A platinum complex catalyst, its preparation method and application, and a method for preparing vinyl chloride by acetylene hydrochlorination

Abstract

The present invention relates to the field of catalysts, aiming to address the issues of insufficient stability and catalytic activity in existing catalysts. A platinum complex catalyst is provided, wherein the catalyst carrier comprises activated carbon; the catalyst additive comprises an organic compound containing at least one of N, O, S, and P as a heteroatom; and the active component of the catalyst comprises a platinum precursor. Compared to existing metal catalysts for acetylene hydrochlorination, the active component in the insoluble platinum complex catalyst of the present invention is highly dispersed, less susceptible to loss and aggregation, and simultaneously activates both the acetylene and hydrogen chloride reactants, thereby enhancing the catalytic activity and stability of existing metal catalysts.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and in particular to a platinum complex catalyst, a preparation method and application thereof, and a method for preparing vinyl chloride by acetylene hydrochlorination. Background Art

[0002] Polyvinyl chloride (PVC) is a polymer material produced by the polymerization of vinyl chloride (VCM). It ranks third among polymer materials in global usage and is widely used in industry, agriculture, daily life, and other fields. VCM production methods are mainly divided into the acetylene process and the ethylene process. Due to my country's "rich in coal, poor in oil, and little gas" energy structure, the coal-based acetylene process accounts for a much larger proportion (over 80%) than the oil and gas-based ethylene process. With the rapid development of the national economy, my country's PVC production capacity has been rapidly increasing. Since 2007, my country's PVC production capacity has generally shown an upward trend. According to data from the China Chlor-Alkali Industry Association, China's total polyvinyl chloride (PVC) production capacity reached 27.13 million tons / year in 2021, an increase of 490,000 tons / year from 2020. However, current industrial production still uses HgCl2 / C as an industrial catalyst to catalyze the acetylene hydrochlorination reaction. According to statistics, the production of each ton of PVC consumes 1.02-1.41 kg of catalyst, of which approximately 25% of the HgCl2 component is lost during the production cycle. Based on an estimated catalyst lifespan of 10,000 hours, China currently consumes 8,000 tons of mercuric chloride catalyst coal annually, equivalent to 500 tons of mercury resources. This represents approximately 70% of my country's total mercury consumption and 20% of global mercury demand for VCM production. my country has signed the Minamata Convention on Limiting the Use and Emissions of Mercury, requiring the elimination of production processes using mercury or mercury compounds by 2025. Mercury, a scarce resource and a highly environmentally sensitive heavy metal, is in declining supply, while the calcium carbide-based PVC industry's consumption of mercury resources is increasing. This excessive consumption and reliance on mercury resources presents a significant obstacle to the development of calcium carbide-based PVC. Furthermore, mercury-containing wastes emitted during the production process pose a serious threat to human health and the ecological balance. Reducing mercury consumption and pollution is a pressing task for the PVC industry and a key component in achieving sustainable and healthy growth.

[0003] The dual constraints of the Minamata Convention and the "Dual Carbon Goals" have placed higher demands on the green and sustainable development of the polyvinyl chloride industry. Therefore, this project addresses this issue by developing highly efficient, green, and economical non-mercury precious metal catalysts. This will lay the foundation for the use of mercury-free catalysts in the VCM production process, embodying distinct national conditions. Currently, the most common method for preparing supported catalysts in acetylene hydrochlorination is to impregnate a metal precursor and additive onto a support under certain conditions.

[0004] Patent publication number CN116408151A discloses a noble metal catalyst for acetylene hydrochlorination, its preparation method, and application. The catalyst comprises activated carbon, an ionic liquid, and a ruthenium species. The ionic liquid is one or more of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium diimmonium salt, 1-butyl-3-methylimidazolium dicyanoammonium salt, 1-butyl-3-methylimidazolium bromide, N-ethylpyridinium bromide, tributylmethylammonium diimmonium salt, tributylhexylphosphonium bromide, N-butyl-N-methylpyrrolidino bromide, and N-butyl-N-methylpiperidinium bromide. The ionic liquid improves catalyst stability.

