CN1226091C - Dehydrogenation catalysts for the preparation of alkenyl aromatics - Google Patents

Abstract

The present invention relates to a dehydrogenation catalyst for preparing alkyl thiazolinyl aromatic. The present invention mainly solves the problems that when the catalyst in the prior art is in use, the active components easily run off, the strength of the catalyst is poor and influenced; the present invention favorably solves the problems by adopting the technical scheme that barium components are added in a ferrum-potassium-cerium-molybdenum catalytic system. The present invention can be used for the industrial production of alkyl thiazolinyl aromatic.

Description

Dehydrogenation catalysts for the preparation of alkenyl aromatics

Technical field

The present invention relates to a dehydrogenation catalyst for the preparation of alkenyl aromatics, in particular to a catalyst for the preparation of styrene, divinylbenzene or alpha-methylstyrene.

Background technique

The industrial production of alkenyl aromatics is achieved by the dehydrogenation of alkyl aromatics. The basic composition of the catalyst used is a main catalyst, a co-catalyst, a porogen, a reinforcing agent, and the like. Catalysts reported in patents can be divided into two broad categories. One type is Fe-K series catalysts containing Cr, such as published US patents US4467046, US4684619 and European patent _EP0195252A2 . Although this type of catalyst has good activity and stability, due to the existence of more or less Cr oxides in the composition, the preparation, operation and waste catalyst treatment of the catalyst will cause certain environmental pollution and have been gradually eliminated. The other is the Fe-K-Ce-Mo series successfully developed in the early 1980s, such as published US patents US5190906, US4804799, world patent WO09839278A ₁ , etc. This kind of catalyst replaces Cr with Ce and Mo, so that the activity of the catalyst is greatly improved compared with the former on the basis of maintaining the original stability, and has been adopted by styrene manufacturers all over the world. Its main problems are that the main components of this type of catalyst will lose quickly during use, the catalyst has poor anti-fluctuation performance, and the catalyst strength is poor, which directly affects the service life of the catalyst.

Contents of Invention

The technical problem to be solved by the present invention is to overcome the problems in the prior literature that the active components are easy to lose during the use of the catalyst, the catalyst strength is poor, and the catalyst life is affected, and to provide a new dehydrogenation catalyst for the preparation of alkenyl aromatic hydrocarbons. The catalyst has the characteristics of high selectivity of alkenyl arene, high yield of alkenyl arene, good catalyst strength and good catalyst stability.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is as follows: a dehydrogenation catalyst for preparing alkenyl aromatic hydrocarbons, comprising the following active components in weight percent:

a) 55-85% _{Fe2O3 ;}

b) 4-20% _K2O ;

c) 4-12% _{Ce2O3 ;}

d) 0.3-4% _MoO3 ;

e) 0.1-4% BaO;

f) 0.001 to 5% of at least one oxide selected from Mg, Cu, Zn, Ti, Zr, W, Mn, Ni or V;

The Fe ₂ O ₃ is composed of Fe ₂ O ₃ and Fe ₂ O ₃ ·H ₂ O, and the weight ratio of Fe ₂ O ₃ : _{Fe 2} O ₃ ·H ₂ O is 0.2-5:1.

In the above technical solution, the preferred range of BaO is 0.1-2% by weight, more preferably 0.1-1.2%, and the preferred range of Fe ₂ O ₃ : Fe ₂ O ₃ ·H ₂ O by weight is 1.0 ~4:1. In terms of weight percentage, the active component also contains 0.01-5% CaO, preferably 1.5-4%. In terms of weight percentage, the amount of at least one oxide selected from Mg, Cu, Zn, Ti, Zr, W, Mn, Ni or V preferably ranges from 0.1 to 3.5%.

The used raw material of catalyst component among the present invention is as follows:

Potassium is added as potassium salt; cerium is added as oxide, hydroxide or cerium salt; molybdenum is added as its salt or oxide; barium is added as its sulfate, oxide or hydroxide, and calcium is added as its calcium oxide or Calcium hydroxide is added; elements selected from Mg, Cu, Zn, Ti, Zr, W, Mn, Ni or V are added in the form of their salts or oxides, and iron oxides are added in the form of iron oxide red and iron oxide yellow.

