JP2716092B2 - Hydrocarbon steam reforming method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for steam reforming of hydrocarbons, and more particularly, to a method in which a catalyst layer carrying a specific metal component is combined in a specific ratio to reduce the amount of the catalyst. The present invention relates to a method for reforming hydrocarbons with steam at a steam / carbon ratio.

[Problems to be Solved by the Related Art and the Invention] Conventionally, a steam reforming reaction of hydrocarbons, which mainly reacts with hydrocarbons and steam to convert them into hydrogen and carbon monoxide, uses a nickel-based catalyst or a noble metal-based catalyst. It has been done with.

For example, Japanese Patent Publication No. 53-12917 discloses a method using a nickel-based catalyst supported on an alumina carrier using metal nickel or the like as a catalytic active component.
No. 35 and JP-A-56-91844 disclose a method using a noble metal catalyst in which rhodium, ruthenium, platinum or the like is supported on a carrier such as alumina or zirconia.

In a reaction using a nickel-based catalyst, if the reaction is not performed at a high steam-carbon ratio (H ₂ O mole / C atom) of 3.0 to 6.0, the precipitation of carbon becomes large and the catalyst life is shortened. . In the reaction using a noble metal catalyst, the steel-carbon ratio is set to a low value of 1.5 to 3.0.
However, there is an advantage that the carbon deposition can be reduced and the catalyst life can be extended.
Noble metal based catalysts have the disadvantage of being very expensive and costly.

Further, the hydrocarbon steam reformer using these catalysts has the following problems.

That is, (1), most of the reforming reaction occurs at the inlet portion with respect to the flow direction of the catalyst layer, and the possibility of carbon deposition is large, and the catalyst is exposed to the most severe conditions and coking occurs.

(2) When the performance of the catalyst decreases due to carbon deposition,
The reaction temperature must be increased in order to maintain the amount produced by the reforming reaction. Then, the life of not only the catalyst but also the expensive reaction tube is rapidly shortened.

(3) Noble metal (rhodium, ruthenium, etc.) catalysts have higher activity and less carbon deposition than nickel-based catalysts and are excellent. However, if the reaction device is fully filled with the noble metal-based catalyst, the cost becomes extremely high. There are disadvantages. Therefore, this method is not industrial.

(4) If the steam / carbon ratio is increased to reduce carbon deposition, the consumption of fuel and steam increases, and the operating cost for driving becomes enormous.

By the way, according to Japanese Patent Publication No. 40-22743, when a nickel-based catalyst is used, the nickel content and the alkali metal content such as potassium of the co-catalyst are determined on the upstream and downstream sides of the catalyst layer according to the target reaction. On the other hand, there has been proposed an improved method for reducing carbon deposition by using such a catalyst layer.

However, even in this method, the steam carbon ratio is still high.

 An object of the present invention is to solve the above problems.

The present invention can reduce carbon deposition while having a lower steam-to-carbon ratio than when a nickel-based catalyst is used, and has the same high activity and long life as when a noble metal catalyst is used. The present invention provides an industrial method for steam reforming of hydrocarbons by using a catalyst.

[Means for Solving the Problems] The present invention for solving the above-mentioned problems is directed to a method for reforming hydrocarbons by supplying hydrocarbons and steam to a catalyst layer. An upstream catalyst layer filled with a catalyst in which ruthenium or rhodium is supported on a zirconia carrier at a volume ratio of 0.1 to 0.5, and a nickel-supported catalyst was filled at a ratio of 0.9 to 0.5, based on the volume ratio of all catalysts. A steam reforming method for hydrocarbons, comprising a downstream catalyst layer.

 Hereinafter, the method of the present invention will be described in detail.

In the state where the catalyst is filled in the reactor, in the conventional reactor, as shown in FIG. 2, the entirety of the reactor 1 is filled with the nickel-carrying catalyst 3 ', but in the present invention, the reaction is carried out as shown in FIG. The catalyst layer of the apparatus 1 is divided into two layers, and the upstream catalyst layer is filled with a catalyst (hereinafter, referred to as a ruthenium-supported catalyst) 2 in which ruthenium or rhodium is supported on a zirconia carrier, and the nickel-supported catalyst 3 is loaded in the downstream catalyst layer. It is to be filled. Further, the catalyst 2 loaded with ruthenium or the like is packed so that the volume ratio of the total catalyst is 0.1 to 0.5, particularly 0.2 to 0.33, and the nickel supported catalyst 3 is 0.9 to 0.5, particularly 0.8 to 0.67 in terms of the volume ratio of all catalysts.

