The invention relates to a method for synthesizing 2, 2apos; platinum-carbon catalyst for 2-dichlorohydrazobenzene and preparation method of platinum-carbon catalyst

Abstract

The invention relates to the technical field of catalysts, and particularly discloses a platinum-carbon catalyst for synthesizing 2, 2 '-dichlorohydrazobenzene and a preparation method thereof.According to the platinum-carbon catalyst for synthesizing 2, 2'-dichlorohydrazobenzene, the modified Pt-Fe / C catalyst is matched with feeding of naphthoquinone, an emulsifier and alkali, in the hydrogenation synthesis reaction of 2, 2 '-dichlorohydrazobenzene, the yield of 2, 2'-dichlorohydrazobenzene is remarkably increased, and the yield of 2, 2 '-dichlorohydrazobenzene is increased. By adopting the method, the unit cost of the catalyst in the production of 2, 2 '-dichlorohydroazobenzene can be remarkably reduced, the catalytic effect of the Pt-Fe / C catalyst after secondary activation after use is good, the service life of the catalyst can be remarkably prolonged, the effect of the catalyst after activation can be remarkably improved, the effective circulation frequency is increased, the activation frequency is reduced in production, and the production cost is reduced. The Pt-Fe / C catalyst activation mode can adopt simple acid leaching hydrogen reduction, the requirement of activation equipment is lower than that of ultraviolet irradiation and other methods, and the operation cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and specifically discloses a platinum-carbon catalyst for synthesizing 2,2'-dichlorohydrazobenzene and a preparation method thereof. Background Art

[0002] 3,3'-Dichlorobenzidine hydrochloride (DCB) is an important organic intermediate and has wide applications in the fields of optoelectronic materials, dyes, and polymer materials. Currently, the industrial production of DCB mainly adopts a three-step process: o-chloronitrobenzene is catalytically hydrogenated under alkaline conditions with a naphthoquinone derivative as a co-catalyst, in combination with an emulsifier and toluene solvent, at a hydrogen pressure of 0.5 MPa and an appropriate temperature to obtain 2,2'-dichlorohydrazobenzene. Subsequently, it is rearranged in a sulfuric acid medium to 3,3'-dichlorobenzidine sulfate, and finally the target product DCB is obtained by salting with hydrochloric acid.

[0003] 2,2'-Dichlorohydrazobenzene is an important intermediate for DCB synthesis. The synthesis of 2,2'-dichlorohydrazobenzene is widely carried out by the reaction of o-chloronitrobenzene under the action of a platinum-carbon catalyst. However, there is still room for improvement in the catalytic synthesis of 2,2'-dichlorohydrazobenzene. For example, in terms of reaction efficiency, although the mesoporous carbon-supported platinum catalyst (Pt 0.5-5 wt%) disclosed in Patent CN102671656A can achieve a yield of more than 95% of 2,2'-dichlorohydrazobenzene, it requires a reaction time of 3-10 hours, and the activity of the catalyst may decay after being reused 8 times; although the multi-stage hydrogenation process adopted in Patent CN118477592A can control the by-product o-chloroaniline at 0.36%, it requires a complex catalyst preparation process (palladium nitrate / copper / zinc composite loading) and high-temperature calcination conditions at 480-500 °C.

[0004] Due to the precious metal nature of platinum, the platinum-carbon catalyst accounts for a non-negligible part of the production cost. The manufacturing methods of the platinum-carbon catalyst include co-precipitation method, chemical reduction method, deposition-deposition method, etc. At the same loading amount, different processes result in significant differences in production cost and performance. The noble metal loading amount of the platinum-carbon catalyst, the catalytic performance of the catalyst, the number of stable catalyst cycles, and the regeneration performance of the catalyst directly affect the production cost of DCB. Multiple existing patents have conducted research in this regard. For example, in order to avoid the destruction of the catalyst during the activation process, CN113333034A generates nano-titanium dioxide photoactive sites in-situ and activates the catalyst by means of ultraviolet light irradiation, achieving good results. However, the treatment cost of the catalyst has not reached the optimal level. In terms of by-products, in the paper "Preparation of 3,3'-Dichlorobenzidine by Pd / C Catalytic Hydrogenation" by Yan Maowen of Dalian University of Technology (2005), using a Pd / C catalyst and reacting for 12-15 hours, the content of by-product o-chloroaniline still reaches 5%-10%, and the catalyst needs to be frequently replenished. After at least 14 cycles of hydrogenation, the chromatographic purity of the organic phase is higher than 90% and the activity does not decrease significantly.

