Catalyst for preparing styrene through alpha-phenethyl alcohol dehydration and preparation and application thereof

Abstract

The invention discloses a catalyst for preparing styrene through alpha-phenethyl alcohol dehydration and a preparation method and application thereof, the catalyst comprises a carrier, a main metal active component and an auxiliary metal active component, the carrier is a molecular sieve, the main metal active component is zirconium element, and the auxiliary metal active component is any one or more selected from potassium, sodium and calcium elements. The catalyst is simple in preparation process and easy to operate, in the presence of the catalyst, alpha-phenethyl alcohol is dehydrated to obtain styrene, the conversion rate of alpha-phenethyl alcohol and the selectivity of styrene are effectively improved, generated carbon deposition is less, and the catalyst is high in stability.

Description

Technical Field

[0001] The invention relates to a catalyst for preparing styrene by dehydrating alpha-phenylethanol, a preparation method and an application thereof, and belongs to the technical field of catalyst synthesis. Background Art

[0002] Styrene is an important organic chemical raw material that can be used to produce styrene-butadiene rubber, polystyrene, engineering plastics, etc. It can also be used in the pharmaceutical, pesticide, coating and other industries and has a wide range of uses.

[0003] At present, the production technology of styrene mainly includes three process routes: ethylbenzene dehydrogenation, propylene oxide / styrene co-production and styrene extraction from cracked gasoline. Among them, propylene oxide / styrene co-production produces styrene by catalytic α-phenylethanol dehydration reaction. α-phenylethanol dehydration reaction mainly includes two methods: liquid phase dehydration and gas phase dehydration.

[0004] The α-phenylethanol liquid phase dehydration method usually uses a homogeneous catalyst, and common catalysts include sulfuric acid, p-toluenesulfonic acid, etc. However, during the liquid phase dehydration process of α-phenylethanol, these catalysts will trigger side reactions, produce a series of by-products such as heavy components, increase the unit consumption of α-phenylethanol, and reduce the utilization rate of raw materials. US3639928 uses nitrophenol or replaces the sulfonic acid group with a nitro group to inhibit side reactions, but this method cannot fundamentally avoid the occurrence of side reactions, and still generates certain heavy components; and the use of a homogeneous catalyst for the dehydration reaction has high requirements on the material of the equipment, and there will be a certain amount of catalyst in the product after the reaction, resulting in the need to use an alkali washing method to remove the catalyst and a water washing method to remove the sodium ions before the subsequent separation and purification of the product. While using a large amount of alkali solution, a large amount of wastewater that is difficult to treat is also generated, increasing the production cost.

[0005] Solid acid catalysts are often used in the gas phase dehydration reaction of α-phenylethanol. CN108057432A discloses an alumina catalyst for the dehydration reaction of α-phenylethanol. The patent adds a pore expander to pseudo-boehmite, extrude strips by adding auxiliary agents after drying, obtains a shaped γ-alumina by drying and high temperature roasting, and then impregnates an alkali metal or alkaline earth metal on the surface of alumina, and obtains a catalyst after drying and high temperature roasting. Since the alumina labeling acidity is strong and styrene is easily polymerized under acidic action, although the conversion rate of α-phenylethanol and the selectivity of styrene in the gas phase dehydration method are high, carbon deposits are easily formed on the catalyst surface during the reaction, so that the catalyst activity gradually decreases, and frequent regeneration is required. Therefore, it is necessary to regulate the acid strength of the solid acid catalyst so that the catalyst has higher activity and stability, reduce production costs, and meet actual use requirements. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a catalyst for dehydrating α-phenylethanol to prepare styrene, a preparation method thereof and an application thereof. The catalyst of the present invention has high catalytic activity, selectivity and stability.

[0007] The present invention adopts the following technical solution:

[0008] A catalyst for preparing styrene by dehydrating α-phenylethanol comprises a carrier, a main metal active component and a secondary metal active component, wherein the carrier is a molecular sieve, the main metal active component is zirconium, and the secondary metal active component is selected from any one or more of potassium, sodium and calcium. Based on the total mass of the catalyst, the loading amount of the main metal active component is 0.1% to 2.5wt%, and the loading amount of the secondary metal active component is 0.01 to 1wt%.

