JP3534451B2 - Catalyst for high calorie gas production - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a catalyst used for steam reforming a hydrocarbon to produce a high-calorie alternative natural gas (hereinafter, also referred to as SNG).

[0002]

As a catalyst for steam reforming of hydrocarbons,
A nickel-based catalyst in which nickel is supported on alumina or the like is known. However, nickel-based catalysts have a drawback that carbon precipitation easily occurs on the catalyst, which causes a decrease in activity. Therefore, the ratio of the number of moles of steam during the reforming reaction to the number of carbons in the raw material hydrocarbon ( Hereinafter, it is necessary to increase the S / C ratio). Therefore, generally, in the steam reforming of naphtha using a nickel-based catalyst, the S / C ratio is operated at around 3 to 5.

On the other hand, the ruthenium-based catalyst has an action of suppressing carbon deposition, so that it can be operated at an S / C ratio which is about half that of the conventional nickel-based catalyst. Therefore,
In SNG production, the steam basic unit (the amount of steam used per product unit amount) accounts for a large percentage of the operating cost of the SNG manufacturing process, so the economic effect of reducing the manufacturing cost is expected by using a ruthenium catalyst. it can. Examples of such ruthenium-based catalysts include ruthenium supported on an alumina or silica carrier (JP-A-57-4232), ruthenium supported on high-purity alumina (JP-A-4-59048),
What uses a carrier obtained by adding cerium oxide to an alkali metal oxide or an alkaline earth metal oxide (JP-A-4-4-2).
No. 65156), using an alkali salt such as sodium ruthenate as a precursor (JP-A-60-227834).
Which uses a zirconium carrier (Japanese Patent Laid-Open No. Hei 2)
No. 302304), supported on a stabilized or partially stabilized zirconia carrier (JP-A-2-286787).
No. gazette) has been reported.

However, ruthenium-based catalysts are easily poisoned by sulfur components such as hydrogen sulfide (catalyst 35).
Vol. 224 (1993)) and the fact that inactive carbon deposits on the catalyst when the catalyst is poisoned by sulfur content (eg Int. Ga.
s Research Conference, Proceedings,
4, p. 124 (1989), catalyst 35, p. 224 (1993)). Thus, even if the ruthenium catalyst has a carbon deposition suppressing effect, if it is poisoned by sulfur components such as hydrogen sulfide contained in the raw material gas,
The advantage of the ruthenium catalyst is not taken advantage of, which is a big problem in industrialization.

In the conventional high temperature steam reforming catalyst for producing hydrogen, thermal carbon deposition occurs due to causes other than poisoning by hydrogen sulfide, and therefore, a high degree of catalyst design regarding sulfur resistance including countermeasures for carbon deposition is provided. Was not needed. However, in SNG production by low-temperature steam reforming of hydrocarbons, the catalyst is required to exhibit equilibrium conversion at a reaction temperature of about 400 to 500 ° C. in terms of chemical equilibrium. This temperature is about half that of ordinary steam reforming, and carbon deposition is extremely likely to occur even in equilibrium. Furthermore, since the catalysts are apt to be poisoned by impurities originally present in the raw materials and sulfur compounds such as odorants added to the raw materials and catalyst deterioration easily occurs, it is extremely difficult to use the catalyst in the conventional method as it is. difficult. A catalyst that overcomes the above problems cannot be produced simply by adding a third component, diversifying the types of starting materials, and synthesizing a carrier, and adding a third component that makes the carrier sulfur-resistant. A denser catalyst, in which the physical properties of the carrier and the dispersibility of the active metal are controlled, is awaited, but so far, such a densely designed ruthenium-based catalyst is
I can hardly find it.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a catalyst in which the catalytic activity is not significantly reduced even when carbon is deposited, and the activity is not reduced even if a sulfur content in the raw material remains to some extent, In other words, it has carbon resistance and sulfur resistance,
It is intended to provide a catalyst for producing a high-calorie gas by a low-temperature steam reforming method of hydrocarbons.

