CN1923364A - Catalyst for producing styrene by dehydrogenation of ethylbenzene and preparation method thereof - Google Patents

Abstract

The invention provides a catalyst for preparing styrene by ethylbenzene dehydrogenation and a preparation method thereof. The catalyst comprises the following active components in parts by mass: 63-85 parts of iron oxide, 6-15 parts of potassium oxide, 4-10 parts of cerium oxide, 1-5 parts of molybdenum oxide, 1-6 parts of magnesium oxide, 0.1-3 parts of copper oxide, 0.1-0.8 part of lanthanum oxide, 1-9 parts of reinforcing agent and 3.5-5 m of specific surface area²The lateral pressure strength is more than or equal to 25N/mm. The catalyst for preparing styrene by ethylbenzene dehydrogenation has the reaction temperature of 600 ℃ and the liquid airspeed of 0.6h^－1And under the condition of isothermal normal pressure evaluation with the water-oil ratio of 1.3, the conversion rate is more than or equal to 70 percent, and the selectivity is more than or equal to 94.5 percent. Under certain technological conditions, the catalyst may be also used in dehydrogenating diethylbenzene and methyl ethyl benzene to prepare divinylbenzene and methyl styrene.

Description

Catalyst for producing styrene by dehydrogenation of ethylbenzene and preparation method thereof

technical field

The invention relates to a catalyst for preparing styrene by dehydrogenation of ethylbenzene and a preparation method thereof, in particular to a catalyst with high activity, high strength and large specific surface area suitable for a water-to-oil ratio (H ₂ O/ethylbenzene mass ratio) of 1.3 catalyst. The catalyst can also be used for the dehydrogenation of diethylbenzene to produce divinylbenzene or the dehydrogenation of methylethylbenzene to produce methylstyrene.

Background technique

At present, the industrially used catalysts for the dehydrogenation of ethylbenzene to styrene are all iron-based catalysts. That is to say, iron oxide is used as the main active component, and additives such as alkali metal or alkaline earth metal, rare earth element are added, and it is made by dry blending, extruding and activating. The basic composition of ethylbenzene dehydrogenation styrene catalyst is developed from Fe-K-Cr, Fe-K-Ce-Mo to Fe-K-Ce-Mo-Mg, the purpose is to continuously improve the activity, selectivity and stability of the catalyst sex. With the emergence of the world's energy crisis, research in this field not only emphasizes activity and selectivity, but also tends to "energy-saving" research, that is, to reduce the water ratio of catalysts to improve production capacity and save a lot of energy. In the production process of ethylbenzene dehydrogenation to styrene, adding water vapor has three main functions: ①Reduce the partial pressure of styrene, which is beneficial to the reaction balance; ②Remove the carbon on the surface of the catalyst to prevent coking; ③Provide heat source and prevent Ethylbenzene overheats locally. However, in order to save energy, try to reduce the ratio of water used on the premise of ensuring the activity and life of the catalyst. In recent years, continuously reducing the ratio of water used is one of the main development directions of the catalyst.

Patent Publication No. 59-216634, Japanese Patent Application No. 61-90741, European Patent No. 0177832 and other patents all add magnesium and calcium to the iron-potassium-cerium-molybdenum system to reduce the water ratio. U.S. patents 3360579, 3361683, 3387053, 3409688, 3703593, 4134858, 4152300, British patent 1405796, WO8300687, Canadian patent 1046481, etc. all use iron-potassium-chromium as the main composition, and then add other elements to reduce the use of water ratio . But the selectivity is generally low, no more than 94%. Chinese patent CN1226462A proposes a catalyst developed with iron-potassium-cerium as an effective component without molybdenum, tungsten, vanadium, magnesium, tin and other additives, which is suitable for operation at a low water ratio of 1.4; CN1470325A is based on iron-potassium-cerium Cerium-molybdenum-magnesium is the main component, and the catalyst is made by adding various metal oxides, porogens and binders. It can be used at a water ratio of 2.0, and has high conversion rate and selectivity. CN1050535C provides with iron-potassium-molybdenum-magnesium-rare earth metal as main component, adds the catalyst of multiple metal oxides, and it has excellent conversion rate, selectivity, but does not point out the space velocity condition of evaluation (this processing condition is an important factor in evaluating catalyst performance).

