CN110803684B

CN110803684B - Method and device for preparing chlorine by hydrogen chloride photocatalytic oxidation

Info

Publication number: CN110803684B
Application number: CN201911181748.5A
Authority: CN
Inventors: 王农跃; 沙艳松; 章冬霞; 李斌
Original assignee: Jiangsu Fangyuan Aramid Research Institute Co ltd
Current assignee: Fangyuan New Material Technology Co ltd
Priority date: 2019-11-27
Filing date: 2019-11-27
Publication date: 2021-07-16
Anticipated expiration: 2039-11-27
Also published as: CN110803684A

Abstract

The application relates to the field of hydrogen chloride catalytic oxidation, and discloses a method and a device for preparing chlorine through hydrogen chloride photocatalytic oxidation, and the application separates a reactor into a light irradiation area and a no light irradiation area, wherein the light irradiation area can be irradiated by light, the no light irradiation area can not be irradiated by light, the wavelength of light is any value or range from 150nm to 278nm, and gas between the light irradiation area and the no light irradiation area can circulate, so that the product gas is effectively prevented from continuously generating reverse photolysis under the light irradiation condition, and the yield is improved.

Description

Method and device for preparing chlorine by hydrogen chloride photocatalytic oxidation

Technical Field

The application relates to the field of hydrogen chloride catalytic oxidation, in particular to a method and a device for preparing chlorine through hydrogen chloride photocatalytic oxidation.

Background

Chlorine is an important chemical product and raw material, and is mainly applied to the fields of polyvinyl chloride, MDI, TDI, methane chloride, synthetic rubber, silicon materials, chlorofluorocarbons, building materials, medicines and the like. The utilization rate of chlorine element is about 50% in the production process, and the hydrogen chloride gas with the same volume is usually produced as a byproduct. The problem of the out-route of a large amount of byproduct hydrogen chloride becomes a common problem which restricts the sustainable development of the industry related to chlorine. The byproduct hydrogen chloride is made into chlorine and is put into the production chain again, so that a circular economic reaction system of chlorine element can be constructed.

The conversion of byproduct hydrogen chloride into chlorine is mainly realized by 3 process methods, namely an electrolysis method, a direct oxidation method and a catalytic oxidation method. The electrolysis method has the defects of high energy consumption, high impurity content of products and the like, and is not developed. The direct oxidation method is to use a strong oxidant such as NO₂、SO₃Or HNO₃/H₂SO₄The mixed acid as an oxidant directly oxidizes hydrogen chloride, has complex equipment, high product separation difficulty and relatively high energy consumption, and cannot be popularized. The typical process of the catalytic oxidation method mainly comprises a Deacon process, and compared with an electrolysis method and a direct oxidation method, the catalytic oxidation method has the advantages of low energy consumption, simplicity and easiness in operation, high per pass conversion rate and the like, and is widely considered to be the method which is most easy to realize industrialization at present. However, the catalytic oxidation method has a high reaction temperature, which often causes the activity of the catalyst to be reduced and the service life to be shortened, so that the catalyst needs to be replaced frequently, and the cost is high.

In order to be able to lower the reaction temperature and to allow the reaction to proceed towards the product end, WO2017194537a1 provides for heterogeneous photocatalytic oxidation of hydrogen chloride by UV radiation, producing a gas mixture composed of at least hydrogen chloride, oxygen and optionally other minor constituents, and passing it over a solid photocatalyst comprising at least one photoactive material, such as a transition metal or a transition metal oxide or a semiconductor material, and initiating the reaction on the surface of the catalyst by the action of UV radiation in a selective energy range. In this method, the hydrogen chloride conversion rate can reach 90% or more, but a solid photocatalyst is required.

RU2253607 continuously feeds a reaction mixture of air and hydrogen chloride to a flow type reactor to form an activation zone, wherein the hydrogen chloride is oxidized with oxygen at a temperature ranging from 25 to 30 ℃, the activation zone is formed by irradiating the reaction mixture in a specific region of the reactor with a mercury high pressure quartz lamp having a volumetric irradiation density of (10-40). times.10 at a pressure of not more than 0.1MPa^-4W/cm³. JPS5973405 irradiates with pulsed coherent light, gaseous hydrogen chloride is caused to pass through a photochemical reaction in the presence of oxygen and/or air to generate chlorine gas, or coherent light and incoherent light are alternately used or pulsed irradiation of coherent light is performed during irradiation with incoherent light. WO2006132561A1 produces chlorine as oxygen for oxidizing hydrogen chloride at a wavelength of 165 to 270nm and a density of (10-40). 10 by continuously supplying a gaseous mixture containing hydrogen chloride and oxygen in a flow-through reaction zone and oxidizing the hydrogen chloride by oxygen to form a target product^-4W/cm³Is activated with ultraviolet irradiation, the pressure is kept at not more than 0.1MPa, or oxygen is activated under current irradiation of accelerated electrons having an energy of 100keV to 2 MeV.

