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JP3737574B2 - Carbon dioxide separation method and carbon dioxide separation membrane - Google Patents
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JP3737574B2 - Carbon dioxide separation method and carbon dioxide separation membrane - Google Patents

Carbon dioxide separation method and carbon dioxide separation membrane Download PDF

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JP3737574B2
JP3737574B2 JP24505796A JP24505796A JP3737574B2 JP 3737574 B2 JP3737574 B2 JP 3737574B2 JP 24505796 A JP24505796 A JP 24505796A JP 24505796 A JP24505796 A JP 24505796A JP 3737574 B2 JP3737574 B2 JP 3737574B2
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carbon dioxide
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lithium
separation membrane
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JPH1085552A (en
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和明 中川
秀行 大図
芳浩 赤坂
師浩 富松
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Toshiba Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/40—Capture or disposal of greenhouse gases of CO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2

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Description

【０００１】
【発明が属する技術分野】
本発明は、炭酸ガス分離方法および炭酸ガス分離膜に関し、特に炭化水素を主成分とする燃料を利用するエネルギープラントや化学プラント等から発生する排出ガス中の炭酸ガスを分離回収する方法および炭酸ガス分離膜に係わる。
【０００２】
【従来の技術】
炭酸ガスの分離方法としては、従来より酢酸セルロースを用いる方法、アルカノールアミン系溶媒による化学吸収方法等が知られている。
しかしながら、前述した分離方法はいずれも導入ガス温度を２００℃以下に抑える必要がある。したがって、高温度のリサイクルを要する排気ガスに対しては一旦、熱交換器等により２００℃以下に冷却する必要があり、結果的に炭酸ガス分離ためのエネルギー消費量が多くなるという問題があった。
【０００３】
【発明が解決しようとする課題】
本発明は、エネルギープラントや化学プラント等の排気ガス中の炭酸ガスを低エネルギー消費量、高効率で分離回収することが可能な炭酸ガス分離方法並びに安定性の高い炭酸ガス分離膜を提供しようとするものである。
【０００４】
【課題を解決するための手段】
本発明に係る炭酸ガス分離方法は、５００℃以上の雰囲気下で炭酸ガスと反応して溶融炭酸リチウムを生成する複合酸化物を含む領域を挟んで相対的に高い分圧の炭酸ガスを含む第１の気体と相対的に低い分圧の炭酸ガスを含む第２の気体をそれぞれ流す第１工程と、
前記領域中の複合酸化物を５００℃以上に加熱して第１の気体と前記領域との接触部において前記第１の気体中の前記炭酸ガスと前記複合酸化物とを反応させて溶融炭酸リチウムを生成する第２工程と、
前記領域と前記第２の気体を接触部において、前記領域中の溶融炭酸リチウムを分解させて炭酸ガスを生成し、前記領域から前記第２の気体に放出すると共に前記領域中に再び複合酸化物を生成する第３工程と