[0005] Patent publication number CN113649057A discloses a platinum catalyst for acetylene hydrochlorination to vinyl chloride, its preparation method, and its application. The catalyst's support is carbon nitride, and the active component is platinum, which is present in ionic form on the support. This catalyst, when used in acetylene hydrochlorination processes, can achieve higher vinyl chloride yields. Compared to mercury-free catalysts currently reported in the literature, the catalyst provided by this invention exhibits superior stability and a long service life. Summary of the Invention

[0006] The purpose of the present invention is to provide a platinum complex catalyst and a preparation method thereof, so as to solve the problem that the stability and catalytic activity of existing catalysts are not high enough.

[0007] The embodiments of the present invention are achieved through the following technical solutions:

[0008] A platinum complex catalyst, wherein the catalyst carrier comprises activated carbon; the catalyst promoter comprises an organic matter containing at least one atom of N, O, S and P as a heteroatom; and the active component of the catalyst comprises a platinum precursor.

[0009] Furthermore, the auxiliary agent includes at least one of phenylphosphonyl dichloride, nitrosobenzene, methylphenyl sulfoxide, acetophenone and p-pentylacetophenone. Preferably, the auxiliary agent is nitrosobenzene.

[0010] Furthermore, the platinum precursor includes at least PtCl4, H2PtCl6, (NH4)2PtCl6, and C8H 12 Preferably, the platinum precursor is H2PtCl6.

[0011] Furthermore, based on the total weight of the catalyst, the loading amount of Pt is 0.1-1 wt%, preferably 0.3-0.5 wt%.

[0012] The total weight of the catalyst is calculated as follows: m 总 =m 载体 +m 稳定态金属前驱体 +m助剂 .

[0013] For example: In Example 1, the load is calculated as follows: m Pt / (m 载体 +m 稳定态金属前驱体 +m 助剂 )=0.02g / (0.0421g+0.0110g+9.9469g)=0.2wt%.

[0014] A preparation method of the platinum complex catalyst comprises the following steps: slowly dropping an auxiliary agent solution into a prepared platinum precursor solution for mixing reaction, then adding a carrier into the mixed solution, and finally obtaining the platinum complex catalyst by impregnation and drying.

[0015] Furthermore, the molar ratio of the platinum precursor to the auxiliary agent is 1:0.1-5.

[0016] Furthermore, the molar ratio of the platinum precursor to the auxiliary agent is 1:0.5-2.

[0017] Furthermore, the immersion temperature is 25-150°C and the immersion time is 2-24 hours. Preferably, the immersion temperature is 50-80°C and the immersion time is 4-12 hours.

[0018] Furthermore, the particle size of the carrier is 1.5-5 mm.

[0019] A method for preparing vinyl chloride by acetylene hydrochlorination comprises the following steps: using acetylene and hydrogen chloride as raw materials, mixing and reacting to obtain vinyl chloride; the reaction is carried out under the catalysis of a platinum complex catalyst.

[0020] The reaction is a gas phase reaction.

[0021] The main reactions involved in the acetylene hydrochlorination process include:

[0022] Main reaction: C2H2+HCl→CH2=CHCl

[0023] Non-polymerization side reactions:

[0024] CH2=CHCl+HCl→CH3CHCl2

[0025] CH2=CHCl+HCl→CH2ClCH2Cl

[0026] Polymerization side reactions:

[0027] 2CH2=CHCl→CH2ClCH=CCl-CH3

[0028] 2C2H2→CH2=CH-C≡CH

[0029] Existing thermodynamic studies have shown that the above-mentioned main reaction is significantly affected by polymerization side reactions, while non-polymerization side reactions have little effect on the main reaction. Both the main and side reactions are exothermic, but the thermal effect of the polymerization side reaction is greater than that of the main reaction. Higher temperatures are more conducive to inhibiting the polymerization side reaction, reducing the deposition of polymerization products on the catalyst surface, improving the selectivity of the main reaction, and reducing carbon deposition. However, metal catalysts are subject to valence deactivation at high temperatures. After comprehensively considering the effects of temperature on polymerization side reactions and catalyst reductive deactivation, the reaction temperature is controlled at 110-300°C, more preferably, the reaction temperature is controlled at 140-280°C, and most preferably, the reaction temperature is controlled at 170-240°C.

