JPH04363140A - Catalyst and its production - Google Patents

Abstract

PURPOSE:To efficiently produce a catalyst used for steam reforming of hydrocarbon, etc., using a heat resistant carrier such as alumina or silica and Ni as the principal catalytic component, having high activity and hardly undergoing deposition of carbon. CONSTITUTION:A soln. contg. Ni is impregnated into a catalyst carrier, dried and subjected to reduction treatment. The carrier is then heat-treated at 30-110 deg.C in a CO atmosphere and fired at 150-600 deg.C.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a catalyst in which nickel is supported on a support such as alumina, which is used for producing a mixed gas containing hydrogen and carbon monoxide by steam reforming hydrocarbons, etc. Regarding.

0002

[Prior Art and Problems to be Solved by the Invention] It is already known to use a heat-resistant carrier such as alumina or silica for steam reforming of hydrocarbons, etc., and to use a catalyst containing nickel as the main component for catalytic activity. Are known. However, these conventional catalysts are required to have higher activity and to be less likely to cause carbon deposition. As a solution to this problem, the present applicants previously filed a patent application filed on 2-16
No. 4432 proposed a steam reforming catalyst in which nickel oxide was supported on an alumina porous material mainly composed of α-alumina, and part or all of the charged nickel was converted to nickel aluminate. This catalyst seems to have solved the above problem by improving the dispersion of nickel, but further studies revealed that high-temperature treatment was required to generate nickel aluminate and that nickel aluminate was reduced to nickel before use. There was some problem in that it took a long time.

0003

[Means for Solving the Problems] As a result of further research into solving this problem, the present inventors have completed the present invention. That is, in the present invention, a catalyst carrier is impregnated with a solution containing nickel, dried, and then subjected to reduction treatment, heat treated at a temperature of 30 to 110 °C in a carbon monoxide atmosphere, and then heated at a temperature of 150 to 600 °C. The calcined catalyst and the catalyst carrier are impregnated with a nickel-containing solution, dried, and then subjected to a reduction treatment to a temperature of 30 to 110% in a carbon monoxide atmosphere.
The present invention relates to a method for producing a catalyst, which is characterized by heat treatment at a temperature of 150 to 600 °C, followed by calcination at a temperature of 150 to 600 °C.

Supports suitable for the present invention include SiO2, MgO
, ZrO2, a mixture of Al2O3 and SiO2, zeolite, etc., but alumina is a typical example, and in particular, it is a high-purity aluminum oxide porous body with a porous structure with an apparent porosity of 50 to 80%, preferably 50 to 70%. The pore size is 0.1 to 0.5 μm, the pore volume is 0.2 ml/g or more, and the pore size is 0.5 μm.
The pore volume within the range of μm or more and 10 μm or less is 0.
05 ml/g or more, and α-alumina containing 98% by weight or more of aluminum oxide in its components is preferably used. By providing nickel as an active component on such a carrier and then performing the heat treatment and calcination specific to the present invention, the nickel is generally 3 to 20% by weight, preferably 5 to 20% by weight, based on the total weight of the catalyst, in terms of nickel oxide. When the content is 15% by weight, particularly preferably 5 to 10% by weight, the catalyst of the present invention having excellent performance in steam reforming of hydrocarbons etc. can be obtained. The performance of the catalyst according to the present invention is excellent because
By heat treatment with carbon monoxide (hereinafter abbreviated as CO treatment), the supported nickel component becomes a nickel carbonyl compound, which is then highly dispersed as nickel metal on the support by subsequent firing, yielding highly active fine nickel particles. It seems to be for a reason.

The catalyst of the present invention is suitable for reforming lower hydrocarbons such as methane with steam. For example, α-
The means of adding the nickel component to the alumina porous body is not particularly limited, but it is necessary that the nickel component be homogeneously distributed in the porous structure of the carrier with as large a surface area as possible. , a well-known method of immersion in a nickel salt solution is suitable. For example, α-alumina having the above properties is immersed in an aqueous solution of nickel nitrate, and after the aqueous solution penetrates into the center of the porous material, it is naturally dried, and then forced drying at about 100 to 130°C by a conventional method. After calcination and reduction, the catalyst of the present invention is obtained by heat treatment in a carbon monoxide atmosphere and then calcination. This heat treatment may be carried out, for example, by heating in a carbon monoxide atmosphere, preferably in a closed system with internal circulation. Further, it is preferable to first create a vacuum (reduced pressure) atmosphere before introducing the carbon monoxide atmosphere. In the case of heat treatment under normal pressure, the heat treatment temperature is preferably 30 to 110°C, more preferably 50 to 90°C, and most preferably 60 to 80°C. The heat treatment time can be shortened by increasing the pressure. A suitable heat treatment time is 1 to 10 hours. The more nickel supported, the lower the heat treatment temperature, the longer the heat treatment time. In order to obtain a catalyst that is calcined at 70 to 80°C and supports about 8% nickel in terms of nickel oxide, it is sufficient to carry out the heat treatment for about 4 to 8 hours. After this, the heating temperature is increased to 150°C or higher, preferably 200°C or higher, most preferably 250 to 60°C.
The catalyst of the present invention is obtained by maintaining the temperature at 0° C. for 1 to 2 hours or more and calcining it, then purging the system with nitrogen and lowering the temperature to room temperature. If the calcination temperature is lower than this range, the improvement in catalytic activity will be small, and if it is higher than this range, a long time will be required for the pre-reduction treatment when using the catalyst, both of which are unfavorable.

