Abstract
The present invention relates to a continuous process for preparing chlorine and a production unit for carrying out said process. The present invention further relates to a use of said production unit for the continuous production of chlorine.
Claims
1-17. (canceled)
18. A continuous process for preparing chlorine, comprising (i) providing a gas stream G1 comprising oxygen (O.sub.2) and hydrogen chloride (HCl); (ii) passing the gas stream G1 into a reaction zone Z, bringing the gas stream G1 into contact with a catalyst comprised in said reaction zone Z, obtaining a gas stream GP comprising chlorine (Cl2) and one or more of O.sub.2, H.sub.2O and HCl, and removing the gas stream GP from said reaction zone Z; (iii) dividing the gas stream GP, obtaining at least two gas streams comprising a gas stream G2 and a gas stream GR, G2 and GR having the same chemical composition as GP, wherein the ratio of the mass flow f(GR) of the gas stream GR relative to the mass flow f(G2) of the gas stream G2, f(GR):f(G2), is in the range of from 0.1:1 to 20:1; wherein during standard operation mode of the continuous process, providing the gas stream G1 according to (i) comprises preparing G1 as a mixture comprising at least two gas streams, said at least two gas streams comprising the gas stream GR and j gas streams G0(k) with k=1, . . . j, wherein the j gas streams G0(k) in total comprise oxygen (O.sub.2) and hydrogen chloride (HCl) and wherein j is in the range of from 1 to 3.
19. The process of claim 18, wherein j is 1 or 2.
20. The process of claim 18, wherein the reaction zone Z is an adiabatic reaction zone.
21. The process of claim 18, wherein f(GR):f(G2) is in the range of from 1:1 to 10:1.
22. The process of claim 21, wherein f(GR):f(G2) is in the range of from 3.2:1 to 5:1.
23. The process of claim 18, wherein during standard operation mode of the continuous process, providing the gas stream G1 according to (i) comprises preparing G1, as a mixture comprising three gas streams GR, G0(1) and G0(2), G0(1) comprising oxygen (O.sub.2) and G0(2) comprises hydrogen chloride (HCl), which comprises combining the gas stream G0(1) with the gas stream G0(2), and admixing the gas stream GR with the combined gas streams G0(1) and G0(2).
24. The process of claim 23, wherein, according to (i), admixing the gas stream GR with the combined two gas streams G0(1) and G0(2) is performed in a mixing device, wherein the mixing device is an ejector, a static mixer or a dynamic mixer.
25. The process of claim 23, wherein the combined gas streams G0(1) and G0(2) have a pressure P0 and the gas stream GR has a pressure PR, wherein P0>PR.
26. The process of claim 18, wherein the recycle ratio is the ratio of the mass flow f(GR) of the gas stream GR relative to the mass flow f(GP) of the gas stream GP, f(GR):f(GP), which is in the range of from 0.2:1 to 0.95:1; wherein the gas stream GP has a temperature T(GP) of at most 450? C.
27. The process of claim 18, wherein (ii) further comprises passing the gas stream GP removed from the reaction zone Z in a heat exchanger, obtaining a cooled gas stream GP having a temperature in the range of from 200 to 350? C.
28. The process of claim 27, wherein f(GR):f(G2) is in the range of from 3.2:1 to 5:1.
29. The process of claim 18, wherein during standard operation mode of the continuous process, providing the gas stream G1 according to (i) comprises preparing G1, as a mixture comprising a liquid stream L and three gas streams GR, G0(1) and G0(2), G0(1) comprising oxygen (O.sub.2) and G0(2) comprises hydrogen chloride (HCl), wherein the liquid stream L comprises hydrogen chloride (HCl) and water, which comprises combining the gas stream G0(1) with the gas stream G0(2) and admixing the gas stream GR with the combined gas streams G0(1) and G0(2) and the liquid stream L; or wherein during standard operation mode of the continuous process, providing the gas stream G1 according to (i) comprises preparing G1, as a mixture comprising a liquid stream L and three gas streams GR, G0(1) and G0(2), G0(1) comprising oxygen (O.sub.2) and G0(2) comprises hydrogen chloride (HCl), wherein the liquid stream L comprises hydrogen chloride (HCl) and water, which comprises combining the gas stream G0(1) with the gas stream G0(2), admixing the gas stream GR with the combined gas streams G0(1) and G0(2), and subsequently adding the liquid stream L to the admixed gas streams.
