Catalyst for decarbonylation and carbonylation coupling reaction, preparation method thereof and application thereof

Abstract

The present invention discloses a catalyst for the coupling reaction of decarbonylation and carbonylation, its preparation method and application. The catalyst includes a carrier, palladium and phosphate. The preparation method of the catalyst includes: (1) loading a palladium precursor onto the carrier by an impregnation method, drying and reducing to obtain a catalyst intermediate; (2) impregnating the catalyst intermediate obtained in step (1) into an impregnating solution containing phosphate, and drying and calcining under an inert atmosphere to obtain the catalyst. The catalyst of the present invention is a new bifunctional catalyst, which can effectively promote the coupling reaction of decarbonylation and carbonylation, realize the self-production and self-use of CO, improve the atom utilization rate, and can enhance the bifunctional catalytic activity, increase the production of dimethyl carbonate and methyl 3-pentenoate, and extend the service life of the catalyst and save costs when used in the coupling reaction of preparing dimethyl carbonate from dimethyl oxalate and preparing methyl 3-pentenoate from 1,3-butadiene.

Description

Technical Field

[0001] The present invention relates to the field of catalytic materials, and particularly to a catalyst for the coupling reaction of decarbonylation and carbonylation, a preparation method thereof, and an application in the co-production of methyl 3-pentenoate and dimethyl carbonate. Background Art

[0002] Methyl 3-pentenoate is an important intermediate for the preparation of adipic acid, and the latter is a raw material for nylon 66. Traditional methods include the oxidation of KA oil with nitric acid or the hydrocyanation of butadiene, etc., which have problems such as equipment corrosion, high raw material toxicity, and large environmental pollution. Wang et al. (Chin. J. Catal., 2010, 31: 1044-1048) studied and showed that a catalyst system composed of palladium acetate, bidentate phosphine ligand 2,2'-bis(diphenylphosphino)biphenyl ether, and organic acid promoter p-toluic acid has high catalytic activity for the synthesis of methyl 3-pentenoate by the carboxylation reaction of 1,3-butadiene. At present, there is a certain feasibility in the preparation of methyl 3-pentenoate by the carboxylation route of 1,3-butadiene, but its research still remains on homogeneous catalysts, and the industrialization is difficult.

[0003] Dimethyl carbonate (DMC) is a chemical raw material with low toxicity, excellent environmental protection performance, and wide uses. It is also an important organic synthesis intermediate. Its molecular structure contains functional groups such as carbonyl, methyl, and methoxy, and has various reaction properties. It has the characteristics of safe use, convenience, less pollution, and easy transportation in production. Especially, the rapid development of lithium-ion batteries has also increased the demand for dimethyl carbonate. In addition, with the continuous decline in the price of ethylene glycol, the decarbonylation of dimethyl oxalate (DMO), an intermediate in the coal-to-ethylene glycol process, to prepare high-value-added dimethyl carbonate has certain economic benefits, and has environmental protection advantages and cost advantages.

[0004] There is no reported method for the co-production of methyl 3-pentenoate and dimethyl carbonate in the prior art. Summary of the Invention

[0005] The present invention provides a catalyst for the coupling reaction of decarbonylation and carbonylation, a preparation method thereof, and an application in the co-production of methyl 3-pentenoate and dimethyl carbonate. The catalyst of the present invention is a new bifunctional catalyst, which can effectively promote the coupling reaction of decarbonylation and carbonylation, realize the self-production and self-use of CO, improve the atom utilization rate. When used in the reaction of preparing dimethyl carbonate from dimethyl oxalate and the reaction of preparing methyl 3-pentenoate from 1,3-butadiene for coupling, it can enhance the bifunctional catalytic activity, increase the production of dimethyl carbonate and methyl 3-pentenoate, and extend the service life of the catalyst, saving costs.

[0006] In the first aspect of the present invention, a catalyst for the coupling reaction of decarbonylation and carbonylation is provided, wherein the catalyst comprises a carrier, palladium, and phosphate.

[0007] Further, in the catalyst, the carrier is selected from at least one of activated carbon, silica, magnesia, NaZSM-5 molecular sieve, manganese oxide, lead oxide, and α-aluminum oxide, and is preferably at least one of activated carbon, silica, and NaZSM-5 molecular sieve.