を具備し、
前記第２、第３の工程を複数回繰り返すことを特徴とするものである。
【０００５】
本発明に係わる別の炭酸ガス分離方法は、リチウムジルコネートを含む領域を挟んで相対的に高い分圧の炭酸ガスを含む第１の気体および相対的に低い分圧の炭酸ガスを含む第２の気体をそれぞれ流す第１工程と、
前記領域中のリチウムジルコネートを５００℃以上に加熱して前記第１の気体と前記領域との接触部において前記第１の気体中の前記炭酸ガスと前記リチウムジルコネートとを反応させて溶融炭酸リチウムとジルコニアを生成する第２工程と、
前記領域と前記第２の気体を接触部において、前記領域中の溶融炭酸リチウムを分解させて炭酸ガスを生成して前記領域から前記第２の気体に放出すると共に、分離されたリチウムを前記領域を拡散させて前記第１の気体側でジルコニアと反応してリチウムジルコネートを再び生成する第３工程とを具備し、
前記第２、第３の工程とを複数回繰り返すことを特徴とするものである。
【０００６】
本発明に係る炭酸ガス分離膜は、５００℃以上で炭酸ガスと反応して溶融炭酸リチウムを生成する複合酸化物および５００℃以上で溶融するアルカリ炭酸塩からなる分離膜本体と、
前記本体の炭酸ガスと反応する側と炭酸ガスを放出する側とにそれぞれ配置され多孔質支持部材と
を具備したことを特徴とするものである。
【０００７】
【発明の実施の形態】
以下、本発明を図１を参照して詳細に説明する。
図１は、本発明の炭酸ガス分離膜を示す概略図である。図中の１は、分離膜本体である。この分離膜本体１は、５００℃以上で溶融するリチウムを主体とするアルカリ炭酸塩、例えば炭酸リチウム（Ｌｉ2 ＣＯ3 ）と炭酸カリウム（Ｋ2 ＣＯ3 ）との混合炭酸塩２またはこの混合炭酸塩２に分散された炭酸ガスと反応して炭酸塩を生成する複合酸化物、例えばリチウムジルコネート（Ｌｉ2 ＺｒＯ3 ）粒子３から構成される。なお、前記分離膜本体１は前記混合炭酸塩２にジルコニア（ＺｒＯ2 ）粒子を分散させて、前記混合炭酸塩２中の炭酸リチウムとＺｒＯ2 粒子とを反応させて複合酸化物であるＬｉ2 ＺｒＯ3 粒子を生成してもよい。前記分離膜本体１は、前記混合炭酸塩に対して安定な材料、例えばリチウムアルミネートからなる多孔質支持部材４、５により両側から支持されている。
【０００８】
前記Ｌｉ2 ＺｒＯ3 粒子は、０．４〜１．０μｍの粒径を有することが好ましい。前記Ｌｉ2 ＺｒＯ3 粒子の粒径を０．４μｍ未満にすると、粒子の安定性が低下して相互の凝集・粒成長を起こす恐れがある。一方、前記Ｌｉ2 ＺｒＯ3 粒子の粒径が１．０μｍを越えると炭酸ガスとの反応面積が小さくなって、炭酸リチウム（Ｌｉ2 ＣＯ3 ）の生成速度が低下して、結果として炭酸ガスの分離性能が低下する恐れがある。
【０００９】
前記混合炭酸塩は、炭酸リチウム（Ｌｉ2 ＣＯ3 ）５５〜７０モル％と炭酸カリウム（Ｋ2 ＣＯ3 ）３０〜４５モル％とからなることが好ましい。
前記混合炭酸塩の量は、前記Ｌｉ2 ＺｒＯ3 粒子に対して１０〜３３重量％にすることが好ましい。
【００１０】
前記分離膜本体は、例えば次のような方法により作製される。
まず、０．４〜１．０μｍの粒径のＬｉ2 ＺｒＯ3 粒子を例えば溶媒である２−ブタノール、フタル酸ジブチル、およびバインダであるポリビニルブチラールと共に湿式混合してスチラリーを調製し、ドクターブレード法によりフィルム化し、加熱脱脂して、Ｌｉ2 ＺｒＯ3 粒子を含む多孔質体を形成する。次いで、この多孔質体に例えば炭酸リチウム（Ｌｉ2 ＣＯ3 ）６２モル％と炭酸カリウム（Ｋ2 ＣＯ3 ）３８モル％からなる混合炭酸塩を前記Ｌｉ2 ＺｒＯ3 に対して１０〜３３重量％になるように溶融含浸することにより分離膜本体を作製する。
【００１１】
前記分離膜本体の作製において、多孔質体中にリチウムアルミネート粒子を共存させることを許容する。
前記分離膜本体の作製において、前記多孔質体はドクターブレード法の他に、ゾル・ゲル法またはＣＶＤ法により多孔質支持部材上に形成してもよい。
【００１２】
次に、前述した炭酸ガス分離膜による炭酸ガス分離方法を説明する。
ジルコニウムとリチウムを主体とする酸化物とリチウムを主体とするアルカリ炭酸塩との系において、例えば下記（１）式によって炭酸ガスを吸収し、（２）式によって炭酸ガスを放出する。
【００１３】

Figure 0003737574
前記系が５００〜９００℃の温度域において、相対的に高い炭酸ガス分圧の下では前記（１）式の反応が特に起こり易く、相対的に低い炭酸ガス分圧の下では前記（２）式の反応が特に起こり易い。
【００１４】
