JPS60158120A - Production of methane - Google Patents

Abstract

PURPOSE:To effect the desorption and regeneration of S from an incompletely sulfurized sulfur-resistant shift reaction catalyst, by contacting the catalyst with a feed gas containing CO, H2 and S together with steam to effect the adsorption of S to the catalyst, and contacting the gas with a methanization catalyst. CONSTITUTION:The feed gas CG is supplied in combination with steam Stm to the shift reaction catalyst bed 1A to effect the shift reaction and desulfurization. The other catalyst bed 1B containing the shift reaction catalyst having lowered desulfurization activity is supplied with the regeneration gas RG (e.g. steam, H2, air, etc.) to remove the S component in the form of H2S, SO2, etc. and regenerate the catalyst. The flow of the feed gas to the catalyst beds 1A and 1B is switched alternately to carry out the continuous shift reaction and desulfurization. The gas is cooled to 220-400 deg.C after the reaction, and supplied to the methanization reaction catalyst bed 2 to obtain methane gas Met. The shift reaction catalyst is preferably an Ni(or Co)-Mo-K2CO3 catalyst supported on alumina.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for producing methane using a gas containing sulfur as well as CO and H2 as a raw material.

For example, gas produced by gasifying coal or heavy oil,
In the case of catalytic methanation reaction to produce methane, GO+ 3 H2→ Cto14 + )→ 20GO
+4H2→ CH4+ 2 t- (20 The conventional method is to first make the ratio of CO and 1-12 in the produced gas to a value suitable for the methanation reaction, by blowing steam into it to carry out a catalytic shift reaction. This is what we do.

CO+t-120-+ CO2+H However, if the Kanayama shift reaction is carried out, too much t-12 will be present, so a part of it is bypassed.

The gas after the shift reaction is cooled to condense and remove excess steam, and is mixed with the bypassed gas at a ratio such that the H2/GO ratio is approximately 3 for use.

Since the gasification reaction product usually contains a considerable amount of sulfur, the catalyst for the shift reaction is a sulfur-resistant catalyst, such as alumina-supported X+ or Co.
) Mo − is used in a state in which a 2GO3-based catalyst is sulfurized.

Since sulfur content is harmful to commonly used methanation reaction catalysts, it is necessary to remove it prior to methanation.
CO2 and H2S were removed and sent to the methanation step. Sulfur-resistant methanation catalysts are also being developed, but they fall short of known catalysts in terms of activity and other aspects.

The present inventors have developed the above-mentioned gasification-shift reaction-〇 〇
The purpose of this research was to rationalize the series of processes of 2/l-12S removal and methanation reaction. In the process, when steam is applied to the sulfur-resistant shift catalyst in a sulfurized state, it decomposes and releases sulfur, and the shift reaction catalyst, which is in an unsulfurized or incompletely sulfurized state, adsorbs and removes the sulfur. We found that the shift activity was maintained to a considerable extent while having the function of desulfurization, and we established and separately proposed a method to perform the shift reaction and desulfurization at the same time. Further research led to the completion of a process that combines this shift reaction and desulfurization method with methanation, leading to the present invention.

The method for producing methane of the present invention includes COJ> and ('2
This is a method for producing methane from a raw material gas containing 1 and 2 A and 2 A, and is a method in which the raw material gas is brought into contact with a sulfur-resistant Schiff I reaction catalyst in an unsulfurized or incompletely sulfurized state. Schiff 1 ~ Reaction When dividing all reactions, A in the gas is adsorbed onto the Schiff 1 ~ reaction catalyst! (This gas is brought into contact with a methanation catalyst to produce methane, and a regeneration gas is applied to the reaction catalyst in a sulfurized state to adsorb sulfur, thereby converting the catalyst. It consists of avoiding regeneration.

As the anti-A Schiff 1 reaction catalyst, the above-mentioned Ni
2GO3/A 203 system for (co)-MO- (instead of pu, Fe 203-Or 203 system can also be used. It is sufficient that the catalyst can be decomposed and recovered using a regeneration gas and can be regenerated.