[0008] Further, in the catalyst, the phosphate is selected from alkali metal salts of phosphoric acid, and further selected from at least one of sodium phosphate, potassium phosphate, rubidium phosphate, and cesium phosphate.

[0009] Further, in the catalyst, based on the weight of the carrier, the mass content of palladium is 0.15% to 1.5%.

[0010] Further, in the catalyst, the molar ratio of phosphate (calculated as phosphorus) to palladium is 1 to 30, and preferably 5 to 20.

[0011] The second aspect of the present invention provides a method for preparing the above catalyst, including:

[0012] (1) By an impregnation method, a palladium precursor is loaded onto the carrier, and after drying and reduction, a catalyst intermediate is obtained;

[0013] (2) The catalyst intermediate obtained in step (1) is impregnated into an impregnating solution containing phosphate, and under an inert atmosphere, after drying and calcination, the catalyst is obtained.

[0014] Further, the carrier in step (1) is selected from at least one of activated carbon, silica, magnesia, NaZSM-5 molecular sieve, manganese oxide, lead oxide, and α-aluminum oxide, and is preferably at least one of activated carbon, silica, and NaZSM-5 molecular sieve. Preferably, the carrier can be pretreated before step (1), and the carrier pretreatment method is calcination in an inert atmosphere (such as nitrogen) at 300 to 500 °C (preferably 300 to 400 °C) for 1 to 3 h.

[0015] Further, the palladium precursor used in the impregnation method in step (1) is selected from at least one of palladium chloride, palladium acetate, palladium nitrate, palladium formate, and acetonitrile palladium chloride.

[0016] Further, the impregnation method in step (1) is preferably the equal-volume impregnation method, that is, the carrier is impregnated with a palladium-containing impregnating solution, and then dried and reduced to obtain a catalyst intermediate. The drying in step (1) is carried out in an oxygen-containing atmosphere (such as air), the drying temperature is 110 to 130 °C, and the drying time is 6 to 12 h. The reduction is carried out in a reducing atmosphere (such as hydrogen), and the reduction conditions are as follows: the reduction temperature is 200 to 400 °C, and the reduction time is 4 to 12 h.

[0017] Further, the phosphate in step (2) is selected from alkali metal salts of phosphoric acid, and further selected from at least one of sodium phosphate, potassium phosphate, rubidium phosphate, and cesium phosphate. The impregnation in step (2) preferably adopts the equal-volume impregnation method.

[0018] Further, the inert atmosphere in step (2) can be at least one of nitrogen, argon, and helium. The drying conditions are as follows: the drying temperature is 110-130 °C, and the drying time is 6-12 h. The calcination conditions are as follows: the calcination temperature is 300-600 °C, and the calcination time is 3-8 h.

[0019] The third aspect of the present invention provides a method for co-producing methyl 3-pentenoate and dimethyl carbonate. In this method, a fixed-bed reactor is used, and a mixed liquid of dimethyl oxalate and methanol is used as the liquid-phase raw material, and 1,3-butadiene is used as the gas-phase raw material. The process includes: the mixed liquid of dimethyl oxalate and methanol reacts with the gas-phase 1,3-butadiene in contact with the catalyst of the present invention to generate methyl 3-pentenoate and dimethyl carbonate.

[0020] Further, in the method, the molar ratio of dimethyl oxalate, methanol, and 1,3-butadiene is 0.5-2.0:0.5-3:1. Preferably, the molar ratio of dimethyl oxalate, methanol, and 1,3-butadiene is 0.8-1.2:1.5-2:1. Among them, when the molar ratio of dimethyl oxalate to 1,3-butadiene is less than 1, an appropriate amount of CO can be supplemented as needed to supply the CO required for the full reaction of 1,3-butadiene.

[0021] Further, the reaction conditions of the method are as follows: the reaction temperature is 140-200 °C, preferably 170-190 °C, and the mass space velocity of dimethyl oxalate is 0.5-4 h -1 , preferably 0.8-2.5 h -1 .

[0022] Further, the reaction product is subjected to gas-liquid separation by a gas-liquid separator. The obtained gas phase can be partially or fully recycled into the reactor. The obtained liquid phase is separated by a distillation column to obtain the products methyl 3-pentenoate and dimethyl carbonate, and the excess methanol can be recycled into the reactor.