前述した図１において多孔質支持体４側を相対的に高い分圧（例えば０．７ａｔｍ）の炭酸ガスを含む第１の気体６とし、多孔質支持体５側を相対的に低い分圧（例えば０．２ａｔｍ）の炭酸ガスを含む第２の気体７とする。
【００１５】
前記多孔質支持体４、５で両側から支持された分離膜本体１を５００℃以上に加熱すると、炭酸ガス分圧の高い第１の気体６との接触部において前記第１の気体６中の前記炭酸ガスは前記（１）式に従って分離膜本体１のＬｉ2 ＺｒＯ3 粒子３と反応してＬｉ2 ＣＯ3 （液体）として吸収され、Ｌｉ2 ＺｒＯ3 粒子はＺｒＯ2 粒子に変換される。このような反応により、溶融状態の混合炭酸塩２が存在する分離膜本体１において、炭酸ガス分圧の高い第１の気体６の接触部で溶融炭酸リチウムの濃度が炭酸ガス分圧の低い第２の気体７の接触部に比べて高くなる濃度勾配を示すため、溶融炭酸リチウムは前記混合炭酸塩２部分で第１の気体６の接触部側から第２の気体７の接触部側に移動する。
【００１６】
前記分離膜本体１の前記第２の気体７との接触部において、前記（２）式に従ってＺｒＯ2 （固体）の存在下でＬｉ2 ＣＯ3 （液体）が分解されて炭酸ガス（ＣＯ2 ）を生成し、その炭酸ガスは前記分離膜本体１から前記第２の気体７に放出されると共にリチウムは前記分離膜本体１中でＬｉ2 ＺｒＯ3 （固体）の形態で取り込まれる。
【００１７】
すなわち、前記多孔質支持体４、５で両側から支持された分離膜本体１を５００℃以上に加熱すると、炭酸ガス分圧の高い第１の気体６との接触部において炭酸ガスが吸収されると、溶融炭酸リチウムの高濃度化がなされると共に、複合酸化物粒子３はジルコニア（ＺｒＯ2）のようなリチウムを放出した形態になる。一方、前記分離膜本体１における炭酸ガス分圧の低い第２の気体７との接触部において炭酸ガスが放出されると、溶融炭酸リチウムの低濃度化がなされると共に、複合酸化物粒子３はＬｉ2ＺｒＯ3のようなリチウムを取り込んだ形態になる。
【００１８】
したがって、溶融炭酸リチウムは分離膜本体１中での濃度勾配により前記第１の気体６との接触部から前記第２の気体７に向かって移動する、つまり前記第２の気体７との接触部に前記（２）式の炭酸ガスの放出を担うように補給され、一方、リチウムは分離膜本体１中での濃度勾配により前記第２の気体７との接触部から前記第１の気体６との接触部に向かって固相拡散し、前記第１の気体６との接触部で前記反応式（１）の炭酸ガスの吸収を担うＬｉ2 ＺｒＯ3 を生成するという循環がなされる。特に、リチウムは固相拡散速度が高いめに前記第１の気体６の接触部にＬｉ2 ＺｒＯ3 の形態で存在させるためのリチウムの供給を迅速に行うことができる。このような５００℃以上の分離膜における溶融炭酸リチウムの移動およびリチウムの固相拡散により第１の気体６中の炭酸ガスを吸収し、第２の気体７に炭酸ガスを放出することができるため、第１の気体６中の炭酸ガスを前記分離膜を通して第２の気体７側に分離回収することができる。
【００１９】
以上説明した本発明によれば、従来では困難であった５００℃以上の高温の排気ガス中の炭酸ガスを高効率、低コストで分離できる炭酸ガス分離方法、および分離性能が安定した炭酸ガス分離膜を提供できる。
【００２０】
【実施例】
以下、本発明の好ましい実施例を詳細に説明する。
（実施例）
まず、平均粒径１．０μｍ程度のＬｉ2 ＺｒＯ3 粒子をフタル酸ジブチルおよびポリビニルブチラールと共に２０時間湿式混合してスチラリーを調製し、ドクターブレード法により厚さ１０μｍ程度のフィルムとした。
【００２１】
また、平均粒径１０μｍ程度のリチウムアルミネート粒子をフタル酸ジブチルおよびポリビニルブチラールと共に２０時間湿式混合してスチラリーを調製し、ドクターブレード法により厚さ１００μｍ程度のフィルムとした。
【００２２】
次いで、前記Ｌｉ2 ＺｒＯ3 粒子を服務フィルムをリチウムアルミネート粒子を含む２枚のフィルムで挟み込むようにして積層し、加熱脱脂した後、炭酸リチウム（Ｌｉ2 ＣＯ3 ）６２モル％と炭酸カリウム（Ｋ2 ＣＯ3 ）３８モル％からなる混合炭酸塩を前記Ｌｉ2 ＺｒＯ3 に対して２０重量％になるように溶融含浸し、さらに１００ｃｍ2 の大きさに切り出すことにより前述した図１に分離膜本体１の両側をリチウアムアルミネートからなる多孔質支持体４、５で支持した炭酸ガス分離膜を作製した。
【００２３】
