A method for preparing tert-dodecyl mercaptan using a modified Y molecular sieve catalyst

Abstract

The present invention relates to a method for preparing tert-dodecyl mercaptan using a modified Y molecular sieve catalyst, wherein the modified Y molecular sieve catalyst is used for the reaction of triisobutylene and hydrogen sulfide to prepare tert-dodecyl mercaptan. The method of the present invention has high product selectivity, long catalyst life, low reaction energy consumption, obvious economic advantages, and is particularly suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing tert-dodecyl mercaptan by using a modified Y molecular sieve catalyst. Background Art

[0002] Tert-dodecyl mercaptan is used as a chain transfer agent to regulate molecular weight during the polymerization process. It is a typical polymer molecular weight regulator. Its downstream applications include the production of ABS, styrene-butadiene rubber, nitrile rubber, polystyrene and other products.

[0003] Uncle dodecyl mercaptan can be prepared by reacting triisobutylene with hydrogen sulfide. US4582939 uses A-15 resin as a catalyst to catalyze the addition reaction of triisobutylene with hydrogen sulfide in a stainless steel tube. At 73-108°C, the catalyst is deactivated after 12 hours of reaction. The mercaptan yield is 92%, the olefin conversion rate is 88%, and a large amount of tert-butyl mercaptan and tert-octyl mercaptan are generated. The catalyst has obvious carbon deposition. US4891445 uses A-15 resin as a catalyst and the reaction temperature is below 20°C to prepare tert-dodecyl mercaptan. The temperature is reduced and the product selectivity is increased. However, the low temperature reaction has high refrigeration energy consumption. If it is used for industrial production, the cost will increase significantly. KR20060113045A uses Y molecular sieve as a catalyst and uses a reaction temperature below 20°C to avoid the cracking of TIB to generate tert-butyl mercaptan and tert-octyl mercaptan, thereby improving the selectivity of the product.

[0004] When Y molecular sieve is used as a catalyst to synthesize tert-dodecyl mercaptan, the catalyst is easily deactivated. The main reason is carbon deposition. In addition, the catalyst is highly acidic. The product selectivity can only be improved when the reaction is carried out at a low temperature. As the temperature rises, the selectivity of the TIB cracking byproducts tert-butyl mercaptan and tert-octyl mercaptan increases sharply. The synthesis of tert-dodecyl mercaptan using triisobutylene as a raw material was only reported in patents by some foreign scholars in the last century. In recent years, few domestic and foreign scholars have conducted further research. Therefore, there is an urgent need for an economical and stable method for producing tert-dodecyl mercaptan. Summary of the invention

[0005] The invention provides a method for preparing tert-dodecyl mercaptan by catalyzing the addition of triisobutylene and hydrogen sulfide. The catalyst activity is improved and the catalyst life is increased.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing tert-dodecyl mercaptan using a modified Y molecular sieve catalyst comprises taking triisobutylene and hydrogen sulfide as raw materials and using the modified Y molecular sieve as a catalyst to prepare tert-dodecyl mercaptan through a catalytic reaction, wherein the modified Y molecular sieve is a multi-level pore Y molecular sieve treated with an organic acid and a pyridine solution.

[0008] In a specific embodiment, the Y molecular sieve is selected from any one of HY molecular sieve, USY molecular sieve, mesoporous Y molecular sieve or rare earth Y molecular sieve.

[0009] In a specific embodiment, the organic acid for modifying the Y molecular sieve is selected from at least one of tartaric acid, oxalic acid, citric acid, benzoic acid, and salicylic acid, preferably oxalic acid or citric acid.

[0010] In a specific embodiment, the method of organic acid treatment is: mixing Y molecular sieve and organic acid in a mass ratio of 1000:1 to 100:1, stirring and drying the catalyst.

[0011] In a preferred embodiment, Y molecular sieve and organic acid are mixed in a mass ratio of 500:1-200:1, the treatment temperature is 60-80°C, the stirring speed is 300-600r / min, the treatment time is 5-10h, and the catalyst is dried after the treatment, the drying temperature is 60-200°C, and the drying time is 12-48h.

