JPH0747273A - Catalyst for reforming hydrocarbon fuel and reforming device - Google Patents

Abstract

PURPOSE:To obtain a catalyst used for reforming a fuel consisting mainly of aliphatic hydrocarbons into a fuel gas composed mainly of hydrogen, which is durable and manufactured at low cost, and to provide a reforming device which uses the reforming catalyst effectively. CONSTITUTION:This reforming catalyst is used for reforming a fuel consisting mainly of aliphatic hydrocarbons into a fuel gas composed mainly of hydrogen. Ru4 is mainly carried in catalytic particles 1, and Ni2 entirely covers each catalytic particle. In addition, the reforming device reforms the fuel consisting mainly of the aliphatic hydrocarbons into the fuel gas composed mainly of hydrogen. The reforming device is filled with the reforming catalyst from the inlet of a reforming pipe to a position where the internal temperature of the reforming pipe can somewhat hardly cause the poisoning of the catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrocarbon reforming catalyst having improved durability, and a reformer effectively utilizing this reforming catalyst.

[0002]

2. Description of the Related Art In the conventional method for reforming hydrocarbons, particularly steam reforming method, a catalyst in which nickel is supported on a refractory carrier such as alumina or magnesia is used. Carbon deposition occurs depending on the type of hydrocarbon used as a raw material, and therefore, in order to prevent this, a catalyst to which an alkali metal such as K2 O is added as a trace component in addition to nickel is used. However, even with this catalyst, there are cases where it is not possible to prevent carbon deposition or the like due to the type of hydrocarbon or operating conditions. In that case, a catalyst in which ruthenium is supported on a similar refractory carrier is used. .

On the other hand, in the conventional general steam reforming method for hydrocarbons, these catalysts are filled in the reforming pipe, and the steam reforming reaction is an endothermic reaction. While reforming the catalyst-filled bed by supplying a gas in which hydrocarbon and steam are mixed at an appropriate ratio. For large-capacity reforming, multiple reforming tubes are used. Normal reforming reaction conditions are atmospheric pressure to 30
Pressure of about atmospheric pressure, steam / carbon ratio of 3 or more, about 3
Inlet / outlet temperature of 50-450 ° C / about 700-850 ° C. Incidentally, conventionally, any one of the above catalysts is uniformly filled from the inlet to the outlet of the reforming tube.

[0004]

However, these catalysts have some problems. First, it is easy to be poisoned by the sulfur component contained in the raw material hydrocarbon. These sulfur components are usually removed by a hydrodesulfurization method. For example, when the raw material hydrocarbon is city gas, a sulfur content of about 5 ppm is usually added as an odorant. Depending on the hydrodesulfurization method, 0.05-0.1pp
Although it is desulfurized to about m, the reforming catalyst is still poisoned. In particular, the catalyst at the inlet, which has a low temperature, is easily poisoned.

Since the Ru catalyst is expensive, the Ni catalyst is usually supported in a large amount of 5 to 30% by weight, whereas the Ru catalyst is supported in a small amount of about 0.1 to 2% by weight, and Since Ru is dispersed and carried on the surface of the catalyst, it becomes more susceptible to sulfur poisoning. As a result, a large problem occurs in the durability of the catalyst, for example, carbon deposition is likely to occur.

On the other hand, the Ni catalyst has a higher sulfur poisoning resistance than the Ru catalyst, but it is still poisoned and its activity decreases. As a result, since the Ni catalyst is originally a catalyst in which carbon is more easily deposited than the Ru catalyst, the durability of the catalyst also suffers from carbon deposition and the like.

Further, the Ni catalyst added with K2O, etc.
It is known that the effect of K2 O is lost over time, and carbon is more likely to precipitate.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in order to obtain a reforming catalyst that is low in cost and durable, a fuel containing an aliphatic hydrocarbon as a main component is hydrogenated. A reforming catalyst used for reforming into a fuel gas containing as a main component, characterized in that Ru is mainly carried on the inner layer of the catalyst particles and Ni is carried on the entire catalyst particles. The present invention provides a reforming catalyst for hydrocarbon fuel.

In the reforming catalyst of the present invention, Ni is supported in an amount of 5 to 30% by weight, and Ru is in the range of 0.1 to 2 based on the weight of the catalyst particles.
Supported by weight%. That is, Ni, which is relatively unlikely to be poisoned by sulfur, mainly constitutes the outer layer portion of the catalyst particles, and Ru, which has high activity, mainly constitutes the inner layer portion of the catalyst particles. As a result, Ru in the inner layer portion is less likely to be poisoned to prevent the activity from lowering. Therefore, it is possible to obtain a reforming catalyst that has low cost and improved durability.

