JP2732611B2 - Method for preparing rhodium-containing solution for producing exhaust purification catalyst - Google Patents
Method for preparing rhodium-containing solution for producing exhaust purification catalystInfo
- Publication number
- JP2732611B2 JP2732611B2 JP63255792A JP25579288A JP2732611B2 JP 2732611 B2 JP2732611 B2 JP 2732611B2 JP 63255792 A JP63255792 A JP 63255792A JP 25579288 A JP25579288 A JP 25579288A JP 2732611 B2 JP2732611 B2 JP 2732611B2
- Authority
- JP
- Japan
- Prior art keywords
- rhodium
- solution
- catalyst
- nitric acid
- containing solution
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Catalysts (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は、内燃機関等から排出される排気を浄化す
る触媒を製造するためのロジウム含有溶液の調製方法に
関する。Description: TECHNICAL FIELD The present invention relates to a method for preparing a rhodium-containing solution for producing a catalyst for purifying exhaust gas discharged from an internal combustion engine or the like.
担体にロジウムを担持させて触媒を製造する方法の一
つとして、ロジウム塩の溶液に担体を浸漬させる方法が
ある。この際使用されるロジウム塩としては、従来、塩
化ロジウムまたは硝酸ロジウムが用いられている。As one of methods for producing a catalyst by supporting rhodium on a carrier, there is a method of immersing the carrier in a rhodium salt solution. As the rhodium salt used at this time, rhodium chloride or rhodium nitrate has been conventionally used.
しかしながら塩化ロジウム、特にその４水塩は、分解
温度が約800℃と高く、これを担持させた触媒は初期性
能に劣るという問題点がある。ここで分解温度とは、ロ
ジウムと共に担体に吸着された塩素が加熱により揮散
し、担体から除去される温度をいう。However, rhodium chloride, particularly its tetrahydrate, has a problem that the decomposition temperature is as high as about 800 ° C., and the catalyst supporting the same has poor initial performance. Here, the decomposition temperature refers to a temperature at which chlorine adsorbed on the carrier together with rhodium volatilizes by heating and is removed from the carrier.
これに対して、硝酸ロジウムは、ロジウムと共に担体
に吸着された硝酸が揮散する分解温度が塩化ロジウムよ
りも低いために、初期性能に関してはなんら問題はな
い。On the other hand, rhodium nitrate has no problem in initial performance because the decomposition temperature at which nitric acid adsorbed on the carrier together with rhodium evaporates is lower than that of rhodium chloride.
〔発明が解決しようとする課題〕 ところが、硝酸ロジウムは担体に担持させる際の担持
歩留りが塩化ロジウムよりも低く、塩化ロジウムを用い
た場合と同量のロジウムを担持させようとすると、大量
のロジウムが必要となる。このため、未担持のロジウム
も大量に残存することになる。ロジウムは希少資源であ
って高価なので、このような未担持のロジウムは回収す
ることが望ましいが、そのような工程を入れることは、
工程の繁雑化を招きコストの増大につながる。[Problems to be Solved by the Invention] However, rhodium nitrate has a lower loading yield when supported on a carrier than rhodium chloride. Is required. Therefore, a large amount of unsupported rhodium also remains. Rhodium is a scarce resource and expensive, so it is desirable to recover such unsupported rhodium, but including such a step
The process becomes complicated, which leads to an increase in cost.
したがって、この発明は、製造された触媒の初期性能
を劣化させることなく、高い歩留りで担体にロジウムを
担持させることができる排気浄化触媒製造用のロジウム
含有溶液、の調製方法を提供することを目的とする。Accordingly, an object of the present invention is to provide a method for preparing a rhodium-containing solution for producing an exhaust purification catalyst, which can support rhodium on a carrier at a high yield without deteriorating the initial performance of the produced catalyst. And
この発明の排気浄化触媒製造用ロジウム含有溶液は、
次のような方法によって調製することができる。ａ）水
酸化ロジウムの結晶と、ロジウム１モルに対して0.1モ
ル以上の含有量の、１以上のカルボキシル基を有する水
溶性有機酸とを混合して硝酸に溶解し、得られた溶液か
ら結晶化によって硝酸ロジウムの結晶を得、この結晶を
希硝酸に再溶解する方法。The rhodium-containing solution for producing an exhaust purification catalyst of the present invention comprises:
It can be prepared by the following method. a) A crystal of rhodium hydroxide and a water-soluble organic acid having at least one carboxyl group in a content of at least 0.1 mol per 1 mol of rhodium are mixed and dissolved in nitric acid, and crystals are obtained from the resulting solution. A method of obtaining crystals of rhodium nitrate by chemical conversion and redissolving the crystals in dilute nitric acid.
