JP3364254B2 - Catalyst for combustion of hydrocarbons - Google Patents

Description

Detailed Description of the Invention

The present invention relates to a method for producing a hydrocarbon combustion catalyst , which exhibits high combustion activity when used in a high temperature combustor for heating or heating, and has excellent heat resistance. And a method for producing a catalyst for burning hydrocarbons.

[0002]

2. Description of the Related Art In recent years, with increasing interest in energy saving, resource saving, or environmental protection, a catalytic combustion system in which a mixture of hydrocarbon fuel and air is burned at a high temperature using a catalyst has been attracting attention. In the catalytic combustion system in which hydrocarbons are completely oxidized into carbon dioxide and water vapor in the presence of oxygen-containing gas, the catalyst is platinum group metals such as platinum and palladium, and heat-resistant inorganic oxides such as alumina and silica. A catalyst supported on a physical carrier is widely known. As the heat-resistant inorganic oxide carrier, alumina having boehmite as a starting material has been favored because it has little change in physical properties even when exposed to high temperature and has little strength strain even after heat transfer. Further, researches for further improving the heat resistance of the catalyst carrier have been continued. For example, in JP-A-60-222145, a rare earth element such as lanthanum (La) is added to alumina used as a carrier. , Techniques for improving the heat resistance of combustion catalysts have been proposed. By the way, in a high temperature combustor in which the combustion gas outlet temperature is 1000 ° C. or higher, it is not uncommon for the catalyst layer internal temperature to exceed 1200 ° C. When a conventional combustion catalyst is used in such a high temperature combustor,
Even if the carrier is alumina which is particularly excellent in heat resistance, the crystal structure of alumina is transferred from γ-alumina to α-alumina, and the surface area of the carrier, the pore volume, and the wear resistance are reduced, so that the catalyst There was a problem that the combustion activity of was deteriorated.

[0003]

It is generally considered that the activity of the combustion catalyst depends on the dispersibility of the active metal component in the carrier, and the dispersibility depends on the surface area of the carrier. Therefore, in developing a combustion catalyst that can be used in high-temperature combustors,
An important issue is the development of a heat-resistant catalyst carrier that retains a high surface area even at high temperatures of approximately 1000 ° C or higher. The present invention provides a novel hydrocarbon combustion catalyst that can be sufficiently used even in a high temperature combustor without the problems pointed out in the conventional combustion catalysts described above.

[0004]

The present inventors have SUMMARY OF THE INVENTION As a result of intensive studies on a catalyst for hydrocarbon combustion, responsible platinum group metal aluminosilicate preparative catalysts carriers produced in a certain way
The inventors have found that a catalyst for burning hydrocarbons having high combustion activity and excellent heat resistance can be obtained by the method of holding and calcining at a specific temperature, and completed the present invention. That is, the method for producing a hydrocarbon combustion catalyst according to the present invention has 2 carbon atoms.
The 20 aluminum alcoholates or mixing orthosilicate after hydrolysis with deionized water, or by hydrolyzing the previous SL aluminum alcoholate of Te in deionized water containing orthosilicic acid, drying the obtained suspension to the content of the silica component is prepared aluminosilicate is from 0.5 to 50 wt%, the aluminosilicate
5 fired at 00 of less than 1100 ° C. temperature, by supporting a catalyst <br/> carrier platinum group metal thus obtained, baked at 700 to 1200 ° C.
It is characterized by performing . Usually, aluminum silicate is prepared by using water-soluble alkali metal aluminate and silicic acid as the alumina source and the silica source, respectively. However, the aluminosilicate of the present invention contains carbon as the alumina source. The number 2 to 20 of aluminum alcoholate is used, and orthosilicic acid is used as the silica source. The manufacturing method of such aluminosilicate is
Is disclosed in JP-A-2-144145, according to the method, the amount of silica component in the aluminosilicate, the amount of orthosilicic acid to be mixed with the aluminum alcoholate can be adjusted arbitrarily. But,
In the aluminosilicate of the present invention, the content of the silica component is in the range of 0.5 to 50% by weight, preferably 5 to 20% by weight. As aluminum alcoholate,
C ₂ which is produced during the synthesis of Ziegler alcohol
~C mixed alcoholate can be used with a carbon number distribution of _20, also with an alcohol in the range of 2 to 20 carbon atoms, various aluminum alcoholate which is prepared from the reaction of aluminum can be used.