The existing technology for oxidation by using photocatalytic hydrogen chloride can obtain higher conversion rate, but the feeding speed and pressure must be strictly controlled, and the heat balance of the reaction process is disturbed by overhigh or overlow feeding speed or pressure change, so that the conversion rate of the hydrogen chloride is obviously reduced. In the industrial production process, the realization of a larger conversion rate still has considerable difficulty and higher cost.

Disclosure of Invention

The present inventors have completed the present application in view of the above-mentioned shortcomings of the prior art. The application provides a method for preparing chlorine by photocatalytic oxidation of hydrogen chloride, which takes light as a catalyst and realizes high hydrogen chloride conversion rate by separating a reactor.

The inventor researches and discovers that the prior art hydrogen chloride photocatalytic oxidation method is difficult to realize industrialization, and has the main problem that H-Cl bond energy is larger than Cl-Cl bond energy, when hydrogen chloride is excited by using a light source irradiation method and the like to generate oxidation reaction, the product chlorine gas is also excited by light to generate hydrolysis reverse reaction with water, so that the chlorine gas is converted into raw material gas to influence the yield of the product.

Therefore, the application relates to a method for preparing chlorine by hydrogen chloride through photocatalytic oxidation, which adopts the following specific technical scheme: providing a hydrogen chloride-containing gas stream and an oxygen-containing gas stream for oxidizing the hydrogen chloride-containing gas stream into a reactor, reacting hydrogen chloride with oxygen under light irradiation conditions to produce a mixture comprising at least chlorine and water, the reactor being partitioned into a light irradiation zone and a non-light irradiation zone, the light irradiation zone being capable of being irradiated by light and the non-light irradiation zone being incapable of being irradiated by light, gas being communicable between the light irradiation zone and the non-light irradiation zone, the light having a wavelength of any one of or in the range of 150nm to 278 nm.

The inventors have further studied and found that when the energy of light irradiation causes only the activation of HCl without causing the activation of oxygen, the photocatalytic oxidation reaction of hydrogen chloride can not only occur, but also the reaction speed is faster and the yield is higher than when both hydrogen chloride and oxygen are activated. Accordingly, in one embodiment of the present application, the wavelength of the light is any value or range from 240nm to 278 nm.

Further, the water produced by the reaction and chlorine gas are liquefied while hydrogen chloride and oxygen gas are kept in a gaseous state, and liquid chlorine and liquid water are discharged from the reactor. The skilled person will understand how to select a suitable pressure and temperature to liquefy chlorine and water, while the hydrogen chloride and oxygen remain in a gaseous state, and separate the liquid chlorine from the liquid water to obtain chlorine.

In a preferred embodiment of the present application, the water produced by the reaction is liquefied, while the chlorine, hydrogen chloride and oxygen remain in gaseous form, and the liquid water is discharged from the reactor. The skilled person will understand how to select a suitable pressure and temperature to liquefy the water, while the chlorine, hydrogen chloride and oxygen are still in a gaseous state, and separate the chlorine, hydrogen chloride and oxygen to obtain chlorine, which can be recycled in the reactor.

In a particularly preferred embodiment of the present application, a series process flow of n-stage reactors is adopted, each reactor is divided into a light irradiation zone and a no light zone, water in the 1 st to (n-1) th stage reactors is liquefied and discharged from the reactor, chlorine, hydrogen chloride and oxygen are still kept in a gas state, the chlorine in the n-stage reactor is liquefied from the previous stage reactor and enters the next stage reactor, and the hydrogen chloride and the oxygen are still kept in a gas state, wherein n is more than or equal to 2, preferably, n is 3-5.

The hydrogen chloride and the oxygen can enter the reactor again after being discharged from the reactor for recycling, and the implementation mode is more favorable for reducing energy consumption.

The inventors have found that, after the reactor is partitioned into a light irradiation region and a light non-irradiation region, the gas in the light non-irradiation region is not irradiated with light and thus is not photolyzed, so that the photocatalytic back reaction of the product can be reduced.

