A method for preparing a highly dispersed Ru catalyst for the fixed-bed acetylene process to produce vinyl chloride and its application method.

Abstract

This invention discloses a method for preparing and using a highly dispersed Ru catalyst for the fixed-bed acetylene process to prepare vinyl chloride. The method employs a "confined coordination + pyrolysis anchoring" strategy, utilizing the spatial confinement of the ruthenium salt precursor within the polymer three-dimensional network and the coordination effect of the polymer monomers on Ru species to achieve uniform and stable dispersion of the ruthenium salt in the polymer system. Based on this, the aforementioned ruthenium salt-containing polymer system is pyrolyzed at high temperature, causing the Ru species to be anchored in situ onto a carbon substrate by N atoms, achieving stable and highly dispersed active metal Ru. Subsequently, the addition of phosphazene compounds and ionic liquids (especially morpholine-based ionic liquids) as auxiliaries further enhances the valence stability of the Ru species and effectively inhibits the formation of reaction carbon deposits, thereby significantly improving the activity and long-term reaction stability of the Ru catalyst.

Description

Technical Field

[0001] This invention proposes a method for preparing and using a highly dispersed Ru catalyst for the fixed-bed acetylene-to-vinyl chloride process, belonging to the field of chemical catalysis. This method employs a "confined coordination + pyrolysis anchoring" strategy, significantly improving the dispersibility and stability of active Ru species on a carbon support. When applied to the fixed-bed acetylene hydrochlorination reaction, this catalyst exhibits good catalytic activity and stability. Background Technology

[0002] Polyvinyl chloride (PVC), the world's second-largest thermoplastic resin, is a pillar industry for my country's chlor-alkali sector. Vinyl chloride is the monomer for PVC synthesis, and there are two mature synthesis methods: the acetylene process and the ethylene process. Given my country's energy structure—lacking oil and natural gas but rich in coal—and the competitive advantages of the acetylene process (mature technology, low water consumption, and low production costs), the coal-based acetylene process is the mainstream technology for PVC production in my country. Currently, in the core catalytic stage of vinyl chloride synthesis, almost all processes use activated carbon-supported mercuric chloride catalysts. This makes PVC production the largest consumer of mercury in my country, accounting for 60% of China's total mercury consumption and 30% of the world's.

[0003] Given the significant environmental hazards posed by mercury emissions, the United Nations Environment Programme announced a ban on the production of mercury-containing products after 2020, making the de-mercury removal from the PVC industry imperative. Therefore, the development of green and efficient mercury-free catalysts has important theoretical and practical significance.

[0004] Academician Chen Rongti of Nankai University began research on mercury-free catalysts in the 1970s, and his developed stannous chloride catalyst showed good initial activity. Subsequently, Professor Hutchings of Cardiff University discovered a linear relationship between metal electrode potential and the activity of acetylene hydrochlorination, and predicted that Au(III) (E0 = 1.42V), with its higher electrode potential, should have higher activity in the acetylene hydrochlorination reaction. This was verified in his work in 1988, providing a theoretical basis for finding alternative metals to mercury. After years of continuous research, current research on mercury-free catalysts mainly focuses on noble metal catalysts such as Au, Pd, Ru, and Pt with higher electrode potentials. Au-based mercury-free catalysts have been proven to be the closest to replacing Hg catalysts. However, gold is expensive, and researchers are also working to develop other more affordable alternative metals.