[0023] Further, the reaction of the method is shown in formulas (1) and (2):

[0024]

[0025] (1) Decarbonylation reaction,

[0026]

[0027] (2) Carbonylation reaction.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. The method for co-producing methyl 3-pentenoate and dimethyl carbonate provided by the present invention. Specifically, CO generated in the reaction of preparing dimethyl carbonate from dimethyl oxalate is directly supplied to the alkoxycarbonylation reaction of 1,3-butadiene to prepare methyl 3-pentenoate, realizing the self-production and self-use of CO and improving the atom utilization rate.

[0030] 2. By using a catalyst loaded with palladium and phosphate, the present invention can enhance the activity of the palladium catalyst through palladium-phosphorus coordination without affecting the basicity of the phosphate. In addition, the formation of a coordination bond between palladium and phosphorus can play a role in fixing phosphorus, effectively reducing the loss of phosphate. In this way, the CO in-situ generated by the decarbonylation of dimethyl oxalate is directly supplied to the alkoxycarbonylation reaction of 1,3-butadiene, with higher efficiency, realizing the self-production and self-use of CO, thereby enhancing the bifunctional activity of the catalyst and prolonging the service life of the catalyst. Description of the Drawings

[0031] Figure 1 It is a schematic flow chart of the co-production of methyl 3-pentenoate and dimethyl carbonate of the present invention;

[0032] The description of the reference numerals in the drawings is as follows:

[0033] 1 - Carbonylation-decarbonylation coupling reactor, 2 - Flash tank, 3 - Distillation column. Detailed Embodiments

[0034] The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

[0035] In the present invention, the catalyst life is defined as: the number of days required when the conversion rate of dimethyl oxalate decreases to 90% of the initial conversion rate.

[0036] In the present invention, the conversion rate of dimethyl oxalate (%) = (mass of dimethyl oxalate in the raw material - mass of dimethyl oxalate in the product) / mass of dimethyl oxalate in the raw material × 100%;

[0037] The conversion rate of 1,3-butadiene (%) = (mass of 1,3-butadiene in the raw material - mass of 1,3-butadiene in the product) / mass of 1,3-butadiene in the raw material × 100%;

[0038] The selectivity of dimethyl carbonate DMC (%) = mass of dimethyl carbonate in the product / (mass of dimethyl oxalate in the raw material - mass of dimethyl oxalate in the product) × 100%;

[0039] Selectivity of methyl 3 - pentenoate (%) = mass of methyl 3 - pentenoate in the product / (mass of 1,3 - butadiene in the raw material - mass of 1,3 - butadiene in the product) × 100%.

[0040] In the present invention, 2 - P, 3 - P and 4 - P in each table respectively represent methyl 2 - pentenoate, methyl 3 - pentenoate and methyl 4 - pentenoate.

[0041] The present invention provides a method for co - producing methyl 3 - pentenoate and dimethyl carbonate, and its process schematic diagram is as Figure 1 . Liquid - phase dimethyl oxalate / methanol and gaseous 1,3 - butadiene enter the carbonylation - decarbonylation coupling reactor 1 simultaneously. Under the action of a bifunctional catalyst, dimethyl carbonate and pentenoic acid methyl ester are generated. The product passes through the flash tank 2. The gas phase can be partially or fully recycled and re - enter the carbonylation - decarbonylation coupling reactor 1 for reaction. The liquid phase enters the distillation column 3 for product separation. Dimethyl carbonate is obtained in the middle section of the column, methyl pentenoate is obtained at the bottom of the column, and methanol obtained at the top of the column can be recycled and enter the carbonylation - decarbonylation coupling reactor 1.

[0042] Example 1

[0043] 4.2 g of palladium acetate was dissolved in 70 g of water to obtain an impregnation solution, which was added to 100 g of activated carbon. After impregnation, it was dried at 110 °C for 2 h and reduced with hydrogen at 400 °C for 6 h to obtain an intermediate palladium - supported catalyst;

[0044] 39.8 g of potassium phosphate was dissolved in 70 g of water to obtain an impregnation solution, which was added to the above - mentioned catalyst intermediate. After impregnation, it was dried with nitrogen at 120 °C for 2 h and calcined with nitrogen at 400 °C for 5 h to obtain a bifunctional catalyst. Among them, based on the weight of the carrier, the mass content of Pd is 0.2 wt%, and the molar ratio of P / Pd is 10.