上記１以上のカルボキシル基を有する水溶性有機酸と
しては、例えば、グリコール酸、乳酸等のモノカルボン
酸、酒石酸、シュウ酸等のジカルボン酸、クエン酸等の
トリカルボン酸を使用することができる。上記有機酸の
含有量は、ロジウム１モルに対して0.1モル以上であ
り、好ましくは１〜30モルである。As the water-soluble organic acid having one or more carboxyl groups, for example, monocarboxylic acids such as glycolic acid and lactic acid, dicarboxylic acids such as tartaric acid and oxalic acid, and tricarboxylic acids such as citric acid can be used. The content of the organic acid is 0.1 mol or more, preferably 1 to 30 mol, per 1 mol of rhodium.
結晶を得るための結晶化は、例えば、ロータリーエバ
ポレーターを用いて、500〜750mmHgの減圧下において、
60〜80℃の温浴中で行なうことができる。Crystallization to obtain crystals, for example, using a rotary evaporator, under reduced pressure of 500 to 750 mmHg,
It can be performed in a warm bath at 60 to 80 ° C.
また、結晶を再溶解するために用いる希硝酸の濃度
は、0.1〜1Nが好ましい。The concentration of dilute nitric acid used for re-dissolving the crystals is preferably 0.1 to 1N.
以下に示す各種溶液を調製した。 Various solutions shown below were prepared.
〈実施例１〉 クエン酸−硝酸混合液に水酸化ロジウムの結晶を、ロ
ジウム１モルに対してクエン酸１モルの割合で添加して
溶解し、この溶液を結晶化した。次いで、得られた結晶
を希硝酸に再溶解して溶液Ａとした。<Example 1> Crystals of rhodium hydroxide were added to a mixed solution of citric acid and nitric acid at a ratio of 1 mol of citric acid to 1 mol of rhodium and dissolved, and the solution was crystallized. Next, the obtained crystals were redissolved in diluted nitric acid to obtain a solution A.
〈実施例２〉 クエン酸−硝酸混合液に水酸化ロジウムの結晶を、ロ
ジウム１モルに対してクエン酸0.1モルとなるような割
合で溶解し、この溶液を結晶化した。次いで、得られた
結晶を希硝酸に溶解して溶液Ｂとした。Example 2 Rhodium hydroxide crystals were dissolved in a citric acid-nitric acid mixture at a ratio of 0.1 mol of citric acid to 1 mol of rhodium, and the solution was crystallized. Next, the obtained crystals were dissolved in diluted nitric acid to obtain a solution B.
〈実施例３〉 クエン酸−硝酸混合液に水酸化ロジウムの結晶を、ロ
ジウム１モルに対してクエン酸５モルとなるような割合
で溶解し、この溶液を結晶化した。次いで、得られた結
晶を希硝酸に溶解して溶液Ｃとした。Example 3 Rhodium hydroxide crystals were dissolved in a citric acid-nitric acid mixed solution at a ratio of 1 mol of rhodium to 5 mol of citric acid, and the solution was crystallized. Next, the obtained crystals were dissolved in diluted nitric acid to obtain a solution C.
〈比較例１〉 水酸化ロジウムを硝酸に溶解し、この溶液を脱気した
後、希硝酸と混合して溶液Ｄとした。<Comparative Example 1> Rhodium hydroxide was dissolved in nitric acid, and the solution was degassed.
〈比較例２〉 水酸化ロジウムを硝酸に溶解し、この溶液を脱気した
後、希硝酸と混合して溶液Ｅとした。<Comparative Example 2> Rhodium hydroxide was dissolved in nitric acid, and the solution was degassed.
〈比較例３〉 クエン酸−硝酸混合液に水酸化ロジウムの結晶を、ロ
ジウム１モルに対してクエン酸0.05モルとなるような割
合で溶解し、この溶液を結晶化した後、得られた結晶を
希硝酸に氷解して溶液Ｆとした。Comparative Example 3 Rhodium hydroxide crystals were dissolved in a citric acid-nitric acid mixed solution at a ratio of 0.05 mol of citric acid to 1 mol of rhodium, and the solution was crystallized. Was dissolved in diluted nitric acid to obtain a solution F.
〈比較例４〉 市販の塩化ロジウムの結晶を0.5Nの塩酸に溶解して溶
液Ｇとした。Comparative Example 4 A commercially available rhodium chloride crystal was dissolved in 0.5N hydrochloric acid to obtain a solution G.
〈比較例５〉 市販の硝酸ロジウム二水塩の結晶を1N硝酸に溶解して
溶液Ｈとした。Comparative Example 5 Commercially available crystals of rhodium nitrate dihydrate were dissolved in 1N nitric acid to obtain a solution H.
