Process for the synthesis of vinyl chloride with reduced loss of gold-based catalyst

Abstract

The application belongs to the field of vinyl chloride synthesis process, and particularly relates to a vinyl chloride synthesis process device capable of reducing the loss of gold-based catalysts. The device comprises a converter A, a converter B, a raw material gas pipeline, a front-back station interconnection pipeline and a crude vinyl chloride pipeline; a first valve is arranged between the raw material gas pipeline and the converter A, a second valve is arranged between the front-back station interconnection pipeline and the converter A, a fourth valve is arranged between the crude vinyl chloride pipeline and the bottom of the converter A, a third valve is arranged between the bottom of the converter A and the front-back station interconnection pipeline, a fifth valve is arranged between the raw material gas pipeline and the upper part of the converter B, a sixth valve is arranged between the front-back station interconnection pipeline and the converter B, an eighth valve is arranged between the bottom of the converter B and the crude vinyl chloride pipeline, and a seventh valve is arranged between the bottom of the converter B and the front-back station interconnection pipeline. The application can reduce the loss of gold components in the production process, improve the recovery rate of gold-based catalysts, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of vinyl chloride synthesis process, and particularly relates to a vinyl chloride synthesis process device capable of reducing the loss of gold-based catalyst. BACKGROUND

[0002] Polyvinyl chloride (PVC) resin is a thermoplastic polymer polymerized from vinyl chloride monomer (VCM), and has the characteristics of flame retardation, wear resistance, biodegradation resistance, chemical corrosion resistance, excellent insulation and thermal insulation performance, and the like, and is thus widely used in the manufacture of agricultural films, artificial leather, electrical cables, pearlescent products, various pipes, building materials and the like.

[0003] At present, most of the domestic and foreign PVC production enterprises mainly use calcium carbide acetylene process for production. Since China is rich in coal resources and relatively poor in oil and natural gas resources, most of the domestic PVC production enterprises use calcium carbide acetylene method. The calcium carbide acetylene method PVC reaction mainly uses two-stage fixed bed reactors in series, and HCL and acetylene raw gas sequentially enters the two-stage reactors to react to obtain crude VCM, and the crude VCM is subjected to rectification and monomer polymerization to obtain PVC. The biggest defect of the acetylene method is the use of a highly toxic catalyst system for the core reaction, acetylene hydrochlorination. With the rising global call for mercury ban and the scarcity of mercury resources, the acetylene process is facing the problem of mercury deficiency.

[0004] Gold-based catalyst is the only mercury-free catalyst that has been industrially verified to be feasible, but gold catalyst has the problem of high cost, and it is necessary to reduce the loss of gold catalyst in the use process as much as possible from the aspects of catalyst design, process optimization and production control, so as to optimize the use cost and promote its further industrial application. There are some works published in controlling the loss of gold catalyst. Chinese patent CN202111416151 discloses an acetylene hydrochlorination gold-based catalyst and a preparation method thereof, which inhibits the reduction of high-valence gold species and reduces the loss of gold species by adding a suitable ligand in the catalyst, thereby improving the stability and catalytic activity of the catalyst. Chinese patent CN202111195003 discloses a method for extracting precious metals from waste precious metal catalysts, which improves the recovery rate of precious metals and reduces the energy consumption of the precious metal recovery process by changing the leaching solvent and stepwise dissolution leaching method.

[0005] The technical scheme improves the catalyst design and the leaching method of the recovery process, and improves the gold purity and gold recovery rate of the gold-based catalyst. However, in the production practice, the inventor finds that the acetylene method PVC reaction process is generally composed of two fixed bed reactors in series, the fresh catalyst is loaded into the rear reactor, and after a period of use, the catalyst is unloaded from the rear reactor, turned over to the front reactor for continuous use, and unloaded until the catalyst is completely deactivated. In this way, the catalyst can be fully utilized, and the service life of the catalyst can be prolonged. However, the catalyst is prone to wear and tear and spilling during loading and unloading, resulting in catalyst loss, which in turn reduces the gold recovery rate during the recovery of the waste catalyst. In addition, during the production operation stage, the volatilization of the active component gold due to the pulverization of the catalyst is also an important reason for the reduction of the gold recovery.

[0006] Therefore, how to solve the above-mentioned gold loss problem from the process point of view is the key to improving the gold recovery rate and reducing the use cost of the gold catalyst at the present stage. SUMMARY

[0007] In view of the shortcomings of the prior art, in order to reduce the catalyst loss caused by the wear and tear of the catalyst during the turning process and the volatilization of the gold component during the operation of the catalyst, the application provides a process device for synthesizing chloroethylene by reducing the loss of gold-based catalyst.