Preferably, the temperature of the feed gas of hydrogen chloride and oxygen is any value or range of 0-50 ℃. In some preferred aspects of the present invention, the feed gas temperature of hydrogen chloride and oxygen is 0 to 10 ℃, 0 to 20 ℃, 0 to 30 ℃, 0 to 40 ℃, 10 to 20 ℃, 10 to 30 ℃, 10 to 40 ℃, 10 to 50 ℃, 20 to 30 ℃, 20 to 40 ℃, 20 to 50 ℃, 30 to 40 ℃, 30 to 50 ℃ or 40 to 50 ℃.

Preferably, the temperature of the light irradiation region is in any value or range between 0 ℃ and 200 ℃. In some preferred aspects of the present invention, the temperature of the light irradiation region is in the range of 0 to 50 ℃, 0 to 100 ℃, 0 to 150 ℃, 50 to 100 ℃, 50 to 150 ℃, 50 to 200 ℃, 100 to 150 ℃, 100 to 200 ℃ or 150 to 200 ℃, and particularly preferably, the temperature of the light irradiation region is in the range of 20 ℃ to 140 ℃.

Preferably, the hydrogen chloride and the oxygen directly enter the light irradiation region.

The process of the present invention may be carried out continuously or batchwise, preferably continuously.

In all embodiments of the present invention it is preferred that the feed volume ratio of said hydrogen chloride gas containing stream (calculated as pure hydrogen chloride) to said oxygen containing stream for oxidizing the hydrogen chloride gas stream (calculated as pure oxygen) is 4: 1.

The hydrogen chloride-containing gas stream described herein can be a hydrogen chloride-containing gas stream in the form of a by-product from the related industry production, such as the production of isocyanates, the production of acid chlorides, the chlorination of aromatics, and the like. The hydrogen chloride gas containing stream in the form of a by-product may be a hydrogen chloride gas containing stream in the form of a treated by-product or a hydrogen chloride gas containing stream in the form of a by-product directly from the relevant industry without any treatment. The hydrogen chloride-containing gas stream in the form of a byproduct can contain a small amount or no other impurity gases which have no influence on the photocatalytic oxidation of hydrogen chloride and are also derived from related industries according to different sources. The amount of other impurity gases is determined by the nature of the associated industry. Those skilled in the art will appreciate that the so-called off-gas hydrogen chloride produced in the relevant industry may be a suitable feedstock for the present application.

The oxygen-containing gas stream described herein may be pure oxygen or another oxygen-containing gas (e.g., air).

When the water in the reactor is liquefied, a part of hydrogen chloride, chlorine and oxygen enter the condensed water in a small amount and can be separated by a simple distillation method, and the separated gas can be recycled to enter the reactor to continuously participate in the reaction. Similarly, when the water and chlorine gas in the reactor are liquefied, a part of hydrogen chloride and oxygen gas also enter the condensate in small quantity, and can be separated by a simple distillation method, and the separated gas can be recycled into the reactor to continuously participate in the reaction.

The present application relates, in another aspect, to an apparatus for producing chlorine by photocatalytic oxidation of hydrogen chloride, comprising a reactor provided with a gas feed port, a liquid discharge port, and a gas discharge port, the reactor being internally provided with a light source and being partitioned into a light irradiation region and a light-less region by a structure that is gas-permeable and light-impermeable, the light irradiation region being capable of being irradiated with light and the light-less region being incapable of being irradiated with light, the gas between the light irradiation region and the light-less region being capable of flowing.

In a preferred embodiment of the present application, the air-permeable, light-impermeable structure is a louver structure.

In an embodiment of the present application, the structure that is air permeable and light-tight is a double-layer plate structure, and staggered holes are formed in the inner layer plate and the outer layer plate of the double-layer plate, so that the reactor is air permeable and light-tight, and is separated.

In one embodiment of the present application, the air-permeable and light-impermeable structure refers to a structure made of an air-permeable and light-impermeable material, such as an expanded polytetrafluoroethylene film.

Preferably, the liquid discharge port is arranged at the bottom of the reactor, a concave liquid collecting area is arranged at the bottom of the reactor, and the concave liquid collecting area is directly connected with the discharge port. The liquid formed in the reactor is firstly collected in the sunken liquid collecting area and then discharged from the discharge hole.