[0007]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, (1) In addition to the influence of the carrier, the aggregated state and dispersibility of the active metal to be supported are It plays an extremely important role in reaction activity and reaction selectivity. (2) A complex of Group IIa metal oxide, Group IIIa metal oxide or lanthanoid metal oxide with alumina is used.
The catalyst obtained by supporting ruthenium on the carrier obtained by calcining at a low temperature of 00 ° C or lower does not only show equilibrium conversion in the SNG production process in the low temperature range, but also contains sulfur compounds such as hydrogen sulfide in the source gas. It was found that even if it is present, it is difficult to be poisoned and carbon precipitation is suppressed, and the present invention has been completed.

That is, according to the present invention, ruthenium is supported on an activated alumina composite carrier containing an oxide of a IIa group, a IIIa group and / or a lanthanoid metal, which is insoluble and fixed as a ruthenium hydroxide using an alkaline aqueous solution. Turned into
Then, this is washed and dried, and then reduced to obtain 350.
Performs steam reforming of hydrocarbons at low temperatures of ~ 500 ° C
The present invention provides a catalyst for producing regas .

[0009]

The catalyst for producing high-calorie gas of the present invention is obtained by supporting ruthenium on an activated alumina composite carrier, insolubilizing it as ruthenium hydroxide using an aqueous alkali solution, washing and drying it, and then reducing it. Among them, it is a composite containing 5 to 30% by weight of IIa metal oxide, IIIa group metal oxide and / or lanthanoid metal oxide, and has a specific surface area of 60 m ² / g or more, Also, 0.5 to 5% by weight of ruthenium was loaded on a carrier having a pore volume of 0.2 to 0.5 ml / g, and then reduction treatment was performed to adsorb carbon monoxide (hereinafter sometimes referred to as CO). It is preferable that the amount is 2 ml / g or more.

In the catalyst of the present invention, as the Group IIa metal oxide, oxides of beryllium, magnesium, calcium, strontium, barium and radium can be used, but oxides of magnesium and barium are particularly preferable.

As the group IIIa metal oxide, oxides of scandium, yttrium and the like can be used, but yttrium oxide is particularly preferable.

As the lanthanoid metal oxide, oxides of lanthanum, cerium, praseodymium, neodymium, promethium, samarium and the like can be used, but lanthanum and cerium oxides are particularly preferable.

For the group IIa metal oxide, the group IIIa metal oxide and the lanthanoid metal oxide, chlorides, nitrates and the like can be used as precursors in addition to the oxides.

As the alumina, an alkoxide such as aluminum isopropoxide can be used as a precursor.

Group IIa metal oxides in composite supports, III
The amount of group a metal oxide and lanthanoid metal oxide is 5 to
The amount is preferably 30% by weight, preferably 10 to 30% by weight, more preferably 15 to 25% by weight. If this amount is less than 5% by weight, a sufficient effect cannot be obtained with respect to sulfur resistance, and therefore a sufficient life extension of the catalyst cannot be expected. That is, since sulfur compounds such as hydrogen sulfide in the raw material gas are adsorbed and absorbed by the group IIa metal oxides, the group IIIa metal oxides and the lanthanoid metal oxides, ruthenium, which is an active component, is less likely to be poisoned, and the service life becomes longer. Will be extended. If the amount of IIa group metal oxides exceeds 30% by weight,
This is not preferable because the amount of alumina decreases relatively. That is, alumina is effective for improving the specific surface area and mechanical strength, and therefore, if the amount of alumina is extremely small, these improving effects cannot be expected.

The specific surface area of the composite carrier is 60 m ² / g or more,
Preferably 60-150 m ² / g, more preferably 60-
90 m ² / g, the pore volume is 0.2-0.5 ml / g, preferably 0.3-0.4 ml / g is good, and when the specific surface area of the carrier or the pore volume is smaller than this, The dispersibility of ruthenium to be used is deteriorated and the activity during SNG production is impaired. Further, in such a case, the carrier component is not sufficiently exposed on the surface, so that not only the effect of sulfur resistance is lowered but also a predetermined amount of the active component cannot be supported. On the contrary, when the specific surface area is extremely increased, the dispersibility effect and the sulfur resistance effect are improved, but there is a problem that sufficient carrier strength cannot be obtained.