[0008] In order to achieve the object of the application, the technical scheme adopted is as follows:

[0009] A process device for synthesizing chloroethylene by reducing the loss of gold-based catalyst, characterized in that the device comprises a converter A, a converter B, a raw material gas pipeline, a front-rear stage communication pipeline and a crude chloroethylene pipeline; a pipeline is connected between the raw material gas pipeline and the converter A, and a first valve is arranged; a pipeline is connected between the front-rear stage communication pipeline and the converter A, and a second valve is arranged; a pipeline is connected between the crude chloroethylene pipeline and the bottom of the converter A, and a fourth valve is arranged; a pipeline is connected between the bottom of the converter A and the front-rear stage communication pipeline, and a third valve is arranged; a pipeline is connected between the raw material gas pipeline and the upper part of the converter B, and a fifth valve is arranged; a pipeline is connected between the front-rear stage communication pipeline and the converter B, and a sixth valve is arranged; a pipeline is connected between the bottom of the converter B and the crude chloroethylene pipeline, and an eighth valve is arranged; a pipeline is connected between the bottom of the converter B and the front-rear stage communication pipeline, and a seventh valve is arranged.

[0010] Preferably, the converter A and the converter B are both tubular fixed bed reactors.

[0011] Preferably, the heat exchange medium in the converter A and the converter B is selected from one of hot water, heptane, octane, and a heptane / octane mixture.

[0012] Preferably, the first and second valves regulate the raw material gas or the outlet gas of the converter B into the converter A, the fifth and sixth valves regulate the raw material gas or the outlet gas of the converter A into the converter B, the third and fourth valves regulate the outlet of the converter A into the converter B or into the subsequent section of the crude vinyl chloride pipeline, and the seventh and eighth valves regulate the outlet of the converter B into the converter A or into the subsequent section of the crude vinyl chloride pipeline.

[0013] Preferably, the converter B is further provided with a gold recovery device, which is filled with activated carbon with a specific surface area of 800-1200 m 2 / g and a wear resistance of 98%. The gold recovery device can be used to recover the adsorbed and pulverized catalyst particles and the volatilized gold components.

[0014] Another object of the present application is to provide a method for reducing the loss of gold-based catalyst, which uses the above process device and comprises the following steps:

[0015] During normal operation, the second, fourth, fifth and seventh valves are closed, and the first, third, sixth and eighth valves are opened, so that the converter A is used as a primary converter and the converter B is used as a secondary converter. When the catalysts in the converter A and the converter B need to be replaced, the waste catalysts in the converter A are replaced with new catalysts, the second, fourth, fifth and seventh valves are opened, and the first, third, sixth and eighth valves are closed, so that the converter B is switched to be used as a primary converter and the converter A is switched to be used as a secondary converter. In this way, the back-end converter can be switched to be used as a front-end converter without disassembling the catalysts, thereby avoiding the loss of catalysts caused by the disassembly and assembly of the catalysts when the catalysts are transferred from the back-end to the front-end.

[0016] Preferably, after the waste catalysts are replaced, the waste catalysts are recovered, and before the recovery, the waste gold-based catalysts are crushed and mixed with an additive to be granulated.

[0017] Preferably, the additive is one or a combination of several of paper pulp, adhesive, lime milk.

[0018] Preferably, the adhesive is selected from one or several of carboxymethylcellulose sodium, polyvinyl acetal, silicate, phosphate and aluminate.

[0019] Preferably, the mass of the additive is 1-10% of the mass of the waste catalysts.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] (1) The present application provides a kind of anti-loss gold-based catalyst synthesis chloroethylene process method, by adding gold recovery device in acetylene method PVC process, recovery of pulverized catalyst particles and volatile gold, reduce the loss of gold catalyst caused by operation process.

[0022] (2) The present application is switched by the combination of the opening and closing of the valve between components, and the first and second converters are switched freely, which reduces the loss of gold component caused by abrasion and pulverization during catalyst loading and unloading.

[0023] (3) The waste gold-based catalyst is pretreated by granulation, and a specific additive is used to make particles of a certain particle size, which improves the combustion efficiency of waste gold catalyst during recovery process, avoids the influence of insufficient combustion on subsequent process, and improves the gold recovery rate of gold-based catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Process device diagram for Example 1;

[0025] Wherein, 1-first valve, 2-second valve, 3-third valve, 4-fourth valve, 5-fifth valve, 6-sixth valve, 7-seventh valve, 8-eighth valve, 9-converter A, 10-converter B, 11-raw material gas pipeline, 12-communication pipeline between front and back stations, 13-rough chloroethylene pipeline.

