DE10048472A1 - Novel concept for energy generation via an inorganic nitrogen cycle, starting from the basic material sand and producing higher silanes - Google Patents

Abstract

The invention relates to a novel energy concept that relates to an artificial silicon-nitrogen cycle and that constitutes the complement to the natural carbon-oxygen cycle. Pure silicon is produced from sand using solar energy. By repeated Müller-Rochow synthesis with silylchlorides the silicon is converted to higher silanes. The silylchlorides used are either silicons derived from chemical wastes or are economically produced from monosilanes or disilanes. They are mixed with silicon powder and combusted with air to give H2O and silicon nitride Si3N4, thereby generating power. The silicon nitride is converted to ammonia NH3 under alkaline conditions, thereby producing silicates. Part of the NH3 is converted to follow-on products, the major portion however is combusted with air to give H2O and N2, thereby generating power. The N2 cycle is thereby closed.

Description

Silicon is located directly below carbon in the periodic table of the chemical elements and therefore resembles it. However, the hydrogen compounds of silicon have some differences from the hydrocarbons. Friedrich Wöhler discovered the silicon homologue of methane CH ₄ , the monosilane SiH ₄ , around the turn of the century. At the beginning of the 20th century, Prof. Alfred Stock, Karlsruhe, could represent the longer-chain homologues of the hydrocarbons ethane, propane and butane, i.e. disilane Si ₂ H ₆ , trisilane Si ₃ H ₈ , and tetrasilane n-Si ₄ H ₁₀ however, all are self-igniting in air.

In 1951, silane research began under Prof. Franz Fehér in Cologne. At the beginning of the 1970s, his assistant Peter Plichta succeeded for the first time in producing the hitherto unknown so-called higher silanes from pentasilane Si ₅ H ₁₂ to decasilane Si ₁₀ H ₂₂ (German patent 21 39 155 (1976)). It was shown that - contrary to previous assumptions - higher silanes do not become more unstable with increasing chain length, on the contrary, they become more and more stable, so that, for example, heptasilane (n-Si ₇ H ₁₆ ) is no longer self-igniting at room temperature! Higher silanes are handling-safe, non-toxic, diesel-like and therefore pumpable liquids.

Silanes can be used as energy-generating fuels (German Pa tent 42 15 835 (1994); U.S. Patent 5,775,096 (1998)).

The following is the combustion of hydrocarbons with the Combustion of silicon hydrides compared.

As is well known, when hydrocarbons are burned, the hydrogen and carbon components react only with the 20% oxygen component in the air:

H ₂ + ½O ₂ → H ₂ O and C + O ₂ → CO ₂

disadvantage

The nitrogen content in the air, which is 80%, remains unaffected used, the respiratory poison carbon dioxide is also created.

In contrast to carbon, silicon has the property of forming an extremely stable nitride compound, the industrially known silicon (tetra) nitride Si ₃ N ₄ :

3Si + 2N ₂ → Si ₃ N ₄ + 750 kJ

The technical representation of Si ₃ N ₄ has so far been carried out by the action of molecular nitrogen on Si powder at 1100-1400 ° C. Experiments at Wacker-Chemie AG have shown that even cold (approx. 200 ° C) nitrogen reacts or ignites with silicon (catalytically) (conference "Silicon for the Chemical Industry V", May 29-June 2, 2000, Tromso (Norway), lecture by Dr. G. Tamme: "Silicon Cyclone Dust and Copper Oxide in the Direct Process, a Dange rous Mixture?")

The following reactions are possible in an air breathing engine:

3Si + 2N ₂ → Si ₃ N ₄ + 750 kJ (I)

H ₂ + ½O ₂ → H ₂ O (II)

Si + O ₂ → SiO ₂ (III)

benefits

The atmospheric nitrogen can be used in the combustion of silanes be exploited!

