JP2006150308A - Nitrogen oxide absorbent - Google Patents
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Abstract
Description
本発明は、窒素酸化物の吸収効率を向上させた窒素酸化物吸収剤に関するものである。 The present invention relates to a nitrogen oxide absorbent with improved nitrogen oxide absorption efficiency.
道路トンネル等の換気ガスは一酸化窒素（ＮＯ）、二酸化窒素（ＮＯ2）を主とする低濃度のＮＯｘ（窒素酸化物）を含んでいる。これらのＮＯｘを除去して換気ガスを浄化する方法としては、ＮＯｘを吸着剤により吸着除去する方式が知られている（下記、特許文献１，２を参照。）。
Ventilation gases such as road tunnels contain low concentrations of NOx (nitrogen oxides), mainly nitrogen monoxide (NO) and nitrogen dioxide (NO 2 ). As a method of purifying the ventilation gas by removing these NOx, a method of adsorbing and removing NOx with an adsorbent is known (see
また、活性炭、水酸化カルシウム及び石膏からなるハニカム状の担体に水酸化カリウム（窒素酸化物吸収物質）水溶液を含浸させた、道路トンネル換気ガスのＮＯｘ吸収剤が知られている（下記、特許文献３，４を参照。）。この吸収剤は、アルカリとの反応（化学吸収）によりＮＯｘを除去するため、ＮＯｘの吸収容量が大きく、無再生で長時間使用できるなどの利点を有する。 Further, a NOx absorbent for road tunnel ventilation gas is known in which a honeycomb-shaped carrier made of activated carbon, calcium hydroxide and gypsum is impregnated with an aqueous solution of potassium hydroxide (nitrogen oxide absorbent) (see Patent Documents below). (See 3, 4). Since this absorbent removes NOx by reaction with alkali (chemical absorption), it has an advantage that it has a large NOx absorption capacity and can be used for a long time without regeneration.
しかしながら、化学吸収によらない吸着作用を利用した吸着方式の場合、吸着したＮＯｘがわずかな温度変化により脱着して再び飛散するおそれがあり、確実なＮＯｘ除去方法とは言えない。 However, in the case of an adsorption method using an adsorption action not based on chemical absorption, the adsorbed NOx may be desorbed due to a slight temperature change and scattered again, which is not a reliable NOx removal method.
また、化学吸収によるＮＯｘ除去の場合、水酸化カリウムなどのアルカリ成分（窒素酸化物吸収物質）とＮＯｘとの化学反応速度が遅いため、ＮＯｘ吸収効率が十分ではない。例えば、アルカリ成分の利用率が低い段階、すなわち未反応のアルカリ成分が存在するにもかかわらず所定の除去性能が得られなくなるなどの問題がある。 Further, in the case of NOx removal by chemical absorption, the NOx absorption efficiency is not sufficient because the chemical reaction rate between an alkaline component (nitrogen oxide absorbing material) such as potassium hydroxide and NOx is slow. For example, there is a problem that a predetermined removal performance cannot be obtained even when the utilization rate of the alkali component is low, that is, an unreacted alkali component is present.
このため、短期間での吸収剤の交換作業や再生作業が必要となったり、予め過剰の吸収剤を設置しておく必要があり、前者の場合には交換や再生に要する費用が多くなり、後者の場合には設備費用が多くなるといった問題がある。また、トンネル内などに設けられたＮＯｘ浄化設備用のスペースは、吸収剤を更に増設することができるほどの余裕がない場合が多く、このような状況では、交換回数を増やすなどが主たる対応策となっているのが現状である。 For this reason, it is necessary to replace and regenerate the absorbent in a short period of time, or it is necessary to install an excessive amount of absorbent in advance. In the former case, the cost required for replacement and regeneration increases. In the latter case, there is a problem that the equipment cost increases. In addition, the space for NOx purification equipment provided in tunnels and the like often does not have enough room for additional absorbent, and in such situations, the main countermeasure is to increase the number of replacements. This is the current situation.
本発明は、上記状況に鑑みてなされたものであり、窒素酸化物の吸収効率を向上させた窒素酸化物吸収剤を提供することを目的とする。 This invention is made | formed in view of the said condition, and it aims at providing the nitrogen oxide absorber which improved the absorption efficiency of nitrogen oxide.
上記課題を解決するため、本発明者らは鋭意研究を進めた結果、例えばヨウ化カリウム、鉄（II）の塩又はスズ（II）の塩などのＮＯｘイオン化剤を添加することにより、アルカリ成分とＮＯｘとの化学反応速度が高まり、ＮＯｘ吸収効率が向上することを見出した。 In order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, by adding a NOx ionizing agent such as potassium iodide, iron (II) salt or tin (II) salt, an alkaline component It has been found that the chemical reaction rate between NOx and NOx is increased, and the NOx absorption efficiency is improved.
上記課題を解決する本発明に係る窒素酸化物吸収剤は、
担体にアルカリ金属の水酸化物、酸化物又は炭酸塩のうち少なくとも１つの窒素酸化物吸収物質を担持させてなる窒素酸化物吸収剤において、
前記担体に、更に、窒素酸化物をイオン化するイオン化剤を担持させたことを特徴とする窒素酸化物吸収剤である。
The nitrogen oxide absorbent according to the present invention for solving the above problems is
In the nitrogen oxide absorbent formed by supporting at least one nitrogen oxide absorbing material of alkali metal hydroxide, oxide or carbonate on the carrier,
A nitrogen oxide absorbent characterized in that an ionizing agent that ionizes nitrogen oxide is further supported on the carrier.