[0026] Figure 2 Process flow chart for Example 2 method. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with specific embodiments.

[0028] Example 1

[0029] The present application reduces the loss of gold-based catalyst in the process device for synthesizing chloroethylene Figure 1 , the device comprises: converter A 9, converter B 10, raw material gas pipeline 11, communication pipeline between front and back stations 12 and rough chloroethylene pipeline 13;

[0030] The raw material gas pipeline 11 and the converter A 9 are connected by a pipeline and provided with a first valve 1, the front and rear stage communication pipeline 12 and the converter A 9 are connected by a pipeline and provided with a second valve 2, the crude chlorine ethylene pipeline 13 and the bottom of the converter A 9 are connected by a pipeline and provided with a fourth valve 4, the bottom of the converter A 9 and the front and rear stage communication pipeline 12 are connected by a pipeline and provided with a third valve 3, the raw material gas pipeline 11 and the upper part of the converter B 10 are connected by a pipeline and provided with a fifth valve 5, the front and rear stage communication pipeline 12 and the converter B 10 are connected by a pipeline and provided with a sixth valve 6, the bottom of the converter B 10 and the crude chlorine ethylene pipeline 13 are provided with a pipeline and provided with an eighth valve 8, and the bottom of the converter B and the front and rear stage communication pipeline 12 are provided with a pipeline and provided with a seventh valve 7.

[0031] The device is used for synthesizing chlorine ethylene. Figure 1 The method is as follows:

[0032] In normal operation, the second valve 2, the fourth valve 4, the fifth valve 5 and the seventh valve 7 are closed, and the first valve 1, the third valve 3, the sixth valve 6 and the eighth valve 8 are opened, at this time, the converter A 9 is used as a one-stage converter, and the converter B 10 is used as a two-stage converter.

[0033] When the catalysts in the converter A 9 and the converter B 10 are replaced, the waste catalyst in the converter A 9 is replaced with a new catalyst, the second valve 2, the fourth valve 4, the fifth valve 5 and the seventh valve 7 are opened, the first valve 1, the third valve 3, the sixth valve 6 and the eighth valve 8 are closed, the converter B 10 is switched to a one-stage converter, and the converter A 9 is switched to a two-stage converter for use. The rear-stage converter is switched to the front-stage use without disassembling the catalyst.

[0034] Example 2

[0035] A gold recovery device is arranged behind the converter B 10 in the device of example 1, the gold recovery device is filled with activated carbon, the specific surface area of the activated carbon is 800-1200 m 2 / g, and the wear resistance of the activated carbon is 98%. The process flow for synthesizing chlorine ethylene is shown in Figure 2 .

[0036] Example 3

[0037] The waste gold-based catalyst unloaded from the converter A 9 in the device of example 1 is crushed, mixed with lime milk slurry to form 50-80 mm spherical particles, and then sent to a recovery process for recovering the waste gold-based catalyst.

[0038] Blank group: continue to produce according to the conventional production process (the process when example 1 is normally operated), without switching the front and rear converters, without setting the gold recovery device, and without granulating the waste catalyst before burning.

[0039] Test 1

[0040] The gold-based catalyst loss and recovery of the following process methods were investigated.

[0041] (1) The example 1 device was used alone to produce vinyl chloride, the front and rear converters were switched, the waste catalyst was recovered, and the gold-based catalyst loss was calculated.

[0042] (2) The example 2 device was used alone, i.e., a gold recovery device was set after the example 1 device, and the conventional process was normally operated, the second valve 2, the fourth valve 4, the fifth valve 5, and the seventh valve 7 were closed, the converter A 9 was used as a first-stage converter, the converter B 10 was used as a second-stage converter, the front and rear converters were not switched, vinyl chloride was produced, the waste catalyst was recovered, and the gold-based catalyst loss was calculated.

[0043] (3) The method of example 3 was used alone, i.e., the waste catalyst was crushed and granulated after the catalyst was unloaded, the conventional process was normally operated, the second valve 2, the fourth valve 4, the fifth valve 5, and the seventh valve 7 were closed, the converter A 9 was used as a first-stage converter, the converter B 10 was used as a second-stage converter, the front and rear converters were not switched, a gold recovery device was not set, vinyl chloride was produced, the waste catalyst was recovered, and the gold-based catalyst loss was calculated.