[0009] Preferably, based on the total mass of the catalyst, the loading amount of the main metal active component is 0.2% to 2.0 wt%, and the loading amount of the secondary metal active component is 0.05 to 1 wt%.

[0010] Preferably, the carrier is a dealuminated molecular sieve.

[0011] The present invention also provides a method for preparing the α-phenylethanol dehydration catalyst, comprising the following steps:

[0012] Step 1: Mix the molecular sieve and the zirconium salt solution, stir, dry and calcine to obtain the zirconium modified molecular sieve.

[0013] Step 2: Mix the zirconium-modified molecular sieve obtained in step 1 with the salt solution of the auxiliary metal active component, stir, and dry to obtain a catalyst.

[0014] Preferably, the molecular sieve is a dealuminated molecular sieve; the method for preparing the dealuminated molecular sieve is: mixing beta molecular sieve with acid, reacting, and then washing and drying to obtain the dealuminated molecular sieve.

[0015] Preferably, the acid is selected from one or more of nitric acid, sulfuric acid, and hydrochloric acid, preferably 10-14M concentrated nitric acid or 9-11M concentrated hydrochloric acid, and 10-50 ml of acid solution, preferably 15-30 ml, is added per gram of molecular sieve.

[0016] Preferably, the beta molecular sieve reacts with the acid under heating conditions, the heating temperature is 70-100° C., preferably 80-95° C.; the heating time is 10-14 h, preferably 11-13 h.

[0017] In the present invention, the zirconium source is preferably zirconium oxychloride octahydrate.

[0018] In the present invention, the calcination temperature in step 1 is 500-600° C., preferably 550° C., and the calcination time is 7-15 hours, preferably 10 hours.

[0019] In the present invention, the salt of the secondary metal is selected from one or a mixture of potassium chloride, sodium chloride, potassium nitrate, sodium nitrate and calcium chloride.

[0020] In the present invention, the beta molecular sieve has a silicon-aluminum ratio of 10 to 100, and a beta molecular sieve with a silicon-aluminum ratio of 15 is preferred.

[0021] The invention also provides application of the catalyst in the reaction of preparing styrene by dehydrating alpha-phenylethanol.

[0022] A method for preparing styrene by dehydrating alpha-phenylethanol. Phenylethanol and water are firstly gasified, and then catalytically reacted in the presence of the catalyst of the invention to obtain styrene and water.

[0023] After the reaction, the gas phase is condensed and the crude styrene is obtained after phase separation.

[0024] In some preferred embodiments of the present invention, the reaction is carried out using a fixed bed reactor.

[0025] A certain mass of catalyst is weighed and loaded into a fixed bed reactor. At the reaction temperature, a-phenylethanol and water vapor are added into a vaporization chamber and mixed. The mixture is then heated by a preheater and then enters a fixed bed reactor. After the reaction, the gas is condensed to obtain water and styrene. The water phase is separated to obtain a styrene product.

[0026] The α-phenylethanol raw material in the present invention can be a high-purity (98% or more) α-phenylethanol raw material, or it can be an intermediate product in the propylene oxide / styrene joint production process after impurities are removed (α-phenylethanol purity is not less than 95%).

[0027] The mass ratio of the alpha-phenylethanol raw material to water in the present invention is 1:0.1-1.

[0028] In the present invention, the mass space velocity of α-phenylethanol relative to the catalyst is 0.1-5h -1 .

[0029] The reaction temperature described in the present invention is 200-350° C., and the reaction pressure is 10-150 kPa.