次いで、図２に示すように得られた炭酸ガス分離膜８を図２に示すように容器９の中央部に配置して室１０、１１に上下に区画した。前記容器９の右側面に連結された上部側ガス導入菅１２から上部室１０に６００℃、３気圧、ＣＯ2 １０体積％、Ｎ2 ７５体積％、Ｏ2 ３体積％、Ｈ2 Ｏ１２体積％からなるガスを導入し、左側面に連結された排気管１３から排気した。同時に、前記容器９の左側面に連結された下部側ガス導入菅１４から下部室１１に６００℃、０．８気圧のＮ2 を３２００ｃｍ3 満たした。このような状態を１４分間保持した後、排気管１５から下部室１１のガスを取り出してその状態を調べた。その結果、６００℃、１気圧でＣＯ2 ２０体積％、Ｎ2 ８０体積％担っており、標準状態で２００ｃｍ3 の炭酸ガスの透過が認められた。
【００２４】
また、前記容器９の上部室１０内に前記組成の炭酸ガスを含むガスを１０００時間流通した後、下部室１１に０．８気圧のＮ2 を３２００ｃｍ3 満たした。その結果、同等の炭酸ガス透過性を示した。
【００２５】
（比較例）
図２に示す分離膜の代わりに酢酸セルロース膜を用いたところ、前記組成のガスを２００℃に昇温することができなかった。
【００２６】
【発明の効果】
以上詳述したように本発明によれば、エネルギープラントや化学プラント等の排気ガス中の炭酸ガスを低エネルギー消費量、高効率で分離回収することが可能な炭酸ガス分離方法並びに安定性の高い炭酸ガス分離膜を提供することができる。
【図面の簡単な説明】
【図１】本発明に係わる炭酸ガス分離膜および分離方法を説明するための概略図。
【図２】本発明の実施例における炭酸ガス分離装置を示す概略図。
【符号の説明】
１…分離膜本体、
２…混合炭酸塩、
３…リチウムジルコネート粒子、
４、５…多孔質支持部材、
６…第１の気体、
７…第２の気体、
８…炭酸ガス分離膜、
９…容器。[0001]
[Technical field to which the invention belongs]
The present invention relates to a carbon dioxide separation method and a carbon dioxide separation membrane, and in particular, a method for separating and recovering carbon dioxide in exhaust gas generated from an energy plant, a chemical plant, or the like that uses a fuel mainly composed of hydrocarbons, and carbon dioxide. Related to separation membrane.
[0002]
[Prior art]
Conventionally known methods for separating carbon dioxide include a method using cellulose acetate, a chemical absorption method using an alkanolamine solvent, and the like.
However, any of the above-described separation methods needs to suppress the introduced gas temperature to 200 ° C. or lower. Therefore, it is necessary to temporarily cool the exhaust gas that requires recycling at a high temperature to 200 ° C. or less with a heat exchanger or the like, resulting in a problem that the energy consumption for carbon dioxide separation increases. .
[0003]
[Problems to be solved by the invention]
The present invention seeks to provide a carbon dioxide separation method and a highly stable carbon dioxide separation membrane capable of separating and recovering carbon dioxide in exhaust gas from an energy plant or chemical plant with low energy consumption and high efficiency. To do.
