A high-catalytic-activity mercury-free catalyst for synthesizing vinyl chloride and a preparation method and application thereof

Abstract

The present application belongs to the technical field of catalysts, and provides a high-catalytic-activity mercury-free catalyst for synthesizing vinyl chloride, a preparation method and application thereof.The high-catalytic-activity mercury-free catalyst for synthesizing vinyl chloride comprises the following components in percentage by mass: 0.03-0.08% of platinum salt, 5-10% of cuprous chloride, 2-5% of bismuth chloride, 3-6% of tin tetrachloride, 1-4% of potassium chloride, and the balance of a porous carrier.The porous carrier in the present application is used for loading active components, and the amount of noble metal platinum is reduced by simultaneously adding cuprous chloride, bismuth chloride, tin tetrachloride and potassium chloride as an additive, while the activity and stability of the mercury-free catalyst are improved.The results of the examples show that the yield of vinyl chloride is 97.9% when the mercury-free catalyst provided by the present application is used for synthesizing vinyl chloride; and the yield of vinyl chloride is 97.2% after 30000h of continuous use.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride, its preparation method, and its application. Background Technology

[0002] Polyvinyl chloride (PVC) resin is an important plastic raw material and one of the five major general-purpose synthetic resins. Vinyl chloride, as a monomer for synthesizing PVC, plays a crucial role in the PVC industry.

[0003] Currently, the main synthesis process for vinyl chloride is the acetylene method, which primarily uses mercuric chloride catalysts. Although mercuric chloride catalysts offer high yields and selectivity, they are accompanied by mercury pollution, making them environmentally unfriendly. Furthermore, China's mercury reserves are limited, and most of the country relies on imports, resulting in high prices for mercuric chloride catalysts and consequently increasing the cost of vinyl chloride production.

[0004] The emergence of mercury-free catalysts has solved the aforementioned problems associated with mercuric chloride-based catalysts. However, most existing mercury-free catalysts use noble metals such as Au and Pd as active centers. Due to the strong reducing properties of acetylene gas in the reaction system, these metal ions with high electrode potentials are reduced by acetylene, resulting in a significant decrease in their activity, which will affect the activity and stability of the mercury-free catalyst. Furthermore, noble metals are relatively expensive, necessitating methods to reduce their loading to lower the cost of mercury-free catalysts. Therefore, how to improve the activity and stability of mercury-free catalysts while reducing the amount of noble metals used has become a pressing technical problem in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride, its preparation method, and its application. The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride provided by this invention has high activity and high stability, and uses a small amount of precious metals.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride, comprising the following components by mass percentage: 0.03-0.08% platinum salt, 5-10% cuprous chloride, 2-5% bismuth chloride, 3-6% tin tetrachloride, 1-4% potassium chloride, and the balance being a porous support.

[0008] Preferably, the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride comprises, by mass percentage: 0.04–0.06% platinum salt, 6–8% cuprous chloride, 3–5% bismuth chloride, 3–5% tin tetrachloride, 2–3% potassium chloride, with the balance being a porous support.

[0009] Preferably, the porous carrier comprises activated carbon or porous silica.

[0010] Preferably, the proportion of micropores in the porous carrier is 75-80%.

[0011] Preferably, the average pore size of the porous carrier is 22–24 nm.

[0012] This invention provides a method for preparing the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride as described in the above technical solution, comprising the following steps:

[0013] (1) The porous carrier is subjected to acid impregnation and washing in sequence to obtain an acid-treated porous carrier;

[0014] (2) Mix platinum salt, cuprous chloride, bismuth chloride, tin tetrachloride and potassium chloride with water to obtain an aqueous solution of the active ingredient;

[0015] (3) The acid-treated porous support obtained in step (1) and the aqueous solution of the active ingredient obtained in step (2) are mixed, and then allowed to stand and dry in sequence to obtain a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride.

[0016] The steps (1) and (2) are not in any particular order.

[0017] Preferably, the mass concentration of the acid used for acid impregnation in step (1) is 5-10%.

