JP4773765B2 - Urea aqueous solution - Google Patents
Urea aqueous solution Download PDFInfo
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- JP4773765B2 JP4773765B2 JP2005226727A JP2005226727A JP4773765B2 JP 4773765 B2 JP4773765 B2 JP 4773765B2 JP 2005226727 A JP2005226727 A JP 2005226727A JP 2005226727 A JP2005226727 A JP 2005226727A JP 4773765 B2 JP4773765 B2 JP 4773765B2
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- urea
- aqueous solution
- nox
- precipitation
- solution
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- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims description 50
- 239000004202 carbamide Substances 0.000 title claims description 50
- 239000007864 aqueous solution Substances 0.000 title claims description 18
- 238000001556 precipitation Methods 0.000 claims description 20
- XLJMAIOERFSOGZ-UHFFFAOYSA-N cyanic acid Chemical compound OC#N XLJMAIOERFSOGZ-UHFFFAOYSA-N 0.000 claims description 18
- 239000003112 inhibitor Substances 0.000 claims description 8
- XLJMAIOERFSOGZ-UHFFFAOYSA-M cyanate Chemical compound [O-]C#N XLJMAIOERFSOGZ-UHFFFAOYSA-M 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 229910002089 NOx Inorganic materials 0.000 description 22
- 239000003054 catalyst Substances 0.000 description 14
- 239000000243 solution Substances 0.000 description 12
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 10
- 239000007789 gas Substances 0.000 description 6
- 229910021529 ammonia Inorganic materials 0.000 description 5
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 5
- WTHDKMILWLGDKL-UHFFFAOYSA-N urea;hydrate Chemical compound O.NC(N)=O WTHDKMILWLGDKL-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000007596 consolidation process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 239000007798 antifreeze agent Substances 0.000 description 1
- 239000013556 antirust agent Substances 0.000 description 1
- QYTOONVFPBUIJG-UHFFFAOYSA-N azane;cyanic acid Chemical compound [NH4+].[O-]C#N QYTOONVFPBUIJG-UHFFFAOYSA-N 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000003203 everyday effect Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- GKKCIDNWFBPDBW-UHFFFAOYSA-M potassium cyanate Chemical compound [K]OC#N GKKCIDNWFBPDBW-UHFFFAOYSA-M 0.000 description 1
- ZVCDLGYNFYZZOK-UHFFFAOYSA-M sodium cyanate Chemical compound [Na]OC#N ZVCDLGYNFYZZOK-UHFFFAOYSA-M 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
本発明は、尿素水における尿素の析出を効果的に抑制することができる尿素水溶液に関する。特にはＮＯｘ触媒に好適に使用することができる尿素水溶液に関する。 The present invention relates to an aqueous urea solution that can effectively suppress precipitation of urea in urea water. In particular, the present invention relates to an aqueous urea solution that can be suitably used for a NOx catalyst.
大気汚染や地球温暖化などの環境問題への対策の一環として、トラックなどのディーゼル車から排出される窒素酸化物を削減するＮＯｘ触媒の開発が進められている。 As part of measures to address environmental problems such as air pollution and global warming, NOx catalysts that reduce nitrogen oxides emitted from diesel vehicles such as trucks are being developed.
現在までに開発されたＮＯｘ触媒としては、酸化触媒やガソリン自動車で実用化されている三元触媒などがあるが、いずれも十分なＮＯｘの浄化が困難であった。近年、ＮＯｘ浄化に有望な触媒である還元型ＮＯｘ触媒が提案され、そのさらなる開発が行われている。 Examples of NOx catalysts that have been developed to date include oxidation catalysts and three-way catalysts that have been put to practical use in gasoline automobiles. However, it has been difficult to sufficiently purify NOx. In recent years, reduction-type NOx catalysts, which are promising catalysts for NOx purification, have been proposed and further developed.
この還元型ＮＯｘ触媒は、アンモニアなどの還元剤の存在下でＮＯｘを浄化する触媒である。例えば、尿素水タンクからＮＯｘ触媒の上流側の排気系に尿素水溶液を添加し、排気ガスの熱によって尿素水溶液中の尿素を加水分解してアンモニアとし、このアンモニアを還元剤として排気ガス中のＮＯｘと反応させて、排気ガス中のＮＯｘを浄化するという反応システムを利用したものである。 This reduced NOx catalyst is a catalyst that purifies NOx in the presence of a reducing agent such as ammonia. For example, an aqueous urea solution is added from the urea water tank to the exhaust system upstream of the NOx catalyst, the urea in the aqueous urea solution is hydrolyzed to ammonia by the heat of the exhaust gas, and this ammonia is used as a reducing agent to reduce NOx in the exhaust gas. And a reaction system that purifies NOx in the exhaust gas.