In the composite carrier, the metal oxide is dispersed in a solvent such as water, methanol, ethanol, acetone or the like and kneaded, followed by firing, or by adjusting the pH of a mixed solution of the chloride and nitrate of the metal, It can be prepared by firing the coprecipitate. Alternatively, oxides may be simply mechanically mixed and fired. The order of mixing alumina and the metal oxide is not particularly limited. For example, a mixture of an aluminum compound and one of the group IIa metal oxides may be further mixed with a group IIIa metal oxide and / or a lanthanoid metal oxide.

As a method for supporting ruthenium on the above composite carrier, a known method such as an impregnation method can be used. As the active ingredient ruthenium, precursors such as ruthenium trichloride anhydride, ruthenium trichloride hydrate and ruthenium nitrate can be used, but ruthenium trichloride monohydrate is particularly preferable from the viewpoint of solubility.

The amount of ruthenium supported is 0.5 to 5% by weight,
It is preferably 0.5 to 3% by weight. If the supported amount is less than this, the amount of active sites will be small, and if it is greater than this, the activity will not be improved and the dispersibility will be decreased, which is not preferable.

As a preliminary preparation for supporting ruthenium on the carrier, first, the carrier is weighed, and water is gradually added dropwise to the carrier so that water is sufficiently absorbed inside the carrier. This water absorption is preferably performed until it is saturated inside the carrier. In this way, the saturated water absorption amount is obtained in advance. Here, a solution in which a predetermined amount of ruthenium trichloride monohydrate is dissolved is absorbed by the carrier in an amount equal to the saturated water absorption. Then 10-15
An excess amount of volume% ammonia water is added dropwise to the ruthenium concentration, and the chloride is converted to hydroxide as in the formula RuCl ₃ + 3NH ₄ OH → Ru (OH) ₃ + NH ₄ Cl (1) to insolubilize / immobilize. .

At this time, since the chlorine anion becomes water-soluble ammonium chloride as shown in the formula (1), dechlorination can be performed in the washing process. The ruthenium-immobilized carrier is dried at 200 ° C. or lower, preferably 150 ° C. or lower, more preferably 100 ° C. or lower under reduced pressure or atmospheric pressure. If this temperature is too high, some of the hydroxide will change to oxide. In order to reduce the carrier mixed with oxides, a temperature of 200 ° C. or higher is required, so that the dispersibility of ruthenium after the reduction treatment becomes worse due to the higher reduction temperature. From this point as well, it is preferable to avoid the presence of oxides during drying. Further, if the drying temperature is too low, the drying time becomes extremely long, which is not preferable.

In addition to ammonia water, an aqueous solution of a base such as sodium hydrogen carbonate, sodium carbonate, caustic soda, and caustic potash can be used for immobilization. However, in the case of sodium salts and potassium salts, there is a risk that alkali metal cations will remain during cleaning, so ammonia water is the easiest to handle.

The reduction of the supported ruthenium catalyst is carried out in order to improve the dispersibility of the supported metal so that the metal does not aggregate.
The temperature is preferably 80 to 180 ° C, preferably 100 to 180 ° C, more preferably 100 to 150 ° C. Pure hydrogen, hydrogen / steam, and carbon monoxide can be used as the reducing gas. Among these, it is preferable to use hydrogen gas or hydrogen / steam gas, and it is particularly preferable to use hydrogen gas.

Since the catalyst thus obtained has excellent sulfur resistance, sulfur compounds such as hydrogen sulfide may be mixed in the raw material to some extent, and further the carbon resistance is excellent. The C ratio can be lowered as compared with the conventional one, that is, a high calorie gas can be produced with a smaller amount of water vapor than the conventional one.

