Use of a core-shell type K x -MoO3@SiO2 catalyst for synthesizing methanethiol or ethanethiol

Abstract

The present invention discloses the use of a core-shell K x -MoO3@SiO2 catalyst in the synthesis of methanethiol or ethanethiol. The core-shell K x -MoO3@SiO2 catalyst is prepared by placing molybdate in an ethanol solution of polyvinylpyrrolidone, stirring and mixing evenly, reacting at 150-240 °C, separating solid and liquid, washing and drying the solid to obtain MoO2; placing MoO2 in an ethanol solution, ultrasonically dispersing it, adding diethanolamine and cetyltrimethylammonium bromide to the dispersion under stirring at room temperature, then dropping tetraethyl orthosilicate, continuing to stir, separating solid and liquid, washing and drying the solid and then calcining to obtain the core-shell MoO3@SiO2 material; adding the core-shell MoO3@SiO2 material to a potassium precursor solution, mixing evenly, ultrasonically treating, standing overnight, drying and calcining to obtain the catalyst. The above catalyst has the advantages of excellent catalyst activity, high product selectivity and low reaction energy consumption in the preparation of methanethiol and ethanethiol.

Description

Technical Field

[0001] The present invention relates to a preparation method of a K x -MoO3@SiO2 mesoporous core-shell catalyst and its application in the catalytic synthesis of methanethiol (CH3SH) and ethanethiol (C2H5SH) from a CO / H2S / H2 gas mixture or a C2H4 / H2S gas mixture, belonging to the technical field of the preparation of methanethiol and ethanethiol. Background Art

[0002] Methanethiol (CH3SH) is an important chemical intermediate and industrial raw material, which can be used to produce high-value organic sulfur compounds such as methionine, dimethyl disulfide, methanesulfonic acid, etc. Synthesizing CH3SH from high-sulfur syngas (CO / H2S / H2) as a raw material can effectively avoid the resource waste and excessive environmental pollution caused by the traditional method of synthesizing CH3SH from methanol and hydrogen sulfide, and has attracted the interest of many scholars. The commonly used catalyst for synthesizing CH3SH from high-sulfur syngas (CO / H2S / H2) is a MoS2 catalyst supported on a γ-Al2O3 or silica (SiO2) carrier. Although this catalyst has received extensive attention in the field of CH3SH synthesis, the low CO conversion rate and CH3SH selectivity during the CH3SH synthesis process have always been unavoidable problems, which result in a low yield of CH3SH produced by this method, far from meeting the requirements of industrial production.

[0003] In addition, ethanethiol (C2H5SH) is also an important chemical intermediate and industrial raw material, which is widely used in the synthesis of pesticides and pharmaceuticals, etc.; it can also be used as a molecular weight regulator and chain transfer agent during the polymerization of high molecular polymers; in addition, ethanethiol has a stench and can be used as an odorant for gas, as a warning agent to prevent accidents such as fires and explosions caused by leakage. Currently, most domestic city gas uses ethanethiol as an odorant. Among the many preparation methods of ethanethiol, the ethylene sulfidation method has received increasing attention as an atom-economic route. Currently, the commonly used catalyst for preparing C2H5SH by the ethylene sulfidation method is a cobalt-modified molybdenum oxide-based catalyst. However, the performance of this catalyst is also far from meeting the requirements of industrial application. Similar to the synthesis of CH3SH, the lack of a high-performance catalyst during the C2H5SH synthesis process is also an important factor restricting the efficient synthesis of C2H5SH by the ethylene sulfidation method. Summary of the Invention

[0004] The present invention provides a new use of a core-shell K x -MoO3@SiO2 catalyst, that is, its application in the synthesis of methanethiol or ethanethiol, which can simultaneously realize the catalytic synthesis of methanethiol and ethanethiol.