[0030] The condensation temperature of the gas after the reaction described in the present invention is 10-50° C., and the condensation method adopts a rapid cooling method.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The prepared catalyst has high activity and a wide reaction temperature range, and the conversion rate of α-phenylethanol at 200-350° C. is higher than 97%;

[0033] (2) The zirconium element is anchored by the hydroxyl nest, which can effectively prevent the agglomeration of zirconium on the surface of the molecular sieve and promote the uniform distribution of zirconium on the surface of the molecular sieve. The prepared catalyst has good stability and the conversion rate of α-phenylethanol does not decrease significantly after continuous operation for 500 hours.

[0034] (3) Dealumination modification and the use of alkali metals to neutralize the strong acid sites on the surface of the molecular sieve reduce the occurrence of side reactions such as styrene polymerization, greatly reduce the types of by-products, and the styrene selectivity can reach more than 99%. DETAILED DESCRIPTION

[0035] Gas phase analysis conditions: Agilent chromatography online determination, using Agilent HP-5ms chromatographic column, vaporization chamber temperature of 300°C, detector temperature of 300°C, program temperature rise of 50°C for 2 min; 100°C for 1 min; 100°C to 300°C for 10 min.

[0036] The present invention is further described below in conjunction with examples, but the present invention is not limited to the following examples.

[0037] Embodiment 1:

[0038] Weigh 5g of beta molecular sieve with a silicon-aluminum ratio of 10, add 100ml of 14M concentrated nitric acid, stir at 90℃ for 10h; wash with pure water several times until the powder is neutral, and dry at 100℃ for 12h. Mix 4g of dealuminated beta molecular sieve with a solution containing 0.11g of zirconium oxychloride octahydrate, stir magnetically at room temperature for 12h, dry at 70℃, and calcine the obtained solid powder at 550℃ for 8h to obtain zirconium-doped beta molecular sieve. Mix zirconium-doped beta molecular sieve with 0.5ml of 0.15g / ml potassium nitrate aqueous solution, let stand at room temperature for 12h, and dry at 70℃ to finally obtain K-Zr / beta molecular sieve catalyst.

[0039] The prepared catalyst was placed in a metal reaction tube with an inner diameter of 14 mm. The vaporization chamber was heated to 250°C at a heating rate of 2°C / min, and the reaction tube was heated to 300°C. α-phenylethanol and water were introduced into the vaporization chamber at a mass ratio of 1:0.1 for gasification, and then heated to 290°C by a preheater. The mass space velocity of the mixed gas entering the reactor was adjusted to 1h -1 After being heated by the preheater, it enters the reaction zone with a reaction pressure of 100KPa. After dehydration, the material enters the condenser, and after being rapidly cooled to 50°C, it enters the oil-water separator to separate the wastewater and obtain the crude styrene product. After testing, the initial conversion rate of α-phenylethanol is 97.3%, the initial selectivity of styrene is 99.2%, and the deactivation rate Kd=0.012h -1 .

[0040] Embodiment 2:

[0041] Weigh 5g of beta molecular sieve with a silicon-aluminum ratio of 50, add 100ml of 12M concentrated nitric acid, stir at 95℃ for 12h; wash with pure water several times until the powder is neutral, and dry at 100℃ for 12h. Mix 4g of dealuminated beta molecular sieve with a solution containing 0.22g of zirconium oxychloride octahydrate, stir magnetically at room temperature for 12h, dry at 70℃, and calcine the obtained solid powder at 550℃ for 8h to obtain zirconium-doped beta molecular sieve. Mix the zirconium-doped beta molecular sieve with 0.5ml of 0.2g / ml sodium nitrate aqueous solution, let stand at room temperature for 12h, and dry at 70℃ to finally obtain Na-Zr / beta molecular sieve catalyst.

[0042] The prepared catalyst was placed in a metal reaction tube with an inner diameter of 14 mm. The vaporization chamber was heated to 250°C at a heating rate of 2°C / min, and the reaction tube was heated to 300°C. α-phenylethanol and water were introduced into the vaporization chamber at a mass ratio of 1:0.1 for gasification, and then heated to 290°C by a preheater. The mass space velocity of the mixed gas entering the reactor was adjusted to 3h / min. -1 After being heated by the preheater, it enters the reaction zone with a reaction pressure of 100KPa. After dehydration, the material enters the condenser, and after being rapidly cooled to 50°C, it enters the oil-water separator to separate the wastewater and obtain the crude styrene product. After testing, the initial conversion rate of α-phenylethanol is 96.1%, the initial selectivity of styrene is 99.3%, and the deactivation rate Kd=0.015h -1 .