[0005] Although these solutions can achieve relatively good effects from some perspectives, there are still obvious limitations. High-loading noble metals lead to excessively high catalyst costs, multi-stage reactions complicate the process, continuous devices bring huge equipment investments, the cost of catalyst activation methods is too high, and the number of stable catalyst cycles is not good. Summary of the Invention

[0006] In view of the problems existing in the prior art, a first aspect of the present invention proposes a method for preparing a Pt-Fe / C catalyst, including: Step 1: Disperse the carrier carbon in water, then add a soluble iron salt, separate, and dry to obtain an iron-loaded carbon carrier; Step 2: Disperse the iron-loaded carbon carrier in water again, add a platinum salt solution, mix evenly, separate, and dry to obtain a dried product; Step 3: Heat and sinter the dried product in a hydrogen atmosphere to obtain a Pt-Fe / C catalyst.

[0007] In some specific embodiments of the first aspect, in Step 1, 150-250 g of carrier carbon is dispersed in each 1 L of water. In some embodiments, in Step 1, 160 g, 170 g, 180 g, 190 g, 200 g, 210 g, 220 g, 230 g, 240 g, or 250 g of carrier carbon is optionally dispersed in each 1 L of water.

[0008] In some specific embodiments of the first aspect, in Step 1, the iron salt is a soluble iron salt.

[0009] In some specific embodiments of the first aspect, the soluble iron salt is one of ferric chloride, ferrous chloride, ferric nitrate, and ferric sulfate.

[0010] In some specific embodiments of the first aspect, in step 1, based on iron, the mass ratio of the iron salt to the carrier carbon in the feed is (4 - 6):1. In some specific embodiments of the first aspect, in step 1, based on iron, the mass ratio of the iron salt to the carrier carbon in the feed is optionally 4:1, 5:1, or 6:1.

[0011] In some specific embodiments of the first aspect, the carrier carbon is one or more of activated carbon, carbon fiber, mesoporous carbon, and carbon nanotubes.

[0012] In some specific embodiments of the first aspect, in step 1, the drying temperature is 80 - 120°C. In some specific embodiments of the first aspect, in step 1, the drying temperature is optionally 90°C, 100°C, 110°C, or 120°C.

[0013] In some specific embodiments of the first aspect, in step 2, 150 - 250 g of the carbon carrier loaded with dispersed iron is added per 1 L of water. In some specific embodiments of the first aspect, in step 2, 170 g, 180 g, 190 g, 200 g, 210 g, 220 g, 230 g, or 240 g of the carbon carrier loaded with dispersed iron is added per 1 L of water.

[0014] In some specific embodiments of the first aspect, in step 2, 10 - 15 mmol of platinum salt is added per 1 L of water. In some specific embodiments of the first aspect, in step 2, 11 mmol, 12 mmol, 13 mmol, or 14 mmol of platinum salt is optionally added per 1 L of water.

[0015] In some specific embodiments of the first aspect, in step 2, the platinum salt is any one or a mixture of platinum chloride, chloroplatinic acid, and platinum nitrate.

[0016] In some specific embodiments of the first aspect, in step 2, the platinum salt solution is an aqueous solution of the platinum salt.

[0017] In some specific embodiments of the first aspect, the platinum salt solution is added by dropwise addition.

[0018] In some specific embodiments of the first aspect, after mixing in step 2, solid-liquid separation is performed followed by drying.

[0019] In some specific embodiments of the first aspect, the drying temperature is 100 - 120°C. In some specific embodiments of the first aspect, the drying temperature is 110°C.

[0020] In some specific embodiments of the first aspect, the drying time is 7 - 9 h. In some specific embodiments of the first aspect, the drying time is optionally 7 h, 8 h, or 9 h.

[0021] In some specific embodiments of the first aspect, in step 3, the temperature for heat sintering is 200 - 300 °C. In some specific embodiments of the first aspect, in step 3, the temperature for heat sintering is optionally 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, or 290 °C.

[0022] In some specific embodiments of the first aspect, in step 3, the sintering time is 1.5 - 2.5 h. In some specific embodiments of the first aspect, in step 3, the sintering time is optionally 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2.0 h, 2.1 h, 2.2 h, 2.3 h, or 2.4 h.

[0023] The second aspect of the present invention provides a Pt - Fe / C catalyst obtained by the preparation method according to any one of the embodiments of the preparation methods in the first aspect.

