A nitrogen-sulfur co-doped activated carbon supported rhodium catalyst, a preparation method and application thereof

Abstract

The present application belongs to the technical field of chemical engineering catalysts, and particularly relates to a nitrogen-sulfur co-doped activated carbon supported rhodium catalyst, a preparation method and application thereof. Specifically, the catalyst comprises a carrier and an active component rhodium supported on the carrier; the carrier is nitrogen-sulfur co-doped activated carbon; the theoretical loading amount of the active component rhodium is 0.5-2.0 wt% of the total mass of the nitrogen-sulfur co-doped activated carbon supported rhodium catalyst; the nitrogen and sulfur sources in the nitrogen-sulfur co-doped activated carbon are thiourea; and the mass ratio of the thiourea to the activated carbon is (0.5-3):1. The catalyst exhibits excellent catalytic performance in the reaction of methanol carbonylation to acetic acid, and the methanol conversion rate reaches 96% and the acetic acid selectivity reaches 88.4% after 3 h of reaction, and the conversion rate remains above 93% after three cycles. The present application effectively improves the loading efficiency and dispersity of rhodium by nitrogen-sulfur co-doping, significantly improves the catalytic activity and selectivity of the target product, and has good industrial application prospects.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering catalyst technology, specifically relating to a nitrogen-sulfur co-doped activated carbon supported rhodium catalyst, its preparation method, and its application. Background Technology

[0002] Acetic acid is an important basic chemical raw material, widely used in the production of vinyl acetate, acetic anhydride, purified terephthalic acid, etc. Currently, industrial acetic acid production mainly employs the methanol carbonylation method, specifically the homogeneous rhodium-iodine catalytic system (Monsanto process) and the iridium-based catalytic system (Cativa process). TM The primary method is to use homogeneous catalysts. While homogeneous systems exhibit high activity and selectivity, they suffer from challenges such as difficulty in separating the catalyst from the product, high costs of precious metal recovery, and strong corrosivity of the reaction system. Constructing heterogeneous catalysts by loading rhodium species in atomic form onto a solid support is an effective way to achieve catalyst recovery and reuse, and improve atom economy.

[0003] Activated carbon is a commonly used heterogeneous catalyst support due to its high specific surface area, abundant pores, and good chemical stability. However, unmodified activated carbon lacks anchoring sites on its surface to form strong interactions with noble metals, leading to metal agglomeration, low loading, and poor catalytic activity. Heteroatom doping (such as N and S) can introduce coordination sites, enhance metal-support interactions, and stabilize single-atom or sub-nanometer clusters. Existing studies have shown that nitrogen doping can improve the dispersibility of rhodium, but the regulatory effect of nitrogen doping alone is limited. Nitrogen-sulfur co-doping can further optimize the electronic structure and coordination environment of the metal center, but current research on nitrogen-sulfur co-doped activated carbon-supported rhodium catalysts for methanol carbonylation is still insufficient.

[0004] Therefore, developing a rhodium catalyst supported on nitrogen-sulfur co-doped activated carbon is of great significance. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of existing technologies by providing a nitrogen-sulfur co-doped activated carbon supported rhodium catalyst, its preparation method, and its application. The nitrogen-sulfur co-doped activated carbon supported rhodium catalyst synthesized by this invention not only possesses excellent catalytic performance for the methanol carbonylation to acetic acid production but also exhibits good cycle stability.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] The first aspect of this invention provides a nitrogen-sulfur co-doped activated carbon supported rhodium catalyst, comprising a support and an active component rhodium supported on the support; the support is nitrogen-sulfur co-doped activated carbon; the theoretical loading of the active component rhodium is 0.5~2.0 wt% of the total mass of the nitrogen-sulfur co-doped activated carbon supported rhodium catalyst; wherein the nitrogen and sulfur in the nitrogen-sulfur co-doped activated carbon are derived from thiourea; and the mass ratio of thiourea to activated carbon is (0.5~3):1.

[0008] The theoretical loading of the active component rhodium is 1 wt% of the total mass of the nitrogen-sulfur co-doped activated carbon supported rhodium catalyst.

[0009] The mass ratio of thiourea to activated carbon is (2~3):1.

[0010] In some embodiments of the present invention, the mass ratio of thiourea to activated carbon is 2:1.