また、上記窒素酸化物吸収剤において、
前記イオン化剤は、ヨウ化カリウム、鉄（II）の塩又はスズ（II）の塩のうち少なくとも１つであることを特徴とする窒素酸化物吸収剤である。
In the nitrogen oxide absorbent,
The ionizing agent is at least one of potassium iodide, iron (II) salt or tin (II) salt, and is a nitrogen oxide absorbent.
また、上記窒素酸化物吸収剤において、
前記担体は、活性炭であることを特徴とする窒素酸化物吸収剤である。
In the nitrogen oxide absorbent,
The carrier is a nitrogen oxide absorbent characterized by being activated carbon.
また、上記窒素酸化物吸収剤において、
前記担体は、カルシウム又はアルミニウムの水酸化物、酸化物、炭酸塩又は硫酸塩のうち少なくとも１つを含有することを特徴とする窒素酸化物吸収剤である。
In the nitrogen oxide absorbent,
The carrier is a nitrogen oxide absorbent characterized by containing at least one of a hydroxide, oxide, carbonate or sulfate of calcium or aluminum.
また、上記窒素酸化物吸収剤において、
前記イオン化剤は、窒素酸化物吸収剤全体に対して１〜２０重量％であることを特徴とする窒素酸化物吸収剤である。
In the nitrogen oxide absorbent,
The ionizing agent is a nitrogen oxide absorbent characterized in that the ionizing agent is 1 to 20% by weight with respect to the whole nitrogen oxide absorbent.
また、上記窒素酸化物吸収剤において、
前記窒素酸化物吸収物質は窒素酸化物吸収剤全体に対して３〜４０重量％であり、前記活性炭は窒素酸化物吸収剤全体に対して２０〜９５重量％であることを特徴とする窒素酸化物吸収剤である。
In the nitrogen oxide absorbent,
The nitrogen oxide absorbing material is 3 to 40% by weight with respect to the whole nitrogen oxide absorbent, and the activated carbon is 20 to 95% by weight with respect to the whole nitrogen oxide absorbent. It is a material absorbent.
また、上記窒素酸化物吸収剤において、
前記窒素酸化物吸収物質は窒素酸化物吸収剤全体に対して３〜４０重量％であり、前記カルシウム又はアルミニウムの水酸化物、酸化物、炭酸塩又は硫酸塩のうち少なくとも１つは窒素酸化物吸収剤全体に対して３０〜８０重量％であることを特徴とする窒素酸化物吸収剤である。
In the nitrogen oxide absorbent,
The nitrogen oxide absorbing material is 3 to 40% by weight based on the whole nitrogen oxide absorbent, and at least one of the calcium or aluminum hydroxide, oxide, carbonate or sulfate is nitrogen oxide. It is a nitrogen oxide absorbent characterized by being 30 to 80% by weight based on the whole absorbent.
また、上記窒素酸化物吸収剤において、
前記担体の形状は、ハニカム形状、コルゲート形状、粉体、ペレット形状、繊維状又はシート形状のいずれかであることを特徴とする窒素酸化物吸収剤である。
In the nitrogen oxide absorbent,
The shape of the carrier is a nitrogen oxide absorbent characterized in that it is any one of a honeycomb shape, a corrugated shape, a powder, a pellet shape, a fiber shape, and a sheet shape.
本発明にかかる窒素酸化物吸収剤によれば、例えばヨウ化カリウム、鉄（II）の塩又はスズ（II）の塩などのＮＯｘイオン化剤を添加することにより、ＮＯｘ、特にＮＯ2をイオン化させてＮＯｘ吸収物質への吸収効率を向上させることができる。この結果、ＮＯｘ吸収物質の利用率を向上させることができ、短期間での吸収剤の交換作業や再生作業を不要としたり、予め過剰の吸収剤を設置しておく必要をなくしたりすることができる。 According to the nitrogen oxide absorbent according to the present invention, NOx, particularly NO 2, is ionized by adding a NOx ionizing agent such as potassium iodide, iron (II) salt or tin (II) salt. Thus, the absorption efficiency into the NOx absorbing material can be improved. As a result, the utilization rate of the NOx absorbent can be improved, and it is possible to eliminate the need to replace or regenerate the absorbent in a short period of time, or eliminate the need to install an excessive absorbent in advance. it can.
上述するように、トンネル内などに設けられたＮＯｘ浄化設備用のスペースは、吸収剤を更に増設することができるほどの余裕がない場合が多く、本発明によりＮＯｘ吸収効率を向上させることができることは、このような設備に対して極めて有用である。 As described above, the space for the NOx purification facility provided in the tunnel or the like often does not have enough room for additional absorbent, and the present invention can improve the NOx absorption efficiency. Is extremely useful for such equipment.