[0024] The third aspect of the present invention provides a method for synthesizing 2,2'-dichlorohydrazobenzene, comprising: Mixing the Pt - Fe / C catalyst of the present invention with o - chloronitrobenzene, an organic solvent, and an alkali solution, adding a first auxiliary agent and a second auxiliary agent, heating to a first predetermined temperature, replacing the gas atmosphere with hydrogen, stabilizing the temperature at a second predetermined temperature, pressurizing, and reacting to obtain 2,2'-dichlorohydrazobenzene;

[0025] In some specific embodiments of the third aspect, the feeding mass ratio of the catalyst to o - chloronitrobenzene is 0.1 - 5.0 wt%. In some specific embodiments of the third aspect, the feeding mass ratio of the catalyst to o - chloronitrobenzene is optionally 0.2 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, or 5.0 wt%.

[0026] In some specific embodiments of the third aspect, the organic solvent is selected from one or more of toluene, acetonitrile, methanol, ethanol, isopropanol, and chloroform.

[0027] In some specific embodiments of the third aspect, the first auxiliary agent is selected from one or more of 1,4 - naphthoquinone and 1,2 - naphthoquinone.

[0028] In some specific embodiments of the third aspect, the second auxiliary agent is selected from emulsifiers, and the emulsifier is selected from any one or a combination of nonylphenol polyoxyethylene ether, sodium dodecylbenzenesulfonate, sodium lauroyl sarcosinate, and polyoxyethylene fatty alcohol ether.

[0029] In some specific embodiments of the third aspect, the base is selected from one or more of sodium hydroxide, potassium hydroxide, and triethylamine.

[0030] In some specific embodiments of the third aspect, the base solution is an aqueous solution of the base.

[0031] In some specific embodiments of the third aspect, the mass concentration fraction of the base solution is 16% - 20%. In some specific embodiments of the third aspect, the mass concentration fraction of the base solution is optionally 17%, 18%, 19%, or 20%.

[0032] In some specific embodiments of the third aspect, for every 1 L of the organic solvent, the feeding mass of the first auxiliary agent is 5 - 8 g. In some embodiments, for every 1 L of the organic solvent, the feeding mass of the first auxiliary agent is optionally 5 g, 6 g, 7 g, or 8 g.

[0033] In some specific embodiments of the third aspect, for every 1 L of the organic solvent, the feeding mass of the second auxiliary agent is 2 - 4 g. In some embodiments, for every 1 L of the organic solvent, the feeding mass of the second auxiliary agent is 2 g, 3 g, or 4 g.

[0034] In some specific embodiments of the third aspect, the first predetermined temperature is 65 - 75 °C. In some specific embodiments of the third aspect, the first predetermined temperature is optionally 66 °C, 67 °C, 68 °C, 69 °C, 70 °C, 71 °C, 72 °C, 73 °C, 74 °C, or 75 °C.

[0035] In some specific embodiments of the third aspect, the second predetermined temperature is 75 - 85 °C. In some specific embodiments of the third aspect, the second predetermined temperature is optionally 75 °C, 76 °C, 77 °C, 78 °C, 79 °C, 80 °C, 81 °C, 82 °C, 83 °C, 84 °C, or 85 °C.

[0036] In some specific embodiments of the third aspect, the pressure of hydrogen pressurization is 0.8 - 1.2 Mpa. In some specific embodiments of the third aspect, the pressure of hydrogen pressurization is optionally 0.9 Mpa, 1.0 Mpa, 1.1 Mpa, or 1.2 Mpa.

[0037] The present invention uses liquid chromatography to determine the yield, and the column information is ShimNex CS C18, 5 μm, 4.6×150 mm.

[0038] The present invention has the following beneficial effects: Compared with the existing synthesis methods, the present invention uses the modified Pt-Fe / C catalyst in combination with 1,4-naphthoquinone, sodium dodecylbenzenesulfonate and alkali. In the reaction of hydrogenation synthesis of 2,2'-dichlorohydrazo-benzene, the yield of 2,2'-dichlorohydrazo-benzene is significantly increased, and the output of by-products is reduced. Using this method can significantly reduce the unit cost of the catalyst in the production of 2,2'-dichlorohydrazo-benzene. Compared with other catalysts, the modified Pt-Fe / C catalyst still has good catalytic effect after secondary activation, can significantly increase the service life of the catalyst and the effect after activation, has a high turnover number, reduces the activation times in production, and further reduces the operation cost. Description of the Drawings

[0039] Figure 1 H2-TPR data spectrum of the catalyst prepared in Example 1; Figure 2 TEM spectrum of the catalyst prepared in Example 1; Figure 3 HPLC chromatogram of the product prepared in Example 2. Detailed Description of the Invention

[0040] In order to enable those skilled in the art to better understand the technical solution of the present invention, some non-limiting embodiments are further disclosed below to further illustrate the present invention in detail.