[0011] A second aspect of this invention provides a method for preparing a rhodium catalyst supported on nitrogen-sulfur co-doped activated carbon, comprising the following steps:

[0012] Step 1: Mix thiourea and activated carbon evenly in deionized water, collect the solid by centrifugation after hydrothermal reaction, calcine the solid under an inert atmosphere, wash and dry after natural cooling to obtain nitrogen and sulfur co-doped activated carbon.

[0013] Step 2: Weigh out rhodium trichloride hydrate according to the theoretical loading of the active component rhodium and add it to the suspension of nitrogen-sulfur co-doped activated carbon. Add anhydrous ethanol as a reducing agent, heat and reflux the reaction, cool and centrifuge to collect the solid, wash and dry it to obtain the nitrogen-sulfur co-doped activated carbon supported rhodium catalyst.

[0014] In step 1, the mass ratio of thiourea to activated carbon is (0.5~3):1; the mass-volume ratio of activated carbon to deionized water is 1:10 g / mL.

[0015] In some embodiments of the present invention, in step 1, the mass ratio of thiourea to activated carbon is (2~3):1.

[0016] In some embodiments of the present invention, in step 1, the mass ratio of thiourea to activated carbon is 2:1.

[0017] In step 1, the hydrothermal reaction is carried out under the following conditions: temperature 150~200℃, time 4~8h.

[0018] In some embodiments of the present invention, in step 1, the hydrothermal reaction is carried out under the following conditions: temperature 180°C and time 5 hours.

[0019] In step 1, the centrifugation is performed under the following conditions: centrifugation at 8000 rpm for 10 minutes.

[0020] In step 1, the calcination is carried out under the following conditions: under an inert atmosphere, the temperature is increased to 700-900℃ at a rate of 1-5℃ / min, and held for 1-3 hours.

[0021] In some embodiments of the present invention, in step 1, the calcination is carried out under the following conditions: under an inert atmosphere, the temperature is increased to 800°C at a rate of 1°C / min and held for 2 hours.

[0022] In some embodiments of the present invention, step 1 includes acid washing and water washing, with the following conditions: washing with 1 mol / L hydrochloric acid solution for 6 hours with stirring, followed by washing with deionized water until neutral.

[0023] In some embodiments of the present invention, in step 1, the drying conditions are: vacuum drying at 120°C overnight.

[0024] In step 2, the solvent in the suspension of nitrogen-sulfur co-doped activated carbon is deionized water, and the mass-to-volume ratio of nitrogen-sulfur co-doped activated carbon to deionized water is 1:50 g / mL; the volume ratio of anhydrous ethanol to the suspension of nitrogen-sulfur co-doped activated carbon is 1:10.

[0025] In step 2, the heating reflux reaction is carried out under the following conditions: temperature 80~90℃, time 2~6h.

[0026] In some embodiments of the present invention, in step 2, the heating reflux reaction is carried out under the following conditions: temperature 85°C, time 4h.

[0027] In some embodiments of the present invention, in step 2, the washing is performed under the following conditions: alternating centrifugal washing with deionized water and anhydrous ethanol three times.

[0028] In some embodiments of the present invention, in step 2, the drying conditions are: vacuum drying at 120°C overnight.

[0029] The third aspect of this invention provides the application of a rhodium catalyst supported on nitrogen-sulfur co-doped activated carbon in the carbonylation of methanol to prepare acetic acid.

[0030] The mass-to-volume ratio of the nitrogen-sulfur co-doped activated carbon-supported rhodium catalyst in the methanol carbonylation to acetic acid feedstock is 1:100 g / mL.

[0031] The conditions for preparing acetic acid by methanol carbonylation are as follows: reaction temperature 180~200℃, carbon monoxide pressure 3~5MPa, reaction time 2~5h, stirring speed 200~400rpm; the raw material molar ratio is methanol: iodomethane: water = (40~50):(25~30):(20~30).

[0032] In some embodiments of the present invention, the conditions for preparing acetic acid by methanol carbonylation are: reaction temperature 190°C, carbon monoxide pressure 4 MPa, reaction time 3 h, stirring speed 300 rpm; and the raw material molar ratio is methanol: iodomethane: water = 47:28:25.