〈試験例１〉 硝酸ロジウム溶液および実施例３において調製した溶
液Ｃのそれぞれに対して水酸化ナトリウム溶液を用いて
滴定を行ない、水酸化ナトリウムの滴定量と溶液のpH値
との相関を求めた。結果を第１図に示す。第１図におい
て、横軸は水酸化ナトリウムの滴定量、縦軸は溶液のpH
値をそれぞれ示し、曲線ａは溶液Ｃ、曲線ｂは硝酸ロジ
ウム溶液の滴定曲線をそれぞれ表わす。<Test Example 1> Titration was performed on each of the rhodium nitrate solution and the solution C prepared in Example 3 using a sodium hydroxide solution, and the correlation between the titer of sodium hydroxide and the pH value of the solution was determined. . The results are shown in FIG. In FIG. 1, the horizontal axis is the titer of sodium hydroxide, and the vertical axis is the pH of the solution.
The curve a represents the titration curve of the solution C and the curve b represents the titration curve of the rhodium nitrate solution.
第１図から明らかなように、硝酸ロジウム溶液が少量
の水酸化ナトリウムの添加にによってpH値が急激に上昇
するのに対し、この発明の触媒製造用ロジウム含有溶液
は水酸化ナトリウムの添加に従って徐々にpH値が上昇し
ている。As is clear from FIG. 1, the rhodium nitrate solution rapidly increased its pH value with the addition of a small amount of sodium hydroxide, whereas the rhodium-containing solution for producing a catalyst of the present invention gradually increased with the addition of sodium hydroxide. PH value is increasing.
〈試験例２〉 上記実施例１〜３および比較例１〜５において調製し
た各溶液について、ロジウムの担持効率および各溶液か
ら製造される触媒の性能を評価した。<Test Example 2> For each of the solutions prepared in Examples 1 to 3 and Comparative Examples 1 to 5, the rhodium loading efficiency and the performance of the catalyst produced from each solution were evaluated.
ロジウムの担持効率の測定 表面に活性アルミナをコートし、さらにパラジウムを
１個当り0.014g担持させたモノリス担体（テストピー
ス）を、溶液ＡないしＨのそれぞれに、20℃で１時間浸
漬してロジウムを担持させ、その際の担持効率を測定し
た。結果を第１表に示す。Measurement of Rhodium Loading Efficiency A monolithic carrier (a test piece) coated with activated alumina on its surface and further supporting 0.014 g of palladium per one was immersed in each of solutions A to H at 20 ° C. for 1 hour, and then immersed in rhodium. Was carried, and the carrying efficiency at that time was measured. The results are shown in Table 1.
また、溶液Ａを用いて、ロジウムに対するクエン酸の
割合を変えて上記と同様の操作を行ない、ロジウムの担
持に及ぼすクエン酸の影響を調べた。結果を第２図に示
す。第２図において、横軸はロジウムに対するクエン酸
の割合であり、縦軸はロジウムの担持効率である。Using solution A, the same operation as described above was performed by changing the ratio of citric acid to rhodium, and the effect of citric acid on rhodium loading was examined. The results are shown in FIG. In FIG. 2, the horizontal axis is the ratio of citric acid to rhodium, and the vertical axis is the rhodium loading efficiency.
第２図から明らかなように、ロジウムに対するクエン
酸の割合が増加するに従ってロジウムの担持効率も増加
するが、ロジウムに対するクエン酸の割合が１をこえる
と担持効率はほぼ100％となり、その後はほとんど変化
がない。As is clear from FIG. 2, the loading efficiency of rhodium increases as the ratio of citric acid to rhodium increases. However, when the ratio of citric acid to rhodium exceeds 1, the loading efficiency becomes almost 100%, and after that, it becomes almost 100%. no change.
触媒の性能評価 上記方法によってロジウムを担持させたテストピース
にガスを通し、ガス中に含まれるHC、COおよびNOについ
て、それぞれ50％が浄化される温度を測定した。結果を
第１表に併記する。なお、HCとはプロパンとプロピレン
の混合気体を表わすものであり、その比率はHC1000ppm
中プロパン800ppmおよびプロピレン200ppmである。Evaluation of catalyst performance A gas was passed through a test piece carrying rhodium by the above method, and the temperature at which 50% of each of HC, CO and NO contained in the gas was purified was measured. The results are shown in Table 1. Note that HC refers to a mixed gas of propane and propylene, and the ratio is HC 1000 ppm.
Medium propane 800 ppm and propylene 200 ppm.
この評価において、触媒として用いたモノリス担体
（400セル／平方インチ）の容量はφ30mm×20mmであ
り、触媒に通したガスの流量は23.0l/分である。ガスは
以下に示す組成を有するモデルガスを用いた。In this evaluation, the capacity of the monolithic carrier (400 cells / square inch) used as the catalyst was φ30 mm × 20 mm, and the flow rate of the gas passed through the catalyst was 23.0 l / min. The gas used was a model gas having the following composition.
