromolecule, in particular under protective gas, such as N 2 .
• isocyanate-based educts Hydrogen-free representatives from which by CO 2 -Abstratation a solid of the empirical formula "C 3 N 4 " results This includes, for example, molecular, monomeric isocyanates, such as cyanogen isocyanate, tris isocyanato-s-triazine or resulting oligomers (associates) and macromolecular polyisocyanates (C 2 N 2 O) x or [(C 3 N 3 ) (NCO) 3 ] X, where x is an integer from 1 to 500, in particular from 3 to 100, preferably from 5 to 50, and most preferably from 10 to 40.
• molecular, monomeric isocyanates such as cyanogen isocyanate, tris isocyanato-s-triazine or resulting oligomers (associates) and macromolecular polyisocyanates (C 2 N 2 O) x or [(C 3 N 3 ) (NCO) 3 ] X, where
• polystyrene foam is preferred, the use of polymeric (C 2 N 2 O) x being particularly preferred.
• the starting materials are known to be sensitive to moisture and are thus handled under protective gas conditions for the provision and warranty as well as working with suitable shielding gases are known in the art.
• Suitable elements for this purpose are, for example, Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Cu, Ag, Au, Zn Isocyanates of the elements are accessible by known metathesis reactions. Preference is given to the reaction of CICN with elemental isocyanates, the reaction of CICN with AgNCO being particularly preferred.
• Another possibility is the thermal decomposition of CuNCO (copper isocyanate) or AgNCO (silver isocyanate) under vacuum conditions.
• CuNCO copper isocyanate
• AgNCO silver isocyanate
• Another possibility is the reaction of cyanamide with carbonylbisimidazole (Staabs reagent).
• [(C 3 N 3 ) (NCO) 3 ] x can be prepared by reacting C 3 N 3 Cl 3 (cyanuric chloride) with AgNCO 1 or by reacting C 3 N 3 (NHb) 3 (melamine) with oxalyl chloride or phosgene , Preference is given to the thermal decomposition of the corresponding acyl azide via thermally-induced Lossen rearrangement.
• the (polymeric) isocyanates represented in this way are moisture-sensitive compounds. They can be uniquely characterized by IR, UV, MS, NMR and elemental analysis. Particularly meaningful are the
• the preferred thermal process of this invention is to ensure an ideally complete CO 2 abstraction while inhibiting thermal fragmentation of the resulting carbonitride.
• the starting material isocyanate, for example, the yellow powder (C 2 N 2 O) x , advantageously in a reaction chamber, for example, in a heated glass ampule filled and this sealed under inert gas, for example nitrogen.
• a reaction chamber for example, in a heated glass ampule filled and this sealed under inert gas, for example nitrogen.
• inert gas for example nitrogen.
• a steel Autoclave can be used. The closed conditions prevent the sublimation of lower oligomers of the polyisocyanate and thus the change in the total stoichiometry. Since the CO 2 formed can not be removed efficiently, it is necessary to interrupt the thermolysis at least once, to open the reaction space and to allow the CO 2 to escape.
• the solid is then homogenized mechanically and again subjected to thermolysis under protective gas, for example under N 2 , in a closed system.
• protective gas for example under N 2
• the polycondensation is interrupted twice. Particularly preferably three times.
• the reaction, carried out at a maximum of 500 0 C, is completed after 24 h at the latest.
• the density of the resulting C 3 N 4 is 2.0 g / cm 3 to 2.3 g / cm 3 , especially 2.0 g / cm 3
• a catalytic amount of elemental mercury for example a drop of elemental mercury, is added to the isocyanate, in particular to the polyisocyanate (C 2 N 2 O) x , and the thermolysis is carried out as described.
• the drop is removed mechanically and the powder at 150 0 C to 250 0 C, in particular at 200 0 C, heated in vacuo.
• the density is 2.0 g / cm 3 to 2.3 g / cm 3 , in particular 2.3 g / cm 3 .