The loading amount of the supported catalyst 2 such as ruthenium is 0.1% by volume.
If the amount is less than the above, the carbon deposition cannot be sufficiently suppressed by the operation at a low steam-carbon ratio, and if the loading amount of the supported catalyst 2 such as ruthenium is larger than 0.5 by volume ratio, the effect of suppressing the carbon deposition is reduced. It will not be played any more,
On the contrary, the catalyst cost increases.

Therefore, according to the method of the present invention, carbon deposition can be reduced even when the catalyst is operated at a low steam-to-carbon ratio as a whole, and the operating cost can be reduced by reducing the utility cost of fuel and steam. This is an industrially advantageous method because the cost can be reduced and the catalyst cost can be kept low.

Catalyst The catalyst used in the present invention is a combination of (A) a supported catalyst such as ruthenium and (B) a nickel supported catalyst.

(A) Ruthenium-supported catalyst (A) Ruthenium-supported catalyst is prepared by impregnating or mixing a ruthenium compound or a rhodium compound into a zirconia carrier and calcining the metal component so that the content of the metal component is 0.1 to 5% by weight based on the carrier. Those supported in a ratio and molded into an arbitrary shape are suitably used.

Ruthenium sources for supporting ruthenium include ruthenium iodide, ruthenium halides such as ruthenium chloride, ruthenium halides such as ammonium ruthenate, ruthenium halides such as ruthenic chloride, ruthenium hydroxide, ruthenium hydroxide, and dioxide. ruthenium,
Examples thereof include ruthenium oxides such as ruthenium tetroxide, ruthenates such as potassium ruthenate, and organic ruthenium compounds such as ruthenium carbonyl. Preferred is ruthenium halide.

Such a ruthenium source can be used alone or in combination of two or more.

 Particularly preferred is ruthenium trichloride.

Rhodium sources for supporting the rhodium metal include rhodium halides such as rhodium chloride, rhodium halides such as sodium rhodate and ammonium rhodate, rhodium acids such as rhodium chloride, and water. Organic rhodium compounds such as rhodium (III) oxide, rhodium (IV) hydroxide, rhodium nitrate, rhodium oxide and rhodium carbonyl can be mentioned.
Preferred is rhodium halide.

Such a rhodium source may be used alone or in combination of two or more.

 Particularly preferred is rhodium trichloride.

Further, zirconium oxide is usually used as the carrier. A commercially available product can be used as the zirconium oxide.

However, in the present invention, a substance which can be converted to zirconium oxide during catalyst preparation or steam reforming reaction, such as zirconium hydroxide or zirconium nitrate, can be used as a carrier in some cases.

Also, partially stabilized zirconia can be used as the carrier.

This partially stabilized zirconia carrier has particularly high reactivity with water of zirconia itself, improves the steam reforming ability of hydrocarbons, and suppresses carbon deposition generated on the catalyst. In addition to the properties described above, the unique properties of partially stabilized zirconia caused by the addition of a stabilizer, that is, excellent in heat resistance and mechanical strength, for example, there is little decrease in surface area even at a high temperature of 500 ° C. or more, and stable. Can be used for

Such a partially stabilized zirconia carrier can be obtained by modifying and stabilizing a zirconia component by adding a stabilizer.

Examples of the stabilizer used as a component of the partially stabilized zirconia carrier include, for example, an yttrium oxide component, a magnesium oxide component, a cerium oxide component, or a so-called stabilized zirconia stabilizer known in various material fields. Examples include various known oxide components used.

Among these, the yttrium oxide component, the magnesium oxide component, and the cerium oxide component can be particularly preferably used.

The ruthenium-supported catalyst may contain silica, alumina, zeolite, or the like, in addition to zirconia, as long as the object of the present invention is not impaired.

The method of preparing the supported catalyst such as ruthenium is not particularly limited.For example, an impregnation method, an immersion method, a dry mixing method, a wet mixing method, a spray method, and a combination thereof may be appropriately adopted. It is also possible to employ a stationary method, a stirring method, a solution flowing method, a solvent reflux method, or the like as an operation method for carrying.

