Preparation of cobalt sulfide catalyst and its application in hydrogenation of hydrogen sulfide and carbon dioxide to methyl mercaptan

Abstract

The application discloses a kind of Co x S y Preparation method and application of catalyst, belong to the technical field of catalyst preparation.The method is by using different solvents, the morphology of Co x S y Is controlled, to synthesize four kinds of Co x S y Catalyst with different morphology characteristics.The catalyst preparation method is simple, and the repeatability is strong.The obtained Co x S y Catalyst has high specific surface area, can expose more active sites, make reactant and catalyst active site contact fully, simultaneously, the catalyst has stronger sulfur resistance, and has abundant sulfur vacancy, is favorable to H2S and CO2 Adsorption and activation.Therefore, the obtained Co x S y Catalyst shows high catalytic activity in the reaction of H2S and CO2 hydrogenation.

Description

Technical Field

[0001] The present invention relates to a preparation technology of an environmental catalyst and its application field, and in particular to a Co x S y A preparation method of a catalyst and its application in hydrogenation of H2S and CO2 to produce methyl mercaptan. Background Art

[0002] Production processes such as oil refining and coal chemical processing not only emit H2S gas but also produce large amounts of CO2. H2S can severely corrode production equipment and poison catalysts. CO2 can also contribute to environmental problems such as global warming. Therefore, controlling H2S pollution and reducing CO2 emissions are imperative. Among various sulfur-containing chemicals, methyl mercaptan (CH3SH) serves as an important organic synthesis intermediate, commonly used in the preparation of chemical products such as lysine protein, chlorpyrifos insecticide, wool dyeing auxiliaries, gas odorants, and fragrances, enjoying a wide range of applications. However, my country's methyl mercaptan production process is immature, particularly due to a lack of low-cost, green, and clean production technologies. This has led to a significant lag in domestic methyl mercaptan production capacity, a significant market gap, and heavy reliance on imports. Therefore, a one-step synthesis of methyl mercaptan using H2S and CO2 as raw materials can not only simultaneously convert H2S and CO2 but also produce high-value-added products. This method offers the advantages of readily available raw materials and significant prospects for industrial application, maximizing resource utilization.

[0003] Currently, the mainstream routes for synthesizing methyl mercaptan include the methanol mercaptanation method and the high-sulfur syngas method (H2S / CO / H2). The methanol mercaptanation method is a relatively mature commercial technology, but it requires high energy and equipment investment and produces large amounts of acidic CO2, which is detrimental to the ecological environment. The high-sulfur syngas method has attracted considerable attention for its advantages, including high atomic efficiency, simple process, and low production equipment costs. Replacing CO with CO2, producing methyl mercaptan using H2S, CO2, and H2 as raw materials, not only reduces greenhouse gases but also simultaneously converts and utilizes the acidic H2S gas. Summary of the Invention

[0004] The purpose of the present invention is to provide a Co x S y The preparation method and application of the catalyst are used to solve the problems in the prior art of difficult activation of CO2 and low conversion rate of methyl mercaptan generated by the reaction of H2S and CO2. x S y The catalyst has a spherical morphology composed of small particles, which has a higher Co 2+ / Co 3+The high specific surface area and abundant sulfur vacancies can improve the reaction activity, and the higher specific surface area exposes more active sites, thus efficiently catalyzing the reaction of H2S and CO2 to produce methyl mercaptan.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A Co x S y The catalyst, the preparation method of which comprises the following steps:

[0007] 1) Add the cobalt source to the solvent, stir continuously for half an hour, and then allow to stand or undergo solvothermal reaction to obtain a precursor;

[0008] 2) Mixing the obtained precursor with a sulfur source and stirring continuously for half an hour, and then performing a hydrothermal reaction;

[0009] 3) After the reaction is cooled to room temperature, the obtained precipitate is filtered, washed, and dried to obtain the Co x S y catalyst;

[0010] Where x is an integer from 1 to 9, and y is an integer from 1 to 8.

[0011] Furthermore, the cobalt source in step 1) is cobalt nitrate hexahydrate (Co(NO3)2·6H2O) or cobalt chloride hexahydrate (CoCl2·6H2O), preferably cobalt nitrate hexahydrate.

