JPH05285341A - Treatment of carbon dioxide - Google Patents

Abstract

PURPOSE:To obtain a method for treating carbon dioxide where LaxSr1-xCoOdelta base perovskite-type compounds are used with their carbon dioxide adsorptive power being as high as possible. CONSTITUTION:In a method for treating carbon dioxide where carbon dioxide is brought into contact with LaxS1-xCoOdelta base (where x=0-0.8, delta=1-3) perovskite-type compounds and given adsorption by the compounds to treat it, after the compounds are given reducing treatment where they are brought into contact with reducing gas, such as gaseous hydrogen or gaseous methane in the temp. range of >=700 deg.C, they are brought into contact with carbon dioxide to treat it.

Description

Detailed Description of the Invention

[0001]

2. Description of the Related Art Conventionally, various methods such as a liquid absorption method such as an alkanolamine method, a hot potassium carbonate method, and a catacarb method, a membrane separation method, and an adsorption method have been adopted for removing and recovering carbon dioxide. However, each of these methods has drawbacks, and the advent of a method capable of sorption / removal / recovery of carbon dioxide with a relatively simple method / device configuration has been desired. Here, the above-mentioned La _x Sr _1-x
The CoOδ system (where x = 0 to 0.8, δ = 1 to 3) perovskite type compound meets such requirements, and this compound is disposed in a channel through which carbon dioxide flows. If it is kept, it can be sorbed and removed, and if an inert gas is further brought into contact with the sorbed compound, it will be released, so carbon dioxide can also be collected. Is.

[0002]

However, the carbon dioxide sorption capacity of this compound is limited, and there is a drawback that the carbon dioxide sorption capacity is limited if it is used without any treatment.

Therefore, it is an object of the present invention to provide La _x Sr _1-x Co.
To obtain a carbon dioxide treatment method in which this compound can be used in a state where the carbon dioxide sorption capacity of an Oδ system (where x = 0 to 0.8, δ = 1 to 3) perovskite type compound is as high as possible. Is.

[0004]

[Means for Solving the Problems] The characteristic means of the method for treating carbon dioxide according to the present invention for achieving this object is to perform a reduction treatment in which this compound is brought into contact with a reducing gas in a temperature range of 700 ° C. or higher. , Contact with carbon dioxide,
It is supposed to process carbon dioxide. Their actions and effects are as follows.

[0005]

In this method, reduction treatment is performed before contact with carbon dioxide. When this reduction treatment is performed, the oxygen defects formed by the elimination of oxygen contained in the structure of this compound, which is a perovskite type compound, increase from the normal one, and this oxygen defect part absorbs carbon dioxide. It is thought that it exerts. That is, by performing the reduction treatment, the treatment capacity for carbon dioxide can be increased.

[0006]

Effect of the Invention] Therefore, La _x Sr _1-x CoOδ system (wherein x = 0~0.8, δ = 1~3) as high as possible state carbon dioxide sorption capacity of a perovskite-type compound, the compound It was possible to obtain a carbon dioxide treatment method that could be used.

[0007]

The method for treating carbon dioxide of the present invention will be described below. This treatment method is based on the compound (La _0.2 Sr
_0.8 CoO δ (δ = 1 to 3) and subsequent δ is omitted)
And a second treatment in which a treated compound is used and carbon dioxide is brought into contact with it to perform a sorption treatment. That is, the reduction-processed L obtained by bringing a carbon dioxide-containing gas containing carbon dioxide into contact with a reducing gas such as hydrogen gas or methane gas in the flow path.
a _0.2 Sr _0.8 CoOδ is installed, and this installation part is 900 ° C.
Maintain to a degree. Then, the gas treated with carbon dioxide flows out to the downstream side. Here, the amount of reduction of carbon dioxide differs greatly between those subjected to reduction treatment and those not subjected to reduction treatment.

The status of each processing is listed below. (1) Compound reduction treatment Reduction gas H ₂ gas 100% or CH ₄ gas (25%)-N
₂ (balance) Treatment time 30 min Treatment temperature 900 ° C. SV value 1000 h ⁻¹ (2) Treatment of carbon dioxide Gas to be treated CO ₂ (12%)-N ₂ (88%) Reaction temperature 900 ° C. SV 1000 h ⁻¹ Results Table 1 As shown in, the CO ₂ adsorption treatment amount increased significantly.
Here, in the case where no reduction process is performed for comparison,
The amount of CO ₂ adsorbed when the compound was simply kept at 900 ° C. and nitrogen gas was supplied was 40 cc / 1 g.

[0009]

[Table 1]

Therefore, it is understood that the reduction treatment may double the sorption treatment amount of carbon dioxide.

[Experimental Example] Invention related to carbon dioxide treatment
The results of the experiments conducted by the researchers will be described below. (1) La_xSr_1-xCoOδ (x = 0 to 1, δ = 1 to 1
3) CO₂Treatment characteristics CO of this compound₂Processing characteristics La to Sr
FIG. 1 shows the processing result when the compounding ratio of No. 1 was changed. Experimental conditions Molded state of each compound Granule of 1-2 mm Reaction temperature 900 ° C CO₂Concentration 12% -N₂Balance SV 1000h^-1 As a result, this compound was 4 in the range of x of 0 to 0.2.
CO of about 0cc / g ₂Shows processing characteristics and further La amount
CO increases with₂Loss processing performance. Therefore, this
CO using compound₂Can be processed. x =
The range of 0.0-0.8 is the range where this compound works effectively.
is there.

