Use of an amine-modified molybdenum-based catalyst in the synthesis of methyl mercaptan and ethyl mercaptan

Abstract

The application discloses application of an amine group modified molybdenum-based catalyst in synthesis of methyl mercaptan and ethyl mercaptan, wherein the amine group modified molybdenum-based catalyst is prepared by the following steps: soaking alumina in amine liquid at 60-120 DEG C, solid-liquid separation, washing and vacuum drying of the solid, calcination under an inert atmosphere to obtain an Al2O3-N carrier, then soaking the Al2O3-N carrier in a molybdate solution, solid-liquid separation, vacuum drying of the solid, calcination under an inert atmosphere, grinding and sieving, and high-temperature sulfuration treatment in a mixed atmosphere of H2 and H2S; the catalyst is used for synthesizing methyl mercaptan from CO2 / H2 / H2S as raw materials, and is used for synthesizing ethyl mercaptan from C2H4 / H2S as raw materials, and has high product selectivity and stability, and can realize environmental benefits and economic benefits of carbon-sulfur synergistic resource utilization.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis, and particularly relates to a method for synthesizing methyl mercaptan and ethyl mercaptan by using an amine group modified molybdenum-based catalyst. BACKGROUND

[0002] Methyl mercaptan (CH3SH) is an important chemical intermediate, which is often used in agriculture, petroleum chemical industry and synthesis of methionine (an essential amino acid for humans and animals). Ethyl mercaptan (C2H6S) is an important chemical intermediate for producing pesticides, herbicides and medicines. Since the amount of methyl / ethyl mercaptan required by the market is rapidly increasing, it is necessary to develop an efficient and environmentally friendly process to produce methyl / ethyl mercaptan.

[0003] H2S is a typical malodorous pollutant, which seriously affects environmental quality. The treatment of H2S mainly adopts solution absorption method and Claus method, but there are still difficulties such as corrosion of equipment or secondary environmental pollution. The one-step synthesis of methyl mercaptan from CO2 / H2 / H2S is an ideal way to turn waste into treasure, and the catalytic synthesis of ethyl mercaptan from H2S and ethylene also provides a new idea for the resource utilization of H2S. In the current research, the synthesis strategy of methyl / ethyl mercaptan generally has the problems of low yield and low selectivity, which restricts the further development of the resource utilization of mercaptan synthesis. Therefore, how to improve the yield and selectivity of methyl / ethyl mercaptan in the carbon-sulfur collaborative resource utilization strategy is a major challenge. SUMMARY

[0004] The application provides a method for synthesizing methyl mercaptan and ethyl mercaptan by using an amine group modified molybdenum-based catalyst. The method first soaks an alumina carrier in an amine solution, separates the solid and liquid, washes the solid, vacuum dries the solid, and calcines the solid under an inert atmosphere to obtain an Al2O3-N carrier. The Al2O3-N carrier is fully immersed in a molybdate solution by using an equal-volume impregnation method, the solid and liquid are separated, the solid is vacuum dried, the solid is calcined under an inert atmosphere, the solid is ground and sieved, and the solid is sulfided at high temperature under a mixed atmosphere of H2 and H2S to obtain an amine group modified molybdenum-based catalyst MoS2 / Al2O3-N. The MoS2 / Al2O3-N catalyst is applied to the one-step synthesis of methyl mercaptan from CO2 / H2 / H2S and the synthesis of ethyl mercaptan from C2H4 / H2S to realize the collaborative resource utilization of carbon and sulfur.

[0005] The mass-volume ratio g:mL of the alumina carrier to the amine solution is 1:25-1:35, the soaking temperature is 60-120℃, the soaking time is 4-10h, the vacuum drying temperature is 80-140℃, the inert atmosphere includes N2, He and Ar, the calcination temperature is 400-700℃, the calcination time is 5-7h, and the amine solution includes but is not limited to ethanolamine (including monoethanolamine and diethanolamine), ethylenediamine and ammonia water.

[0006] The amine group in the amine can be adsorbed on the surface of the alumina carrier, and after calcination in an inert atmosphere, the amine group can interact with Al to form an Al-N bond; in addition, the amine group can replace part of the oxygen atoms to form a stable N-O bond; due to the introduction of an additional nitrogen molecule, Mo monomers can be anchored, thereby improving the dispersion of Mo active species.

[0007] The molybdate includes, but is not limited to, sodium molybdate, ammonium molybdate, magnesium molybdate, and zinc molybdate; the loading amount of Mo is 2%-10%.

[0008] The drying temperature after impregnation of the Al2O3-N carrier is 80-140 DEG C, and the time is 4-8h; the calcination temperature is 400-700 DEG C, and the time is 2-6h; the sieving refers to passing through a 20-100 mesh sieve.

[0009] The volume ratio of H2 to H2S in the mixed atmosphere of H2 and H2S is 1-9:1-9; the flow rate of the mixed atmosphere of H2 and H2S is 10-100 mL / min; the heating rate is 1-10 DEG C / min, the sulfidation temperature is 200-400 DEG C; and the sulfidation time is 2-5h.

