JPS5987045A - Catalyst for reforming methanol - Google Patents

Abstract

PURPOSE:To remarkably enhance activity and durability to the titled catalyst, by a method wherein Ce and/or Pr is deposited on inorg. oxide as Ce-oxide and/ or Pr-oxide and, after reduction, Pt and/or Pd is adhered to treated inorg. oxide. CONSTITUTION:An inorganic oxide particle based on activated alumina is impregnated with a Ce-compound and/or a Pr-compound and the impregnated particle is baked at 450-600 deg.C for 1-3hr in air to deposit Ce and/or Pr as oxides. The oxide to be deposited is pref. used in an amount of 0.1-10wt% on the basis of a metal. Thus obtained carrier is required to be treated with a reducing agent and, therefore, pref. treated with an aqueous solution containing 1.0wt% or more of hydrazine and the treated one is dried after treatment. In the next step. Pt and/Pd is deposited on the treated carrier as catalytic metals by a usual method and the supporting amount of each catalytic metal is pref. adjusted to a range of 0.1-1.0wt% expressed in terms of the metal. By this method, the activity and the durability of the titled catalyst are remarkably enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a methanol reforming catalyst for reforming methanol into a gaseous form of hydrogen and carbon monoxide.

Conventionally, as a methanol reforming catalyst, a catalyst has been proposed in which a platinum group element such as platinum or a base metal element such as copper and its oxide are attached to an inorganic oxide mainly composed of activated alumina.

However, when such conventional methanol reforming catalysts are used in internal combustion engines, platinum, copper, etc. agglomerate, resulting in a significant decrease in activity when used for a long time.
There was a problem of lack of durability.

This invention was made in view of these conventional problems, and involves adding at least one element selected from cerium and praseodymium to an inorganic oxide whose main component is activated alumina. The purpose of the present invention is to solve the above problems by treating the particulate carrier deposited as an oxide with a reducing agent and then depositing at least one metal selected from the group consisting of platinum and palladium.

Tomo Kito's tactile agent consists of attaching at least one element selected from the group consisting of cerium and praseodymium as an oxide to a preferably granular inorganic oxide mainly composed of activated alumina, and adding a reducing agent to the inorganic oxide. One of the major characteristics is that the cerium and/or praseodymium oxide is attached as a granular carrier by using the co-treated particles as a granular carrier. , about 4.50-600' in air flow
This can be carried out by baking at a temperature of C for preferably 1 to 3 hours to form an oxide. The adhering oxide is preferably 0.1 to IO weight % in terms of metal, and 0.1
When the amount is less than -110% by weight, the performance of the resulting catalyst is reduced. The support obtained in this way must be treated with a reducing agent, for which sodium borohydride (SBH1
0.5% by weight or more aqueous solution or 1.0% by weight of hydrazine,
The catalyst of the present invention, which is preferably treated with an aqueous solution of 14% or more and dried after the treatment, contains at least one selected from the group consisting of platinum and palladium as a catalytic metal on a carrier treated with a reducing agent as described above. It is made by depositing one type of metal by a commonly used method, and the amount of catalyst metal supported is preferably in the range of 0.1 to 1.0% by weight in terms of metal.

The catalyst of the present invention constructed as described above consists of a carrier in which at least one element selected from the group consisting of cesium and praseodymium is attached as an oxide to an inorganic oxide mainly composed of alumina. By treating it with a reducing agent before adhering the catalytic metal, its durability is further improved, making it extremely valuable in practical terms.

The present invention will be further illustrated by the following Examples, Comparative Examples and Test Examples.

Example 1 Granular carrier mainly composed of gamma alumina (particle size 1 to 3
mm) was impregnated with an aqueous cerium nitrate solution, dried, and
It was calcined in air at °C for 1 hour to obtain a carrier containing cerium oxide in an IM amount relative to alumina in terms of metal.

Next, the carrier obtained in this manner was treated with a 0.5% by weight aqueous solution of sodium borohydride (SBH), and then immersed in an aqueous solution of platinum or palladium chloride.
It was dried in an oven at 0°C until the water content was 10% by weight or less, and then steam-calcined at 550°C for 90 minutes to obtain a catalyst supporting 0.38% by weight of each of platinum and palladium. It was set as 2.