[0005] Since the standard electrode potential of Ru(III) is similar to that of Hg(II) (E(Ru) 3+ )=0.455V; E(Hg) 2+With a potential energy level of 0.851 V, Ru metal is considered a very promising active metal. Dai et al. (Can J Chem, 2013, 91:120–125) calculated using DFT that when HgCl2, AuCl3, and RuCl3 are used as the catalytically active components, their reaction barriers are 16.3, 11.9, and 9.1 kcal / mol, respectively, suggesting Ru is a good alternative to Hg and Au. Indeed, numerous studies have shown that Ru metal possesses initial activity data comparable to Au. However, Ru species are prone to reduction and aggregation during catalytic reactions, leading to catalyst deactivation, and carbon deposition is also a major problem for Ru catalysts. Furthermore, the current Ru catalyst loading is relatively high (approximately 1 wt%), far exceeding the 0.1 wt% of Au catalysts. These issues severely limit its industrial application. Some progress has been made in the modification of Ru catalysts. For example, the literature (RSC Adv, 2013, 3:21062–21068) reported single-metal Ru / SAC and second-metal-doped Ru-Cu / SAC and Ru-Co / SAC catalysts. Among them, the catalyst Ru1Co3 / SAC with a Ru loading of 1 wt% showed the best catalytic activity at 170 °C and an acetylene space velocity of 180 h⁻¹. -1 Under certain conditions, over 95% acetylene conversion can be achieved. Although the addition of a second metal improves the catalyst activity to some extent, the catalyst exhibits significant Ru nanoparticle formation, which obviously reduces the utilization rate of the precious metal. Modification with heteroatom supports or modification of Ru sites using alkali metals can improve the activity of Ru catalysts, but deactivation remains a problem over the long term. Literature (ACS Catal, 2017, 7:3510–3520) reports an ionic liquid-modified ruthenium catalyst; the optimal catalyst, 0.2% Ru@15% TPPB / AC, maintains an acetylene conversion rate above 99.3% in a 400-h reaction evaluation, but this catalyst suffers from significant metal loss. Patent application CN202010383081.3 discloses a ruthenium catalyst with ruthenium salt as the active component and propylenediamine as the modifying agent, which can reduce the ruthenium loading to below 1 wt%. Patent application CN201710907314.3 discloses a ruthenium catalyst with ruthenium salt as the active component and ionic liquid and inorganic salt as modifying agents. In the above-disclosed catalysts, a post-supporting method is used to impregnate the active metal onto the support. Although subsequent modification can improve the dispersion of Ru to some extent, characterization results such as transmission electron microscopy indicate that there is still considerable room for improvement in the geometric and spatial distribution of Ru species. Summary of the Invention

[0006] To address the problems encountered by Ru catalysts in the hydrochlorination of acetylene, this invention proposes a "confined coordination + pyrolysis anchoring" strategy. This strategy leverages the spatial confinement of the ruthenium salt precursor within a three-dimensional polymer network and the coordination of Ru species with the polymer monomers to achieve uniform and stable dispersion of the ruthenium salt in the polymer system. Based on this, the aforementioned ruthenium salt-containing polymer system is pyrolyzed at high temperature, resulting in the in-situ anchoring of Ru species to a carbon substrate by N atoms. This achieves stable and highly dispersed active metal Ru. Subsequently, the addition of phosphazene compounds and ionic liquids (especially morpholine-based ionic liquids) as promoters further enhances the valence stability of Ru species and effectively inhibits the formation of reaction carbon deposits, thereby significantly improving the activity and long-term reaction stability of the Ru catalyst. The aforementioned disclosure differs significantly from the catalyst composition, structure, and preparation method proposed in this invention.

[0007] The specific technical solution of the present invention is as follows:

[0008] Option 1: A highly dispersed Ru catalyst for the preparation of vinyl chloride via a fixed-bed acetylene process, characterized in that the catalyst is prepared according to the following steps:

[0009] (1) Add vinylpyridine, vinylimidazolium, acrylonitrile, styrene and divinylbenzene to ethyl acetate and stir until homogeneous to obtain a mixed solution; then add ruthenium salt to the aforementioned mixed solution and reflux at 80–100°C for at least 6 hours to obtain solution A; cool solution A to room temperature naturally, add an azo compound as a polymerization initiator, and stir thoroughly to dissolve to obtain solution B;

[0010] (2) Transfer solution B to a high-pressure reactor with a polytetrafluoroethylene liner. Under stirring, use a gradient heating process. First, heat the mixture from room temperature to 60–65°C at a heating rate of 1–3°C / min to initiate the polymerization reaction. After reacting for 1–2 hours, turn off the stirring and maintain the temperature for 6–8 hours. Then, continue heating the mixture at a heating rate of 5–10°C / min to 100–105°C for aging for at least 6 hours. After that, allow it to cool naturally to room temperature. Take out the block polymer obtained from the reaction and let it dry naturally. After drying, crush the sample to 40–60 mesh for later use.