[0041] Example 1 Carrier pretreatment: Weigh 50 g of activated carbon, disperse the activated carbon in 250 ml of ultrapure water, add ferric chloride (10 g in terms of iron element), maintain stirring and dispersion for 24 h, and after solid-liquid separation, dry at 100 °C to obtain an activated carbon carrier loaded with iron; Loading of active components: Weigh 10 g of the carrier obtained in step (1) and disperse it again in 150 ml of ultrapure water. Measure 18.8 ml of 0.1 mol / L chloroplatinic acid solution and drop it into the carrier solution. After dropping, keep stirring and dispersing for 4 h, perform solid-liquid separation, and dry the filter cake at 110 °C for 8 h; Sintering treatment: Sinter the dried product in a hydrogen atmosphere, the sintering temperature is 250 °C, and the sintering time is 2 h. Finally, wash to obtain the Pt-Fe / C catalyst Cat-1.

[0042] Example 2

[0043] 0.15 g of the catalyst Cat-1 prepared in Example 1 was put into a reaction system of 75 g of o-chloronitrobenzene, 65 ml of toluene and 61 ml of 16% sodium hydroxide solution. 0.45 g of 1,4-naphthoquinone and 0.235 g of sodium dodecylbenzenesulfonate were added. The hydrogen was replaced 3 times in a high-pressure resistant reactor, then the temperature was raised to 70 °C, 1.0 MPa of hydrogen was introduced, the temperature was stabilized at 80 °C, and the reaction was carried out for 2 h 50 min under hydrogen pressure. After separation and purification, 2,2'-dichlorohydrazo-benzene was obtained. Sampling and detection showed that the yield of 2,2'-dichlorohydrazo-benzene was 96.8%, and the yield of o-chloroaniline was 2.9%.

[0044] Example 3 The synthesis method of 2,2'-dichlorohydrazo-benzene in Example 2 was used to reuse the catalyst Cat-1 multiple times until the yield of 2,2'-dichlorohydrazo-benzene reached below 55%. The deactivated catalyst obtained in that reuse was numbered Cat-1D.

[0045] Example 4 Example 4 is a method for wet activation of the deactivated catalyst: The deactivated catalyst was added to 1 M hydrochloric acid solution, and the catalyst and the hydrochloric acid solution were mixed at a mass-volume ratio of 1:100 (g / mL). Stir at room temperature for 1 h, then filter by suction. The catalyst was filtered and washed with ultrapure water until the pH of the washing solution was close to neutral. The washed catalyst was dispersed in ethanol solution, and the washed catalyst and ethanol were mixed at a mass-volume ratio of 1:100 (g / mL). While stirring for 1 h, 10% by volume of a 0.05 M NaBH4 solution was added. Filter again, wash the catalyst with ultrapure water, dry at 60 °C for 12 h, and heat at 200 °C under a hydrogen atmosphere for 30 min to obtain the activated catalyst.

[0046] Comparative Example 1 Support pretreatment: Weigh 50 g of activated carbon, disperse the activated carbon in 250 ml of ultrapure water, add 21.06 g of copper chloride, maintain stirring and dispersion for 24 h, and after solid-liquid separation, dry at 100 °C to obtain a copper-loaded activated carbon support; Active component loading: Weigh 10 g of the support obtained in step (1) and disperse it again in 150 ml of ultrapure water. Measure 18.8 ml of 0.1 mol / L chloroplatinic acid solution and add it dropwise to the support solution. After the addition, keep stirring and dispersing, and dry at 110 °C for 8 h; Sintering treatment: The dried product was sintered in a hydrogen atmosphere at a sintering temperature of 250 °C for 2 h. Finally, the catalyst Cat-2 was obtained after washing. The synthesis method of 2,2'-dichlorohydrazo-benzene in Example 2 was used to repeatedly apply the catalyst Cat-2 until the yield of 2,2'-dichlorohydrazo-benzene reached below 55%. The deactivated catalyst obtained in that application was numbered Cat-2D.

