Process for the preparation of phosgene

Abstract

The present invention relates to a continuous process for the preparation of phosgene, as well as to a preparation unit for carrying out the process.

Description

Technical Field

[0001] This invention relates to a continuous method for preparing phosgene and a production unit for carrying out the method. Technical Background

[0002] Phosgene is an industrially widely used reagent in carbonylation reactions, specifically in the preparation of acyl chlorides and isocyanates. Phosgene is primarily produced by the gas-phase catalysis of carbon monoxide and chlorine, typically over an activated carbon catalyst. Due to the exothermic reaction, the synthesis takes place in a cooled reactor, preferably a tubular reactor, where the catalyst is packed into reaction tubes and cooling in the jacket space is achieved by a liquid or boiling coolant medium.

[0003] Phosgene is prepared on a large scale by the catalytic gas-phase reaction of carbon monoxide and chlorine in the presence of a catalyst (e.g., activated carbon catalyst) according to the following reaction formula.

[0004]

[0005] The reaction is highly exothermic, with an enthalpy ΔH of -107.6 kJ / mol. To remove the heat of reaction, the reaction is typically carried out in a tubular reactor in which the catalyst is packed in tubes (see Ullmann's Encyclopedia of Industrial Chemistry, "Phosgene," 5th edition, Vol. A19, p. 413 and below, VCH Verlagsgesellschaft mbH, Weinheim, 1991). Generally, granular catalysts with a particle size of 3 to 5 mm are used in tubes with typical inner diameters of 35 to 70 mm, and typically 39 to 45 mm. In this reaction, excess carbon monoxide is often used to ensure complete conversion of chlorine and to produce phosgene that is predominantly chlorine-free, as chlorine can cause undesirable side reactions when phosgene is subsequently used. The reaction can be carried out without pressure, but is typically carried out under overpressures of 200–600 kPa (2–6 bar). Within this pressure range, the phosgene formed can be condensed after the reactor, where cooling water or other heat transfer fluids (such as organic heat transfer fluids) can be used, thus allowing the condenser to operate more economically.

[0006] Typically, the reaction begins at 40 to 50 °C, but the high reaction rate associated with its high exothermicity leads to the formation of hot spots well above 450 °C, often exceeding 500 °C, as mentioned by Christopher J. Mitchell et al. in "Selection of carbon catalysts for the industrial manufacture of phosgene," Hunterman Polyurethanes, Catal. Sci. Technol., 2012, 2109-2115. These localized high temperatures lead to catalyst deactivation / consumption, for example, by the chlorination of carbon to carbon tetrachloride along the length of the reaction tube in the presence of chlorine in the gas stream. At such high temperatures, chlorine has a strong effect on activated carbon catalysts. The higher the temperature, the higher the concentration of CCl4 formed, thus its carbon loss and stronger chlorination (stronger chemical bonds) are noteworthy. Moreover, removing the large amount of heat of reaction requires a corresponding number of individual tubes in the reactor. Furthermore, the high heat load in the chlorine-containing atmosphere causes corrosion and erosion of the tube wall material. This requires more inert and therefore more expensive pipe wall materials, as well as enhanced heat transfer in terms of coolant.

[0007] In summary, deactivation necessitates periodic catalyst replacement and consequently, shutdown of the production facility. The reactor investment is substantial due to the number of tubes and the use of higher-quality materials. Therefore, thermal management within the reactor is one of the major challenges that must be addressed to implement a safe and economical method in phosgene production. Summary of the Invention

[0008] Therefore, the object of the present invention is to provide an improved method for preparing phosgene. In particular, it is necessary to provide a new method for preparing phosgene that achieves high productivity, especially by increasing catalyst lifetime and efficiency. Surprisingly, it has been found that, according to the present invention, the method for preparing phosgene has high productivity and reduces the need to shut down production equipment to replace the catalyst.

[0009] Therefore, the present invention relates to a continuous method for preparing phosgene, comprising:

[0010] (i) Provide an airflow G1 containing carbon monoxide (CO) and chlorine (Cl2);

[0011] (ii) A gas flow G1 is introduced into a reaction zone Z1, and the gas flow G1 is brought into contact with a catalyst C1 contained in the reaction zone Z1 to obtain a gas flow GP containing phosgene, and one or more of carbon monoxide and chlorine, and the gas flow GP is removed from the reaction zone Z1.

[0012] (iii) Split the airflow GP to obtain at least two airflows including airflow G2 and airflow GR, wherein G2 and GR have the same chemical composition as GP, and the ratio of the mass flow rate f(GR) of airflow GR to the mass flow rate f(G2) of airflow G2, f(GR):f(G2), is in the range of 0.1:1 to 20:1.

[0013] During the standard operating mode of the continuous method, the airflow G1 provided according to (i) includes:

[0014] G1 is prepared as a mixture comprising at least two gas streams, the at least two gas streams comprising gas stream GR and j gas streams G0(k), where k = 1, ... j, wherein the j gas streams G0(k) generally comprise carbon monoxide (CO) and chlorine (Cl2) and wherein j is in the range of 1 to 3.

[0015] Preferably, j is 1 or 2, and more preferably 2.

[0016] Preferably, the mixture consists of at least two airflows as defined above. Detailed Implementation

[0017] For the f(GR):f(G2) ratio, it is preferably in the range of 0.2:1 to 10:1, more preferably in the range of 0.25:1 to 4:1, and even more preferably in the range of 0.3:1 to 3:1. More preferably, f(GR):f(G2) is in the range of 0.3:1 to 1.5:1. The ratio may also preferably be in the range of 0.5:1 to 1.5:1. Alternatively, preferably, f(GR):f(G2) is in the range of 5:1 to 8:1.

[0018] When using an adiabatic reactor, the preferred ratio of f(GR):f(G2) is in the range of 5:1 to 8:1. When using a cooling reactor, the preferred ratio of f(GR):f(G2) is in the range of 0.3:1 to 1.5:1.

[0019] Preferably, in the j-type gas flow G0(k), the molar ratio of chlorine to carbon monoxide is generally in the range of 0.6:1 to 0.999:1, more preferably in the range of 0.7:1 to 0.98, and even more preferably in the range of 0.85:1 to 0.95:1.

[0020] During the standard operating mode of the continuous method, it is preferable to provide airflow G1 according to (i) including:

[0021] G1 is prepared as a mixture comprising three gas streams, more preferably a mixture of these three gas streams, the three gas streams being gas stream GR and two gas streams G0(1) and G0(2), wherein the two gas streams G0(1) and G0(2) generally comprise carbon monoxide (CO) and chlorine (Cl2).

[0022] During the standard operating mode of the continuous method, it is preferable to provide airflow G1 according to (i) including:

[0023] According to (i), G1 is prepared as a mixture comprising three gas streams GR, G0(1), and G0(2), more preferably a mixture of these three gas streams, wherein G0(1) comprises carbon monoxide (CO) and G0(2) comprises chlorine (Cl2), which includes

[0024] - Combining airflow G0(1) with airflow G0(2), more preferably in a static mixer, and

[0025] - Mix the airflow GR with the combined airflows G0(1) and G0(2).

[0026] Preferably, according to (i), the mixing of the airflow GR with the two combined airflows G0(1) and G0(2) is carried out in a mixing device, wherein the mixing device is an injector, a static mixer or a dynamic mixer, more preferably an injector, wherein the injector is more preferably driven by the combined airflows G0(1) and G0(2).

[0027] Preferably, the combined airflows G0(1) and G0(2) have a pressure P0 and the airflow GR has a pressure PR, where P0>PR, and more preferably the airflow G1 has a pressure P1 and P0>P1>PR. Preferably, the pressure P0 is in the range of 2 to 20 bar (absolute), more preferably 4 to 10 bar (absolute).

[0028] Preferably, in the combined gas streams G0(1) and G0(2), the molar ratio of chlorine to carbon monoxide is in the range of 0.6:1 to 0.999:1, more preferably in the range of 0.7:1 to 0.98, and even more preferably in the range of 0.85:1 to 0.95:1.

[0029] In the context of this invention, it is preferred that the recirculation ratio is the ratio of the mass flow rate f(GR) of the gas stream GR to the mass flow rate f(GP) of the gas stream GP, f(GR):f(GP), ranging from 0.2:1 to 0.95:1. More preferably, the recirculation ratio is the ratio of the mass flow rate f(GR) of the gas stream GR to the mass flow rate f(GP) of the gas stream GP, f(GR):f(GP), ranging from 0.25:1 to 0.8:1, more preferably from 0.3:1 to 0.7:1, and even more preferably from 0.35:1 to 0.6:1. Or more preferably, the recirculation ratio is the ratio of the mass flow rate f(GR) of the gas stream GR to the mass flow rate f(GP) of the gas stream GP, f(GR):f(GP), ranging from 0.50:1 to 0.92:1, and even more preferably from 0.70:1 to 0.90:1. The latter ratio is particularly preferred when the reaction zone Z1 preferably comprises a non-cooled reactor as defined below.

[0030] The temperature T(G1) of the preferred airflow G1 is in the range of 20°C to 200°C, more preferably in the range of 50°C to 90°C, and even more preferably in the range of 70°C to 80°C.

[0031] Preferably, the temperature T(G0(k)) of the airflow G0(k) is in the range of 25°C to 60°C, more preferably in the range of 30°C to 40°C.

[0032] More preferably, the temperature T(G0(1)) of the airflow G0(1) is in the range of 25 to 60°C, more preferably in the range of 30 to 40°C, and the temperature T(G0(2)) of the airflow G0(2) is in the range of 25 to 60°C, more preferably in the range of 30 to 40°C.

[0033] During the standard operating mode of the continuous method, it is preferable to provide airflow G1 according to (i) including:

[0034] According to (i), G1 is prepared as a mixture comprising three gas streams GR, G0(1), and G0(2), more preferably a mixture of these three gas streams, wherein G0(1) comprises carbon monoxide (CO) and G0(2) comprises chlorine (Cl2), which includes

[0035] - Mix airflow G0(1) with airflow GR, and

[0036] - The airflow G0(2) is combined with the mixed airflow G0(1) and GR, preferably in a static mixer.

[0037] Preferably, according to (i), the mixing of airflow G0(1) and airflow GR is carried out in a mixing device, wherein the mixing device is an injector, a static mixer or a dynamic mixer, more preferably an injector, wherein the injector is more preferably driven by airflow G0(1).

[0038] Preferably, the airflow G0(1) has a pressure P0(1) and the airflow GR has a pressure PR, wherein P0(1) > PR. Preferably, the pressure P0 is in the range of 2 to 20 bar (absolute), more preferably 4 to 10 bar (absolute).

[0039] During the standard operating mode of the continuous method, it is preferable to provide airflow G1 according to (i) including

[0040] According to (i), G1 is prepared as a mixture comprising three gas streams GR, G0(1), and G0(2), more preferably a mixture of these three gas streams, wherein G0(1) comprises CO and G0(2) comprises chlorine (Cl2), which includes

[0041] - Mix airflow G0(2) with airflow GR, and

[0042] - The airflow G0(1) is combined with the mixed airflow G0(2) and GR, preferably in a static mixer.

[0043] Preferably, according to (i), the mixing of airflow G0(2) and airflow GR is carried out in a mixing device, wherein the mixing device is an injector, a static mixer or a dynamic mixer, more preferably an injector, wherein the injector is more preferably driven by airflow G0(2).

[0044] The preferred airflow G0(2) has a pressure P0(2) and the airflow GR has a pressure PR, wherein P0(2)>PR. More preferably, the pressure P0 is in the range of 2 to 20 bar (absolute), and more preferably 4 to 10 bar (absolute).

[0045] Preferably, 99 to 100% by weight, more preferably 99.5 to 100% by weight, and even more preferably 99.9 to 100% by weight, of the gas flow G0(1) is composed of carbon monoxide. In other words, preferably, the gas flow G0(1) is composed essentially of carbon monoxide, and more preferably of carbon monoxide.

[0046] Preferably, 99 to 100% by weight, more preferably 99.5 to 100% by weight, and even more preferably 99.9 to 100% by weight of the gas stream G0(2) is composed of chlorine. In other words, preferably, the gas stream G0(2) is substantially composed of chlorine, and more preferably, composed of chlorine.