[0033] In some embodiments of the present invention, rhodium catalysts (AC-Rh, AC-(NS)) are supported on activated carbon with different nitrogen and sulfur doping ratios. 0.5 A comparison of the catalytic performance of rhodium-doped activated carbon catalysts (AC-(NS)1-Rh, AC-(NS)2-Rh, and AC-(NS)3-Rh) showed that with increasing nitrogen and sulfur doping, methanol conversion initially increased and then decreased, reaching a peak of 96.0% with AC-(NS)2-Rh. Acetic acid selectivity significantly improved to over 88% when using AC-(NS)2-Rh or AC-(NS)3-Rh. In contrast, the undoped rhodium-supported activated carbon catalyst AC-Rh exhibited a methanol conversion of only 88.0% and an acetic acid selectivity of 81.4%, both significantly lower than the doped samples. This demonstrates that appropriate nitrogen and sulfur co-doping can simultaneously improve both conversion and target product selectivity, proving the promising application of nitrogen-sulfur co-doped rhodium-supported activated carbon catalysts in the carbonylation of methanol to acetic acid.

[0034] Beneficial effects:

[0035] This invention utilizes a simple hydrothermal-calcination method and a one-step hydrothermal reduction strategy to introduce thiourea as a single nitrogen and sulfur source into an activated carbon framework, preparing a nitrogen-sulfur co-doped activated carbon support. Rhodium species are then loaded onto the support surface via ethanol reduction, yielding a rhodium catalyst supported on the nitrogen-sulfur co-doped activated carbon. Nitrogen-sulfur co-doping provides abundant chemical anchoring sites for rhodium, enabling it to be highly dispersed in both zero-valent and trivalent forms, effectively suppressing metal agglomeration. Simultaneously, the polar doping sites enrich water molecules in the reaction system through hydrogen bonding, creating a locally high-water-concentration microenvironment near the rhodium active center, promoting the hydrolysis of the acetyl intermediate to acetic acid, and significantly improving the selectivity for acetic acid. This catalyst exhibits excellent catalytic activity and good cycling stability in the methanol carbonylation to acetic acid reaction, and has been successfully used for the highly selective synthesis of acetic acid from methanol carbonylation. Attached Figure Description

[0036] The present invention will be further described in detail below with reference to the accompanying drawings, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0037] Figure 1 The images shown are SEM images of different samples in the embodiments of the present invention and EDS elemental distribution diagrams of AC-(NS)2-Rh catalyst before and after the catalytic reaction.

[0038] Figure 2 This is a comparison of XPS images of AC-(NS)2 support and AC-(NS)2-Rh catalyst in the embodiments of the present invention.

[0039] Figure 3 These are XRD patterns of different samples in the embodiments of the present invention.

[0040] Figure 4 This is a comparison chart of the catalytic performance of catalysts with different nitrogen and sulfur doping ratios in the embodiments of the present invention. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0042] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0043] Example 1: Preparation of nitrogen-sulfur co-doped activated carbon support

[0044] The activated carbon was washed three times with deionized water to remove soluble impurities and then dried at 120°C for later use.

[0045] Weigh 1.0 g of pretreated activated carbon and corresponding amounts of thiourea (0 g, 0.5 g, 1.0 g, 2.0 g, and 3.0 g) according to the mass ratios of thiourea to activated carbon of 0:1, 0.5:1, 1:1, 2:1, and 3:1, respectively. Add each to 10 mL of deionized water and sonicate until the thiourea is completely dissolved and the activated carbon is uniformly dispersed, obtaining a suspension. Transfer the suspension to a stainless steel high-pressure hydrothermal reactor with a polytetrafluoroethylene liner, seal it, and maintain the reaction temperature at 180 °C for 5 h. After natural cooling, collect the solid by centrifugation at 8000 rpm for 10 min, wash three times with deionized water, and dry overnight at 120 °C.

[0046] The dried solid was placed in a tube furnace and heated to 800℃ at a heating rate of 1℃ / min under an argon atmosphere, and held at that temperature for 2 hours. After natural cooling, it was washed with 1 mol / L hydrochloric acid solution with stirring for 6 hours, then washed with deionized water until neutral, and vacuum dried at 120℃ overnight to obtain the nitrogen-sulfur co-doped activated carbon support. Based on the mass ratio of thiourea to activated carbon, the supports were named AC support (0:1) and AC-(NS), respectively. 0.5Vector (0.5:1), AC-(NS)1 vector (1:1), AC-(NS)2 vector (2:1), AC-(NS)3 vector (3:1).