また、担体を主として活性炭から構成することにより、活性炭の有する大きな比表面積を利用して、ＮＯｘ吸収性能を向上させることができる。また、ＮＯｘ吸収剤を低コストで製造することができるため、使い捨ての吸収剤とすることができる。また、使い捨ての利用方法とすれば、担体に対して再生作業に伴う強度を付与する必要がないため、活性炭で形成した耐久性で十分となる。 Further, by constituting the carrier mainly from activated carbon, the NOx absorption performance can be improved by utilizing the large specific surface area of the activated carbon. Further, since the NOx absorbent can be manufactured at a low cost, it can be a disposable absorbent. Moreover, if it is set as a disposable utilization method, since it is not necessary to provide the intensity | strength accompanying a reproduction | regeneration operation | work with respect to a support | carrier, the durability formed with activated carbon will be enough.
さらに、担体にカルシウム又はアルミニウムの水酸化物、酸化物、炭酸塩又は硫酸塩のうち少なくとも１つを含有させることにより、担体の耐久性を向上させることができる。窒素酸化物吸収剤は、再生して再び使用することができるが、担体部分が脆いと再生作業において形状が崩れてしまい、ＮＯｘ吸収物質が再生可能であっても、吸収剤として再び製造しなおさなければならない。すなわち、担体の耐久性を向上させることは、吸収剤の再生回数の向上を意味し、換気ガスの浄化コストの低減に繋がる。 Furthermore, the durability of the carrier can be improved by containing at least one of calcium, aluminum hydroxide, oxide, carbonate or sulfate in the carrier. Nitrogen oxide absorbents can be regenerated and reused, but if the carrier part is brittle, the shape will be lost in the regeneration process, and even if the NOx absorbent is recyclable, it must be remanufactured as an absorbent. There must be. That is, improving the durability of the carrier means an improvement in the number of times the absorbent is regenerated, leading to a reduction in the purification cost of the ventilation gas.
以下、図面に基づいて本発明の実施例を詳細に説明する。図１は、本発明の実施例１に係るＮＯｘ吸収剤のＮＯｘ吸収性能を示すグラフである。図２は、本発明の実施例２に係るＮＯｘ吸収剤のＮＯｘ吸収性能を示すグラフである。また、図３は、本発明の実施例と比較例に係るＮＯｘ吸収剤の構成とＮＯｘ浄化性能をまとめた表である。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a graph showing the NOx absorption performance of the NOx absorbent according to Example 1 of the present invention. FIG. 2 is a graph showing the NOx absorption performance of the NOx absorbent according to Example 2 of the present invention. FIG. 3 is a table summarizing the configurations of NOx absorbents and NOx purification performance according to examples and comparative examples of the present invention.
＜第１の実施例＞
実施例１に係るＮＯｘ吸収剤及び比較例１に係るＮＯｘ吸収剤共に、活性炭のみで形成したハニカム形状の担体に、ＮＯｘ吸収物質として水酸化カリウム（ＫＯＨ）を担持させた。実施例１に係る吸収剤には、更に、ＮＯｘのイオン化剤としてヨウ化カリウム（ＫＩ）を担持させた。
<First embodiment>
In both the NOx absorbent according to Example 1 and the NOx absorbent according to Comparative Example 1, potassium hydroxide (KOH) was supported as a NOx absorbent on a honeycomb-shaped carrier formed only of activated carbon. The absorbent according to Example 1 was further loaded with potassium iodide (KI) as an ionizing agent for NOx.
詳細な製造方法は以下のとおりである。まず、活性炭をハニカム形状に形成して担体を作製する。次に、所定濃度の水酸化カリウム水溶液の中にこの担体を沈めて、担体に水酸化カリウムを含浸させる。次に、これを乾燥させた。この結果、図３に示すように、活性炭９１重量％と活性炭に含浸させた水酸化カリウム９重量％の組成からなるＮＯｘ吸収剤（比較例１）を作製した。 The detailed manufacturing method is as follows. First, activated carbon is formed in a honeycomb shape to produce a carrier. Next, the carrier is submerged in an aqueous potassium hydroxide solution having a predetermined concentration, and the carrier is impregnated with potassium hydroxide. This was then dried. As a result, as shown in FIG. 3, a NOx absorbent (Comparative Example 1) having a composition of 91% by weight of activated carbon and 9% by weight of potassium hydroxide impregnated in the activated carbon was produced.
比較例１の製造方法と同様に作製したＮＯｘ吸収剤を、更に、所定濃度のヨウ化カリウム水溶液の中に沈めて、担体にヨウ化カリウムを含浸させる。次に、これを乾燥させた。この結果、図３に示すように、活性炭８１重量％と活性炭に含浸させた水酸化カリウム９重量％、ヨウ化カリウム１０重量％の組成からなるＮＯｘ吸収剤（実施例１）を作製した。なお、実施例１に係るＮＯｘ吸収剤の製造方法としては、活性炭の担体を水酸化カリウムとヨウ化カリウムの混合水溶液中に沈めて含浸させてもよい。 The NOx absorbent prepared in the same manner as in the production method of Comparative Example 1 is further submerged in a potassium iodide aqueous solution having a predetermined concentration, and the support is impregnated with potassium iodide. This was then dried. As a result, as shown in FIG. 3, a NOx absorbent (Example 1) having a composition of 81% by weight of activated carbon, 9% by weight of potassium hydroxide impregnated in the activated carbon, and 10% by weight of potassium iodide was prepared. In addition, as a manufacturing method of the NOx absorbent according to Example 1, an activated carbon carrier may be submerged in a mixed aqueous solution of potassium hydroxide and potassium iodide.
