A cobalt-based catalyst, a preparation method thereof, and a method for preparing cumene by hydrogenolysis of dimethylbenzyl alcohol

Abstract

This invention discloses a cobalt-based catalyst and its preparation method, as well as a method for preparing cumene by hydrogenolysis of dimethylbenzyl alcohol. The catalyst comprises an active component Co, doped with metal M and metal Nb, wherein metal M is selected from one or more of Ti, Cu, Ni, W, etc. This catalyst can be used for the hydrogenolysis of dimethylbenzyl alcohol to prepare cumene. The catalyst provided by this invention can improve the feed conversion rate and product selectivity in the hydrogenolysis of dimethylbenzyl alcohol to cumene at lower reaction pressures and lower reaction temperatures.

Description

Technical Field

[0001] This invention relates to the field of organic chemical engineering, specifically to a cobalt-based catalyst and its preparation method, and a method for preparing cumene by hydrogenolysis of dimethylbenzyl alcohol. Background Technology

[0002] Propylene oxide (PO) is an important propylene derivative, a colorless ether liquid with a low boiling point and flammability. Its main uses are in the production of polyether polyols and propylene glycol (PG), and it can also be used to prepare propylene glycol ethers, flame retardants, nonionic surfactants, and plasticizers. Polyether polyols and nonionic surfactants are widely used in the petrochemical, pesticide, and daily chemical industries. Therefore, it is a very important organic compound raw material.

[0003] Dimethylbenzyl alcohol is a white prismatic crystal that is readily soluble in organic solvents such as diethyl ether, ethyl acetate, benzene, and ethanol, but poorly soluble in water. It is an important raw material for the manufacture of fragrances and flavorings, and is also an important chemical intermediate.

[0004] The cumene peroxide (CHP) process is a new process for preparing PO. This process mainly includes three steps: oxidation of cumene to CHP, epoxidation of propylene and CHP to PO, and hydrogenolysis of dimethyl benzyl alcohol (DMBA) to cumene. The hydrogenolysis of DMBA to cumene is mainly to realize the recycling of cumene.

[0005] The catalysts used in hydrogenolysis reactions typically employ two systems: Cu-based and Pd-based catalysts. Patent CN 114425328 B discloses an α,α-dimethylbenzyl alcohol hydrogenolysis catalyst, its preparation method, and its application. This catalyst includes a support, Pd, and Si elements. Under the action of the catalyst, the benzyl alcohol conversion rate reaches over 99.8%, and the selectivity for cumene is over 99.5%. Although this catalyst exhibits good activity, it contains precious metal elements, which increases the cost and makes it susceptible to poisoning and deactivation.

[0006] Patent CN 101992086 B discloses a catalyst for the hydrogenation of cumene peroxide to α,α-dimethylbenzyl alcohol and its preparation method. The catalyst uses alumina or silica as a support and Pd noble metal catalyst as the active component. Under the set reaction conditions, the conversion rate of dimethylbenzyl alcohol is greater than 99.0%. Although the long-term operation effect is good, the impregnation method is prone to uneven loading of active metal components and agglomeration of active metal.

[0007] Patent CN 102218326 B discloses a Mn-based oxide catalyst for the decomposition of CHP to prepare cumene. The catalyst has good acidity distribution and redox properties, but concentrated nitric acid needs to be introduced during the preparation process to adjust the pH to a low level, which can easily cause environmental pollution.

[0008] Therefore, preparing a green catalyst that can improve the feed conversion rate and product selectivity in the hydrogenolysis of dimethylbenzyl alcohol to cumene under mild conditions, especially at lower reaction pressures and temperatures, remains an urgent problem to be solved. Summary of the Invention

[0009] To address the problems existing in the prior art, the present invention aims to provide a cobalt-based catalyst that can improve the feed conversion rate and product selectivity in the hydrogenolysis of dimethylbenzyl alcohol to cumene at lower reaction pressures and temperatures.

[0010] Another object of the present invention is to provide a method for preparing such a catalyst.

[0011] Another object of the present invention is to provide a method for using such a catalyst to produce cumene via hydrogenolysis of dimethylbenzyl alcohol.