The goal of burning silicon hydride is to reduce the hydrogen content in a stoichiometric combustion chamber with atmospheric oxygen (as in Hydrocarbons), but also the nitrogen content of the air Implement silicon. For the complete combustion of the supplied air stick To achieve this, one could use silicon powder dispersed in silane gasoline add (German Patent 196 12 507 (1997); US Patent 5,996,332 (1999)). The Si Lan / silicon mixture remains pumpable.

If, for example, n-heptasilane Si ₇ H ₁₆ (bp 226.8 ° C, density 0.859 g / cm ³ ) is selected, the following stoichiometric combustion of a normal air mixture of 20% O ₂ and 80% N ₂ results:

16H + 4O ₂ → 8H ₂ O

7Si + 16N ₂ + an additional 17 dispersed Si → 8Si ₃ N ₄

The equations show that the amount of air drawn in is actually in 100% yield can be used as an oxidizing agent. The I. A. inert Gas nitrogen acts as an oxidizer. This reaction also does not produce any a lot of breathing poison, but in addition to water only silicon nitride, that even more can be collected or filtered.  

In order to be able to carry out such a combustion in practice, A jet turbine has already been developed, which injects the extremely hot combustion gases 2 consecutive combustion chambers processed so that a shaft can be driven (German Patent 196 12 507 (1997); US Patent 5,996,332 (1999)). This turbine serves as a replacement for conventional explosion engines. In addition, an air-breathing rocket engine (i.e. without an oxidation tank!) known to be used in supersonic aircraft and space planes (German Patents 44 37 524 (1996) and 44 39 073 (1996)).

With the patent applications dated September 18, 2000 (AZ 100 46 037.2) and 09/29/2000 is known, Higher silanes from the repeated application of the changed Müller-Rochow synthesis (i.e. with silyl chlorides instead of methyl chlori to manufacture the) inexpensively.

This creates the prerequisites for silanes to be the central stock to make part of the future energy supply.

The present invention has for its object to describe a newly discovered chemical, inorganic cycle in which Siliciumdi oxide, the main constituent of the earth's crust, is first converted into pure silicon with the help of sunlight. Higher silanes obtained therefrom are then burned with atmospheric nitrogen, producing silicon nitride Si ₃ N ₄ . This Si ₃ N ₄ is converted basicly into ammonia NH ₃ . This also produces silicates, which, however, do not have to be fed back into the cycle since SiO _{2 is} available free of charge. When burning NH ₃ ent is in turn generating energy N ₂ , so that the nitrogen cycle is closed ge.

These individual steps are known in principle, they are in the Che manuals or are already patented or patent pending.

However, the present invention describes the idea of the individual be known steps to combine a cyclical system that the natural Carbon cycle resembles.

The conventional carbon cycle consists of the dualism or symbiosis of the organisms of plants on the one hand and living things on the other: With the help of sunlight, CO _{2 is} assimilated in plants by photosynthesis and O _{2 is} generated. The hydrocarbon products produced in the plants serve as food for animals and humans. The oxygen generated by the plants is breathed in by animals and humans, producing energy. This creates CO ₂ , which the plants need to survive.

In the millions of years of evolution, an equilibrium has been established that keeps the proportion of carbon dioxide in the atmosphere constant. However, this balance has increasingly faltered with the beginning of the industrial age. The ever increasing industrial CO ₂ emissions that threaten the entire ecosystem worldwide go hand in hand with the increasingly scarce crude oil reserves.

The object of the present invention is also a way out of this to show an increasingly acute situation.  

The advantage of using silanes as fuels is the unlimited availability of the basic material silicon in contrast to the very limited crude oil deposits. 25% of the earth's crust is made of silicon. Sand e.g. B. has the chemical formula SiO ₂ .

(I) The high demand for pure silicon can be met by reducing the sand (SiO ₂ ) with coal and solar power in hot desert countries to pure silicon on site in an electric arc furnace. Ge exactly how the sunlight in the plants ensures that electrons can be used for CC formation, so in the inorganic cycle described here, electricity is generated using solar cells made of silicon, which is required for the production of pure silicon in the electric arc furnace.