When the high calorie gas is produced using the catalyst of the present invention, the hydrocarbon as the main component of the raw material has 2 to 16 carbon atoms, preferably 2 to 10 carbon atoms, particularly 3 to 8 carbon atoms. Is preferred, and the reaction temperature is 350-500.
℃, preferably 400-450 ℃, pressure is 20kg / cm ² G
The following is preferably atmospheric pressure to 15 kg / cm ² G, particularly preferably 8 to 10 kg / cm ² G, and GHSV of 600 to 1200.
h ^-1 is preferred.

[0027]

EXAMPLES Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to these.

In the following examples, for the analysis of the product, a SUS pipe (inner diameter 3 mmφ × 2 m) having 60-80 mesh Unibeads-C (manufactured by GL Science Co.,
It was carried out by a gas chromatograph (GC) equipped with a thermal conductivity type detector (TCD) equipped with a separation column filled with (styrene-divinylbenzene copolymer). The specific surface area and pore volume of the carrier were measured by a surface area measuring device (manufactured by Bell Co.), and the carbon monoxide adsorption amount was measured by an automatic adsorption device (manufactured by Okura Riken Co., Ltd.). As for the amount of absorbed hydrogen sulfide, a TCD-GC equipped with a Golay column was used, and a fixed amount of hydrogen sulfide pulse was used.
It was determined from the amount of unabsorbed hydrogen sulfide by the pulse method of flowing the catalyst at 0 ° C.

Example 1 19.8 g of powder of cerium oxide (CeO ₂ manufactured by Wako Pure Chemical Industries, Ltd.)
After 82.2 g of activated alumina powder (Al ₂ O ₃ aluminum oxide 90 type I, manufactured by Merck & Co., Inc.) was thoroughly mixed in a mortar, about 40 ml of water was added and further kneaded. 2.7 kP of the pasty mixture on a rotary evaporator
Under an a (about 20 mmHg) vacuum, it was heated to 60 to 70 ° C. with an infrared hot plate to remove water. 105 this
After pre-drying with a constant temperature dryer kept at ℃, it was baked at 500 ℃ for 3 hours using an electric furnace to obtain a composite carrier. The specific surface area at this time is 82.5 m ² / g, and the pore volume is 0.4 ml / g.
Met. Ruthenium trichloride monohydrate (RuCl ₃ · H ₂
2 g of the above composite carrier powder was immersed in an aqueous solution prepared by dissolving 1 g of O 2 (manufactured by Kanto Kagaku Co., Ltd.) in 37 ml of water for 1 hour to remove the residual liquid, and then about 2.7 kPa was applied using a rotary evaporator. Water was removed by heating to 40 to 45 ° C. on an infrared hot plate under vacuum. This is 10
Add to 15% by volume ammonia water and keep at 40 ° C.
After stirring for 2 hours and insolubilizing and fixing as shown in formula (1), the catalyst was separated using a Buchner funnel and thoroughly washed with pure water. Further, this was dried in a vacuum dryer at 40 to 45 ° C. for 8 hours to give ruthenium 1.8% by weight and cerium oxide 2
A catalyst was prepared consisting of 1.6 wt% balance alumina.
This was sized to 8-12 mesh.

10 ml of the above-obtained catalyst was mixed with S having an inner diameter of 16 mmφ.
It was filled in a US-made cylindrical reaction tube and subjected to hydrogen reduction for 8 hours at a pressure of 8 kg / cm ² G, a reduction temperature of 150 ° C., and a GHSV of 3000 h ⁻¹ . The amount of CO adsorbed on the catalyst after the reduction treatment is about 3.9 ml /
g: Standard state (hereinafter referred to as (STP)). Then, butane gas (mixed gas of n-butane and iso-butane (n / iso = about 1.8), containing 10 ppm of hydrogen sulfide) was introduced together with steam into the reactor containing the supported ruthenium catalyst. The operating conditions were a reaction pressure of 8 kg / cm ² G, a reaction temperature of 450 ° C., GHSV of 600 h ⁻¹ , and S / C of 1. The results at this time are shown in Table 1.