[0047] In the context of this invention, the preferred reaction zone Z1 comprises a reactor containing catalyst C1.

[0048] Preferably, the reactor is a tubular reactor comprising one or more tubes, wherein the catalyst C1 is filled in the one or more tubes.

[0049] Preferably, the gas flow in the reactor is at most 450°C, more preferably at most 400°C, and even more preferably at most 350°C, the temperature of which is more preferably measured using multi-point thermocouples. More preferably, the temperature is controlled, for example, by fixing the recirculation ratio defined above and / or by changing the temperature of the gas flow G1. In practice, preferably, the amount and temperature of the recirculated gas (i.e., the gas flow GR) are selected to control the temperature of the reaction zone and the outlet temperature of the reaction zone.

[0050] The preferred reactor is a cooling reactor, and more preferably a cooling tube bundle reactor.

[0051] Preferably, the cooling reactor contains a coolant medium.

[0052] Preferably, the temperature of the coolant medium is more preferably in the range of 50 to 300°C, more preferably in the range of 50 to 270°C, more preferably in the range of 60 to 100°C, and more preferably in the range of 70 to 90°C.

[0053] Preferably, the coolant medium is selected from monochlorobenzene and water, more preferably monochlorobenzene.

[0054] Preferably, the cooling reactor includes one or more cooling zones, more preferably one or two cooling zones. When the cooling reactor includes one cooling zone, the temperature of the coolant medium is preferably 50 to 270°C, more preferably 60 to 100°C, and even more preferably 70 to 90°C.

[0055] When the cooling reactor preferably includes a cooling zone, the cooling zone preferably includes an inlet device for introducing coolant medium into the cooling pipes and an outlet device for recovering the coolant medium. This configuration is as follows: Figure 2a , 2b As shown in Figures 3 and 5.

[0056] When the cooling reactor preferably comprises two cooling zones (a first cooling zone and a second cooling zone), the first cooling zone preferably includes a first inlet device for introducing a first coolant medium into the cooling pipes and a first outlet device for recovering the first coolant medium; and the second cooling zone includes a second inlet device for introducing a second coolant medium into the cooling pipes and a second outlet device for recovering the second coolant medium. This configuration is as follows: Figure 6As shown. More preferably, the first coolant medium and the second coolant medium are the same coolant medium. It is now believed that this configuration with two zones allows for savings in the heat generated in the reaction zone Z1 used to produce high-value steam. The first cooling zone can operate, for example, in a temperature range of 200 to 300°C, preferably at a temperature of about 250°C. Preferably, as the heat transfer oil flows through the first cooling zone, the heat generated by the reaction of catalyst C1 in the reactor of reaction zone Z1 can be removed from the reactor of reaction zone Z1. Therefore, the oil recovered from the first cooling zone can be used to heat the solvent in another heat exchanger (outside the preparation unit for phosgene preparation). The second cooling zone can operate under normal conditions, i.e., at about 80°C. Reactors with more than one cooling zone can be as described in WO 03 / 072237A1.

[0057] When using a cooling reactor, preferably, the recirculation ratio is the ratio of the mass flow rate f(GR) of the gas stream GR to the mass flow rate f(GP) of the gas stream GP, f(GR):f(GP), which is in the range of 0.2:1 to 0.95:1. More preferably, the recirculation ratio is the ratio of the mass flow rate f(GR) of the gas stream GR to the mass flow rate f(GP) of the gas stream GP, f(GR):f(GP), which is in the range of 0.25:1 to 0.8:1.

[0058] Alternatively, the reactor is preferably a non-cooled reactor, and more preferably an adiabatic fixed-bed reactor.

[0059] When using an adiabatic reactor, preferably, the recirculation ratio is the ratio of the mass flow rate f(GR) of the gas stream GR to the mass flow rate f(GP) of the gas stream GP, f(GR):f(GP), which is in the range of 0.50:1 to 0.92:1, more preferably in the range of 0.70:1 to 0.90:1.

[0060] When using an adiabatic reactor, it is preferable that, during the standard operating mode of the continuous method, before preparing G1 into a mixture comprising at least two streams, more preferably at least two streams, according to (i), the method further includes a cooling gas stream GR, more preferably using a heat exchanger.

[0061] When using an adiabatic reactor, preferably, (ii) it further includes conveying the gas flow GP into a cooling device included in the reaction zone Z1 and then removing it from the reaction zone Z1, wherein the cooling device is more preferably one or more cooling pipes.

[0062] In the context of the present invention, preferably, the method further includes, after (iii), passing the airflow GR through the return device R, and then, during the standard operating mode of the continuous method, according to (i), preparing G1 in the injector as a mixture comprising at least two streams, preferably consisting of at least two streams.

[0063] Preferably, the return device R forms a loop outside the reactor for recirculating GR and, during the standard operating mode of the continuous method, mixes it with GO(k) according to (i). It is also conceivable that the return device R is preferably located inside the reactor, such as... Figure 4 As shown.

[0064] There are no particular limitations on catalyst C1, as long as the catalyst allows for the production of phosgene, preferably a carbon catalyst or a carbon-based catalyst—these two terms are interchangeable. Any catalyst known in the art for the preparation of phosgene can be used as catalyst C1, such as commercially available activated carbon from companies like Donau Carbon (Desorex, Supersorbon), Cabot (e.g., Norit RB4C), and Chemviron.

[0065] The preferred catalyst C1 is activated carbon from Donau Carbon.

[0066] Alternatively, preferably, catalyst C1 comprises, and preferably is, a porous material comprising carbon, micropores, and mesopores, wherein the micropores have a pore size of less than 2 nm, and wherein the mesopores have a pore size in the range of 2 nm to 50 nm.

[0067] The volume of the mesopores in the porous material is at least 0.45 ml / g. More preferably, the micropore volume is determined according to DIN 66135-2, the mesopore volume is determined according to DIN 66134, and the volume of the mesopores in the porous material is determined according to the Nonlocal Density Functional Theoretical (NLDFT) Advanced Pore Size Distribution (PSD) technique.

[0068] Preferably, the ratio of the volume of the mesopores to the volume of the micropores in the porous material is at least 1:1, more preferably in the range of 1.1:1 to 6:1, more preferably in the range of 1.15:1 to 5:1, and even more preferably in the range of 1.2:1 to 4:1. Preferably, the volumes of the mesopores and micropores in the porous material are determined using the dual isothermal NLDFT advanced PSD technique.

[0069] Preferably, the ratio of the volume of the mesopores to the total pore volume of the porous material is at least 0.5:1, more preferably in the range of 0.5:1 to 0.9:1, more preferably in the range of 0.55:1 to 0.85:1, more preferably in the range of 0.6:1 to 0.8:1, and even more preferably in the range of 0.65:1 to 0.8:1. Preferably, the volume of the mesopores and the total pore volume of the porous material are determined using the dual isothermal NLDFT advanced PSD technique.

[0070] Preferably, the volume of the mesopores in the porous material is at least 0.5 ml / g.

[0071] The total pore volume of the porous material is preferably in the range of 0.5 to 2.25 ml / g, more preferably in the range of 0.55 to 1.75 ml / g, and even more preferably in the range of 0.65 to 1.70 ml / g. Preferably, the total pore volume of the porous material is determined according to the dual isotherm NLDFT advanced PSD technique.

[0072] Preferably, the total pore volume of the porous material is less than or equal to 40%, more preferably less than or equal to 30%, more preferably less than or equal to 25%, more preferably less than or equal to 20%, more preferably less than or equal to 15%, more preferably less than or equal to 10%, more preferably less than or equal to 5%, more preferably less than or equal to 2.5%, more preferably less than or equal to 1%, which is a mesopore with a pore size greater than 20 nm.

[0073] Preferably, the mesopore volume of the porous material is in the range of 0.50 to 0.54 ml / g, more preferably in the range of 0.51 to 0.53 ml / g, and the ratio of the mesopore volume to the total pore volume of the porous material is in the range of 0.70:1 to 0.75:1, more preferably in the range of 0.72:1 to 0.74:1. Preferably, the mesopore volume and the total pore volume of the porous material are determined according to the dual isothermal NLDFT advanced PSD technique.

[0074] Alternatively, preferably, the mesopore volume of the porous material is in the range of 0.64 to 0.70 ml / g, more preferably in the range of 0.65 to 0.67 ml / g, and the ratio of the mesopore volume to the total pore volume of the porous material is in the range of 0.72:1 to 0.78:1, more preferably in the range of 0.73:1 to 0.76:1. Preferably, the mesopore volume and the total pore volume of the porous material are determined using the dual isothermal NLDFT advanced PSD technique.

[0075] Preferably, the volume of the micropores in the porous material—more preferably measured according to the dual isotherm NLDFT advanced PSD technique—is at most 0.7 ml / g, and more preferably at most 0.6 ml / g.

[0076] For porous materials, the BET specific surface area is preferably at least 500 m². 2 / g, more preferably 500 to 2500m 2 Within the range of / g, more preferably within 550 to 1800m 2 Within the range of / g, more preferably within 600 to 1500m 2 Within the range of / g.

[0077] Preferably, the total specific surface area of ​​the porous material, as measured by the dual isotherm NLDFT advanced PSD technique, is at least 600 m². 2 / g, more preferably 650 to 2000m 2 Within the range of / g, more preferably within 700 to 1800m 2 Within the range of / g.

[0078] Preferably, the specific surface area of ​​the porous material caused by mesopores, as measured by the dual isotherm NLDFT advanced PSD technique, is between 70 and 250 m². 2 Within the range of / g, more preferably 80 to 170m 2 Within the range of / g.

[0079] Preferably, the ratio of the specific surface area of ​​the porous material caused by the mesopores to the total specific surface area of ​​the porous material is in the range of 0.07:1 to 0.40:1, more preferably in the range of 0.07:1 to 0.20:1.

[0080] Preferably, the porous material is pyrolytic carbon aerogel.

[0081] Preferably, the porous material is an active pyrolytic carbon aerogel.

[0082] Preferably, 99 to 100% by weight, more preferably 99.5 to 100% by weight, and even more preferably 99.9 to 100% by weight, of the porous material is composed of carbon.

[0083] Preferably, the porous material comprises less than or equal to 0.5% by weight of oxygen.

[0084] Preferably, the porous material comprises less than or equal to 0.5% by weight, more preferably less than or equal to 0.1% by weight, of hydrogen.

[0085] Preferably, the porous material is composed of nitrogen in a weight percentage of less than or equal to 0.01%.

[0086] Preferably, the ash content of the porous material is less than or equal to 0.1 wt%, more preferably less than or equal to 0.08 wt%, more preferably less than or equal to 0.05 wt%, more preferably less than or equal to 0.03 wt%, more preferably less than or equal to 0.025 wt%, more preferably less than or equal to 0.01 wt%, more preferably less than or equal to 0.0075 wt%, more preferably less than or equal to 0.005 wt%, more preferably less than or equal to 0.001 wt%, based on the weight of the porous material, as calculated from total internal reflection X-ray fluorescence data.

[0087] Preferably, the total content of impurities of elements with atomic numbers ranging from 11 to 92 in the porous material is less than 500 ppm, more preferably less than 300 ppm, more preferably less than 200 ppm, and more preferably less than 100 ppm, as measured by total internal reflection X-ray fluorescence (TXRF).

[0088] Preferably, 50 to 98% by weight, more preferably 60 to 95% by weight, of the gas flow GP is composed of phosgene.

[0089] Preferably, according to (iii), the airflow GP is split to obtain two airflows: airflow G2 and airflow GR.

[0090] Preferably, the method further includes

[0091] (iv) The feed stream G2 is conveyed into the reaction zone Z2, so that the gas stream G2 comes into contact with the catalyst C2 contained in the reaction zone Z2, thereby obtaining a gas stream GF containing phosgene, and the gas stream GF is removed from the reaction zone Z2.

[0092] Preferably, the reaction zone Z2 includes a reactor containing catalyst C2, more preferably a tubular reactor including one or more tubes, wherein catalyst C2 is filled in the one or more tubes.

