JPS63278552A - Catalyst for producing methane-containing gas - Google Patents

Abstract

PURPOSE:To enhance the thermal durability and low-temp. activity of the title catalyst by depositing nickel and/or nickel oxide, etc., on the pulverized gamma-alumina or hydrated alumina carrier contg. a specified amt. of a sulfur compd. to obtain the catalyst. CONSTITUTION:Nickel and/or nickel oxide or its reduction product are deposited on the pulverized gamma-alumina or hydrated alumina carrier contg. <=1.2wt.% sulfur compd. (as SO4<2->) to obtain the catalyst for producing methane by the gaseous- phase catalytic reaction of methanol. The particle diameter of the carrier is appropriately controlled to about 30-100mu, and the content of the sulfur compd. in the carrier is adequately adjusted to <=1wt.% as SO4<2->. When the obtained catalyst is used for the conversion of methanol into a methane-contg. gas by the gaseous-phase catalytic reaction, the thermal durability is enhanced, and the high low-temp. activity and high methane yield are stably maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a catalyst for producing a methane-containing gas using methanol as a raw material.

In recent years, LNG has been used as a raw material for city gas mainly in metropolitan areas.
(liquefied natural gas), but in the case of LNG, it is necessary to transport and store it at an ultra-low temperature of -160℃, and there are technical and economic constraints in terms of handling, so it is not suitable for small and medium-sized cities. There are many mistakes in hiring. Therefore, there is an urgent need to complete an industrial technique for economically producing city gas containing methane by replacing LNG with methanol, which is easy to handle, as the city gas raw material.

The biggest problem in methanating methanol is that it is difficult to control the high reaction heat generated by the methanation reaction. Particularly when methanation is carried out using a multi-tubular reactor, the part of the inlet side of the catalyst layer is always at its lowest temperature due to the high reaction heat. :It is exposed to high temperatures of around 4,600°C (Figure 1). Note that this figure was measured under the following reaction conditions. Heat medium temperature 2300℃, LH8V: 1.0hr-' (methanol base), pressure crab 3kg/csi G 1H
20/methanol molar ratio -1.0° This heat usually causes a decrease in the activity of the catalyst, and the position of its exothermic peak gradually shifts to the exit side of the catalyst layer. Therefore, the catalysts used are required to have a high degree of thermal durability. Further, improvement in catalyst activity leads to lowering of the heat medium temperature, and the maximum temperature inside the catalyst layer can be lowered. Therefore, it goes without saying that this is advantageous in extending the life of the catalyst.

Furthermore, if the catalyst can maintain high activity stably for a long period of time and the heating medium temperature can be kept below 350°C, hot oil can be used instead of a nitrate bath, which has many problems in industrial handling. Since it becomes possible, it is advantageous in terms of process and has great economic merit.

Therefore, the catalyst used for the methanation reaction with good thermal durability must have the ability to maintain low-temperature activity and maintain a high methane yield even after a reaction history at high temperatures. This is also essential for the long-term stable operation of an economical gasification plant.

Prior Art The following catalysts have been proposed as catalysts for converting methanol into methane-containing gas through gas phase catalytic reaction.

(1) Nickel catalyst with activated aluminum and/or diatomaceous earth as a carrier (JP-A-51-122102) (2) 25 to 50% by weight of nickel, at least 5% by weight of alumina fused cement, zirconium dioxide or carbon dioxide A catalyst containing at least 5% by weight of titanium (JP-A-53-35702 and JP-A-54-111503) (3) On a carrier containing an oxide of an alkaline earth metal element or an oxide of a rare earth metal element. Catalyst for producing methane-containing gas using methanol or a mixture of methanol and water as a raw material, characterized by supporting nickel or nickel oxide (JP-A-60-209253, JP-A-60-2)
However, as far as the present inventors know, these catalysts have poor initial low-temperature activity, poor low-temperature activity of the catalyst after high-temperature reaction, and have so far suffered from poor heat resistance and methane yield. leaves many problems unsolved.

Abstract As a result of many years of research, the present inventors have developed a catalyst that has high thermal durability and stably maintains high low-temperature activity and high selectivity when producing methane-containing gas using methanol or methanol and water as raw materials. I found out.

That is, the catalyst for the production of methane by vapor phase catalytic reaction of methanol according to the present invention has a sulfur compound content (So
2->1. 21i amount% or less of fine powder γ-
It is characterized in that nickel and/or nickel oxide or its reduction product is supported on alumina or a finely powdered alumina hydrate carrier.

Effects As described above, the catalyst of the present invention has high thermal durability when converting methanol to a methane-containing gas by gas phase catalytic reaction, and stably maintains high low-temperature activity and high methane yield. .

One of the characteristics of the catalyst of the present invention is that the content of sulfur compounds in the carrier is kept low. Although this point may seem to be in conflict with the reduction of the content of catalyst poisons, the above points The effect, especially the effect of improving heat resistance, is not expected from simply lowering the content of catalyst poison.