次に、実施例１及び比較例１に係るＮＯｘ吸収剤のＮＯｘ浄化性能について試験した。試験方法としては、体積５ｍｌのＮＯｘ吸収剤に、温度２０℃、相対湿度６０％、ＮＯ2濃度１０ｐｐｍの空気を、空塔速度ＳＶ（＝通ガス流量(ｍ3／ｈ)／吸収剤容量(ｍ3)）27000ｈ-1で通過させて、ＮＯｘ浄化性能を試験した。 Next, the NOx purification performance of the NOx absorbent according to Example 1 and Comparative Example 1 was tested. As a test method, a NOx absorbent having a volume of 5 ml, an air having a temperature of 20 ° C., a relative humidity of 60%, and a NO 2 concentration of 10 ppm were used, and the superficial velocity SV (= gas flow rate (m 3 / h) / absorbent capacity ( m 3 )) Passed at 27000 h −1 to test NOx purification performance.
図１は、ＮＯｘ浄化性能の試験結果を示すグラフである。同図に示すように、比較例１よりも実施例１に係るＮＯｘ吸収剤の方が、高いＮＯ2除去率が長時間にわたって維持されていることが分かる。図３にＮＯｘ除去性能をまとめて示すように、実施例１に係るＮＯｘ吸収剤は、初期（例えば、通ガス時間１時間）のＮＯ2除去率は９８％であり、ＮＯ2除去率９０％以上を維持する時間が７０時間であった。また、ＮＯ2除去率が９０％以上を維持できなくなった時点におけるＫＯＨ利用率は４６％であった。 FIG. 1 is a graph showing the test results of NOx purification performance. As shown in the figure, it can be seen that the NOx absorbent according to Example 1 maintains a higher NO 2 removal rate over a longer time than Comparative Example 1. As shown collectively NOx removal performance in Figure 3, NOx absorbent according to Example 1, the initial (e.g., passing the gas over 1 hour) NO 2 removal rate is 98%, NO 2 removal of 90% The time for maintaining the above was 70 hours. Moreover, the KOH utilization rate at the time when the NO 2 removal rate could not maintain 90% or more was 46%.
これに対して、比較例１に係るＮＯｘ吸収剤は、初期（例えば、通ガス時間１時間）のＮＯ2除去率は９１％であり、ＮＯ2除去率９０%以上を維持する時間が１８時間であった。また、ＮＯ2除去率が９０％以上を維持できなくなった時点におけるＫＯＨ利用率は１２％であった。
In contrast, NOx absorbent of Comparative Example 1, the initial (e.g., passing the gas over 1 hour) NO 2 removal rate is 91%, the time to maintain more than 90% NO 2
すなわち、実施例１に係るＮＯｘ吸収剤は、比較例１に係るＮＯｘ吸収剤に比べて、高いＮＯｘ除去率を長時間にわたって維持すると共に、ＫＯＨ利用率が高く、ＮＯｘ吸収物質を有効に活用している吸収剤であることが分かる。 That is, the NOx absorbent according to Example 1 maintains a high NOx removal rate for a long time as compared with the NOx absorbent according to Comparative Example 1, and has a high KOH utilization rate, and effectively utilizes the NOx absorbent. It turns out that it is an absorbent.
ＮＯｘ吸収剤のＮＯｘ吸収作用は、下記式（１）で説明することができる。
２ＮＯ2＋２ＫＯＨ→ＫＮＯ2＋ＫＮＯ3＋Ｈ2Ｏ ・・・（１）
すなわち、流通ガス中のＮＯ2がＮＯｘ吸収物質である水酸化カリウムと化学反応を起こして、カリウムの硝酸塩となることにより、流通ガス中のＮＯｘがＮＯｘ吸収剤に化学吸収される。しかしながら、この化学吸収反応は反応速度が比較的遅いため、ＮＯｘ吸収物質のみでは、比較例１に係るＮＯｘ吸収剤のように、ＮＯｘ吸収性能は十分ではない。
The NOx absorption action of the NOx absorbent can be explained by the following formula (1).
2NO 2 + 2KOH → KNO 2 + KNO 3 + H 2 O (1)
That is, NO 2 in the circulating gas undergoes a chemical reaction with potassium hydroxide, which is a NOx absorbing material, to become potassium nitrate, whereby NOx in the circulating gas is chemically absorbed by the NOx absorbent. However, since this chemical absorption reaction has a relatively slow reaction rate, the NOx absorbing material alone is not sufficient in the NOx absorbing performance like the NOx absorbent according to Comparative Example 1.