[0047] Example 2: Preparation of rhodium catalyst supported on nitrogen-sulfur co-doped activated carbon

[0048] Weigh out 1.0g each of the AC carrier and AC-(NS) prepared in Example 1. 0.5 Supports AC-(NS)1, AC-(NS)2, and AC-(NS)3 were added to a flask containing 50 mL of deionized water and magnetically stirred at room temperature for 30 min to disperse them evenly, obtaining a suspension. Based on a theoretical rhodium loading of 1 wt% (the theoretical loading is the mass ratio of the active component rhodium to the rhodium catalyst supported on nitrogen-sulfur co-doped activated carbon), 26.54 mg of rhodium trichloride hydrate (RhCl3·xH2O, Rh mass fraction 39%) was weighed and added to the above suspension, and stirring continued until completely dissolved. A reflux condenser was installed, and the mixture was transferred to an oil bath and heated to 85 °C. After the temperature stabilized, 5 mL of anhydrous ethanol was added as a reducing agent, and the reaction was maintained at this temperature with stirring for 4 h. After natural cooling, the mixture was centrifuged, and the solid was washed three times alternately with deionized water and anhydrous ethanol, dried under vacuum at 120 °C overnight, and thoroughly ground to obtain AC-Rh and AC-(NS) respectively. 0.5 -Rh, AC-(NS)1-Rh, AC-(NS)2-Rh and AC-(NS)3-Rh catalysts.

[0049] Example 3: Catalyst Characterization

[0050] The structure and microstructure of the rhodium catalyst supported on nitrogen-sulfur co-doped activated carbon were characterized using AC-(NS)2-Rh as an example. Field emission scanning electron microscopy (SEM) was used to observe the AC support, AC-(NS)2 support, and AC-(NS)2-Rh catalyst. Furthermore, energy-dispersive X-ray spectroscopy (EDS) was used to analyze the elemental distribution in the AC-(NS)2-Rh catalyst before and after the catalytic reaction. Figure 1 SEM images of different samples and EDS elemental distribution maps of AC-(NS)2-Rh catalyst before and after the catalytic reaction are shown. Figure 1 In the figure, 'a' is the SEM image of the unmodified AC carrier, which shows that the material exhibits a graphite-like layered stacking structure. Figure 1 b in the figure is a SEM image of the AC-(NS)2 carrier. As can be seen from the figure, the overall structure remains intact, and a small number of mesopores appear on the surface. Figure 1 In the figure, c is the SEM image of the AC-(NS)2-Rh catalyst, and it can be seen from the figure that there is no obvious change in morphology. Figure 1 d~ Figure 1The h in the figure is the EDS elemental mapping diagram of the AC-(NS)2-Rh catalyst before the catalytic reaction. As can be seen from the figure, C, N, S and Rh elements are evenly distributed. Figure 1 i~ Figure 1 In the figure, m is the EDS elemental mapping of the AC-(NS)2-Rh catalyst after the catalytic reaction. As can be seen from the figure, Rh still maintains a uniform distribution.

[0051] X-ray photoelectron spectroscopy (XPS) was used to analyze the AC-(NS)2 support and AC-(NS)2-Rh catalyst. Figure 2 The images show a comparison of XPS values ​​for the AC-(NS)2 support and the AC-(NS)2-Rh catalyst. Figure 2 In the figure, 'a' represents the N1s spectra of the AC-(NS)2 support and the AC-(NS)2-Rh catalyst. As shown in the figure, the N1s spectra of both the AC-(NS)2 support and the AC-(NS)2-Rh catalyst show characteristic peaks of pyridine N (398.5 eV) and pyrrole N (400.9 eV). The peak area of ​​pyridine N decreases significantly after Rh loading, indicating that pyridine N participates in Rh coordination. Figure 2 In the figure, b represents the S2p spectrum of AC-(NS)2 support and AC-(NS)2-Rh catalyst. As can be seen from the figure, the characteristic peaks of thiophene S (164.0 eV and 165.2 eV) appear in the S2p spectrum. After loading Rh, the oxidized sulfur peak is enhanced at 168.0 eV, indicating that some S also participates in Rh coordination. Figure 2 In the figure, c represents the Rh3d spectra of the AC-(NS)2 support and the AC-(NS)2-Rh catalyst. As can be seen from the figure, the Rh3d spectrum of the AC-(NS)2 support only shows trivalent Rh (309.7 eV, 314.6 eV), while the AC-(NS)2-Rh catalyst shows both zero-valent Rh (307.9 eV, 312.4 eV) and trivalent Rh (310.2 eV, 314.3 eV), which confirms that nitrogen and sulfur co-doping promotes the atomic-level dispersion of Rh and the coexistence of multiple valence states.