還元剤としてアンモニアが排気ガス中のＮＯｘ、例えば一酸化窒素ＮＯや二酸化窒素ＮＯ2と反応して、排気ガス中のＮＯｘが無害なＮやＨ2Ｏに変換して浄化される過程を化学式で示すと以下のとおりとなる。 As a reducing agent, a process in which ammonia reacts with NOx in exhaust gas, for example, nitrogen monoxide NO or nitrogen dioxide NO 2, and NOx in the exhaust gas is converted into harmless N or H 2 O to be purified by a chemical formula. The result is as follows.
４ＮＯ＋４ＮＨ3＋Ｏ2 → ４Ｎ2＋６Ｈ2Ｏ
ＮＯ＋４ＮＯ2＋２ＮＨ3 → ２Ｎ2＋３Ｈ2Ｏ
ところが、このＮＯｘ触媒の場合、ＮＯｘがアンモニアと反応することによりＮＯｘの浄化が行われるため、例えば尿素水溶液がタンクから排気系に添加されるまでに通過する供給管において析出物が生じ、目詰まりを起こしてしまう場合など、尿素水が安定して供給されないと、ＮＯｘ触媒が十分な浄化作用を発揮しなくなってしまうという課題があった。
4NO + 4NH 3 + O 2 → 4N 2 + 6H 2 O
NO + 4NO 2 + 2NH 3 → 2N 2 + 3H 2 O
However, in the case of this NOx catalyst, NOx is purified by the reaction of NOx with ammonia. For example, precipitates are generated and clogged in the supply pipe through which the aqueous urea solution passes from the tank to the exhaust system. When the urea water is not supplied stably, there is a problem that the NOx catalyst does not exhibit a sufficient purification action.
そこで、尿素水溶液がＮＯｘ触媒に安定供給されるように、目詰まりの原因となる尿素水中の尿素の析出を抑える試みがなされている。例えば尿素水溶液中にホルムアルデヒド、メタノール、アセトン及びアセトアルデヒドなどの析出抑制剤を添加して、液中の尿素の析出（固結）を抑制することが行われていた（例えば特許文献１参照）。
しかし、従来の方法では、尿素水溶液がタンクから排気系に添加されるまでに通過する供給管や供給管端部等に生じる析出物を充分に抑制することができなかった。 However, in the conventional method, precipitates generated in the supply pipe, the supply pipe end, and the like that pass before the urea aqueous solution is added from the tank to the exhaust system cannot be sufficiently suppressed.
本発明は、このような事情に鑑みなされたものであり、尿素水溶液における尿素の析出をより効果的に抑制することができる尿素水溶液を提供することを目的とするものである。 This invention is made | formed in view of such a situation, and it aims at providing the urea aqueous solution which can suppress precipitation of urea in a urea aqueous solution more effectively.
上記目的を達成するため、本発明は、水及び尿素を主成分とし、前記主成分中にシアン酸又はシアン酸塩からなる析出抑制剤を含有することを特徴とする尿素水溶液をその要旨とした。 In order to achieve the above object, the gist of the present invention is an aqueous urea solution characterized in that it contains water and urea as main components, and the main component contains a precipitation inhibitor composed of cyanic acid or cyanate. .
本発明の尿素水溶液は、液中のシアン酸又はシアン酸塩からなる析出抑制剤が尿素の析出（固結）を効果的に抑制するので、当該尿素水溶液がタンクから排気系に添加されるまでに通過する供給管において尿素が析出して目詰まりが生じる恐れが少なく、尿素水のＮＯｘ触媒への安定供給を実現し得て、ＮＯｘの確実な浄化作用が期待できる。 In the urea aqueous solution of the present invention, since the precipitation inhibitor composed of cyanic acid or cyanate in the liquid effectively suppresses urea precipitation (consolidation), until the urea aqueous solution is added from the tank to the exhaust system. There is little possibility that urea will precipitate and clog in the supply pipe that passes through, so that stable supply of urea water to the NOx catalyst can be realized, and a reliable purification action of NOx can be expected.
以下、本発明の尿素水溶液を説明する。本発明の尿素水溶液における主成分は、水及び尿素である。当該尿素水溶液における尿素の含有量としては特に限定されないが、１０〜５０重量％、好ましくは２０〜４０重量％、より好ましくは２５〜３５重量％である。尿素の含有量が１０重量％を下回ると、当該尿素水溶液を用いて排気ガス中のＮＯｘの浄化を行う際に、脱硝効率が低くなり、尿素の含有量が５０重量％を上回る場合には、含有量上昇に伴う脱硝効果が期待できず、不経済となる。 Hereinafter, the urea aqueous solution of the present invention will be described. The main components in the urea aqueous solution of the present invention are water and urea. Although it does not specifically limit as content of urea in the said urea aqueous solution, It is 10 to 50 weight%, Preferably it is 20 to 40 weight%, More preferably, it is 25 to 35 weight%. When the urea content is less than 10% by weight, the NOx removal efficiency is reduced when purifying NOx in the exhaust gas using the urea aqueous solution, and when the urea content exceeds 50% by weight, The denitration effect accompanying the increase in the content cannot be expected, which is uneconomical.
