METHOD OF NITROGEN FIXATION IN A PLASMA REACTOR

Abstract

A method of nitrogen fixation uses a synthesis gas formed of several gaseous reactants for the synthesis of a synthesis product; and a process gas formed by admixing a gaseous catalyst with the synthesis gas, with the molar proportion of the catalyst in the process gas no more than 33%. The mixing ratio for the several gaseous reactants in molar proportions is determined by: determining all atom types in the synthesis product; calculating the reciprocal of the total effective cross section (RTECS) for the ionization and excitation of atoms by electron impacts on the respective atom type; multiplying the RTECS values by the number of atoms of the respective atom type in the synthesis product; determining the mixing ratio of the reactants, in that the number of atoms of the atom types in the reactants corresponds approximately to the ratio of the multiplied RTECS values for the corresponding atom types.

Claims

1-12. (canceled)

13. A method of nitrogen fixation in a plasma reactor, wherein the method comprises: a) providing a synthesis gas formed of several gaseous reactants for the synthesis of a synthesis product, wherein the mixing ratio in molar proportions of the several gaseous reactants is determined as follows: determining all atom types in the synthesis product; calculating the reciprocal of the total effective cross section for the ionization and excitation of atoms by electron impacts on the respective atom type; multiplying the reciprocal total effective cross section values of the atom types by the number of atoms of the respective atom type in the synthesis product; determining the mixing ratio of the reactants, in that the number of atoms of the atom types in the reactants corresponds approximately to the ratio of the multiplied reciprocal total effective cross section values for the corresponding atom types; b) providing a process gas by admixing a gaseous catalyst with the synthesis gas, wherein the molar proportion of the catalyst in the process gas is not more than 33%; c) introducing the process gas into a plasma reactor for the synthesis of the synthesis product from the reactants; d) separating off the synthesis product; e) recycling the excess or residual reactants and the gaseous catalyst, with admixture of new reactants, in order to obtain the process gas with the mixing ratios according to steps a) and b); f) repeating steps c) to f).

14. The method according to claim 13, wherein the gaseous reactants are selected from the group consisting of hydrogen (H.sub.2), nitrogen (N.sub.2), oxygen (O.sub.2), and methane (CH.sub.4).

15. The method according to claim 14, wherein the gaseous reactants are selected from the group consisting of peroxyacetyl nitrate (PAN; CH.sub.3C(O)OONO.sub.2), peroxypropionyl nitrate (PPN; C.sub.2H.sub.5C(O)OONO.sub.2), peroxybenzoyl nitrate (PBZN; C.sub.6H.sub.5C(O)OONO.sub.2), peroxyacrylol nitrate (APAN; CH.sub.2CHC(O)OONO.sub.2), peroxyisobutyryl nitrate (PiBN; (CH.sub.3).sub.2CHC(O)OONO.sub.2), and peroxymethacryloyl nitrate (MPAN; CH.sub.2C(CH.sub.3)C(O)OONO.sub.2).

16. The method according to claim 13, wherein the gaseous catalyst is a gas that is not bound physically or chemically in the reaction products by the chemical reactions of the nitrogen fixation.

17. The method according to claim 13, wherein the gaseous catalyst is a noble gas.

18. The method according to claim 17, wherein the gaseous catalyst is argon, helium, neon, xenon, or radon.

19. The method according to claim 18, wherein the molar proportion of the noble gases argon, helium, neon, xenon and radon has the following values: TABLE-US-00008 argon 3-13% helium 6-25% neon 10-25% xenon 1-13% radon 1-13%.

20. The method according to claim 13, wherein the synthesis is performed at atmospheric pressure or more, preferably at a pressure of at least 2 bar, more preferably at least 5 bar.

21. The method according to claim 13, wherein the synthesis is performed at a temperature of at most 100 C.

22. The method according to claim 21, wherein the synthesis is performed at a temperature of 25 C. or less.

23. The method according to claim 13, wherein the synthesis is performed at a temperature of less than 0 C.

24. The method according to claim 13, wherein no solid-state catalyst is used.

25. The method according to claim 13, wherein the plasma is produced by means of direct-current discharges, high-frequency discharges, laser ionisation, radioactive radiation, pulsed direct-current discharges or combinations thereof.

26. The method according to claim 13, wherein the plasma is in thermal equilibrium in which the mean electron temperature is equal to the mean ion and neutral particle temperature.

27. The method according to claim 26, wherein the mean ion and neutral particle temperature has at least a slight thermal disequilibrium, in which the mean electron temperature is one order of magnitude higher than the mean ion and neutral particle temperature.

Description

BRIEF EXPLANATION OF THE FIGURES

[0052] The invention will be explained in greater detail below on the basis of practical examples in conjunction with the drawing(s), in which:

[0053] FIG. 1 shows a diagram of a method of nitrogen fixation.

WAYS OF CARRYING OUT THE INVENTION

[0054] FIG. 1 shows a diagram of a method of nitrogen fixation. In a first step 1, a synthesis gas is provided from several reactants E1, E2. In a second step 2, synthesis gas and a gaseous catalyst K are combined to form a process gas, with defined ratios of reactants and catalyst, and lastly are fed into a plasma reactor 3. The synthesis product S is synthesised in the plasma reactor and is then separated from the remaining process gases R in a step 4. The remaining process gases R, which contain reduced quantities of the reactants, are recycled and enriched with new synthesis gas so that a process gas with defined ratios of reactants and catalyst is provided again.