[0004]
[Means for Solving the Problems]
The carbon dioxide separation method according to the present invention includes a carbon dioxide gas having a relatively high partial pressure across a region containing a composite oxide that reacts with carbon dioxide in an atmosphere of 500 ° C. or higher to produce molten lithium carbonate. A first step of flowing a second gas containing carbon dioxide gas having a relatively low partial pressure with the first gas;
The composite oxide in the region is heated to 500 ° C. or more, and the carbon dioxide gas in the first gas and the composite oxide are reacted at the contact portion between the first gas and the region, thereby melting lithium carbonate. A second step of generating
In the contact portion between the region and the second gas, molten lithium carbonate in the region is decomposed to generate carbon dioxide gas, which is discharged into the second gas from the region and is again mixed in the region. And a third step of generating
The second and third steps are repeated a plurality of times.
[0005]
Another carbon dioxide separation method according to the present invention includes a first gas containing a relatively high partial pressure carbon dioxide gas and a second gas containing a relatively low partial pressure carbon dioxide gas across the region containing lithium zirconate. A first step of flowing each of the gases,
Lithium zirconate in the region is heated to 500 ° C. or higher to cause the carbon dioxide gas in the first gas and the lithium zirconate to react with each other at the contact portion between the first gas and the region to produce molten carbonic acid. A second step of producing lithium and zirconia;
In the contact portion between the region and the second gas, the molten lithium carbonate in the region is decomposed to generate carbon dioxide gas, which is discharged from the region into the second gas, and the separated lithium is discharged into the region. And a third step of reacting with zirconia on the first gas side to produce lithium zirconate again,
The second and third steps are repeated a plurality of times.
[0006]
A carbon dioxide gas separation membrane according to the present invention comprises a separation membrane body comprising a composite oxide that reacts with carbon dioxide gas at 500 ° C. or higher to produce molten lithium carbonate, and an alkali carbonate that melts at 500 ° C. or higher;
A porous support member disposed on a side of the main body that reacts with carbon dioxide gas and a side that releases carbon dioxide gas;
It is characterized by comprising .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to FIG.
FIG. 1 is a schematic view showing a carbon dioxide gas separation membrane of the present invention. In the figure, 1 is a separation membrane body. The separation membrane body 1 is composed of an alkali carbonate mainly composed of lithium that melts at 500 ° C. or higher, for example, a mixed carbonate 2 of lithium carbonate (Li 2 CO 3 ) and potassium carbonate (K 2 CO 3 ) or a mixed carbonate thereof. A composite oxide that reacts with the carbon dioxide gas dispersed in the salt 2 to form a carbonate, for example, lithium zirconate (Li 2 ZrO 3 ) particles 3 is formed. Incidentally, the separation membrane main body 1 is the mixed zirconia carbonate 2 (ZrO 2) particles are dispersed, Li 2 is a composite oxide by reacting lithium carbonate with ZrO 2 particles of the mixed carbonate 2 ZrO 3 particles may be generated. The separation membrane main body 1 is supported from both sides by porous support members 4 and 5 made of a material stable to the mixed carbonate, for example, lithium aluminate.
[0008]
The Li 2 ZrO 3 particles preferably have a particle size of 0.4 to 1.0 μm. If the particle size of the Li 2 ZrO 3 particles is less than 0.4 μm, the stability of the particles is lowered, and there is a risk of causing mutual aggregation and particle growth. On the other hand, when the particle size of the Li 2 ZrO 3 particles exceeds 1.0 μm, the reaction area with the carbon dioxide gas becomes small, the production rate of lithium carbonate (Li 2 CO 3 ) decreases, and as a result, the carbon dioxide gas Separation performance may be reduced.
[0009]
The mixed carbonate is preferably composed of 55 to 70 mol% of lithium carbonate (Li 2 CO 3 ) and 30 to 45 mol% of potassium carbonate (K 2 CO 3 ).
The amount of the mixed carbonate is preferably 10 to 33% by weight with respect to the Li 2 ZrO 3 particles.
[0010]
The separation membrane body is produced, for example, by the following method.