30. The process of claim 29, wherein the liquid stream L has temperature T(L) in the range of from 10 to 60? C.
31. The process of claim 18, further comprising, after (iii), passing the gas stream GR through a return means R prior to preparing G1 according to (i), during standard operation mode of the continuous process, in an ejector.
32. The process of claim 18, wherein the catalyst is selected from the group consisting of a Ru-based catalyst, a Ce-based catalyst, a Cu-based catalyst and a mixture of two or more thereof.
33. A production unit for carrying out the process according to claim 18, the unit comprising a reaction zone Z comprising an inlet means for passing the gas stream G1 into Z; a catalyst; a reaction means for bringing into contact the gas stream G1 with said catalyst; an outlet means for removing the gas stream GP from Z; a stream dividing device S for dividing the gas stream GP in at least two streams comprising a gas stream GR and a gas stream G2; a means for passing the gas stream GP into said device S; a means M for preparing G1 as a mixture comprising GR and j gas streams G0(k) with k=1, . . . j, wherein j is in the range of from 1 to 3; a return means R for passing the gas stream GR exiting from S to said means M for preparing G1.
34. A process for preparing phosgene comprising preparing chlorine according to the process of claim 18; reacting the obtained chlorine with carbon monoxide in the presence of a catalyst, in gas phase, obtaining phosgene.
Description
DESCRIPTION OF THE FIGURES
[0197] FIG. 1 is a schematic representation of a production unit according to embodiments of the invention. The production unit comprises a reaction zone Z comprising an inlet means, such as a pipe, for passing the gas stream G1 into Z and a reaction means for bringing into contact the gas stream G1 with a catalyst (not shown), preferably an adiabatic reactor, namely a reactor wherein the reaction is operated adiabatically. The temperature of gas stream G1 is of 280? C. The reactor is a reactor, preferably an adiabatic fixed-bed reactor. The maximum gas stream temperature in the reactor and at the outlet of the reactor was 390? C. Further, the reaction zone Z comprises an outlet means, for example a pipe, for removing the gas stream GP from Z. The gas stream GP comprises chlorine and one or more of HCl, H.sub.2O and O.sub.2. The production unit further comprises a heat exchanger H for cooling the gas stream GP prior to be divided in a stream dividing device in two streams, a gas stream GR and a gas stream G2, a means, such as a pipe, for passing the gas stream GP into the stream dividing device not represented in this figure. The gas streams G2 and GR have respectively the same chemical composition as GP. The amount of HCl in G2 related to the feed flow of HCl in G0 gives a HCl conversion of about 88%. The production unit further comprises a means M, preferably an ejector driven by G0, for admixing the gas stream G0 with the gas stream GR comprising an inlet means, such as a pipe, for feeding the gas stream G0 into M and a means for feeding the gas stream GR into M. The gas stream G0 consists of HCl and O.sub.2. To obtain G0 two gas streams, G0(1) consisting of HCl and G0(2) consisting of O.sub.2 were combined, these streams are not shown here. The recycle gas stream GR is sucked in the ejector M. The recycle ratio is the ratio of the mass flow f(GR) of the gas stream GR relative to the mass flow f(GP) of the gas stream GP, f(GR):f(GP), which was of about 0.8:1. The production unit further comprises a return means R, a return pipe, for passing the gas stream GR exiting from the stream dividing device to said means M. [0198] FIG. 2 is a further schematic representation of a production unit according to embodiments of the invention. The production unit comprises a reaction zone Z comprising an inlet means, such as a pipe, for passing the gas stream G1 into Z and a reaction means for bringing into contact the gas stream G1 with a catalyst C, preferably an adiabatic reactor, namely a reactor wherein the reaction is operated adiabatically. The temperature of gas stream G1 is of 280? C. The reactor is an adiabatic fixed-bed reactor. The maximum gas stream temperature in the reactor and at the outlet of the reactor was 390? C. Further, the reaction zone Z comprises an outlet means, for example a pipe, for removing the gas stream GP from Z. The gas stream GP comprises chlorine and one or more of HCl, H.sub.2O and O.sub.2. The production unit further comprises a stream dividing device dividing the gas stream GP in two streams, a gas stream GR and a gas stream G2, a means, such as a pipe, for passing the gas stream GP into the stream dividing device not represented in this figure. The gas streams G2 and GR have respectively the same chemical composition as GP. The amount of HCl in G2 related to the feed flow of HCl in G0 gives a HCl conversion of about 86.2%. The production unit further comprises a means M, preferably an ejector driven by G0, for admixing the gas stream G0 and a liquid stream L comprising water and HCl liquid stream L with the gas stream GR comprising two inlet means, such as a pipe, for feeding the gas stream G0 and the liquid stream L into M and a means for feeding the gas stream GR into M. The gas stream G0 consists of HCl and O.sub.2 and has a temperature of 20? C. To obtain G0 two gas streams, G0(1) consisting of HCl and G0(2) consisting of O.sub.2 were combined, these streams are not shown here. The liquid stream L consisting of hydrochloric acid in water (30 wt. % HCl) has also a temperature of 20? C. The recycle gas stream GR is sucked in the ejector M. The recycle ratio is the ratio of the mass flow f(GR) of the gas stream GR relative to the mass flow f(GP) of the gas stream GP, f(GR):f(GP), which was of about 0.78:1. The production unit further comprises a return means R, a return pipe, for passing the gas stream GR exiting from the stream dividing device to said means M.