[0093] Preferably, the reactor is a cooled reactor, and more preferably a cooled tube bundle reactor. Alternatively, the reactor is preferably an adiabatic fixed-bed reactor.

[0094] Preferably, the cooling reactor comprises a coolant medium, more preferably having a temperature range of 50 to 270°C, more preferably 60 to 100°C, and even more preferably 70 to 90°C. Preferably, the coolant medium is selected from monochlorobenzene and water, more preferably monochlorobenzene.

[0095] There are no particular limitations on catalyst C2, as long as it allows for the production of phosgene. Any catalyst known in the art for the preparation of phosgene can be used as catalyst C2 in this invention. Preferably, it contains carbon. Preferably, catalyst C2 has the same chemical and physical composition as catalyst C1. Alternatively, preferably, catalyst C2 has a different chemical and / or physical composition than catalyst C1. More preferably, catalyst C2 has the same chemical and physical composition as catalyst C1.

[0096] Preferably, the concentration of phosgene in the airflow GF is higher than the concentration of phosgene in the airflow GP.

[0097] The gas stream GF preferably consists of chlorine gas at a maximum of 500 ppm by weight, more preferably 0 to 300 ppm by weight, and even more preferably 0 to 100 ppm by weight.

[0098] Preferably, the method further includes

[0099] (v) The phosgene of the gas stream GF obtained in (iv) is condensed. In the context of this invention, multi-step condensation is also preferred in the method of this invention, more preferably accompanied by adsorption or distillation steps.

[0100] Preferably, CO recycling is not performed after (iv) or (v). However, it is also conceivable to perform CO recycling.

[0101] The present invention also relates to a preparation unit for carrying out the method of the present invention, the unit comprising:

[0102] -Reaction zone Z1, including

[0103] - An inlet device for conveying airflow G1 into Z1;

[0104] -Catalyst C1;

[0105] - A reaction apparatus for bringing gas stream G1 into contact with the catalyst C1;

[0106] - An outlet device for removing airflow GP from Z1;

[0107] - Material flow splitting device S, used to split airflow GP into at least two material flows, preferably two material flows including airflow GR and airflow G2;

[0108] - A means for conveying airflow GP into the device S;

[0109] - At least one, preferably two, devices M for preparing G1 into a mixture comprising at least two material streams;

[0110] - Return device R, used to transfer the airflow GR from S into the device M for preparing G1.

[0111] The preferred mixture consists of at least two material streams.

[0112] The preferred reaction device for reaction zone Z1 is a reactor.

[0113] The reactor in the preferred reaction zone Z1 is a tubular reactor containing one or more tubes, and more preferably a tube bundle reactor.

[0114] Preferably, the tubular reactor comprises one or more tubes and the catalyst C1 is contained in the one or more tubes.

[0115] Preferably, the tubular reactor comprises 1 to 10,000 tubes, more preferably 1,000 to 9,000 tubes.

[0116] Preferably, the length of the tubular reactor tube is in the range of 1.5 to 12 m, more preferably in the range of 1.8 to 10 m, and even more preferably in the range of 1.9 to 5 m.

[0117] The tubular reactor preferably has one or more tubes, more preferably the tubes of the tubular reactor, with an inner diameter in the range of 20 to 90 mm, more preferably in the range of 30 to 60 mm, and even more preferably in the range of 35 to 50 mm.

[0118] The tubular reactor preferably has one or more tubes, more preferably the tubes of the tubular reactor, with a wall thickness in the range of 2.0 to 4.0 mm, preferably in the range of 2.5 to 3.0 mm.

[0119] Preferably, one or more tubes of the tubular reactor, more preferably the tubes of the tubular reactor, are made of corrosion-resistant material, preferably iron-based alloy, nickel-based alloy or nickel, more preferably duplex steel 1.4462, stainless steel 1.4571 or stainless steel 1.4541.

[0120] Preferably, the reaction apparatus in reaction zone Z1 is cooled, more preferably by cooling with one or more of water and monochlorobenzene, and even more preferably by cooling with monochlorobenzene.

[0121] The preferred reaction apparatus for reaction zone Z1 is a cooled tube bundle reactor. Preferably, the cooled reactor includes one or more cooling zones, more preferably one or two cooling zones.

[0122] The cooling reactor preferably includes one or more cooling zones, more preferably one or two cooling zones. When the cooling reactor includes one cooling zone, the temperature of the coolant medium is preferably in the range of 50 to 270°C, more preferably in the range of 60 to 100°C, and even more preferably in the range of 70 to 90°C.

[0123] When the cooling reactor preferably includes a cooling zone, the cooling zone preferably includes an inlet device for introducing coolant medium into the cooling pipes and an outlet device for recovering the coolant medium. This configuration is as follows: Figure 2a , 2b As shown in Figures 3 and 5.

[0124] When the cooling reactor preferably comprises two cooling zones (a first cooling zone and a second cooling zone), preferably, the first cooling zone includes a first inlet device for introducing a first coolant medium into the cooling pipes and a first outlet device for recovering the first coolant medium; and the second cooling zone includes a second inlet device for introducing a second coolant medium into the cooling pipes and a second outlet device for recovering the second coolant medium. This configuration is as follows... Figure 6 As shown. More preferably, the first coolant medium and the second coolant medium are the same coolant medium. It is now believed that this configuration with two zones allows for savings in the heat generated in the reaction zone Z1 used to produce high-value steam. The first cooling zone can operate, for example, in a temperature range of 200 to 300°C, preferably at about 250°C. Preferably, as the heat transfer oil flows through the first cooling zone, the heat generated by the reaction of catalyst C1 in the reactor of reaction zone Z1 can be discharged from the reactor of reaction zone Z1. Therefore, the oil recovered from the first cooling zone can be used to heat the solvent in another heat exchanger (outside the preparation unit for phosgene preparation). The second cooling zone can operate under normal conditions, i.e., at about 80°C. Reactors with more than one cooling zone can be as described in WO 03 / 072237A1.

[0125] Alternatively, preferably, the reaction apparatus of reaction zone Z1 is a non-cooled reaction apparatus, and reaction zone Z1 also includes a cooling device located downstream of the reaction apparatus.

[0126] Preferably, when the reaction device in reaction zone Z1 is a non-cooled reaction device, the return device R further includes a cooling device.

[0127] Preferably, the non-cooled reaction device is an adiabatic fixed-bed reactor.

[0128] In the context of this invention, the return device R is preferably a return pipe, more preferably an external return pipe of the Z1 reactor or an internal return pipe of the Z1 reactor, and even more preferably an external return pipe.

[0129] In this regard, it should be noted that the inner diameter of the return pipe is usually determined according to the capacity. Preferably, the inner diameter of the return pipe is in the range of 100 to 500 mm, more preferably in the range of 150 to 300 mm.

[0130] Preferably, the return pipe is made of a corrosion-resistant material, more preferably of an iron-based alloy, a nickel-based alloy, or nickel, and even more preferably of duplex steel 1.4462, stainless steel 1.4571, or stainless steel 1.4541.

[0131] Preferably, the unit includes two devices M for preparing G1 into a mixture comprising at least two streams, more preferably at least two streams. Device M(e) is preferably an injector for mixing GR and gas flow G0(k), and device M(s) is preferably a static mixer.

[0132] Preferably, device M(s) is located upstream of device M(e), device M(s) is a static mixer for merging G0(1) and G0(2), and device M(e) is an injector for mixing GR with the merged airflows G0(1) and G0(2).

[0133] Preferably, as an alternative, device M(e) is located upstream of device M(s), device M(e) is an injector for mixing GR with G0(1) or G0(2), and device M(s) is a static mixer for merging another of G0(1) and G0(2) with the mixed airflow G0(1) or G0(2).

[0134] Preferably, the preparation unit further includes:

[0135] -Reaction zone Z2, including

[0136] - An inlet device for conveying airflow G2 into Z2;

[0137] -Catalyst C2;

[0138] - A reaction apparatus for bringing gas stream G1 into contact with the catalyst C2;

[0139] - An outlet device for removing airflow GF from Z2;

[0140] The preferred reaction device for reaction zone Z2 is a reactor.

[0141] The reactor in the preferred reaction zone Z2 is a tubular reactor comprising one or more tubes, more preferably a bundled tube reactor. The reactor used in this invention can be any cooling reactor known to those skilled in the art, for example, a reactor as described in WO 03 / 072237A1.

[0142] Preferably, the tubular reactor comprises one or more tubes and the catalyst C2 is contained in one or more tubes.

[0143] Preferably, the tubular reactor comprises 1 to 10,000 tubes, more preferably 1,000 to 9,000 tubes.

[0144] Preferably, one or more tubes of the tubular reactor, more preferably the tubes of the tubular reactor, have a length in the range of 1.5 to 12 m, more preferably in the range of 1.8 to 10 m, and even more preferably in the range of 1.9 to 5 m.

[0145] Preferably, one or more tubes of the tubular reactor, more preferably the tubes of the tubular reactor, have an inner diameter in the range of 20 to 90 mm, more preferably in the range of 30 to 60 mm, and even more preferably in the range of 35 to 50 mm.

[0146] Preferably, one or more tubes of the tubular reactor, more preferably the tubes of the tubular reactor, have a wall thickness in the range of 2.0 to 4.0 mm, more preferably in the range of 2.5 to 3.0 mm.

[0147] Preferably, one or more tubes of the tubular reactor, more preferably the tubes of the tubular reactor, are made of corrosion-resistant material, more preferably of iron-based alloy, nickel-based alloy or nickel, and even more preferably of duplex steel 1.4462, stainless steel 1.4571 or stainless steel 1.4541.

[0148] Preferably, the reaction apparatus in reaction zone Z2 is cooled by a coolant medium, wherein the coolant medium is one or more of water and monochlorobenzene, more preferably monochlorobenzene.

[0149] Preferably, the reaction device in reaction zone Z2 is a cooled tube bundle reactor.

[0150] Preferably, as an alternative, the reaction apparatus for reaction zone Z2 is an adiabatic fixed-bed reactor.

[0151] In the context of this invention, it is preferable that the surface loading of phosgene obtained by the preparation unit is between 0.5 and 6 kg / m³. 2 Within the range of s, more preferably from 0.7 to 5 kg / m 2 More preferably, within the range of 0.7 to 4 kg / m 2 Within the range of s, more preferably from 0.8 to 3.5 kg / m 2 Within the range of s.

[0152] Preferably, the preparation unit further includes a device for condensing the phosgene in the gas stream GF.

[0153] The present invention also relates to the use of the preparation unit of the present invention for the continuous preparation of phosgene.

[0154] For completeness, in the context of this invention, it should be noted that since gas streams GR, G2 and GP have the same chemical composition, the use of a condenser in the reaction zone, preferably downstream of the reactor, is excluded, thereby excluding the flow of gas stream GR through the condenser before the preparation of G1 and the flow of gas stream GP through the condenser before the split according to (iii).

[0155] The invention is further illustrated by the following group of embodiments and combinations of embodiments derived from the shown dependencies and reverse references. In particular, it should be noted that in each instance referring to the scope of the embodiments, such as in the context of a term like “the method described in any one of embodiments 1 to 4,” each embodiment within that scope is intended to explicitly disclose to a person skilled in the art that the wording of that term should be understood by a person skilled in the art to be synonymous with “the method described in any one of embodiments 1, 2, 3, and 4.” Furthermore, it should be explicitly noted that the following group of embodiments represents appropriate structural portions of a general description of preferred aspects of the invention, thereby appropriately supporting the invention, but not representing the claims of the invention.

[0156] 1. A continuous method for preparing phosgene, comprising:

[0157] (i) Provide an airflow G1 containing carbon monoxide (CO) and chlorine (Cl2);

[0158] (ii) A gas flow G1 is introduced into a reaction zone Z1, and the gas flow G1 is brought into contact with a catalyst C1 contained in the reaction zone Z1 to obtain a gas flow GP containing phosgene, and one or more of carbon monoxide and chlorine, and the gas flow GP is removed from the reaction zone Z1.