First, a Li 2 ZrO 3 particle having a particle size of 0.4 to 1.0 μm is wet-mixed with, for example, 2-butanol as a solvent, dibutyl phthalate, and polyvinyl butyral as a binder to prepare a polystyrene, doctor blade method To form a porous body containing Li 2 ZrO 3 particles. Subsequently, a mixed carbonate composed of, for example, 62 mol% lithium carbonate (Li 2 CO 3 ) and 38 mol% potassium carbonate (K 2 CO 3 ) is added to the porous body in an amount of 10 to 33 wt% based on the Li 2 ZrO 3 . A separation membrane body is prepared by melt impregnation so that
[0011]
In the production of the separation membrane body, it is allowed that lithium aluminate particles coexist in the porous body.
In the production of the separation membrane body, the porous body may be formed on the porous support member by a sol-gel method or a CVD method in addition to the doctor blade method.
[0012]
Next, the carbon dioxide separation method using the carbon dioxide separation membrane described above will be described.
In the system of an oxide mainly composed of zirconium and lithium and an alkali carbonate mainly composed of lithium, for example, carbon dioxide is absorbed by the following equation (1) and carbon dioxide is released by equation (2).
[0013]
Figure 0003737574
In the temperature range of 500 to 900 ° C., the reaction of the formula (1) is particularly likely to occur under a relatively high carbon dioxide partial pressure, and the above (2) under a relatively low carbon dioxide partial pressure. The reaction of the formula is particularly likely to occur.
[0014]
In FIG. 1 described above, the porous support 4 side is the first gas 6 containing carbon dioxide gas having a relatively high partial pressure (for example, 0.7 atm), and the porous support 5 side is relatively low ( For example, the second gas 7 containing carbon dioxide of 0.2 atm) is used.
[0015]
When the separation membrane main body 1 supported from both sides by the porous supports 4 and 5 is heated to 500 ° C. or more, the contact portion with the first gas 6 having a high partial pressure of carbon dioxide gas is in the first gas 6. The carbon dioxide gas reacts with the Li 2 ZrO 3 particles 3 of the separation membrane body 1 according to the formula (1) and is absorbed as Li 2 CO 3 (liquid), and the Li 2 ZrO 3 particles are converted into ZrO 2 particles. By such a reaction, in the separation membrane body 1 in which the mixed carbonate 2 in the molten state exists, the concentration of the molten lithium carbonate at the contact portion of the first gas 6 having a high carbon dioxide partial pressure is low. The molten lithium carbonate moves from the contact portion side of the first gas 6 to the contact portion side of the second gas 7 in the mixed carbonate 2 portion in order to show a higher concentration gradient than the contact portion of the second gas 7. To do.
[0016]
Li 2 CO 3 (liquid) is decomposed in the presence of ZrO 2 (solid) in the presence of ZrO 2 (solid) at the contact portion of the separation membrane body 1 with the second gas 7 in accordance with the equation (2), and carbon dioxide gas (CO 2 ). The carbon dioxide gas is released from the separation membrane body 1 to the second gas 7 and lithium is taken in the separation membrane body 1 in the form of Li 2 ZrO 3 (solid).
[0017]
That is, when the separation membrane body 1 supported from both sides by the porous supports 4 and 5 is heated to 500 ° C. or higher, carbon dioxide gas is absorbed at the contact portion with the first gas 6 having a high partial pressure of carbon dioxide gas. Then, the concentration of molten lithium carbonate is increased, and the composite oxide particles 3 are in a form in which lithium such as zirconia (ZrO 2 ) is released. On the other hand, when carbon dioxide is released at the contact portion of the separation membrane body 1 with the second gas 7 having a low partial pressure of carbon dioxide, the concentration of molten lithium carbonate is reduced and the composite oxide particles 3 are Lithium such as Li 2 ZrO 3 is incorporated.
[0018]
Therefore, the molten lithium carbonate moves from the contact portion with the first gas 6 toward the second gas 7 due to the concentration gradient in the separation membrane body 1, that is, the contact portion with the second gas 7. In addition, the lithium is replenished so as to be responsible for the release of the carbon dioxide gas of the formula (2), while lithium is separated from the first gas 6 from the contact portion with the second gas 7 due to the concentration gradient in the separation membrane body 1. The solid phase is diffused toward the contact portion, and Li 2 ZrO 3 responsible for absorption of the carbon dioxide gas in the reaction formula (1) is generated at the contact portion with the first gas 6. In particular, since lithium has a high solid-phase diffusion rate, it is possible to rapidly supply lithium so that it is present in the form of Li 2 ZrO 3 in the contact portion of the first gas 6. The movement of molten lithium carbonate and the solid phase diffusion of lithium in such a separation membrane at 500 ° C. or higher can absorb the carbon dioxide gas in the first gas 6 and release the carbon dioxide gas into the second gas 7. The carbon dioxide gas in the first gas 6 can be separated and recovered on the second gas 7 side through the separation membrane.