[0047] Comparative Example 2 Support pretreatment: Weigh 50 g of activated carbon, disperse the activated carbon in 250 ml of ultrapure water, add 14.5 g of potassium ferrocyanide, maintain stirring and dispersion for 24 h, and after solid-liquid separation, dry it at 100 °C to obtain an iron-loaded activated carbon support; Active component loading: Weigh 10 g of the support obtained in step (1) and disperse it again in 150 ml of ultrapure water. Measure 18.8 ml of 0.1 mol / L chloroplatinic acid solution and add it dropwise to the support solution. After the addition, maintain stirring and dispersion, and dry it at 110 °C for 8 h; Sintering treatment: The dried product was sintered in a hydrogen atmosphere at a sintering temperature of 250 °C for 2 h. Finally, the catalyst Cat-3 was obtained after washing. The synthesis method of 2,2'-dichlorohydrazo-benzene in Example 2 was used to repeatedly apply the catalyst Cat-3 until the yield of 2,2'-dichlorohydrazo-benzene reached below 55%. The deactivated catalyst obtained in that application was numbered Cat-3D.

[0048] Comparative Example 3 Support pretreatment: Weigh 50 g of activated carbon, disperse the activated carbon in 250 ml of ultrapure water, maintain stirring and dispersion for 24 h, and after solid-liquid separation, dry it at 100 °C to obtain an activated carbon support; Active component loading: Weigh 10 g of the support obtained in step (1) and disperse it again in 150 ml of ultrapure water. Measure 18.8 ml of 0.1 mol / L chloroplatinic acid solution and add it dropwise to the support solution. After the addition, maintain stirring and dispersion, and dry it at 110 °C for 8 h; Sintering treatment: The dried product was sintered in a hydrogen atmosphere at a sintering temperature of 250 °C for 2 h. Finally, the catalyst Cat-4 was obtained after washing. The synthesis method of 2,2'-dichlorohydrazo-benzene in Example 2 was used to repeatedly apply the catalyst Cat-4 until the yield of 2,2'-dichlorohydrazo-benzene reached below 55%. The deactivated catalyst obtained in that application was numbered Cat-4D.

[0049] Comparative Example 4 Support pretreatment: Weigh 50 g of alumina, disperse the alumina in 250 ml of ultrapure water, add 29.04 g of ferric chloride, maintain stirring and dispersion for 24 h, and after solid-liquid separation, dry at 100 °C to obtain an iron-loaded alumina support; Active component loading: Weigh 10 g of the support obtained in step (1) and disperse it again in 150 ml of ultrapure water. Measure 18.8 ml of 0.1 mol / L chloroplatinic acid solution and add it dropwise to the support solution. After the addition, maintain stirring and dispersion, and dry at 110 °C for 8 h; Sintering treatment: Sinter the dried product in a hydrogen atmosphere at a sintering temperature of 250 °C for 2 h. Finally, wash to obtain catalyst Cat-5. Use the synthesis method of 2,2'-dichlorohydrazo-benzene in Example 2 to reuse catalyst Cat-5 multiple times until the yield of 2,2'-dichlorohydrazo-benzene reaches less than 55%. Number the catalyst obtained in the current reuse as Cat-5D.

[0050] Example 5 As shown in Table 2, 0.15 g of catalysts Cat-1 to Cat-5 are mixed with 75 g of o-chloronitrobenzene, 65 ml of toluene, and 61 ml of 16% sodium hydroxide solution. Add 0.20 g of 1,4-naphthoquinone and 0.20 g of sodium dodecylbenzenesulfonate. Replace hydrogen 3 times in a high-pressure reaction kettle, heat up to 70 °C, introduce 1.0 MPa of hydrogen, stabilize the temperature at 80 °C, and react under hydrogen pressure for 2 h 50 min. Separate and purify to obtain 2,2'-dichlorohydrazo-benzene. Reuse the catalyst multiple times, take samples for detection, record the yield A1 of 2,2'-dichlorohydrazo-benzene when the catalyst is used for the first time, and record the reuse times T1 of the catalyst when the yield of 2,2'-dichlorohydrazo-benzene decreases to 90% of A1. Make groups 1 to 5, and the results are shown in Table 1: Table 1 In Table 1, A1% is the yield of 2,2'-dichlorohydrazo-benzene when the catalyst is used for the first time (first yield); B1% is the yield of impurity o-chloroaniline when the catalyst is used for the first time; T1 is the reuse times of the catalyst when the yield of 2,2'-dichlorohydrazo-benzene decreases to less than 90% of the first yield (A1%); C2% is the yield of 2,2'-dichlorohydrazo-benzene when the catalyst is reused for the T1th time; D2% is the yield of o-chloroaniline when the catalyst is reused for the T1th time. The Pt-Fe / C catalyst Cat-1 of the present invention has a higher first yield A1% of 2,2'-dichlorohydrazo-benzene compared to Cat2~Cat-5 prepared by other catalyst preparation methods. More importantly, in the case of multiple reuses, the activity decay of the catalyst is slow, and the by-product o-chloroaniline does not increase significantly. Compared with the preparation of other catalysts Cat2~Cat-5, the cost of the noble metal catalyst is significantly reduced.