[0012] Furthermore, the solvent in step 1) is one or more of water, methanol, isopropanol and glycerol, preferably isopropanol and glycerol (V 异丙醇 :V 甘油 =4:1) mixed solution.

[0013] Furthermore, the standing time in step 1) is 0 to 24 hours.

[0014] Furthermore, the solvothermal reaction in step 1) is carried out at a temperature of 180° C. for 2 to 5 hours, preferably 3 hours.

[0015] Furthermore, in step 1), 2-methylimidazole or the like may be further added as a template agent to carry out the reaction.

[0016] Furthermore, in step 2), the sulfur source is thiourea or thioacetamide, preferably thiourea.

[0017] Furthermore, the temperature of the hydrothermal reaction in step 2) is 120° C. to 180° C., and the time is 8 to 24 hours, preferably 12 hours.

[0018] Furthermore, the filtration and washing in step 3) is performed by washing with deionized water and ethanol three times in turn.

[0019] Furthermore, the drying in step 3) is performed by vacuum drying at a temperature of 80°C.

[0020] The catalyst prepared by the above method is a petal-shaped Co x S y , spherical particles of Co x S y , regular polygonal Co x S y or stacked tower Co x S y , which can all be used in the reaction of hydrogen sulfide and carbon dioxide hydrogenation to produce methyl mercaptan.

[0021] Furthermore, in the reaction, the raw gas contains 1% CO2, 4% H2S, 4% H2 and balance gas N2; the raw gas flow rate is 5 mL / min; the reaction pressure is 1.5 Mpa; and the reaction temperature is 200~360 ℃, preferably 280 ℃.

[0022] The present invention has the following advantages and beneficial effects:

[0023] 1. Co prepared by the present invention x S y The catalyst has abundant sulfur vacancies, which promote the adsorption of H2S and CO2 and enhance reaction activity. Furthermore, its raw materials are inexpensive and its preparation process is simple, which means it has broad application prospects.

[0024] 2. Co synthesized by the present invention x S y The catalyst has a higher specific surface area, which can expose more active sites. x S y The catalyst has good activity in the study of catalytic hydrogenation of H2S and CO2 to methyl mercaptan. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Co prepared in Examples 1 to 4 x S y X-ray powder diffraction spectrum of the catalyst.

[0026] Figure 2 Co prepared in Examples 1 to 4 x S y SEM images of the catalyst (A~D correspond to Co x S y -A~Co x S y -D).

[0027] Figure 3 Co prepared in Example 2 x S y -B catalyst transmission electron microscopy image.

[0028] Figure 4 Co prepared in Examples 1 to 4 x S y XPS spectrum of the catalyst.

[0029] Figure 5 Co prepared in Examples 1 to 4 x S y N2 adsorption-desorption isotherms of the catalyst.

[0030] Figure 6 Co prepared in Examples 1 to 4 x S y EPR spectrum of the catalyst.

[0031] Figure 7 Co prepared in Examples 1 to 4 x S y Comparison of the catalytic activity of the catalysts in the hydrogenation of H2S and CO2 to produce methyl mercaptan. DETAILED DESCRIPTION

[0032] A Co x S y The preparation method of the catalyst comprises the following steps:

[0033] 1) Add the cobalt source to the solvent, stir continuously for half an hour, then let it stand for 0-24 hours, or pour it into a hydrothermal reactor and react at 180°C for 2-5 hours to obtain the precursor;

[0034] 2) Mix the obtained precursor with the sulfur source and stir continuously for half an hour, then pour into a hydrothermal reactor and hydrothermally react at 120℃~180℃ for 8~24 hours;

[0035] 3) After the reaction, the hydrothermal autoclave was cooled to room temperature, and the precipitate was washed three times with deionized water and ethanol in turn, and then dried in a vacuum at 80 °C to obtain the Co x S y Catalyst; wherein x=an integer from 1 to 9, and y=an integer from 1 to 8.

[0036] Wherein, the cobalt source in step 1) is cobalt nitrate hexahydrate (Co(NO3)2·6H2O) or cobalt chloride hexahydrate (CoCl2·6H2O). The solvent is one or more of water, methanol, isopropanol and glycerol.

[0037] The sulfur source in step 2) is thiourea or thioacetamide.