これに対して、実施例１に係るＮＯｘ吸収剤には、ＮＯｘ吸収物質である水酸化カリウムに加えて、ＮＯｘのイオン化剤であるヨウ化カリウムが担持されており、下記式（２）、（３）により流通ガス中のＮＯｘがＩ-の還元作用によりイオン化されると考えられる。
ＫＩ→Ｉ-＋Ｋ- ・・・（２）
２Ｉ-＋２ＮＯ2→２ＮＯ2 -＋Ｉ2・・・（３）
On the other hand, the NOx absorbent according to Example 1 carries potassium iodide, which is an ionizing agent for NOx, in addition to potassium hydroxide, which is a NOx absorbent, and has the following formulas (2), ( According to 3), NOx in the flowing gas is considered to be ionized by the reducing action of I − .
KI → I − + K − (2)
2I − + 2NO 2 → 2NO 2 − + I 2 (3)
このようにして生成したイオン化されたＮＯｘは、水酸化カリウムとの反応性、未利用領域の水酸化カリウムへの浸透性に富むと考えられる。この結果、実施例１に係るＮＯｘ吸収剤は、ＮＯｘ除去効率の向上、ＮＯｘ吸収物質の利用率の向上を達成したものと考えられる。 The ionized NOx produced in this way is considered to be rich in reactivity with potassium hydroxide and permeability to potassium hydroxide in unused areas. As a result, it is considered that the NOx absorbent according to Example 1 achieved an improvement in NOx removal efficiency and an improvement in the utilization rate of the NOx absorbent.
なお、上記式（３）により生成したＩ2は、排気ガス中や活性炭などに存在するＳＯ2などの還元作用によりＩ-に還元され、再び上記式（３）に関与するものと考えられる。 It is considered that I 2 generated by the above formula (3) is reduced to I − by the reducing action of SO 2 or the like present in the exhaust gas or activated carbon, and again participates in the above formula (3).
＜第２の実施例＞
実施例２に係るＮＯｘ吸収剤及び比較例２に係るＮＯｘ吸収剤共に、活性炭及び水酸化カルシウム（Ｃａ(ＯＨ)2）、硫酸カルシウム（ＣａＳＯ4）で形成したハニカム形状の担体に、ＮＯｘ吸収物質として水酸化カリウム（ＫＯＨ）を担持させた。実施例２に係る吸収剤には、更に、ＮＯｘのイオン化剤としてヨウ化カリウム（ＫＩ）を担持させた。
<Second embodiment>
The NOx absorbent according to Example 2 and the NOx absorbent according to Comparative Example 2 are both formed on a honeycomb-shaped carrier formed of activated carbon, calcium hydroxide (Ca (OH) 2 ), and calcium sulfate (CaSO 4 ). As potassium hydroxide (KOH). The absorbent according to Example 2 was further loaded with potassium iodide (KI) as an ionizing agent for NOx.
詳細な製造方法は以下のとおりである。まず、活性炭及び水酸化カルシウム、硫酸カルシウムの所定組成比の混合物をハニカム形状に形成して担体を作製する。次に、所定濃度の水酸化カリウム水溶液の中にこの担体を沈めて、担体に水酸化カリウムを含浸させる。次に、これを乾燥させた。この結果、図３に示すように、活性炭２７重量％と水酸化カルシウム４７重量％、硫酸カルシウム８重量％と、これらに含浸させた水酸化カリウム１８重量％の組成からなるＮＯｘ吸収剤（比較例２）を作製した。 The detailed manufacturing method is as follows. First, a support is prepared by forming a mixture of activated carbon, calcium hydroxide, and calcium sulfate with a predetermined composition ratio into a honeycomb shape. Next, the carrier is submerged in an aqueous potassium hydroxide solution having a predetermined concentration, and the carrier is impregnated with potassium hydroxide. This was then dried. As a result, as shown in FIG. 3, a NOx absorbent comprising a composition of 27% by weight of activated carbon, 47% by weight of calcium hydroxide, 8% by weight of calcium sulfate, and 18% by weight of potassium hydroxide impregnated therein (comparative example) 2) was produced.
比較例２の製造方法と同様に作製したＮＯｘ吸収剤を、更に、所定濃度のヨウ化カリウム水溶液の中に沈めて、担体にヨウ化カリウムを含浸させる。次に、これを乾燥させた。この結果、図３に示すように、活性炭２５重量％と水酸化カルシウム４５重量％、硫酸カルシウム７重量％と、これらに含浸させた水酸化カリウム１８重量％、ヨウ化カリウム５重量％の組成からなるＮＯｘ吸収剤（実施例２）を作製した。なお、実施例２に係るＮＯｘ吸収剤の製造方法としては、活性炭の担体を水酸化カリウムとヨウ化カリウムの混合水溶液中に沈めて含浸させてもよい。 The NOx absorbent prepared in the same manner as in the production method of Comparative Example 2 is further submerged in a potassium iodide aqueous solution having a predetermined concentration, and the support is impregnated with potassium iodide. This was then dried. As a result, as shown in FIG. 3, from a composition of 25% by weight of activated carbon, 45% by weight of calcium hydroxide, 7% by weight of calcium sulfate, 18% by weight of potassium hydroxide and 5% by weight of potassium iodide impregnated therein. A NOx absorbent (Example 2) was prepared. In addition, as a manufacturing method of the NOx absorbent according to Example 2, an activated carbon carrier may be submerged in a mixed aqueous solution of potassium hydroxide and potassium iodide.