[0030] The volume ratio of acetylene to hydrogen chloride adopts a commonly used volume ratio in the art, specifically 1:1-2, more preferably, the volume ratio of acetylene to hydrogen chloride is 1:1-1.5, most preferably, the volume ratio of acetylene to hydrogen chloride is 1:1.02-1.2.

[0031] The gas phase reaction is carried out in a fixed bed reactor, and the catalyst is loaded in the fixed bed reactor. The acetylene volume space velocity control range adopts the control range commonly used in this field, specifically 30-1000h -1 Preferably, the acetylene volume space velocity is controlled at 30-360h -1 .

[0032] The platinum complex catalyst is used in the preparation of vinyl chloride by the mixed reaction of acetylene and hydrogen chloride. The reaction is a gas phase reaction at a reaction temperature of 110-300°C.

[0033] The present invention has at least the following beneficial effects:

[0034] Compared with existing metal catalysts for acetylene hydrochlorination, the active components in the insoluble platinum complex catalyst of the present invention are highly dispersed and not easily lost or agglomerated. In addition, the catalyst activates acetylene and hydrogen chloride reactants at the same time, thereby improving the catalytic activity and stability of existing metal catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 1 is a graph showing the relationship between acetylene conversion and reaction time for the catalysts prepared in Examples 1-5 and Comparative Example 1.

[0037] Figure 2The TPD curves of the catalysts prepared in Examples 1-5 and Comparative Example 1 for the reactant acetylene are shown.

[0038] Figure 3 The TPD curves of the catalysts prepared in Examples 1-5 and Comparative Example 1 for the reaction product vinyl chloride are shown.

[0039] Figure 4 The acetylene conversion curves when the catalysts prepared in Examples 6-8 and Example 1 are used in the acetylene hydrochlorination reaction. DETAILED DESCRIPTION

[0040] In order to make the purpose, method scheme and advantages of the embodiments of the present invention clearer, the method scheme in the embodiments of the present invention is clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0041] 1. Preparation method of catalyst:

[0042] Three preparation methods are available, depending on the order in which the carrier, additive, and active ingredient are added. The preferred method is as follows: First, slowly dropwise add the additive solution to the prepared platinum precursor ethanol solution and stir at room temperature for 2-10 hours. Then, add the activated carbon carrier to the mixture and continue stirring for 2-10 hours. After the mixture is allowed to stand at 70°C for 6-12 hours, it is dried at 120°C for 12 hours to obtain the platinum complex catalyst.

[0043] The above limitations on temperature or time are because the insoluble complex needs to be more evenly dispersed on the carrier after reacting at the above temperature for a period of time.

[0044] 2. Acetylene Hydrochlorination

[0045] The platinum complex catalyst prepared in step 1 is loaded into a fixed bed reactor as a catalyst, and acetylene and hydrogen chloride reaction gases are introduced at 110-300°C and an acetylene space velocity (GHSV) of 30-1000h -1 , under the reaction conditions that the volume ratio of acetylene to hydrogen chloride is 1:1-2, the reaction is carried out for 24 hours.

[0046] The reaction temperature is controlled at 110-300°C, more preferably, the reaction temperature is controlled at 140-280°C, and most preferably, the reaction temperature is controlled at 170-240°C.

[0047] Example 1:

[0048] The preparation method of the platinum complex catalyst is as follows:

[0049] In a 50mL beaker, 0.0421g of H2PtCl6 was dissolved in 15mL of ethanol. 15mL of the prepared ethanolic solution of nitrosobenzene (0.0110g) was slowly added dropwise. After stirring for 2 hours, 9.9469g of CAC (1.5mm particle size) was added and stirred for 2 hours. The beaker was sealed with plastic wrap and allowed to stand at 60°C for 6 hours. The solvent was then slowly dried by puncturing the beaker and then dried at 120°C for 12 hours. The resulting catalyst was named Pt-L1 / CAC.