[0005] The core-shell K xThe preparation of the -MoO3@SiO2 catalyst is as follows:

[0006] 1. Place the molybdate in an ethanol solution of polyvinylpyrrolidone (PVP). After stirring and mixing evenly, react at 150 - 240 °C for 15 - 24 h, perform solid-liquid separation, and wash and dry the solid to obtain MoO2;

[0007] The mass ratio of the molybdate to polyvinylpyrrolidone is 1:2 - 5, and the volume concentration of the ethanol solution in the ethanol solution of polyvinylpyrrolidone is 15 - 40%;

[0008] 2. Place 10 - 50 mg of MoO2 in an ethanol solution with a volume concentration of 15 - 40%. After ultrasonic dispersion, add 0.2 - 1 mL of diethanolamine and 0.5 - 3 g of cetyltrimethylammonium bromide to the dispersion under room temperature and stirring. Then, dropwise add 0.2 - 1.6 mL of tetraethyl orthosilicate, and continue stirring for 10 - 30 h. Perform solid-liquid separation, wash and dry the solid, and then calcine to obtain the core-shell type MoO3@SiO2 material; Add the core-shell type MoO3@SiO2 material to the potassium precursor solution, mix evenly, perform ultrasonic treatment, let it stand overnight, dry and calcine to obtain the core-shell type Kx-MoO3@SiO2 catalyst;

[0009] One of potassium carbonate, potassium sulfide, and potassium sulfate, the molar ratio of K:Mo is 0.5 - 3:1; The calcination temperature is 450 - 650 °C for 2 - 8 h.

[0010] The core-shell type K x -MoO3@SiO2 catalyst in the synthesis of methanethiol uses a mixed gas of CO, H2, and H2S as raw materials, where the concentration of CO is 100000 - 200000 ppm, the concentration of H2 is 200000 - 500000 ppm, and the concentration of H2S is 200000 - 800000 ppm. Methanethiol is synthesized at 0 - 0.2 MPa and 200 - 550 °C, and the space velocity of the reaction gas is 1000 - 10000 h -1 .

[0011] In the method for synthesizing ethanethiol, a mixed gas of C2H4 and H2S is used as raw materials, where the concentration of C2H4 is 100000 - 400000 ppm, and the concentration of H2S is 300000 - 800000 ppm. Ethanethiol is synthesized at 0 - 2 MPa and 100 - 400 °C, and the space velocity of the reaction gas is 1000 - 10000 h -1 .

[0012] Advantages and technical effects of the method of the present invention:

[0013] (1) The present invention uses a potassium-doped mesoporous core-shell type K xThe synthesis of low - molecular - weight thiols catalyzed by the -MoO3@SiO2 catalyst not only shows excellent performance in the synthesis of methanethiol, but also has remarkable effects in the synthesis of ethanethiol. It has good reaction activity and high selectivity for the target product, demonstrating excellent catalytic performance and showing its universality in the synthesis of low - molecular - weight thiols.

[0014] (2) The mesoporous core - shell K x The synthesis method of the -MoO3@SiO2 catalyst of the present invention is simple, with excellent catalytic performance, which is conducive to promotion and large - scale application. Brief Description of the Drawings

[0015] Figure 1 It is the transmission electron microscope image of the core - shell K x -MoO3@SiO2 catalyst prepared in Example 2. Detailed Description of the Embodiments

[0016] The present invention will be further described in detail below through examples. However, the protection scope of the present invention is not limited to the content described. In the examples, the methods are conventional methods unless otherwise specified, and the reagents are conventional reagents or reagents prepared according to conventional methods unless otherwise specified.