[0045] Catalyst evaluation: 15 g of the catalyst was filled into a fixed - bed reactor for pretreatment. The conditions were as follows: N 2 flow rate 200 mL / min, heated from room temperature to 180 °C in 60 min and maintained for 1 h. The dimethyl oxalate / methanol solution was pre - heated to 50 °C and pumped into the reactor at a mass space velocity of 1 h -1 . The molar ratio of 1,3 - butadiene to dimethyl oxalate was 1:1, and the molar ratio of methanol to 1,3 - butadiene was 2:1. The reaction temperature was 180 °C, and the reaction results are shown in Table 1.

[0046] Examples 2 - 8

[0047] Compared with Example 1, the preparation of the catalysts in Examples 2 - 8 only lies in using different carriers and different phosphates (specifically shown in Table 1), where the mass fraction of Pd is 0.2 wt% and the molar ratio of P / Pd is 10.

[0048] The catalyst evaluation method was the same as that in Example 1, and the results are shown in Table 1.

[0049] Table 1 Catalysts and evaluation results of each example

[0050]

[0051] Examples 9 - 12

[0052] Compared with Example 1, Examples 9 - 12 were different in that different P / Pd molar ratios were used (specifically shown in Table 2), and the mass fraction of Pd was 0.2 wt%.

[0053] The catalyst evaluation method was the same as that in Example 1, and the results are shown in Table 2.

[0054] Table 2 Catalysts and evaluation results of each example

[0055]

[0056] Example 13

[0057] Compared with Example 1, Example 13 was different in that a different mass fraction of Pd was used, and the P / Pd molar ratio was 10.

[0058] The catalyst evaluation method was the same as that in Example 1, and the results are shown in Table 3.

[0059] Table 3 Catalysts and evaluation results of each example

[0060]

[0061] Examples 14 - 21

[0062] The catalyst was prepared by the method of Example 1, where the mass fraction of Pd was 0.2 wt% and the P / Pd molar ratio was 10.

[0063] Compared with the catalyst evaluation method of Example 1, Examples 14 - 21 were only different in that different reaction conditions were used (specifically shown in Table 4), and the results are shown in Table 4.

[0064] Table 4 Catalysts and evaluation results of each example

[0065]

[0066] Comparative Example 1

[0067] Compared with Example 1, in Comparative Example 1, the method of Example 1 was changed to separate impregnation, that is, the carrier was separately impregnated into the palladium precursor solution and the phosphate solution to obtain catalyst a and catalyst b.

[0068] Catalyst evaluation: Compared with Example 1, Comparative Example 1 only involves physically mixing and filling 15 g of the above catalyst (catalyst a + catalyst b) into a fixed-bed reactor, and the rest is the same as in Example 1. The results are shown in Table 5.

[0069] Table 5 Evaluation results of the catalyst in Comparative Example 1

[0070]

[0071] As can be seen from Table 5, the two physically mixed catalysts do not show ideal activity in the two reactions. For the decarbonylation reaction, since the support loaded with phosphate becomes less and the total amount of phosphate remains unchanged, the residence time of the reaction raw materials will be reduced, so the activity decreases. For the carbonylation reaction, one reason is the same as that of the decarbonylation reaction, and another reason is that palladium cannot coordinate with phosphorus to form a more active complex. In contrast, using the catalyst of the present invention is beneficial to the coupling reaction and can improve the activity of the carbonylation reaction.

[0072] Comparative Example 2

[0073] Compared with Example 1, in Comparative Example 2, the method of Example 1 was changed to the one-step impregnation method, that is, impregnated into the mixed impregnation solution of palladium precursor and phosphate at one time for loading to finally obtain the catalyst.

[0074] Catalyst evaluation: Compared with Example 1, Comparative Example 2 only involves filling 15 g of the above catalyst into a fixed-bed reactor, and the rest is the same as in Example 1. The results are shown in Table 6.

[0075] Table 6 Evaluation results of the catalyst in Comparative Example 2

[0076]

[0077] As can be seen from Table 6, the palladium phosphate formed by one-step impregnation is insoluble in water, which easily causes the aggregation of active substances and the low activity of the catalyst.

[0078] Comparative Example 3

[0079] Compared with Example 1, in Comparative Example 3, only phosphate was loaded alone, and the loading amount was the same as in Example 1 to obtain the AC-K 3 PO 4 catalyst.