[Detailed description of the invention]

The finely powdered γ-alumina or alumina hydrate used as the catalyst carrier has a particle size of approximately 30 to 100μ, and is prepared by an appropriate method from an appropriate alumina source compound, for example, from page 33 of “Elemental Catalyst Handbook”. The method described on page 39,
It can be created by Here, "fine powder" means
This means that substantially the entire amount passes through the 48 mesh sieve.

The catalyst according to the invention is characterized in that the content of sulfur compounds in the carrier is 1.2% by weight or less, preferably 1% by weight or less, more preferably 0.8% by weight or less as So2-. It is.

The sulfur compound content in the carrier was measured by fluorescent X-ray analysis.

Manufacture of Catalyst The catalyst according to the present invention has nickel and/or nickel oxide or its reduced product supported on the above-mentioned carrier. Here, the term "reduced oxide" includes those whose oxidation stage is lower than that of the starting oxide, up to metal hydrides.

The method for obtaining the catalyst of the present invention by supporting these catalyst components on the carrier as described above is arbitrary, and any conventionally used method can be adopted.

For example, to a solution of salts such as nickel nitrates, chlorides, sulfates, organic acids or chelates, an alkali such as alkali bicarbonate or alkali carbonate is added to precipitate, and the precipitate is filtered and washed, and then formed into a fine powder carrier. The catalyst according to the invention can be obtained by kneading, drying, calcining, shaping and hydrogen reduction.

The quantitative ratio of nickel, which is an essential component, and the carrier is arbitrary as long as the intended purpose is achieved, but in general, a range of 25 to 75% in terms of Ni loading rate is appropriate.

In the above method, there is no problem in allowing a fine powder carrier to coexist during precipitation.

In addition, the "catalyst" as used in the present invention may be a columnar, tablet-shaped, honeycomb-shaped, plate-shaped or other molded product when used in the methanol reforming reaction, if the carrier in the supporting step is in the form of fine powder. Needless to say, this is a good thing. Furthermore, other metal components may be present in addition to nickel for the purpose of promoters, etc., as long as the spirit of the present invention is not impaired.

Methanol reforming The catalyst obtained in the above manner has high low-temperature activity and high methane yield even in continuous high-temperature reactions for the reaction of reforming methanol or a mixture of methanol and water into a methane-containing gas as a raw material. It has excellent retention performance.

When producing methane from methanol-water, the theoretical molar yield of methane is 75 mol% according to the following reaction formula.

4CHOH+H20→ 3CH4+Co2+3H20 Experimental Example Example-1 An aqueous solution containing N1(NOs)2.6H20495tr and an aqueous solution containing 287g of sodium bicarbonate (twice the mole of nickel nitrate) as a precipitant were reacted.
Precipitation occurs at 30°C. The precipitate was filtered and further washed thoroughly with pure water. Next, a slurry of this precipitate and alumina hydrate (S042
- Content: 0.1% by weight) and 179 g were thoroughly kneaded.

This was dried while being mixed, then baked at 600℃ for 3 hours.
Molding (3φ×4mm) was performed to obtain catalyst-1. Boehmite gel (So2 content 70.22% by weight) 130. , γ-alumina (So
Catalysts 2, 3 and 4 were prepared using 114i of γ-alumina (S04 content: 0.29% by weight) and 114g of γ-alumina (S04 content: 0.54% by weight). All of Catalysts-1 to 4 had a nickel support rate of 50% by weight.

These catalysts were charged into a reactor and then reduced at 400° C. for 2 hours in a hydrogen stream. An initial activity evaluation test was conducted under the conditions shown in Table 1, and the results shown in Table 2 were obtained.

Further, these catalysts were subjected to high-temperature reactions for 45 hours under the conditions shown in Table 1, except that the reaction heat medium temperature was 580°C, and then an activity evaluation test was conducted to obtain the results shown in Table 3.

Note that hydrogen reduction and activity evaluation of the catalyst were also carried out using this method in Comparative Example and Example-2 described below.

Comparative Example Catalysts were prepared in the same manner as in Experimental Example-1, using 130 g of boehmite gel (S042 content = 1.4 wt%) and boehmite gel (S04 content: 2.5 wt%) as carriers, respectively. 130
g, γ-alumina (S04 content: 2.5% by weight) 1
A catalyst was prepared using 14 g to obtain Comparative Catalysts-1 to 3. All of these have a nickel loading rate of 50% by weight. The results of these activity evaluation tests are shown in Tables 2 and 3 together with Example 1.

Example-2 The same carrier as catalyst-2, boehmite gel (S0
Catalyst-5 was prepared by the method of Example-1 except that anhydrous sodium carbonate was used as the precipitant. The nickel loading rate of this catalyst was 50% by weight. The initial activity evaluation test results of this catalyst and the activity evaluation test results after high temperature reaction are also shown in Table 4.

Table-4

[Brief explanation of drawings]

FIG. 1 is a diagram showing the temperature distribution within the catalyst layer of a multi-tubular reactor.

Claims (1)

[Claims] Sulfur compound content (as SO_4^2^-) 1.2
Methane obtained by gas phase catalytic reaction of methanol, characterized by supporting nickel and/or nickel oxide or its reduction product on a fine powder γ-alumina or fine powder alumina hydrate carrier in a weight percent or less Catalyst for the production of.