[0012] In a specific embodiment, the modified Y molecular sieve obtained after the organic acid treatment is placed in a fixed bed, and a pyridine solution is introduced, the mass ratio of the pyridine solution to the modified Y molecular sieve is 100:1-10:1, preferably 60:1-40:1, the treatment temperature is 240-260°C, the treatment time is 28-30h, and after the treatment is completed, the catalyst is dried at a drying temperature of 80-150°C and a drying time of 6-12h.

[0013] In a specific embodiment, the catalytic reaction is carried out in a fixed bed.

[0014] In a specific embodiment, a mixture of triisobutylene and hydrogen sulfide is introduced into a fixed bed reactor filled with a modified Y molecular sieve catalyst for catalytic reaction. Both upper and lower feeding are possible. Preferably, the feeding method is upper feeding. The space velocity of triisobutylene is 0.5-2h -1 , the molar ratio of hydrogen sulfide to triisobutylene is 2:1-8:1.

[0015] In a preferred embodiment, the space velocity of triisobutylene is 1-1.5h -1 , the molar ratio of hydrogen sulfide to triisobutylene is 3:1-5:1.

[0016] In a specific embodiment, the reaction temperature is 20-120°C, preferably 40-80°C, and the reaction pressure is 1-5Mpa, preferably 1.2-3Mpa.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The method of the present invention uses a multi-level pore Y molecular sieve treated with an organic acid and a pyridine solution as a catalyst to catalyze the reaction of triisobutylene and hydrogen sulfide to prepare tert-dodecyl mercaptan, thereby greatly improving product selectivity and catalyst life. Meanwhile, compared with the reaction temperature of the untreated Y molecular sieve catalyzing the present reaction being only 10-20° C., the applicable catalytic reaction temperature of the catalyst is improved, thereby greatly reducing refrigeration energy consumption. Meanwhile, the reaction of the present invention is an exothermic reaction, and no additional heating energy consumption is required. DETAILED DESCRIPTION

[0019] In order to better understand the technical solution of the present invention, the following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the claims of the present invention.

[0020] A method for preparing tert-dodecyl mercaptan using a modified Y molecular sieve catalyst, using triisobutylene and hydrogen sulfide as raw materials, using a modified Y molecular sieve as a catalyst, and catalytic reaction to prepare tert-dodecyl mercaptan, wherein the modified Y molecular sieve is a multi-level pore Y molecular sieve treated with an organic acid and a pyridine solution. The Y-type molecular sieve is not particularly limited, and can be any common Y molecular sieve, for example, any one of HY molecular sieve, USY molecular sieve, mesoporous Y molecular sieve or rare earth Y molecular sieve.

[0021] The specific preparation method of the modified Y molecular sieve is, for example: the Y molecular sieve is first treated with an organic acid, and then treated with a pyridine solution to obtain the modified multi-level pore Y molecular sieve.

[0022] The organic acid treatment step is, for example, placing Y molecular sieve and organic acid in a beaker at a mass ratio of 1000:1 to 100:1, preferably 500:1-200:1, at a treatment temperature of 60-80°C, a stirring speed of 300r / min, a treatment time of 10h, and after the treatment, drying the catalyst at a drying temperature of 60-200°C and a drying time of 12-48h.

[0023] Wherein, the organic acid is selected from at least one of tartaric acid, oxalic acid, citric acid, benzoic acid, and salicylic acid, preferably oxalic acid and citric acid. The mass ratio of Y molecular sieve and organic acid is 1000:1-100:1, for example, including but not limited to 100:1, 200:1, 300:1, 400:1, 500:1, 600:1, 700:1, 800:1, 900:1, 1000:1, preferably 500:1-200:1. In this step, the treatment temperature is 60-80°C, for example, including but not limited to 60°C, 65°C, 70°C, 75°C, and 80°C. The organic acid is stirred while being treated, the stirring speed is 300r / min, and the treatment time is 10h. After the treatment is completed, the catalyst is dried at a drying temperature of 60-200°C, including but not limited to 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, and a drying time of 12-48h, including but not limited to 12h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 48h.