[0011] (3) The above polymer powder was placed in a high-temperature tube furnace and the sample was heat-treated by the "low-temperature pre-oxidation + high-temperature carbonization" process. First, the sample was pre-oxidized by heating from room temperature to 300–350°C at a heating rate of 1–3°C / min in a flowing air atmosphere for 1–3 h. Then, the air was switched to a flowing non-oxidizing atmosphere and the sample was further carbonized by heating to 600–1000°C at a heating rate of 1–3°C / min for 2–3 h. After the carbonization was completed, the sample was naturally cooled to room temperature to obtain the carbonized sample.

[0012] (4) Dissolve the phosphazene compound and ionic liquid in deionized water or ethanol, and impregnate them into the carbonized sample using an equal-volume impregnation method. Dry the impregnated sample at 80–100°C for 4–6 hours to obtain the Ru-based catalyst.

[0013] Scheme 2, the Ru catalyst as described in Scheme 1, characterized in that: in step (1), the mass ratio of vinylpyridine, vinylimidazolium, acrylonitrile, styrene, divinylbenzene and ethyl acetate is 1.0:0.5–1.0:0.5–2.0:0.5–1.5:0.3–1.5:15.

[0014] Scheme 3, the Ru catalyst as described in Scheme 1, characterized in that: in step (1), the ruthenium salt is one or more of ruthenium acetate, ruthenium acetylacetonate, ruthenium trichloride, ruthenium iodide, ruthenium bromide, dodecyltriruthenium, dichlorophenylruthenium(II) dimer, ammonium hexachlororuthenium, tetralactam perruthenium, dichlorotetra(triphenylphosphine)ruthenium, tris(2,2-bipyridine)ruthenium chloride, tris(triphenylphosphine) dichloride, ethylenedicarbonylruthenium, bis(pentamethylcyclopentadiene)ruthenium, tris(2,2'-bipyridine) dichloride, and (1,5-cyclooctadiene) dichloride, wherein the mass of the ruthenium salt is 0.25%–5% of the sum of the masses of vinylpyridine, vinylimidazole, acrylonitrile, styrene, and divinylbenzene.

[0015] Scheme 4, the Ru catalyst as described in Scheme 1, characterized in that: in step (1), the azo initiator is one or a mixture of azobisisobutyronitrile and azobisisoheptanenitrile, and the mass of the azo compound is 1.5%–4% of the sum of the masses of vinylpyridine, vinylimidazolium, acrylonitrile, styrene and divinylbenzene.

[0016] Option 5: The Ru catalyst as described in Option 1, characterized in that: in step (3), the non-oxidizing atmosphere is one or more of nitrogen, argon, helium, ammonia, and hydrogen; the gas volume hourly space velocity (GHSV) of air or the non-oxidizing atmosphere is 10–40 h⁻¹. –1 .

[0017] Scheme 6: The Ru catalyst as described in Scheme 1, characterized in that: in step (4), the phosphazene compound is one or more of hexachlorotriphosphazene, phenoxycyclophosphazene, hexafluorocyclotriphosphazene, ethoxy(pentafluoro)cyclotriphosphazene, pentafluoro(phenoxy)cyclotriphosphazene, and the phosphazene ligand P1-tert-octyl; the ionic liquid is one or more of imidazole ionic liquids, piperidine ionic liquids, quaternary ammonium salt ionic liquids, quaternary phosphonium salt ionic liquids, pyrrolidine ionic liquids, morpholine ionic liquids, and pyridine ionic liquids. The preferred ionic liquids are morpholine-based, including N-ethyl-methylmorpholine bromide, N-propyl-methylmorpholine bromide, and N-butyl-methylmorpholine bromide. The piperidine-based ionic liquids have N-alkylpyridine as the cation, where the alkyl group includes ethyl, butyl, hexyl, and octyl, and the anion includes chlorine, bromine, tetrafluoroboric acid, hexafluorophosphate, and bis(trifluoromethanesulfonyl)imide. The molar ratio of ruthenium salt to phosphazene compound to ionic liquid is 1.0:0.05–1.0:0.5–1.5.