A typical method for producing a combustion catalyst according to the present invention will be described. First, deionized water is added to an aluminum alcoholate having 2 to 20 carbon atoms (aluminum content is 0.1 to 10% by weight). And hydrolyze the alcoholate at a temperature of 60-150 ° C. Then, a predetermined amount of orthosilicic acid (silica content: 0.1 to 5% by weight) is mixed with this to prepare a suspension.
After spray-drying at a temperature of ℃, the dried powder obtained is formed as it is, or after being formed into any shape and size as desired, 50
0 to less than 1100 ° C , preferably 700 to 1100 ° C
The catalyst carrier is obtained by calcining at a temperature of 700 to 1000 ° C. Alternatively, the deionized water used to hydrolyze the aluminum alcoholate may be premixed with a predetermined amount of orthosilicic acid. In this case, of course, when orthosilicic acid is mixed after the hydrolysis of aluminum alcoholate, the orthosilicic acid is preferably purified (deionized) by an ion exchange device. The combustion temperature of aluminosilicate has an important influence on the performance of the finally obtained combustion catalyst, and its temperature product decreases, while at 1100 ° C or higher, the surface area required as a catalyst carrier is changed to aluminosilicate. I can't hold it. The catalyst carrier of the present invention may contain a small amount of a refractory inorganic oxide such as silica, magnesia, titania, etc., if necessary, and the catalyst carrier of the present invention can be used as a powder or extruded product. , Tablets, spheres, granules, honeycomb structures, etc. can be formed in any shape having any size.

The catalyst carrier of the present invention is then loaded with a platinum group metal as an active metal component. Platinum group metals include ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (I
One or two or more of r) and platinum (Pt) can be used, but in general, any one of palladium, rhodium and platinum is preferable, and palladium is particularly preferable. Any method known in the art can be used for supporting the platinum group metal on the catalyst carrier, but an impregnation method in which the catalyst carrier is immersed in an aqueous solution containing a platinum group metal salt is preferably used. As the platinum group metal, chloride, nitrate, acetate and the like are preferable. The amount of platinum group metal supported as an oxide is preferably 0.01 to 20% by weight of the catalyst weight (total weight of catalyst carrier and active metal),
0.1 to 10% by weight is particularly preferred. After supporting the platinum group metal, the temperature is preferably 200 to 500 in air.
And dried in air, preferably at a temperature of 700 to 12
The combustion catalyst of the present invention can be obtained by firing at a temperature of 00 ° C, more preferably 900 to 1200 ° C. When the calcination temperature is less than 700, when the obtained catalyst is used at a temperature of 700 ° C. or higher, the initial activity is
When the temperature is higher than 1200 ° C. , the surface of the catalyst is reduced to agglomerate the supported active metal components, and the catalytic activity is lowered. INDUSTRIAL APPLICABILITY The catalyst of the present invention can be used as a catalyst for complete oxidation of various hydrocarbons, and in particular, high temperature fueled by hydrocarbons such as methane, propane, butane, city gas, natural gas, kerosene, and light oil. It is suitable as a catalyst for a combustor.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Example-1 The aluminosilicate used as the catalyst support material in the present invention is produced as follows. To 450 g of mixed alcoholate (aluminum content of 6.0 wt.%), 500 g of deionized water was added, and the mixture was hydrolyzed by stirring at 90 ° C. for 15 to 60 minutes. The aqueous alumina suspension separated from the alcohol by this hydrolysis was deionized with an ion exchange device to obtain orthosilicic acid (silica content 3 wt.%) 190
g were mixed. 300-60 solid-containing suspension obtained
Spray drying was carried out at a temperature of 0 ° C. by a conventional method to obtain an aluminosilicate powder. As a result of compositional analysis, the silica content in this aluminosilicate was 10% by weight. The above-mentioned aluminosilicate obtained by spray-drying in air 7
After firing at 00 ° C for 2 hours. The calcined aluminosilicate support is dipped in an aqueous solution of palladium chloride to impregnate it with palladium, which is then dried once and then dried in air.
By firing at 00 ° C. for 2 hours, a finished catalyst A carrying 1 g of palladium in terms of metal per 100 g of aluminum silicate support was obtained. Comparative Example-1 100 g of aluminosilicate carrier was prepared in the same manner as in Example-1, except that only the firing temperature of aluminosilicate and the firing temperature after supporting palladium were changed as shown in Table 1.
As a result, a finished catalyst B carrying 1 g of palladium as a metal was obtained. Comparative Example-2 100 g of aluminosilicate support was prepared in the same manner as in Example-1, except that only the firing temperature of aluminosilicate and the firing temperature after supporting palladium were changed as shown in Table 1.
As a result, a finished catalyst C supporting 1 g of palladium as a metal was obtained. Comparative Example- 3 Aluminosilicate support 100 g was prepared in the same manner as in Example-1, except that only the firing temperature of aluminosilicate and the firing temperature after supporting palladium were changed as shown in Table 1.
A finished catalyst D was obtained, in which 1 g of palladium was supported as a metal. Comparative Example 4 Alumina prepared using boehmite as a starting material by a conventional method was calcined in air at 700 ° C. for 2 hours, the alumina powder was dipped in an aqueous palladium chloride solution to impregnate palladium, and then dried once. 12 in the air
Alumina carrier 10 was obtained by firing at 00 ° C. for 2 hours.
A finished catalyst E supporting 1 g of palladium per metal of 0 g was obtained. Comparative Example 5 Alumina carrier 100 was prepared in the same manner as Comparative Example 4 except that only the firing temperature after supporting palladium was changed as shown in Table 1.
A finished catalyst F was obtained in which 1 g of palladium was supported per g.