In a particularly preferred embodiment of the present application, the reactor of the hydrogen chloride photocatalytic oxidation device is a tubular structure and comprises a bent part, one side of the bent part is provided with a light source to form a light irradiation area, and the other side is provided with no light source to form a no light area; preferably, the bending angle of the bent portion is 180 degrees. By utilizing the particularity of the tubular structure, the reactor is divided into a light irradiation area and a no light area without additionally arranging a structure which is permeable to air and not permeable to light.

In a preferred embodiment of the present application, the hydrogen chloride photocatalytic oxidation apparatus, the light irradiation region and the no light region are composed of two separate members connected by a pipe, one of the members is provided with a light source to constitute the light irradiation region, and the other member is provided without a light source to constitute the no light region. The gas between the light irradiation region and the no light region is circulated through the duct. For example, the component provided with the light source is a reactor, and the component without the light source is a cooler, wherein the cooler can be provided as required and is a water cooler or a chiller, or a chiller is further connected behind the water cooler to liquefy the chlorine.

Further, the outer surface of the reactor is provided with a jacket layer. The jacket layer is provided with a heat transfer medium inlet and a heat transfer medium outlet, as will be appreciated by those skilled in the art. It is also possible to provide jackets or other heat exchange devices in the light irradiation region and the non-light-irradiated region, respectively, so as to better control the temperatures of the light irradiation region and the non-light-irradiated region. When the light irradiation area and the non-light irradiation area need to control different temperatures, the structure which is permeable to air and not permeable to light is preferably made of heat insulation materials or is additionally provided with a heat insulation layer. Preferably, the light source is provided in an elongated shape.

Preferably, the gas feed port is provided in the light irradiation region.

The liquid discharge port pipeline is connected with the storage tank.

Preferably, a preheater is arranged on the pipeline where the gas feed inlet is located.

Compared with the prior art, the method has the following beneficial effects:

(1) by dividing the reactor into a special light irradiation area and a no light area, the product gas can be prevented from being continuously photolyzed under the light irradiation condition;

(2) through certain pressure and temperature conditions, partial product gas is directly liquefied and then discharged out of the reactor, so that the reaction balance can be promoted to be carried out towards the direction of generating the product;

(3) the method has mild reaction conditions, uses the photocatalyst, has the advantages of cleanness, environmental protection and the like, and is suitable for industrialization;

(4) the method has the advantages of low investment, easy production capacity and no special requirements on the size and the height-diameter ratio of the reactor.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a hydrogen chloride photocatalytic oxidation apparatus according to example 1 of the present application;

FIG. 2 is a schematic view of the air permeable, light impermeable structural component of FIG. 1;

FIG. 3 is a schematic view showing a hydrogen chloride photocatalytic oxidation apparatus according to example 3 of the present application;

FIG. 4 shows a hydrogen chloride photocatalytic oxidation apparatus according to example 4 of the present application;

FIG. 5 shows a hydrogen chloride photocatalytic oxidation apparatus according to example 6 of the present application;

FIG. 6 shows a hydrogen chloride photocatalytic oxidation apparatus according to example 7 of the present application;

reference signs mean: 1-reactor, 2-light irradiation zone, 3-no light zone, 4-gas permeable and light impermeable structure, 5-gas inlet, 6-liquid outlet, 7-storage tank, 8-jacket, 9-light source, 10-gas outlet, 11-1 st stage reactor, 12-2 nd stage reactor, 13-3 rd stage reactor, 14-4 th stage reactor, 15-water cooler of 4 th stage reactor, 16-deep cooler of 4 th stage reactor, 17-pressure pump, 18-water storage tank, 141-light irradiation zone of 4 th stage reactor.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

Example 1

The apparatus shown in fig. 1 is adopted, comprising a reactor 1, the reactor 1 is provided with a gas inlet 5, a liquid outlet 6 and a gas outlet 10, the reactor 1 is internally provided with a light source, and the interior of the reactor 1 is divided into at least a light irradiation region 2 and a light-free region 3 by a gas-permeable and light-impermeable structure 4, the light irradiation region 2 can be irradiated by light, the light-free region 3 can not be irradiated by light, and gas can flow between the light irradiation region 2 and the light-free region 3. In this embodiment, the air-permeable and light-impermeable structure is a louver structure, a schematic diagram of components of the louver structure is shown in fig. 2, the louver structure is composed of four curved plate bodies, when the louver structure is assembled, adjacent plate bodies are partially overlapped and have gaps, so that light is blocked, and gas can circulate. The liquid discharge port is connected with a storage tank 7 through a pipeline, and the outer surface of the reactor is provided with a jacket layer 8. The light source 9 is strip-shaped and is positioned in the central part of the reactor. The bottom of the reactor is provided with a sunken liquid collecting area which is directly connected with the discharge hole. A pre-cooler (not shown) is arranged on the pipeline where the gas feed inlet is positioned.