[0018] Option 7: A method of using the Ru catalyst described in Options 1–6, characterized by the following steps:

[0019] (1) Place the catalyst in a fixed-bed reactor and heat it to 120–220 °C under a flowing nitrogen atmosphere and hold it at that temperature for at least 1 h, wherein the volume hourly space velocity of nitrogen is 15–45 h⁻¹. –1 ;

[0020] (2) Turn off the nitrogen gas and switch to flowing hydrogen chloride gas, and keep it at a constant temperature for at least 1 hour, with a hydrogen chloride volume hourly space velocity of 15–45 h⁻¹. –1 ;

[0021] (3) After adjusting the reactor temperature to 120–240℃, acetylene gas is introduced, with an acetylene volume hourly space velocity of 15–400 h⁻¹. –1 The molar ratio of hydrogen chloride to acetylene is controlled to be 1.05–1.3:1;

[0022] (4) Use gas chromatography to perform quantitative analysis of the gas after the reaction.

[0023] Compared with the prior art, the present invention has the following significant innovations:

[0024] (1) This invention proposes a "confined coordination + pyrolysis anchoring" strategy, which utilizes the spatial confinement of the ruthenium salt precursor by the polymer three-dimensional network and the coordination effect of the polymer monomer on Ru species to achieve uniform and stable dispersion of ruthenium salt in the polymer system. Based on this, the above-mentioned ruthenium salt-containing polymer system is pyrolyzed at high temperature, and Ru species are anchored in situ on the carbon substrate by N atoms, achieving stable and highly dispersed active metal Ru. Compared with conventional post-supported schemes, this catalyst preparation strategy results in more uniform Ru loading and significantly reduces the amount of precious metal used. At the same time, Ru atoms are stably coordinated by N sites on the carbon support surface, effectively suppressing the aggregation and loss behavior of Ru in the reaction and improving the stability of the catalyst.

[0025] (2) In the polymerization stage, we selected a high-pressure reactor as the reaction vessel and initiated explosive polymerization by rapidly heating in a closed environment at 60–65℃, thus preparing a high-density polymer material containing a three-dimensional cross-linked network in a short time. This material can not only disperse noble metal salt precursors in situ through physical barriers and chemical coordination, but also maintains its three-dimensional framework structure well after high-temperature pyrolysis, providing a large number of sites for Ru metal loading. This not only facilitates the dispersion of active sites, but also helps to accelerate the diffusion of reactant molecules and improve reaction efficiency.

[0026] (3) After high-temperature pyrolysis of the polymer, N-doped carbon materials are obtained. First, the N sites doped in the material can serve as anchoring sites to achieve uniform and stable dispersion of Ru atoms. Second, specific N sites can optimize the adsorption and activation of hydrogen chloride and acetylene molecules by metal sites. For example, during pyrolysis, we can directionally regulate the generation of pyridine N sites, which can significantly enhance the adsorption of hydrogen chloride and inhibit the adsorption of acetylene molecules, thereby improving the stability of metal sites in the reaction. Furthermore, the N sites doped in the material can also serve as reactive sites to improve the reaction activity of the catalyst.

[0027] (4) The catalyst was further modified by using phosphazene compounds and ionic liquids (especially morpholine ionic liquids) as promoters to regulate the chemical environment around the metal Ru sites, optimize the adsorption-desorption of reaction substrates / products at the active sites, inhibit the high-temperature reduction and aggregation of metal sites, inhibit the formation of reaction carbon deposits, and significantly improve the stability of Ru catalysts. Attached Figure Description

[0028] Figure 1 SEM image of the ruthenium-based catalyst Cat-1 prepared in Example 1.

[0029] Figure 2 TEM image of the ruthenium-based catalyst Cat-1 prepared in Example 1. Detailed Implementation

[0030] To better illustrate this patent, the following embodiments are provided. These embodiments are intended to enable those skilled in the art to understand the invention in more detail; however, the scope of the invention is not limited to these embodiments, and those skilled in the art can make some non-essential improvements and adjustments based on the above-described invention.

[0031] Example 1

[0032] (1) Vinylpyridine, vinylimidazolium, acrylonitrile, styrene, and divinylbenzene were added to ethyl acetate and stirred until homogeneous to obtain a mixed solution; then ruthenium trichloride was added to the aforementioned mixed solution, and the mixture was refluxed at 80°C for at least 6 hours to obtain solution A; solution A was naturally cooled to room temperature, and azobisisobutyronitrile was added as a polymerization initiator and stirred thoroughly to dissolve to obtain solution B; wherein the mass ratio of vinylimidazolium, acrylonitrile, styrene, divinylbenzene, and ethyl acetate was 1.0:0.5:0.5:0.5:1.0:15; the mass of ruthenium trichloride was 0.25% of the sum of the masses of vinylpyridine, vinylimidazolium, acrylonitrile, styrene, and divinylbenzene; and the mass of azobisisobutyronitrile was 2.5% of the sum of the masses of vinylpyridine, vinylimidazolium, acrylonitrile, styrene, and divinylbenzene.

