REMOVAL OF OXYGEN FROM HYDROCARBON-CONTAINING GAS MIXTURES

Abstract

The invention relates to a method for removing oxygen from hydrocarbon-containing gas mixtures, characterized in that a hydrocarbon-containing gas mixture containing 50 vol % of one or more hydrocarbons, 2 to 10 vol % of oxygen, and possibly one or more gases from the group comprising nitrogen, noble gases, hydrogen, carbon dioxide, carbon monoxide, and water is introduced into an isothermally operated reactor, in which the oxygen contained in the hydrocarbon-containing gas mixture is at least partially converted into carbon dioxide and water in the presence of one or more catalysts, wherein the specifications in vol % relate to the total volume of the hydrocarbon-containing gas mixture introduced into the reactor and add up to 100 vol % in total.

Claims

1. A process for removing oxygen from hydrocarbon-containing gas mixtures, comprising the steps of: introducing a hydrocarbon-containing gas mixture containing ≧50% by volume of one or more hydrocarbons, from 2 to 10% by volume of oxygen and optionally one or more gases from the group consisting of nitrogen, noble gases, carbon dioxide, carbon monoxide and water into an isothermally operated reactor, and at least partly converting the oxygen present in the hydrocarbon-containing gas mixture into carbon dioxide and water in the presence of one of more catalysts, wherein the hydrocarbon-containing gas mixture does not contain any hydrogen and no hydrogen is added to the hydrocarbon-containing gas mixture and the one or more catalysts are selected from the group consisting of palladium/gold, platinum/gold and salts thereof, where the figures in % by volume are based on the total volume of the hydrocarbon-containing gas mixture introduced into the reactor and add up to a total of 100% by volume.

2. The process for removing oxygen from hydrocarbon-containing gas mixtures as claimed in claim 1, wherein no oxygen is introduced as further gas into the reactor.

3. The process for removing oxygen from hydrocarbon-containing gas mixtures as claimed in claim 1, wherein the gas mixture exiting from the reactor has a temperature that differs from the temperature of the hydrocarbon-containing gas mixture entering the reactor by ≦50° C.

4. The process for removing oxygen from hydrocarbon-containing gas mixtures as claimed in claim 1, wherein the hydrocarbon-containing gas mixture has a temperature of from ≦300° C. to ≧100° C. on entering the reactor.

5. The process for removing oxygen from hydrocarbon-containing gas mixtures as claimed in claim 1, wherein the gas mixture leaving the reactor has a temperature of from ≦350° C. to ≧100° C.

6. The process for removing oxygen from hydrocarbon-containing gas mixtures as claimed in claim 1, wherein the gas mixture leaving the reactor contains ≦1.5% by volume of oxygen, from 55 to 99.99999% by volume of one or more hydrocarbons and optionally one or more further gases selected from the group consisting of nitrogen, noble gases, hydrogen, carbon dioxide, carbon monoxide and water, where the figures in % by volume are based on the total volume of the respective gas mixture and add up to a total of 100% by volume.

7. The process for removing oxygen from hydrocarbon-containing gas mixtures as claimed in claim 1, wherein the degree of conversion of oxygen in the reactor is from 50 to 100 mol %.

8. The process for removing oxygen from hydrocarbon-containing gas mixtures as claimed in claim 1, wherein the gas mixture leaving the reactor contains from 85 to 99% by weight of the hydrocarbons which were present in the hydrocarbon-containing gas mixture to be purified which was introduced into the reactor.

9. The process for removing oxygen from hydrocarbon-containing gas mixtures as claimed in claim 1, wherein the gas mixture which has left the reactor is conveyed in its entirety or in part through a countercurrent heat exchanger in which a hydrocarbon-containing gas mixture which, after leaving the countercurrent heat exchanger, is fed to the reactor is heated.

10. The process for removing oxygen from hydrocarbon-containing gas mixtures as claimed in claim 1, wherein the gas mixture which has left the reactor is partly fed to further purification or utilization and the remaining part is added to one or more starting gas mixtures, wherein starting gas mixtures contain ≦15% by volume of oxygen, from 40 to 95% by volume of one or more hydrocarbons and optionally one or more further gases selected from the group consisting of nitrogen, noble gases, carbon dioxide, carbon monoxide and water, where the figures in % by volume are based on the total volume of the respective gas mixture and add up to a total of 100% by volume.

Description

EXAMPLE 1 (EX. 1)

[0052] The oxidative purification of the gas mixture was carried out in a plant as shown in FIG. 1. Data on the compositions, temperature and pressures of the gas mixture in the various parts of plant may be found in tables 1 and 2.