During the preparation of the catalyst of the present invention, a pore-forming agent may also be included in an amount of 1-4% of the weight of the catalyst, which may be selected from graphite, polystyrene microspheres, carboxymethyl cellulose and the like. In addition, there is a binder, generally cement, and its dosage is 0.1-10% of the weight of the catalyst.

Catalyst preparation method of the present invention:

Firstly, the required raw materials are pretreated, including crushing the selected coarse-grained oxides to make the particles reach 150 mesh. After uniformly mixing Fe, K, Ce, Mo, Ba and other co-catalyst components, binders, and pore-forming agents to be added according to the proportion, add an appropriate amount of deionized water to make a viscous, suitable for extrusion The lumps of strips are extruded and cut into particles with a diameter of 3 mm and a length of 5-8 mm, dried at 80-120 °C for 1-10 hours, and then roasted at 600-1000 °C for 1-8 hours. The finished catalyst can be obtained.

The dehydrogenation catalyst of the present invention can be completely suitable for producing styrene, divinylbenzene and alpha-methylstyrene from ethylbenzene, diethylbenzene and alpha-methylethylbenzene under certain process conditions.

The catalyst prepared by the above method is evaluated for activity in a small-scale adiabatic fixed-bed reactor. For the evaluation of the activity of ethylbenzene dehydrogenation to styrene, the brief process is as follows:

Ethylbenzene and water are respectively fed into the preheater through the metering pump and water is fed into the high temperature heater through the metering pump. The water vapor generated by the metering pump enters the first adiabatic reactor in a gaseous state after being mixed, and the gas phase material at the outlet of the first reactor is heated to a predetermined temperature. After the temperature, enter the second adiabatic reactor, the two reactors are stainless steel tubes with an internal diameter of 50 mm, which can be filled with 750 ml of catalysts with a particle size of 3.0 mm. The dehydrogenation products flowing out from the reactor were condensed with water and analyzed by gas chromatography.

Catalyst evaluation conditions in the adiabatic fixed bed reactor are as follows: reactor inlet temperature: first reactor 610°C, second reactor 615°C, reaction pressure 50KPa, liquid space velocity 0.5h Benzene (weight) is 1.3.

Ethylbenzene conversion and styrene selectivity are calculated by the following formula:

The present invention introduces barium element into the Fe-K-Ce-Mo catalyst system, so that the catalyst is more likely to form iron-potassium spinel structure, so that the catalyst can maintain a better conversion rate at a lower temperature. In addition, in this system A small amount of several metal oxides and their pore-forming agents are added to the catalyst to maintain a good activity and a high selectivity at the same time. Adding calcium oxide and a small amount of metal oxide to the catalyst is beneficial to improve the mechanical strength and water resistance of the catalyst. In the present invention, by adding other metal oxides in the Fe-K-Ce-Mo system, when the potassium content of the catalyst is about 9 to 10% (weight), the reactor inlet temperature I is 610°C/II is 615°C, When the reaction pressure is 50KPaA, the liquid space velocity is 0.5 hours-1, and the water/ethylbenzene ratio is 1.3 (weight), the styrene yield reaches 68%, the catalyst strength reaches 2.4 kg/mm, and the attrition rate is only 0.4%. , The catalyst has been tested under aging conditions, and the stability is good, and good technical effects have been achieved.

Below by embodiment the present invention will be further elaborated.

Detailed ways

【Example 1】

2130 grams of iron oxide red, 1329 grams of iron oxide yellow, 642 grams of potassium sulfate, 850 grams of cerium nitrate, 152 grams of ammonium molybdate, 85 grams of magnesium oxide, 75 grams of barium carbonate, 230 grams of cement, and 100 grams of carboxymethyl cellulose , 20 grams of copper oxide and 15 grams of manganese dioxide were mixed and stirred in a container for 1.5 hours, and an appropriate amount of water was added, and stirred for another 2 hours. Bake for 2 hours, bake at 120°C for 2 hours, then bake at a high temperature of 750°C for 4 hours, and after cooling, the catalyst is prepared. Catalyst evaluation conditions are as follows: 1500 milliliters, the catalyst of particle diameter 3 millimeters is divided into two parts (each 750 milliliters) and packed in laboratory adiabatic reactor, and reaction pressure is 50KPaA, and liquid space velocity is 0.5 hour ^-1 , the first reactor The inlet temperature was 610°C and the second reactor inlet temperature was 615°C. The crushing strength was measured using a DL-II particle strength tester. The results are shown in Table 1, Table 2 and Table 3.