The operation process is as follows: continuously supplying a hydrogen chloride gas-containing stream and an oxygen-containing gas stream for oxidising said hydrogen chloride gas-containing stream to the reactor, the gas streams being directed to a light irradiation zone under which conditions the hydrogen chloride reacts with oxygen to form a mixture comprising at least chlorine and water. The gas entering the light-free zone from the light irradiation zone is liquefied at a certain temperature and pressure, particularly chlorine and water which encounter the inner wall of the reactor with relatively low temperature, and flows to the bottom of the reactor along the inner wall of the reactor.

The light irradiation zone is positioned at the central position of the reactor, the interval between the light irradiation zone and the inner wall of the reactor is a no light zone, and heat exchange is carried out through a jacket layer on the outer surface of the reactor.

HCl feed rate 8.8 cubic meters per hour, O₂The feeding rate is 2.2 cubic meters per hour, the temperature of the feeding gas is 5 ℃, the pressure of the reactor is controlled to be 1MPa under the irradiation of a light source with the wavelength of 172nm, the temperature of a light irradiation area of the reactor is 15 ℃, the average temperature of a no light area is controlled to be 8 ℃, hydrogen chloride and oxygen are continuously reacted, the product water and chlorine are continuously liquefied and discharged from the bottom of the reactor, liquid chlorine can be obtained after collection and further treatment, the reaction is carried out for 8 hours in terms of HCl, and the yield of the chlorine is 94.2%.

Example 2

Example 2 the apparatus of example 1 was shown, and the temperature of the light irradiation zone and the temperature of the non-light-irradiated zone were controlled by providing jackets or other heat exchange means in the light irradiation zone and the non-light-irradiated zone, respectively. Wherein, a coil heat exchanger is arranged in the light irradiation area, a jacket is arranged outside the no light area for heat exchange, and the structure which is ventilated and not light-tight in the reactor adopts heat insulation materials. The temperature of the feed gas is 20 ℃, the pressure of the reactor is controlled to be 1MPa, the temperature of the light irradiation zone is controlled to be 60 ℃, and the average temperature of the no light zone is controlled to be 20 ℃. The hydrogen chloride and the oxygen are continuously reacted, the product water and the chlorine are continuously liquefied and discharged from the reactor, and liquid chlorine can be obtained after collection and further treatment, wherein the reaction is carried out for 8 hours in terms of HCl, and the yield of the chlorine is 93.4%.

Example 3

The device shown in figure 3 is adopted, comprising a reactor 1, wherein the reactor 1 is of a tubular structure, the reactor 1 is provided with a gas inlet 5, a liquid outlet 6 and a gas outlet 10, one part of the inside of the reactor 1 is provided with a light source 9, the other part is free of the light source, and the inside of the reactor 1 is divided into a light irradiation area 2 and a no light area 3 by a structure 4 which is permeable and not permeable to light, the light irradiation area 2 can be irradiated by the light, the no light area 3 can not be irradiated by the light, and the gas between the light irradiation area 2 and the no light area 3 can circulate. In this embodiment the ventilative and lighttight structure is the bilayer plate structure, and staggered hole has all been seted up to the inner plate and the outer plywood of bilayer board, and the reactor surface is equipped with jacket layer 8. The light source 9 is arranged in an elongated shape.

In the present embodiment, the jacket layer 8 is provided in each of the light irradiation region 2 and the no-light region 3 so as to control the temperature of the light irradiation region and the temperature of the no-light region. HCl feed rate of 8 cubic meters per hour, O₂The feeding rate is 2 cubic meter/hour, the temperature of the feeding gas is 25 ℃, the pressure of the reactor is controlled to be 1.5MPa, the temperature of a light irradiation area is controlled to be 80 ℃, and the temperature of a no light area is controlled to be 30 ℃ under the irradiation of a light source with the wavelength of 185 nm. The hydrogen chloride and the oxygen are continuously reacted, the product water and the chlorine are continuously liquefied and discharged from the reactor, and liquid chlorine can be obtained after collection and further treatment, wherein the reaction is carried out for 8 hours according to HCl, and the yield of the chlorine is 92.5%.