[0010] The application of the amine group modified molybdenum-based catalyst MoS2 / Al2O3-N to the one-step synthesis of CH3SH from CO2 / H2 / H2S is to synthesize CH3SH from CO2, H2 and H2S under the catalysis of the MoS2 / Al2O3-N catalyst and at a temperature of 200-700 DEG C, wherein the mass concentration of CO2 in the gas containing CO2, H2 and H2S is 100000-700000 ppm, the mass concentration of H2 is 100000-700000 ppm, the mass concentration of H2S is 100000-700000 ppm, the total space velocity of the feed is 1000-10000 h -1 , the total flow rate is 30-100 mL / min, and the reaction pressure is 0-2 MPa.

[0011] The application of the amine group modified molybdenum-based catalyst MoS2 / Al2O3-N to the synthesis of ethyl mercaptan from C2H4 / H2S is to synthesize ethyl mercaptan from C2H4 and H2S under the catalysis of the MoS2 / Al2O3-N catalyst and at a temperature of 100-600 DEG C, wherein the mass concentration of C2H4 in the gas containing C2H4 and H2S is 100000-700000 ppm, the mass concentration of H2S is 100000-700000 ppm, the total space velocity of the feed is 100-500 h -1 , the total flow rate is 30-100 mL / min, and the reaction pressure is 0-2 MPa.

[0012] The beneficial technical effects of the present application are as follows:

[0013] The application introduces nitrogen molecules into the Al2O3 carrier by carrier etching method, anchors Mo atoms by the nitrogen molecules, and obtains the MoS2 / Al2O3-N catalyst after sulfuration, so that the yield and selectivity of methyl mercaptan and ethyl mercaptan are much higher than those of the existing catalysts.

[0014] The preparation method of the MoS2 / Al2O3-N catalyst is simple, the running cycle is stable, and the catalyst is suitable for industrial production and market promotion and application. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The CO2 catalytic conversion rate results of different catalysts in Example 1 are shown in Table 1.

[0016] Figure 2 The CH3SH yield results in Example 1 are shown in Table 2. DETAILED DESCRIPTION

[0017] In order to better understand the technical solutions of the application, the following examples will further illustrate the method provided by the application, but the application is not limited to the listed examples, and any known changes within the scope of the claims of the application should also be included; in the examples, the catalytic reaction uses a fixed bed reactor, and the analysis instrument includes a gas chromatograph, a gas chromatographic column, an FID detector, a TCD detector and an FPD detector. Example 1

[0018] 1. 5 g of alumina was dispersed in 150 mL of ethylenediamine, soaked at 80℃ for 6 h, centrifuged, and the solid was washed with water and anhydrous ethanol three times, then vacuum dried at 80℃ for 12 h, calcined at 550℃ under nitrogen atmosphere for 6 h, to obtain an Al2O3-N carrier;

[0019] 2. Mo source was loaded on the Al2O3-N carrier by equal volume impregnation method, and the Mo loading amount was 10%, 0.5772 g of ammonium molybdate was dissolved in 4.5 mL of deionized water, then 3 g of Al2O3-N carrier was added, and after uniform stirring, ultrasonic treatment was performed for 10 min, and the mixture was placed at room temperature for 12 h, vacuum dried at 110℃ for 6 h, and then calcined at 550℃ under nitrogen atmosphere for 6 h (the heating rate was 5℃ / min), ground through a 40-60 mesh sieve, and 0.8 g of the sieved material was placed in a fixed bed reactor, and a mixed gas of H2 and H2S (volume ratio 9:1) was introduced at a total flow rate of 40 mL / min, and the temperature was increased to 400℃ at a rate of 2℃ / min and maintained for 2 h, to obtain a MoS2 / Al2O3-N catalyst;

[0020] Meanwhile, the alumina was calcined at 550℃ under air atmosphere for 6 h, and then Mo source was loaded on the calcined alumina carrier by equal volume impregnation method (the loading conditions were the same as step 2), to obtain a MoS2 / Al2O3 catalyst as a control.

[0021] 3. 0.4 g of MoS2 / Al2O3-N catalyst was charged into a tubular furnace reactor, and a mixed gas containing CO2, H2, and H2S was introduced, wherein the mass concentration of CO2 was 100,000 ppm, the mass concentration of H2 was 400,000 ppm, the mass concentration of H2S was 500,000 ppm, and the total space velocity of the feed was 3000 h⁻¹. -1 The reaction system pressure was 0.2 MPa, the reaction temperature range was 250-500℃, and the CO2 / H2 / H2S one-step synthesis of methanethiol was carried out. At the same time, the MoS2 / Al2O3 catalyst was used to prepare methanethiol under the same conditions.