[0024] After the organic acid treatment, the modified Y molecular sieve obtained after the organic acid treatment is placed in a fixed bed, and a pyridine solution is introduced, wherein the mass ratio of the pyridine solution to the modified Y molecular sieve is 100:1-10:1, for example, including but not limited to 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, preferably 60:1-40:1, and the treatment temperature is 240-260°C, for example, including but not limited to 240 ℃, 245℃, 250℃, 255℃, 260℃, treatment time 28-30h, for example, 28h, 29h, 30h, etc., after the treatment, the catalyst is dried, the drying temperature is 80-150℃, for example, including but not limited to 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, drying time 6-12h, for example, including but not limited to 6h, 7h, 8h, 9h, 10h, 11h, 12h.

[0025] The molecular sieve treated with organic acid has a multi-level pore structure, which can effectively reduce the diffusion resistance of triisobutylene inside the molecular sieve, increase mass transfer, reduce carbon deposition, and significantly improve the life of the catalyst. The modified molecular sieve removes part of the framework aluminum, reduces L acid, reduces acidity, reduces the selectivity of TIB cracking byproducts tert-butyl mercaptan and tert-octyl mercaptan, and increases the selectivity of tert-dodecyl mercaptan. Pyridine can occupy part of the micropores of the molecular sieve, reduce the carbon deposition of the molecular sieve during the reaction and the TIB cracking side reaction occurring in the micropores, increase the product selectivity and the life of the catalyst. Through the synergistic effect of organic acid post-treatment and pyridine adsorption, the reaction temperature can be greatly increased, and the product selectivity and catalyst life are also significantly improved.

[0026] The catalytic reaction of the present invention adopts a fixed bed. Specifically, a mixture of triisobutylene and hydrogen sulfide is introduced into a fixed bed reactor loaded with a catalyst, and the feeding method is top feeding, and the space velocity of triisobutylene is 0.5-2h -1 , for example including but not limited to 0.5h -1 , 1h -1 , 1.5h -1 , 2h -1 , preferably 1-1.5h -1 The molar ratio of hydrogen sulfide to triisobutylene is 2:1-8:1, for example including but not limited to 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, preferably 3:1-5:1.

[0027] The reaction temperature of the catalytic reaction of the present invention is 20-120°C, for example including but not limited to 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, preferably 40-80°C, and the reaction pressure is 1-5Mpa (gauge pressure), for example including but not limited to 1Mpa, 2Mpa, 3Mpa, 4Mpa, 5Mpa, preferably 1.2-3Mpa.

[0028] The present invention will be further described in detail below in conjunction with more specific embodiments, but shall not be construed as limiting in any way.

[0029] The main raw materials used in the following examples are from the following sources:

[0030] HY molecular sieve, USY molecular sieve, mesoporous Y molecular sieve, and rare earth Y molecular sieve come from the catalyst factory of Nankai University. Hydrogen sulfide comes from Dalian Datai Gas with a purity of 99.9%. Tartaric acid, oxalic acid, citric acid, benzoic acid, and salicylic acid come from Sinopharm Reagent with a reagent-grade purity. Pyridine solution comes from Sinopharm Reagent with a chromatographic grade purity.

[0031] The analytical instruments and methods used in the embodiments are as follows:

[0032] Gas chromatograph: Agilent-7820;

[0033] Gas chromatography column: 0.25mm×30m DB-5 capillary column, detector FID, vaporization chamber temperature 280℃, column box temperature 280℃, FID detector temperature 300℃, argon flow rate 2.1mL / min, hydrogen flow rate 30mL / min, air flow rate 400mL / min, injection volume 1.0μL. The conversion rate of olefins and the selectivity of products were calculated using the area normalization method. Heating program: preheat to column temperature 40℃, maintain for 5min, increase from 40℃ to 280℃ at a rate of 15℃ / min, and maintain for 2min.

[0034] All conversion and selectivity statistics below are from chromatographic analysis.