次に、実施例２及び比較例２に係るＮＯｘ吸収剤のＮＯｘ浄化性能について試験した。試験方法としては、体積５ｍｌのＮＯｘ吸収剤に、温度２０℃、相対湿度６０％、ＮＯ2濃度１０ｐｐｍの空気を、空塔速度ＳＶ（＝通ガス流量(ｍ3／ｈ)／吸収剤容量(ｍ3)）27000ｈ-1で通過させて、ＮＯｘ浄化性能を試験した。 Next, the NOx purification performance of the NOx absorbents according to Example 2 and Comparative Example 2 was tested. As a test method, a NOx absorbent having a volume of 5 ml, an air having a temperature of 20 ° C., a relative humidity of 60%, and a NO 2 concentration of 10 ppm were used, and the superficial velocity SV (= gas flow rate (m 3 / h) / absorbent capacity ( m 3 )) Passed at 27000 h −1 to test NOx purification performance.
図２は、ＮＯｘ浄化性能の試験結果を示すグラフである。同図に示すように、比較例２よりも実施例２に係るＮＯｘ吸収剤の方が、高いＮＯ2除去率が長時間にわたって維持されていることが分かる。図３にＮＯｘ除去性能をまとめて示すように、実施例２に係るＮＯｘ吸収剤は、初期（例えば、通ガス時間１時間）のＮＯ2除去率は１００％であり、ＮＯ2除去率９０％以上を維持する時間が１２２時間であった。また、ＮＯ2除去率が９０％以上を維持できなくなった時点におけるＫＯＨ利用率は２６％であった。 FIG. 2 is a graph showing the test results of the NOx purification performance. As shown in the figure, it can be seen that the NOx absorbent according to Example 2 maintains a higher NO 2 removal rate over a longer time than Comparative Example 2. As shown collectively NOx removal performance in Figure 3, NOx absorbing agent according to the second embodiment, the initial (e.g., passing the gas over 1 hour) NO 2 removal rate is 100%, NO 2 removal of 90% The time for maintaining the above was 122 hours. Further, the KOH utilization rate at the time when the NO 2 removal rate could not be maintained at 90% or more was 26%.
これに対して、比較例２に係るＮＯｘ吸収剤は、初期（例えば、通ガス時間１時間）のＮＯ2除去率は９７％であり、ＮＯ2除去率９０%以上を維持する時間が８０時間であった。また、ＮＯ2除去率が９０％以上を維持できなくなった時点におけるＫＯＨ利用率は１７％であった。 In contrast, NOx absorbent of Comparative Example 2, the initial (e.g., passing the gas over 1 hour) NO 2 removal rate is 97%, the time for maintaining the NO 2 removal of 90% or more 80 hours Met. Further, the KOH utilization rate when the NO 2 removal rate could not be maintained at 90% or more was 17%.
すなわち、実施例２に係るＮＯｘ吸収剤は、比較例２に係るＮＯｘ吸収剤に比べて、高いＮＯｘ除去率を長時間にわたって維持すると共に、ＫＯＨ利用率が高く、ＮＯｘ吸収物質を有効に活用している吸収剤であることが分かる。 That is, the NOx absorbent according to Example 2 maintains a high NOx removal rate for a long time as compared with the NOx absorbent according to Comparative Example 2, and has a high KOH utilization rate, and effectively utilizes the NOx absorbent. It turns out that it is an absorbent.
上述するように、流通ガス中のＮＯｘがＮＯｘ吸収物質に化学吸収される反応の速度は比較的遅いため、ＮＯｘ吸収物質のみでは、比較例２に係るＮＯｘ吸収剤のように、ＮＯｘ吸収性能は十分ではない。 As described above, since the rate of reaction in which NOx in the circulating gas is chemically absorbed by the NOx absorbent is relatively slow, the NOx absorbent performance of the NOx absorbent alone is not the same as the NOx absorbent according to Comparative Example 2. Not enough.
これに対して、実施例２に係るＮＯｘ吸収剤には、ＮＯｘ吸収物質である水酸化カリウムに加えて、ＮＯｘのイオン化剤であるヨウ化カリウムが担持されており、実施例１と同様に、ＮＯｘ除去効率の向上、ＮＯｘ吸収物質の利用率の向上を達成したものと考えられる。 In contrast, the NOx absorbent according to Example 2 carries potassium iodide, which is an ionizing agent for NOx, in addition to potassium hydroxide, which is a NOx absorbent, and as in Example 1, It is considered that the NOx removal efficiency and the utilization rate of the NOx absorbing material have been improved.
＜実施例１と実施例２の比較＞
実施例１に係るＮＯｘ吸収剤は、担体を主として活性炭から構成した。この結果、活性炭の有する大きな比表面積を利用して、ＮＯｘ吸収性能を向上させることができる。また、ＮＯｘ吸収剤を低コストで製造することができるため、使い捨ての吸収剤とすることができる。また、使い捨ての利用方法とすれば、担体に対して再生作業に伴う強度を付与する必要がないため、活性炭で形成した耐久性で十分となる。
<Comparison of Example 1 and Example 2>
In the NOx absorbent according to Example 1, the carrier was mainly composed of activated carbon. As a result, the NOx absorption performance can be improved by utilizing the large specific surface area of the activated carbon. Further, since the NOx absorbent can be manufactured at a low cost, it can be a disposable absorbent. Moreover, if it is set as a disposable utilization method, since it is not necessary to provide the intensity | strength accompanying a reproduction | regeneration operation | work with respect to a support | carrier, the durability formed with activated carbon will be enough.