[0199] FIG. 3 is a further schematic representation of a production unit according to embodiments of the invention. The production unit comprises a reaction zone Z comprising an inlet means, such as a pipe, for passing the gas stream G1 into Z and a reaction means for bringing into contact the gas stream G1 with a catalyst C, preferably an adiabatic reactor, namely a reactor wherein the reaction is operated adiabatically. The minimum temperature of G1 is of at least 200? C., preferably at least 250? C. The reactor is an adiabatic fixed bed reactor. The maximum gas stream temperature in the reactor and at the outlet of the reactor was set to at most 400? C. Further, the reaction zone Z comprises an outlet means, for example a pipe, for removing the gas stream GP from Z. The gas stream GP comprises chlorine and one or more of HCl, H.sub.2O and O.sub.2. The production unit further comprises a stream dividing device for dividing the gas stream GP in two streams, a gas stream GR and a gas stream G2, a means, such as a pipe, for passing the gas stream GP into the stream dividing device not represented in this figure. The gas streams G2 and GR have respectively the same chemical composition as GP. The amount of HCl in G2 related to the feed flow of HCl in G0 gives preferably a HCl conversion of from 60-100%. The production unit further comprises a means M, preferably an ejector, for admixing the gas stream G0 with the gas stream GR comprising an inlet means, such as a pipe, for feeding the gas stream G0 into M and a means for feeding the gas stream GR into M. The gas stream G0 consists of HCl and O.sub.2. To obtain G0 two gas streams, G0(1) consisting of HCl and G0(2) consisting of O.sub.2 were combined, these streams are not shown here. The recycle gas stream GR is passed through a heat exchanger H prior to being sucked in the ejector M. The recycle ratio is the ratio of the mass flow f(GR) of the gas stream GR relative to the mass flow f(GP) of the gas stream GP, f(GR):f(GP), which is in the range of from 0.2:1 to 0.95:1, preferably in the range of from 0.5:1 to 0.9:1, more preferably in the range of from 0.7:1 to 0.85:1. The production unit further comprises a return means R, a return pipe, for passing the gas stream GR exiting from the stream dividing device to heat exchanger H and from heat exchanger H to said means M.
[0200] FIG. 4 is a further schematic representation of a production unit used in Comparative Example 1 (not according to the invention). The production unit comprises a reaction zone Z comprising an inlet means, such as a pipe, for passing the gas stream G0 into Z and a reaction means for bringing into contact the gas stream G0 with a catalyst (not shown), preferably an adiabatic reactor, namely a reactor wherein the reaction is operated adiabatically. The temperature of gas stream G0 is of 280? C. The reactor is an adiabatic fixed-bed reactor. The maximum gas stream temperature in the reactor and at the outlet of the reactor was 665? C. Further, the reaction zone Z comprises an outlet means, for example a pipe, for removing the gas stream GP from Z. The gas stream GP comprises chlorine and one or more of HCl, H.sub.2O and O.sub.2. The production unit further comprises a heat exchanger H for cooling the gas stream GP. The amount of HCl in GP related to the feed flow of HCl in G0 gives a HCl conversion of about 61.5%.
Cited Literature
[0201] WO2007/134771 A1 [0202] WO2011/111351 A1 [0203] WO2013/004651 A1 [0204] WO 2013/060628 A1 [0205] U.S. Pat. No. 2,418,930 A [0206] US 2004/052718