[0033] (2) Transfer solution B to a high-pressure reactor with a polytetrafluoroethylene liner, and then place it in an electric heating drying oven with magnetic stirring. Use a gradient heating process to first heat the mixture from room temperature to 60°C (heating rate 2°C / min) to initiate the polymerization reaction. After reacting for 1 hour, turn off the stirring and maintain this temperature for 6 hours. Continue heating to 100°C (heating rate 5°C / min) and age for 6 hours. After the reaction is complete, allow the system to cool naturally. Take out the brown block polymer obtained from the reaction and let it dry naturally. After drying, crush the sample to 40–60 mesh for later use.

[0034] (3) Place the above powder sample in a high-temperature tube furnace and pre-oxidize the sample by heating it from room temperature to 300℃ (heating rate 1℃ / min) in an air atmosphere for 2 hours; then switch the air to ammonia and further heat it to 700℃ (heating rate 3℃ / min) for carbonization for 3 hours; after heat treatment, allow the sample to cool naturally to room temperature; the gas space velocity of air and ammonia is 15 h⁻¹. –1 ;

[0035] (4) Dissolve hexachlorotriphosphazene and N-ethyl-methylmorpholine bromide in deionized water, and impregnate the above carbonized sample with the above solution by equal volume impregnation method. After impregnation, the sample is dried at room temperature and then dried at 100℃ for 6h to obtain the target Ru catalyst, which is numbered Cat-1; wherein the molar ratio of ruthenium salt, phosphazene compound and morpholine ionic liquid is 1.0:0.2:0.5.

[0036] The catalyst preparation steps in Example 2 are the same as those in Example 1, except that copper chloride in step (1) is replaced with ruthenium acetylacetonate, and the resulting Ru catalyst is numbered Cat-2.

[0037] Example 3

[0038] The catalyst preparation steps in Example 3 are the same as those in Example 1, except that the mass ratio of vinylimidazole, acrylonitrile, styrene, divinylbenzene and ethyl acetate in step (1) is changed from 1.0:0.5:0.5:0.5:1.0:15 to 1.0:0.75:0.75:0.5:1.0:15. The resulting Ru catalyst is numbered Cat-3.

[0039] Example 4

[0040] The catalyst preparation steps in Example 4 are the same as those in Example 1, except that the mass ratio of vinylimidazole, acrylonitrile, styrene, divinylbenzene and ethyl acetate in step (1) is changed from 1.0:0.5:0.5:0.5:1.0:15 to 1.0:0.5:0.5:0.5:1.5:15. The resulting Ru catalyst is numbered Cat-4.

[0041] Example 5

[0042] The catalyst preparation steps in Example 5 are the same as those in Example 1, except that the mass of azobisisobutyronitrile in step (1) is changed from 2.5% to 4% of the sum of the masses of vinylpyridine, vinylimidazolium, acrylonitrile, styrene and divinylbenzene. The resulting Ru catalyst is numbered Cat-5.

[0043] Example 6

[0044] The catalyst preparation steps in Example 6 are the same as those in Example 1, except that the azobisisobutyronitrile in step (1) is replaced with azobisisoheptanenitrile, and the resulting Ru catalyst is numbered Cat-6.

[0045] Example 7

[0046] The catalyst preparation steps in Example 7 are the same as those in Example 1, except that the polymerization reaction temperature in step (2) is changed from 60°C to 65°C, and the resulting Ru catalyst is numbered Cat-7.

[0047] Example 8

[0048] The catalyst preparation steps in Example 8 are the same as those in Example 1, except that the heating rate of the polymerization reaction in step (2) is changed from 2℃ / min to 1℃ / min, and the resulting Ru catalyst is numbered Cat-8.

[0049] Example 9

[0050] The catalyst preparation steps in Example 9 are the same as those in Example 1, except that the polymer aging temperature in step (2) is changed from 100°C to 105°C, and the resulting Ru catalyst is numbered Cat-9.