これに対して、実施例２に係るＮＯｘ吸収剤は、担体として活性炭に加えて、さらに、カルシウムの水酸化物及び硫酸塩を含有させて構成した。この結果、担体の耐久性を向上させることができる。ＮＯｘ吸収剤は、換気ガスの浄化コストの低減などを目的として、再生して再び使用することが多いため、担体の耐久性を向上させて再生作業に耐えうるようにすることは有利となる。 On the other hand, the NOx absorbent according to Example 2 was configured to contain calcium hydroxide and sulfate in addition to activated carbon as a carrier. As a result, the durability of the carrier can be improved. Since the NOx absorbent is often regenerated and reused for the purpose of reducing the purification cost of the ventilation gas, it is advantageous to improve the durability of the carrier so that it can withstand the regenerating work.
担体の材質として、活性炭と耐久性向上剤との混合物で構成するよりも、主として活性炭から構成した方がＮＯｘとの接触確率が高いため、一般的にＮＯｘ除去率が高い。図３に示したデータでは、実施例１よりも実施例２の方がＮＯｘ除去率や９０％維持時間について性能が優れているが、これは、ＮＯｘ吸収物質であるＫＯＨの担持量の差に起因するものと考えられる。 Compared to a mixture of activated carbon and a durability improver as the material of the carrier, the NOx removal rate is generally high because the contact probability with NOx is higher when it is mainly composed of activated carbon. In the data shown in FIG. 3, the performance of Example 2 is superior to Example 1 in terms of NOx removal rate and 90% maintenance time. This is due to the difference in the amount of KOH that is a NOx absorbent. It is thought to be caused.
＜その他の構成について＞
イオン化剤としては、ＮＯｘをイオン化することができるものであればよく、ヨウ化カリウムの他に、鉄（II）の塩又はスズ（II）の塩などがあげられる。また、担体の材質として活性炭に耐久性向上剤と混合させる場合には、耐久性向上剤としては、カルシウム又はアルミニウムの水酸化物、酸化物、炭酸塩又は硫酸塩などがあげられる。
<Other configuration>
Any ionizing agent may be used as long as it can ionize NOx. Examples of the ionizing agent include iron (II) salt and tin (II) salt in addition to potassium iodide. When the carrier material is mixed with activated carbon and a durability improver, examples of the durability improver include calcium or aluminum hydroxides, oxides, carbonates or sulfates.
ＮＯｘ吸収物質は、ＮＯｘ吸収剤全体に対して３〜４０重量％、好ましくは１０〜３０重量％担持させる。また、イオン化剤は、ＮＯｘ吸収剤全体に対して１〜２０重量％、好ましくは１〜１２重量％担持させる。下限値よりも少量であるとＮＯｘのイオン化による吸収反応速度の向上の効果が得られず、上限値よりも多量であると無駄な担持量が発生する。 The NOx absorbing material is supported by 3 to 40% by weight, preferably 10 to 30% by weight, based on the entire NOx absorbent. Further, the ionizing agent is supported in an amount of 1 to 20% by weight, preferably 1 to 12% by weight, based on the entire NOx absorbent. If the amount is smaller than the lower limit value, the effect of improving the absorption reaction rate due to the ionization of NOx cannot be obtained, and if it is larger than the upper limit value, a wasteful loading amount is generated.
担体を主として活性炭で構成する場合には、ＮＯｘ吸収剤全体に対して２０〜９５重量％、好ましくは６０〜９０重量％で構成する。下限値よりも少量であると比表面積低下に伴いＮＯｘ浄化効率が減少し、上限値よりも多量であると担体としての耐久性が著しく低下する。また、担体に耐久性向上剤を含有させる場合には、ＮＯｘ吸収剤全体に対して３０〜８０重量％、好ましくは４０〜６０重量％で構成する。下限値よりも少量であると耐久性向上剤の作用が弱くなり、上限値よりも多量であると比表面積低下に伴いＮＯｘ浄化効率が減少する。 When the carrier is mainly composed of activated carbon, it is composed of 20 to 95% by weight, preferably 60 to 90% by weight, based on the entire NOx absorbent. If the amount is less than the lower limit value, the NOx purification efficiency decreases as the specific surface area decreases, and if it is more than the upper limit value, the durability as a carrier is significantly reduced. Moreover, when making a support | carrier contain a durability improver, it comprises 30 to 80 weight% with respect to the whole NOx absorbent, Preferably it comprises 40 to 60 weight%. When the amount is less than the lower limit value, the effect of the durability improving agent is weakened, and when the amount is more than the upper limit value, the NOx purification efficiency decreases as the specific surface area decreases.
また、担体の形状は、ハニカム形状の他に、コルゲート形状、粉体、ペレット形状、繊維状又はシート形状などが考えられる。ＮＯｘ吸収剤を適用する場所に応じて適宜選択することができる。 In addition to the honeycomb shape, the shape of the carrier may be a corrugated shape, a powder, a pellet shape, a fiber shape or a sheet shape. It can select suitably according to the place which applies a NOx absorbent.