[0017] Example 1: Preparation and Application of MoO3@SiO2 Catalyst without Potassium Doping

[0018] 1. Place 150 mg of ammonium molybdate in 32 mL of an ethanol solution of polyvinylpyrrolidone (31% ethanol solution containing 400 mg of PVP). After stirring for 1 h, transfer the mixture to a polytetrafluoroethylene reaction kettle and react at 200 °C for 20 h. Centrifuge, wash the solid with a mixed solution of ethanol and acetone (volume ratio 1:1), and dry at 100 °C to obtain MoO2. Place 30 mg of MoO2 in 53 mL of an ethanol solution with a volume concentration of 37%. After ultrasonic treatment for 1 h, add 0.2 mL of diethanolamine and 0.73 g of cetyltrimethylammonium bromide to the dispersion under room temperature and stirring. Then, dropwise add 0.4 mL of tetraethyl orthosilicate and continue stirring for 24 h. Centrifuge, wash the solid with a mixed solution of ethanol and acetone, dry at 100 °C, and then calcine at 550 °C for 6 h to obtain the MoO3@SiO2 catalyst.

[0019] 2. After grinding and sieving the MoO3@SiO2 catalyst prepared by the above method to 40 - 60 mesh, take 0.4 g and load it into a tubular furnace reactor. Pass a CO / H2 / H2S mixed gas (the molar concentration of CO in the mixed gas is 100000 ppm, the molar concentration of H2 in the mixed gas is 400000 ppm, and the molar concentration of H2S in the mixed gas is 500000 ppm) and react at 0.2 MPa and 400 °C to synthesize CH3SH. The total gas feed space velocity is 3000 h -1, the CO conversion rate was 30%, and the CH3SH selectivity was 7%;

[0020] After grinding and sieving the MoO3@SiO2 catalyst prepared by the above method to 40-60 mesh, 0.4 g was taken and loaded into a tubular furnace reactor, and a C2H4 / H2S mixed gas (the molar concentration of C2H4 in the mixed gas was 250,000 ppm, and the molar concentration of H2S in the mixed gas was 750,000 ppm) was introduced to synthesize C2H5SH at 1.6 MPa and 240 °C. The total gas feed space velocity was 3000 h -1 , the C2H4 conversion rate was 42%, and the C2H5SH selectivity was 12%.

[0021] Example 2: Preparation and application of the core-shell K2-MoO3@SiO2 catalyst of the present invention

[0022] 1. Place 150 mg of ammonium molybdate in 32 mL of an ethanol solution of polyvinylpyrrolidone (31% ethanol solution containing 400 mg of PVP). After stirring for 1 h, transfer the mixture to a polytetrafluoroethylene reaction kettle and react at 200 °C for 20 h. Centrifuge, and wash the solid with a mixed solution of ethanol and acetone. Dry at 100 °C to obtain MoO2; place 30 mg of MoO2 in 53 mL of an ethanol solution with a volume concentration of 37%. After ultrasonic treatment for 1 h, add 0.2 mL of diethanolamine and 0.73 g of cetyltrimethylammonium bromide to the dispersion under room temperature and stirring. Then, dropwise add 0.4 mL of tetraethyl orthosilicate, and continue stirring for 24 h. Centrifuge, and wash the solid with a mixed solution of ethanol and acetone (1:1). After drying at 100 °C, calcine at 550 °C for 6 h to obtain the MoO3@SiO2 catalyst; add the core-shell MoO3@SiO2 material to a potassium carbonate solution with a K:Mo molar ratio of 2. After stirring evenly, perform ultrasonic treatment for 10 min, let it stand overnight, dry at 100 °C, and calcine at 550 °C for 6 h to obtain the core-shell K2-MoO3@SiO2 catalyst. Its transmission electron microscope image is shown in Figure 1 .