[0051] Example 10

[0052] The catalyst preparation steps in Example 10 are the same as those in Example 1, except that the polymer aging heating rate in step (2) is changed from 5℃ / min to 1℃ / min, and the resulting Ru catalyst is numbered Cat-10.

[0053] Example 11

[0054] The catalyst preparation steps in Example 11 are the same as those in Example 1, except that the air pre-oxidation temperature in step (3) is changed from 300°C to 320°C, and the resulting Ru catalyst is numbered Cat-11.

[0055] Example 12

[0056] The catalyst preparation steps in Example 12 are the same as those in Example 1, except that the air pre-oxidation temperature in step (3) is changed from 300°C to 340°C, and the resulting Ru catalyst is numbered Cat-12.

[0057] Example 13

[0058] The catalyst preparation steps in Example 13 are the same as those in Example 1, except that the air pre-oxidation temperature in step (3) is changed from 300℃ to 350℃, and the resulting Ru catalyst is numbered Cat-13.

[0059] Example 14

[0060] The catalyst preparation steps in Example 14 are the same as those in Example 1, except that the air pre-oxidation time in step (3) is changed from 2h to 1h, and the resulting Ru catalyst is numbered Cat-14.

[0061] Example 15

[0062] The catalyst preparation steps in Example 15 are the same as those in Example 1, except that the air pre-oxidation time in step (3) is changed from 2h to 3h, and the resulting Ru catalyst is numbered Cat-15.

[0063] Example 16

[0064] The catalyst preparation steps in Example 16 are the same as those in Example 1, except that the carbonization temperature in step (3) is changed from 700℃ to 600℃, and the resulting Ru catalyst is numbered Cat-16.

[0065] Example 17

[0066] The catalyst preparation steps in Example 17 are the same as those in Example 1, except that the carbonization temperature in step (3) is changed from 700℃ to 900℃, and the resulting Ru catalyst is numbered Cat-17.

[0067] Example 18

[0068] The catalyst preparation steps in Example 18 are the same as those in Example 1, except that the carbonization atmosphere in step (3) is changed from ammonia to argon, and the resulting Ru catalyst is numbered Cat-18.

[0069] Example 19

[0070] The catalyst preparation steps in Example 19 are the same as in Example 1, except that the gas space velocity of air and ammonia in step (3) is 15 h⁻¹. –1 Change to 40h –1 The resulting Ru catalyst was designated Cat-19.

[0071] Example 20

[0072] The catalyst preparation steps in Example 20 are the same as those in Example 1, except that hexachlorocyclotriphosphazene in step (4) is replaced with hexafluorocyclotriphosphazene, and the resulting Ru catalyst is designated as Cat-20.

[0073] Example 21

[0074] The catalyst preparation steps in Example 21 are the same as those in Example 1, except that N-ethyl-methylmorpholine bromide in step (4) is replaced with N-butylpiperidine tetrafluoroborate, and the resulting Ru catalyst is numbered Cat-21.

[0075] Comparative Example 1

[0076] The purpose of changing the monomer composition is to compare with Example 1 to illustrate the effect of changing the monomer composition on the catalyst structure and performance.

[0077] The preparation steps of Comparative Example 1 are the same as those of Example 1, except that vinylimidazole and vinylpyridine in step (1) are removed, and the resulting Ru catalyst is numbered Cat-22.

[0078] Comparative Example 2

[0079] The purpose of changing the monomer composition is to compare with Example 1 to illustrate the effect of changing the monomer composition on the catalyst structure and performance.

[0080] The preparation steps of Comparative Example 1 are the same as those of Example 1, except that the crosslinking agent divinylbenzene in step (1) is removed, and the resulting Ru catalyst is numbered Cat-23.

[0081] Comparative Example 3

[0082] The purpose of reducing the amount of initiator azobisisobutyronitrile was to compare with Example 1 to illustrate the effect of initiator dosage on polymer structure.

[0083] The preparation steps of Comparative Example 3 are the same as those of Example 1, except that the mass of azobisisobutyronitrile in step (1) is changed from 2.5% of the sum of the masses of vinylimidazole, acrylonitrile and divinylbenzene to 5%, and the resulting Ru catalyst is numbered Cat-24.

[0084] Comparative Example 4

[0085] The purpose of lowering the pre-oxidation temperature of the polymer material is to compare it with Example 1 to illustrate the effect of pre-oxidation temperature on catalyst structure and performance.