There is no particular limitation on the shape of the noble metal-supported catalyst thus obtained, for example, fine powder, beads,
Any shape such as a pellet shape, a plate shape, a film shape, and a monolith shape can be adopted.

(B) Nickel-Supported Catalyst As the nickel-supported catalyst, a commonly used catalyst in which nickel is supported on a carrier such as alumina, silica, silica-alumina, or zeolite in an amount of 7 to 20% by weight can be used. .

Hydrocarbon steam reforming reaction The hydrocarbon steam reforming reaction is carried out by filling the above-mentioned catalyst such as ruthenium or the like supported on the upstream side of the reactor and the nickel-supported catalyst on the downstream side of the catalyst layer. And water vapor are supplied.

The hydrocarbon is not particularly limited, and may be, for example, a linear or branched saturated aliphatic hydrocarbon such as methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, and decane, cyclobutane, and cyclobutane. Examples thereof include alicyclic saturated hydrocarbons such as pentane, cyclohexane, methylcyclohexane, and cyclooctane.

Further, the hydrocarbon may be one kind alone or a mixture of two or more kinds of the above various kinds, and may be various refined petroleum fractions.

In the present invention, naphtha or the like is preferable as the hydrocarbon.

The steam to be reacted with the hydrocarbon is not particularly limited.

It is presumed that the hydrocarbon reacts with water vapor according to the following reaction formula.

_{CO + H 2 OCO 2 + H} 2 ( _{exothermic) (II) CH 4 + H} 2 OCO + 3H 2 ( endothermic) (III) (In the formula (I), n denotes one or more real, m represents 2 or more real Therefore, theoretically, the amounts of use of hydrocarbons and steam can be determined by stoichiometric amounts according to the above-mentioned reaction formulas (I) to (III). By loading the supported catalyst and the nickel-supported catalyst in the downstream catalyst layer, the steam-carbon ratio is 1.0 to 3.0,
Preferably it can be as low as 1.5-2.5.

By employing such a steam / carbon ratio, a hydrogen-rich gas can be obtained efficiently and stably.

In this case, the reaction temperature is usually from 300 to 950 ° C, preferably from 400 to 850 ° C. The reaction pressure is usually 0 to 50
kg / cm ² · G, preferably 0~20kg / cm ² · G.

As the reaction system, any system such as a continuous flow system and a batch system may be used. A continuous flow system is preferred. When a continuous flow method is adopted as the reaction method, the gas hourly space velocity (GHSV) of the mixed gas of hydrocarbon and water vapor is usually 10,0
Continuous operation is possible even at a high gas space velocity such as 00 to 15,000 h ^-1 . As the reaction apparatus, a fixed bed tower reactor or a tube reactor is preferable, but a moving bed type or a fluidized bed type reactor that can be separated into an upstream catalyst layer and a downstream catalyst layer is used. Can also.

In this way, when hydrocarbons and steam are reacted in the presence of a catalyst comprising a ruthenium-supported catalyst in the upstream catalyst layer and a nickel-supported catalyst layer in the downstream catalyst layer, the reaction is mainly carried out by the highly active ruthenium-supported catalyst. The reaction proceeds in accordance with the formula (I), and the equilibrium reaction (II) in which the produced carbon monoxide and water are converted into carbon dioxide and hydrogen, and the by-produced methane and water are converted into carbon monoxide and hydrogen. And the equilibrium reaction (III) and the like are simultaneously induced.

Therefore, as a result, a mixed gas of mainly hydrogen and carbon monoxide, and a small proportion of carbon dioxide and methane is obtained. In particular, a hydrogen-rich gas can be obtained by appropriately determining the reaction components stoichiometrically.

The obtained mixed gas can be used for various applications as it is, or can be separated into each gas component and provided for each application.

[Examples] (Examples 1 to 6, Comparative Examples 1 and 2) A flow-type catalytic activity tester was used as a reactor, and light naphtha (initial boiling point 28.5 ° C, end point 104 ° C,
An average molecular weight of 79) was used.

As the upstream catalyst layer filled in the reactor, ruthenium trichloride was kneaded with zirconia and impregnated, then 500
It was used at a ruthenium content of 0.5% by weight. For the rhodium-supported catalyst, rhodium trichloride was similarly supported, and the rhodium content was 0.5.
What was used for weight% was used. As the nickel-supported catalyst of the downstream catalyst layer, one supported on alumina so that the nickel content was 12% by weight was used.