[0019]
According to the present invention described above, a carbon dioxide separation method capable of separating carbon dioxide in high-temperature exhaust gas of 500 ° C. or higher, which has been difficult in the past, with high efficiency and low cost, and carbon dioxide separation with stable separation performance. A membrane can be provided.
[0020]
【Example】
Hereinafter, preferred embodiments of the present invention will be described in detail.
(Example)
First, Li 2 ZrO 3 particles having an average particle diameter of about 1.0 μm were wet-mixed with dibutyl phthalate and polyvinyl butyral for 20 hours to prepare a polystyrene, and a film having a thickness of about 10 μm was formed by a doctor blade method.
[0021]
Further, lithium aluminate particles having an average particle size of about 10 μm were wet-mixed with dibutyl phthalate and polyvinyl butyral for 20 hours to prepare a polystyrene, and a film having a thickness of about 100 μm was formed by a doctor blade method.
[0022]
Next, the Li 2 ZrO 3 particles were laminated so that the service film was sandwiched between two films containing lithium aluminate particles, heated and degreased, and then 62 mol% lithium carbonate (Li 2 CO 3 ) and potassium carbonate ( K 2 CO 3 ) Mixed carbonate consisting of 38 mol% is melt impregnated so as to be 20% by weight with respect to Li 2 ZrO 3 , and further cut into a size of 100 cm 2 to obtain the separation membrane shown in FIG. A carbon dioxide gas separation membrane in which both sides of the main body 1 were supported by porous supports 4 and 5 made of lithium aluminum aluminate was produced.
[0023]
Next, the carbon dioxide gas separation membrane 8 obtained as shown in FIG. 2 was placed in the center of the container 9 as shown in FIG. From the upper side gas inlet 12 connected to the right side surface of the vessel 9 to the upper chamber 10 at 600 ° C., 3 atm, CO 2 10% by volume, N 2 75% by volume, O 2 3% by volume, H 2 O 12% by volume. Was introduced and exhausted from the exhaust pipe 13 connected to the left side. At the same time, the lower chamber 11 was filled with 3200 cm 3 of N 2 at 600 ° C. and 0.8 atm from the lower side gas introduction rod 14 connected to the left side surface of the container 9. After maintaining such a state for 14 minutes, the gas in the lower chamber 11 was taken out from the exhaust pipe 15 and examined. As a result, CO 2 was 20% by volume and N 2 was 80% by volume at 600 ° C. and 1 atm, and 200 cm 3 of carbon dioxide gas permeation was observed in the standard state.
[0024]
Further, after a gas containing carbon dioxide having the above composition was circulated in the upper chamber 10 of the container 9 for 1000 hours, the lower chamber 11 was filled with N 2 at 0.8 atm to 3200 cm 3 . As a result, the carbon dioxide gas permeability was equivalent.
[0025]
(Comparative example)
When a cellulose acetate membrane was used instead of the separation membrane shown in FIG. 2, the gas having the above composition could not be heated to 200 ° C.
[0026]
【The invention's effect】
As described above in detail, according to the present invention, a carbon dioxide separation method capable of separating and recovering carbon dioxide in exhaust gas from an energy plant or chemical plant with low energy consumption and high efficiency and high stability. A carbon dioxide gas separation membrane can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view for explaining a carbon dioxide separation membrane and a separation method according to the present invention.
FIG. 2 is a schematic view showing a carbon dioxide separator in an embodiment of the present invention.
[Explanation of symbols]
1 ... separation membrane body,
2 ... Mixed carbonate,
3 ... lithium zirconate particles,
4, 5 ... porous support member,
6 ... first gas,
7 ... second gas,
8 ... Carbon dioxide gas separation membrane,
9: Container.