[0012] (2) the relationship between the CO ₂ processing characteristics for CO ₂ processing characteristics and relationships La _0.2 Sr _0.8 CoOδ reaction temperature and SrCoOδ perovskite compound composition and the reaction temperature are shown in FIG. 2 together with the results of BaTiO _3. The experimental conditions are the same as those in FIG. As a result, reaction temperature 100
When changed to ~ 900 ° C, La _0.2 Sr _0.8 CoO
In the perovskite compound of δ and SrCoOδ composition,
It was confirmed that the treatment of carbon dioxide increased with the increase of the reaction temperature, and the adsorption / treatment of CO ₂ per reaction amount of about 40 cc / g of perovskite compound was confirmed at the reaction temperature of 900 ° C. On the other hand, with respect to BaTiO ₃ carried out in the same manner, CO ₂ adsorption / treatment could not be confirmed. Then, set the reaction temperature to 9
When the temperature was maintained at 00 ° C. and the N ₂ —CO ₂ gas was switched to the N ₂ gas, the same amount of CO ₂ released as the adsorbed amount could be confirmed. From this, it is understood that at the reaction temperature of 900 ° C., CO ₂ gas can be adsorbed / desorbed by switching the gas.

(3) La _0.2 Sr in various reduction treatments
Changes in CO ₂ sorption capacity of _0.8 CoOδ Various reduction treatments (heat treatment, CH ₄ treatment, H ₂ treatment) are shown in FIG.
The time-dependent change in the sorption capacity of La _0.2 Sr _0.8 CoO δ in the case of performing the above is shown. That is, the relationship between the CO ₂ concentration at the outlet side of the reactor in which the compound is disposed and the time elapsed from the removal start time (when the removal start time is 0:00) is shown. The respective reducing treatment conditions are as follows. Heat treatment (shown by a broken line) Processing gas; Nitrogen gas, processing temperature; 900 ° C., processing time;
30 min CH ₄ treatment (shown by alternate long and short dash line) treatment gas; CH ₄ gas (25% -N ₂ gas), treatment temperature;
900 ° C., processing time; 30 min H ₂ processing (shown by solid line) processing gas; hydrogen gas (100%), processing temperature; 900
C, treatment time; 30 min Carbon dioxide removal conditions Reaction temperature: 900 ° C., SV: 1000 h ⁻¹ , reaction gas:
CO ₂ 12% -N ₂ balance As a result, in this compound, 20 m was obtained by simple heat treatment.
It showed only about 100% removal capacity of in, but CH
₄ treatment, H ₂ treatment improves its removal ability,
_In the case of ₂ treatments, the treatment capacity of 100% was maintained for about 1 hour.

(4) SrCoOδ in various reduction treatments
Change in CO ₂ sorption ability of SrCoOδ The results of the same experiment were shown in FIG. The experimental conditions and various processes are the same as those in FIG. Results In this compound, but only showed a 100% throughput of about 20min just heat treatment in the same manner as FIG. 3, H ₂ treatment, improves the processing capacity according to a CH ₄ process, the CH ₄ treatment In case of about 50m
The processing ability of 100% was maintained. Here, it is considered that the reason why the treatment performance is reversed in FIGS. 3 and 4 is due to the oxygen defect structure in each compound and the structure of each reducing gas. [Other Embodiments] (a) In the above embodiments, examples of methane and hydrogen have been shown as the gas used for the reduction treatment, but this may be carbon monoxide gas, etc. And is referred to as reducing gas. (B) Each compound has only to satisfy the above-mentioned conditions in use, and the starting material in the synthesis process is not particularly limited, and the synthesis method is also a solid phase reaction method or a liquid phase reaction method. There is no particular limitation. (C) Further, the compound may be placed in a gas containing carbon dioxide in the form of particles, or may be formed into any shape such as a honeycomb shape and used.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing the CO ₂ treatment performance of a cobalt acid compound.

FIG. 2 is a graph showing the relationship between CO ₂ removal rate and reaction temperature.

FIG. 3 shows La _0.2 Sr _0.8 CoOδ in various reduction treatments.
Figure showing CO ₂ sorption capacity

FIG. 4 is a diagram showing changes in CO ₂ sorption capacity of SrCoOδ during various reduction treatments.

Front page continuation (72) Shigeru Morikawa, Inventor Shigeru Morikawa, Nakagyo-dera, Shimogyo-ku, Kyoto Prefecture, Kyoto, Ltd.Kansai Research Institute of Technology (72) Inventor, Takashi Kobayashi 17, Nakado-dera, Minami-cho, Kyoto, Kyoto Inside the New Technology Research Institute (72) Inventor Tadao Ohnaka 17 Nakadoji Minami-cho, Shimogyo-ku, Kyoto City Kyoto Prefecture

Claims (2)

[Claims] 1. Carbon dioxide is brought into contact with a La _x Sr _1-x CoO δ system (where x = 0 to 0.8, δ = 1 to 3) perovskite type compound, and the carbon dioxide is sorbed to the compound. In the method for treating carbon dioxide, the carbon dioxide is treated by subjecting the compound to a reducing gas in a temperature range of 700 ° C. or higher, and then contacting the carbon dioxide to treat the carbon dioxide. How to treat carbon dioxide. 2. The method for treating carbon dioxide according to claim 1, wherein the reducing gas is hydrogen gas or methane gas. [Industrial application] Carbon dioxide is converted into La _x Sr _1-x CoO
The present invention relates to a method for treating carbon dioxide, which comprises contacting a δ-based (where x = 0 to 0.8, δ = 1 to 3) perovskite type compound to sorb carbon dioxide to the compound to treat the carbon dioxide.