[0159] (iii) Split the airflow GP to obtain at least two airflows including airflow G2 and airflow GR, wherein G2 and GR have the same chemical composition as GP, and the ratio of the mass flow rate f(GR) of airflow GR to the mass flow rate f(G2) of airflow G2, f(GR):f(G2), is in the range of 0.1:1 to 20:1.

[0160] During the standard operating mode of the continuous method, the airflow G1 provided according to (i) includes:

[0161] G1 is prepared as a mixture comprising at least two gas streams, the at least two gas streams comprising gas stream GR and j gas streams G0(k), where k = 1, ... j, wherein the j gas streams G0(k) generally comprise carbon monoxide (CO) and chlorine (Cl2) and wherein j is in the range of 1 to 3.

[0162] 2. The method according to implementation scheme 1, wherein j is 1 or 2, preferably 2.

[0163] 3. The method according to embodiment 1 or 2, wherein the f(GR):f(G2) ratio is in the range of 0.2:1 to 10:1, preferably in the range of 0.25:1 to 4:1, more preferably in the range of 0.3:1 to 3:1, even more preferably in the range of 0.3:1 to 1.5:1, or preferably in the range of 5:1 to 8:1.

[0164] 4. The method according to any one of embodiments 1 to 3, wherein in the j-type gas flow G0(k), the molar ratio of the total amount of chlorine to the total amount of carbon monoxide is in the range of 0.6:1 to 0.999:1, preferably in the range of 0.7:1 to 0.98, and more preferably in the range of 0.85:1 to 0.95:1.

[0165] 5. The method according to any one of embodiments 1 to 4, wherein during the standard operating mode of the continuous method, providing airflow G1 according to (i) includes:

[0166] G1 is prepared as a mixture of three gas streams, preferably a mixture of these three gas streams, which are gas stream GR and two gas streams G0(1) and G0(2), wherein the two gas streams G0(1) and G0(2) generally contain carbon monoxide (CO) and chlorine (Cl2).

[0167] 6. The method according to any one of embodiments 1 to 5, wherein during the standard operating mode of the continuous method, providing airflow G1 according to (i) includes:

[0168] G1 is prepared as a mixture comprising three gas streams GR, G0(1), and G0(2), more preferably a mixture of these three gas streams, wherein G0(1) comprises carbon monoxide (CO) and G0(2) comprises chlorine gas (Cl2), which includes

[0169] - Combine airflow G0(1) with airflow G0(2), preferably in a static mixer, and

[0170] - Mix the airflow GR with the combined airflows G0(1) and G0(2).

[0171] 7. The method according to embodiment 6, wherein, according to (i), the mixing of the airflow GR with the two combined airflows G0(1) and G0(2) is carried out in a mixing device, wherein the mixing device is an injector, a static mixer or a dynamic mixer, preferably an injector, wherein the injector is more preferably driven by the combined airflows G0(1) and G0(2).

[0172] 8. The method according to embodiment 6 or 7, wherein the combined airflows G0(1) and G0(2) have pressure P0 and the airflow GR has pressure PR, wherein P0>PR, wherein preferably the airflow G1 has pressure P1 and P0>P1>PR; wherein more preferably the pressure P0 ranges from 2 to 20 bar (absolute), more preferably from 4 to 10 bar (absolute).

[0173] 9. The method according to any one of embodiments 6 to 8, wherein in the combined gas streams G0(1) and G0(2), the molar ratio of chlorine to carbon monoxide is in the range of 0.6:1 to 0.999:1, preferably in the range of 0.7:1 to 0.98, and more preferably in the range of 0.85:1 to 0.95:1.

[0174] 10. The method according to any one of embodiments 1 to 9, wherein the recirculation ratio is the ratio of the mass flow rate f(GR) of the airflow GR to the mass flow rate f(GP) of the airflow GP, f(GR):f(GP), which is in the range of 0.2:1 to 0.95:1, preferably in the range of 0.25:1 to 0.8:1, more preferably in the range of 0.3:1 to 0.7:1, and even more preferably in the range of 0.35:1 to 0.6:1.

[0175] 11. The method according to any one of embodiments 1 to 10, wherein the temperature T(G1) of the airflow G1 is in the range of 20°C to 200°C, preferably in the range of 50°C to 90°C, and more preferably in the range of 70°C to 80°C.

[0176] 12. The method according to any one of embodiments 1 to 11, wherein the temperature T(G0(k)) of the gas flow G0(k) is in the range of 25°C to 60°C, preferably in the range of 30°C to 40°C.

[0177] Preferably, in respect of embodiment 12 being subordinate to embodiment 6, the temperature T(G0(1)) of the airflow G0(1) is in the range of 25 to 60°C, more preferably in the range of 30 to 40°C, and the temperature T(G0(2)) of the airflow G0(2) is in the range of 25 to 60°C, more preferably in the range of 30 to 40°C.

[0178] 13. The method according to any one of embodiments 1 to 5, wherein during the standard operating mode of the continuous method, providing airflow G1 according to (i) includes:

[0179] G1 is prepared as a mixture comprising three gas streams GR, G0(1), and G0(2), more preferably a mixture of these three gas streams, wherein G0(1) comprises carbon monoxide (CO) and G0(2) comprises chlorine (Cl2), which includes

[0180] - Mix airflow G0(1) with airflow GR, and

[0181] - Combine the airflow G0(2) with the mixed airflow G0(1) and GR, preferably in a static mixer.

[0182] 14. The method according to embodiment 13, wherein, according to (i), the mixing of airflow G0(1) and airflow GR is carried out in a mixing device, wherein the mixing device is an injector, a static mixer or a dynamic mixer, more preferably an injector, wherein the injector is more preferably driven by airflow G0(1).

[0183] 15. The method according to embodiment 13 or 14, wherein the airflow G0(1) has pressure P0(1) and the airflow GR has pressure PR, wherein P0(1) > PR; wherein more preferably the pressure P0 is in the range of 2 to 20 bar (absolute), more preferably 4 to 10 bar (absolute).

[0184] 16. The method according to any one of embodiments 1 to 5, wherein during the standard operating mode of the continuous method, according to (i) providing airflow G1 includes

[0185] G1 is prepared as a mixture comprising three gas streams GR, G0(1), and G0(2), more preferably a mixture of these three gas streams, wherein G0(1) contains CO and G0(2) contains chlorine (Cl2), which includes

[0186] - Mix airflow G0(2) with airflow GR, and

[0187] - Combine airflow G0(1) with mixed airflow G0(2) and GR, preferably in a static mixer.

[0188] 17. The method according to embodiment 16, wherein, according to (i), the mixing of airflow G0(2) with airflow GR is carried out in a mixing device, wherein the mixing device is an injector, a static mixer or a dynamic mixer, preferably an injector, wherein the injector is more preferably driven by airflow G0(2).

[0189] 18. The method according to embodiment 16 or 17, wherein the airflow G0(2) has pressure P0(2) and the airflow GR has pressure PR, wherein P0(2)>PR; wherein more preferably the pressure P0 is in the range of 2 to 20 bar (absolute), preferably 4 to 10 bar (absolute).

[0190] 19. The method according to any one of embodiments 5 to 18, wherein 99 to 100% by weight, preferably 99.5 to 100% by weight, more preferably 99.9 to 100% by weight, of the gas stream G0(1) is composed of carbon monoxide.

[0191] 20. The method according to any one of embodiments 5 to 19, wherein 99 to 100% by weight, preferably 99.5 to 100% by weight, more preferably 99.9 to 100% by weight, of the gas stream G0(2) is composed of chlorine.

[0192] 21. The method according to any one of embodiments 1 to 20, wherein the reaction zone Z1 comprises a reactor containing catalyst C1.

[0193] 22. The method according to embodiment 21, wherein the reactor is a tubular reactor comprising one or more tubes, wherein the catalyst C1 is filled in the one or more tubes.

[0194] 23. The method according to embodiment 22, wherein the gas flow in the reactor is at most 450°C, preferably at most 400°C, more preferably at most 350°C, and the temperature is preferably measured using a multi-point thermocouple.

[0195] 24. The method according to embodiment 22 or 23, wherein the reactor is a cooling reactor, preferably a cooling tube bundle reactor.

[0196] 25. The method according to any one of embodiments 22 to 24, wherein the reactor comprises a coolant medium, the coolant medium preferably having a temperature range of 50 to 270°C, more preferably 60 to 100°C, and even more preferably 70 to 90°C, wherein the coolant medium is preferably selected from monochlorobenzene and water, more preferably monochlorobenzene.

[0197] 26. The method according to embodiment 21, wherein the reactor is a non-cooled reactor, preferably an adiabatic fixed-bed reactor.

[0198] 27. The method according to embodiment 26, wherein, prior to preparing G1 into a mixture comprising at least two streams, preferably consisting of at least two streams, during the standard operating mode of the continuous method, the method further includes a cooling gas stream GR, preferably using a heat exchanger.

[0199] 28. The method according to embodiment 26, wherein (ii) further comprises conveying the airflow GP to a cooling device included in the reaction zone Z1 and then removing it from the reaction zone Z1, wherein the cooling device is preferably one or more cooling pipes.

[0200] 29. The method according to any one of embodiments 1 to 28 further includes,

[0201] After (iii), the airflow GR is passed through the return device R, and then during the standard operating mode of the continuous method, according to (i), G1 is prepared in the injector as a mixture comprising at least two streams, preferably consisting of at least two streams.

[0202] 30. The method according to embodiment 29, wherein, as it pertains to any one of embodiments 22 to 28, the return device R forms a loop outside the reactor for recirculating GR and mixing it with G0(k) according to (i) during the standard operating mode of the continuous method.

[0203] 31. The method according to any one of embodiments 1 to 30, wherein the catalyst C1 comprises, preferably, a porous material comprising carbon, micropores and mesopores, wherein the micropores have a pore size of less than 2 nm, preferably determined according to DIN 66135-2; and wherein the mesopores have a pore size in the range of 2 nm to 50 nm, preferably determined according to DIN 66134;

[0204] The volume of the mesopores in the porous material is preferably determined using the double isotherm nonlocal density functional theory (NLDFT) advanced pore size distribution (PSD) technique, and is at least 0.45 ml / g.

[0205] 32. The method according to embodiment 31, wherein the ratio of the volume of the mesopores of the porous material to the volume of the micropores of the porous material is at least 1:1, more preferably in the range of 1.1:1 to 6:1, more preferably in the range of 1.15:1 to 5:1, and even more preferably in the range of 1.2:1 to 4:1. Preferably, the volume of the mesopores and the volume of the micropores of the porous material are determined according to the dual isothermal NLDFT advanced PSD technique.

[0206] 33. The method according to embodiment 31 or 32, wherein the ratio of the volume of the mesopores of the porous material to the total pore volume of the porous material is at least 0.5:1, preferably in the range of 0.5:1 to 0.9:1, more preferably in the range of 0.55:1 to 0.85:1, more preferably in the range of 0.6:1 to 0.8:1, and even more preferably in the range of 0.65:1 to 0.8:1; preferably, the volume of the mesopores and the total pore volume of the porous material are determined according to the dual isothermal NLDFT advanced PSD technique.

[0207] 34. The method according to any one of embodiments 31 to 33, wherein the volume of the mesopores in the porous material is at least 0.5 ml / g.

[0208] 35. The method according to any one of embodiments 31 to 34, wherein the total pore volume of the porous material is in the range of 0.5 to 2.25 ml / g, preferably in the range of 0.55 to 1.75 ml / g, more preferably in the range of 0.65 to 1.70 ml / g; preferably, the total pore volume of the porous material is determined according to the dual isotherm NLDFT advanced PSD technique.

[0209] 36. The method according to any one of embodiments 31 to 35, wherein the total pore volume of the porous material is less than or equal to 40%, preferably less than or equal to 30%, more preferably less than or equal to 25%, more preferably less than or equal to 20%, more preferably less than or equal to 15%, more preferably less than or equal to 10%, more preferably less than or equal to 5%, more preferably less than or equal to 2.5%, more preferably less than or equal to 1%, and is a mesopore with a pore size greater than 20 nm.