[0086] The preparation steps of Comparative Example 4 are the same as those of Example 1, except that the air atmosphere pre-oxidation temperature in step (3) is changed from 300℃ to 200℃, and the resulting Ru catalyst is numbered Cat-25.

[0087] Comparative Example 5

[0088] The purpose of increasing the carbonization temperature of the polymer material is to compare it with Example 1 to illustrate the effect of carbonization temperature on the catalyst structure and performance.

[0089] The preparation steps of Comparative Example 5 are the same as those of Example 1, except that the ammonia carbonization temperature in step (3) is changed from 700℃ to 1200℃, and the resulting Ru catalyst is numbered Cat-26.

[0090] Comparative Example 6

[0091] The purpose of not adding phosphazene compounds as additives is to compare with Example 1 to illustrate the effect of the addition of hexachlorocyclotriphosphazene on Ru sites in the catalyst.

[0092] The preparation steps of Comparative Example 6 are the same as those of Example 1, except that the addition step of hexachlorocyclotriphosphazene in step (4) is removed, and the resulting Ru catalyst is numbered Cat-27.

[0093] Comparative Example 7

[0094] The purpose of not adding morpholine ionic liquid as an additive is to compare with Example 1 to illustrate the effect of the addition of N-ethyl-methylmorpholine bromide on Ru sites in the catalyst.

[0095] The preparation steps of Comparative Example 7 are the same as those of Example 1, except that the N-ethyl-methylmorpholine bromide in step (4) is removed, and the resulting Ru catalyst is numbered Cat-28.

[0096] Comparative Example 8

[0097] The purpose of changing the order of ruthenium salt introduction is to compare with Example 1 and to illustrate the effect of the ruthenium salt introduction scheme on catalyst performance.

[0098] The preparation steps of Comparative Example 8 are the same as those of Example 1, except that the addition step of ruthenium trichloride is changed from step (1) to step (4), and the resulting Ru catalyst is numbered Cat-29.

[0099] The evaluation process and conditions for catalysts are as follows:

[0100] (1) 0.5 mL of catalyst was mixed with 0.5 mL of quartz sand and placed in a fixed-bed reactor. The temperature was raised to 160 °C and held for 1 h under a flowing nitrogen atmosphere, wherein the volume hourly space velocity of nitrogen was 30 h⁻¹. –1 ;

[0101] (2) Turn off the nitrogen gas and switch to flowing hydrogen chloride gas, and keep the temperature constant for 1 hour, wherein the volume hourly space velocity of hydrogen chloride is 30 h⁻¹. –1 ;

[0102] (3) Acetylene gas is introduced, and the volume hourly space velocity of acetylene is 360 h⁻¹. –1 The molar ratio of hydrogen chloride to acetylene is 1.2:1;

[0103] The gas after the reaction was quantitatively analyzed using gas chromatography. Samples were taken every 0.5 h, and the point after 1 h of reaction was selected as the initial activity. The performance data of acetylene hydrochlorination reaction of different Ru catalysts are shown in the table:

[0104]

[0105]