[0051] Example 5 Using the activation method of Example 4, the deactivated catalysts Cat-1D to Cat-5D were activated to obtain the activated catalysts Cat-1DR to Cat-5DR.

[0052] 0.15 g of the catalysts Cat-1DR to Cat-5DR were respectively put into a reaction system of 75 g of o-chloronitrobenzene, 65 ml of toluene and 61 ml of 16% sodium hydroxide solution, and then 0.20 g of 1,4-naphthoquinone and 0.20 g of sodium dodecylbenzenesulfonate were added. The hydrogen was replaced 3 times in a high-pressure resistant reactor, the temperature was raised to 70 °C, 1.0 MPa of hydrogen was introduced, the temperature was stabilized at 80 °C, and the reaction was carried out for 2 h 50 min under hydrogen pressure. 2,2'-Dichlorohydrazobenzene was separated and purified, and the catalysts were reused multiple times. Samples were taken to detect the first yield % of 2,2'-dichlorohydrazobenzene and the first content % of the impurity o-chloroaniline. The catalysts were reused multiple times, samples were taken for detection, and when the catalysts were used for the first time, the yield A2 of 2,2'-dichlorohydrazobenzene was recorded, and the number of reuse times T2 of the catalyst when the yield of 2,2'-dichlorohydrazobenzene decreased to 90% of A2 was recorded, obtaining Groups 6 to 10.

[0053] Table 2 In Table 2, A2% is the yield of 2,2'-dichlorohydrazobenzene (first yield) when the activated catalyst is used for the first time; B2% is the yield of the impurity o-chloroaniline when the activated catalyst is used for the first time; T2 is the number of reuse times of the activated catalyst when the yield of 2,2'-dichlorohydrazobenzene decreases to less than 90% of the first yield (A2); C2% is the yield of 2,2'-dichlorohydrazobenzene when the activated catalyst is reused for the T2th time; D2% is the yield of o-chloroaniline when the activated catalyst is reused for the T2th time. After the catalyst is deactivated, it is secondarily activated to obtain the catalysts Cat-1DR to Cat-5DR. Compared with Cat-2DR to Cat-5DR, the catalyst Cat-1DR still maintains a good effect after secondary activation, increasing the service life.

[0054] Comparative Example 5 0.15 g of the catalyst Cat-1 prepared in Example 1 was put into a reaction system of 75 g of o-chloronitrobenzene and 65 ml of toluene, 0.45 g of 1,4-naphthoquinone and 0.235 g of sodium dodecylbenzenesulfonate were added, the hydrogen was replaced 3 times in a high-pressure resistant reactor, the temperature was raised to 70 °C, 1.0 MPa of hydrogen was introduced, the temperature was stabilized at 80 °C, and the reaction was carried out for 2 h 50 min under hydrogen pressure. 2,2'-Dichlorohydrazobenzene was separated and purified.

[0055] The catalyst Cat-1 was reused multiple times in this synthesis method until the yield of 2,2'-dichlorohydrazobenzene reached less than 55%. The inactivated catalyst after reuse was numbered Cat-1D-5, and Group 11 was obtained.

[0056] Comparative Example 5-1 The used catalyst Cat-1D-5 was activated using the method of Example 4 to obtain the activated catalyst Cat-1DR-5.

[0057] The catalyst Cat-1DR-5 was reused multiple times in the synthesis method of 2,2'-dichlorohydrazobenzene in Comparative Example 5 until the yield of 2,2'-dichlorohydrazobenzene was 90% of that when the catalyst Cat-1DR-5 was first used. The number of times was recorded, and Group 12 was obtained.

[0058] Comparative Example 6 0.15 g of the catalyst Cat-1 prepared in Example 1 was put into a reaction system of 75 g of o-chloronitrobenzene, 65 ml of methanol and 61 ml of 16% sodium hydroxide solution. 0.45 g of 1,4-naphthoquinone and 0.235 g of sodium dodecylbenzenesulfonate were added. Hydrogen was replaced 3 times in a high-pressure resistant reactor, the temperature was raised to 70 °C, 1.0 MPa of hydrogen was introduced, the temperature was stabilized at 80 °C, and the reaction was carried out for 2 h 50 min under hydrogen pressure. 2,2'-Dichlorohydrazobenzene was obtained by separation and purification.