[0210] 37. The method according to any one of embodiments 31 to 36, wherein the volume of the mesopores of the porous material is in the range of 0.50 to 0.54 ml / g, preferably in the range of 0.51 to 0.53 ml / g, and the ratio of the volume of the mesopores of the porous material to the total pore volume of the porous material is in the range of 0.70:1 to 0.75:1, preferably in the range of 0.72:1 to 0.74:1; preferably, the volume of the mesopores and the total pore volume of the porous material are determined according to the dual isothermal NLDFT advanced PSD technique.

[0211] 38. The method according to any one of embodiments 31 to 36, wherein the volume of the mesopores of the porous material is in the range of 0.64 to 0.70 ml / g, preferably in the range of 0.65 to 0.67 ml / g, and the ratio of the volume of the mesopores of the porous material to the total pore volume of the porous material is in the range of 0.72:1 to 0.78:1, preferably in the range of 0.73:1 to 0.76:1; preferably, the volume of the mesopores and the total pore volume of the porous material are determined according to the dual isothermal NLDFT advanced PSD technique.

[0212] 39. The method according to any one of embodiments 31 to 38, wherein the volume of the micropores of the porous material is preferably determined by double isothermal NLDFT advanced PSD technology to be at most 0.7 ml / g, preferably at most 0.6 ml / g.

[0213] 40. The method according to any one of embodiments 31 to 39, wherein the BET specific surface area of ​​the porous material is at least 500 m². 2 / g, preferably between 500 and 2500m 2 Within the range of / g, more preferably within 550 to 1800m 2 Within the range of / g, more preferably within 600 to 1500m 2 Within the range of / g.

[0214] 41. The method according to any one of embodiments 31 to 40, wherein the total specific surface area of ​​the porous material is at least 600 m², as measured by dual isothermal NLDFT advanced PSD technology. 2 / g, preferably between 650 and 2000m 2Within the range of / g, more preferably within 700 to 1800m 2 Within the range of / g.

[0215] 42. The method according to any one of embodiments 31 to 41, wherein the specific surface area of ​​the porous material caused by the mesopores is between 70 and 250 m², as measured by dual isothermal NLDFT advanced PSD technology. 2 Within the range of / g, preferably between 80 and 170m 2 Within the range of / g.

[0216] 43. The method according to embodiment 42, wherein the ratio of the specific surface area of ​​the porous material caused by the mesopores to the total specific surface area of ​​the porous material is in the range of 0.07:1 to 0.40:1, preferably in the range of 0.07:1 to 0.20:1.

[0217] 44. The method according to any one of embodiments 31 to 43, wherein the porous material is pyrolytic carbon aerogel, preferably active pyrolytic carbon aerogel.

[0218] 45. The method according to any one of embodiments 31 to 44, wherein 99 to 100% by weight, more preferably 99.5 to 100% by weight, more preferably 99.9 to 100% by weight, of the porous material is composed of carbon.

[0219] 46. ​​The method according to any one of embodiments 31 to 45, wherein less than or equal to 0.5% by weight of the porous material is composed of oxygen.

[0220] 47. The method according to any one of embodiments 31 to 46, wherein less than or equal to 0.5% by weight, preferably less than or equal to 0.1% by weight, of the porous material is composed of hydrogen.

[0221] 48. The method according to any one of embodiments 1 to 17, wherein less than or equal to 0.01% by weight of the porous material is composed of nitrogen.

[0222] 49. The method according to any one of embodiments 1 to 18, wherein the ash content of the porous material is less than or equal to 0.1 wt%, preferably less than or equal to 0.08 wt%, more preferably less than or equal to 0.05 wt%, more preferably less than or equal to 0.03 wt%, more preferably less than or equal to 0.025 wt%, more preferably less than or equal to 0.01 wt%, more preferably less than or equal to 0.0075 wt%, more preferably less than or equal to 0.005 wt%, more preferably less than or equal to 0.001 wt%, calculated from total internal reflection X-ray fluorescence data based on the weight of the porous material.

[0223] 50. The method according to any one of embodiments 1 to 19, wherein the total content of impurities of elements with atomic numbers ranging from 11 to 92 in the porous material, as measured by total internal reflection X-ray fluorescence (TXRF), is less than 500 ppm, preferably less than 300 ppm, more preferably less than 200 ppm, and even more preferably less than 100 ppm.

[0224] 51. The method according to any one of embodiments 1 to 50, wherein 50 to 98% by weight, preferably 60 to 95% by weight, of the gas flow GP is composed of phosgene.

[0225] 52. The method according to any one of embodiments 1 to 51, wherein the airflow GP is split according to (iii) to obtain two airflows: airflow G2 and airflow GR.

[0226] 53. The method according to any one of embodiments 1 to 52 further includes

[0227] (iv) The feed stream G2 is conveyed into the reaction zone Z2, so that the gas stream G2 comes into contact with the catalyst C2 contained in the reaction zone Z2, thereby obtaining a gas stream GF containing phosgene, and the gas stream GF is removed from the reaction zone Z2.

[0228] 54. The method according to embodiment 53, wherein the reaction zone Z2 includes a reactor containing catalyst C2, preferably a tubular reactor comprising one or more tubes, wherein catalyst C2 is filled in the one or more tubes.

[0229] 55. The method according to embodiment 54, wherein the reactor is a cooled reactor, preferably a cooled tube bundle reactor; or the reactor is a non-cooled reactor, preferably an adiabatic fixed bed reactor.

[0230] 56. The method according to embodiment 55, wherein the cooling reactor comprises a coolant medium, the coolant medium preferably having a temperature in the range of 50 to 270°C, more preferably 60 to 100°C, more preferably 70 to 90°C; wherein preferably, the coolant medium is selected from monochlorobenzene and water, more preferably monochlorobenzene.

[0231] 57. The method according to any one of embodiments 53 to 56, wherein catalyst C2 comprises carbon, wherein preferably catalyst C2 has the same chemical and physical composition as catalyst C1, or preferably catalyst C2 has a different chemical and / or physical composition than catalyst C1, more preferably catalyst C2 has the same chemical and physical composition as catalyst C1.

[0232] 58. The method according to any one of embodiments 53 to 57, wherein the concentration of phosgene in the airflow GF is higher than the concentration of phosgene in the airflow GP.

[0233] 59. The method according to any one of embodiments 53 to 58, wherein the gas stream GF of up to 500 ppm by weight, preferably 0 to 300 ppm by weight, more preferably 0 to 100 ppm by weight, is composed of chlorine.

[0234] 60. The method according to any one of embodiments 1 to 59 further includes

[0235] (v) condense the phosgene of the gas flow GF obtained in (iv).

[0236] 61. In the method according to any one of embodiments 1 to 60, CO is not recycled after (iv) or (v).

[0237] 62. A preparation unit for implementing the method of any one of embodiments 1 to 61, the unit comprising:

[0238] -Reaction zone Z1, including

[0239] - An inlet device for conveying airflow G1 into Z1;

[0240] -Catalyst C1;

[0241] - A reaction apparatus for bringing gas stream G1 into contact with the catalyst C1;

[0242] - An outlet device for removing airflow GP from Z1;

[0243] - Material flow splitting device S, used to split airflow GP into at least two material flows, preferably two material flows including airflow GR and airflow G2;

[0244] - A means for conveying airflow GP into the device S;

[0245] - At least one, preferably two, devices M, for preparing G1 into a mixture comprising at least two streams, preferably consisting of at least two streams;

[0246] - Return device R, used to transfer the airflow GR from S into the device M for preparing G1.

[0247] 63. The preparation unit according to embodiment 62, wherein the reaction device of reaction zone Z1 is a reactor, preferably a tubular reactor containing one or more tubes, and more preferably a tube bundle reactor.

[0248] 64. The preparation unit according to embodiment 63, wherein the tubular reactor comprises one or more tubes and the catalyst C1 is contained in the one or more tubes.

[0249] 65. The preparation unit according to embodiment 63 or 64, wherein the tubular reactor comprises 1 to 10,000 tubes, preferably 1,000 to 9,000 tubes.

[0250] 66. The preparation unit according to any one of embodiments 63 to 65, wherein the length of the tube of the tubular reactor is in the range of 1.5 to 12 m, preferably in the range of 1.8 to 10 m, and more preferably in the range of 1.9 to 5 m.

[0251] 67. The preparation unit according to any one of embodiments 63 to 66, wherein one or more tubes of the tubular reactor, preferably the tubes of the tubular reactor, have an inner diameter in the range of 20 to 90 mm, more preferably in the range of 30 to 60 mm, and more preferably in the range of 35 to 50 mm.

[0252] 68. The preparation unit according to any one of embodiments 63 to 67, wherein one or more tubes of the tubular reactor, preferably the tubes of the tubular reactor, have a wall thickness in the range of 2.0 to 4.0 mm, preferably in the range of 2.5 to 3.0 mm.

[0253] 69. The preparation unit according to any one of embodiments 63 to 68, wherein one or more tubes of the tubular reactor, preferably the tubes of the tubular reactor, are made of a corrosion-resistant material, preferably an iron-based alloy, a nickel-based alloy or nickel, more preferably duplex steel 1.4462, stainless steel 1.4571 or stainless steel 1.4541.

[0254] 70. The preparation unit according to any one of embodiments 62 to 69, wherein the reaction apparatus for the reaction zone Z1 is cooled, preferably by one or more of water and monochlorobenzene, more preferably by monochlorobenzene, wherein the reaction apparatus for the reaction zone Z1 is a cooled tubular reactor.

[0255] 71. The preparation unit according to embodiment 70, wherein the cooling reactor includes one or more cooling zones, more preferably one or two cooling zones.

[0256] 72. The preparation unit according to embodiment 62, wherein the reaction apparatus of reaction zone Z1 is a non-cooled reaction apparatus, and reaction zone Z1 further includes a cooling device located downstream of the reaction apparatus zone.

[0257] 73. The preparation unit according to embodiment 72, wherein the return device R further includes a cooling device.

[0258] 74. The preparation unit according to embodiment 72 or 73, wherein the non-cooled reaction device is an adiabatic fixed-bed reactor.

[0259] 75. The preparation unit according to any one of embodiments 62 to 74, wherein the return device R is a return pipe, preferably an external return pipe to reactor Z1 or an internal return pipe to reactor Z1, more preferably an external return pipe.

[0260] 76. The preparation unit according to embodiment 75, wherein the inner diameter of the return tube is in the range of 100 to 500 mm, more preferably in the range of 150 to 300 mm.

[0261] 77. The preparation unit according to embodiment 75 or 76, wherein the return tube is made of a corrosion-resistant material, preferably of an iron-based alloy, a nickel-based alloy, or nickel, and more preferably of duplex steel 1.4462, stainless steel 1.4571, or stainless steel 1.4541.

[0262] 78. A preparation unit according to any one of embodiments 62 to 77, wherein the unit comprises two devices M for preparing G1 into a mixture comprising at least two streams, preferably at least two streams, wherein device M(e) is an injector for mixing GR and gas flow G0(k), and device M(s) is a static mixer.

[0263] 79. The preparation unit according to embodiment 78, wherein device M(s) is located upstream of device M(e), wherein device M(s) is a static mixer for merging G0(1) and G0(2), and device M(e) is an injector for mixing GR with the merged G0(1) and G0(2).

[0264] 80. The preparation unit according to embodiment 78, wherein device M(e) is located upstream of device M(s), wherein device M(e) is an injector for mixing GR with G0(1) or G0(2), and device M(s) is a static mixer for merging another of G0(1) and G0(2) with the mixed G0(1) or G0(2).

[0265] 81. The preparation unit according to any one of embodiments 62 to 80 further includes:

[0266] -Reaction zone Z2, including

[0267] - An inlet device for conveying airflow G2 into Z2;

[0268] -Catalyst C2;

[0269] - A reaction apparatus for bringing gas stream G1 into contact with the catalyst C2;

[0270] - An outlet device for removing airflow GF from Z2.

[0271] 82. The preparation unit according to embodiment 81, wherein the reaction device of reaction zone Z2 is a reactor, preferably a tubular reactor including one or more tubes, and more preferably a tube bundle reactor.