In order to effectively utilize such a reforming catalyst, the present invention is an apparatus for reforming a fuel containing an aliphatic hydrocarbon as a main component into a fuel gas containing hydrogen as a main component,
A reforming device for a hydrocarbon-based fuel, characterized in that the reforming catalyst as described above is filled from the inlet of the reforming pipe to a position where the temperature in the reforming pipe is relatively low so that the catalyst is less likely to be poisoned. It is provided.

The reforming apparatus according to the present invention effectively utilizes the properties of the above-mentioned reforming catalyst of the present invention which is not easily poisoned even at a relatively low temperature and retains its activity, and reduces the cost of the entire reforming apparatus. , A relatively low temperature place, that is, near the inlet of the reforming pipe, is filled with the novel reforming catalyst of the present invention, and a relatively high temperature place, that is, near the outlet of the reforming pipe (the effect of poisoning is relatively In the case of a small amount), a Ni catalyst (which has a low cost) conventionally used is filled. The reason for this is that if the temperature becomes relatively high, the reaction rate will increase and the effect of sulfur poisoning on the reforming rate will decrease. The filling amount of the reforming catalyst according to the present invention is
Approximately 1/5 to 1/2 of the total length (filling length) of the reforming pipe from the inlet of the reforming pipe, depending on the reforming operation temperature and the scale of the reforming pipe.
Up to is appropriate. The standard of the filling amount is that the temperature of the reforming tube is relatively high, that is, about 600 ° C., and the poisoning due to the sulfur content is small.

The reforming catalyst / reforming device of the present invention can be widely applied to reforming methods other than the steam reforming method.

[0013]

Embodiments of the reforming catalyst and the reforming apparatus of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view conceptually showing the structure of the reforming catalyst of the present invention, and FIG. 1 (a) shows that Ru is concentratedly supported on a portion 3 inside the catalyst particle 1. , N
i is supported on the entire catalyst particles 2. Therefore, the portion 2 mainly carries Ni, and the portion 3 mainly carries Ru (in actuality, a state of Ru + Ni).

FIG. 1 (b) shows that the central portion 4 carries Ru and the entire catalyst particles 2 carry Ni. In this case, Ni may be supported only on the outer layer portion, but when the supported amount increases, Ni is also supported on the central portion (therefore, the central portion becomes Ni + Ru).

FIG. 2 is a sectional view conceptually showing the structure of a conventional reforming catalyst. FIG. 2A shows a Ni catalyst, and FIG. 2B shows a Ru catalyst. These conventional reforming catalysts are poisoned by the sulfur content from the outer layer and their activities are reduced.
In particular, in the case of the Ru catalyst, the effect is large because the supported amount is small.

In the case of the reforming catalyst of the present invention, it is gradually poisoned from the outer layer portion, but since Ru in the inside retains sufficient activity without being poisoned, no decrease in activity is observed. this is,
Due to the existence of a diffusion layer as a barrier, the outer layer is more easily poisoned, and Ni has a greater affinity for sulfur than Ru, so Ni is selectively poisoned. it is conceivable that. These effects are different depending on the type of hydrocarbon to be reformed, but are larger as the number of carbons in the constituent hydrocarbons is larger. For example, LNG
LPG is more effective than LPG. This is because LNG has CH4 as a main component, while LPG has C3 H8 and C4 H10 as main components.

The supporting method may be an ordinary impregnation method, but when supporting the inner layer, a method using an organic acid such as citric acid or oxalic acid is preferable. The supported amount of Ru is about 0.1.
Sufficient effect is exhibited at up to 2% by weight. About 5 for Ni
An amount of ~ 30% by weight is sufficient. Even if the amount is large, the degree of dispersion is deteriorated, so that it is not always effective. Further, the supported amount is also limited by the surface area of the carrier, but in the usual case,
15 to 25% by weight is preferable.

Next, a hydrocarbon fuel reforming apparatus using the reforming catalyst of the present invention will be described. Poisoning by sulfur is more remarkable at lower temperatures, and the reaction rate becomes higher at higher temperatures, so the effect of sulfur poisoning on the reforming rate is small. Therefore, generally, as shown in FIG. 3, the reforming catalyst 8 of the present invention is charged from the inlet 7 of the reforming pipe 6 to about 1/5 to 1/2 of the entire reforming pipe, and the remaining It is effective to fill the portion with a commercially available Ni catalyst 9 for steam reforming and perform reforming. However, this fill height depends on the operating temperature of the reformer. In the normal steam reforming reaction, the operation is performed at an inlet temperature of about 400 ° C and an outlet temperature of about 800 ° C, but from the reforming pipe inlet to the place where the reforming pipe temperature reaches about 600 ° C. It is suitable to pack the reforming catalyst according to the invention. That is, at a temperature of about 600 ° C., the influence of sulfur poisoning on the reforming rate is small, and therefore the catalytic activity does not decrease even if the conventional Ni catalyst is used. Therefore,
By configuring the reforming catalyst in this way, the cost of the entire apparatus can be reduced.