Claims (3)

５００℃以上の雰囲気下で炭酸ガスと反応して溶融炭酸リチウムを生成する複合酸化物を含む領域を挟んで相対的に高い分圧の炭酸ガスを含む第１の気体と相対的に低い分圧の炭酸ガスを含む第２の気体をそれぞれ流す第１工程と、
前記領域中の複合酸化物を５００℃以上に加熱して第１の気体と前記領域との接触部において前記第１の気体中の前記炭酸ガスと前記複合酸化物とを反応させて溶融炭酸リチウムを生成する第２工程と、
前記領域と前記第２の気体を接触部において、前記領域中の溶融炭酸リチウムを分解させて炭酸ガスを生成し、前記領域から前記第２の気体に放出すると共に前記領域中に再び複合酸化物を生成する第３工程と
を具備し、
前記第２、第３の工程を複数回繰り返すことを特徴とする炭酸ガス分離方法。 A first gas containing a relatively high partial pressure of carbon dioxide and a relatively low partial pressure across a region containing a composite oxide that reacts with carbon dioxide in an atmosphere of 500 ° C. or higher to produce molten lithium carbonate. A first step of flowing a second gas containing carbon dioxide gas,
The composite oxide in the region is heated to 500 ° C. or more, and the carbon dioxide gas in the first gas and the composite oxide are reacted at the contact portion between the first gas and the region, thereby melting lithium carbonate. A second step of generating
In the contact portion between the region and the second gas, molten lithium carbonate in the region is decomposed to generate carbon dioxide gas, which is discharged into the second gas from the region and is again mixed in the region. And a third step of generating
A carbon dioxide separation method, wherein the second and third steps are repeated a plurality of times. リチウムジルコネートを含む領域を挟んで相対的に高い分圧の炭酸ガスを含む第１の気体および相対的に低い分圧の炭酸ガスを含む第２の気体をそれぞれ流す第１工程と、前記領域中のリチウムジルコネートを５００℃以上に加熱して前記第１の気体と前記領域との接触部において前記第１の気体中の前記炭酸ガスと前記リチウムジルコネートとを反応させて溶融炭酸リチウムとジルコニアを生成する第２工程と、前記領域と前記第２の気体を接触部において、前記領域中の溶融炭酸リチウムを分解させて炭酸ガスを生成して前記領域から前記第２の気体に放出すると共に、分離されたリチウムを前記領域を拡散させて前記第１の気体側でジルコニアと反応してリチウムジルコネートを再び生成する第３工程と
を具備し、
前記第２、第３の工程とを複数回繰り返すことを特徴とする炭酸ガス分離方法。A first step of flowing a first gas containing a relatively high partial pressure carbon dioxide gas and a second gas containing a relatively low partial pressure carbon dioxide gas across the region containing lithium zirconate; The lithium zirconate therein is heated to 500 ° C. or more, and the carbon dioxide gas and the lithium zirconate in the first gas are reacted at the contact portion between the first gas and the region to obtain molten lithium carbonate. A second step of generating zirconia; and the region and the second gas are decomposed at a contact portion to decompose molten lithium carbonate in the region to generate a carbon dioxide gas, which is discharged from the region to the second gas. And a third step of diffusing the separated lithium in the region and reacting with zirconia on the first gas side to produce lithium zirconate again,
The carbon dioxide gas separation method characterized by repeating the second and third steps a plurality of times. ５００℃以上で炭酸ガスと反応して溶融炭酸リチウムを生成する複合酸化物および５００℃以上で溶融するアルカリ炭酸塩からなる分離膜本体と、
前記本体の炭酸ガスと反応する側と炭酸ガスを放出する側とにそれぞれ配置された多孔質支持部材と
を具備したことを特徴とする炭酸ガス分離膜。 A separation membrane body composed of a composite oxide that reacts with carbon dioxide at 500 ° C. or higher to produce molten lithium carbonate and an alkali carbonate that melts at 500 ° C. or higher;
Porous support members respectively disposed on a side of the main body that reacts with carbon dioxide gas and a side that releases carbon dioxide gas;
Carbon dioxide separation membrane characterized by comprising a.
JP24505796A 1996-09-17 1996-09-17 Carbon dioxide separation method and carbon dioxide separation membrane Expired - Fee Related JP3737574B2 (en)

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