[0272] 83. The preparation unit according to embodiment 82, wherein the tubular reactor comprises one or more tubes and the catalyst C2 is contained in one or more tubes.

[0273] 84. The preparation unit according to embodiment 82 or 83, wherein the tubular reactor comprises 1 to 10,000 tubes, preferably 1,000 to 9,000 tubes.

[0274] 85. The preparation unit according to any one of embodiments 82 to 84, wherein one or more tubes of the tubular reactor, preferably the tubes of the tubular reactor, have a length in the range of 1.5 to 12 m, more preferably in the range of 1.8 to 10 m, and more preferably in the range of 1.9 to 5 m.

[0275] 86. The preparation unit according to any one of embodiments 82 to 85, wherein one or more tubes of the tubular reactor, preferably the tubes of the tubular reactor, have an inner diameter in the range of 20 to 90 mm, more preferably in the range of 30 to 60 mm, and more preferably in the range of 35 to 50 mm.

[0276] 87. The preparation unit according to any one of embodiments 82 to 86, wherein one or more tubes of the tubular reactor, preferably the tubes of the tubular reactor, have a wall thickness in the range of 2.0 to 4.0 mm, preferably in the range of 2.5 to 3.0 mm.

[0277] 88. The preparation unit according to any one of embodiments 82 to 87, wherein one or more tubes of the tubular reactor, more preferably tubes of the tubular reactor, are made of a corrosion-resistant material, preferably made of an iron-based alloy, a nickel-based alloy or nickel, more preferably made of duplex steel 1.4462, stainless steel 1.4571 or stainless steel 1.4541.

[0278] 89. The preparation unit according to any one of embodiments 81 to 88, wherein the reaction apparatus of reaction zone Z2 is cooled by a coolant medium, wherein the coolant medium is one or more of water and monochlorobenzene, more preferably monochlorobenzene, wherein the reaction apparatus of reaction zone Z2 is a cooled tube bundle reactor.

[0279] 90. The preparation unit according to any one of embodiments 81 to 89, wherein the surface loading of phosgene obtained by the preparation unit is between 0.5 and 6 kg / m³. 2 Within the range of s, preferably 0.7 to 5 kg / m 2 More preferably, within the range of 0.7 to 4 kg / m 2Within the range of s, more preferably from 0.8 to 3.5 kg / m 2 Within the range of s.

[0280] 91. The preparation unit according to any one of embodiments 81 to 90 further includes a device for condensing the phosgene in the gas stream GF.

[0281] 92. The preparation unit of any one of embodiments 62 to 91 or the method of any one of embodiments 1 to 61 is used for the continuous preparation of phosgene.

[0282] In the context of this invention, the term "one or more of A, B, and C" is intended to disclose A, or B, or C, or A and B, or A and C, or B and C, or A, B, and C. In this regard, it should be noted that those skilled in the art can transfer the above abstract terms to concrete examples, such as A, B, and C being concrete elements, such as Li, Na, and K. It should also be noted that those skilled in the art can extend the above terms to less specific implementations of the described features, for example, "one or more of A and B" discloses A, or B, or A and B.

[0283] In the context of this invention, the terms "total pore volume of a porous material" and "total pore volume" refer to the sum of the volume of the mesopores and the volume of the micropores in a porous material.

[0284] In the context of this invention, the total pore volume of a porous material is the sum of the volume of the mesopores and the volume of the micropores in the porous material.

[0285] In the context of this invention, the total specific surface area of ​​the porous material is preferably determined by dual isothermal NLDFT advanced pore size distribution (Micromeritics ASAP 2020_Micromeritics Instrument Corp., Norcross, GA, USA). NLDFT surface area is expressed in m³ / s. 2 / g expression. The NLDFT Advanced Pore Size Distribution technique uses up to two inert gases, namely nitrogen and carbon dioxide, to measure the amount of gas adsorbed on a material and can be used to determine the accessible surface area of ​​a given material.

[0286] Furthermore, in the context of this invention, the total pore volume of the porous material is preferably determined by dual isotherm NLDFT advanced pore size distribution (Micromeretics ASAP 2020_Micromeretics Instrument Corp., Norcross, GA, USA). The total pore volume is expressed in ml / g. The NLDFT advanced pore size distribution technique uses up to two inert gases, namely nitrogen and carbon dioxide, to measure the amount of gas adsorbed on a given material and can be used to determine the total pore volume of the given material. Similarly, the volume of pores (mesopores, micropores) within a certain pore size range is determined by the same method. Therefore, the volume of mesopores and the volume of micropores in the porous material are determined by dual isotherm NLDFT advanced pore size distribution (Micromeretics ASAP 2020).

[0287] In the context of this invention, the term "BET specific surface area" refers to the total specific surface area of ​​a material (e.g., a porous material) that can be measured using BET technology. BET specific surface area is expressed in m³. 2 / g represents the area. For example, the BET specific surface area can be determined by the BET (Brunauer / Emmett / Teller) method using a Micrometries ASAP 2420 device to physically adsorb nitrogen (liquid nitrogen) at -196°C.

[0288] In the context of this invention, it should be noted that the multi-point thermocouple used to measure the temperature of a given gas in the reaction tube is of the type described in DE 10110847 A1.

[0289] The present invention will be further illustrated by the following Examples 1 to 5 and Figures 2 to 6.

[0290] Example

[0291] The multipoint thermocouples used below are as described in DE 10110847 A1.

[0292] Reference Example 1: Preparation of Carbon-Containing Catalyst

[0293] Catalysts (porous carbon materials) 5 and 7 are prepared by a method defined in WO 2012 / 092210 A1: A method for preparing such high surface area activated carbon materials is to prepare synthetic polymers (e.g., polymer gels) from carbon-containing organic structural units. For example, changing the polymerization and gelation conditions (temperature, duration, etc.) allows for the acquisition of different catalysts. Similar to existing organic materials, the synthetically prepared polymer is dried (e.g., by evaporation or freeze-drying), pyrolyzed, and activated to prepare activated carbon materials (e.g., aerogels or dry gels). Therefore, the method for preparing catalysts 4 to 7 (porous materials containing carbon, micropores, and mesopores (pyrolytic carbon aerogels)) includes:

[0294] A mixture comprising a solvent (water / acetic acid), a catalyst (ammonium acetate catalyst), a first monomer (resorcinol), and a second monomer (formaldehyde) is prepared.

[0295] The first monomer in the mixture is copolymerized with the second monomer to obtain a resin mixture;

[0296] The obtained resin mixture is cured at a curing temperature (e.g., 95°C) to obtain a polymer composition comprising a solvent and a polymer formed by copolymerization of a first monomer and a second monomer, wherein the solvent concentration in the polymer composition is at least 40% by weight, based on the total weight of the polymer composition; and

[0297] The obtained polymer composition is pyrolyzed at a pyrolysis temperature to substantially remove the solvent and pyrolyze the polymer to obtain a carbon material. Alternatively, the method includes:

[0298] A mixture comprising a solvent (water / acetic acid), a catalyst (ammonium acetate catalyst), a first monomer (resorcinol), and a second monomer (formaldehyde) is prepared, and the reaction mixture is maintained at the reaction temperature for the duration of the reaction.

[0299] The first and second monomers of the obtained mixture are copolymerized to obtain a resin mixture;

[0300] The obtained resin mixture is cured at a curing temperature (e.g., 95°C) to obtain a polymer composition comprising a solvent and a polymer formed by copolymerization of a first monomer and a second monomer.

[0301] The obtained polymer composition is pyrolyzed at a pyrolysis temperature to substantially remove the solvent and pyrolyze the polymer to obtain a carbon material; and

[0302] Optionally, the carbon material is activated at an activation temperature, thereby increasing the surface area and pore volume to the desired level to obtain porous carbon materials 5 and 7. Curing is carried out at an elevated temperature, for example, about 95°C.

[0303]

[0304] Comparative Example 1: Preparation of Phosgene Not Based on the Invention

[0305] A reaction tube with an inner diameter of 39.3 mm and a length of 2 m was filled with 4 mm activated carbon extrudate from Donau Carbon. A feed containing CO and Cl2 was fed into the reaction tube of the system for preparing phosgene, operating at an inlet pressure of 4 bar, corresponding to 3 kg phosgene / m³. 2 The loading of s was 5% in molar excess of CO. Monochlorobenzene was used, and the reaction tube was cooled to 80°C. The chlorine conversion rate was approximately 97.6%. The temperature distribution within the reaction tube was measured using multi-point thermocouples. The hot spot temperature was approximately 590°C. The temperature profile within the tube is shown in Figure 1. The CCl4 concentration at the outlet of the reaction tube (measured by online GC) was approximately 83 vol-ppm.

[0306] Example 1: Preparation of Phosgene according to the present invention

[0307] To prepare phosgene of Example 1, the system and method for preparing phosgene of Comparative Example 1 were used, except that a portion of the product gas stream obtained at the outlet of the reaction tube was recirculated; this portion (GR) was equivalent to 45% of the initial feed gas stream. Recirculation involved drawing this portion in through an injector and mixing it into the feed stream. The injector was located upstream of the inlet of the reaction tube (f(GR):f(G2) = 0.45:1 and f(GR):f(GP) = 0.31:1). The system used for preparing phosgene is shown in Figure 2. Compared to the hot spot obtained using the method of Comparative Example 1, the hot spot temperature decreased to 407°C, and the chlorine conversion rate was 93.7%. The temperature profile inside the tube is shown in Figure 1. The CCl4 concentration at the outlet of the reaction tube was below the detection limit of 1 vol-ppm.

[0308] Typical preparation units for implementing the method of Example 1 include: Figure 2a As shown (93.7% chlorine conversion rate was obtained after passing through reaction zone Z1).

[0309] Example 2: Preparation of Phosgene according to the present invention

[0310] To prepare phosgene of Example 2, the system and method for preparing phosgene of Example 1 were used, except that the activated carbon catalyst from Donau Carbon was replaced with an activated carbon catalyst prepared as described in Reference Example 1, and a larger portion equivalent to 62% of the initial feed gas flow rate was recirculated (f(GR):f(G2) = 0.62:1 and f(GR):f(GP) = 0.383:1) to control the hot spot temperature at 408°C, which is comparable to the hot spot obtained using Example 1. The recirculation involved drawing this portion in and mixing it into the feed stream through an injector located upstream of the inlet end of the reaction tube. Compared to the method of Comparative Example 1, the chlorine conversion rate increased to 98.9%. The temperature profile inside the tube is shown in Figure 1. The CCl4 concentration at the reactor outlet remained below the detection limit of 1 vol-ppm.

[0311] The temperature curves obtained from Comparative Example 1, Example 1, and Example 2 are shown in Figure 1.

[0312] Example 3: Preparation of Phosgene according to the present invention

[0313] The method of Example 3 prepared 39 t / h of phosgene. The corresponding feed stream (28 t / h of chlorine and 11.6 t / h of CO) was pre-pressurized at 8 bara and initially used as the driving force in the ejector. This means that approximately 241 t / h of reaction gas at 4 bara was drawn in from the outlet end of an uncooled fixed bed (adiabatic fixed bed reactor) with a diameter of 4.7 m and a length of approximately 3.6 m, filled with 4 mm of activated carbon extrudate (from Donau Carbon), and cooled in a heat exchanger so that the inlet temperature of the gas mixture of feed gas and recirculated product gas was approximately 75 °C and compressed to 4.5 bara by the ejector. The chlorine conversion was approximately 95%, wherein the gas was adiabatic heated to only 300 °C (hot spot temperature). The temperature distribution in the uncooled fixed bed was measured using multi-point thermocouples. The unrecirculated portion of the product gas was fed into a cooled reactor downstream of the uncooled fixed bed, where complete chlorine conversion was achieved. A schematic diagram of the preparation unit used in Example 3 is shown below. Figure 4 As shown.

[0314] For the method in Example 3, f(GR):f(G2)=241t / h:(28+11.6)t / h=241:39.6=6:1 and f(GR):f(GP)=241t / h:(241+39.6)t / h=0.86:1.