[0012] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0013] A Co-based catalyst includes an active component Co, a doped metal M, and a metal Nb, wherein the metal M is selected from one or more of Ti, Cu, Ni, W, etc.

[0014] The molar ratio of Co, Nb and metal M is 2:0.25-0.6:0.3-0.8; preferably 2:0.35-0.55:0.5-0.7.

[0015] The catalyst of this application incorporates Nb to adjust acidity and adds metals such as Ti, Cu, Ni, and W to lower the cobalt oxide reduction temperature, which can improve the selectivity of cumene and extend the catalyst's lifespan.

[0016] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst, wherein solid powder compounds containing Co, Nb, and metal M are mixed, a dispersant is added and stirred into a paste, and then dried and calcined to prepare the shaped product.

[0017] In one specific embodiment of the present invention, the Co-containing compound is selected from one or more of cobalt oxide, cobalt nitrate, and cobalt oxalate; the Nb-containing compound is derived from one or more of niobium oxalate and niobic acid.

[0018] The Ti-containing compounds are derived from one or more of metatitanic acid and titanium oxide; the Cu-containing compounds are derived from one or more of copper nitrate and basic copper carbonate; the Ni-containing compounds are derived from one or more of nickel nitrate, basic nickel carbonate, and nickel acetate; and the W-containing compounds are derived from one or more of tungsten oxide and ammonium metatungstate.

[0019] In one specific embodiment of the present invention, the dispersant is any one or more of DMF, methanol, and acetonitrile.

[0020] Preferably, the amount of dispersant added is 0.3-0.6 times the total mass of the metal compound converted into oxides, for example, 0.3 times, 0.35 times, 0.4 times, 0.45 times, 0.5 times, 0.6 times, etc., more preferably 0.4-0.5 times.

[0021] In one specific embodiment of the present invention, the stirring process temperature is 20-45℃, for example 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, and the stirring time is 2-4h, for example 2h, 2.5h, 3h, 3.5h, 4h.

[0022] In one specific embodiment of the present invention, the paste is first ground and then dried, and the grinding time is controlled at 3-6 hours, for example 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, and 6 hours.

[0023] In a specific embodiment of the present invention, the drying temperature is controlled at 10-30°C below the boiling point of the selected dispersant. For example, when the dispersant is methanol, the drying process temperature is controlled at 35-55°C; when the dispersant is DMF, the drying process temperature is controlled at 123-143°C; and when the dispersant is acetonitrile, the drying process temperature is controlled at 56-76°C. The drying time is controlled at 1-3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours.

[0024] In one specific embodiment of the present invention, the roasting process temperature is controlled at 300-700℃, for example 300℃, 400℃, 500℃, 600℃, 700℃; the roasting process time is controlled at 3-8h, for example 3h, 4h, 5h, 6h, 7h, 8h.

[0025] Thirdly, the present invention also provides a method for preparing cumene by hydrogenolysis of dimethylbenzyl alcohol, wherein the catalyst described in the present invention is reduced and activated under a hydrogen atmosphere, and then dimethylbenzyl alcohol raw material is introduced under a hydrogen atmosphere to undergo a hydrogenolysis reaction to obtain cumene.

[0026] In one specific embodiment of the present invention, the reduction activation temperature under a hydrogen atmosphere is 600-900℃, for example 600℃, 700℃, 800℃, 900℃, the activation pressure is 3-5MPaG, for example 3MPa, 3.5MPa, 4MPa, 4.5MPa, 5MPa, and the activation time is 3-9h, for example 3h, 4h, 5h, 6h, 7h, 8h, 9h.

[0027] The activation conditions are: temperature 600-900℃, pressure 3-5MPaG, and time 3-9h.

[0028] Cobalt compounds are reduced to elemental cobalt by hydrogen gas.