Specific examples of the reforming catalyst according to the present invention will be described below. Example 1 About 20% by weight of Ni was supported on a commercially available γ-alumina carrier powder by an impregnation method, particles having an average diameter of 6 mm were granulated, and impregnated with an oxalic acid solution of Ru salt to support 0.5% by weight of Ru. Then, heat treatment was performed to prepare a catalyst. FIG. 4 shows the line analysis result of the cross section of the prepared catalyst particles. As a result, it was found that Ni was almost uniformly supported and Ru was concentratedly supported on a part of the inner layer.

After the catalyst was poisoned with 0.01% by weight of sulfur, CH4 was used as a source gas and s / c was 2.5.
Table 1 shows the results (methane conversion rate) of the activity test carried out at temperatures of 500, 550 and 600 ° C. For comparison, a commercially available Ni catalyst for steam reforming (6 mmφ) was similarly subjected to sulfur poisoning and an activity test was performed (Comparative Example). Table 1 500 ° C 550 ° C 600 ° C No sulfur poisoning 23% 42% 53% Reforming catalyst 1 Sulfur poisoning 20% 40% 52% Without sulfur poisoning 21% 41% 52% Comparative Example 2 With sulfur poisoning 8% 12% 26% Example 2 A commercially available granular γ-alumina carrier (average 3 mmφ) was added with Ru.
Example 1 of a catalyst prepared by loading Ru in an amount of 1% by weight with an oxalic acid solution of a salt, impregnating a solution of Ni in the amount of 20% by weight, and then performing heat treatment
Then, the same treatment as above was performed and an activity test was conducted. Further, in the comparative example, the same treatment was performed using a commercially available Ni catalyst for steam reforming (3 mmφ), and an activity test was conducted. The results are shown in Table 2.

Table 2 500 ° C 550 ° C 600 ° C Without sulfur poisoning 39% 57% 65% Reforming catalyst 2 With sulfur poisoning 36% 53% 60% No sulfur poisoning 36% 55% 61% Comparative Example 2 With sulfur poisoning 12% 19% 33%

[Brief description of drawings]

FIG. 1 is an explanatory view showing a supported state of a catalytically active metal of a reforming catalyst according to the present invention.

FIG. 2 is an explanatory view showing a supported state of a catalytically active metal of a conventionally used reforming catalyst.

FIG. 3 is an explanatory view showing a reformer according to the present invention.

FIG. 4 is an explanatory diagram showing the distribution of catalytic metal elements in the reforming catalyst particles according to the present invention.

[Description of Reference Signs] 1 catalyst particles 2 Ni-supported portion 3 Ru + Ni-supported portion 4 Ru or Ru + Ni-supported portion 5 Ru-supported portion 6 Reforming tube 7 Inlet 8 Reforming catalyst 9 according to the present invention 9 Conventional Ni catalyst

Claims (7)

[Claims] 1. A reforming catalyst used for reforming a fuel containing an aliphatic hydrocarbon as a main component into a fuel gas containing hydrogen as a main component, wherein Ru is supported mainly inside the catalyst particles, and Ni is contained. A hydrocarbon-based fuel reforming catalyst, characterized in that is carried over the entire catalyst particles. 2. The reforming catalyst according to claim 1, wherein the peak of the Ru concentration distribution is present in the central portion of the catalyst particles. 3. The reforming catalyst according to claim 1, wherein the Ru concentration distribution peak is present in an intermediate region between the surface layer and the center of the catalyst particles. 4. The reforming catalyst according to claim 1, wherein 5 to 30% by weight of Ni is supported and 0.1 to 2% by weight of Ru is supported with respect to the weight of the catalyst particles. . 5. An apparatus for reforming a fuel containing an aliphatic hydrocarbon as a main component into a fuel gas containing hydrogen as a main component, wherein the reforming catalyst according to claim 1, 2, 3 or 4. A hydrocarbon-based fuel reforming device, characterized in that the catalyst is filled from a pipe inlet to a position where the temperature of the reforming pipe is relatively low, where the catalyst is less likely to be poisoned. 6. The reforming apparatus according to claim 5, wherein a conventionally used Ni catalyst is filled in the remaining portion in the reforming tube. 7. The reforming catalyst has a reforming tube temperature of about 600 ° C.
The reforming apparatus according to claim 5, wherein the reformer is filled up to the position.