[0052] X-ray diffraction (XRD) was used to analyze the phase composition of different samples. Figure 3 The images show the XRD patterns of different samples in Example 1. Figure 3 In the figure, 'a' represents the XRD patterns of AC support, AC-Rh catalyst, AC-(NS)2 support, and AC-(NS)2-Rh catalyst. As can be seen from the figure, all samples show characteristic broad peaks of amorphous carbon at 2θ≈22° and 43°. Figure 3 In this context, b represents AC-(NS). 0.5 XRD patterns of AC-Rh, AC-(NS)1-Rh, AC-(NS)2-Rh and AC-(NS)3-Rh catalysts. The figures show that the low-doped samples (AC-Rh catalyst, AC-(NS)3-Rh catalyst, AC-(NS)4 ...0.5 The -Rh catalyst showed a weak diffraction peak at 32.6°, corresponding to Rh oxide; as the doping ratio increased, the peak gradually weakened and disappeared completely in AC-(NS)2-Rh catalyst and AC-(NS)3-Rh catalyst, indicating that high doping can effectively suppress Rh agglomeration and promote high dispersion.

[0053] The actual rhodium loading in AC-Rh and AC-(NS)2-Rh catalysts was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Table 1 shows the analytical results. The average value of three parallel tests was taken: the rhodium loading in AC-Rh catalyst was 0.748 wt%, and the rhodium loading in AC-(NS)2-Rh catalyst was 0.795 wt.%, an increase of about 6.3%.

[0054] Table 1. ICP-OES elemental analysis results of AC-Rh and AC-(NS)2-Rh catalysts

[0055]

[0056] Example 4: Evaluation of the catalytic performance of methanol carbonylation

[0057] In a 100 mL high-pressure reactor, 0.2 g of the nitrogen-sulfur co-doped activated carbon-supported rhodium catalyst prepared in Example 1 was added. The reaction substrate was prepared at a molar ratio of methanol: iodomethane: water = 47:28:25, with a total feed volume of 20 mL. The air in the reactor was replaced three times with CO, and then CO was introduced to an initial pressure of 4 MPa. The temperature was raised to 190 °C, and the stirring rate was 300 rpm for 3 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The liquid product was collected and analyzed by gas chromatography (TCD detector, Porapak-Q packed column, column temperature 140 °C, vaporization chamber and detector 160 °C, carrier gas H2 flow rate 40 mL / min). Quantification was performed using the external standard method. The formulas for calculating methanol conversion, acetic acid selectivity, and methyl acetate selectivity are as follows:

[0058] Methanol conversion rate = (moles of methanol consumed in the reaction / initial moles of methanol) × 100%;

[0059] Acetic acid selectivity = (moles of acetic acid / (2 × moles of methyl acetate + moles of acetic acid)) × 100%;

[0060] methyl acetate selectivity = (2 × number of moles of methyl acetate / (2 × number of moles of methyl acetate + number of moles of acetic acid)) × 100%.

[0061] Figure 4 Table 2 shows the comparison results of the catalytic performance of catalysts with different nitrogen and sulfur doping ratios. Among them, Figure 4 In the graph, 'a' represents the methanol conversion rate (bar chart). Figure 4In the figure, b is a selectivity bar chart of acetic acid and methyl acetate; Figure 4 In the figure, 'c' represents the yield curve of acetic acid. (From...) Figure 4 As shown in Table 2, with increasing nitrogen and sulfur doping levels, methanol conversion initially increased and then decreased, reaching a peak of 96.0% with AC-(NS)2-Rh. Acetic acid selectivity significantly improved to over 88% when using AC-(NS)2-Rh or AC-(NS)3-Rh. In contrast, the methanol conversion rate of the undoped activated carbon-supported rhodium catalyst AC-Rh was only 88.0%, and the acetic acid selectivity was 81.4%, both significantly lower than the doped samples. This indicates that appropriate nitrogen and sulfur co-doping can simultaneously improve both conversion rate and target product selectivity.