[0023] At the same time, a control catalyst was prepared by the impregnation method. Specifically, according to the ratio of K:Mo molar ratio of 2, potassium carbonate and ammonium molybdate were dissolved in 8 mL of deionized water (the theoretical loading amount of MoO3 on the microsilica spheres was the same as the mass percentage of MoO3 in MoO3@SiO2), and then 2 g of microsilica spheres were added. After stirring evenly, perform ultrasonic treatment for 10 min, let it stand overnight, dry at 100 °C, and calcine at 550 °C for 6 h to obtain the control catalyst;

[0024] 2. After grinding and sieving the core-shell K₂-MoO₃@SiO₂ catalyst and the control catalyst prepared in step 1 to 40-60 mesh, 0.4 g of each was taken and loaded into a tubular furnace reactor. A CO / H₂ / H₂S mixed gas (the molar concentration of CO in the mixed gas was 100,000 ppm, the molar concentration of H₂ in the mixed gas was 400,000 ppm, and the molar concentration of H₂S in the mixed gas was 500,000 ppm) was introduced, and CH₃SH was synthesized by reaction at 0.2 MPa and 400 °C. The total gas feed space velocity was 3000 h -1 ; The conversion rate of CO by the core-shell K₂-MoO₃@SiO₂ catalyst was 63%, and the selectivity for CH₃SH was 79%; The conversion rate of CO by the control catalyst was 38%, and the selectivity for CH₃SH was 52%;

[0025] After grinding and sieving the core-shell K₂-MoO₃@SiO₂ catalyst and the control catalyst prepared in step 1 to 40-60 mesh, 0.4 g of each was taken and loaded into a tubular furnace reactor. A C₂H₄ / H₂S mixed gas (the molar concentration of C₂H₄ in the mixed gas was 250,000 ppm, and the molar concentration of H₂S in the mixed gas was 750,000 ppm) was introduced, and C₂H₅SH was synthesized at 1.6 MPa and 240 °C. The total gas feed space velocity was 3000 h -1 , The conversion rate of C₂H₄ by the core-shell K₂-MoO₃@SiO₂ catalyst was 85%, and the selectivity for C₂H₅SH was 96%; The conversion rate of C₂H₄ by the control catalyst was 62%, and the selectivity for C₂H₅SH was 78%.

[0026] Example 3: Preparation and application of the core-shell K 0.5 -MoO₃@SiO₂ catalyst of the present invention

[0027] 1. The preparation method of the core-shell K 0.5 -MoO₃@SiO₂ catalyst was the same as step 1 of Example 2, except that the K:Mo molar ratio was 0.5;

[0028] At the same time, a control catalyst was prepared by the impregnation method with a K:Mo molar ratio of 0.5, and the method was the same as Example 2;

[0029] 2. The core-shell K 0.5 -MoO₃@SiO₂ catalyst and the control catalyst were applied in the catalytic synthesis of methanethiol. The synthesis conditions were the same as in Example 2. As a result, the conversion rate of CO by the core-shell K 0.5 -MoO₃@SiO₂ catalyst was 41%, and the selectivity for CH₃SH was 25%; The conversion rate of CO by the control catalyst was 27%, and the selectivity for CH₃SH was 15%;

[0030] The core-shell K 0.5The K1-MoO3@SiO2 catalyst and the control catalyst were applied in the synthesis of ethanethiol. The synthesis conditions were the same as those in Example 2. As a result, for the core-shell K1-MoO3@SiO2 catalyst, the conversion rate of C2H4 was 52%, and the selectivity for C2H5SH was 31%. For the control catalyst, the conversion rate of C2H4 was 33%, and the selectivity for C2H5SH was 16%. 0.5 For the K1-MoO3@SiO2 catalyst, the conversion rate of C2H4 was 52%, and the selectivity for C2H5SH was 31%. For the control catalyst, the conversion rate of C2H4 was 33%, and the selectivity for C2H5SH was 16%.

[0031] Example 4: Preparation and application of the core-shell K1-MoO3@SiO2 catalyst of the present invention

[0032] 1. The preparation method of the core-shell K1-MoO3@SiO2 catalyst was the same as that in Step 1 of Example 2, except that the molar ratio of K:Mo was 1. At the same time, a control catalyst was prepared by the impregnation method with a K:Mo molar ratio of 1, and the method was the same as that in Example 2.