Example 2 Yttrium oxide (Y ₂ O ₃ manufactured by Kanto Chemical Co., Inc.) powder 21.
1 g and 78.5 g of activated alumina powder were used in the same manner as in Example 1 to give a specific surface area of 81.1 m ² / g and a pore volume of 0.4.
A carrier of ml / g was prepared, and a catalyst composed of 2.1% by weight of ruthenium, 22.1% by weight of yttrium oxide and the balance alumina was prepared. The results of using this catalyst for the reaction of butane and steam after reduction are shown in Table 1. The amount of CO adsorbed after reducing the catalyst was about 3.9 ml / g (STP).

Example 3 Lanthanum oxide (La ₂ O ₃ Wako Pure Chemical Industries, Ltd.) powder 20.5
g and 79.6 g of activated alumina powder in the same manner as in Example 1 with a specific surface area of 80.5 m ² / g and a pore volume of 0.3 ml.
/ G of the carrier was prepared to prepare a catalyst composed of 2.0% by weight of ruthenium, 21.1% by weight of lanthanum oxide and the balance alumina. The results of using this catalyst for the reaction of butane and steam after reduction are shown in Table 1. The amount of CO adsorbed after reducing the catalyst was about 2.5 ml / g (STP).

Example 4 Magnesium oxide (MgO manufactured by Wako Pure Chemical Industries, Ltd.) powder 20.
Using 3 g and 80.2 g of activated alumina powder, the specific surface area was 62.5 m ² / g and the pore volume was 0.3 in the same manner as in Example 1.
A carrier of ml / g was prepared, and a catalyst composed of 2.1% by weight of ruthenium, 20.5% by weight of magnesium oxide and the balance alumina was prepared. The results of using this catalyst for the reaction of butane and steam after reduction are shown in Table 1. The amount of CO adsorbed after reducing the catalyst was about 2.4 ml / g (STP).

Example 5 Barium oxide (BaO Wako Pure Chemical Industries, Ltd.) powder 20.7 g
And 81.3 g of activated alumina powder were used in the same manner as in Example 1 to give a specific surface area of 60.2 m ² / g and a pore volume of 0.3 ml /
g of the carrier was prepared to prepare a catalyst composed of 2.1% by weight of ruthenium, 21.5% by weight of barium oxide and the balance alumina. The results of using this catalyst for the reaction of butane and steam after reduction are shown in Table 1. The amount of CO adsorbed after the above catalyst was reduced was about 2.1 ml / g (STP).

Comparative Example 1 Activated alumina (specific surface area 250 m ² / g, pore volume 0.5)
A catalyst comprising 2.2% by weight of ruthenium and the balance alumina was prepared in the same manner as in Example 1 except that only the powder (ml / g) was used as the carrier. The results of using this catalyst for the reaction of butane and steam after reduction are shown in Table 1. The amount of CO adsorbed after the reduction of the catalyst was about 3.7 ml / g (ST
P).

In Examples 1 to 5 and Comparative Example 1, Table 1
The conversion rate and the selectivity shown in the table are calculated by the following formula (2).
And calculated by the formula (3).

[0037]

[Equation 1]

[0038]

[Table 1]

As is clear from Table 1, when the source gas contains a sulfur compound such as hydrogen sulfide, the catalyst containing no Group IIa metal oxide, Group IIIa metal oxide or lanthanoid metal oxide in the carrier is used. In addition to the poisoning of the catalyst caused by the sulfur content, the conversion rate decreases, and as a secondary effect of the poisoning, carbon deposition on the catalyst becomes remarkable and the selectivity also decreases. That is, it can be seen that the catalyst life not including the third component is shortened by the sulfur content. It can be seen that the catalyst of the present invention shows stable performance for a long period of time without being poisoned even if the raw material gas contains a sulfur compound such as hydrogen sulfide.

Reference Example 1 Regarding the catalyst prepared by using the carrier prepared in Example 1 and supporting 0.5 to 5% by weight of ruthenium, CO18.
A high-purity gas consisting of 5% by volume and the remaining helium was adsorbed at room temperature to determine the CO adsorption amount. CO is generally a metal (0
It is easy to adsorb to a reduced metal species having a high valency) or a high degree of coordination unsaturation, and a large adsorption amount can be interpreted as a high dispersibility of a metal in a low oxidation state. Further, a high-purity gas consisting of 4.7% by volume of hydrogen sulfide and the remaining helium was brought into contact with the catalyst at 400 ° C. by a pulse method to determine the amount of absorption. The relationship between the CO adsorption amount and the hydrogen sulfide absorption amount is shown in FIG.