Example 4

The device shown in figure 4 is adopted, and comprises a reactor 1, wherein the reactor 1 is of a tubular structure and comprisesA bending part is arranged, one side of the bending part is provided with a light source 9, and the other side of the bending part is provided with no light source; the reactor 1 is provided with a gas feed port 5, a liquid discharge port 6 and a gas discharge port 10. In this embodiment, the bending angle of the bending portion is 180 degrees, and a gas-permeable and light-impermeable structure is not required to be additionally provided (as can be understood by those skilled in the art, the reactor is divided into a light irradiation region 2 and a light-free region 3 by at least one bending portion, and the rest portions may also be provided with the bending portion), so that the reactor is divided into the light irradiation region 2 and the light-free region 3, and gas between the light irradiation region 2 and the light-free region 3 can be circulated. The outer surface of the reactor is provided with a jacket layer 8, and the light source 9 is in a strip shape. In the present embodiment, the jacket layer 8 is provided in each of the light irradiation region 2 and the no-light region 3 so as to control the temperature of the light irradiation region and the temperature of the no-light region. HCl feed rate 4 cubic meters per hour, O₂The feeding rate is 1 cubic meter per hour, the temperature of the feeding gas is 30 ℃, the pressure of the reactor is controlled to be 0.5MPa, the temperature of a light irradiation area is controlled to be 140 ℃, and the temperature of a non-light area is controlled to be 4 ℃ under the irradiation of a light source with the wavelength of 172 nm. The hydrogen chloride and the oxygen are continuously reacted, the product water and the chlorine are continuously liquefied and discharged from the reactor, and liquid chlorine can be obtained after collection and further treatment, wherein the reaction is carried out for 8 hours according to HCl, and the yield of the chlorine is 96%.

Example 5

Using the reactor shown in FIG. 1, the HCl feed rate was 4 cubic meters per hour, O₂The feeding rate is 1 cubic meter per hour, the temperature of the feeding gas is 50 ℃, the pressure of the reactor is controlled to be 0.3MPa under the irradiation of a light source with the wavelength of 185nm, the temperature of a light irradiation area of the reactor is controlled to be 95 ℃, and the average temperature of a no light area is controlled to be 75 ℃. And continuously liquefying the product water and discharging the product water from the reactor, maintaining the chlorine, the hydrogen chloride and the oxygen in a gas state, collecting the gas discharged from a gas outlet and further processing the gas to obtain the chlorine, wherein the chlorine is obtained after the reaction is carried out for 8 hours according to HCl, and the yield of the chlorine is 90.8 percent.

Example 6

As shown in FIG. 5, in the 4-stage reactor series process, the 1 st stage reactor 11, the 2 nd stage reactor 12 and the 3 rd stage reactor 13 are internally divided into a light irradiation zone and a no light zone, and the 1 st stage reaction is carried outVessel feed, HCl feed rate 4 cubic meters per hour, O₂The feeding speed is 1 cubic meter/hour, the temperature of the feeding gas is 25 ℃, the wavelength of a light source is 172nm, the pressure of the reactors from 1 st to 3 rd is controlled to be 0.1MPa, the temperature of the light irradiation area of the reactors from 1 st to 3 rd is controlled to be 70 ℃, the average temperature of the no light area of the reactors from 1 st to 3 rd is controlled to be 50 ℃, so that the water in the reactors from 1 st to 3 rd is liquefied and discharged from the reactors and enters a water storage tank 18, while the chlorine, the hydrogen chloride and the oxygen still keep a gas state and enter a 4 th reactor 14 through a pressure pump 17, and the pressure of the reactor from 4 th is controlled to be 0.5 MPa.

In this embodiment, the light irradiation region and the light-free region of the 4 th-stage reactor 14 are composed of two independent parts connected by pipes, one part is a reactor in which a light source is disposed, the whole reactor constitutes the light irradiation region 141 of the 4 th-stage reactor, the other part is composed of a water cooler 15 and a chiller 16, and constitutes the light-free region of the 4 th-stage reactor, and the light irradiation region 141 of the 4 th-stage reactor is connected with the water cooler 15 and the chiller 16 by pipes.