[0043] Embodiment 3:

[0044] Weigh 5g of beta molecular sieve with a silicon-aluminum ratio of 90, add 150ml of 11M concentrated hydrochloric acid, stir at 90℃ for 12h; wash with pure water several times until the powder is neutral, and dry at 100℃ for 12h. Mix 4g of dealuminated beta molecular sieve with a solution containing 0.33g of zirconium oxychloride octahydrate, stir magnetically at room temperature for 12h, dry at 70℃, and calcine the obtained solid powder at 550℃ for 8h to obtain zirconium-doped beta molecular sieve. Mix zirconium-doped beta molecular sieve with 1ml of 0.08g / ml calcium chloride aqueous solution, let stand at room temperature for 12h, and dry at 70℃ to finally obtain Ca-Zr / beta molecular sieve catalyst.

[0045] The prepared catalyst was placed in a metal reaction tube with an inner diameter of 14 mm. The vaporization chamber was heated to 250°C at a heating rate of 2°C / min, and the reaction tube was heated to 300°C. α-phenylethanol and water were introduced into the vaporization chamber at a mass ratio of 1:0.1 for gasification, and then heated to 290°C by a preheater. The mass space velocity of the mixed gas entering the reactor was adjusted to 3h / min. -1After being heated by the preheater, it enters the reaction zone with a reaction pressure of 100KPa. After dehydration, the material enters the condenser, is rapidly cooled to 50°C, and then enters the oil-water separator to separate the wastewater and obtain the crude styrene product. After testing, the initial conversion rate of α-phenylethanol is 94.4%, the initial selectivity of styrene is 97.6%, and the deactivation rate Kd=0.020h -1 .

[0046] Embodiment 4:

[0047] Weigh 5g of beta molecular sieve with a silicon-aluminum ratio of 200, add 100ml of 14M concentrated nitric acid, stir at 90℃ for 10h; wash with pure water several times until the powder is neutral, and dry at 100℃ for 12h. Mix 4g of dealuminated beta molecular sieve with a solution containing 0.11g of zirconium oxychloride octahydrate, stir magnetically at room temperature for 12h, dry at 70℃, and calcine the obtained solid powder at 550℃ for 8h to obtain zirconium-doped beta molecular sieve. Mix the zirconium-doped beta molecular sieve with 1ml of 0.08g / ml potassium chloride aqueous solution, let stand at room temperature for 12h, and dry at 70℃ to finally obtain K-Zr / beta molecular sieve catalyst.

[0048] The prepared catalyst was placed in a metal reaction tube with an inner diameter of 14 mm. The vaporization chamber was heated to 250°C at a heating rate of 2°C / min, and the reaction tube was heated to 300°C. α-phenylethanol and water were introduced into the vaporization chamber at a mass ratio of 1:0.2 for gasification, and then heated to 290°C by a preheater. The mass space velocity of the mixed gas entering the reactor was adjusted to 1h -1 After being heated by the preheater, it enters the reaction zone with a reaction pressure of 50KPa. After dehydration, the material enters the condenser, is rapidly cooled to 50°C, and then enters the oil-water separator to separate the wastewater and obtain the crude styrene product. After testing, the initial conversion rate of α-phenylethanol is 98.6%, the initial selectivity of styrene is 99.3%, and the deactivation rate Kd=0.011h -1 .