[0022] See results Figure 1 , 2 As can be seen from the figure, the conversion rate of CO2 by the MoS2 / Al2O3-N catalyst is higher than that of the MoS2 / Al2O3 catalyst. Furthermore, at 350-400℃, the yield and selectivity of CH3SH produced by the MoS2 / Al2O3-N catalyst are significantly improved, indicating that nitrogen molecule treatment improves the catalytic performance of the prepared catalyst. Example 2

[0023] 1. Place 3g of alumina support in 100mL of ethylenediamine, stir at 80℃ for 6h, centrifuge, wash the solid three times each with deionized water and anhydrous ethanol, dry in vacuum at 100℃ for 8h, and calcine at 550℃ for 6h under nitrogen atmosphere to obtain Al2O3-N support.

[0024] 2. Mo source was loaded onto Al2O3-N support using an equal-volume impregnation method with a Mo loading of 10%. 0.5772 g of ammonium molybdate was dissolved in 4.5 mL of deionized water, and then 3 g of Al2O3-N support was added. After thorough stirring, the mixture was ultrasonically treated for 10 min, allowed to stand at room temperature for 12 h, and vacuum dried at 110 °C for 6 h. The mixture was then calcined at 550 °C for 6 h under a nitrogen atmosphere (heating rate 5 °C / min). The mixture was ground through a 40-60 mesh sieve, and 0.8 g of the sieved material was placed in a fixed-bed reactor. A mixture of H2 and H2S gas (volume ratio 9:1) was introduced at a total flow rate of 40 mL / min. The temperature was increased to 400 °C at a programmed rate of 2 °C / min and held for 2 h to obtain the MoS2 / Al2O3-N catalyst.

[0025] 3. 0.4 g of MoS2 / Al2O3-N catalyst was charged into a tubular furnace reactor, and a mixed reaction gas containing C2H4 and H2S was introduced, wherein the mass concentration of C2H4 was 100,000 ppm and the mass concentration of H2S was 300,000 ppm, and the total space velocity of the feed was 300 h⁻¹. -1The C2H4 / H2S catalytic synthesis of C2H6S was carried out at a reaction system pressure of 1.8 MPa and a reaction temperature range of 160-360 °C. The conversion rate of C2H4 was 81.3% and the selectivity of C2H6S was about 91% at 240 °C.

[0026] The good catalytic performance of the MoS2 / Al2O3-N catalyst is attributed to the unsaturated N molecules formed after the treatment of the alumina carrier by nitrogen molecules, which can anchor Mo atoms and promote the dispersion of active species. The Mo species on the surface of the MoS2 / Al2O3 catalyst exist in the form of clusters or nanoparticles. Therefore, the higher atomic utilization rate provides the MoS2 / Al2O3-N catalyst with superior catalytic performance, which not only solves the problem of resource utilization of greenhouse gas CO2 and malodorous gas H2S, but also provides a new strategy for the synthesis of methyl / ethyl mercaptan.

Claims

1. The application of an amine-modified molybdenum-based catalyst in the synthesis of methanethiol and ethanethiol, characterized in that: The amine-modified molybdenum-based catalyst is prepared by immersing alumina in an amine solution at 60-120°C, separating the solid and liquid, washing and vacuum drying the solid, and calcining it under an inert atmosphere to obtain an Al2O3-N support. Then, the Al2O3-N support is fully impregnated in a molybdate solution, separated from the solid and liquid, vacuum dried the solid, calcined under an inert atmosphere, ground and sieved, and then subjected to high-temperature sulfidation treatment in a mixed atmosphere of H2 and H2S.

2. The application according to claim 1, characterized in that: The amines in the amine solution include ethanolamine, ethylenediamine, and ammonia. The mass-to-volume ratio of alumina to amine solution (g:mL) is 1:25-1:

35. The molybdates include sodium molybdate, ammonium molybdate, magnesium molybdate, and zinc molybdate. The Mo loading is 2%-10%.

3. The application according to claim 1, characterized in that: The calcination temperature is 400-700℃.

4. The application according to claim 1, characterized in that: In a mixed atmosphere of H2 and H2S, the volume ratio of H2 to H2S is 1-9:1-9, the high-temperature vulcanization temperature is 200-400℃, and the vulcanization time is 2-5h.

5. The application according to claim 1, characterized in that: Methanethiol was synthesized from a gas containing CO2, H2, and H2S at 200-700℃ using an amino-modified molybdenum-based catalyst. The mass concentrations of CO2, H2, and H2S in the gas were 100,000-700,000 ppm, H2, and H2S, respectively, and the total space velocity of the feed was 1,000-10,000 h⁻¹. -1 The total flow rate is 30-100 mL / min, and the reaction pressure is 0-2 MPa.

6. The application according to claim 1, characterized in that: Ethyl mercaptan was synthesized from a gas containing C2H4 and H2S at 100-600℃ using an amine-modified molybdenum-based catalyst. The C2H4 mass concentration in the gas was 100,000-700,000 ppm, and the H2S mass concentration was 100,000-700,000 ppm. The total space velocity of the feed was 100-500 h⁻¹. -1 The total flow rate is 30-100 mL / min, and the reaction pressure is 0-2 MPa.

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