These catalysts were used in the proportions shown in Table 1. In each case, the total amount of the catalyst was 20 ml. The reforming reaction was performed by supplying light naphtha and steam to the catalyst layer under the conditions of a reaction temperature of 800 ° C., a pressure of 0.3 kg / cm ² · G, and an LHSV of 2.8 h ⁻¹ .

In order to try carbon deposition by steam carbon ratio, lower the steam carbon ratio from 5.5 to 1.5, and set the steam carbon ratio that became inoperable due to coking as the operation allowable limit value, and the operation allowable limit in each example The values are shown in Table 1.

As Comparative Example 1, the entire catalyst layer was a nickel-supported catalyst,
Also, as Comparative Example 2, a case where a reforming reaction was performed using the entire catalyst layer as a ruthenium-supported catalyst is also shown.

In Examples 1 to 6, Ru / ZrO ₂ and Rh / ZrO ₂ were used as upstream catalysts.
10-50% by volume, a case of using the 50 to 90 volume% of the Ni / Al ₂ O ₃ as a downstream side catalyst, the steam-carbon ratio of the operation allowable limit can be 1.5 to 2.5, in which On the other hand, in Comparative Example 1, since Ni / Al ₂ O ₃ was used, the steam carbon ratio was 3.0.

(Example 7) The tester used in Example 1 was used as a reactor,
Regarding the steam reforming reaction of light naphtha as a raw material, a catalyst in which the upstream catalyst layer used in Example 2 was Ru / ZrO ₂ and the downstream catalyst layer was Ni / Al ₂ O ₃ (volume ratio 1: 2) , And the life of the catalyst was tested.

The reaction conditions are temperature 800 ° C, pressure 0.3kg / cm ² · G, LHSV2.8h
^-1 , the steam carbon ratio is 2.

FIG. 3 shows the naphtha conversion with respect to the reaction time. Curve 1 shows Ru / ZrO ₂ —Ni / Al ₂ O ₃ of Example 2, curve 2 shows Ni / Al ₂ O ₃ of Comparative Example 1, and curve 3 Represents Ru / ZrO ₂ of Comparative Example 2.

From Figure 3, without naphtha conversion decreases in long-term operation than _{Ru / ZrO 2 -Ni / Al 2} O 3 is Ni / Al ₂ O ₃ of Comparative Example 1 of the present invention, the carbon deposition is large It can be seen that the width is small, and that the naphtha conversion in the case of the total amount of Ru / ZrO ₂ of Comparative Example 2 is almost the same.

[Effect of the Invention] The hydrocarbon steam reforming method of the present invention can be operated at a low steam-carbon ratio, so that the utility cost when performing the reforming reaction can be reduced. Further, the life of the catalyst can be extended, the frequency of replacing the catalyst can be reduced, and the operation rate can be improved. Further, the catalyst cost can be significantly lower than the conventional method using a noble metal catalyst layer.

[Brief description of the drawings]

FIG. 1 shows a state in which a catalyst in which ruthenium or rhodium is supported on a zirconia carrier and a nickel-supported catalyst are packed in the reactor of the present invention, and FIG. 2 shows a state in which a conventional nickel-supported catalyst is packed. FIG. 3 shows the results of a catalyst life test. 1 ... reaction device, 2 ... supported catalyst such as ruthenium,
3. Nickel supported catalyst.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukio Matsushita 1280 Kamiizumi, Sodegaura-cho, Kimitsu-gun, Chiba Pref. Idemitsu Kosan Co., Ltd. -12297 (JP, B1) JP 466482 (JP, B1) JP 44-14703 (JP, B1)

Claims (1)

(57) [Claims] 1. A hydrocarbon steam reforming method for reforming hydrocarbons by supplying hydrocarbons and steam to a catalyst layer,
The catalyst layer, an upstream catalyst layer filled with a catalyst in which ruthenium or rhodium is supported on a zirconia support at a ratio of 0.1 to 0.5 in terms of a volume ratio of the entire catalyst, and a nickel-supported catalyst having a volume ratio of 0.9 to 0.5 in a total catalyst volume ratio of 0.9 to 0.5. 1. A method for steam reforming of hydrocarbons, comprising: a downstream catalyst layer filled in a proportion.