[0049] Embodiment 5:

[0050] Weigh 5g of beta molecular sieve with a silicon-aluminum ratio of 15, add 150ml of 9M concentrated nitric acid, stir at 90℃ for 10h; wash with pure water several times until the powder is neutral, and dry at 100℃ for 12h. Mix 4g of dealuminated beta molecular sieve with a solution containing 0.22g of zirconium oxychloride octahydrate, stir magnetically at room temperature for 12h, dry at 70℃, and calcine the obtained solid powder at 550℃ for 8h to obtain zirconium-doped beta molecular sieve. Mix zirconium-doped beta molecular sieve with 0.5ml of 0.15g / ml potassium nitrate aqueous solution, let stand at room temperature for 12h, and dry at 70℃ to finally obtain K-Zr / beta molecular sieve catalyst.

[0051] The prepared catalyst was placed in a metal reaction tube with an inner diameter of 14 mm. The vaporization chamber was heated to 250°C at a heating rate of 2°C / min, and the reaction tube was heated to 300°C. α-phenylethanol and water were introduced into the vaporization chamber at a mass ratio of 1:0.2 for gasification, and then heated to 290°C by a preheater. The mass space velocity of the mixed gas entering the reactor was adjusted to 1h -1 After being heated by the preheater, it enters the reaction zone with a reaction pressure of 50KPa. After dehydration, the material enters the condenser, and after being rapidly cooled to 50°C, it enters the oil-water separator to separate the wastewater and obtain the crude styrene product. After testing, the initial conversion rate of α-phenylethanol is 96.5%, the initial selectivity of styrene is 99.6%, and the deactivation rate Kd=0.009h -1 .

[0052] Example 6

[0053] Weigh 4g of beta molecular sieve with a silicon-aluminum ratio of 10, mix it with a solution containing 0.22g of zirconium oxychloride octahydrate, stir it magnetically at room temperature for 12h, dry it at 70℃, and calcine the obtained solid powder at 550℃ for 8h to obtain zirconium-doped beta molecular sieve. Mix the zirconium-doped beta molecular sieve with 0.5ml of 0.15g / ml potassium nitrate aqueous solution, stir it magnetically at room temperature for 12h, and dry it at 70℃ to finally obtain K-Zr / beta molecular sieve catalyst.

[0054] The prepared catalyst was placed in a metal reaction tube with an inner diameter of 14 mm, and the vaporization chamber was heated to 250°C at a heating rate of 2°C / min, and the reaction tube was heated to 300°C. α-phenylethanol and water were introduced into the vaporization chamber at a mass ratio of 1:0.1 for gasification, and then heated to 290°C through a preheater. The mass space velocity of the mixed gas entering the reactor was adjusted to 1h -1 After being heated by the preheater, it enters the reaction zone with a reaction pressure of 50KPa. After dehydration, the material enters the condenser, is rapidly cooled to 50°C, and then enters the oil-water separator to separate the wastewater and obtain the crude styrene product. After testing, the initial conversion rate of α-phenylethanol is 93.1%, the initial selectivity of styrene is 88.2%, and the deactivation rate Kd=0.05h -1 .

[0055] Comparative Example 1:

[0056] Weigh 5g of beta molecular sieve with a silicon-aluminum ratio of 10, add 100ml of 14M concentrated nitric acid, stir at 90℃ for 10h; wash with pure water several times until the powder is neutral, and dry at 100℃ for 12h. Mix 4g of dealuminated beta molecular sieve with a solution containing 0.11g of zirconium oxychloride octahydrate, stir magnetically at room temperature for 12h, dry at 70℃, and calcine the obtained solid powder at 550℃ for 8h to obtain a zirconium-doped beta molecular sieve catalyst.

[0057] The prepared catalyst was placed in a metal reaction tube with an inner diameter of 14 mm. The vaporization chamber was heated to 250°C at a heating rate of 2°C / min, and the reaction tube was heated to 300°C. α-phenylethanol and water were introduced into the vaporization chamber at a mass ratio of 1:0.1 for gasification, and then heated to 290°C by a preheater. The mass space velocity of the mixed gas entering the reactor was adjusted to 1h -1 After being heated by the preheater, it enters the reaction zone with a reaction pressure of 100KPa. After dehydration, the material enters the condenser, is rapidly cooled to 50°C, and then enters the oil-water separator to separate the wastewater and obtain the crude styrene product. After testing, the initial conversion rate of α-phenylethanol is 90.1%, the initial selectivity of styrene is 96.1%, and the deactivation rate Kd=0.104h -1 .