[0029] In one specific embodiment of the present invention, the hydrogenolysis reaction temperature is 130-180°C, for example 130°C, 140°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C; the reaction pressure is 1.6-2.0 MPaG, for example 1.6 MPaG, 1.7 MPaG, 1.8 MPaG, 1.9 MPaG, 2.0 MPaG;

[0030] In one specific embodiment of the present invention, the liquid time space velocity is 1-4 h. -1 For example, 1h -1 2h -1 3h -1 4h -1 ;

[0031] In one specific embodiment of the present invention, the hydrogen-to-alcohol volume ratio (i.e., hydrogen volume: dimethylbenzyl alcohol volume) is 8-12, for example 8, 9, 10, 11, 12.

[0032] The unsupported cobalt-based catalyst provided by this invention, when used in the hydrogenolysis of dimethylbenzyl alcohol to prepare cumene, has the following advantages compared to existing technologies:

[0033] (1) The method of preparing catalyst by ball milling is simple, and the prepared catalyst does not contain a support, has many active sites, is not easily deactivated, and the cost of non-precious metal catalysts is low and they are more resistant to poisoning.

[0034] (2) The addition of Nb can adjust the acidity of the catalyst, resulting in high selectivity for cumene and fewer byproducts;

[0035] (3) The introduction of the third metal M can effectively reduce the reduction temperature of cobalt oxide and avoid the sintering of the catalyst active components caused by excessively high calcination temperature.

[0036] (4) Co-based catalysts have high hydrogenolysis activity, which can effectively reduce the temperature and pressure of dimethyl benzyl alcohol hydrogenolysis to prepare cumene, thus reducing equipment costs. Detailed Implementation

[0037] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims of the present invention.

[0038] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0039] Preparation Example 1

[0040] (1) 29.4g of cobalt oxalate, 26.9g of niobium oxalate and 4.9g of metatitanic acid were added to 8.5g of DMF. In the preparation of the above catalyst, the molar ratio of Co, Nb and Ti was 2:0.5:0.5. The amount of DMF added was 0.5 times the total mass of the above metal compounds after conversion into oxides. After adding DMF, the mixture was stirred at 30°C for 3h to obtain a paste.

[0041] (2) Grind the paste obtained in step (1) for 4 hours, and then dry it at 135°C for 2 hours.

[0042] (3) The dried material obtained in step (2) was calcined at 500°C for 3 hours to obtain the catalyst.

[0043] Preparation Example 2

[0044] (1) 29.4g of cobalt oxalate, 26.9g of niobium oxalate and 9.4g of copper nitrate were added to 6.8g of DMF. In the preparation of the above catalyst, the molar ratio of Co, Nb and Cu was 2:0.5:0.5. The amount of DMF added was 0.4 times the total mass of the above metal compounds after conversion into oxides. After adding DMF, the mixture was stirred at 30°C for 3h to obtain a paste.

[0045] (2) Grind the paste obtained in step (1) for 4 hours, and then dry it at 135°C for 2 hours.

[0046] (3) The dried material obtained in step (2) was calcined at 500°C for 3 hours to obtain the catalyst.

[0047] Preparation Example 3

[0048] (1) 29.4g of cobalt oxalate, 13.5g of niobium oxalate and 15.0g of copper nitrate were added to 8.3g of DMF. In the preparation of the above catalyst, the molar ratio of Co, Nb and Cu was 2:0.25:0.8. The amount of DMF added was 0.5 times the total mass of the above metal compounds after conversion into oxides. After adding DMF, the mixture was stirred at 30°C for 3h to obtain a paste.

[0049] (2) Grind the paste obtained in step (1) for 4 hours, and then dry it at 135°C for 2 hours.

[0050] (3) The dried material obtained in step (2) was calcined at 500°C for 3 hours to obtain the catalyst. Preparation Example 4

[0051] (1) 29.4g of cobalt oxalate, 32.4g of niobium oxalate and 5.6g of copper nitrate were added to 6.6g of DMF. In the preparation of the above catalyst, the molar ratio of Co, Nb and Cu was 2:0.6:0.3. The amount of DMF added was 0.4 times the total mass of the above metal compounds after conversion into oxides. After adding DMF, the mixture was stirred at 30°C for 3h to obtain a paste.