[0038] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0039] Example 1 Petal-shaped Co x S y Catalyst preparation

[0040] Weigh 1 mmol of Co(NO3)2·6H2O and dissolve it in 70 mL of deionized water. Stir continuously at 50°C for half an hour. Add 6 mmol of thiourea while stirring. Then pour the mixed solution into a 100 mL hydrothermal reactor and react at 180°C for 12 hours. After the temperature of the hydrothermal reactor drops to room temperature, take out the precipitate, wash it three times with deionized water and ethanol in turn, and then dry it in a vacuum oven at 80°C. The final product is a petal-shaped mixed phase catalyst of CoS2 and CoS, recorded as Co x S y -A.

[0041] Example 2 Spherical Co particles x S y Catalyst preparation

[0042] Weigh 1 mmol of Co(NO3)2·6H2O and dissolve it in a mixed solution of 60 mL of isopropanol and 15 mL of glycerol, and stir it continuously for half an hour. Then pour the mixed solution into a 100 mL hydrothermal kettle and react at 180 °C for 3 hours. The resulting precipitate is washed three times with deionized water and ethanol in turn, and then dried in a vacuum oven at 80 °C to obtain a precursor. The obtained precursor is dissolved in 50 ml of deionized water, and 0.5 mmol of thiourea is added. After stirring for half an hour, the mixed solution is poured into a 100 mL hydrothermal kettle and reacted at 180 °C for 12 hours. After the temperature of the hydrothermal kettle drops to room temperature, take out the precipitate, wash it three times with deionized water and ethanol in turn, and then dry it in a vacuum oven at 80 °C. The final product is a spherical Co9S8 catalyst, recorded as Co x S y -B.

[0043] Example 3 Regular polygonal Co x S y Catalyst preparation

[0044] Weigh 2 mmol of Co(NO3)2·6H2O and dissolve it in 90 mL of anhydrous methanol. Weigh 1 mmol of 2-methylimidazole as a template and dissolve it in 30 mL of methanol solution. Then quickly pour the latter solution into the former solution, stir continuously for half an hour, and let the mixed solution stand at room temperature for 24 hours. Then centrifuge and wash the solution after standing to obtain a precursor. The obtained precursor is dissolved in 40 mL of anhydrous ethanol, 0.1 mol of thiourea is added and stirred continuously for half an hour. Then, the mixed solution is poured into a 100 mL hydrothermal reactor and reacted at 120 ° C for 4 hours. After the temperature of the hydrothermal reactor drops to room temperature, take out the precipitate, wash it three times with deionized water and ethanol in turn, and then dry it in a vacuum oven at 80 ° C. The final product is a regular polygonal Co3S4 catalyst, recorded as Co x S y -C.

[0045] Example 4 Stacked Tower Co x S y Catalyst preparation

[0046] 1 mmol of Co(NO3)2·6H2O was weighed and dissolved in 70 mL of deionized water and stirred at 50°C for half an hour. 6 mmol of thioacetamide was added while stirring. The mixed solution was then poured into a 100 mL hydrothermal reactor and reacted at 180°C for 12 hours. After the hydrothermal reactor temperature dropped to room temperature, the precipitate was taken out and washed three times with deionized water and ethanol in turn, and then dried in a vacuum oven at 80°C. The final product was a stacked tower-shaped CoS catalyst, recorded as Co x S y -D.

[0047] Preparation of Comparative Example MoS2 Catalyst

[0048] 3 mmol of ammonium molybdate tetrahydrate and 126 mmol of thiourea were dissolved in 120 mL of deionized water and stirred for 15 minutes. The mixture was then poured into a 100 mL hydrothermal reactor and reacted at 180°C for 12 hours. After the hydrothermal reactor cooled to room temperature, the precipitate was removed and washed three times with deionized water and then ethanol, then dried in a vacuum oven at 80°C to obtain the MoS2 catalyst.

[0049] X-ray powder diffraction (XRD): The phase characterization of the samples was carried out using an X'pert pro powder diffractometer from Panalytical Company. The detector was an X'celerator, the copper target (Cu Kα, λ = 0.154 nm) was used as the excitation radiation source, the operating voltage was 45 KV, and the operating current was 40 mA.