• the carbon nitride obtainable according to the invention thus preferably has a density of at least 2.0 g / cm 3 , more preferably of at least 2.1 g / cm 3 , even more preferably of at least 2.2 g / cm 3, and most preferably of at least 2 , 3 g / cm 3 .
• High density networks are a prerequisite for the preparation of crystalline variants of C 3 N 4 by high pressure techniques.
• the known amorphous CN networks have a density ⁇ 2.0 g / cm 3 .
• the inventive route represents a significant improvement in the synthesis of amorphous CN networks.
• the inorganic isocyanate is dispersed in a solvent of suitable polarity.
• a solvent of suitable polarity This is preferably carried out by polymerization of molecular isocyanates which oligomerize in suitable solvents and optionally form lyophilic colloids.
• the coating may be prepared by known methods, e.g. optionally by spraying, dipping or spinning, applied to substrates. Even brushing or brushing are possible.
• Suitable substrates are e.g. Glasses and ceramics as well as metals.
• the resulting brown powder is not appreciably hydrolysis-sensitive.
• the connection is an electrical insulator.
• a scanning electron micrograph shows the presence of an amorphous network with a macroporous microstructure.
• the elemental analysis gives the following values: [calculated for C 3 N 4 ]: C: 39.06 wt%, [39.14 wt%]; N: 59.21 wt%, [60.86 wt%]; O: 1.73 wt% [0.0 wt%]).
• the carbon nitride obtainable in accordance with the present invention preferably consists exclusively of C and N and is especially free of H, Hal (e.g., F, Cl, Br, J), Si, O, S, and alkali metals.
• the carbon nitride each has less than 2 wt .-%, in particular less than 1 wt .-%, preferably less than 0.1 wt .-% of each of these elements, based on the total weight, on.
• the C 3 N 4 can be thermally controlled to a lower carbonitride CN x (x ⁇ 1.33) or completely degraded to carbon. This is conveniently achieved by suitable heating under N 2 at temperatures> 450 0 C. This controlled degradation allows the realization of different CN X layers (0 ⁇ x ⁇ 1.33).
• the thermal decomposition preferably takes place between 500 D C and 600 0 C.
• the carbon nitride according to the invention in particular C 3 N 4 , at temperatures> 475 0 C controlled in a carbonitride of the form CN x , where x ⁇ 1, 33, are transferred and in particular controlled at temperatures> 475 0 C in pure carbon ,
• Figure 1 shows the IR spectrum of a C 3 N 4 polymer according to the invention, which was cured at 400 0 C.
• Cyanamide is reacted with Staabs reagent (carbonylbisimidazole) (1: 1) in acetonitrile. C 2 N 2 O is suspended in acetonitrile and imidazole. The solvents are removed in a dynamic vacuum.
• Staabs reagent carbonylbisimidazole
• Colorless C 2 N 2 O is dispersed in acetonitrile (1 g on 10 g of solvent). The result is a bright yellow clear solution.
• the solution is slowly concentrated until an orange viscous dispersion is formed. With suitable viscosity, the solution can be used for coating processes. Glass panes (cleaned and degreased) are dipped in the solution, wetted for 30 seconds and withdrawn at a controlled rate. The film is dried at RT under inert gas. If necessary, the coating process is repeated.
• the substrates coated in this way are slowly heated to 450 ° C. under flowing N 2 . This results in brown, grip-proof coatings.

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• 2009
  • 2009-01-19 DE DE200910005095 patent/DE102009005095A1/de not_active Withdrawn
• 2010
  • 2010-01-19 US US13/144,964 patent/US20120015194A1/en not_active Abandoned
  • 2010-01-19 WO PCT/EP2010/050574 patent/WO2010081910A2/de not_active Ceased
  • 2010-01-19 EP EP10701004A patent/EP2379448A2/de not_active Withdrawn
  • 2010-01-19 JP JP2011545763A patent/JP2012515135A/ja active Pending

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