[0315] Example 4: Preparation of Phosgene according to the present invention

[0316] Large-scale preparation was carried out as follows. A standard cooled reactor (fixed bed—2849 tube—inner tube diameter: 39.3 mm—filled tube length: 3.8 m—4 mm activated carbon extrudate—catalyst 7 or 5 as described in Reference Example 1) was used, and the necessary amount of phosgene was introduced upstream of the reactor for dilution via an external reflux pipe of 200 mm diameter and an injector driven by a fresh feed containing a mixture of Cl2 and excess (10%) CO. After thorough mixing in a static mixer, the entire gas stream was introduced into the reactor.

[0317] Table 2

[0318] Example 4 <![CDATA[Cl2 feed gas stream]]> kg / h 26767.9 CO feed gas stream kg / h 11612 Phosgene flow kg / h 35500 CO excess ％ 10 Inlet gas temperature ℃ 62 Inlet gas pressure bara 4.9 Coolant inlet temperature ℃ 75 Coolant outlet temperature ℃ 86

[0319] Comparative Example 2: Preparation of Phosgene Not Based on the Invention

[0320] A reaction tube with an inner diameter of 39.3 mm and a length of 2 m was filled with 4 mm of activated carbon catalyst, which differed from the one used in the examples and comparative examples described above. A feed of CO (9.4 kg / h) and Cl2 (4.1 kg / h) – with a 10% CO molar excess – was fed into the reaction tube of the system used for phosgene preparation, operating at an inlet pressure of 3.7 barg (bar gauge). The reaction tube was cooled at 80°C using monochlorobenzene. The chlorine conversion rate was approximately 96.6%. The temperature distribution within the reaction tube was measured using multi-point thermocouples. The hot spot temperature was approximately 562°C. The temperature profile within the tube is shown below. Figure 7 As shown. The CCl4 concentration at the outlet of the reaction tube (measured by online GC) was approximately 24 vol-ppm.

[0321] Comparative Example 3: Preparation of Phosgene Not Based on the Invention

[0322] To prepare phosgene in Comparative Example 3, the system and method for preparing phosgene in Comparative Example 2 were used, except that the product gas stream obtained at the outlet of the reaction tube was cooled and partially condensed in a downstream condenser, as described in US2011 / 0319662. The condenser was operated at -10°C and 3.5 barg. The exhaust gas from the condenser was taken away at 5 kg / h and recycled back, mixed with the reactor feed stream before entering the reactor inlet. The recirculated gas stream contained 89.2 mol% CO and 10.8 mol% COCl2, a composition different from the gas stream exiting the reactor. The temperature distribution in the reaction tube was measured using multi-point thermocouples. The hot spot temperature was approximately 466°C; therefore, the hot spot temperature was lower than that obtained in the Comparative Example due to dilution of the feed stream. The temperature profile inside the tube is shown below. Figure 7As shown. The chlorine conversion rate is approximately 99.1%. The CCl4 concentration at the outlet of the reaction tube (measured by online GC) is approximately <1 vol-ppm.

[0323] Example 5: Preparation of Phosgene according to the present invention

[0324] To prepare phosgene in Example 5, the system and method for preparing phosgene in Comparative Example 2 were used, except that a portion (GR) of the product gas stream (GP) obtained at the outlet of the reaction tube was recirculated and mixed with the reactor feed stream before entering the reactor inlet. The recirculated gas stream (GR) contained 9.1 mol% CO and 90.9 mol% COCl2, and its composition was the same as that of the gas stream (GP). The hot spot temperature decreased to 428°C compared to the hot spot temperature obtained using the method of Comparative Example 2, which did not include any recirculation, and the hot spot temperature obtained using the method of Comparative Example 3, which included different recirculation. The chlorine conversion rate was 93%. The temperature profile inside the tube is shown below. Figure 7 As shown, the CCl4 concentration at the outlet of the reaction tube was below the detection limit of 1 vol-ppm.

[0325] For the method in Example 5, f(GR) = 5 kg / h; f(G2) = 13.5 kg / h; f(GR):f(G2) = 0.37:1 and f(GR):f(GP) = 5:(5+13.5) kg / h = 0.27:1.

[0326] The temperature curves obtained in Comparative Examples 2 and 3 and Example 5 are as follows: Figure 7 As shown. The results show that the method of the present invention is better than that of Comparative Examples 2 and 3; compared with Comparative Example 2, the hot spot temperature is greatly reduced and the CCl4 concentration at the outlet of the reaction tube is greatly reduced; compared with Comparative Example 3, it is not necessary to cool the recirculated feed stream to -10°C, which allows for energy savings and thus reduces costs. Attached Figure Description

[0327] Figure 1a : indicates the temperature curve obtained when preparing phosgene using the method of Comparative Example 1 and the method of Example 1.

[0328] Figure 1b : indicates the temperature curve obtained when preparing phosgene using the methods of Example 1 and Example 2.

[0329] Figure 2aThis is a schematic diagram of a preparation unit according to an embodiment of the present invention. The preparation unit includes: a reaction zone Z1, which includes an inlet device (e.g., a pipe) for introducing a gas stream G1 into Z1; and a reaction device (cooling reactor) for contacting the gas stream G1 with a catalyst C1 (preferably a carbon-containing catalyst, not shown in the figure). The cooling reactor is a tubular reactor comprising one or more tubes, preferably more than one tube, and preferably a cooled tube bundle reactor. This reactor is cooled with a heat transfer / cooling medium, preferably monochlorobenzene. The inlet temperature of the coolant medium is in the range of 60 to 100°C. The highest gas stream temperature in the reactor is set to 400°C (hot spot). Furthermore, the reaction zone Z1 includes an outlet device, such as a pipe, for removing the gas stream GP from Z1. The gas stream GP contains phosgene, and one or more of carbon monoxide and chlorine. At the outlet end of reaction Z1, 90-100% of the chlorine is converted. The preparation unit also includes a splitting device for dividing the gas stream GP into two streams (gas stream GR and gas stream G2), and a device (e.g., a pipe) for conveying the gas stream GP into the splitting device (not shown in the figure). Gas streams G2 and GR have the same chemical composition as GP. The temperature of gas streams GP, GR, and G2 is 80 ± 5 °C. Such a temperature may be in the range of 60 to 100 °C. The preparation unit also includes a device E, preferably an injector, for mixing gas stream G0 (G0(1) + G0(2)) with gas stream GR. The device E includes an inlet device, such as a pipe, for feeding gas stream G0 into E, and a device for feeding gas stream GR into E. Gas stream G0 consists of CO and Cl2, with CO in excess at 5%. Gas streams G0(1) and G0(2), not shown in the figure, are mixed in a static mixer upstream of the injector E. The recirculation ratio is the ratio of the mass flow rate f(GR) of the airflow GR to the mass flow rate f(GP) of the airflow GP, f(GR):f(GP), which is in the range of 0.2:1 to 0.8:1, preferably in the range of 0.3:1 to 0.7:1, and more preferably in the range of 0.35:1 to 0.6:1. The preparation unit also includes a return device R and a return pipe for transferring the airflow GR from the splitting device to the device E. Phosgene is at 3 kg / m³. 2 Prepared under surface load of s.

[0330] Figure 2b : is a schematic diagram of the preparation unit of an embodiment of the present invention. Figure 2b The preparation unit includes Figure 2a The components differ in that, for the preparation of G1, G0(1) (CO gas flow) drives the injector E, where the gas flow GR is mixed, and G0(2) is incorporated downstream of the injector E.

[0331] Figure 3 : is a schematic diagram of the preparation unit in the embodiment of the present invention. Figure 3The preparation unit includes the components shown in Figure 2 and also includes a reaction zone Z2, which includes an inlet device, such as a pipe, for conveying gas stream G2 into Z2. The reaction zone Z2 includes a reaction apparatus (preferably a cooled reactor) for contacting gas stream G1 with catalyst C2 (preferably a carbon-containing catalyst), and an outlet device (e.g., a pipe) for removing gas stream GF from Z2. The cooled reactor is a tubular reactor containing one or more tubes, preferably more than one tube, and more preferably a cooled tube bundle reactor. This reactor is cooled with a heat transfer / cooling medium, preferably monochlorobenzene. Alternatively, an adiabatic fixed bed can be used as the reaction apparatus in the reaction zone Z2. The gas stream GF contains phosgene. At the outlet end of the reaction zone Z2, more than 99.5% of the chlorine is converted. Phosgene is present at approximately 3 kg / m³. 2 Prepared under surface load of s.

[0332] Figure 4This is a schematic diagram of the preparation unit according to an embodiment of the present invention. The preparation unit includes a reaction zone Z1, which includes an inlet device (e.g., a pipe) for conveying gas stream G1 into Z1, and a reaction device (non-cooled reactor) for contacting gas stream G1 with catalyst C1 (preferably a carbon-containing catalyst, not shown in the figure). The temperature of gas stream G1 is 75°C. The non-cooled reactor is an adiabatic fixed-bed reactor. The reactor has a diameter of 4.7 m and a length of 3.6 m, and is filled with 4 mm of carbon extrudate (from DO-NAU CARBON). The highest gas stream temperature in the reactor is approximately 300°C (hot spot). In addition, the reaction zone Z1 includes an outlet device, such as a pipe, for removing gas stream GP from Z1. Gas stream GP contains phosgene, and one or more of carbon monoxide and chlorine. At the outlet end of reaction Z1, 95% of the chlorine is converted. The preparation unit also includes a splitting device S for splitting gas stream GP into two streams (gas stream GR and gas stream G2), and a device (e.g., a pipe) for conveying gas stream GP into S. Gas streams G2 and GR have the same chemical composition as GP. The temperature of gas streams GP, GR, and G2 is 300°C. The preparation unit also includes a device E, preferably an injector, for mixing gas stream G0 and gas stream GR. The device E includes an inlet device (e.g., a pipe) for feeding gas stream G0 (G0(1) + G0(2)) into E, and a return device for feeding gas stream GR into E. Gas stream G0 consists of CO and Cl2 and has a pressure P0 of 8 bara. The recirculation ratio is the ratio of the mass flow rate f(GR) of gas stream GR to the mass flow rate f(GP) of gas stream GP, f(GR):f(GP), which can be in the range of 0.20:1 to 0.95:1, preferably in the range of 0.50:1 to 0.92:1, and more preferably in the range of 0.70:1 to 0.90:1. In this case, f(GR):f(GP) = 0.86:1. The preparation unit also includes a return device R and a return pipe for conveying the gas stream GR from the splitting device into the device E and the heat exchanger H. The return pipe R is divided into two pipes R1 and R2, with pipe R1 exiting the device S toward the heat exchanger H and pipe R2 exiting the heat exchanger toward the inlet end of the device E. The gas stream GR has a pressure PR of approximately 4 bara. The gas stream G1 has a temperature of approximately 75°C and a pressure of 4.5 bara. The preparation unit also includes a reaction zone Z2 downstream of the device S. This zone, not shown in the figures, includes an inlet device, such as a pipe, for conveying the gas stream G2 into Z2. The reaction zone Z2 includes a reaction device (cooled reactor) for contacting the gas stream G1 with the catalyst C2 (preferably a carbon-containing catalyst), and an outlet device (e.g., a pipe) for removing the gas stream GF from Z2. The cooling reactor is a tubular reactor comprising one or more tubes, preferably more than one tube, and more preferably a cooled tube bundle reactor.This reactor is cooled by a heat transfer medium, preferably monochlorobenzene. The gas stream GF contains phosgene. At the outlet of reaction zone Z2, 100% of the chlorine is converted. Phosgene is prepared at a load of 39 t / h.