モデルガスの組成 HC 1000ppm NO 800ppm CO 0.5％ CO2 10％ Ｈ2Ｏ 10％ H2 0.2％ Ｏ2 化学量論的量 N2 残部 第１表から明らかなように、この発明によって調製さ
れた触媒製造用ロジウム含有溶液の担持効率は塩化ロジ
ウム溶液と同程度もしくはそれ以上であり、非常に優れ
ている。Model gas composition HC 1000 ppm NO 800 ppm CO 0.5% CO 2 10% H 2 O 10% H 2 0.2% O 2 stoichiometric amount N 2 balance As is clear from Table 1, the loading efficiency of the rhodium-containing solution for preparing a catalyst prepared according to the present invention is comparable to or higher than that of the rhodium chloride solution, and is very excellent.
また、この発明によって調製された触媒製造用ロジウ
ム含有溶液によって製造された触媒は、HC、CO、NOのい
ずれにおいても、50％浄化に要する温度が比較例の溶液
から製造した触媒よりも低いことが表から明らかであ
り、この発明によって調製された触媒製造用ロジウム含
有溶液によって性能の高い触媒を製造することができる
ことがわかる。Further, in the catalyst produced by the rhodium-containing solution for producing a catalyst prepared according to the present invention, the temperature required for 50% purification in any of HC, CO, and NO is lower than that of the catalyst produced from the solution of the comparative example. Is clear from the table, and it is understood that a high-performance catalyst can be produced by the rhodium-containing solution for producing a catalyst prepared according to the present invention.
以上のように、この発明によって調製された排気浄化
触媒製造用ロジウム含有溶液から製造される触媒は、初
期性能を劣化させることなく、高い歩留りで担体にロジ
ウムを担持させることができる。As described above, the catalyst produced from the rhodium-containing solution for producing an exhaust purification catalyst prepared according to the present invention can support rhodium on a carrier at a high yield without deteriorating initial performance.
第１図は硝酸ロジウム溶液およびこの発明によって調製
された触媒製造用ロジウム含有溶液の水酸化ナトリウム
を用いた滴定曲線を示すグラフ図、第２図は実施例１に
おいて調製した溶液Ａにおけるロジウムに対するクエン
酸の割合の変化に対する担持効率の変化を示すグラフ図
である。FIG. 1 is a graph showing titration curves of a rhodium nitrate solution and a rhodium-containing solution for catalyst production prepared according to the present invention using sodium hydroxide. FIG. 2 is a graph showing the quenching of rhodium in solution A prepared in Example 1. It is a graph which shows the change of the loading efficiency with respect to the change of the ratio of an acid.
Claims (1)
１モルに対して0.1モル以上の含有量の、１以上のカル
ボキシル基を有する水溶性有機酸とを混合して硝酸に溶
解して溶液を得る工程と、 ｂ） 該溶液から過剰の硝酸を除去して結晶化を行う工
程と、 ｃ） 該結晶を希硝酸に再溶解する工程 とを具備することを特徴とする排気浄化触媒製造用ロジ
ウム含有溶液の調製方法。1. a) A solution obtained by mixing a crystal of rhodium hydroxide with a water-soluble organic acid having at least one carboxyl group and having a content of at least 0.1 mol per mol of rhodium and dissolving in nitric acid. And b) removing excess nitric acid from the solution for crystallization, and c) re-dissolving the crystals in dilute nitric acid. A method for preparing a rhodium-containing solution.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63255792A JP2732611B2 (en) | 1988-10-13 | 1988-10-13 | Method for preparing rhodium-containing solution for producing exhaust purification catalyst |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63255792A JP2732611B2 (en) | 1988-10-13 | 1988-10-13 | Method for preparing rhodium-containing solution for producing exhaust purification catalyst |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02102737A JPH02102737A (en) | 1990-04-16 |
| JP2732611B2 true JP2732611B2 (en) | 1998-03-30 |
Family
ID=17283698
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63255792A Expired - Lifetime JP2732611B2 (en) | 1988-10-13 | 1988-10-13 | Method for preparing rhodium-containing solution for producing exhaust purification catalyst |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2732611B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6174504B1 (en) * | 1996-04-01 | 2001-01-16 | Asec Manufacturing | Methods of control of nitrogen oxide and hydrocarbon emissions from small engines |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5982946A (en) * | 1982-11-02 | 1984-05-14 | Nippon Shokubai Kagaku Kogyo Co Ltd | Production of catalyst for cleaning up waste gas |
-
1988
- 1988-10-13 JP JP63255792A patent/JP2732611B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02102737A (en) | 1990-04-16 |
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