Claims

1. A catalyst for dehydrating α-phenylethanol to prepare styrene, characterized in that: It comprises a carrier, a main metal active component and a secondary metal active component, wherein the carrier is a molecular sieve, the main metal active component is zirconium, and the secondary metal active component is selected from any one or more of potassium, sodium and calcium; Preferably, the molecular sieve is a dealuminated molecular sieve.

2. The catalyst according to claim 1, characterized in that Based on the total mass of the catalyst, the loading amount of the main metal active component is 0.1% to 2.5wt%, and the loading amount of the secondary metal active component is 0.01 to 1wt%; Preferably, based on the total mass of the catalyst, the loading amount of the main metal active component is 0.2% to 2.0 wt%, and the loading amount of the secondary metal active component is 0.05 to 1 wt%.

3. The method for preparing the catalyst according to claim 1, characterized in that: The steps include: Step 1, mixing the molecular sieve and the zirconium salt solution, stirring, drying, and calcining to obtain the zirconium modified molecular sieve; Step 2: Mix the zirconium-modified molecular sieve obtained in step 1 with the salt solution of the auxiliary metal active component, stir, and dry to obtain a catalyst.

4. The method for preparing the catalyst according to claim 3, characterized in that: The molecular sieve is a dealuminated molecular sieve; Preferably, the method for preparing the dealuminated molecular sieve is: mixing beta molecular sieve with acid, reacting, and then washing and drying to obtain the dealuminated molecular sieve; Preferably, the beta molecular sieve has a silicon-aluminum ratio of 10 to 100, preferably a beta molecular sieve with a silicon-aluminum ratio of 15; Preferably, the acid is selected from one or more of nitric acid, sulfuric acid, and hydrochloric acid, preferably 10-14M concentrated nitric acid or 9-11M concentrated hydrochloric acid; Preferably, 10-50 ml of acid solution, preferably 15-30 ml, is added per gram of molecular sieve.

5. The method for preparing the catalyst according to claim 3 or 4, characterized in that: The beta molecular sieve reacts with the acid under heating conditions, the heating temperature is 70-100°C, preferably 80-95°C; the heating time is 10-14h, preferably 11-13h; Preferably, the calcination temperature in step 1 is 500-600°C, preferably 550°C, and the calcination time is 7-15h, preferably 10h; Preferably, the salt of the secondary metal is selected from one or a mixture of potassium chloride, sodium chloride, potassium nitrate, sodium nitrate and calcium chloride.

6. Use of the catalyst according to claim 1 or 2 or the catalyst prepared by the preparation method according to any one of claims 3 to 5 in the reaction of dehydrating α-phenylethanol to prepare styrene.

7. A method for preparing styrene by dehydrating α-phenylethanol, wherein phenylethanol and water are firstly gasified and then catalytically reacted in the presence of the catalyst according to claim 1 or 2 or the catalyst prepared by the preparation method according to any one of claims 3 to 5 to obtain styrene and water.

8. The preparation method according to claim 7, characterized in that: The reaction adopts a fixed bed reactor; Preferably, a certain mass of catalyst is weighed and loaded into a fixed bed reactor. At the reaction temperature, a-phenylethanol and water vapor are added into a vaporization chamber and mixed, and then heated by a preheater and enter the fixed bed reactor. After the reaction, the gas is condensed to obtain water and styrene, and the water phase is separated to obtain a styrene product.

9. The preparation method according to claim 7, characterized in that: The mass ratio of the α-phenylethanol raw material to water is 1:0.1-1; Preferably, the mass space velocity of α-phenylethanol to the catalyst is 0.1-5h -1 ; Preferably, the reaction temperature is 200-350°C, and the reaction pressure is 10-150 kPa; Preferably, the condensation temperature of the gas after the reaction is 10-50° C., and the condensation method is a rapid cooling method.