[0050] The morphology of the catalyst was observed by S-4800 field emission scanning electron microscope. The vacuum degree of the analysis chamber was less than 2.7×10 –6 Pa, the scanning voltage and current were 5 kV and 7 μA respectively. The sample powder was stuck on the conductive glue and sprayed with gold before observation.

[0051] Field emission transmission electron microscopy (TEM): TEM images of the samples were observed on a Tecnai G2 F20 transmission electron microscope (TEM) with an accelerating voltage of 200 kV.

[0052] X-ray Photoelectron Spectroscopy (XPS): The elemental chemical state of the sample surface was characterized using an ESCACAB 250xi X-ray Photoelectron Spectrometer, using a monochromated A1 Kα excitation source (1486.6 eV, 15 kV, 10.8 mA). The sample was first pressed and fixed on ultra-high vacuum insulating tape, which was then affixed to the sample holder. Before entering the analysis chamber, the sample chamber and sample preparation chamber were gradually drawn to a specified vacuum level. The vacuum level in the analysis chamber was less than 10 -8 The obtained spectrum was calibrated using C1s = 284.8 eV as the internal standard.

[0053] The specific surface area of ​​the samples was determined by N2 physical adsorption using a fully automatic surface area analyzer (MicrometricASAP2020). The test conditions were as follows: 0.1 g of sample was weighed, pretreated at 200°C for 120 minutes, and then analyzed at liquid nitrogen temperature. The specific surface area of ​​the samples was calculated using the BJH method.

[0054] Defect information on the sample can be obtained using an E-500 electron paramagnetic resonance spectrometer (Bruker). Testing is performed at -150°C and a frequency of 100 kHz. After the sample is placed in a quartz tube, the tube must be kept upright, and the instrument's operating environment must be stable and well-ventilated.

[0055] Figure 1 Co prepared in Examples 1 to 4 of the present invention x S y X-ray powder diffraction spectrum of the catalyst. As can be seen from the figure, the sample Co x S y -A's diffraction peaks are attributed to CoS2 (JCPDS 89-1492) and CoS (JCPDS 75-0605); x S y -B diffraction peaks are attributed to Co9S8 (JCPDS 73-1442); sample Co x Sy -C diffraction peaks are attributed to Co3S4 (JCPDS 42-1448); sample Co x S y The diffraction peak of -D is assigned to CoS (JCPDS 75-0605).

[0056] Figure 2 Co prepared in Examples 1 to 4 x S y SEM image of the catalyst. As can be seen from the figure, Co x S y -A is a petal-like morphology composed of 200nm nanosheets, with a petal diameter of about 7 μm (A). x S y -B is composed of 70 nm nanoparticles with a spherical morphology, and the diameter of the spherical particles is about 4 μm (B). x S y -C is a regular cubic morphology with a side length of 400 nm (C). x S y -D is a tower-like morphological feature composed of irregular polygons (D).

[0057] Figure 3 The spherical Co particles prepared in Example 2 x S y TEM image of the -B catalyst. As can be seen from the figure, it is composed of solid small particles, in which the lattice fringes correspond to the XRD and the (311) crystal plane of Co9S8 can be seen.

[0058] Figure 4 Co prepared in Examples 1 to 4 x S y XPS spectrum of the catalyst. As can be seen from the figure, the peak positions of the four samples are 778.4 eV, 793.4 eV, 781.7 eV, 798.1 eV, 786.2 eV, and 802 eV, which are respectively attributed to Co 3+ 、Co 2+ and satellite peaks. By comparing the peak intensities, it was found that Co 2+ / Co 3+ The values ​​from large to small are Co x S y -B>Co x S y -C>Co x S y -D>Co x S y -A. Since it is known that Co 2+ / Co3+ The ratio is positively correlated with the activity, and its active site is Co 2+ , therefore, more Co 2+ It can promote the adsorption and further conversion of H2S and CO2.

[0059] Figure 5 Co prepared in Examples 1 to 4 x S y The physical adsorption and desorption results of the catalyst. As can be seen from the figure, the specific surface areas of the catalysts prepared in Examples 1 to 4 are 8.9 m 2 / g, 28.2m 2 / g、70.4m 2 / g, 14.1 m 2 / g, of which Co x S y -B has a large specific surface area, which can fully expose its active sites and is conducive to the catalytic reaction.

