JPS58210850A - Catalyst for hydrogenating dealkylation, its production and using method thereof - Google Patents

Abstract

PURPOSE:To develop a catalyst for catalytic hydrogenating dealkylation of alkyl arom. hydrocarbons which has high activity and a long life and is regeneratable, by depositing Ir and alkaline earth metals on an alumina carrier. CONSTITUTION:Noncrystalline gamma the alumina having properties of 50-300m<2>/g surface area and 0.2-0.8ml/g pore volume is used as a carrier, and an aq. soln. of chloride boride, iodide, nitrate, sulfate or other water-soluble salts of alkaline earth metals such as Mg, Ca, Sr, Ba or the like is impregnated in the carrier which is then burned for 5hrs at 500 deg.C. An aq. soln. of chloride, etc. of Ir is impregnated in the surface, whereafter the carrier is dried to disperse and deposit Ir on the alumina carrier. Hydrocarbon oils contg. alkyl arom. compds. are dealkylated in the presence of hydrogen at 5-30kg/cm<2>G pressure, 0.1-3.0vol./ vol. per hour space velocity of liquid, 2-20mol/mol hydrogen/raw material ratio and 400-500 deg.C by using such catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a catalyst used in a catalytic hydrodealkylation process for alkyl aromatic hydrocarbons, and a method for producing and using the same. Regarding this. More specifically, the present invention relates to a method for producing a novel catalyst used in a method for dealkylating an alkyl aromatic hydrocarbon oil or a hydrocarbon oil containing an alkyl aromatic group in the presence of hydrogen, and a method for using the same. The typical catalytic hydrodealkylation method in industry is a method that uses a chromia-alumina catalyst disclosed in U.S. Pat. No. 2,951,886 and is carried out at a reaction temperature of around 650°C. as Neftekimya Magazine 1975, Volume 15, No. 1, 95
Ru, Rh, Pd, Os on the page.

A method has been reported in which benzene is produced by the demethylation reaction of toluene at a relatively low temperature of 400 to 500"C using a catalyst in which a precious metal of group Ⅰ such as Ir or PL is supported on alumina. However, there is much room for improvement in these noble metal catalysts in terms of catalytic activity, lifespan, reaction options, etc., and many catalyst systems are being considered, such as combinations of two or more noble metals and the addition of other transition metals. .

In the catalytic hydrodealkylation reaction of alkyl aromatic hydrocarbons, the present invention supports iridium and one or more elements selected from the group consisting of magnesium, calcium, strontium, and barium on alumina. The present invention relates to a method for producing a highly active, highly selective, long-life, and recyclable catalyst. When only iridium having hydrodealkylation activity is supported on alumina without using the method of the present invention, a catalyst whose activity has decreased due to coke adhesion due to long-term operation will have a 500%
When the coke is burned off at a temperature above that, the iridium that was highly dispersed on the alumina carrier will cause agglomeration, and even if it is reduced again, the activity will be significantly reduced and it cannot be reused. However, the activity of the catalyst according to the method of the present invention does not change at all even if it is baked in an oxygen atmosphere at 500°C.The catalyst, which has been deactivated due to coke adhesion, recovers to its original activity through coke combustion. Therefore, the catalyst according to the method of the present invention is easy to form coke.
It has become possible to use alkyl aromatics as raw materials.

The iridium-supported alumina catalyst is characterized in that it mainly performs only the demethylation reaction, and the gas product is mostly methane, and when propylbenzene is used as a raw material, ethylbenzene, toluene, and benzene are successively produced. It will generate. That is, by selecting appropriate reaction conditions, C9,
It becomes possible to selectively produce xylenes useful as raw materials for synthetic fibers from CIO alkyl aromatics. Furthermore, since the iridium-supported alumina catalyst has low activity for hydrogenating and decomposing aromatic rings, the product yield is high and the amount of hydrogen consumed is low, so it is economically advantageous.

By supporting alkaline earth elements such as magnesium, calcium, strontium, and barium on the iridium-supported alumina catalyst, which has the characteristics described above, it has become possible to regenerate the catalyst while retaining the original characteristics of the iridium-supported alumina catalyst. Furthermore, the coexistence of these alkaline earth metals on the alumina carrier has the effect of neutralizing the acid sites of alumina and suppressing the formation of coke, thereby extending the catalyst life accordingly.

As described in detail in the Examples, the catalyst is prepared by first supporting and baking an alkaline earth metal on alumina, and then supporting iridium. The alumina support is amorphous type I alumina, with a surface area of 50 to 300 m27g, preferably 150 to 250 +n2/g, and a pore volume of 0.2 to 0.8ml/g, preferably 0.4 to 0.6ml/g.
A material having physical properties of g is suitable. It is desirable that the alkaline earth metal is water-soluble and easily decomposed on an alumina carrier to form an oxide. For example, for mag unsalted metals, magnesium chloride, magnesium bromide, magnesium iodide, magnesium ammonium chloride, and magnesium chloride are used as alkaline earth metals. Magnesium sodium, potassium magnesium chloride, magnesium acetate, magnesium oxalate, magnesium sulfate,
Magnesium nitrate, etc. Calcium salts include calcium chloride, calcium bromide, calcium iodide, calcium sulfate, calcium nitrate, calcium chromate, etc. Strontium salts include sulfur chloride), strontium, strontium bromide, sulfur nitride, Examples of barium salts include strontium nitrate, strontium acetate, strontium oxalate, etc., and barium chloride, barium bromide, barium iodide, barium nitrate, barium acetate, etc., respectively. Iridium salts are also preferably water-soluble and highly dispersed on the carrier, such as iridium chloride, iridium bromide, iridium chloride, and sodium iridium.
Examples include iridium, iridium sulfate, hex→non-ammine iridium, and the like. Although the above compounds are representative examples, any other compound can be used as long as it fits within the spirit of the present invention.