[0033] At the same time, a control catalyst was prepared by the impregnation method with a K:Mo molar ratio of 1, and the method was the same as that in Example 2.

[0034] 2. The core-shell K1-MoO3@SiO2 catalyst and the control catalyst were applied in the synthesis of methanethiol. The synthesis conditions were the same as those in Example 2. As a result, for the core-shell K1-MoO3@SiO2 catalyst, the conversion rate of CO was 54%, and the selectivity for CH3SH was 56%. For the control catalyst, the conversion rate of CO was 33%, and the selectivity for CH3SH was 38%. The core-shell K1-MoO3@SiO2 catalyst and the control catalyst were applied in the synthesis of ethanethiol. The synthesis conditions were the same as those in Example 2. As a result, for the core-shell K1-MoO3@SiO2 catalyst, the conversion rate of C2H4 was 68%, and the selectivity for C2H5SH was 59%. For the control catalyst, the conversion rate of C2H4 was 49%, and the selectivity for C2H5SH was 53%.

[0035] The core-shell K1-MoO3@SiO2 catalyst and the control catalyst were applied in the synthesis of ethanethiol. The synthesis conditions were the same as those in Example 2. As a result, for the core-shell K1-MoO3@SiO2 catalyst, the conversion rate of C2H4 was 68%, and the selectivity for C2H5SH was 59%. For the control catalyst, the conversion rate of C2H4 was 49%, and the selectivity for C2H5SH was 53%.

[0036] Example 5: Preparation and application of the core-shell K3-MoO3@SiO2 catalyst of the present invention

[0037] 1. The preparation method of the core-shell K3-MoO3@SiO2 catalyst was the same as that in Step 1 of Example 2, except that the molar ratio of K:Mo was 3. At the same time, a control catalyst was prepared by the impregnation method with a K:Mo molar ratio of 1, and the method was the same as that in Example 3.

[0038] At the same time, a control catalyst was prepared by the impregnation method with a K:Mo molar ratio of 1, and the method was the same as that in Example 3.

[0039] 2. The core-shell K3-MoO3@SiO2 catalyst and the control catalyst were applied in the synthesis of methanethiol. The synthesis conditions were the same as those in Example 2. As a result, for the core-shell K3-MoO3@SiO2 catalyst, the conversion rate of CO was 57%, and the selectivity for CH3SH was 61%. For the control catalyst, the conversion rate of CO was 35%, and the selectivity for CH3SH was 45%.

[0040] The core-shell K3-MoO3@SiO2 catalyst and the control catalyst were applied to the synthesis of ethanethiol under the same synthesis conditions as in Example 2. As a result, the conversion rate of C2H4 over the core-shell K3-MoO3@SiO2 catalyst was 72%, and the selectivity for C2H5SH was 70%; the conversion rate of C2H4 over the control catalyst was 58%, and the selectivity for C2H5SH was 66%.

[0041] Example 6: Preparation and application of the core-shell K2-MoO3@0.5SiO2 catalyst of the present invention

[0042] 1. 150 mg of ammonium molybdate was placed in 32 mL of an ethanol solution of polyvinylpyrrolidone (31% ethanol solution containing 400 mg of PVP). After stirring for 1 h, the mixture was transferred to a polytetrafluoroethylene autoclave and reacted at 200 °C for 20 h. After centrifugation, the solid was washed with a mixed solution of ethanol and acetone and dried at 100 °C to obtain MoO2. 30 mg of MoO2 was placed in 53 mL of an ethanol solution with a volume concentration of 37%. After ultrasonic treatment for 1 h, 0.2 mL of diethanolamine and 0.73 g of cetyltrimethylammonium bromide were added to the dispersion under room temperature and stirring. Then, 0.2 mL of tetraethyl orthosilicate was added dropwise, and stirring was continued for 24 h. After centrifugation, the solid was washed with a mixed solution of ethanol and acetone, dried at 100 °C, and then calcined at 550 °C for 6 h to obtain the MoO3@0.5SiO2 catalyst. The core-shell MoO3@0.5SiO2 material was added to a potassium carbonate solution with a K:Mo molar ratio of 2. After stirring well, it was ultrasonicated for 10 min, allowed to stand overnight, dried at 100 °C, and calcined at 550 °C for 6 h to obtain the core-shell K2-MoO3@0.5SiO2 catalyst.