Controlling the temperature of a light irradiation area of a 4 th-stage reactor to be 140 ℃, firstly, cooling gas discharged from the light irradiation area 141 of the 4 th-stage reactor to about 50 ℃ through a water cooler 15, then, cooling the gas in a deep cooler 16 to 4 ℃, wherein the water cooler and the deep cooler are not irradiated with light, water and chlorine are liquefied and discharged from the deep cooler, liquid chlorine is obtained after collection and further treatment, and the chlorine yield is 96.9 percent after the reaction is carried out for 8 hours by HCl; and gas discharged from the deep cooler is recycled into the first-stage reactor.

Example 7

As shown in FIG. 6, a series process flow of 4 stages of reactors (wherein the 1 st to 3 rd stages of the process flow employ the reactor shown in FIG. 1 and the 4 th stage employs the reactor shown in FIG. 3) is employed, and each stage of the reactors is divided into a light irradiation zone and a light non-irradiation zone.

HCl feed rate 4 cubic meters per hour, O₂The feeding speed is 1 cubic meter/hour, the temperature of the feeding gas is 40 ℃, the pressure of the first reactor is controlled to be 0.1MPa, the temperature of a light irradiation zone of the first reactor is controlled to be 60 ℃, the average temperature of a no light zone is 50 ℃, and a light sourceThe wavelength is 220nm, the pressure of the second reactor is controlled to be 0.2MPa, the temperature of a light irradiation area of the second reactor is controlled to be 70 ℃, the average temperature of a light-free area is 65 ℃, the wavelength of a light source is 200nm, the pressure of the third reactor is controlled to be 0.3MPa, the temperature of a light irradiation area of the third reactor is controlled to be 75 ℃, the average temperature of the light-free area is 65 ℃, the wavelength of the light source is 185nm, product water is continuously liquefied and discharged from a 1-stage reactor to a 3-stage reactor, chlorine, hydrogen chloride and oxygen keep a gas state, the chlorine, the hydrogen chloride and the oxygen enter the 2-stage reactor from the 1-stage reactor through a pressure pump 17, then enter the 3-stage reactor from the 2-stage reactor through the pressure pump 17, and finally enter the 4; controlling the pressure of a 4 th-stage reactor to be 0.5MPa, the wavelength of a light source to be 172nm, the temperature of a light irradiation area to be 80 ℃, the temperature of a no light area to be 4 ℃, continuously reacting hydrogen chloride and oxygen, liquefying product water and chlorine, discharging the product water and the chlorine from the 4 th-stage reactor, collecting and further processing the product water and the chlorine to obtain liquid chlorine, wherein the reaction time is 8 hours in terms of HCl, and the yield of the chlorine is 97.2%; the gas discharged from the 4 th-stage reactor is recycled into the first-stage reactor.

Example 8

The apparatus and reaction conditions of example 8 were the same as those of example 2 except that the light source wavelength was 254nm, and the temperatures of the light irradiation region and the non-light-irradiated region were controlled by providing jackets or other heat exchange means in the light irradiation region and the non-light-irradiated region, respectively. Wherein, a coil heat exchanger is arranged in the light irradiation area, a jacket is arranged outside the no light area for heat exchange, and the structure which is ventilated and not light-tight in the reactor adopts heat insulation materials. The temperature of the feed gas is 20 ℃, the pressure of the reactor is controlled to be 1MPa, the temperature of the light irradiation zone is controlled to be 60 ℃, and the average temperature of the no light zone is controlled to be 20 ℃. The hydrogen chloride and the oxygen are continuously reacted, the product water and the chlorine are continuously liquefied and discharged from the reactor, and liquid chlorine can be obtained after collection and further treatment, wherein the reaction is carried out for 8 hours in terms of HCl, and the yield of the chlorine is 95.3%.

Example 9

The apparatus and reaction conditions of example 9 were the same as those of example 5 except that the light source wavelength was 254nm, the HCl feed rate was 4 cubic meters per hour, and O was used₂Feed rate of 1 cubic meter per hour, feed gas temperatureThe temperature is 50 ℃, the pressure of the reactor is controlled to be 0.3MPa, the temperature of a light irradiation area of the reactor is controlled to be 95 ℃, and the average temperature of a no light area is controlled to be 75 ℃. And continuously liquefying the product water and discharging the product water from the reactor, maintaining chlorine, hydrogen chloride and oxygen in a gas state, collecting the gas discharged from a gas outlet and further treating to obtain the chlorine, wherein the chlorine is obtained after the gas is reacted for 8 hours in terms of HCl, and the yield of the chlorine is 93.7 percent.