Reference Example 2 A catalyst prepared by using the carrier prepared in Example 4 and supporting 0.5 to 5 wt% of ruthenium on the carrier was used.
The CO adsorption amount and hydrogen sulfide absorption amount were measured in the same manner as in. The result is shown in FIG.

COMPARATIVE EXAMPLE 2 Using the activated alumina carrier of Comparative Example 1 and supporting 0.5 to 5% by weight of ruthenium on the catalyst, Reference Example 1
The CO adsorption amount and hydrogen sulfide absorption amount were measured in the same manner as in. The result is shown in FIG.

Results From FIG. 1, it is seen that the catalysts having a high ruthenium dispersibility tend to have a high hydrogen sulfide absorption amount. This means that if ruthenium is highly dispersed, the amount of active sites will increase accordingly, and as a result, the amount of sulfur resistance will increase. In other words, the life extension effect is manifested accordingly. A catalyst prepared by adding a Group IIa metal oxide, a Group IIIa metal oxide, and a lanthanoid metal oxide to an alumina carrier has a hydrogen sulfide absorption amount of about 5% even if the catalyst has the same dispersibility as those containing no third component. It increased by 2 to 2.5 times. This means that hydrogen sulfide is absorbed on the side of the composite carrier other than ruthenium. That is, the life extension effect was observed even in the presence of hydrogen sulfide in all of Examples 1 to 5 because hydrogen sulfide was absorbed on the carrier side and poisoning of ruthenium, which is an active site, was suppressed. is there. Therefore, in order to improve the absorption capacity of hydrogen sulfide and the like on the carrier side and to retain highly dispersed ruthenium, 6
A specific surface area of 0 m ² / g or more is required, and it is indispensable to have a CO adsorption amount of 2 ml / g (STP) or more as an index of dispersibility of ruthenium.

[0044]

When the catalyst of the present invention is used, when a natural gas substitute (SNG) for high-calorie gas from hydrocarbons is obtained, sulfur compounds such as hydrogen sulfide are mixed in the raw material as impurities or odorants. However, since the catalyst is not poisoned and carbon deposition is suppressed, the catalyst life is long, and a high calorific gas can be produced with a high conversion and a high selectivity.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between dispersibility (CO adsorption amount) of supported ruthenium and hydrogen sulfide absorption amount.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Yoshi ▼ Takashi Sawa 1-69-25 Iwana, Noda City, Chiba (56) Reference JP-A-4-281845 (JP, A) JP-A-61-138535 (JP, A) JP 62-156196 (JP, A) JP 2-75343 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01J 21/00 -38 / 74

Claims (4)

(57) [Claims] 1. A ruthenium is supported on an activated alumina composite carrier containing an oxide of a IIa group, a IIIa group and / or a lanthanoid metal, which is insoluble and fixed as a ruthenium hydroxide using an alkaline aqueous solution, which is then fixed. Charcoal at low temperature of 350-500 ℃
Steam reforming of hydrogen fluoride to produce high calorie gas
Because of the catalyst. Wherein the alkali aqueous solution, catalysts according to claim 1, wherein the aqueous ammonia. 3. A reduction treatment temperature, according to claim 1 or 2 wherein the catalytic is 80 to 180 ° C.. 4. A genus IIa, genus IIIa and / or lanthanoid gold
Activated alumina composite containing 5 to 30% by weight of oxides of the genus
A body with a specific surface area of 60 m²/ G or more and pore volume
Ruthenium is added to a carrier whose product is 0.2 to 0.5 ml / g.
0.5 to 5% by weight is supported, and then reduction treatment is performed.Obtained
Is something thatThe method according to any one of claims 1 to 3.Touch
Medium.