[0055] The mixing ratio in proportions of the reactants is determined as follows: [0056] a.1) determine all atom types of the synthesis product; [0057] a.2) calculate the reciprocal value of the total effective cross section for the ionisation and excitation of atoms by electron impacts (at approximately 5 eV) of the respective atom type; [0058] a.3) multiply the reciprocal total effective cross section values of the atom types by the number of atoms of the respective atom type of the synthesis product (weighted reciprocal total effective cross section of the atom types); [0059] a.4) determine the mixing ratio of the reactants by making the number of atom types of the reactants correspond approximately to the ratio of the multiplied or weighted reciprocal total effective cross section values for the corresponding atom types.

[0060] Example 1Ammonia synthesis (NH.sub.3) from N.sub.2 and H.sub.2

[0061] Step a.1: The synthesis product ammonia NH.sub.3 consists of the atom types N and H.

[0062] Step a.2: The total effective cross section (wq) [in 10{circumflex over ()}-20 m2] for N and H is wqN=14 and wqH=5, respectively. The reciprocal value (1/wq) is 1/wqN=0.07 and 1/wqH=0.2, respectively. The sum of the reciprocal values (1/wq) for all atoms of the respective atom types (N and H) of the synthesis product are for 11/wqN=0.07 and for 31/wqH=0.6 (step a.3). This results in an optimum mixing ratio for N.sub.2:H.sub.2 of 1:8.4 or an approximate mixing ratio of 1:9 (step a.4).

TABLE-US-00003 Step a.1: NH.sub.3 = N H H H Step a.2: wq [10.sup.20 m.sup.2] 14 5 5 5 1/wq 0.07 0.2 0.2 0.2 Step a.3: N 3*H 0.07 0.6 Step a.4 1/wq weighted and standardised 1 (N) 8.4 (H) according to atom type The reactants N.sub.2 and H.sub.2 have two N and two H, respectively, and are mixed correspondingly in the ratio according to step a.4 (N.sub.2:H.sub.2 = 1:8.4). Rounded mixing ratio of the reactants is then N.sub.2:H.sub.2 = 1:9

Example 2NO

[0063]

TABLE-US-00004 Step a.1: NO.sub.3 = N O Step a.2: wq [10.sup.20 m.sup.2] 14 0.003 1/wq 0.07 333 Step a.3: 1* N 1* O 0.07 333 Step a.4 1/wq weighted and standardised 1 (N) 4662 (0) according to atom type The reactants N.sub.2 and O.sub.2 have two N and two O, respectively, and are mixed correspondingly in the ratio according to step a.4 (N.sub.2:O.sub.2 = 1:4662).

Example 3NO.SUB.2

[0064]

TABLE-US-00005 Step a.1: NO.sub.2 = N O O Step a.2: wq [10.sup.20 m.sup.2] 14 0.003 0.003 1/wq 0.07 333 333 Step a.3: N 2* O 0.07 666 Step a.4 1/wq weighted and standardised 1 (N) 9333 (O) according to atom type The reactants N.sub.2 and O.sub.2 have two N and two O, respectively, and are mixed correspondingly in the ratio according to step a.4 (N.sub.2:O.sub.2 = 1:9333).

Example 4NO.SUB.3

[0065]

TABLE-US-00006 Step a.1: NO.sub.3 = N O O O Step a.2: wq [10.sup.20 m.sup.2] 14 0.003 0.003 0.003 1/wq 0.07 333 333 333 Step a.3: N 3* O 0.07 1000 Step a.4 1/wq weighted and 1 (N) 14000 (O) standardised according to atom type The reactants N.sub.2 and O.sub.2 have two N and two O, respectively, and are mixed correspondingly in the ratio according to step a.4 (N.sub.2:O.sub.2 = 1:14000).

Example 5HNO.SUB.3

[0066]

TABLE-US-00007 Step a.1: HNO.sub.3 = N H O O O Step a.2: wq [10.sup.20 m.sup.2] 14 5 0.003 0.003 0.003 1/wq 0.07 0.2 333 333 333 Step a.3: N H 3* O 0.07 0.2 1000 Step a.4 1/wq weighted and standardised according to atom type 1 (N) 2.8 (H) 14000 (O) The reactants N.sub.2; H.sub.2 and O.sub.2 have two N, two H and two O, respectively, and are mixed correspondingly in the ratio according to step a.4 (N.sub.2:H.sub.2:O.sub.2 = 1:2.8:14000).

LIST OF REFERENCE SIGNS

[0067] 1 mixing of the reactants to form a synthesis gas [0068] 2 provision of the process gas (synthesis gas and gaseous catalyst) [0069] 3 synthesis in the plasma reactor [0070] 4 separation of the synthesis product from the residual process gas [0071] 5 recycling of the residual process gas [0072] E1, E2 reactant [0073] K gaseous catalyst [0074] S synthesis product [0075] R residual process gas