The resulting pure CO ₂ can be used to produce the organic basic chemical methanol so that it does not get into the atmosphere. Methanol is a refined form of coal. The hydrogen required to refine CO ₂ to methanol CH ₃ OH according to the formula CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O is generated by electrolysis, the electricity required for this also coming from the solar cells.

(II) In the next step, the silicon is modified by the Müller-Rochow synthesis with silyl chlorides Higher silanes produced. in this connection Ideally, as silyl chlorides, industries that are otherwise expensive to dispose of Cases from silicone chemistry such as methylchlorodisilanes are used. Alterna The silyl chlorides are obtained by chlorination in the case of acidic decomposition of magnesium silicide in large quantities of mono- and disilane.

(III) In the third step, the higher silanes are burned with the addition of dispersed silicon powder with atmospheric air (20% O ₂ ; 80% N ₂ ) to water H ₂ O and silicon nitride Si ₃ N ₄ . This silicon nitride Si ₃ N _{4, which} is also required in industry, is a gray-white, completely non-toxic dust that only melts with decomposition at temperatures around 1900 ° C.

(IV) Si ₃ N ₄ can be dissolved in alkalis and converted into NH ₃ ammonia. The resulting silicates are harmless, but do not have to be recycled because sand SiO _{2 is present} in abundance. Parts of the ammonia can be used to make artificial fertilizers.

(V) In the next step, however, the majority should be burned with atmospheric air, again with high heat emission, to nitrogen N ₂ and water H ₂ O As a result, nitrogen comes back into the atmosphere, which is then available again for the combustion of the higher silanes.

The reactions described above result in an interaction of a novel chemical cycle ( Fig. 1).

The silicon-nitrogen cycle described represents a completely new kind Energy cycle. This cycle is the artificial counterpart to the natural one Carbon-oxygen cycle. With the introduction of silicon rectifiers, Transistors, diodes, memory chips etc. in physics and with silicone oils and - Plastics in chemistry has announced the age of silicon with which presented cycle it finally prevails. It must be emphasized that the energy released by the described cycle ultimately comes from the Sunlight comes just like in photosynthesis.

The 5 steps of the cycle are not fundamentally new, the Ge However, velvet idea represents something completely new.

Claims (5)

1. A method for generating energy in the course of an inorganic nitrogen-silicon cycle, characterized in that the following steps are carried out cyclically:

• a) Production of pure silicon by reduction of sand SiO ₂ with coal in an electric arc furnace with production of pure CO ₂ .
• b) Generation of higher silanes Si _x H _{2x + 2} by repeated application of the modified Müller-Rochow synthesis with silyl chlorides.
• c) Energy generation by stoichiometric combustion of the silanes with dispersed silicon powder in air N ₂ / O ₂ with the formation of H ₂ O and Si ₃ N ₄ , for example in engines in a wide variety of vehicles.
• d) Collecting or filtering the Si ₃ N ₄ dust and basic conversion to ammonia NH ₃ with the formation of silicates (silicon oxides).
• e) Further processing of the NH ₃ in small parts to synthetic fertilizer, but in large part combustion of the NH ₃ with air with the formation of and H ₂ O and N ₂ .

2. The method according to claim 1a., Characterized in that for the light electric furnace is generated in solar cells. 3. The method according to claim 1a., Characterized in that the pure CO ₂ resulting in the re reduction of the silicon dioxide is refined to methanol CH ₃ OH. 4. The method according to claim 3, characterized in that the hydrogen H ₂ required for refining the CO ₂ to methanol is generated by electrolysis with the aid of solar power. 5. The method according to claim 1b., Characterized in that the silyl chlorides can be obtained by chlorination with HCl from mono- and disilane the acidic decomposition of magnesium silicide in large quantities.