[0035] Example 1

[0036] (1) Catalyst preparation: Weigh 300g of HY molecular sieve and 1g of oxalic acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 10h. After the treatment, dry the catalyst at 150°C for 30h. Place the prepared organic acid-modified Y molecular sieve in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 100:1. Treat at 250°C for 30h. After the treatment, dry the catalyst at 120°C for 9h.

[0037] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 0.5 h -1 The molar ratio of hydrogen sulfide to olefin is 2:1, the reaction temperature is 20°C, the pressure is 1MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >89%, and the continuous operation is 3000h, the conversion rate is 78%, and the selectivity is >89%.

[0038] Example 2

[0039] (1) Catalyst preparation: Weigh 300g of USY molecular sieve and 1g of oxalic acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 10h. After the treatment, dry the catalyst at 150°C for 30h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 60:1. Treat at 240°C for 28h. After the treatment, dry the catalyst at 100°C for 10h.

[0040] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 1 h -1 The molar ratio of hydrogen sulfide to olefin is 4:1, the reaction temperature is 60°C, the pressure is 2MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >99%, the continuous operation is 3000h, the conversion rate is 84%, and the selectivity is >99%.

[0041] Example 3

[0042] (1) Catalyst preparation: Weigh 300g of mesoporous Y molecular sieve and 1g of oxalic acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 10h. After the treatment, dry the catalyst at 150°C for 30h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 40:1. Treat at 240°C for 29h. After the treatment, dry the catalyst at 80°C for 12h.

[0043] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 1.5 h -1 The molar ratio of hydrogen sulfide to olefin is 6:1, the reaction temperature is 80°C, the pressure is 5MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >99%, the continuous operation is 3000h, the conversion rate is 83%, and the selectivity is >99%.

[0044] Example 4

[0045] (1) Catalyst preparation: Weigh 300g of rare earth Y molecular sieve and 1g of oxalic acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 10h. After the treatment, dry the catalyst at 150°C for 30h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 10:1. Treat at 250°C for 30h. After the treatment, dry the catalyst at 150°C for 6h.

[0046] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 2 h -1 The molar ratio of hydrogen sulfide to olefin is 8:1, the reaction temperature is 120°C, the pressure is 5MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >90%, the continuous operation is 3000h, the conversion rate is 79%, and the selectivity is >90%.

[0047] Example 5

[0048] (1) Catalyst preparation: Weigh 1000g of HY molecular sieve and 1g of oxalic acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 10h. After the treatment, dry the catalyst at 150°C and 12h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 40:1. Treat at 250°C and 30h. After the treatment, dry the catalyst at 120°C and 9h.

[0049] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 0.5 h -1 The molar ratio of hydrogen sulfide to olefin is 2:1, the reaction temperature is 20°C, the pressure is 1MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >94%, and the continuous operation is 3000h, the conversion rate is 78%, and the selectivity is >94%.

[0050] Example 6

[0051] (1) Catalyst preparation: Weigh 500g of USY molecular sieve and 1g of oxalic acid to make a solution and place it in a beaker. Treat it at 80°C and stirring speed of 400r / min for 8h. After treatment, dry the catalyst at 180°C and 15h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 40:1. Treat at 250°C and 30h. After treatment, dry the catalyst at 120°C and 9h.

[0052] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 1 h -1 The molar ratio of hydrogen sulfide to olefin is 4:1, the reaction temperature is 60°C, the pressure is 2MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >99%, the continuous operation is 3000h, the conversion rate is 84%, and the selectivity is >99%.

[0053] Example 7

[0054] (1) Catalyst preparation: Weigh 200g of mesoporous Y molecular sieve and 1g of oxalic acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 5h. After the treatment, dry the catalyst at 200°C and 45h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 40:1. Treat at 250°C and 30h. After the treatment, dry the catalyst at 120°C and 9h.

[0055] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 1.5 h -1 The molar ratio of hydrogen sulfide to olefin is 6:1, the reaction temperature is 80°C, the pressure is 1MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >99%, the continuous operation is 3000h, the conversion rate is 83%, and the selectivity is >99%.

