JP3966934B2 - Carbon monoxide gas purification method - Google Patents
Carbon monoxide gas purification method Download PDFInfo
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- JP3966934B2 JP3966934B2 JP00468997A JP468997A JP3966934B2 JP 3966934 B2 JP3966934 B2 JP 3966934B2 JP 00468997 A JP00468997 A JP 00468997A JP 468997 A JP468997 A JP 468997A JP 3966934 B2 JP3966934 B2 JP 3966934B2
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- carbon monoxide
- monoxide gas
- sodium hydroxide
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- aqueous solution
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Description
【０００１】
【発明の属する技術分野】
本発明は一酸化炭素ガスの精製方法に関する。更に詳しくは、コークスから製造した一酸化炭素ガスを充分に精製すると同時に精製工程から排出される廃液中のＣＯＤ負荷量が低い環境にやさしい一酸化炭素ガスの精製方法に関する。
【０００２】
【従来の技術】
工業的な一酸化炭素ガスの製造法として、コークスからの製造が一般に知られている。しかしながら、コークスから製造した一酸化炭素ガス中には、コークスに含まれる硫黄分に由来するＨ2 Ｓ、ＣＯＳ、ＣＳ2 等の硫黄化合物が不純物として数ｐｐｍ〜数千ｐｐｍ含まれている。このような硫黄系不純物を含む一酸化炭素ガスを化学品の原料として使用すると、これら硫黄系不純物が大きな問題になる。例えば特開平１−２７５６３０号には、かかる硫黄系不純物を除去した一酸化炭素ガスを用いてホスゲンを製造し、このホスゲンを原料としたポリカーボネート樹脂の製造方法が開示されている。また、ガス中の硫黄系不純物の除去方法として、水酸化ナトリウム水溶液での吸収反応が一般に知られている（特公昭５９−４６５５４号）。ガス中の硫黄分の除去能力は水酸化ナトリウム水溶液の温度が高いほうが効率的である。しかしながら、一酸化炭素ガスの場合は、水酸化ナトリウム水溶液による精製中に、副反応により蟻酸が発生する。その発生量は水酸化ナトリウム水溶液の温度が高いほど多くなる。この蟻酸のＣＯＤは０．２〜０．４ｇ／ｇであり、例えば蟻酸１００ｇ／リットルのＣＯＤは２０，０００〜４０，０００ｍｇ／リットルになる。このようにＣＯＤが高い値となると、環境破壊の原因になる可能性があり問題になる。
【０００３】
【発明が解決しようとする課題】
本発明の課題は、コークスから製造した一酸化炭素ガスからＨ2 Ｓ、ＣＯＳ、ＣＳ2 等の硫黄系不純物を実質的に悪影響のない５ｐｐｍ以下程度にまで除去し、且つ工程から出る廃液中のＣＯＤ負荷量が低い環境にやさしい一酸化炭素ガスの精製方法を提供するにある。
【０００４】
本発明者は、コークスから製造した一酸化炭素ガスに水酸化ナトリウム水溶液を接触させて硫黄系不純物を除去する際に排出される廃水酸化ナトリウム水溶液中に含まれるＣＯＤ負荷原因物質である蟻酸の生成の抑制方法、及び一酸化炭素ガス中の硫黄系不純物の除去方法について鋭意検討を重ねた結果、驚くべきことに、一酸化炭素ガスと水酸化ナトリウム水溶液を接触させる際の水酸化ナトリウム水溶液の水酸化ナトリウム濃度、温度、圧力を調整することによって、一酸化炭素ガス中の硫黄系不純物が充分に除去され、同時にＣＯＤに悪影響を及ぼす蟻酸の生成を効率よく抑制し得ることを究明し、この知見に基いて更に検討を重ねた結果本発明に到達した。
【０００５】
【課題を解決するための手段】
本発明は、コークスから製造した一酸化炭素ガスに水酸化ナトリウム水溶液を接触させて一酸化炭素ガスから不純物を除去するに当り、水酸化ナトリウム水溶液の水酸化ナトリウム濃度を１〜３０重量％、水酸化ナトリウム水溶液の温度を２５〜６０℃、系内の絶対圧力を１〜５ｋｇｆ／ｃｍ２の範囲に保持することを特徴とする一酸化炭素ガスの精製方法である。
【０００６】
本発明にあっては一酸化炭素ガスと水酸化ナトリウム水溶液を接触させるに当り、水酸化ナトリウム水溶液中の水酸化ナトリウム濃度を１〜３０重量％、好ましくは５〜２０重量％、特に好ましくは５〜１５重量％にする。水酸化ナトリウム濃度が１重量％よりも低くしたり、３０重量％よりも高くすると、いずれの場合も蟻酸の生成量を低く抑制できるものの不純物の除去が充分に行なわれ難くなり、目的を達成し得ない。
【０００７】