[0053] The gas mixture 1, i.e. a starting gas mixture, was mixed with the gas mixture 12, i.e. a recycle gas. The gas mixture 2 obtained in this way was passed through the countercurrent heat exchanger 3. Here, heat was transferred from the gas mixture 8 to the gas mixture 2. The gas mixture 4 which had been heated in this way was conveyed for further heating through the heat exchanger 5 operated by means of superheated steam and introduced as further-heated gas mixture 6 into the shell-and-tube reactor 7. The shell-and-tube reactor 7 was provided with a supported palladium-gold fixed-bed catalyst and was operated isothermally by means of evaporative water cooling.

[0054] The oxygen conversion in the shell-and-tube reactor 7 was 97 mol %, based on the oxygen introduced into the reactor.

[0055] The gas mixture 8 leaving the shell-and-tube reactor 7 was cooled during flow through the countercurrent heat exchanger 3 and was, to effect further cooling, conveyed through the heat exchanger 10 operated using cooling water as gas mixture 9. Water condensed out here.

[0056] 77 mol % of the gas mixture 11, based on the molar flow of gas mixture 11, was mixed as recycle gas 12 with the gas mixture 1 to give gas mixture 2 and thus recirculated into the process. The remaining 23 mol % of the gas mixture 11 was passed to utilization.

[0057] The purified gas mixture 13 had a composition identical to that of the gas mixture 11 and thus contained only traces of oxygen. The formation of any by-products such as carbon monoxide or ethylene oxide was not observed. Hydrogenation of ethylene to ethane also did not occur.

TABLE-US-00001 TABLE 1 Compositions of the gas mixtures of example 1: Ethane, Ethylene Oxygen methane Inerts.sup.a) [% by [% by Carbon dioxide [% by [% by volume] volume] [% by volume] volume] volume] Gas mixture 1 76.8 9.1 1.7 5.4 7.2 Gas mixture 2 78.2 2.2 6.6 5.5 7.5 Gas mixture 8 77.43 0.07 8.1 5.5 8.9 Gas mixture 11 78.53 0.07 8.2 5.6 7.6 .sup.a)Noble gases, nitrogen and water.

TABLE-US-00002 TABLE 2 Temperature and pressure of the gas mixtures of the examples: Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Gas mixture 1 Temperature [° C.] 25 50 30 25 25 Pressure [bar.sub.abs.] 10.5 10.5 9.5 10.5 10.5 Gas mixture 2 Temperature [° C.] 28 40 30 29 29 Pressure [bar.sub.abs.] 10.5 10.5 9.5 10.5 10.5 Gas mixture 4 Temperature [° C.] 175 175 175 190 190 Pressure [bar.sub.abs.] 10.45 10.45 9.45 10.45 10.45 Gas mixture 6 Temperature [° C.] 195 195 195 220 220 Pressure [bar.sub.abs.] 10.42 10.42 9.42 10.42 10.42 Gas mixture 8 Temperature [° C.] 215 205 215 230 230 Pressure [bar.sub.abs.] 10.32 10.32 9.32 10.32 10.32 Gas mixture 9 Temperature [° C.] 78 78 78 80 80 Pressure [bar.sub.abs.] 10.29 10.29 9.29 10.29 10.29 Gas mixture 11 Temperature [° C.] 25 25 25 25 25 Pressure [bar.sub.abs.] 10.29 10.29 9.29 10.29 10.29 Gas mixture 12 Temperature [° C.] 25 25 25 25 25 Pressure [bar.sub.abs.] 10.83 10.83 9.83 10.83 10.83 Gas mixture 13 Temperature [° C.] 25 25 25 25 25 Pressure [bar.sub.abs.] 10.83 10.83 9.83 10.83 10.83

EXAMPLE 2 (EX. 2)

[0058] Example 2 was carried out in a manner identical to example 1, with the following differences:

[0059] The gas mixture 1, i.e. the starting gas mixture, had a different composition, as indicated in table 3.

[0060] The oxygen conversion in the shell-and-tube reactor 7 was 84 mol %, based on the oxygen introduced into the reactor.

[0061] 47 mol % of the gas mixture 11, based on the molar flow of gas mixture 11, was recirculated as recycle gas 12 into the process. The remaining 53 mol % of the gas mixture 11 was passed to utilization.

[0062] Further information on the compositions, temperatures and pressures of the gas mixture at the various places of the process may be found in tables 2 and 3.