Here, "1 regeneration of the catalyst" means recovery of desulfurization ability. The shift activity is higher in highly sulfided states, but it remains at a practical level even in low-sulfided states where desulfurization (ability) is sufficiently high.

The shift reaction is carried out under conditions known to be suitable for each catalyst.
2GO3/A to O-, 1! , 203 series Teha, Ona 20
What is necessary is just to carry out in the range of 0-4-50 degreeC, pressure 2-50K(]/cm'G1 space velocity 500-5000/hr.

Of course, the shift reaction d3 and the desulfurization must end at a point where the sulfur adsorption capacity of the catalyst is saturated. Under the usage conditions in each case, determine the breakthrough point, that is, the time required for the sulfur compound to flow out to the reactor outlet, and stop the reaction with some margin (for example, when 95% of the breakthrough time has passed). You should switch to playback.

In addition to the above-mentioned steam, the regeneration is carried out by applying fluorine, air, or a mixture of two or three of these under heating to remove the sulfur content adsorbed on the shift reaction catalyst. The regeneration rate, that is, the percentage of adsorbed sulfur to be desorbed, must be determined by finding a compromise between the two, since the higher the regeneration rate, the higher the desulfurization ability, but the lower the Schiff 1 reaction activity. 'Generally, about 50 to 70% would be appropriate. The higher the humidity, the faster the regeneration, but if the humidity exceeds 600°C, the MOO3 in the catalyst component will fold, which is undesirable. A lower pressure and a higher space velocity are advantageous for regeneration. These conditions are preferably selected so that the regeneration rate within the above-mentioned preferred range can be achieved in a time shorter than the time required for the shift reaction and desulfurization.

As understood from the above, the method of the present invention, as far as the shift reaction is concerned, can achieve continuous shift reaction - methane by preparing two or more catalyst beds and using them alternately. reaction is realized. That is, as shown in FIG. 1, the gas CG produced by gasification is supplied to the shift reaction catalyst bed 1Δ together with 3 tm of steam to carry out the shift reaction and desulfurization. Regeneration gas RG is supplied to the catalyst bed 1B having a shift reaction catalyst with a reduced desulfurization function, and the sulfur content is removed by H2SXSO2,3x
The catalyst is regenerated by removing it in the form of

If the catalyst in the catalyst bed 1A adsorbs a large amount of sulfur and its desulfurization function becomes low, while the catalyst in the catalyst bed 1B recovers its desulfurization function, the flow of gas supplied to both may be changed.

The gas obtained by continuously performing the shift reaction and desulfurization in this way is heated to a temperature suitable for the methanation reaction, that is, 220°C.
It is cooled to ~400°C and supplied to the methanation reaction catalyst bed 2. The gas produced by the methanation reaction is recycled by separating unreacted raw materials in a fractionator 3, and the methane fraction is sent to a CO2 removal device 4 for purification to obtain 1 vol of product methane gas.

Since the methanation reaction is accompanied by a large amount of heat generation, it is preferable to use steam to control it. Excessive temperature rise is suppressed by utilizing the equilibrium of the reaction described above. To achieve this, it is sufficient to send the steam remaining from the reaction to Schiff 1 to the methanation reaction catalyst without removing it from the raw material gas, which results in less energy than the method of condensing and removing the steam that has been applied and then adding steam again. This is advantageous because there are fewer problems and the equipment is simpler.

According to the method of the present invention, there is no need to use a sulfur-resistant catalyst for the methanation reaction, and in combination with the above-mentioned temperature controller using steam, the methanation process can be carried out advantageously. . In the process of removing C02,
Unlike the prior art, since methanation is carried out on the stream and the volume of gas is reduced, a small device is sufficient. Also, in the emitted CO2, t-12S etc.
Since there are no mixed components, there are no environmental problems.

An experimental apparatus having the configuration shown in FIG. 2 was constructed, and reactor 1 was filled with a sulfur-resistant shift reaction catalyst, and reactor 2 was filled with a methanation reaction catalyst.

6 is a steam generator for the Schiff 1 reaction, and 7 is a steam generator for regeneration.

Assuming coal gasification gas as the raw material gas, a simulated gas having the composition shown in Table 1 was prepared.