[0043] 2. After the core-shell K2-MoO3@SiO2 catalyst and the control catalyst prepared in step 1 were respectively ground and sieved to 40-60 mesh, 0.4 g of each was taken and loaded into a tubular furnace reactor. A CO / H2 / H2S mixed gas (the molar concentration of CO in the mixed gas was 100000 ppm, the molar concentration of H2 in the mixed gas was 400000 ppm, and the molar concentration of H2S in the mixed gas was 500000 ppm) was introduced and reacted at 0.2 MPa and 400 °C to synthesize CH3SH. The total gas feed space velocity was 3000 h -1 ; the conversion rate of CO over the core-shell K2-MoO3@SiO2 catalyst was 66%, and the selectivity for CH3SH was 83%;

[0044] After the core-shell K2-MoO3@SiO2 catalyst and the control catalyst prepared in Step 1 are ground and sieved to 40-60 mesh respectively, 0.4 g is taken and loaded into a tubular furnace reactor, and a C2H4 / H2S mixed gas (the molar concentration of C2H4 in the mixed gas is 250,000 ppm, and the molar concentration of H2S in the mixed gas is 750,000 ppm) is introduced to synthesize C2H5SH at 1.6 MPa and 240 °C, and the total gas feed space velocity is 3000 h -1 , the conversion rate of C2H4 by the core-shell K2-MoO3@SiO2 catalyst is 87%, and the selectivity of C2H5SH is 97%.

Claims

1. A core-shell K x -MoO3@SiO2 catalyst for use in the synthesis of methanethiol or ethanethiol; The preparation of the core-shell K x -MoO3@SiO2 catalyst is as follows: Molybdate is placed in an ethanol solution of polyvinylpyrrolidone, stirred and mixed evenly, and then reacted at 150-240 °C for 15-24 h. After solid-liquid separation, the solid is washed and dried to obtain MoO2; 10-50 mg of MoO2 is placed in an ethanol solution with a volume concentration of 15-40%. After ultrasonic dispersion, 0.2-1 mL of diethanolamine and 0.5-3 g of cetyltrimethylammonium bromide are added to the dispersion under stirring at room temperature. Then, 0.2-1.6 mL of tetraethyl orthosilicate is added dropwise, and stirring is continued for 10-30 h. After solid-liquid separation, the solid is washed, dried and then calcined to obtain the core-shell MoO3@SiO2 material; The core-shell MoO3@SiO2 material is added to the potassium precursor solution, mixed evenly, ultrasonicated, allowed to stand overnight, dried and calcined to obtain the core-shell Kx-MoO3@SiO2 catalyst, and x = 0.5-3; Prepare methanethiol using a mixed gas of CO, H2, and H2S as raw materials, and prepare ethanethiol using a mixed gas of C2H4 and H2S as raw materials.

2. The application according to claim 1, characterized in that: The mass ratio of molybdate to polyvinylpyrrolidone is 1:2 to 5, and the volume concentration of the ethanol solution in the ethanol solution of polyvinylpyrrolidone is 15 to 40%.

3. The application according to claim 1, wherein: The potassium precursor is one of potassium carbonate, potassium sulfide, and potassium sulfate.

4. The application according to claim 1, wherein: The calcination temperature is treated at 450 to 650 °C for 2 to 8 h.

5. The application according to claim 1, wherein: The molar ratio of K:Mo is 0.5 to 3:1.

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