Contents of the invention

The object of the present invention is to provide a catalyst for preparing styrene from ethylbenzene dehydrogenation suitable for use under the condition of low water ratio (water/ethylbenzene≤1.3) and a preparation method thereof.

The object of the present invention is implemented by the following technical solutions (taking the catalyst as 100 parts by mass, the same below):

A catalyst for preparing styrene from ethylbenzene dehydrogenation, its active composition is in parts by mass, containing

a) 63-85 parts of iron oxide, calculated as Fe ₂ O ₃

b) 6-15 parts of potassium oxide, calculated as K ₂ O

c) 4-10 parts of cerium oxide, calculated as Ce ₂ O ₃

d) 1 to 5 parts of molybdenum oxide, calculated as _MoO3

e) 1-6 parts of magnesium oxide, calculated as MgO

f) 0.1-3 parts of copper oxide, calculated as CuO

g) 0.10-0.8 parts of lanthanum oxide, calculated as lanthanum oxide

The specific surface area is 3.5-5m ² /g, and the lateral compressive strength is ≥25N/mm.

The catalyst may also contain 1 to 9 parts of reinforcing agent.

The present invention also provides a kind of preparation method of this catalyst:

Add metal oxides or metal salts containing active components, and add reinforcing agents, such as cement, silica gel, etc.; then add 0.5 to 1 part of pore-forming agents, such as carbon black, carboxymethyl cellulose, methyl cellulose Su, tianjing powder, etc. Dry mix the above components for 0.5-4 hours, add deionized water and knead for 0.5-3 hours, extrude and cut into semi-finished catalysts of Φ3-3.3mm×5-8mm, dry at 80-120°C, 300- Activate and calcinate at 900°C for 8-12 hours to become the catalyst of the present invention.

The copper oxide used in the present invention, in terms of CuO, has an optimal range of 0.5 to 1 part. Experiments have proved that copper oxide is an essential component in the active component, and it plays a decisive role in the conversion rate of ethylbenzene, and its addition will inhibit the conversion rate of ethylbenzene. Activity, if the amount added is too small, it will basically have no effect on the activity. The lanthanum oxide used is also an essential component, which plays a decisive role in the stability. If the amount added is too large, the cost of the catalyst will increase, and if the amount added is too small, the stability will decrease. In terms of lanthanum oxide, the optimal range is 0.2 to 0.6 parts. It is best added in the form of nitrate. Iron is added in the form of oxides, preferably iron red and iron yellow oxides, preferably mixed in a ratio of (1.5-1.0):(1.0-1.5). Especially in the ratio of (1.2～1.0):(1～1.2) the mixing effect is better. Potassium, molybdenum, cerium, and magnesium are added in the form of oxides or salts. The catalyst provided by the invention uses iron-potassium-cerium-molybdenum-magnesium as the main system, and uses Cu-La combination as an auxiliary component, so as to be suitable for application under the condition of low water-oil ratio (water/ethylbenzene≤1.3). The catalyst of the present invention is the same as other styrene catalysts, and a certain amount of reinforcing agent needs to be added therein to improve the strength of the catalyst. The reinforcing agent can be general cement, silicic acid, etc., but when preparing the catalyst in the present invention, an appropriate amount of The pore agent improves the pore structure of the catalyst so that it has a suitable specific surface area, which is larger than that of catalysts usually used in high water-oil ratio conditions (2 ~ 3.2m ² /g), and the specific surface area of the catalyst of the present invention is 3.5 ～5m ² /g (preferably 3.8～5m ² /g), lateral compressive strength ≥ 25N/mm. The ethylbenzene dehydrogenation styrene catalyst of the present invention has a conversion rate of ≥70% and a selectivity of ≥94.5% under the isothermal and normal pressure evaluation conditions of a reaction temperature of 600°C, a liquid space velocity of 0.6h ^-1 , and a water-to-oil ratio of 1.3. Under the isothermal and normal pressure evaluation conditions of reaction temperature 600°C, liquid space velocity 0.7h ^-1 , water-oil ratio 1.5, the conversion rate can reach over 72%, and the selectivity can reach over 96%.

The catalyst for preparing styrene by dehydrogenating ethylbenzene of the present invention can also be used for preparing divinylbenzene and methylstyrene by dehydrogenating diethylbenzene and methylethylbenzene under certain process conditions.