[0018] Preferably, the platinum salt in step (2) includes platinum tetrachloride.

[0019] Preferably, in step (3), the volume ratio of the acid-treated porous support to the aqueous solution of the active ingredient is 1:(1-2).

[0020] The present invention also provides the application of the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride described in the above technical solution or the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride prepared by the above preparation method in the synthesis of vinyl chloride.

[0021] This invention provides a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride, comprising the following components by mass percentage: 0.03-0.08% platinum salt, 5-10% cuprous chloride, 2-5% bismuth chloride, 3-6% tin tetrachloride, 1-4% potassium chloride, and the balance being a porous support. The porous support in this invention is used to load the active components. By simultaneously adding cuprous chloride, bismuth chloride, tin tetrachloride, and potassium chloride as auxiliary agents, the amount of precious metal platinum used is reduced, while simultaneously improving the activity and stability of the mercury-free catalyst. Results from the examples show that when the mercury-free catalyst provided by this invention is used to synthesize vinyl chloride, the yield of vinyl chloride is 97.9% and the purity is 98.4%; after continuous use for 30,000 hours, the yield of vinyl chloride is 97.2% and the purity is 97.9%. Detailed Implementation

[0022] This invention provides a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride, comprising the following components by mass percentage: 0.03-0.08% platinum salt, 5-10% cuprous chloride, 2-5% bismuth chloride, 3-6% tin tetrachloride, 1-4% potassium chloride, and the balance being a porous support.

[0023] The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride provided by this invention comprises, by mass percentage, 0.03–0.08% platinum salt, preferably 0.04–0.06%. The platinum salt in this invention serves as the main active component for the catalytic synthesis of vinyl chloride. In this invention, the platinum salt preferably comprises platinum tetrachloride.

[0024] The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride provided by this invention comprises 5-10% cuprous chloride, preferably 6-8%, by mass percentage. The addition of cuprous chloride in this invention improves the stability of the mercury-free catalyst.

[0025] The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride provided by this invention comprises 2-5% bismuth chloride, preferably 3-5%, by mass percentage. The addition of bismuth chloride in this invention improves the conversion rate and selectivity of the mercury-free catalyst, and also contributes to its stability.

[0026] The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride provided by this invention comprises 3-6% tin tetrachloride, preferably 3-5%, by mass percentage. The addition of tin tetrachloride in this invention improves the activity of the mercury-free catalyst.

[0027] The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride provided by this invention comprises, by mass percentage, 1-4% potassium chloride, preferably 2-3%. By adding potassium chloride, this invention significantly improves the stability of the mercury-free catalyst.

[0028] The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride provided by this invention further includes, by weight percentage, a porous support. The porous support in this invention is used to support the active components platinum salt, cuprous chloride, bismuth chloride, tin tetrachloride, and potassium chloride.

[0029] In this invention, the porous support preferably comprises activated carbon or porous silica, more preferably activated carbon. This invention does not impose any particular limitation on the source of the porous support; commercially available products well-known to those skilled in the art can be used.

[0030] In this invention, the proportion of micropores in the porous carrier is preferably 75-80%, more preferably 76-78%. The use of a porous carrier with a micropore proportion within the above range is beneficial for obtaining a highly active mercury-free catalyst.

[0031] In this invention, the average pore size of the porous support is preferably 22-24 nm. This invention preferably uses a porous support with an average pore size within the above range. If the average pore size of the porous support is too small, it is not conducive to the diffusion of reactants and products in the pores, resulting in low acetylene conversion and reduced activity and stability of the mercury-free catalyst. If the average pore size of the porous support is too large, it will reduce the number of active sites, causing a decrease in the activity of the mercury-free catalyst, and will also produce the byproduct dichloroethane.

[0032] The porous carrier in this invention is used to load the active components. By simultaneously adding cuprous chloride, bismuth chloride, tin tetrachloride and potassium chloride as auxiliaries, the amount of precious metal platinum used is reduced, while the activity and stability of the mercury-free catalyst are improved.