The catalysts obtained in the above Examples and Comparative Examples were
Each cylinder combustor was filled with 0.3 g and the volume of 1.5%
Propane / air mixed gas containing lopan per hour
Introduced 9 liters, ignition temperature and propane conversion of 50%
By measuring the reaction temperature at which
The burning activity was evaluated. The results are shown in Table 1. In addition,
The conversion rate depends on the propane concentration in the combustor inlet gas and the outlet gas.
It was calculated from the difference with the propane concentration of. In addition, the touch shown in Table 1
The surface area of the medium is 200 ° C for the samples taken from each catalyst.
After drying, nitrification under the conditions of liquid nitrogen temperature and relative pressure 0.3.
It was calculated from the elementary adsorption amount by the BET one-point method.                                   Table 1 CatalystA  B  C  D  E  F Carrier AS AS AS AS A A   Carrier firing temperature (℃) 700 1200 1200 1450 700 700   Catalyst firing temperature (℃) 900 900 1200 1200 1200 900   Catalyst surface area (m²/ g) 185 103 81 7 6 114 Propane combustion activity   Ignition temperature (℃) 295 305 305 335 340 340 320 T50 (℃) 385 390 395 530 565 430 Note) The amount of palladium supported on each catalyst is 1 for metal
wt%. AS = aluminosilicate (indicates silica content of 10 wt%. A = indicates alumina. T50 = temperature at which propane conversion is 50%.

As is clear from Table 1, the aluminosilicate-supported catalyst of the present invention maintains a high combustion activity even when calcined at a high temperature of 1200 ° C., as compared with the conventional alumina-supported catalyst. However, it can be seen that the heat resistance is excellent. Table 2 for Catalyst C and E, respectively the firing conditions were conducted in the same manner as combustion activity test and the upper Symbol Change to 96 hours at 1200 ° C. in air, the actual <br/> shows the experimental results in Table 1 It is compared with the test results. Table 2 Catalyst C Catalyst E Catalyst calcination temperature (° C) 1200 1200 1200 1200 1200 Catalyst calcination time (hr) 2 96 2 96 Catalyst surface area 81 29 6 1 Propane combustion activation ignition temperature (° C) 305 330 330 340 355 T50 (° C) 395 430 as is clear from 565 610 top Symbol table 2, the catalyst C in which the a luminometer silicate and carrier be fired even 96 hours at 1200 ° C.,
While it still retains a relatively high combustion activity, the conventional alumina-supported catalyst E has a significantly reduced combustion activity.

[0010]

The combustion catalyst of the present invention is obtained by using aluminum alcoholate as an alumina source and orthosilicic acid as a silica source, and an aluminosilicate which maintains a high surface area even when it is fired at a high temperature. Due to its use as a carrier, it exhibits satisfactory combustion activity even in a high temperature combustor in which the internal temperature of the catalyst layer reaches 1200 ° C.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Asami Takeuchi 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Japan Petroleum Co., Ltd. Central Research Laboratory (56) Reference Japanese Patent Laid-Open No. 2-144145 (JP, A) Kaihei 3-257060 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B01J 21/00-37/36

Claims (2)

(57) [Claims] 1. A mixing or orthosilicate aluminum alcoholate C2-20 after hydrolysis with deionized water, or the aluminum alcoholate before Symbol Te deionized water containing orthosilicic acid hydrolysis, Profit
The resulting suspension is dried to a silica content of 0.5.
The aluminosilicate is 50 wt% was prepared, this aluminosilicate was calcined at a temperature of less than 5 00~ 1100 ° C., allowed to support platinum group metal thus obtained catalyst carrier 7
A method for producing a hydrocarbon combustion catalyst , which comprises calcination at 00 to 1200 ° C. 2. The aluminosilicate of 700 to 10
The firing according to claim 1, wherein the firing is performed at a temperature of 00 ° C.
A method for producing a catalyst for burning hydrocarbons as described above.