Claims

1. A highly dispersed Ru catalyst for the preparation of vinyl chloride via a fixed-bed acetylene process, characterized in that... The catalyst is prepared according to the following steps: (1) Vinylpyridine, vinylimidazolium, acrylonitrile, styrene and divinylbenzene were added to ethyl acetate and stirred until homogeneous to obtain a mixed solution; then ruthenium salt was added to the aforementioned mixed solution and refluxed at 80–100 °C for at least 6 h to obtain solution A; Solution A was naturally cooled to room temperature, and an azo compound was added as a polymerization initiator. The mixture was stirred thoroughly to dissolve the solution and obtain solution B. (2) Transfer solution B to a high-pressure reactor with a polytetrafluoroethylene liner. Under stirring, use a gradient heating process. First, heat the mixture from room temperature to 60–65°C at a heating rate of 1–3°C / min to initiate the polymerization reaction. After reacting for 1–2 hours, turn off the stirring and maintain the temperature for 6–8 hours. Then, continue heating the mixture at a heating rate of 5–10°C / min to 100–105°C for aging for at least 6 hours. After that, allow it to cool naturally to room temperature. Take out the block polymer obtained from the reaction and let it dry naturally. After drying, crush the sample to 40–60 mesh for later use. (3) The above polymer powder was placed in a high-temperature tube furnace and the sample was heat-treated by the "low-temperature pre-oxidation + high-temperature carbonization" process. First, the sample was pre-oxidized by heating from room temperature to 300–350°C at a heating rate of 1–3°C / min in a flowing air atmosphere for 1–3 h. Then, the air was switched to a flowing non-oxidizing atmosphere and the sample was further carbonized by heating to 600–1000°C at a heating rate of 1–3°C / min for 2–3 h. After the carbonization was completed, the sample was naturally cooled to room temperature to obtain the carbonized sample. (4) Dissolve the phosphazene compound and ionic liquid in deionized water or ethanol, and impregnate them into the carbonized sample using an equal-volume impregnation method. Dry the impregnated sample at 80–100℃ for 4–6 hours to obtain the Ru-based catalyst. The phosphazene compound is one or more of hexachlorotriphosphazene, phenoxycyclophosphazene, hexafluorocyclotriphosphazene, ethoxy(pentafluoro)cyclotriphosphazene, pentafluoro(phenoxy)cyclotriphosphazene, and phosphazene ligand P1-tert-octyl. The ionic liquid is one or more of imidazole ionic liquid, piperidine ionic liquid, quaternary ammonium salt ionic liquid, quaternary phosphonium salt ionic liquid, pyrrolidine ionic liquid, morpholine ionic liquid, and pyridine ionic liquid. The molar ratio of ruthenium salt, phosphazene compound, and ionic liquid is 1.0:0.05–1.0:0.5–1.

5.

2. The Ru catalyst as described in claim 1, characterized in that: In step (1), the mass ratio of vinylpyridine, vinylimidazolium, acrylonitrile, styrene, divinylbenzene and ethyl acetate is 1.0:0.5–1.0:0.5–2.0:0.5–1.5:0.3–1.5:

15.

3. The Ru catalyst as described in claim 1, characterized in that: In step (1), the ruthenium salt is one or more of the following: ruthenium acetate, ruthenium acetylacetonate, ruthenium trichloride, ruthenium iodide, ruthenium bromide, dodecyltriruthenium, dichlorophenylruthenium(II) dimer, ammonium hexachlororuthenium, tetralactam perruthenium, dichlorotetra(triphenylphosphine)ruthenium, tris(2,2-bipyridine)ruthenium chloride, tris(triphenylphosphine) dichloride, ethylenedicarbonylruthenium, bis(pentamethylcyclopentadiene)ruthenium, tris(2,2'-bipyridine) dichloride, and (1,5-cyclooctadiene) dichloride. The mass of the ruthenium salt is 0.25%–5% of the sum of the masses of vinylpyridine, vinylimidazole, acrylonitrile, styrene, and divinylbenzene.

4. The Ru catalyst as described in claim 1, characterized in that: In step (1), the azo initiator is one or a mixture of azobisisobutyronitrile and azobisisoheptanenitrile, and the mass of the azo compound is 1.5%–4% of the sum of the masses of vinylpyridine, vinylimidazole, acrylonitrile, styrene and divinylbenzene.

5. The Ru catalyst as described in claim 1, characterized in that: In step (3), the non-oxidizing atmosphere is one or more of nitrogen, argon, helium, ammonia, and hydrogen; the gas volume hourly space velocity (VHSV) of air or the non-oxidizing atmosphere is 10–40 h⁻¹. –1 .

6. A method of using the Ru catalyst according to claims 1-5, characterized by specifically including the following steps: (1) Place the catalyst in a fixed-bed reactor and heat it to 120–220 °C under a flowing nitrogen atmosphere and hold it at that temperature for at least 1 h, wherein the volume hourly space velocity of nitrogen is 15–45 h⁻¹. –1 ; (2) Turn off the nitrogen gas and switch to flowing hydrogen chloride gas, and keep it at a constant temperature for at least 1 hour, with a hydrogen chloride volume hourly space velocity of 15–45 h⁻¹. –1 ; (3) After adjusting the reactor temperature to 120–240℃, acetylene gas is introduced, with an acetylene volume hourly space velocity of 15–400 h⁻¹. –1 The molar ratio of hydrogen chloride to acetylene is controlled to be 1.05–1.3:1; (4) Use gas chromatography to perform quantitative analysis of the gas after the reaction.

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