前記主成分中にシアン酸又はシアン酸塩からなる析出抑制剤が含まれている。シアン酸塩としては、例えばシアン酸ナトリウム、シアン酸カリウム、シアン酸アンモニウムなどを挙げることができる。 The main component contains a precipitation inhibitor composed of cyanic acid or cyanate. Examples of the cyanate include sodium cyanate, potassium cyanate, and ammonium cyanate.
上記シアン酸又はシアン酸塩からなる析出抑制剤は、液中に０．００１重量％以上、１重量％未満の含有量で含まれていることが望ましい。析出抑制剤の含有量が０．００１重量％を下回る場合、十分な尿素の析出抑制効果が得られず、１重量％以上の場合には、多く使用しただけの効果が期待できず、不経済となる。 The precipitation inhibitor composed of cyanic acid or cyanate is preferably contained in the liquid at a content of 0.001 wt% or more and less than 1 wt%. When the content of the precipitation inhibitor is less than 0.001% by weight, a sufficient urea precipitation inhibitory effect cannot be obtained, and when it is 1% by weight or more, the effect of using only a large amount cannot be expected, which is uneconomical. It becomes.
尚、本発明の尿素水溶液には、必要に応じて従来公知の防錆剤、凍結防止剤などの添加剤を適宜添加することもできる。 In addition, additives, such as a conventionally well-known antirust agent and antifreeze agent, can also be suitably added to the urea aqueous solution of this invention as needed.
以下、本発明の尿素水溶液を実施例に従ってさらに詳しく説明する。 Hereinafter, the urea aqueous solution of the present invention will be described in more detail with reference to examples.
実施例１
水に３２．５重量％の尿素を添加して尿素水溶液を調製し、これにシアン酸を１０ｐｐｍを加えてサンプルとした。
Example 1
A urea aqueous solution was prepared by adding 32.5% by weight of urea to water, and 10 ppm of cyanic acid was added thereto to prepare a sample.
実施例２
実施例１の３２．５％濃度の尿素水溶液にシアン酸を１００ｐｐｍを加えてサンプルとした。
Example 2
A sample was prepared by adding 100 ppm of cyanic acid to the 32.5% concentration aqueous urea solution of Example 1.
実施例３
実施例１の３２．５％濃度の尿素水溶液にシアン酸を１０００ｐｐｍを加えてサンプルとした。
Example 3
A sample was prepared by adding 1000 ppm of cyanic acid to the 32.5% concentration aqueous urea solution of Example 1.
比較例
実施例１の３２．５％濃度の尿素水溶液のみからなるものを比較のためのサンプルとした。
Comparative Example A sample for comparison was made of only the 32.5% aqueous urea solution of Example 1.
上記実施例１〜３並びに比較例の各サンプルについて、尿素の析出実験を行った。尿素の析出実験は、実施例１〜３並びに比較例の各サンプルをそれぞれ１００ｍｌのビーカーに１０ｍｌずつ入れ、これらを２３±５℃で放置し、一日毎の析出の有無を確認するという方法で行った。その結果を表１に示した。 A urea precipitation experiment was performed on each of the samples of Examples 1 to 3 and the comparative example. The urea precipitation experiment was performed by a method in which 10 ml of each sample of Examples 1 to 3 and the comparative example was placed in a 100 ml beaker and left at 23 ± 5 ° C. to check for precipitation every day. It was. The results are shown in Table 1.
Claims (3)
The urea aqueous solution according to claim 1 or 2, wherein the content of the precipitation inhibitor comprising cyanic acid or cyanate is 0.001 wt% or more and less than 1 wt%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005226727A JP4773765B2 (en) | 2005-08-04 | 2005-08-04 | Urea aqueous solution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005226727A JP4773765B2 (en) | 2005-08-04 | 2005-08-04 | Urea aqueous solution |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2007039393A JP2007039393A (en) | 2007-02-15 |
| JP4773765B2 true JP4773765B2 (en) | 2011-09-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP2005226727A Expired - Fee Related JP4773765B2 (en) | 2005-08-04 | 2005-08-04 | Urea aqueous solution |
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| Country | Link |
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Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08259442A (en) * | 1995-03-17 | 1996-10-08 | Shiseido Co Ltd | Composition containing urea at high concentration and prevention of crystal deposition of urea |
| JP2001131063A (en) * | 1999-10-29 | 2001-05-15 | Eisai Co Ltd | Method for inhibiting crystallization of urea in urea- formulated composition |
| JP4401669B2 (en) * | 2003-03-27 | 2010-01-20 | 三菱ふそうトラック・バス株式会社 | Urea water for reducing denitration and denitration apparatus using the same |
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