[0050] Example 2:

[0051] The preparation method of the platinum complex catalyst is as follows:

[0052] In a 50mL beaker, 0.0421g of H2PtCl6 was dissolved in 15mL of ethanol. 15mL of the prepared ethanolic solution of phenylphosphonic dichloride (0.0200g) was slowly added dropwise. After stirring for 2 hours, 9.9379g of CAC (1.5mm particle size) was added and stirred for 2 hours. The beaker was sealed with plastic wrap and allowed to stand at 60°C for 6 hours. The solvent was then slowly dried by puncturing the beaker and then dried at 120°C for 12 hours. The resulting catalyst was named Pt-L2 / CAC.

[0053] Example 3:

[0054] The preparation method of the platinum complex catalyst is as follows:

[0055] In a 50mL beaker, 0.0421g of H2PtCl6 was dissolved in 15mL of ethanol. 15mL of the prepared ethanolic solution of methylphenyl sulfoxide (0.0144g) was slowly added dropwise. After stirring for 2 hours, 9.9435g of CAC (1.5mm particle size) was added and stirred for 2 hours. The beaker was sealed with plastic wrap and allowed to stand at 60°C for 6 hours. The solvent was then slowly dried by puncturing the beaker and then dried at 120°C for 12 hours. The resulting catalyst was named Pt-L3 / CAC.

[0056] Example 4:

[0057] The preparation method of the platinum complex catalyst is as follows:

[0058] In a 50mL beaker, 0.0421g of H2PtCl6 was dissolved in 15mL of ethanol. 15mL of the prepared ethanolic solution of acetophenone (0.0123g) was slowly added dropwise. After stirring for 2 hours, 9.9456g of CAC (1.5mm particle size) was added and stirred for 2 hours. The beaker was sealed with plastic wrap and allowed to stand at 60°C for 6 hours. The solvent was then slowly dried by puncturing the beaker and then dried at 120°C for 12 hours. The resulting catalyst was named Pt-L4 / CAC.

[0059] Example 5:

[0060] The preparation method of the platinum complex catalyst is as follows:

[0061] In a 50mL beaker, 0.0421g of H2PtCl6 was dissolved in 15mL of ethanol. 15mL of the prepared ethanol solution of p-pentylacetophenone (0.0195g) was slowly added dropwise. After stirring for 2 hours, 9.9384g of CAC (1.5mm particle size) was added and stirred for 2 hours. The beaker was sealed with plastic wrap and allowed to stand at 60°C for 6 hours. The solvent was then slowly dried by puncturing the beaker and then dried at 120°C for 12 hours. The resulting catalyst was named Pt-L5 / CAC.

[0062] Example 6:

[0063] The preparation method of the platinum complex catalyst is as follows:

[0064] In a 50mL beaker, 0.0345g of H2PtCl6 was dissolved in 15mL of ethanol. 15mL of the prepared ethanolic solution of nitrosobenzene (0.0110g) was slowly added dropwise. After stirring for 2 hours, 9.9545g of CAC (1.5mm particle size) was added and stirred for 2 hours. The beaker was sealed with plastic wrap and allowed to stand at 60°C for 6 hours. The solvent was then slowly dried by puncturing the beaker and then dried at 120°C for 12 hours. The resulting catalyst was named Pt1-L1 / CAC.

[0065] Example 7:

[0066] The preparation method of the platinum complex catalyst is as follows:

[0067] In a 50mL beaker, 0.0455g of (NH4)2PtCl6 was dissolved in 15mL of ethanol. 15mL of the prepared ethanolic solution of nitrosobenzene (0.0110g) was slowly added dropwise. After stirring for 2 hours, 9.9435g of CAC (1.5mm particle size) was added and stirred for 2 hours. The beaker was sealed with plastic wrap and allowed to stand at 60°C for 6 hours. The solvent was then slowly dried by puncturing the beaker and then dried at 120°C for 12 hours. The resulting catalyst was named Pt2-L1 / CAC.