Claims (8)
前記担体に、更に、窒素酸化物をイオン化するイオン化剤を担持させたことを特徴とする窒素酸化物吸収剤。 In the nitrogen oxide absorbent formed by supporting at least one nitrogen oxide absorbing material of alkali metal hydroxide, oxide or carbonate on the carrier,
A nitrogen oxide absorbent characterized in that an ionizing agent that ionizes nitrogen oxide is further supported on the carrier.
前記イオン化剤は、ヨウ化カリウム、鉄（II）の塩又はスズ（II）の塩のうち少なくとも１つであることを特徴とする窒素酸化物吸収剤。 In the nitrogen oxide absorbent according to claim 1,
The nitrogen oxide absorbent according to claim 1, wherein the ionizing agent is at least one of potassium iodide, iron (II) salt or tin (II) salt.
前記担体は、活性炭であることを特徴とする窒素酸化物吸収剤。 In the nitrogen oxide absorbent according to claim 1,
The nitrogen oxide absorbent, wherein the carrier is activated carbon.
前記担体は、カルシウム又はアルミニウムの水酸化物、酸化物、炭酸塩又は硫酸塩のうち少なくとも１つを含有することを特徴とする窒素酸化物吸収剤。 In the nitrogen oxide absorbent according to claim 1,
The nitrogen oxide absorbent according to claim 1, wherein the carrier contains at least one of calcium, aluminum hydroxide, oxide, carbonate or sulfate.
前記イオン化剤は、窒素酸化物吸収剤全体に対して１〜２０重量％であることを特徴とする窒素酸化物吸収剤。 In the nitrogen oxide absorbent according to claim 2,
The nitrogen oxide absorbent, wherein the ionizing agent is 1 to 20% by weight with respect to the whole nitrogen oxide absorbent.
前記窒素酸化物吸収物質は窒素酸化物吸収剤全体に対して３〜４０重量％であり、前記活性炭は窒素酸化物吸収剤全体に対して２０〜９５重量％であることを特徴とする窒素酸化物吸収剤。 In the nitrogen oxide absorbent according to claim 3,
The nitrogen oxide absorbing material is 3 to 40% by weight with respect to the whole nitrogen oxide absorbent, and the activated carbon is 20 to 95% by weight with respect to the whole nitrogen oxide absorbent. Absorber.
前記窒素酸化物吸収物質は窒素酸化物吸収剤全体に対して３〜４０重量％であり、前記カルシウム又はアルミニウムの水酸化物、酸化物、炭酸塩又は硫酸塩のうち少なくとも１つは窒素酸化物吸収剤全体に対して３０〜８０重量％であることを特徴とする窒素酸化物吸収剤。 In the nitrogen oxide absorbent according to claim 4,
The nitrogen oxide absorbing material is 3 to 40% by weight based on the whole nitrogen oxide absorbent, and at least one of the calcium or aluminum hydroxide, oxide, carbonate or sulfate is nitrogen oxide. A nitrogen oxide absorbent characterized by being 30 to 80% by weight based on the whole absorbent.
前記担体の形状は、ハニカム形状、コルゲート形状、粉体、ペレット形状、繊維状又はシート形状のいずれかであることを特徴とする窒素酸化物吸収剤。 In the nitrogen oxide absorbent according to claim 1,
The nitrogen oxide absorbent according to claim 1, wherein the carrier has any one of a honeycomb shape, a corrugated shape, a powder shape, a pellet shape, a fiber shape, and a sheet shape.
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| JPH01176450A (en) * | 1987-12-29 | 1989-07-12 | Matsushita Electric Ind Co Ltd | Absorbent for nitrogen oxide and sulfur oxide |
| JPH02139035A (en) * | 1988-08-17 | 1990-05-29 | Hitachi Plant Eng & Constr Co Ltd | Air purification agent |
| JPH0490849A (en) * | 1990-08-03 | 1992-03-24 | Sakai Chem Ind Co Ltd | Nitrogen oxide adsorbing agent |
| JPH0739749A (en) * | 1993-04-29 | 1995-02-10 | Esupo Kk | Air cleaning agent to be put in space and air cleaning method |
| JP2003245552A (en) * | 2002-02-22 | 2003-09-02 | Mazda Motor Corp | Catalyst for cleaning exhaust gas and exhaust gas cleaning apparatus for diesel engine |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01176450A (en) * | 1987-12-29 | 1989-07-12 | Matsushita Electric Ind Co Ltd | Absorbent for nitrogen oxide and sulfur oxide |
| JPH02139035A (en) * | 1988-08-17 | 1990-05-29 | Hitachi Plant Eng & Constr Co Ltd | Air purification agent |
| JPH0490849A (en) * | 1990-08-03 | 1992-03-24 | Sakai Chem Ind Co Ltd | Nitrogen oxide adsorbing agent |
| JPH0739749A (en) * | 1993-04-29 | 1995-02-10 | Esupo Kk | Air cleaning agent to be put in space and air cleaning method |
| JP2003245552A (en) * | 2002-02-22 | 2003-09-02 | Mazda Motor Corp | Catalyst for cleaning exhaust gas and exhaust gas cleaning apparatus for diesel engine |
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