[0080] Catalyst evaluation: Fill 15 g of the above AC-K 3 PO 4 catalyst into a fixed-bed reactor, and the feed is dimethyl oxalate, which is pumped into the reactor at a mass space velocity of dimethyl oxalate of 1 h -1 The reaction temperature is 180 °C, and the reaction results are shown in Table 7.

[0081] Table 7 Evaluation results of the catalyst in Comparative Example 3

[0082]

[0083] As can be seen from Table 7, in terms of the initial conversion rate of dimethyl oxalate, the decarbonylation reaction activities in the separate decarbonylation reaction and the coupling reaction are the same. However, the lifespan of the separate decarbonylation reaction is only 15 days, while that of the coupling reaction in Example 1 reaches 60 days. The main reason is that the catalyst in Comparative Example 3 does not have the phosphorus-fixing effect of palladium, and phosphate slowly leaks during the reaction process, resulting in a rapid decline in activity.

Claims

1. A catalyst for the coupling reaction of decarbonylation and carbonylation, wherein, the catalyst comprises a support, palladium and phosphate, wherein palladium and phosphorus form a coordination bond; in the catalyst, the support is selected from at least one of activated carbon, silica, magnesia, NaZSM-5 molecular sieve, manganese oxide, and α-alumina, and the phosphate is selected from alkali metal salts of phosphoric acid; in the catalyst, based on the weight of the support, the mass content of palladium is 0.15% - 1.5%; in the catalyst, the molar ratio of phosphate (calculated as phosphorus) to palladium is 1 - 30.

2. The catalyst according to claim 1, characterized in that, in the catalyst, the support is selected from at least one of activated carbon, silica, and NaZSM-5 molecular sieve.

3. The catalyst according to claim 1, characterized in that, the alkali metal salt of phosphoric acid is selected from at least one of sodium phosphate, potassium phosphate, rubidium phosphate, and cesium phosphate.

4. The catalyst according to claim 1, characterized in that, in the catalyst, the molar ratio of phosphate (calculated as phosphorus) to palladium is 5 - 20.

5. A preparation method of the catalyst according to any one of claims 1 - 4, comprising: (1) Loading a palladium precursor onto the support by an impregnation method, and obtaining a catalyst intermediate through drying and reduction; (2) Impregnating the catalyst intermediate obtained in step (1) into an impregnating solution containing phosphate, and obtaining the catalyst through drying and calcination under an inert atmosphere.

6. The preparation method according to claim 5, characterized in that, in step (1), the drying is carried out under an oxygen-containing atmosphere, the drying temperature is 110 - 130 °C, and the drying time is 6 - 12 h; the reduction is carried out under a reducing atmosphere, and the reduction conditions are as follows: the reduction temperature is 200 - 400 °C, and the reduction time is 4 - 12 h.

7. The preparation method according to claim 5, characterized in that, the inert atmosphere in step (2) is at least one of nitrogen, argon, and helium; the drying conditions are as follows: the drying temperature is 110 - 130 °C, and the drying time is 6 - 12 h; the calcination conditions are as follows: the calcination temperature is 300 - 600 °C, and the calcination time is 3 - 8 h.

8. A method for co-producing methyl 3-pentenoate and dimethyl carbonate, wherein, the method uses a fixed-bed reactor, takes a mixed solution of dimethyl oxalate and methanol as the liquid-phase raw material, and 1,3-butadiene as the gas-phase raw material. The process includes: contacting the mixed solution of dimethyl oxalate and methanol with the gas-phase 1,3-butadiene with the catalyst according to any one of claims 1 - 4 for reaction to generate methyl 3-pentenoate and dimethyl carbonate.

9. The method according to claim 8, characterized in that, in the method, the molar ratio of dimethyl oxalate, methanol, and 1,3-butadiene is 0.5 - 2:0.5 - 3:

1.

10. The method according to claim 8, characterized in that, in the method, the molar ratio of dimethyl oxalate, methanol, and 1,3-butadiene is 0.8 - 1.2:1.5 - 2:

1.

11. The method according to claim 8, characterized in that, The reaction conditions of the described method are as follows: the reaction temperature is 140 - 200 °C, and the mass space velocity of dimethyl oxalate is 0.5 - 4 h -1 .

12. The method according to claim 8, Characterized in that, The reaction conditions of the method are as follows: the reaction temperature is 170~190°C, and the mass space velocity of dimethyl oxalate is 0.8~2.5 h -1 .

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