[0052] (2) Grind the paste obtained in step (1) for 4 hours, and then dry it at 135°C for 2 hours.

[0053] (3) The dried material obtained in step (2) was calcined at 500°C for 3 hours to obtain the catalyst.

[0054] Preparation Example 5

[0055] (1) 29.4g of cobalt oxalate, 26.9g of niobium oxalate and 9.2g of nickel nitrate were added to 10.1g of DMF. In the preparation of the above catalyst, the molar ratio of Co, Nb and Ni was 2:0.5:0.5. The amount of DMF added was 0.6 times the total mass of the above metal compounds after conversion into oxides. After adding DMF, the mixture was stirred at 30°C for 3h to obtain a paste.

[0056] (2) Grind the paste obtained in step (1) for 4 hours, and then dry it at 135°C for 2 hours.

[0057] (3) The dried material obtained in step (2) was calcined at 500°C for 3 hours to obtain the catalyst.

[0058] Preparation Example 6

[0059] (1) 29.4g of cobalt oxalate, 26.9g of niobium oxalate and 11.6g of tungsten oxide were added to 12.3g of DMF. In the preparation of the above catalyst, the molar ratio of Co, Nb and W was 2:0.5:0.5. The amount of DMF added was 0.5 times the total mass of the above metal compounds after conversion into oxides. After adding DMF, the mixture was stirred at 30°C for 3h to obtain a paste.

[0060] (2) Grind the paste obtained in step (1) for 4 hours, and then dry it at 135°C for 2 hours.

[0061] (3) The dried material obtained in step (2) was calcined at 500°C for 3 hours to obtain the catalyst.

[0062] Preparation Example 7

[0063] (1) 29.4g of cobalt oxalate, 26.9g of niobium oxalate and 9.4g of copper nitrate were added to 8.5g of acetonitrile. In the preparation of the above catalyst, the molar ratio of Co, Nb and Cu was 2:0.5:0.5. The amount of acetonitrile added was 0.5 times the total mass of the above metal compounds after conversion into oxides. After adding acetonitrile, the mixture was stirred at 30°C for 3h to obtain a paste.

[0064] (2) Grind the paste obtained in step (1) for 4 hours, and then dry it at 70°C for 2 hours.

[0065] (3) The dried material obtained in step (2) was calcined at 500°C for 3 hours to obtain the catalyst.

[0066] Preparation of Comparative Example 1

[0067] (1) 29.4g of cobalt oxalate and 26.9g of niobium oxalate were added to 6.5g of DMF. In the preparation of the above catalyst, the molar ratio of Co to Nb was 2:0.5. The amount of DMF added was 0.5 times the total mass of the above metal compounds after conversion into oxides. After adding DMF, the mixture was stirred at 30°C for 3h to obtain a paste.

[0068] (2) Grind the paste obtained in step (1) for 4 hours, and then dry it at 135°C for 2 hours.

[0069] (3) The dried material obtained in step (2) was calcined at 500°C for 3 hours to obtain the catalyst.

[0070] Preparation of Comparative Example 2

[0071] (1) 29.4g of cobalt oxalate and 5.6g of copper nitrate were added to 6.6g of DMF. In the preparation of the above catalyst, the molar ratio of Co to Cu was 2:0.3. The amount of DMF added was 0.4 times the total mass of the above metal compounds after conversion into oxides. After adding DMF, the mixture was stirred at 30°C for 3h to obtain a paste.

[0072] (2) Grind the paste obtained in step (1) for 4 hours, and then dry it at 135°C for 2 hours.

[0073] (3) The dried material obtained in step (2) was calcined at 500°C for 3 hours to obtain the catalyst.

[0074] Example 1

[0075] The catalyst from Preparation Example 1 was reduced and activated at 600°C and 4 MPaG under a hydrogen atmosphere for 6 h. Subsequently, the temperature of the reaction system was adjusted to 150°C and the pressure to 1.8 MPaG, and dimethylbenzyl alcohol feedstock was introduced to a liquid hourly space velocity of 3 h⁻¹. -1The hydrogenohydrin was subjected to a hydrogenolysis reaction at a volume ratio of 10. Analysis of the products after the reaction showed that the conversion rate of dimethylbenzyl alcohol was 99.95% and the selectivity of cumene was 98.76%.