[0060] Figure 6 Co prepared in Examples 1 to 4 x S y EPR spectrum of the catalyst. As can be seen from the figure, the catalyst Co x S y The presence of a peak at g = 2.003 indicates that the catalyst containing sulfur vacancies was successfully synthesized. The presence of sulfur vacancies can improve the reaction activity.

[0061] Performance test of hydrogen sulfide and carbon dioxide hydrogenation to produce methyl mercaptan:

[0062] The catalysts prepared in Examples 1-4 and the comparative example were ground into powders for activity evaluation in the hydrogenation of H2S and CO2 to methyl mercaptan. The test conditions were as follows: 1 g catalyst; feed gas consisting of 1% CO2, 4% H2S, 4% H2, and the balance N2; pretreatment at 200°C with a flow rate of 30 mL / min; reaction at a feed gas flow rate of 5 mL / min; reaction pressure of 1.5 MPa; analysis using a GC-9790Plus gas chromatograph; and reaction temperature between 200°C and 360°C.

[0063] Figure 7 The figure shows the catalytic activity comparison of Examples 1 to 4 in the production of methyl mercaptan by hydrogenation of H2S and CO2. As can be seen from the figure, the CO2 conversion rate and CH3SH yield of the catalysts are Co x S y -B>Co x S y -C>Co x S y -D>Co xS y -A. Co x S y -B has a high catalytic activity because it can produce more sulfur vacancies and has a higher specific surface area, exposing more active sites, promoting the reaction and improving the reaction activity.

[0064] Table 1 is the Co prepared in Examples 1 to 4 x S y The catalytic activity results of the MoS2 catalyst prepared in the comparative example in the hydrogenation of H2S and CO2 to produce methyl mercaptan. x S y -B has significantly improved activity compared with the control.

[0065] Table 1 Catalytic activity of Examples 1 to 4 and Comparative Example samples at 280°C

[0066]

[0067] In summary, the four different morphologies of Co prepared by the present invention x S y The catalysts have different catalytic performances in the hydrogenation of H2S and CO2 to produce methyl mercaptan. x S y -B sample has the highest catalytic activity and has great application potential.

[0068] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A Co x S y The application of the catalyst is characterized by: Co x S y The catalyst is used in the reaction of hydrogen sulfide and carbon dioxide hydrogenation to produce methyl mercaptan; The Co x S y The preparation of the catalyst comprises the following steps: 1) Add the cobalt source to the solvent, continue stirring for half an hour, and then allow to stand or perform solvent thermal treatment to obtain a precursor; 2) Mixing the obtained precursor with a sulfur source and stirring continuously for half an hour, and then performing a hydrothermal reaction; 3) After the reaction temperature is cooled to room temperature, the obtained precipitate is filtered, washed, and dried to obtain the product.

2. A Co according to claim 1 x S y The application of the catalyst is characterized by: The cobalt source in step 1) is cobalt nitrate hexahydrate or cobalt chloride hexahydrate.

3. A Co according to claim 1 x S y The application of the catalyst is characterized by: The solvent in step 1) is one or more of water, methanol, isopropanol and glycerol.

4. A Co according to claim 1 x S y The application of the catalyst is characterized by: In step 1), the standing time is 0 to 24 hours; the solvothermal reaction is carried out at a temperature of 180° C. for 2 to 5 hours.

5. A Co according to claim 1 x S y The application of the catalyst is characterized by: In step 1), a template agent 2-methylimidazole is also added.

6. A Co according to claim 1 x S y The application of the catalyst is characterized by: The sulfur source in step 2) is thiourea or thioacetamide.

7. A Co according to claim 1 x S y The application of the catalyst is characterized by: The temperature of the hydrothermal reaction in step 2) is 120°C to 180°C, and the time is 8 to 24 hours.

8. A Co according to claim 1 x S y The use of a catalyst is characterized in that The catalyst obtained is a petal-shaped Co x S y , spherical particles of Co x S y , regular polygonal Co x S y or stacked tower Co x S y , where x is an integer from 1 to 9, and y is an integer from 1 to 8.

9. A Co according to claim 1 x S y The application of the catalyst is characterized by: The raw gas contains 1% CO2, 4% H2S, 4% H2 and balance gas N2; the raw gas flow rate is 5 mL / min; the reaction pressure is 1.5 MPa; and the reaction temperature is 200~360℃.

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