JPS59189935A - Ethanol reforming catalyst - Google Patents

Abstract

PURPOSE:To obtain an ethanol reforming catalyst developing high activity and high selectivity at a low temp., free from carbon precipitation and having long life, by allowing a carrier containing rutile type titania to support one or more of a metal selected from a group consisting of platinum and Pd. CONSTITUTION:A rutile type titania-containing carrier is allowed to support one or more of a metal selected from a group consisting of platinum and Pd. The above mentioned carrier is easily obtained by baking anatase type titania or one prepared by coating alumina with titania at 600 deg.C or more. In the next step, the noble metal is supported by the carrier according to such a method that the carrier is immersed in an aqueous solution containing a compound, for example, a noble metal nitrate and, after baking, the baked supported carrier is further subjected to hydrogen reducing treatment. Thus obtained catalyst is excellent in reaction for reforming ethanol to gas containing H and CO and shows high activity and high selectivity at a low temp., for example, at 300 deg.C while prevented from carbon precipitation and develops long life.

Description

[Detailed Description of the Invention] The present invention relates to an ethanol reforming catalyst.
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More specifically, the present invention provides a catalyst for reforming ethanol into a gas containing hydrogen and carbon oxide, which exhibits high activity and selectivity at low temperatures, and has a long life without carbon deposition.

Currently, crude oil and petroleum products made from it are used as raw materials for producing liquid fuel, gaseous fuel, and reducing gas used in power generation boilers, internal combustion engines, etc., but due to the recent rise in crude oil prices, As fuels become more diversified, ethanol, which can be synthesized from fermentation reactions of natural biomass resources or from fossil fuels other than crude oil, is attracting attention.

Furthermore, since ethanol is reformed into a gas containing hydrogen and carbon oxide at a much lower temperature than naphtha, it has the advantage that waste heat can be used as a heat source for reaction heat.

At this time, the generated reformed gas has the advantage that the calorific value of the reformed gas increases by the amount equivalent to the endothermic amount of the reforming reaction (approximately 13 Kcal/mob). When applied to an internal combustion engine with an octane rating and high output design, it has the advantages of increasing the compression ratio, improving thermal efficiency, and eliminating emissions of aldehydes when ethanol is burned, resulting in clean combustion.

When carrying out a reforming reaction of ethanol using exhaust gas heat from an internal combustion engine, the exhaust gas temperature ranges from room temperature to 8.
Since the temperature changes to about 0ρ℃, reforming can be carried out over a wide temperature range with a small amount of catalyst that can be installed in an internal combustion engine, and even if the temperature is at a high temperature of about 800℃, for example, the reforming can be carried out. A stable catalyst that does not deteriorate in performance is required.

Conventionally, platinum metal elements such as platinum, base metal elements such as copper, nickel, chromium, zinc, and their oxides are supported on a carrier such as alumina (hereinafter referred to as Az2O3) as a catalyst for reforming ethanol. However, to date, these catalysts still have many problems, such as poor low-temperature activity and lack of heat resistance.

Among the above-mentioned conventional catalysts, catalysts in which platinum is supported using γ-Atzo3 or anatase-type titania as a carrier have low selectivity in which only the desired reaction (2) occurs, and ethene, ether, There is a problem in that side reactions (2), which generate aldehydes and the like, are likely to occur.

Reaction ■ C2H50H-+ C○ + H2-1-C! H4 Side Reaction■ In order to solve the above problem, the present inventors have developed a siltyl-type titania support by heat-treating at high temperature anatase-type titania support, which has a large specific surface area and has an acidic action, which has been conventionally used as a catalyst support. Although the specific surface area becomes smaller when crystallization transition occurs, the acidic effect is almost eliminated and the platinum particles dispersed on the surface of the carrier are less likely to agglomerate, and various experimental studies were conducted. As a result, platinum,
The present inventors discovered that a catalyst supported on a core of a noble metal such as palladium has excellent activity and selectivity in an ethanol reforming reaction, leading to the completion of the present invention.

The method of the present invention is characterized in that a catalyst in which a noble metal such as platinum or palladium is supported on a carrier containing rutile-type titania is used as an ethanol reforming catalyst.

Here, the carrier containing rutile-type titania is anatase-type titania or an alumina carrier coated with titania, etc. at a temperature of 600°C or higher, preferably 800°C.
It can be easily obtained by firing at a temperature range of ~1000°C.

Next, the method of supporting the noble metal on the carrier obtained in this way is a conventionally used method without any problem, for example, the carrier is immersed in an aqueous solution of a compound such as a nitrate or a danide of a noble metal, and then calcined. If it is further subjected to hydrogen reduction treatment, a catalyst on which precious metals are supported can be obtained.

The catalyst obtained as described above converts ethanol into hydrogen, −
It has excellent selectivity for the desired reaction in the reaction of reforming gas containing carbon oxide, and exhibits high activity and selectivity at a low temperature of 300°C.

Hereinafter, the present invention will be specifically explained with reference to Examples.

[Example 1] An anatase type titania carrier (bellet) having a particle size of 2 to 4 mm was calcined at 800°C for 20 hours to obtain a rutile type titania carrier. The crystal transition to rutile type was identified by X-ray diffraction.

The rutile-type titania support was immersed in an aqueous solution of platinum and hibaradium nitrates and subjected to hydrogen reduction treatment to prepare catalysts 1 and 2 each carrying platinum and palladium at a concentration of 3% by weight.

In addition, using the same method as for Catalyst 1 above, the platinum concentration was 0.5, 0.
1% by weight of catalysts 3 and 4 were prepared, respectively.

The activity of these catalysts was evaluated under the conditions shown in Table 1, and the results are shown in Table 2. Table 2 also shows the evaluation of a catalyst containing platinum (133% by weight) using an anatase-type titania carrier as a comparative catalyst.

Table 1 Table 2 [Example 2] As a comparative catalyst, a catalyst was prepared in which platinum was supported on a conventional anatase-type titania carrier by weight of a3. For this catalyst and the catalyst in Example 1VC, the reaction temperature was set at 500°C.
When the activity was evaluated under the same conditions as in Table 1 except that the conditions were changed, the results shown in Table 6 were obtained.

Table 3 In addition, the reaction temperature of catalyst 1 was kept constant at 500°C, and L, H,
When the catalyst was operated continuously for 20 hours at S, V, and 2.5 h-1, almost no carbon was observed to be deposited on the catalyst.

In the examples, granular catalysts are described, but
It goes without saying that the shape of the catalyst is not particularly limited, and that catalyst shapes such as nicomb shape and plate shape may be used.

Further, in the embodiment, the case where ethanol alone is used is described, but ethanol reforming may be carried out in the coexistence with a gas containing water vapor, 9 gas, etc.

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Claims (1)

[Claims] An ethanol reforming catalyst characterized in that one or more metals from the group consisting of platinum and palladium are supported on a carrier containing rutile-type titania.