[0076] Example 2

[0077] The catalyst from Preparation Example 2 was reduced and activated at 600°C and 4 MPaG under a hydrogen atmosphere for 6 h. Subsequently, the temperature of the reaction system was adjusted to 150°C and the pressure to 1.8 MPaG, and dimethylbenzyl alcohol feedstock was introduced to a liquid hourly space velocity of 3 h⁻¹. -1 The hydrogenohydrin was subjected to a hydrogenolysis reaction at a volume ratio of 10. Analysis of the products after the reaction showed that the conversion rate of dimethylbenzyl alcohol was 99.91% and the selectivity of cumene was 98.89%.

[0078] Example 3

[0079] The catalyst from Preparation Example 3 was reduced and activated at 600°C and 4 MPaG under a hydrogen atmosphere for 6 h. Subsequently, the temperature of the reaction system was adjusted to 150°C and the pressure to 1.8 MPaG, and dimethylbenzyl alcohol feedstock was introduced to a liquid hourly space velocity of 3 h⁻¹. -1 The hydrogenohydrin was subjected to a hydrogenolysis reaction at a volume ratio of 10. Analysis of the products after the reaction showed that the conversion rate of dimethylbenzyl alcohol was 99.63% and the selectivity of cumene was 98.12%.

[0080] Example 4

[0081] The catalyst from Preparation Example 4 was reduced and activated at 600°C and 4 MPaG under a hydrogen atmosphere for 6 h. Subsequently, the temperature of the reaction system was adjusted to 150°C and the pressure to 1.8 MPaG, and dimethylbenzyl alcohol feedstock was introduced to a liquid hourly space velocity of 3 h⁻¹. -1 The hydrogenolysis reaction was carried out at a volume ratio of 10 to 10. Analysis of the products showed a dimethylbenzyl alcohol conversion of 99.75% and a cumene selectivity of 98.72%. Example 5

[0082] The catalyst from Preparation Example 5 was reduced and activated at 600°C and 4 MPaG under a hydrogen atmosphere for 6 h. Subsequently, the temperature of the reaction system was adjusted to 150°C and the pressure to 1.8 MPaG, and dimethylbenzyl alcohol feedstock was introduced to a liquid hourly space velocity of 3 h⁻¹. -1 The hydrogenohydrin was subjected to a hydrogenolysis reaction at a volume ratio of 10. Analysis of the products after the reaction showed that the conversion rate of dimethylbenzyl alcohol was 99.97% and the selectivity of cumene was 98.78%.

[0083] Example 6

[0084] The catalyst from Preparation Example 6 was reduced and activated at 600°C and 4 MPaG under a hydrogen atmosphere for 6 h. Subsequently, the temperature of the reaction system was adjusted to 150°C and the pressure to 1.8 MPaG, and dimethylbenzyl alcohol feedstock was introduced to a liquid hourly space velocity of 3 h⁻¹. -1The hydrogenohydrin was subjected to a hydrogenolysis reaction at a volume ratio of 10. Analysis of the products after the reaction showed that the conversion rate of dimethylbenzyl alcohol was 99.79% and the selectivity of cumene was 98.86%.

[0085] Example 7

[0086] The catalyst from Preparation Example 7 was reduced and activated at 600°C and 4 MPaG under a hydrogen atmosphere for 6 h. Subsequently, the temperature of the reaction system was adjusted to 150°C and the pressure to 1.8 MPaG, and dimethylbenzyl alcohol feedstock was introduced to a liquid hourly space velocity of 3 h⁻¹. -1 The hydrogenohydrin was subjected to a hydrogenolysis reaction at a volume ratio of 10. Analysis of the products after the reaction showed that the conversion rate of dimethylbenzyl alcohol was 99.90% and the selectivity of cumene was 98.95%.