[0033] This invention provides a method for preparing the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride as described in the above technical solution, comprising the following steps:

[0034] (1) The porous carrier is subjected to acid impregnation and washing in sequence to obtain an acid-treated porous carrier;

[0035] (2) Mix platinum salt, cuprous chloride, bismuth chloride, tin tetrachloride and potassium chloride with water to obtain an aqueous solution of the active ingredient;

[0036] (3) The acid-treated porous support obtained in step (1) and the aqueous solution of the active ingredient obtained in step (2) are mixed, and then allowed to stand and dry in sequence to obtain a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride.

[0037] The steps (1) and (2) are not in any particular order.

[0038] This invention involves sequentially acid-impregnating and cleaning a porous carrier to obtain an acid-treated porous carrier. The invention removes impurities from the porous carrier through acid impregnation and then removes residual acid from the porous carrier through cleaning.

[0039] This invention does not impose any particular limitation on the acid impregnation operation; any impregnation technique well-known to those skilled in the art can be used. In this invention, the mass concentration of the acid used for acid impregnation is preferably 5-10%, more preferably 6-8%. In this invention, the acid used for acid impregnation is preferably hydrochloric acid. This invention does not impose any particular limitation on the amount of acid used, as long as it is sufficient to completely impregnate the porous carrier. In this invention, the acid impregnation temperature is preferably 35-50°C; the acid impregnation time is preferably 2-3 hours.

[0040] This invention does not impose any special limitations on the cleaning operation; any cleaning technique well-known to those skilled in the art can be used. In this invention, the cleaning reagent is preferably deionized water. In this invention, the cleaning is preferably performed 3 to 4 times.

[0041] This invention involves mixing platinum salt, cuprous chloride, bismuth chloride, tin tetrachloride, and potassium chloride with water to obtain an aqueous solution of the active ingredient. This invention prepares the aqueous solution of the active ingredient by mixing platinum salt, cuprous chloride, bismuth chloride, tin tetrachloride, and potassium chloride with water, so that the active component can be subsequently loaded onto a porous carrier.

[0042] The present invention does not have any special limitations on the operation of mixing the platinum salt, cuprous chloride, bismuth chloride, tin tetrachloride and potassium chloride with water, and solid-liquid mixing methods well known to those skilled in the art can be used.

[0043] In this invention, the platinum salt preferably comprises platinum tetrachloride. This invention does not impose any particular limitation on the source of the platinum tetrachloride; commercially available products well-known to those skilled in the art can be used.

[0044] After obtaining an acid-treated porous support and an aqueous solution of the active ingredient, the present invention mixes the acid-treated porous support and the aqueous solution of the active ingredient, and then allows them to stand and dry in sequence to obtain a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride.

[0045] The present invention does not have any special limitations on the operation of mixing the acid-treated porous carrier and the aqueous solution of the active ingredient; any mixing technique known to those skilled in the art can be used.

[0046] In this invention, the volume ratio of the acid-treated porous support to the aqueous solution of the active ingredient is preferably 1:(1-2), more preferably 1:1. This invention preferably controls the volume ratio of the acid-treated porous support to the aqueous solution of the active ingredient within the above range, which is beneficial for ensuring the adsorption amount of the active component.

[0047] This invention does not impose any special limitations on the settling operation; any settling technique well-known to those skilled in the art can be used. In this invention, the settling temperature is preferably room temperature; the settling time is preferably 2–3 hours. Through settling, this invention allows the active components—platinum salt, cuprous chloride, bismuth chloride, tin tetrachloride, and potassium chloride—to be fully adsorbed onto the porous carrier.

[0048] This invention does not impose any special limitations on the drying operation; any drying technique well-known to those skilled in the art can be used. In this invention, the drying temperature is preferably 150–180°C; the drying time is preferably 0.5–1.5 hours. This invention removes moisture through drying.

[0049] The present invention also provides the application of the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride described in the above technical solution or the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride prepared by the above preparation method in the synthesis of vinyl chloride.

[0050] In this invention, the application of the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride preferably includes the following steps:

[0051] (1) The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride is loaded into each tube of the reactor and the loading is completed within 30 to 60 minutes.