[0056] Example 8

[0057] (1) Catalyst preparation: Weigh 100g of rare earth Y molecular sieve and 1g of oxalic acid to make a solution and place it in a beaker. Treat it at 60°C and stirring speed 600r / min for 10h. After the treatment, dry the catalyst at 60°C and 48h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 40:1. Treat at 250°C and 30h. After the treatment, dry the catalyst at 120°C and 9h.

[0058] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 2 h -1 The molar ratio of hydrogen sulfide to olefin is 8:1, the reaction temperature is 120°C, the pressure is 2MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >94%, and the continuous operation is 3000h, the conversion rate is 80%, and the selectivity is >94%.

[0059] Example 9

[0060] (1) Catalyst preparation: Weigh 300g of HY molecular sieve and 1g of citric acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 10h. After the treatment, dry the catalyst at 150°C for 30h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 40:1. Treat at 250°C for 30h. After the treatment, dry the catalyst at 120°C for 9h.

[0061] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 0.5 h -1 The molar ratio of hydrogen sulfide to olefin is 2:1, the reaction temperature is 20°C, the pressure is 5MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >99%, the continuous operation is 3000h, the conversion rate is 83%, and the selectivity is >99%.

[0062] Example 10

[0063] (1) Catalyst preparation: Weigh 300g of USY molecular sieve and 1g of tartaric acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 10h. After the treatment, dry the catalyst at 150°C for 30h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 40:1. Treat at 250°C for 30h. After the treatment, dry the catalyst at 120°C for 9h.

[0064] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 1 h -1 The molar ratio of hydrogen sulfide to olefin is 4:1, the reaction temperature is 60°C, the pressure is 1MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >99%, the continuous operation is 3000h, the conversion rate is 81%, and the selectivity is >99%.

[0065] Embodiment 11

[0066] (1) Catalyst preparation: Weigh 300g of mesoporous Y molecular sieve and 1g of benzoic acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 10h. After the treatment, dry the catalyst at 150°C for 30h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 40:1. Treat at 250°C for 30h. After the treatment, dry the catalyst at 120°C for 9h.

[0067] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 1.5 h -1 The molar ratio of hydrogen sulfide to olefin is 6:1, the reaction temperature is 80°C, the pressure is 2MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >99%, the continuous operation is 3000h, the conversion rate is 82%, and the selectivity is >99%.

[0068] Example 12

[0069] (1) Catalyst preparation: Weigh 300g of rare earth Y molecular sieve and 1g of salicylic acid to make a solution and place it in a beaker. Treat it at 70°C and stirring speed of 300r / min for 10h. After the treatment, dry the catalyst at 150°C for 30h. Place the Y molecular sieve modified with organic acid in a fixed bed and pass pyridine solution. The mass ratio of pyridine solution to modified Y molecular sieve is 40:1. Treat at 250°C for 30h. After the treatment, dry the catalyst at 120°C for 9h.

[0070] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 2 h -1 The molar ratio of hydrogen sulfide to olefin is 8:1, the reaction temperature is 120°C, the pressure is 5MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >99%, the continuous operation is 3000h, the conversion rate is 82%, and the selectivity is >99%.

[0071] Comparative Example 1

[0072] Using the Y molecular sieve catalyst in KR20060113045A, the reaction conditions in Example 1 were repeated, with a TIB conversion rate of 88% and a TDM selectivity of 45%. After continuous operation for 3000 h, the TIB conversion rate decreased to 7% and the TDM selectivity to 45%.

[0073] Comparative Example 2

[0074] (1) Catalyst preparation: Weigh 200 g of mesoporous Y molecular sieve and 1 g of oxalic acid to make a solution and place it in a beaker. Treat it at 70° C. and stirring speed 300 r / min for 5 h. After the treatment, dry the catalyst at 200° C. and drying time 45 h.

[0075] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 1.5 h -1 The molar ratio of hydrogen sulfide to olefin is 6:1, the reaction temperature is 80°C, the pressure is 1MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >76%, the continuous operation is 3000h, the conversion rate is 70%, and the selectivity is >66%.