[0044] (4) The method of example 1+2+3 was used to synthesize vinyl chloride, and the gold-based catalyst loss was investigated.

[0045] (5) The gold-based catalyst loss of the blank group process was investigated.

[0046] The results are shown in Table 1 below.

[0047] Table 1

[0048]

[0049] The following conclusions can be drawn by comparing examples 1-4:

[0050] Comparing examples 1-3, it can be found that the three technical solutions can effectively reduce gold loss and improve gold recovery rate. Example 1+2+3 shows that the three technical solutions can be used together to greatly improve the gold recovery rate. The above detailed description is a specific description of one of the feasible embodiments of the present application, and this embodiment is not used to limit the patent scope of the present application. Any equivalent implementation or change that does not deviate from the present application should be included in the scope of the technical solutions of the present application.

Claims

1. A method of reducing the loss of a gold-based catalyst, characterized by, The process device used in the method comprises a converter A (9), a converter B (10), a raw material gas pipeline (11), a front and back stage communication pipeline (12) and a crude chloroethylene pipeline (13); the raw material gas pipeline (11) and the converter A (9) are connected by a pipeline and a first valve (1) is arranged, the front and back stage communication pipeline (12) and the converter A (9) are connected by a pipeline and a second valve (2) is arranged, the crude chloroethylene pipeline (13) and the bottom of the converter A (9) are connected by a pipeline and a fourth valve (4) is arranged, the bottom of the converter A (9) and the front and back stage communication pipeline (12) are connected by a pipeline and a third valve (3) is arranged, the raw material gas pipeline (11) and the upper part of the converter B (10) are connected by a pipeline and a fifth valve (5) is arranged, the front and back stage communication pipeline (12) and the converter B (10) are connected by a pipeline and a sixth valve (6) is arranged, the bottom of the converter B (10) and the crude chloroethylene pipeline (13) are connected by a pipeline and an eighth valve (8) is arranged, and the bottom of the converter B (10) and the front and back stage communication pipeline (12) are connected by a pipeline and a seventh valve (7) is arranged; The method comprises the following steps: During normal operation, the second valve (2), the fourth valve (4), the fifth valve (5) and the seventh valve (7) are closed, and the first valve (1), the third valve (3), the sixth valve (6) and the eighth valve (8) are opened, the converter A (9) is used as a one-stage converter, and the converter B (10) is used as a two-stage converter; when the catalyst in the converter A (9) needs to be replaced, the second valve (2), the fourth valve (4), the fifth valve (5) and the seventh valve (7) are opened, and the first valve (1), the third valve (3), the sixth valve (6) and the eighth valve (8) are closed, the converter B (10) is switched to be used as a one-stage converter, and the converter A (9) is switched to be used as a two-stage converter; After the catalyst is replaced, recovery is carried out, and before the recovery, the waste gold-based catalyst is crushed and mixed with an auxiliary agent to be granulated; The auxiliary agent is one or a combination of several of paper pulp, an adhesive and lime milk.

2. The method of claim 1, wherein, The converter A (9) and the converter B (10) are both tubular fixed-bed reactors.

3. The method of claim 1, wherein, The heat exchange medium in the converter A (9) and the converter B (10) is selected from one of hot water, heptane, octane and a heptane / octane mixture.

4. The method of claim 1, wherein, The first valve (1) and the second valve (2) control the raw material gas or the outlet gas of the converter B (10) to enter the converter A (9), the fifth valve (5) and the sixth valve (6) control the raw material gas or the outlet gas of the converter A (9) to enter the converter B (10), the third valve (3) and the fourth valve (4) control the outlet of the converter A (9) to enter the converter B (10) or a subsequent section of the crude chloroethylene pipeline, and the seventh valve (7) and the eighth valve (8) control the outlet of the converter B (10) to enter the converter A (9) or a subsequent section of the crude chloroethylene pipeline (13).

5. The method of claim 1, wherein, The converter B (10) is further provided with a gold recovery device, which is filled with activated carbon with a specific surface area of 800-1200 m 2 / g and a wear resistance of 98%.

6. The method of claim 1, wherein, The adhesive is selected from one or several of sodium carboxymethyl cellulose, polyvinyl acetal, silicate, phosphate and aluminate.

7. The method of claim 1, wherein, The mass of the auxiliary agent is 1-10% of the mass of the waste catalyst.

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