また、水酸化ナトリウム水溶液の温度を２５〜６０℃にする。水酸化ナトリウム水溶液の温度を２５℃よりも低くすると、蟻酸の生成量を低く抑制できるものの不純物の除去が充分に行なわれ難くなり、水酸化ナトリウム水溶液の温度を６０℃よりも高くすると、蟻酸の生成量が増加し、目的を達成し得ない。
【０００８】
更に、本発明では系内の絶対圧力を１〜５ｋｇｆ／ｃｍ2 、好ましくは２〜４ｋｇｆ／ｃｍ2 にする。この圧力を１ｋｇｆ／ｃｍ2 よりも低くすると蟻酸の生成量は低く抑制することができるが、不純物が充分に除去され難く、またこの圧力を５ｋｇｆ／ｃｍ2 よりも高くすると蟻酸の生成量が増加し、目的を達し得ない。しかも圧力が１〜５ｋｇｆ／ｃｍ2 の範囲外の場合は装置が複雑になる。
【０００９】
このように、コークスから製造した一酸化炭素ガスに、特定の濃度、温度に保持した水酸化ナトリウム水溶液を特定の圧力の下に接触させることによって、一酸化炭素ガス中の硫黄系不純物の濃度を５ｐｐｍ以下にし、且つ廃液中のＣＯＤ負荷原因物質の一つである蟻酸濃度を６０ｇ／リットル以下にすることを可能にしたものであり、これら三つの条件のいずれか一つを欠いてもかかる効果は達成されない。
【００１０】
本発明の方法を実施するに使用する装置には気・液接触用装置が任意に採用され、例えば交流接触型ガス吸収塔等が好ましい。
【００１１】
【発明の実施の形態】
以下、実施例及び比較例により本発明を更に詳しく説明する。なお、ガス中硫黄分濃度の分析及び廃アルカリ水溶液中の蟻酸濃度の測定はガスクロマトグラフィーを用いて行い、検出限界以下（０．１ｐｐｍ）のものをＮＤとした。
【００１２】
［実施例１］
本実施例では交流接触型ガス吸収塔を用いて一酸化炭素ガスの精製を行った。充填材にテラレットを用い、一酸化炭素ガスの硫黄含有量は、Ｈ2 Ｓが１，５００ｐｐｍ、ＣＯＳが１５ｐｐｍ、ＣＳ2 が５ｐｐｍであった。一酸化炭素ガスの流量は１００リットル・Ｎ／分、系内の圧力は３．０ｋｇｆ／ｃｍ2 （絶対圧）、水酸化ナトリウム水溶液中の水酸化ナトリウム濃度は１０重量％、水酸化ナトリウム水溶液の温度は５５℃、各塔での水酸化ナトリウム水溶液の循環量は１５リットル／分、水酸化ナトリウム水溶液の抜取り量は５０ｍｌ／分とした。得られた結果を表１に示す。
【００１３】
［実施例２］
水酸化ナトリウム水溶液の温度を４０℃にする以外は実施例１と同様の条件で一酸化炭素ガスの精製を行った。得られた結果を表１に示す。
【００１４】
［実施例３］
水酸化ナトリウム水溶液の温度を３０℃にする以外は実施例１と同様の条件で一酸化炭素ガスの精製を行った。得られた結果を表１に示す。
【００１５】
［実施例４］
系内の圧力を１．５ｋｇｆ／ｃｍ2 （絶対圧）にする以外は実施例１と同様の条件で一酸化炭素ガスの精製を行った。得られた結果を表１に示す。
【００１６】
［比較例１］
水酸化ナトリウム水溶液の温度を７５℃にする以外は実施例１と同様の条件で一酸化炭素ガスの精製を行った。得られた結果を表１に示す。
【００１７】
［比較例２］
水酸化ナトリウム水溶液の温度を５℃にする以外は実施例１と同様の条件で一酸化炭素ガスの精製を行った。得られた結果を表１に示す。
【００１８】
［比較例３］
水酸化ナトリウム水溶液中の水酸化ナトリウム濃度を０．５重量％にする以外は実施例１と同様の条件で一酸化炭素ガスの精製を行った。得られた結果を表１に示す。
【００１９】
［比較例４］
水酸化ナトリウム水溶液中の水酸化ナトリウム濃度を４０重量％にする以外は実施例１と同様の条件で一酸化炭素ガスの精製を行った。得られた結果を表１に示す。
【００２０】
［比較例５］
系内の圧力をを７．０ｋｇｆ／ｃｍ2 にする以外は実施例１と同様の条件で一酸化炭素ガスの精製を行った。得られた結果を表１に示す。
【００２１】
【表１】
【発明の効果】
本発明によれば、コークスから製造した一酸化炭素ガス中の硫黄系不純物を極めて容易に且つ充分（５ｐｐｍ以下）に除去することができ、しかも廃液中の蟻酸濃度を６０ｇ／リットル以下とＣＯＤ負荷量を充分に低くし、環境にやさしいプロセスの提供が可能になり、その奏する工業的効果は格別なものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for purifying carbon monoxide gas. More specifically, the present invention relates to a method for refining carbon monoxide gas that is sufficiently environmentally friendly and sufficiently purifies carbon monoxide gas produced from coke and at the same time has a low COD load in the waste liquid discharged from the refining process.