[0052] (2) After the filling in step (1) is completed, dry acetylene and hydrogen chloride gas at 110-120℃ is introduced into the reactor, and the rate is controlled at 5-8m. 3 / h, continuously for 12 to 15 hours, during which acid is released from the bottom of the reactor once every 2 to 2.5 hours;

[0053] (3) A mixture of acetylene and hydrogen chloride in a molar ratio of 1:(0.87-1.07) and preheated to 45-50°C is introduced into the reactor in step (2). The temperature is controlled at 120-130°C and the mixture is incubated for 10-12 days. Then, the amount of acetylene gas introduced is adjusted according to the reactor's cooling capacity so that the molar ratio of acetylene and hydrogen chloride is controlled at 1:(0.87-1.07). The synthesis reaction is carried out at 180-190°C to obtain vinyl chloride.

[0054] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] Example 1

[0056] A highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride comprises, by mass percentage: 0.04% platinum tetrachloride, 6% cuprous chloride, 4% bismuth chloride, 5% tin tetrachloride, 2% potassium chloride, with the balance being activated carbon; the activated carbon contains 76% micropores and has an average pore size of 22 nm.

[0057] Preparation process:

[0058] (1) The activated carbon was first soaked in 6% hydrochloric acid at 40°C for 2 hours, and then washed with deionized water 3 times to obtain acid-treated activated carbon.

[0059] (2) Platinum tetrachloride, cuprous chloride, bismuth chloride, tin tetrachloride and potassium chloride are mixed with water to obtain an aqueous solution of the active ingredients;

[0060] (3) The acid-treated activated carbon obtained in step (1) and the aqueous solution of the active ingredient obtained in step (2) are mixed at a volume ratio of 1:1, and then allowed to stand at room temperature for 2 hours. After that, the mixture is dried at 160°C for 1 hour to obtain a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride.

[0061] Example 2

[0062] A highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride comprises, by mass percentage: 0.03% platinum tetrachloride, 10% cuprous chloride, 4% bismuth chloride, 6% tin tetrachloride, 2% potassium chloride, and the balance being activated carbon; the activated carbon contains 76% micropores and has an average pore size of 22 nm.

[0063] The preparation process is the same as in Example 1.

[0064] Example 3

[0065] A highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride comprises, by mass percentage: 0.06% platinum tetrachloride, 7% cuprous chloride, 3% bismuth chloride, 3% tin tetrachloride, 4% potassium chloride, with the balance being activated carbon; the activated carbon contains 76% micropores and has an average pore size of 22 nm.

[0066] The preparation process is the same as in Example 1.

[0067] Example 4

[0068] A highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride comprises, by mass percentage: 0.08% platinum tetrachloride, 5% cuprous chloride, 3% bismuth chloride, 3% tin tetrachloride, 2% potassium chloride, with the balance being activated carbon; the activated carbon contains 76% micropores and has an average pore size of 22 nm.

[0069] The preparation process is the same as in Example 1.

[0070] Example 5

[0071] A highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride comprises, by mass percentage: 0.08% platinum tetrachloride, 5% cuprous chloride, 3% bismuth chloride, 3% tin tetrachloride, 2% potassium chloride, with the balance being porous silica; the porous silica contains 76% micropores and has an average pore size of 22 nm.

[0072] The preparation process is the same as in Example 1.

[0073] Comparative Example 1

[0074] The difference from Example 1 is that the amount of platinum tetrachloride is 0.01%.

[0075] Comparative Example 2

[0076] The difference from Example 1 is that cuprous chloride is 15%.

[0077] Comparative Example 3

[0078] The difference from Example 1 is that it does not contain potassium chloride.

[0079] Comparative Example 4

[0080] The difference from Example 1 is that it does not contain tin tetrachloride.

[0081] Comparative Example 5

[0082] The difference from Example 1 is that the activated carbon contains 70% micropores.

[0083] Comparative Example 6

[0084] The difference from Example 1 is that the activated carbon contains 85% micropores.