The catalyst prepared according to the above technical scheme is evaluated for activity in an isothermal fixed bed, and the evaluation process is briefly described as follows:

According to the requirements of the process conditions, the ethylbenzene and water are respectively sent into the mixer by metering pumps, and enter the catalyst bed after being preheated and vaporized. The dehydrogenated product enters the cooler through the quencher, and the gas-liquid separation is carried out through the gas-liquid separator. The liquid phase product is then separated from oil and water by the oil-water separator, and the composition of the oil phase is analyzed by liquid chromatography. The reaction tube is a stainless steel tube, which can be filled with 100ml of catalyst.

Ethylbenzene conversion rate and styrene selectivity are calculated according to the following formula:

Specific surface area test method: according to GB/T-5816-86.

Lateral pressure strength test method: according to GB-3635-83.

Detailed ways

The present invention will be further elaborated below by Examples and Comparative Examples.

[Example 1] 153g iron oxide red, 170g iron oxide yellow, 100g potassium carbonate, 13g ammonium molybdate, 16g magnesium oxide, 32g cement, 4.5g copper oxide, 1.8g lanthanum oxide, 4g safflower powder are added in the kneader After 2 hours of dry mixing, 85g of cerium nitrate was dissolved in deionized water and added to it, and kneaded for 2 hours to knead the material into an extrudable paste, then take it out, and go through the extruding and breaking processes to make Φ3 A cylindrical catalyst of ~3.3mm×5~8mm was dried at 90°C for 4 hours, placed in a muffle furnace for activation and calcined at 750°C for 10 hours, and then cooled naturally to obtain the catalyst of the present invention.

The activity of the catalyst was evaluated.

Put 100ml of catalyst into the isothermal furnace tube, and evaluate its effect under the conditions of 600°C, water-to-oil ratio 1.3, and space velocity 0.6, as shown in Table 1.

[Example 2] Prepare catalyst by Example 1, difference is to add 160g iron oxide red, 160g iron oxide yellow, 105g potassium carbonate, 5.5g cupric oxide, 2.1g lanthanum oxide. The evaluation results are shown in Table 1.

[Example 3] Catalyst was prepared according to Example 1, except that 5g of copper oxide, 2.0g of lanthanum oxide, and 2.5g of carbon black were added without adding safflower powder. The evaluation results are shown in Table 1.

[Example 4] The catalyst was prepared according to Example 1, except that 8 g of copper oxide and 4 g of lanthanum oxide were activated at 550° C. for 8 hours. The evaluation results are shown in Table 1.

[Example 5] The catalyst was prepared according to Example 1, except that 170 g of iron oxide red, 150 g of iron oxide yellow, 10 g of copper oxide, and 2.5 g of lanthanum oxide were added. The evaluation results are shown in Table 1.

[Example 6] Using the composition formula shown in Table 2, after mixing and kneading, extrude into strip-shaped particles with a diameter of 3 mm and a length of 8-10 mm, and roast at 600 ° C for 6 hours. Using the same evaluation device as in Example 1, the evaluation results under different conditions are shown in Table 4.

[Comparative Example 1] The catalyst was prepared according to Example 1, except that only 8 g of copper oxide was added, and lanthanum oxide was not added. The evaluation results are shown in Table 1.

[Comparative Example 2] The catalyst was prepared according to Example 1, except that only 2 g of lanthanum oxide was added, and copper oxide was not added. The evaluation results are shown in Table 1.

[Comparative Example 3] The catalyst was prepared according to Example 1, except that copper oxide and lanthanum oxide were not added. The evaluation results are shown in Table 1.

[Comparative Example 4] The catalyst was prepared according to Example 1, except that 12 g of copper oxide and 2.5 g of lanthanum oxide were added. The evaluation results are shown in Table 1.

[Comparative Example 5] The catalyst was prepared according to Example 1, except that 3 g of copper oxide was added, and only 0.3 g of lanthanum oxide was added. The evaluation results are shown in Table 1.

[Comparative Example 6] Prepare the catalyst according to the conditions of Example 1 in CN1050535C, and the composition formula is as shown in Table 3. Using the same evaluation device as in Example 1, the evaluation results under different conditions are shown in Table 4.