[Embodiments 2-3]

Prepare catalyst according to each step of embodiment 1, only change the content of catalyst component, then evaluate with the same method of embodiment 1, its result is shown in table 1, table 2, table 3.

[Comparative Example 1]

Prepare catalyst according to each step of embodiment 1, component does not add barium sulfate, evaluates with embodiment 1 same method then, its result is shown in table 1, table 2, table 3.

Table 1 Specific feeding amount Feeding amount, grams raw material Example 1 Example 2 Example 3 Comparative example 1 _{Fe2O3 _} 2130 2130 2130 2130 Fe ₂ O ₃ ·H ₂ O 1329 1329 1329 1329 K ₂ CO ₃ 642 642 642 642 Ce(NO ₃ ) ₃ 6H ₂ O 850 850 850 850 (NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O 152 152 152 152 MgO 85 85 85 85 cement 230 230 230 230 carboxymethyl cellulose 100 100 100 100 CuO 20 20 20 20 _MnO2 15 15 15 15 BaCO ₃ 75 50 25

Table 2 Catalyst Composition composition Example 1 Example 2 Example 3 Comparative example 1 _{Fe2O3 _} 72.0 72.7 72.6 73.0 K ₂ CO ₃ 9.5 9.5 9.5 9.6 Ce ₂ O ₃ 6.9 6.9 6.9 6.9 MoO ₃ 2.6 2.6 2.6 2.6 MgO 1.8 1.8 1.8 1.8 CaO 3.0 3.0 3.0 3.0 CuO 0.4 0.4 0.4 0.4 _MnO2 0.3 0.3 0.3 0.3 BaO 1.2 0.8 0.4

Table 3 catalyst performance comparison catalyst Ethylbenzene conversion % Styrene selectivity % Styrene revenue % Strength kg/mm Example 1 64.5 96.8 62.4 2.4 Example 2 66.5 97.4 64.7 2.4 Example 3 65.5 97.0 63.5 2.4 Comparative example 1 63.5 96.5 61.3 2.0

It can be seen from the data of the examples that the catalyst of the present invention, in the Fe-K-Ce-Mo system, adds barium oxide and several metal oxide additives, plus pore-forming agents and binders, and the dehydrogenation catalyst produced The catalyst not only has high activity and high selectivity, but also has good crush resistance, and is a highly efficient catalyst for the dehydrogenation of alkylaromatic hydrocarbons.

Claims (7)

1, a kind of dehydrogenation catalyst for preparing alkyl alkenyl arene comprises following active constituent by weight percentage:

A) 55～85% Fe ₂O ₃

B) 4～20% K ₂O;

C) 4～12% Ce ₂O ₃

D) 0.3～4% MoO ₃

E) 0.01～4% BaO;

F) 0.001～5% at least a oxide compound that is selected from Mg, Cu, Zn, Ti, Zr, W, Mn, Ni or V;

Fe wherein ₂O ₃By Fe ₂O ₃And Fe ₂O ₃H ₂O forms, by weight Fe ₂O ₃: Fe ₂O ₃H ₂O is 0.2～5: 1.

2,, it is characterized in that the consumption of BaO is 0.1～2% by weight percentage according to the dehydrogenation catalyst of the described preparation alkyl alkenyl arene of claim 1.

3,, it is characterized in that the consumption of BaO is 0.1～1.2% by weight percentage according to the dehydrogenation catalyst of the described preparation alkyl alkenyl arene of claim 2.

4,, it is characterized in that Fe by weight according to the dehydrogenation catalyst of the described preparation alkyl alkenyl arene of claim 1 ₂O ₃: Fe ₂O ₃H ₂O is 1.0～4: 1.

5,, it is characterized in that active constituent also comprises 0.01～5% CaO by weight percentage according to the dehydrogenation catalyst of the described preparation alkyl alkenyl arene of claim 1.

6,, it is characterized in that the amount of active constituent CaO is 1.5～4.0% by weight percentage according to the dehydrogenation catalyst of the described preparation alkyl alkenyl arene of claim 5.

7, according to the dehydrogenation catalyst of the described preparation alkyl alkenyl arene of claim 1, the consumption that it is characterized in that the oxide compound of at least a by weight percentage Mg of being selected from, Cu, Zn, Ti, Zr, W, Mn, Ni or V is 0.1～3.5%.