Example 2 A catalyst was produced in the same manner as in Example 1 except that the treatment was performed with a 1.0% by weight aqueous solution of hydrazine instead of the SBHO, 5% aqueous solution, and catalyst 8 was prepared with platinum supported. I used something as a catalyst.

Example 3 Catalysts were produced in the same manner as in Example 1 except that the catalyst was impregnated with an aqueous praseodymium nitrate solution instead of an aqueous cerium nitrate solution, and catalyst 5 supported platinum, and catalyst 6 supported palladium.

Example Φ Catalysts were produced in the same manner as in Example 3 except that a 1.0% by weight aqueous solution of hydrazine was used instead of the SBHO, 5M aqueous solution. Catalyst 7 supported platinum, and catalyst 7 supported praseodymium. was designated as catalyst 8.

Comparative Example 1 Granular carrier mainly composed of gamma alumina (particle size 1 to 8
Platinum or palladium was immersed in a chloride water bath, dried in an oven at 200°C until the moisture content was 10% by weight or less, and steam fired at 550°C for 90 minutes to remove platinum. , catalysts each supporting 0.38% by weight of palladium were obtained and designated as catalysts A and B.

Comparative Example 2 Granular carrier mainly composed of gamma alumina (particle size 1 to 8
A catalyst containing 9.0% by weight of copper was produced by immersing a plate in a copper nitrate solution in an aqueous solution, which was designated as Catalyst C. Copper immersion drying (moisture content 1 at 200'C in an atmosphere oven)
After that, steam calcination was performed at 550''C for 90 minutes.

Comparative Example 8 Catalysts were produced in the same manner as in Example 1, except that they were not treated with 5BE (0.5% by weight aqueous solution), and the one on which platinum was supported was used as a catalyst, and the one on which palladium was supported was used as catalyst E.

Comparative Example 4 Catalysts were produced in the same manner as in Example 8 except that they were not treated with a 5% by weight aqueous solution of SBHO, and the catalyst supporting platinum was designated as Catalyst F, and the catalyst supporting palladium was designated as Catalyst G.
And so.

Table 1 shows the measurement results of initial activity and activity after durability testing conducted under the following conditions for Catalysts 1 to 8 obtained from Examples 1-4 and Catalysts A to G obtained from Comparative Examples 1 to 4. The compositional analysis of the reformed gas was performed using a gas chromatograph.

Durability test conditions Catalyst amount 20m1 Catalyst bed temperature 400°C Space velocity 200011r-1 Durability time 200hr Methanol Activity evaluation of industrial methanol catalyst Use industrial methanol (100%) using an evaporator and set the catalyst bed temperature to 300°C・The decomposition rate of methanol when the evaporated methanol passes through the catalyst bed (
H2 concentration) was measured using a gas chromatograph. The amount of catalyst evaluated at the time of measurement was lQm (!.

The estimated space velocity is 2000 hr-1.

From the above table, it is clear that the methanol reforming catalyst of the present invention has significantly improved activity and durability compared to the catalyst of the comparative example.

Figure 1 shows the initial performance of hydrogen (H2
) Expressed as concentration. In Figure 1, line A is the performance of catalyst 1, line B is the performance of catalyst, line C is the performance of catalyst A, and line is the performance of catalyst C.
shows the performance of

Next, Figure 2 shows the performance after 200 hours of durability.
Shown at 2 concentrations. In Fig. 2, line A' represents the performance of catalyst l;
Line B' is the performance of catalyst, line C' is the performance of catalyst A, line D'
indicate the performance of catalyst C, respectively. It can be seen from FIGS. 1 and 2 that the catalyst activity of the present invention is extremely excellent.

[Brief explanation of drawings]

Figure 1 shows catalyst 1. A diagram showing the initial performance of catalysts A, C and D, Figure 2 is for catalyst 1. This is the weight resistance showing the performance of A, O, and D after 200 hours of durability. Figure 1

Claims (1)

[Claims] After treating with a reducing agent a granular carrier on which at least one element selected from the group consisting of cerium and praseodymium is attached as an oxide to an inorganic oxide mainly composed of activated alumina, platinum and praseodymium are added. A tactile material for methanol reforming characterized in that it is formed by adhering at least one metal selected from the group consisting of palladium.