[0062] Table 2 Catalytic performance of catalysts with different nitrogen and sulfur doping ratios

[0063]

[0064] The AC-(NS)2-Rh catalyst with the best catalytic effect was further subjected to three repeated recovery experiments. After each reaction, the reaction solution was centrifuged to collect the catalyst, washed three times with anhydrous methanol, dried under vacuum at 120°C overnight, and then the catalytic reaction was carried out again under the conditions of Example 4. Figure 4 The value of 'd' in the figure represents the results of three cycles of stability testing of the AC-(NS)2-Rh catalyst. The methanol conversion rates for the three cycles were 95.99%, 93.96%, and 93.85%, with an average of 94.60%. The acetic acid selectivity rates were 88.44%, 84.41%, and 85.72%, with an average of 86.19%. The relative standard deviation (RSD) of the conversion rate was 1.27%, and the RSD of the selectivity was 2.39%, indicating that the catalyst has good stability for repeated use.

[0065] This invention provides a nitrogen-sulfur co-doped activated carbon supported rhodium catalyst, its preparation method, and its application. Many methods and approaches exist to achieve this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A rhodium catalyst supported on nitrogen-sulfur co-doped activated carbon, characterized in that, The catalyst comprises a support and an active component, rhodium, supported on the support; the support is nitrogen-sulfur co-doped activated carbon; the theoretical loading of the active component, rhodium, is 0.5 to 2.0 wt% of the total mass of the rhodium catalyst supported on the nitrogen-sulfur co-doped activated carbon; wherein the nitrogen and sulfur in the nitrogen-sulfur co-doped activated carbon are derived from thiourea; and the mass ratio of thiourea to activated carbon is (0.5 to 3):

1.

2. The nitrogen-sulfur co-doped activated carbon supported rhodium catalyst according to claim 1, characterized in that, The theoretical loading of the active component rhodium is 1 wt% of the total mass of the nitrogen-sulfur co-doped activated carbon supported rhodium catalyst.

3. The nitrogen-sulfur co-doped activated carbon supported rhodium catalyst according to claim 1 or 2, characterized in that, The mass ratio of thiourea to activated carbon is (2~3):

1.

4. The method for preparing the rhodium catalyst supported on nitrogen-sulfur co-doped activated carbon according to any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Mix thiourea and activated carbon evenly in deionized water, collect the solid by centrifugation after hydrothermal reaction, calcine the solid under an inert atmosphere, wash and dry after natural cooling to obtain nitrogen and sulfur co-doped activated carbon. Step 2: Weigh out rhodium trichloride hydrate according to the theoretical loading of the active component rhodium and add it to the suspension of nitrogen-sulfur co-doped activated carbon. Add anhydrous ethanol as a reducing agent, heat and reflux the reaction, cool and centrifuge to collect the solid, wash and dry it to obtain the nitrogen-sulfur co-doped activated carbon supported rhodium catalyst.

5. The preparation method according to claim 4, characterized in that, In step 1, the mass ratio of thiourea to activated carbon is (0.5~3):1; the mass-volume ratio of activated carbon to deionized water is 1:10 g / mL.

6. The preparation method according to claim 4, characterized in that, In step 1, the hydrothermal reaction is carried out under the following conditions: temperature 150~200℃, time 4~8h.

7. The preparation method according to claim 4, characterized in that, In step 1, the calcination is carried out under the following conditions: under an inert atmosphere, the temperature is increased to 700-900℃ at a rate of 1-5℃ / min, and held for 1-3 hours.

8. The preparation method according to claim 4, characterized in that, In step 2, the solvent in the suspension of nitrogen-sulfur co-doped activated carbon is deionized water, and the mass-to-volume ratio of nitrogen-sulfur co-doped activated carbon to deionized water is 1:50 g / mL; the volume ratio of anhydrous ethanol to the suspension of nitrogen-sulfur co-doped activated carbon is 1:

10.

9. The preparation method according to claim 4, characterized in that, In step 2, the heating reflux reaction is carried out under the following conditions: temperature 80~90℃, time 2~6h.

10. The application of the nitrogen-sulfur co-doped activated carbon supported rhodium catalyst according to any one of claims 1 to 3 in the preparation of acetic acid by methanol carbonylation.

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