[0087] Comparative Example 1

[0088] The catalyst used in Comparative Example 1 was reduced and activated at 600 °C and 4 MPaG under a hydrogen atmosphere for 6 h. Subsequently, the temperature of the reaction system was adjusted to 150 °C and the pressure to 1.8 MPaG, and dimethylbenzyl alcohol feedstock was introduced to a space velocity of 3 h⁻¹. -1 The hydrogenohydrin was subjected to a hydrogenolysis reaction at a volume ratio of 10. Analysis of the products after the reaction showed that the conversion rate of dimethylbenzyl alcohol was 48.75% and the selectivity of cumene was 37.28%.

[0089] Comparative Example 2

[0090] The catalyst used in Comparative Example 2 was reduced and activated at 600 °C and 4 MPaG under a hydrogen atmosphere for 6 h. Subsequently, the temperature of the reaction system was adjusted to 150 °C and the pressure to 1.8 MPaG, and dimethylbenzyl alcohol feedstock was introduced to a space velocity of 3 h⁻¹. -1 The hydrogenohydrin was subjected to a hydrogenolysis reaction at a volume ratio of 10. Analysis of the products after the reaction showed that the conversion rate of dimethylbenzyl alcohol was 45.38% and the selectivity of cumene was 39.42%.

Claims

1. A Co-based catalyst, characterized in that, It includes the active component Co, the doped metal M and the metal Nb, wherein the metal M is selected from one or more of Ti, Cu, Ni, W, etc.; Preferably, the molar ratio of Co, Nb and metal M is 2:0.25-0.6:0.3-0.8; more preferably 2:0.35-0.55:0.5-0.

7.

2. The method for preparing the catalyst according to claim 1, characterized in that, Solid powder compounds containing Co, Nb, and metal M are mixed, a dispersant is added and stirred into a paste, and then dried and calcined to prepare the final product.

3. The method for preparing the catalyst according to claim 2, characterized in that, The Co-containing compound is selected from one or more of cobalt oxide, cobalt nitrate, and cobalt oxalate; Nb-containing compounds are derived from one or more of niobate oxalate and niobic acid; The Ti-containing compounds are derived from one or more of metatitanic acid and titanium oxide; The Cu-containing compounds are derived from one or more of copper nitrate and basic copper carbonate; The Ni-containing compounds are derived from one or more of nickel nitrate, basic nickel carbonate, and nickel acetate; The W-containing compounds are derived from one or more of tungsten oxide and ammonium metatungstate; Preferably, the dispersant is any one or more of DMF, methanol, and acetonitrile; Preferably, the amount of the dispersant added is 0.3-0.6 times the total mass of the metal compound converted into oxides, more preferably 0.4-0.5 times.

4. The method for preparing the catalyst according to claim 2 or 3, characterized in that, The stirring process is carried out at a temperature of 20-45℃ for 2-4 hours. Preferably, the paste is first ground and then dried, with the grinding time controlled at 3-6 hours.

5. The method for preparing the catalyst according to any one of claims 2-4, characterized in that, The drying temperature is controlled at 10-30℃ below the boiling point of the selected dispersant, and the drying time is controlled at 1-3 hours. Preferably, the roasting process temperature is controlled at 300-700℃; the roasting process time is controlled at 3-8h.

6. A method for preparing cumene by hydrogenolysis of dimethylbenzyl alcohol, comprising reducing and activating the catalyst according to claim 1 or the catalyst prepared by any one of claims 2-5 under a hydrogen atmosphere, and then introducing dimethylbenzyl alcohol raw material under a hydrogen atmosphere to undergo a hydrogenolysis reaction to obtain cumene.

7. The method according to claim 6, characterized in that, The reduction and activation temperature under a hydrogen atmosphere is 600-900℃, the activation pressure is 3-5MPaG, and the activation time is 3-9h.

8. The method according to claim 6 or 7, characterized in that, The hydrogenolysis reaction temperature is 130-180℃, and the reaction pressure is 1.6-2.0 MPaG.

9. The method according to any one of claims 6-8, characterized in that, Liquid hourly space velocity is 1-4 h -1 .

10. The method according to any one of claims 6-9, characterized in that, The volume ratio of hydrogen alcohol is 8-12.