Comparative example 1

The reactor and process parameters of this example are the same as example 1 except that the reactor was not partitioned with a gas-permeable and light-impermeable structure. The reaction was carried out for 8 hours in terms of HCl, giving a chlorine yield of 61.7%.

Comparative example 2

The reactor and process parameters of this example are the same as example 2 except that the reactor was not partitioned with a gas permeable and light impermeable structure. The reaction was carried out for 8 hours in terms of HCl, giving a chlorine yield of 55.2%.

Comparative example 3

The reactor and process parameters of this example are the same as example 3 except that the reactor was not partitioned with a gas permeable and light impermeable structure. The reaction was carried out for 8 hours in terms of HCl, giving a chlorine yield of 68.6%.

Comparative example 4

The reactor and process parameters of this example are the same as example 8 except that the reactor was not partitioned with a gas-permeable and light-impermeable structure. The reaction was carried out for 8 hours in terms of HCl, giving a chlorine yield of 63.3%.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. A method for preparing chlorine through photocatalytic oxidation of hydrogen chloride is characterized in that a hydrogen chloride gas-containing material flow and an oxygen-containing gas flow for oxidizing the hydrogen chloride gas-containing material flow are provided into a reactor, hydrogen chloride and oxygen react under the irradiation condition to generate a mixture at least containing chlorine and water, the interior of the reactor is divided into a light irradiation area and a non-light irradiation area, the light irradiation area can be irradiated by light, the non-light irradiation area can not be irradiated by light, gas can flow between the light irradiation area and the non-light irradiation area, and the wavelength of the light is 254 nm-278 nm.

2. The process for preparing chlorine by photocatalytic oxidation of hydrogen chloride as claimed in claim 1, wherein the water produced by the reaction and chlorine gas are liquefied while the hydrogen chloride and oxygen gas are kept in a gaseous state, and liquid chlorine and liquid water are discharged from the reactor.

3. The process for preparing chlorine by photocatalytic oxidation of hydrogen chloride as claimed in claim 1, wherein the water produced by the reaction is liquefied while the chlorine, hydrogen chloride and oxygen are kept in a gaseous state, and the liquid water is discharged from the reactor.

4. The method for preparing chlorine through photocatalytic oxidation of hydrogen chloride as recited in claim 1, wherein a series process of n-stage reactors is employed, each of the n-stage reactors is divided into a light irradiation zone and a light-free zone, water in the 1 st to (n-1) th stage reactors is liquefied and discharged from the reactors, while chlorine, hydrogen chloride and oxygen are still in a gaseous state, and the chlorine, hydrogen chloride and oxygen are sequentially introduced from the previous stage reactor into the next stage reactor, so that chlorine in the n-stage reactor is liquefied while hydrogen chloride and oxygen are still in a gaseous state, wherein n is greater than or equal to 2.

5. The method for preparing chlorine through photocatalytic oxidation of hydrogen chloride according to claim 1, wherein a series process flow of n-stage reactors is adopted, each stage reactor is divided into a light irradiation zone and a no light zone, water in the 1 st to (n-1) th stage reactors is liquefied and discharged from the reactors, chlorine, hydrogen chloride and oxygen are kept in a gas state, and the chlorine, the hydrogen chloride and the oxygen are sequentially fed into the next stage reactor from the previous stage reactor, so that the chlorine in the n-stage reactor is liquefied, the hydrogen chloride and the oxygen are kept in the gas state, and n is 3-5.

6. The process for preparing chlorine by photocatalytic oxidation of hydrogen chloride according to claim 1, wherein the feed gas temperature of hydrogen chloride and oxygen is 0 to 50 ℃.

7. The process for preparing chlorine by photocatalytic oxidation of hydrogen chloride according to claim 1, wherein the feed gas temperature of hydrogen chloride and oxygen is 20 to 30 ℃.

8. The method for preparing chlorine through photocatalytic oxidation of hydrogen chloride according to claim 1, wherein the temperature of the light irradiation zone is in the range of 0 ℃ to 200 ℃.

9. The method for preparing chlorine through photocatalytic oxidation of hydrogen chloride according to claim 1, wherein the temperature of the light irradiation zone is in the range of 20 ℃ to 140 ℃.

10. The process for preparing chlorine by photocatalytic oxidation of hydrogen chloride according to claim 1, wherein the feed gas is introduced directly into the light irradiation zone.