[0002]
[Prior art]
As an industrial method for producing carbon monoxide gas, production from coke is generally known. However, the carbon monoxide gas produced from coke contains several ppm to several thousand ppm of sulfur compounds such as H 2 S, COS, and CS 2 derived from sulfur contained in the coke as impurities. When carbon monoxide gas containing such sulfur-based impurities is used as a raw material for chemical products, these sulfur-based impurities become a big problem. For example, Japanese Patent Application Laid-Open No. 1-275630 discloses a method for producing a polycarbonate resin by producing phosgene using carbon monoxide gas from which such sulfur impurities have been removed, and using the phosgene as a raw material. As a method for removing sulfur-based impurities in gas, an absorption reaction with an aqueous sodium hydroxide solution is generally known (Japanese Patent Publication No. 59-46554). The ability to remove sulfur in the gas is more efficient when the temperature of the aqueous sodium hydroxide solution is higher. However, in the case of carbon monoxide gas, formic acid is generated by a side reaction during purification with an aqueous sodium hydroxide solution. The amount generated increases as the temperature of the aqueous sodium hydroxide solution increases. The COD of this formic acid is 0.2 to 0.4 g / g. For example, the COD of formic acid 100 g / liter is 20,000 to 40,000 mg / liter. Thus, when COD becomes a high value, it may become a cause of environmental destruction, and becomes a problem.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to remove sulfur-based impurities such as H 2 S, COS, and CS 2 from carbon monoxide gas produced from coke to about 5 ppm or less with substantially no adverse effect, and in the waste liquid discharged from the process. An object of the present invention is to provide an environment-friendly carbon monoxide gas purification method having a low COD load.
[0004]
The present inventor has produced formic acid that is a COD load causative substance contained in a waste sodium hydroxide aqueous solution discharged when a sodium hydroxide aqueous solution is brought into contact with carbon monoxide gas produced from coke to remove sulfur impurities. As a result of intensive investigations on the method of suppressing carbon and the removal of sulfur-based impurities in carbon monoxide gas, surprisingly, as a result, the water of the sodium hydroxide aqueous solution when contacting the carbon monoxide gas and the sodium hydroxide aqueous solution By adjusting sodium oxide concentration, temperature, and pressure, it was found that sulfur-based impurities in carbon monoxide gas can be sufficiently removed, and at the same time, the production of formic acid that adversely affects COD can be efficiently suppressed. As a result of further investigation based on this, the present invention has been reached.
[0005]
[Means for Solving the Problems]
In the present invention, when removing an impurity from a carbon monoxide gas by contacting a carbon monoxide gas produced from coke with a sodium hydroxide aqueous solution, the sodium hydroxide concentration of the sodium hydroxide aqueous solution is 1 to 30% by weight, A method for purifying carbon monoxide gas, characterized in that the temperature of an aqueous sodium oxide solution is 25 to 60 ° C. and the absolute pressure in the system is maintained in the range of 1 to 5 kgf / cm 2 .
[0006]
In the present invention, when contacting the carbon monoxide gas and the aqueous sodium hydroxide solution, the sodium hydroxide concentration in the aqueous sodium hydroxide solution is 1 to 30% by weight, preferably 5 to 20% by weight, particularly preferably 5%. ˜15 wt%. When the sodium hydroxide concentration is lower than 1% by weight or higher than 30% by weight, in any case, the amount of formic acid produced can be suppressed to a low level, but it is difficult to remove impurities sufficiently and the object is achieved. I don't get it.
[0007]
Further, the temperature of the sodium hydroxide aqueous solution is set to 25 to 60 ° C. If the temperature of the sodium hydroxide aqueous solution is lower than 25 ° C. , the amount of formic acid produced can be suppressed to a low level, but it is difficult to remove impurities sufficiently. If the temperature of the sodium hydroxide aqueous solution is higher than 60 ° C. , the formic acid The production amount increases and the objective cannot be achieved.