[0059] The catalyst Cat-1 was reused multiple times in this synthesis method until the yield of 2,2'-dichlorohydrazobenzene reached less than 55%. The inactivated catalyst after reuse was numbered Cat-1D-6, and Group 13 was obtained.

[0060] Comparative Example 6-1 The used catalyst Cat-1D-6 was activated using the method of Example 4 to obtain the activated catalyst Cat-1DR-6.

[0061] The catalyst Cat-1DR-6 was reused multiple times in the synthesis method of 2,2'-dichlorohydrazobenzene in Comparative Example 6 until the yield of 2,2'-dichlorohydrazobenzene was 90% of that when the catalyst Cat-1DR-6 was first used. The number of times was recorded, and Group 14 was obtained.

[0062] Comparative Example 7 0.15 g of the catalyst Cat-1 prepared in Example 1 was put into a reaction system of 75 g of o-chloronitrobenzene, 65 ml of toluene and 61 ml of 16% sodium hydroxide solution, and only 0.235 g of sodium dodecylbenzenesulfonate was added. The hydrogen in the high-pressure resistant reactor was replaced 3 times, the temperature was raised to 70 °C, 1.0 MPa of hydrogen was introduced, the temperature was stabilized at 80 °C, and the reaction was carried out for 2 h 50 min under hydrogen pressure. After separation and purification, 2,2'-dichlorohydrazo-benzene was obtained.

[0063] The catalyst Cat-1 was reused in this synthesis method for multiple times until the yield of 2,2'-dichlorohydrazo-benzene reached less than 55%, and Group 15 was obtained. The deactivated catalyst after reuse was numbered Cat-1D-7.

[0064] Comparative Example 7-1 The used catalyst Cat-1D-7 was activated by the method of Example 4 to obtain the activated catalyst Cat-1DR-7.

[0065] The catalyst Cat-1DR-7 was reused in the synthesis method of Comparative Example 7 for 2,2'-dichlorohydrazo-benzene until the yield of 2,2'-dichlorohydrazo-benzene reached 90% of that when the catalyst Cat-1DR-7 was first used. The number of times was recorded to obtain Group 16.

[0066] Comparative Example 8 0.15 g of the catalyst Cat-1 prepared in Example 1 was put into a reaction system of 75 g of o-chloronitrobenzene, 65 ml of toluene and 61 ml of 16% sodium hydroxide solution, and only 0.45 g of 1,4-naphthoquinone was added. The hydrogen in the high-pressure resistant reactor was replaced 3 times, the temperature was raised to 70 °C, 1.0 MPa of hydrogen was introduced, the temperature was stabilized at 80 °C, and the reaction was carried out for 2 h 50 min under hydrogen pressure. After separation and purification, 2,2'-dichlorohydrazo-benzene was obtained.

[0067] The catalyst was reused in this synthesis method for multiple times until the yield of 2,2'-dichlorohydrazo-benzene reached less than 55%. The deactivated catalyst after reuse was numbered Cat-1D-8, and Group 17 was obtained.

[0068] Comparative Example 8-1 The used catalyst Cat-1D-8 was activated by the method of Example 4 to obtain the activated catalyst Cat-1DR-8.

[0069] The catalyst Cat-1DR-8 was reused in the synthesis method of Comparative Example 8 for 2,2'-dichlorohydrazo-benzene until the yield of 2,2'-dichlorohydrazo-benzene reached 90% of that when the catalyst Cat-1DR-8 was first used. The number of times was recorded to obtain Group 18.

[0070] Example 6 The test results of recording groups 11 to 18 are shown in Table 3 Table 3 In Table 3, the yield of 2,2'-dichlorohydrazo-benzene at the first use of the catalyst is A3% (the first yield), the yield of the impurity o-chloroaniline at the first use of the catalyst is B3%, the number of times the catalyst can be reused when the yield of 2,2'-dichlorohydrazo-benzene is reduced to less than 90% of the first yield is T3, the yield of 2,2'-dichlorohydrazo-benzene at the T3th reuse of the catalyst is C3%, and the yield of o-chloroaniline at the T3th reuse of the catalyst is D3%. Groups 11 to 18 tested the performance of the catalyst Cat-1 under multiple reaction conditions and its performance after secondary activation. The catalyst Cat-1 in combination with the reaction feed system of the present invention can achieve a better primary catalytic effect and meet the requirements of secondary activation in production.