[0333] Figure 5 : This is a schematic diagram of the preparation unit according to an embodiment of the present invention. The preparation unit includes an inlet device for conveying gas stream G1 to Z1, and a reaction device (non-cooled reactor R1) for contacting gas stream G1 with catalyst C1 (preferably a carbon-containing catalyst, not shown in the figure). The adiabatic bed has a diameter of 4.7 m and a length of 3.6 m, and is filled with 4 mm of carbon extrudate. The highest gas stream temperature in the reactor is up to 400°C (hot spot), preferably 300°C. Furthermore, the reaction zone Z1 includes an outlet device for removing gas stream GP from Z1. Gas stream GP contains phosgene, and one or more of carbon monoxide and chlorine. Gas stream GP is fed directly to a cooling device, where multiple cooling tubes C are cooled with a coolant medium (e.g., monochlorobenzene). At the outlet end of the cooling tubes C, a splitting device (not shown in the figure) divides the "cooled" gas stream GP into two streams, namely gas stream GR and gas stream G2. Gas streams G2 and GR each have the same chemical composition as GP. The temperature of gas streams GP, GR, and G2 is approximately 75°C. The preparation unit also includes a device E, preferably an injector, for mixing gas stream G0 (G0(1) + G0(2)) and gas stream GR. Device E includes an inlet device (e.g., a pipe) for feeding gas stream G0 into E, and a device for feeding gas stream GR into E. Device E, reactor R1, and multiple pipes C are all housed in a single casing. Gas stream G0 consists of CO and Cl2. The flow rate ratio of gas stream GR to gas stream GP is in the range of 0.2:1 to 0.909:1, preferably in the range of 0.3:1 to 0.7:1, and more preferably in the range of 0.35:1 to 0.6:1. The preparation unit also includes a reaction zone Z2. This zone (not shown in the figures) includes an inlet device, such as a pipe, for conveying gas stream G2 into Z2. Reaction zone Z2 includes a reaction device (cooling reactor) for contacting gas stream G1 with catalyst C2 (preferably a carbon-containing catalyst), and an outlet device (e.g., a pipe) for removing gas stream GF from Z2. The cooling reactor is a tubular reactor comprising one or more tubes, preferably more than one tube, and more preferably a cooled tube bundle reactor. This reactor is cooled by a cooling medium, preferably monochlorobenzene. The gas stream GF contains phosgene. At the outlet end of reaction zone Z2, 100% of the chlorine gas is converted.

[0334] Figure 6 This is a schematic diagram of the preparation unit according to an embodiment of the present invention. The preparation unit in the diagram is as follows: Figure 2aThe preparation unit differs in that the cooling reactor includes a different cooling system, i.e., it has two cooling zones. In the figure, L represents the length of the cooling pipe of the reactor, L1 represents the length of the first cooling zone of the reactor operating at a higher temperature, and L2 represents the length of the second cooling zone of the reactor used for final cooling. Preferably, 1m ≤ L2 ≤ 1.5m, more preferably L2 = 1.3m. Further, a represents the inlet of the coolant medium used in the first cooling zone, b represents the outlet of the coolant medium used in the first cooling zone, c represents the inlet of the coolant medium used in the second cooling zone, and d represents the inlet of the coolant medium used in the second cooling zone. It is now believed that this configuration with two zones will allow for savings in the heat generated in the reaction zone Z1 used to prepare high-value steam. The first cooling zone can operate, for example, at a temperature range of 200 to 300°C, preferably about 250°C. As the heat transfer oil flows through the first cooling zone, the heat generated by the reaction of catalyst C1 in the reactor of reaction zone Z1 can be removed from the reactor of reaction zone Z1. Therefore, the oil recovered from the first cooling zone can be used to heat the solvent (e.g., water) in another heat exchanger (outside the preparation unit for phosgene). The second cooling zone can operate under normal conditions, i.e., at approximately 80°C. Reactors with more than one cooling zone can be as described in WO 03 / 072237A1.

[0335] Figure 7 : indicates the temperature curves obtained when preparing phosgene using the methods of Comparative Examples 2 and 3 and the method of Example 5.

[0336] References

[0337] - Christopher J. Mitchell et al., Selection of carbon catalysts for the industrial manufacture of phosgene, Hunterman Polyurethanes, Catal. Sci. Technol., 2012, 2109-2115;

[0338] -WO 2012 / 092210 A1;

[0339] - Ullmann's Encyclopedia of Industrial Chemistry, chapter on "Phosgene", 5th edition, Vol. A19, p. 413 and below, VCH Verlagsgesellschaft mbH, Weinheim, 1991;

[0340] -WO 03 / 072237A1;

[0341] -DE 10110847 A1.

Claims

1. A continuous method for preparing phosgene, comprising: (i) Provide an airflow G1 containing carbon monoxide (CO) and chlorine (Cl2); (ii) A gas flow G1 is introduced into the reaction zone Z1, so that the gas flow G1 comes into contact with the catalyst C1 contained in the reaction zone Z1 to obtain a gas flow GP containing phosgene, and one or more of carbon monoxide and chlorine, and the gas flow GP is removed from the reaction zone Z1. (iii) Split the airflow GP to obtain at least two airflows including airflow G2 and airflow GR, wherein G2 and GR have the same chemical composition as GP, and the ratio of the mass flow rate f(GR) of airflow GR to the mass flow rate f(G2) of airflow G2, f(GR):f(G2), is in the range of 0.1:1 to 20:

1. During the standard operating mode of the continuous method, the airflow G1 provided according to (i) includes: G1 is prepared as a mixture comprising at least two gas streams, the at least two gas streams comprising gas stream GR and j gas streams G0(k), where k = 1, ... j, wherein the j gas streams G0(k) generally comprise carbon monoxide (CO) and chlorine (Cl2) and wherein j is in the range of 1 to 3.

2. The method according to claim 1, wherein j is 1 or 2.

3. The method according to claim 2, wherein j is 2.

4. The method according to any one of claims 1 to 3, wherein f(GR):f(G2) is in the range of 0.2:1 to 10:

1.

5. The method of claim 4, wherein f(GR):f(G2) is in the range of 0.25:1 to 4:

1.

6. The method of claim 5, wherein f(GR):f(G2) is in the range of 0.3:1 to 3:

1.

7. The method of claim 6, wherein f(GR):f(G2) is in the range of 0.3:1 to 1.5:

1.

8. The method of claim 4, wherein f(GR):f(G2) is in the range of 5:1 to 8:

1.

9. The method according to any one of claims 1 to 3, wherein during the standard operating mode of the continuous method, providing airflow G1 according to (i) comprises: G1 is prepared as a mixture of three gas streams, the three gas streams being gas stream GR and two gas streams G0(1) and G0(2), wherein the two gas streams G0(1) and G0(2) contain carbon monoxide (CO) and chlorine (Cl2) in general.

10. The method according to claim 9, wherein the mixture is a mixture of three gas streams, the three gas streams being gas stream GR and two gas streams G0(1) and G0(2).

11. The method according to any one of claims 1 to 3, wherein during the standard operating mode of the continuous method, providing airflow G1 according to (i) comprises: G1 was prepared as a mixture containing three gas streams: GR, G0(1), and G0(2), wherein G0(1) contained carbon monoxide (CO) and G0(2) contained chlorine gas (Cl2). - Combine airflow G0(1) with airflow G0(2), and - Mix the airflow GR with the combined airflows G0(1) and G0(2).

12. The method according to claim 11, wherein G1 is prepared as a mixture of three gas streams GR, G0(1) and G0(2).

13. The method of claim 11, wherein the merging is performed in a static mixer.

14. The method of claim 11, wherein, according to (i), the mixing of the airflow GR with the two combined airflows G0(1) and G0(2) is carried out in a mixing device, wherein the mixing device is an injector, a static mixer or a dynamic mixer.

15. The method of claim 14, wherein the mixing device is an injector.

16. The method according to claim 11, wherein in the combined gas streams G0(1) and G0(2), the molar ratio of chlorine to carbon monoxide is in the range of 0.6:1 to 0.999:

1.

17. The method of claim 16, wherein the molar ratio of chlorine to carbon monoxide is in the range of 0.7:1 to 0.

98.

18. The method of claim 17, wherein the molar ratio of chlorine to carbon monoxide is in the range of 0.85:1 to 0.95:

1.

19. The method according to any one of claims 1 to 3, wherein during the standard operating mode of the continuous method, providing airflow G1 according to (i) comprises: G1 was prepared as a mixture containing three gas streams: GR, G0(1), and G0(2), wherein G0(1) contained carbon monoxide (CO) and G0(2) contained chlorine gas (Cl2). - Mix the airflow G0(1) with the airflow GR, and - Combine airflow G0(2) with mixed airflow G0(1) and GR.

20. The method of claim 19, wherein the mixture is a mixture of three gas streams GR, GO(1) and GO(2).

21. The method of claim 19, wherein the merging is performed in a static mixer.

22. The method according to any one of claims 1 to 3, wherein during the standard operating mode of the continuous method, providing airflow G1 according to (i) comprises: G1 was prepared as a mixture containing three gas streams: GR, G0(1), and G0(2), wherein G0(1) contained carbon monoxide (CO) and G0(2) contained chlorine gas (Cl2). - Mix airflow G0(2) with airflow GR, and - Combine airflow G0(1) with mixed airflow G0(2) and GR.

23. The method according to claim 22, wherein the mixture is a mixture of three gas streams GR, GO(1) and GO(2).

24. The method of claim 22, wherein the merging is performed in a static mixer.

25. The method according to any one of claims 1 to 3, wherein the reaction zone Z1 comprises a reactor containing catalyst C1.

26. The method of claim 25, wherein the reactor is a tubular reactor comprising one or more tubes, and the catalyst C1 is filled in the one or more tubes.

27. The method of claim 25, wherein the gas flow in the reactor is at most 450°C.

28. The method of claim 27, wherein the gas flow in the reactor is at most 400°C.

29. The method of claim 28, wherein the gas flow in the reactor is at most 350°C.

30. The method of claim 27, wherein the temperature is measured using a multi-point thermocouple.

31. The method according to any one of claims 1 to 3, further comprising: Following (iii), the airflow GR is passed through the return device R and then, in the injector, during the standard operating mode of the continuous method, according to (i), G1 is prepared as a mixture containing at least two material streams.

32. The method of claim 31, wherein G1 is prepared as a mixture of at least two feed streams.

33. The method according to any one of claims 1 to 3, wherein catalyst C1 is a carbon catalyst.

34. The method according to claim 33, wherein catalyst C1 is an activated carbon catalyst.

35. The method of claim 33, wherein the catalyst C1 comprises a porous material comprising carbon, micropores and mesopores, wherein the micropores have a pore size of less than 2 nm; and wherein the mesopores have a pore size in the range of 2 nm to 50 nm; The volume of the mesopores in the porous material is at least 0.45 ml / g.

36. The method according to claim 35, wherein the catalyst C1 is the porous material.

37. The method according to claim 35, wherein the pore size of the micropores is determined according to DIN 66135-2.

38. The method according to claim 35, wherein the aperture of the central hole is determined according to DIN 66134.

39. The method of claim 35, wherein the volume of the mesopores in the porous material is determined using double isothermal nonlocal density functional theory (NLDFT) advanced pore size distribution (PSD) technique.

40. The method according to any one of claims 1 to 3, further comprising: (iv) The conveyor stream G2 enters the reaction zone Z2, so that the gas stream G2 comes into contact with the catalyst C2 contained in the reaction zone Z2 to obtain a gas stream GF containing phosgene, and the gas stream GF is removed from the reaction zone Z2.

41. A preparation unit for carrying out the method according to any one of claims 1 to 40, comprising: - Reaction zone Z1, including - An inlet device for conveying airflow G1 into Z1; - Catalyst C1; - A reaction apparatus for bringing gas stream G1 into contact with the catalyst C1; - An outlet device for removing the airflow GP from Z1; - A material flow splitting device S is used to split airflow GP into at least two material flows, including airflow GR and airflow G2; - A means for conveying airflow GP into the device S; - At least one device M for preparing G1 into a mixture comprising at least two feed streams; - Return device R, used to transfer the gas flow GR discharged from S into the device M used to prepare G1.

42. The preparation unit according to claim 41, wherein the material flow splitting device S is used to split the airflow GP into two material flows, airflow GR and airflow G2.

43. The preparation unit according to claim 41, wherein the preparation unit comprises two devices M.

44. The preparation unit according to claim 41, wherein the device M is used to prepare G1 as a mixture consisting of at least two feed streams.

45. Use of the preparation unit according to claim 41 for the continuous preparation of phosgene.

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