The degree of fineness of nickel in the catalyst after CO treatment and subsequent calcination can be ascertained by the following method. That is,
X-ray diffraction analysis of the catalyst was performed, and the half-width (in radians) of the zero-valent nickel peak appearing at 2θ = 44.5° was found to be
If the ratio of the half-value width of the CO-treated and fired product to the half-value width of the CO-treated and unfired product is W ratio, W
The ratio is preferably 1.5 or more, more preferably 1.7 or more. Generally, the object of the present invention can be achieved by setting the W ratio to about 3.0 to 5.0. For example, when the alumina support containing nickel salt was subjected to a conventional reduction treatment, the nickel particle size in the catalyst was determined to be 1 according to the half-width method of X-ray diffraction.
000 to 1500 Å (angstroms). The catalyst of the present invention is commercially available as a conventional product without the addition of alkali metal elements, etc., because fine active nickel generated by CO treatment and calcination of reduced nickel by a conventional method is uniformly dispersed in the carrier when the catalyst is used. It is thought that the decrease in activity due to carbon precipitation is extremely small compared to the product. Although the addition of alkali metal elements etc. is not essential to the present invention,
These additions may be made within a range that does not impair the purpose of the present invention.

[0007]

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

Example 1 Pore volume of 0.22 with pore diameter of 0.1 to 0.5 μm
ml/g, a pore size of 0.5 μm or more and 10 μm or less, and a pore structure with a pore volume of 0.07 ml/g, an average particle size of 5 mm, and a purity of 98% or more. NO3)2.6H2O] 1.3kg
was dissolved in water to make a total volume of 1 liter, then air-dried for a day and night, then dried at 120 °C for 6 hours, further heated, and heated to 750 °C for 5 to 6 hours.
and held at this temperature for 5 hours. After that, the heating temperature was raised to 800 °C, and the ratio of the number of moles of water vapor to the number of carbon atoms in methane was S/C = 7.0 using water vapor and methane.
, reduction was carried out for 20 hours at a space velocity SVo=1000 h-1. Furthermore, the catalyst was once placed under a reduced pressure of 5 mmHg or less for 1 hour, and then heated at a temperature of 70 to 80°C under a carbon monoxide atmosphere.
After maintaining the pressure at 0.1 kg/cm2·G for 4 hours, the mixture was calcined at 280° C. for 1 hour and replaced with nitrogen to obtain the catalyst of the present invention. This catalyst contained 8.6% by weight of nickel in terms of nickel oxide. W ratio is 1.7
Met. This is abbreviated as catalyst A. Catalyst A-0 is obtained by omitting the CO treatment and subsequent treatments in the production of the above catalyst A.
It is abbreviated as In addition, a catalyst with the same nickel content as Catalyst A obtained in the same manner as Catalyst A except that the CO treatment temperature and CO treatment time were 20 to 30°C and 10 hours, respectively, was abbreviated as Catalyst A-1. . The W ratio of A-0 and A-1 is 1.
It was 0. Furthermore, a catalyst with the same nickel content obtained in the same manner as Catalyst A except that the CO treatment temperature and CO treatment time were 110 to 120 °C and 4 hours in the production of Catalyst A is abbreviated as Catalyst A-2. . The W ratio of A-2 is 1.3
Met. After each of the above catalysts was filled into a reaction tube with an inner diameter of 12.3 mm, the temperature of the catalyst layer was raised to 800 °C, and the ratio of the number of moles of water vapor to the number of carbon atoms in methane was S/C = 7 using water vapor and methane. .0, space velocity SVo=100
After being reduced at 0 h-1 for 4 hours, it was used in a steam reforming experiment. The reaction conditions were S/C=3.0, reaction pressure P=0.
Methane and steam were supplied into the reaction tube at 1 kg/cm2·G and SVo=8000 h −1 . The reaction product was obtained via a condenser and a gas meter, and analyzed by gas chromatography. Continue this reaction for 5
It was carried out for 00 hours. Table 1 shows the experimental results. In cases where the activity decreased significantly, the experiment was discontinued after 100 hours. Note that the reaction time 0 is the time when the reaction starts immediately after reduction.

[0009]

[Table 1]

[0010] The experimental results for catalyst A showed a value close to equilibrium, and the activity was high. Further, almost no decrease in activity was observed. Catalysts A-0, A-1, and A-2 showed almost high initial activity, although there was some variation. However, the activity decreased significantly.

Claims (3)

[Claims] Claim 1: A catalyst carrier is impregnated with a solution containing nickel, dried, subjected to reduction treatment, heat treated at a temperature of 30 to 110 °C in a carbon monoxide atmosphere, and then heated to 15 °C.
Catalyst calcined at temperatures between 0 and 600°C. 2. The catalyst according to claim 1, wherein the support is alumina. 3. A catalyst carrier is impregnated with a nickel-containing solution, dried, subjected to reduction treatment, heat treated at a temperature of 30 to 110 °C in a carbon monoxide atmosphere, and then
A method for producing a catalyst, characterized by firing at a temperature of 0 to 600°C.