The evaluation result of the catalyst obtained in table 1 embodiment and comparative example catalyst Ethylbenzene conversion % Styrene selectivity % Styrene concentration% Catalyst physical index Lateral compression strength N/mm Specific surface m ² /g Example 1 71.1 94.5 67.2 28 4.2 Example 2 70.4 94.6 66.0 25 4.8 Example 3 70.2 95.0 66.7 29 4.2 Example 4 70.0 94.5 66.2 28 4.8 Example 5 70.0 94.9 66.1 25 3.9 Comparative example 1 67.10 94.40 63.3 28 4.5 Comparative example 2 65.51 96.51 63.2 27 4.6 Comparative example 3 65.47 94.97 62.17 25 4.0 Comparative example 4 67.05 95.02 64.11 28 4.2 Comparative Example 5 Unstable, activity drops by 5% within 40 hours / / 26 4.8

The component ratio of table 2 embodiment 6 is: Component iron oxide potassium carbonate Cerium nitrate Molybdenum oxide Lanthanum oxide magnesium oxide Copper oxide cement carboxymethyl cellulose Dosage (grams) 330 80 93 15 2.0 16 4.5 36 4 Proportion of oxide % 66 10.8 7.0 3.0 0.40 3.2 0.9 7.2 0.8

The component ratio of Table 3 Comparative Example 6 is: Component iron oxide potassium carbonate Cerium oxalate Neodymium oxalate magnesium oxide Copper oxide cement carboxymethyl cellulose Dosage (grams) 279 54 50 10 9 0.9 35 4.1 Proportion of oxide % 63.12 8.3 10.09 2.02 2.0 0.2 7.9 0.93

Table 4 Example 6, the evaluation results of the catalyst obtained in Comparative Example 6 catalyst Evaluation conditions: 620°C, 2.0 water ratio Ethylbenzene conversion % Styrene selectivity % Styrene concentration% Example 6 80.14 94.72 75.90 Comparative example 6 77.15 95.35 73.56 Evaluation conditions: 600°C, 1.3 water ratio Example 6 70.40 94.6 66.0 Comparative example 6 65.20 93.45 60.92

Claims (11)

1. A catalyst for preparing styrene from ethylbenzene dehydrogenation, with catalyst mass parts as 100 parts, its active composition contains (1) 63-85 parts of iron oxide, calculated as Fe ₂ O ₃ (2) 6-15 parts of potassium oxide, calculated as K ₂ O (3) 4 to 10 parts of cerium oxide, calculated as Ce ₂ O ₃ (4) 1 to 5 parts of molybdenum oxide, calculated as _MoO3 (5) 1 to 6 parts of magnesium oxide, calculated as MgO (6) 0.1 to 3 parts of copper oxide, calculated as CuO (7) 0.10 to 0.8 parts of lanthanum oxide, calculated as lanthanum oxide The specific surface area is 3.5-5m ² /g, and the lateral compressive strength is ≥25N/mm. 2. The catalyst according to claim 1, characterized in that there are 1 to 9 parts of reinforcing agent in the catalyst. 3. The catalyst according to claim 1, characterized in that copper oxide, calculated as CuO, is added in an amount of 0.5 to 1 part. 4. The catalyst according to claim 1, characterized in that lanthanum oxide is calculated as lanthanum oxide, and its addition amount is 0.2 to 0.6 parts. 5. The catalyst according to claim 2, characterized in that the reinforcing agent is cement, silica gel. 6. The catalyst according to claim 1, characterized in that the specific surface area is 3.8-5 m ² /g. 7. A method for preparing a catalyst according to claim 1, characterized in that the metal oxide containing the active component or its metal salt is added, and a reinforcing agent is added, and then 0.5 to 1 part of pore-forming agent is added, and the above-mentioned The components are firstly mixed by dry method for 0.5-4 hours, then added with deionized water and kneaded for 0.5-3 hours, extruded and diced into a semi-finished catalyst of Φ3-3.3mm×5-8mm, dried at 80-120°C, 300-900°C The catalyst is obtained by activating and calcining for 8-12 hours. 8. The catalyst preparation method according to claim 7, characterized in that the pore-forming agent is carbon black, carboxymethyl cellulose, methyl cellulose, and turnip powder. 9. The catalyst preparation method according to claim 7, characterized in that iron is added in the form of oxides, two oxides of iron red and iron yellow are selected. 10. The catalyst preparation method according to claim 9, characterized in that the ratio of iron red to iron yellow is (1.5-1.0): (1.0-1.5). 11. The catalyst preparation method according to claim 9, characterized in that the ratio of iron red to iron yellow is (1.2-1.0): (1-1.2).