[0008]
Furthermore, in the present invention, the absolute pressure in the system is 1 to 5 kgf / cm 2 , preferably 2 to 4 kgf / cm 2 . If this pressure is lower than 1 kgf / cm 2, the amount of formic acid produced can be suppressed to a low level, but impurities are not sufficiently removed, and if this pressure is higher than 5 kgf / cm 2, the amount of formic acid produced increases. However, the purpose cannot be achieved. Moreover, when the pressure is outside the range of 1 to 5 kgf / cm 2 , the apparatus becomes complicated.
[0009]
In this way, the concentration of sulfur-based impurities in the carbon monoxide gas can be reduced by bringing the aqueous solution of sodium hydroxide maintained at a specific concentration and temperature into contact with the carbon monoxide gas produced from coke under a specific pressure. This makes it possible to reduce the formic acid concentration, which is one of the COD load-causing substances in the waste liquid, to 60 g / liter or less, and this effect is obtained even if any one of these three conditions is missing. Is not achieved.
[0010]
The apparatus used for carrying out the method of the present invention arbitrarily adopts a gas / liquid contact apparatus, and for example, an AC contact type gas absorption tower is preferable.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The analysis of the sulfur concentration in the gas and the measurement of the formic acid concentration in the waste alkaline aqueous solution were performed using gas chromatography, and ND below the detection limit (0.1 ppm) was determined.
[0012]
[Example 1]
In this example, carbon monoxide gas was purified using an AC contact gas absorption tower. Terralet was used as the filler, and the sulfur content of the carbon monoxide gas was 1,500 ppm for H 2 S, 15 ppm for COS, and 5 ppm for CS 2 . The flow rate of carbon monoxide gas is 100 liters / N / min, the pressure in the system is 3.0 kgf / cm 2 (absolute pressure), the concentration of sodium hydroxide in the aqueous sodium hydroxide solution is 10% by weight, The temperature was 55 ° C., the circulation amount of the sodium hydroxide aqueous solution in each tower was 15 liters / minute, and the extraction amount of the sodium hydroxide aqueous solution was 50 ml / minute. The obtained results are shown in Table 1.
[0013]
[Example 2]
Carbon monoxide gas was purified under the same conditions as in Example 1 except that the temperature of the aqueous sodium hydroxide solution was 40 ° C. The obtained results are shown in Table 1.
[0014]
[Example 3]
Carbon monoxide gas was purified under the same conditions as in Example 1 except that the temperature of the aqueous sodium hydroxide solution was 30 ° C. The obtained results are shown in Table 1.
[0015]
[Example 4]
Carbon monoxide gas was purified under the same conditions as in Example 1 except that the pressure in the system was 1.5 kgf / cm 2 (absolute pressure). The obtained results are shown in Table 1.
[0016]
[Comparative Example 1]
Carbon monoxide gas was purified under the same conditions as in Example 1 except that the temperature of the aqueous sodium hydroxide solution was 75 ° C. The obtained results are shown in Table 1.
[0017]
[Comparative Example 2]
Carbon monoxide gas was purified under the same conditions as in Example 1 except that the temperature of the aqueous sodium hydroxide solution was 5 ° C. The obtained results are shown in Table 1.
[0018]
[Comparative Example 3]
Carbon monoxide gas was purified under the same conditions as in Example 1 except that the sodium hydroxide concentration in the aqueous sodium hydroxide solution was 0.5 wt%. The obtained results are shown in Table 1.
[0019]
[Comparative Example 4]
Carbon monoxide gas was purified under the same conditions as in Example 1 except that the sodium hydroxide concentration in the aqueous sodium hydroxide solution was 40% by weight. The obtained results are shown in Table 1.
[0020]
[Comparative Example 5]
Carbon monoxide gas was purified under the same conditions as in Example 1 except that the pressure in the system was 7.0 kgf / cm 2 . The obtained results are shown in Table 1.
[0021]
[Table 1]
【The invention's effect】
According to the present invention, sulfur-based impurities in carbon monoxide gas produced from coke can be removed very easily and sufficiently (5 ppm or less), and the formic acid concentration in the waste liquid is 60 g / liter or less and COD load. The amount can be made sufficiently low to provide an environmentally friendly process, and its industrial effect is exceptional.
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00468997A JP3966934B2 (en) | 1997-01-14 | 1997-01-14 | Carbon monoxide gas purification method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00468997A JP3966934B2 (en) | 1997-01-14 | 1997-01-14 | Carbon monoxide gas purification method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10194716A JPH10194716A (en) | 1998-07-28 |
| JP3966934B2 true JP3966934B2 (en) | 2007-08-29 |
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| JP00468997A Expired - Fee Related JP3966934B2 (en) | 1997-01-14 | 1997-01-14 | Carbon monoxide gas purification method |
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| CN1079820C (en) * | 1998-11-23 | 2002-02-27 | 烟台万华聚氨酯股份有限公司 | Desulfurizing process |
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| JPH10194716A (en) | 1998-07-28 |
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