The method for producing and using the catalyst will be explained in detail with reference to Examples below.

Example surface area 180 m27g, pore volume 0.45 ml
/g of type I alumina i, o o g of distilled water 500
8. Soaked in Ill I and expanded barium nitrate therein.
An aqueous solution of 3 g of 1001111 dissolved in distilled water was added dropwise. After stirring gently for about 20 hours to sufficiently adsorb barium on the carrier, the catalyst was filtered off and heated at 110°C for 4 hours.
It was dried for 1 hour and then smoked at 500°C for 5 hours.

This catalyst was again immersed in 500 ml of distilled water, and an aqueous solution of 0.87 g of iridium chloride dissolved in 100 ml (7) of distilled water was added dropwise thereto, stirred gently for about 20 hours, and then filtered. The catalyst was dried for 4 hours at C. This catalyst is referred to as catalyst A. Catalyst A contains Q, 5 wt% of iridium, and 5 wt% of barium.

Catalysts supporting magnesium, calcium, strontium, etc. were prepared in the same manner as above using aqueous solutions of magnesium acetate, calcium nitrate, and strontium acetate, respectively, and then supported on iridium. These catalysts are designated as catalysts B1 and D, respectively. Catalysts 13, C, and D each contain 5 wt% of iridium Q and 5 wt% of an alkaline earth metal. For comparison, a catalyst in which only iridium was supported on 0.5 wt % alumina without supporting any alkaline earth metal was also prepared. Catalysts A, B, C1D, and E, with this catalyst as catalyst E, were packed in a flow-type fixed bed reaction tube,
After reduction at 500 °C for 3 hours, toluene was used as the feedstock at a pressure of 10 K g/ClTl2, a liquid space velocity of 1.0 volume/volume per hour, a hydrogen ratio of 5 moles 1 mole, and a reaction temperature of 45
The reaction was carried out at 0°C. 100 hours after the start of the reaction, the coke was burned for 5 hours at 500'O with nitrogen gas containing 2% oxygen to regenerate the catalyst. Table 1 shows the toluene conversion rate and benzene selectivity at 6 hours, 100 hours after the start of the reaction, and 6 hours after catalyst regeneration. From Table 1, compared to catalyst E for comparison, catalysts A, B, C, and D were clearly recyclable and had less activity loss.

Table 2 shows the average particle diameters of the iridium metal particles of the new catalysts A1BXCXD and E obtained by the hydrogen adsorption method and the iridium metal particles after regeneration. The hydrogen adsorption method referred to here is the
f Co11oid and InterfaceSc
The method described in ``Ience'' magazine, Vol. 34, No. 093, page 419 et seq. The outline of the process is to use a constant volume gas adsorption measurement device, collect the catalyst that has been reduced at 450"O for 2 hours into a sample tube, and store it at room temperature for about 200+n hours.
The surface oxygen is reduced under hydrogen pressure of nm1-(, and further 45
After vacuum degassing for about 2 hours at 0°C, return to room temperature (25'Q±2
Measure the amount of hydrogen adsorption (°C).

The metal particle size is determined from the measured amount of hydrogen adsorption using formula (]) and formula (2). In formulas (1) and (2), ■ is the measured hydrogen adsorption amount (1111/g), S is the iridium metal surface area (cm2/g), and N is the Ahokadro number (6,02 x 10
23), σ is the covered area per hydrogen molecule (12X1.
0-16CI]]2), W is the iridium loading rate (weight/
weight), 1) is the iridium metal particle size (^), and d is the iridium metal particle size (22,4 g/cm3).

V N・σ S-Kure Goryofu ×, Ya Formula (1) D knee
O3 formula (2) -d Table 2 Measurement results of metal particle size (λ) Catalyst E (!: Compared to catalysts A, B, and C1D, the change in particle size after regeneration is small, indicating that the aggregation of iridium metal particles It turns out that there are few.

(1 other person)

Claims (1)

[Claims] ■ Iridium and alkaline earth metal on an alumina phase?
A hydrodealkylation catalyst consisting of ζ. 2. The catalyst according to claim 1, wherein the alkaline earth metal is one or more metals selected from the group consisting of magnesium, calcium, strontium, and barium. 3. The catalyst according to claim 1 or 2, wherein the iridium on the alumina support is highly dispersed with an average particle size of I5 to 35A as analyzed by hydrogen adsorption method. 4. Production of a hydrodealkylation catalyst according to claims 1 to 3, characterized in that an alkaline earth metal is first supported on an alumina carrier, calcined, and then iridium is supported. Method. 5 Amorphous type I alumina as an alumina support, surface area 50 to 300 m2/g, pore volume 02 to o,
The method for producing a hydrodealkylation catalyst according to claim 4, which uses a catalyst having a physical property of 8 ml/g. 6. The method for producing a hydrodealkylation catalyst according to claims 4 to 5, which uses water-soluble salts of alkaline earth metals and iridium. 7 Using the hydrodealkylation catalyst according to claims 1 to 3, at a pressure of 5 to 30 Kg/cm
Hydrodesorption of alkyl aromatic hydrocarbons under the conditions of 2 (J), liquid hourly space velocity of 0.1 to 3.0 vol/vol, hydrogen/feedstock ratio of 2 to 20 mol 1 mol, and a magnification of 400 to 500 ''0. Alkyl method.