TABLE-US-00003 TABLE 3 Compositions of the gas mixtures of example 2: Ethane, Ethylene Oxygen methane Inerts.sup.a) [% by [% by Carbon dioxide [% by [% by volume] volume] [% by volume] volume] volume] Gas mixture 1 75.0 11.1 2.0 5.2 6.7 Gas mixture 2 75.8 6.5 5.0 5.4 7.3 Gas mixture 8 74.0 1.0 8.7 5.4 10.9 Gas mixture 11 76.8 1.0 9.0 5.6 7.6 .sup.a)Noble gases, nitrogen and water.

EXAMPLE 3 (EX. 3)

[0063] Example 3 was carried out in a manner identical to example 1, with the following differences:

[0064] The gas mixture 1, i.e. starting gas mixture, had a different composition, as indicated in table 4.

[0065] The oxygen conversion in the shell-and-tube reactor 7 was 95 mol %, based on the oxygen introduced into the reactor.

[0066] No recycle gas 12 was taken off from the gas mixture 11; i.e. the gas mixture 11 was passed in its entirety to utilization.

[0067] Further information on the compositions, temperatures and pressures of the gas mixture at the various places of the process may be found in tables 2 and 4.

TABLE-US-00004 TABLE 4 Compositions of the gas mixtures of example 3: Ethane, Ethylene Oxygen methane Inerts.sup.a) [% by [% by Carbon dioxide [% by [% by volume] volume] [% by volume] volume] volume] Gas mixture 1 81.2 5.0 1.6 5.2 7.0 Gas mixture 2 81.2 5.0 1.6 5.2 7.0 Gas mixture 8 79.6 0.3 4.8 5.2 10.1 Gas mixture 11 82.2 0.3 4.9 5.4 7.3 .sup.a)Noble gases, nitrogen and water.

EXAMPLE 4 (EX. 4)

[0068] Example 4 was carried out in a manner identical to example 1, with the following differences:

[0069] The gas mixture 1, i.e. the starting gas mixture, had a different composition, as indicated in table 5.

[0070] The heat exchanger 5 was operated using heat transfer oil. The shell-and-tube reactor 7 was provided with a supported palladium fixed-bed catalyst instead of the palladium-gold catalyst.

[0071] The oxygen conversion in the shell-and-tube reactor 7 was 40 mol %, based on the oxygen introduced into the reactor.

[0072] 92 mol % of the gas mixture 11, based on the molar flow of gas mixture 11, was recirculated as recycle gas 12 into the process. The remaining 8 mol % of the gas mixture 11 was passed to utilization.

[0073] Further information on the compositions, temperatures and pressures of the gas mixture at the various places of the process may be found in tables 2 and 4.

TABLE-US-00005 TABLE 5 Compositions of the gas mixtures of example 4: Carbon dioxide, Ethan, Ethylene Oxygen Carbon methane Inerts.sup.a) [% by [% by monoxide [% by [% by volume] volume] [% by volume] volume] volume] Gas mixture 1 77.7 8.2 1.7.sup.b) 5.4 7.0 Gas mixture 2 79.1 1.7 6.3 5.5 7.4 Gas mixture 8 78.9 1.0 6.8 5.5 7.8 Gas mixture 11 79.3 1.0 6.8 5.5 7.4 .sup.a)Noble gases, nitrogen and water; .sup.b)No carbon monoxide present in the starting gas 1.

EXAMPLE 5 (EX. 5)

[0074] Example 5 was carried out in a manner identical to example 4, with the following differences:

[0075] The gas mixture 1, i.e. the starting gas mixture, had a different composition, as indicated in table 5.

[0076] The oxygen conversion in the shell-and-tube reactor 7 was 40 mol %, based on the oxygen introduced into the reactor.

[0077] 91 mol % of the gas mixture 11, based on the molar flow of gas mixture 11, was recirculated as recycle gas 12 into the process. The remaining 9 mol % of the gas mixture 11 was passed to utilization.

[0078] Further information on the compositions, temperatures and pressures of the gas mixture at the various places of the process may be found in tables 2 and 4.

[0079] When a supported platinum fixed-bed catalyst was used instead of the palladium catalyst in the processes of examples 4 and 5, the results of examples 4 and 5 were essentially reproduced.

TABLE-US-00006 TABLE 6 Compositions of the gas mixtures of example 5: Carbon dioxide, Ethane, Ethylene Oxygen Carbon methane Inerts.sup.a) [% by [% by monoxide [% by [% by volume] volume] [% by volume] volume] volume] Gas mixture 1 80.9 5.0 1.7.sup.b) 5.2 7.2 Gas mixture 2 81.9 1.0 4.5 5.4 7.2 Gas mixture 8 81.7 0.6 4.7 5.4 7.5 Gas mixture 11 82.0 0.6 4.7 5.4 7.3 .sup.a)Noble gases, nitrogen and water; .sup.b)No carbon monoxide present in the starting gas 1.