[0068] Example 8:

[0069] The preparation method of the platinum complex catalyst is as follows:

[0070] In a 50 mL beaker, 0.0384 g of C8H 12Cl2Pt was dissolved in 15 mL of ethanol, and 15 mL of a prepared ethanolic solution of nitrosobenzene (0.0110 g) was slowly added dropwise. After stirring for 2 hours, 9.9507 g of CAC (1.5 mm particle size) was added and stirred for 2 hours. The beaker was sealed with plastic wrap and allowed to stand at 60°C for 6 hours. The solvent was then slowly dried by puncturing the beaker, and the mixture was then dried at 120°C for 12 hours. The resulting catalyst was named Pt3-L1 / CAC.

[0071] Comparative Example 1:

[0072] The preparation method of the platinum complex catalyst is as follows:

[0073] In a 50mL beaker, 0.0421g of H2PtCl6 was dissolved in 15mL of ethanol. The prepared 15mL ethanol solution was slowly added dropwise and stirred for 2 hours. Then, 9.9579g of CAC (1.5mm particle size) was added and stirred for 2 hours. The beaker was sealed with plastic wrap and allowed to stand at 60°C for 6 hours. The solvent was then slowly dried by puncturing the beaker, and the mixture was then dried at 120°C for 12 hours. The resulting catalyst was named Pt / CAC.

[0074] Example 9

[0075] 5 mL of the catalyst prepared in Examples 1-5 and Comparative Example 1 were loaded into a fixed bed reactor, and acetylene and hydrogen chloride reaction gases were introduced at 180°C and an acetylene space velocity (GHSV) of 180 h -1 The reaction was carried out under the reaction conditions of a volume ratio of acetylene to hydrogen chloride of 1:1.15 for 24 hours, and the acetylene conversion rate and vinyl chloride selectivity were detected. The test results of the acetylene hydrochlorination reaction catalyzed by each catalyst are shown in Table 1 and Figure 1 .

[0076] Example 10

[0077] 5 mL of the catalysts prepared in Examples 6-8 and Example 1 were respectively loaded into a fixed bed reactor, and acetylene and hydrogen chloride reaction gases were introduced at 180°C and an acetylene space velocity (GHSV) of 180 h -1 The reaction was carried out under the reaction conditions of a volume ratio of acetylene to hydrogen chloride of 1:1.15 for 24 hours, and the acetylene conversion rate and vinyl chloride selectivity were detected. The test results of the acetylene hydrochlorination reaction catalyzed by each catalyst are shown in Table 2 and Figure 4 .

[0078] Table 1 Conversion rate of acetylene hydrochlorination catalyzed by different catalysts

[0079]

[0080]

[0081] Table 2 Conversion rate of acetylene hydrochlorination catalyzed by different precursor catalysts

[0082]

[0083] The catalytic test results of the above catalysts for the acetylene hydrochlorination reaction show that the stability of the catalysts is significantly improved after the addition of the additive. The catalyst containing the nitrogen-oxygen double bond additive also has higher activity and stability than the other additives. The chloroplatinic acid precursor has better reaction performance than the other three precursors.

[0084] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing vinyl chloride by acetylene hydrochlorination, comprising: using acetylene and hydrogen chloride as raw materials, mixing and reacting to obtain vinyl chloride, characterized in that: The reaction is carried out under the catalysis of a platinum complex catalyst; The preparation method of the platinum complex catalyst comprises: slowly adding the auxiliary agent solution dropwise to the prepared platinum precursor solution for mixing reaction, then adding the carrier to the above-mentioned mixed solution, and finally obtaining the platinum complex catalyst by impregnation and drying; the impregnation temperature is 50-150°C; the impregnation time is 6-12 hours; The carrier of the catalyst includes activated carbon; the active component of the catalyst includes a platinum precursor; and the auxiliary agent is nitrosobenzene.

2. The method according to claim 1, characterized in that The platinum precursor includes at least PtCl4, H2PtCl6, (NH4)2PtCl6, and C8H 12 One of Cl2Pt.

3. The method according to claim 2, characterized in that The Pt loading amount is 0.1-1 wt % based on the total weight of the catalyst.

4. The method according to claim 1, wherein The molar ratio of the platinum precursor to the auxiliary agent is 1:0.1-5.

5. The method according to claim 1, wherein The molar ratio of the platinum precursor to the auxiliary agent is 1:0.5-2.

6. The method according to claim 1, wherein The particle size of the carrier is 1.5-5 mm.

Images