[0085] Comparative Example 7

[0086] The difference from Example 1 is that the average pore size of the activated carbon is 32 nm.

[0087] Comparative Example 8

[0088] The difference from Example 1 is that the average pore size of the activated carbon is 12 nm.

[0089] Application Examples 1-5 and Comparative Application Examples 1-8

[0090] (1) The mercury-free catalysts prepared in Examples 1-5 and Comparative Examples 1-8 were loaded into each tube of the reactor and the loading was completed within 30 minutes.

[0091] (2) After the filling in step (1) is completed, dry acetylene and hydrogen chloride gas at 110°C is introduced into the reactor at a controlled rate of 5m. 3 / h, continuously for 12h, with acid released from the bottom of the reactor once every 2h during the period;

[0092] (3) A mixture of acetylene and hydrogen chloride in a molar ratio of 1:1.07, and preheated to a temperature of 45°C or higher, is introduced into the reactor in step (2). The temperature is controlled at 120°C and the mixture is incubated for 10 days. Then, the amount of acetylene gas introduced is adjusted according to the cooling capacity of the reactor so that the molar ratio of acetylene and hydrogen chloride is controlled at 1:1.07. The synthesis reaction is carried out at 180°C to obtain vinyl chloride.

[0093] (4) The mercury-free catalysts prepared in Examples 1-5 and Comparative Examples 1-8 were used again in the vinyl chloride synthesis reaction after 30,000 hours of continuous use.

[0094] The vinyl chloride prepared by Application Examples 1-5 and Comparative Examples 1-8 was analyzed by chromatography, and its yield and purity were calculated. The results are shown in Table 1.

[0095] Table 1 shows the yield and purity of vinyl chloride in Application Examples 1-5 and Comparative Application Examples 1-8.

[0096]

[0097]

[0098] As can be seen from the above embodiments, the present invention provides a high-activity and high-stability material with low precious metal content. When used to synthesize vinyl chloride, the yield of vinyl chloride is 97.9% and the purity is 98.4%. After continuous use for 30,000 hours, the yield of vinyl chloride is 97.2% and the purity is 97.9%.

[0099] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride, comprising the following components by mass percentage: 0.03-0.08% platinum salt, 5-10% cuprous chloride, 2-5% bismuth chloride, 3-6% tin tetrachloride, 1-4% potassium chloride, with the balance being a porous support; The porous carrier contains 75-80% micropores; The average pore size of the porous carrier is 22~24 nm.

2. The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride according to claim 1, characterized in that, The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride comprises, by mass percentage: 0.04-0.06% platinum salt, 6-8% cuprous chloride, 3-5% bismuth chloride, 3-5% tin tetrachloride, 2-3% potassium chloride, with the balance being a porous support.

3. The highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride according to claim 1 or 2, characterized in that, The porous carrier includes activated carbon or porous silica.

4. The method for preparing the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride according to any one of claims 1 to 3, comprising the following steps: (1) The porous carrier is subjected to acid impregnation and washing in sequence to obtain an acid-treated porous carrier; (2) Mix platinum salt, cuprous chloride, bismuth chloride, tin tetrachloride and potassium chloride with water to obtain an aqueous solution of the active ingredient; (3) The acid-treated porous support obtained in step (1) and the aqueous solution of the active ingredient obtained in step (2) are mixed, and then allowed to stand and dry in sequence to obtain a highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride. The steps (1) and (2) are not in any particular order.

5. The preparation method according to claim 4, characterized in that, The mass concentration of the acid used in step (1) for acid impregnation is 5-10%.

6. The preparation method according to claim 4, characterized in that, The platinum salt in step (2) includes platinum tetrachloride.

7. The preparation method according to claim 4, characterized in that, In step (3), the volume ratio of the acid-treated porous support to the aqueous solution of the active ingredient is 1:(1~2).

8. The application of the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride as described in any one of claims 1 to 3, or the highly catalytically active mercury-free catalyst for the synthesis of vinyl chloride prepared by the preparation method described in any one of claims 4 to 7, in the synthesis of vinyl chloride.

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