[0076] Comparative Example 3

[0077] (1) Catalyst preparation: The mesoporous Y molecular sieve was placed in a fixed bed and a pyridine solution was introduced. The mass ratio of the pyridine solution to the modified Y molecular sieve was 40:1. The treatment temperature was 240°C and the treatment time was 29 hours. After the treatment, the catalyst was dried at 80°C for 12 hours.

[0078] (2) Take 100 ml of the modified molecular sieve catalyst prepared above and load it into a fixed bed. The feed space velocity of triisobutylene is 1.5 h -1 The molar ratio of hydrogen sulfide to olefin is 6:1, the reaction temperature is 80°C, the pressure is 5MpaKpG, the TIB conversion rate is 88%, the TDM selectivity is >73%, the continuous operation is 3000h, the conversion rate is 68%, and the selectivity is >63%.

[0079] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as limiting the present invention. Those skilled in the art will appreciate that, under the guidance of this specification, some modifications or adjustments may be made to the present invention. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for preparing tert-dodecyl mercaptan using a modified Y molecular sieve catalyst, characterized in that: Using triisobutylene and hydrogen sulfide as raw materials and modified Y molecular sieve as catalyst, tert-dodecyl mercaptan is prepared by catalytic reaction, wherein the modified Y molecular sieve is a multi-level pore Y molecular sieve treated with an organic acid and a pyridine solution; The Y molecular sieve is selected from any one of HY molecular sieve, USY molecular sieve, mesoporous Y molecular sieve or rare earth Y molecular sieve; The organic acid for modifying the Y molecular sieve is selected from at least one of tartaric acid, oxalic acid, citric acid, benzoic acid and salicylic acid; The method of organic acid treatment is: mix Y molecular sieve and organic acid in a mass ratio of 1000:1 to 100:1, stir and dry the catalyst: The method of pyridine solution treatment is: placing the modified Y molecular sieve obtained after organic acid treatment in a fixed bed, passing pyridine solution, the mass ratio of pyridine solution to modified Y molecular sieve is 100:1-10:1, the treatment temperature is 240-260°C, the treatment time is 28-30h, and the catalyst is dried after the treatment is completed.

2. The method according to claim 1, characterized in that The organic acids used to modify the Y molecular sieve are oxalic acid and citric acid.

3. The method according to claim 1, characterized in that Mix Y molecular sieve and organic acid in a mass ratio of 500:1-200:1, the treatment temperature is 60-80°C, the stirring speed is 300-600r / min, and the treatment time is 5-10h. After the treatment, dry the catalyst at a drying temperature of 60-200°C and a drying time of 12-48h.

4. The method according to claim 1, characterized in that: The modified Y molecular sieve obtained after the organic acid treatment is placed in a fixed bed, and a pyridine solution is introduced, wherein the mass ratio of the pyridine solution to the modified Y molecular sieve is 60:1-40:1, the drying temperature of the catalyst is 80-150°C, and the drying time is 6-12h.

5. The method according to claim 1, characterized in that The catalytic reaction is carried out in a fixed bed.

6. The method according to any one of claims 1 to 5, characterized in that: A mixture of triisobutylene and hydrogen sulfide is introduced into a fixed bed reactor filled with a modified Y molecular sieve catalyst for catalytic reaction.

7. The method according to claim 6, characterized in that The feeding method is top feeding, and the space velocity of triisobutylene is 0.5-2h -1 , the molar ratio of hydrogen sulfide to triisobutylene is 2:1-8:

1.

8. The method according to claim 7, characterized in that The space velocity of triisobutylene is 1-1.5h -1 , the molar ratio of hydrogen sulfide to triisobutylene is 3:1-5:

1.

9. The preparation method according to claim 6, characterized in that: The reaction temperature is 20-120°C, and the reaction pressure is 1-5Mpa.

10. The preparation method according to claim 9, characterized in that: The reaction temperature is 40-80°C and the reaction pressure is 1.2-3Mpa.