-1-K H256, 3% by volume CH411, 5% by volume C030,
6〃 N2 0.6 〃 CO21, On H2S 500111) N2 inside the m system
After purging with gas, 1 and 2 gases were flowed to raise the temperature of the methanation catalyst and activate it.

Next, the temperature of the shift catalyst was raised, and the raw material gases and steam shown in Table 1 were supplied in place of l-12 to start the shift reaction.

When the reaction conditions were maintained as shown below and the reaction continued, the following results were obtained: To120 (steam)/raw material gas = 3 Space velocity Schiff 1 - 1000/hr for the catalyst, 3000/hr for the methanation catalyst Reaction temperature (both) 350℃ Pressure (both) 9! J/cm2-G After 5 hours, a gas having the composition 1 shown in Table 2 was obtained.

Even if the reaction continues for 15 hours, 1-1 remains in the outlet gas of reactor 1.
28 was not detected (detection limit 1 ppn+).

f12 66.2 volume% 50.1 volume% CO0,9I
I O171I CO223,5 no J 23, 3 CF+4. 8
．． 9 II 25.2 nN2 0.5 n O, 7n It's lppm or less 1 ppm or less Kass volume ratio raw material gas/Schif 1~ output log gas/methanation output log gas = 1/
1.2910. After stopping the gas supply to the '88 methanation catalyst and releasing the gas at the outlet of the reactor 1, 1''2S was fed at a concentration of about 1% by volume. 1-12 at the outlet of reactor 1
After confirming that 8 was leaking, the supply of -128 was stopped, and gas was again supplied to the methanation catalyst in reactor 2. When the above reaction conditions were maintained, a decrease in the activity of the methanation catalyst was observed, and after 5 hours, the gas composition at the outlet of reactor 2 became as shown in Table 3.

12 66.3% by volume 66.9% by volume CO0.8l!
0.6 〃 C0223,5〃 23.6 II Cto14 9. OJ/ 9.4 /j N2 0.4 // 0.4 n H2S 470ppm 15ppm The reaction was stopped, steam and air were supplied from the bottom of reactor 1, and the shift reaction catalyst layer was kept at 350°C for 10 hours. Afterwards, the system was purged with N2 gas. After replacing the methanation catalyst and activating each of the catalysts described above, a shift reaction and a methanation reaction were performed under the same conditions as above, and the results shown in Table 2 were reproduced. Even after continuing the reaction for 15 hours, no 1'2S was found in the outlet gas of reactor 1.

[Brief explanation of the drawing]

FIG. 1 is flowchart +7-1 to explain the method of producing methane of the present invention. FIG. 2 is a flow chart 1 showing the experimental apparatus used in Example C of the present invention. 1△, 1B...Shift reaction catalyst bed 2...
・Methanation reaction catalyst bed 3...Fraction distillation device 4...GO2 removal device CG...Coal casing product 3tm...Steam RG... ...Regeneration gas 1yjet...Methane gas patent applicant JGC Corporation Company agent Patent attorney Souo Suga

Claims (4)

[Claims] (1) A method for producing methane from a raw material gas containing sulfur as well as Go and H2, which comprises bringing the raw material gas into contact with steam and a sulfur-resistant shift reaction catalyst in an unsulfurized or incompletely sulfurized state. While performing a shift reaction, sulfur in the gas is removed by adsorption to a shift reaction catalyst, and this gas is brought into contact with a methanation catalyst.
A method for producing methane, which comprises producing C methane, causing a regeneration gas to act on a shift reaction catalyst that has reached a sulfurized state, and regenerating the catalyst by depositing sulfur on the catalyst. (2) A patent for preparing a plurality of catalyst beds for shift reaction catalysts, switching them over and using them alternately, performing shift reactions and sulfur adsorption reactions in some of the catalyst beds, and regenerating the desulfurization function in other catalyst beds during that time. The method according to claim 1. (3) The method according to claim 1, wherein the shift reaction catalyst is an alumina-supported Ni (or Co)-MO-2GO3-based catalyst. (4) The method according to claim 1, wherein steam, H2, air, or a mixture of two or three thereof is used as the regeneration gas.