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a Pt-Fe / C catalyst, comprising: Step 1: Dispersing a carrier carbon in water, then adding a soluble iron salt, separating, and drying to obtain an iron-loaded carbon carrier; Step 2: Redispersing the iron-loaded carbon carrier in water, adding a platinum salt solution, mixing evenly, and drying to obtain a dried product; Step 3: Heating and sintering the dried product in a hydrogen atmosphere to obtain a Pt-Fe / C catalyst.

2. The preparation method of the Pt-Fe / C catalyst according to claim 1, characterized in that, In the said Step 1, 150 - 250 g of the carrier carbon is dispersed in each 1 L of water, preferably 200 g; and / or, in the said Step 1, the iron salt is a soluble iron salt; and / or, the said soluble iron salt is one of ferric chloride, ferrous chloride, iron nitrate, and iron sulfate; and / or, in the said Step 1, based on iron, the feeding mass ratio of the soluble iron salt to the carrier carbon is (4 - 6):1; and / or, the said carrier carbon is one or more of activated carbon, carbon fiber, mesoporous carbon, and carbon nanotubes; and / or, the drying temperature in the said Step 1 is 80 - 120 °C, preferably 100 °C.

3. The preparation method of the Pt-Fe / C catalyst according to any one of claims 1 or 2, characterized in that, In the said Step 2, the feeding mass of the iron-loaded carbon carrier dispersed in each 1 L of water is 150 - 250 g, preferably 150 g; and / or, in the said Step 2, the molar amount of the platinum salt added to each 1 L of water is 10 - 15 mmol, preferably 12.5 mmol; and / or, in the said Step 2, the added platinum salt is any one or a mixture of platinum chloride, chloroplatinic acid, and platinum nitrate; and / or, in the said Step 2, the added platinum salt solution is an aqueous solution of the platinum salt; and / or, the addition method of the platinum salt solution is dropwise addition; and / or, after mixing evenly in the said Step 2, solid-liquid separation is also carried out before drying; and / or, the drying temperature is 100 - 120 °C; and / or, the drying time is 7 - 9 h.

4. The preparation method of the Pt-Fe / C catalyst according to any one of claims 1 to 3, characterized in that, In the said Step 3, the heating and sintering temperature is 200 - 300 °C, preferably 250 °C, and / or, in the said Step 3, the sintering temperature is 1.5 - 2.5 h, preferably 2 h.

5. A Pt-Fe / C catalyst obtained by the preparation method according to any one of claims 1 to 4.

6. A synthesis method of 2,2'-dichlorohydrazo benzene, comprising: Mixing the Pt-Fe / C catalyst according to claim 5 with o-chloronitrobenzene, an organic solvent, and an alkali solution, adding a first auxiliary agent and a second auxiliary agent, heating to a first predetermined temperature, replacing the gas atmosphere with hydrogen, stabilizing the temperature at a second predetermined temperature, pressurizing, and reacting to obtain 2,2'-dichlorohydrazo benzene; 。 7. The synthesis method of 2,2'-dichlorohydrazobenzene according to claim 6, characterized in that, The feeding mass ratio of the catalyst to o-chloronitrobenzene is 0.1 - 5.0 wt%, and / or, the said organic solvent is selected from one or more of toluene, acetonitrile, methanol, ethanol, isopropanol, and chloroform, the said first auxiliary agent is selected from one or more of 1,4-naphthoquinone and 1,2-naphthoquinone, and / or, the said second auxiliary agent is selected from emulsifiers, and the emulsifiers are selected from any one or a combination of nonylphenol polyoxyethylene ether, sodium dodecylbenzenesulfonate, sodium lauroyl sarcosinate, and polyoxyethylene fatty alcohol ether.

8. The synthesis method of 2,2'-dichlorohydrazobenzene according to any one of claims 6 or 7, characterized in that, The base is selected from one or more of sodium hydroxide, potassium hydroxide, and triethylamine; and / or, the base solution is an aqueous solution of the base; and / or, the mass concentration fraction of the base solution is 16-20%.

9. The synthesis method of 2,2'-dichlorohydrazobenzene according to any one of claims 6 to 8, characterized in that, In each 1 L of the organic solvent, the feeding mass of the first auxiliary agent is 5-8 g; and / or, in each 1 L of the organic solvent, the feeding mass of the second auxiliary agent is 2-4 g.

10. The synthesis method of 2,2'-dichlorohydrazo-benzene according to any one of claims 6 to 9, characterized in that, The first temperature is 65-75 °C; and / or, the second temperature is 75-85 °C, and / or, the pressure of hydrogen pressurization is 0.8-1.2 Mpa.

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