JP5418921B2 - Method for producing catalyst for direct decomposition of lower hydrocarbons - Google Patents
Method for producing catalyst for direct decomposition of lower hydrocarbons Download PDFInfo
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Description
この発明は、低級炭化水素を直接分解することにより水素およびナノ炭素を製造するアルミナ担持鉄触媒を廃アルミニウム素材・製品や廃スチール素材・製品などを原料として調製する低級炭化水素直接分解用触媒の製造方法に関するものである。 The present invention relates to a catalyst for direct decomposition of lower hydrocarbons, in which an alumina-supported iron catalyst that produces hydrogen and nanocarbon by directly cracking lower hydrocarbons is prepared from waste aluminum materials / products, waste steel materials / products, etc. as raw materials. It relates to a manufacturing method.
低級炭化水素を直接分解することにより水素およびナノ炭素を製造する触媒には、触媒金属としてニッケル、コバルト、鉄等が用いられ、担体としてはアルミナ、シリカ、チタニア、活性炭等が用いられる（例えば特許文献１参照）。触媒金属を担体に担持させるには、通常、含浸法が用いられる。この方法は触媒金属の担持率が比較的低い場合に適しており、担持率を高くしたい場合には蒸発乾固法が用いられる（例えば特許文献２参照）。
上記した含浸法は触媒成分を含む化合物溶液中に担体を浸し、その表面上に触媒成分化合物溶液を塗布したあと乾燥、熱分解を行うことで、触媒成分前駆体を担体上に適度に分散させる触媒の製造方法である。蒸発乾固法は触媒金属成分の化合物溶液に担体を浸したのち、溶媒を加熱・蒸発させたのち、熱分解をおこなうことにより固体生成物を得るものである。
For catalysts that produce hydrogen and nanocarbon by directly cracking lower hydrocarbons, nickel, cobalt, iron, etc. are used as catalyst metals, and alumina, silica, titania, activated carbon, etc. are used as carriers (for example, patents). Reference 1). In general, an impregnation method is used to support the catalyst metal on the support. This method is suitable when the loading ratio of the catalyst metal is relatively low, and when it is desired to increase the loading ratio, the evaporation to dryness method is used (see, for example, Patent Document 2).
In the above impregnation method, the catalyst component precursor is appropriately dispersed on the support by immersing the support in a compound solution containing the catalyst component, applying the catalyst component compound solution on the surface, and then drying and pyrolyzing. It is a manufacturing method of a catalyst. In the evaporation to dryness method, a solid product is obtained by immersing a carrier in a compound solution of a catalytic metal component, heating and evaporating the solvent, and then performing thermal decomposition.
触媒調製方法が上記のいずれであっても、一般に、触媒の性能は触媒材料に含まれる不純物によって悪影響を受けるので、可能な限り純度の高い触媒材料を使用する必要がある。その上で、有効な第三成分が見い出されたときにはそれを助触媒として積極的使用することになる。触媒金属の原料としては、従来、高純度の硝酸塩が用いられてきた。硝酸塩の陰イオンである硝酸イオンは熱分解により触媒から完全に除去されるので触媒成分前駆体は金属酸化物となる。したがって触媒金属の硝酸塩および担体が高純度であれば、得られる触媒成分前駆体は高純度の金属酸化物となるからである。他方、当該金属の硝酸塩の代わりに硫酸塩や塩化物を使用した場合、熱分解後にそれぞれ硫酸イオン、塩化物イオンがある程度残留し、それらは水洗を繰り返しても完全に除去することは困難なので、得られる触媒成分前駆体の純度は低くなる。一般に、触媒成分前駆体の純度が高いと触媒活性も高いことが知られており、この観点からも硝酸塩が好まれている。また担体は純度のみならず、所定の比表面積・細孔特性を持つ必要があるので、通常、専門メーカーの製品を用いる。 Regardless of the catalyst preparation method described above, in general, the performance of the catalyst is adversely affected by impurities contained in the catalyst material. Therefore, it is necessary to use a catalyst material having the highest possible purity. In addition, when an effective third component is found, it is actively used as a cocatalyst. Conventionally, high-purity nitrate has been used as a catalyst metal raw material. Since nitrate ions, which are nitrate anions, are completely removed from the catalyst by thermal decomposition, the catalyst component precursor becomes a metal oxide. Therefore, if the catalyst metal nitrate and support are of high purity, the resulting catalyst component precursor is a highly pure metal oxide. On the other hand, when sulfate or chloride is used instead of the metal nitrate, some sulfate ions and chloride ions remain after thermal decomposition, and it is difficult to completely remove them even after repeated washing. The purity of the resulting catalyst component precursor is low. In general, it is known that the catalyst activity is high when the purity of the catalyst component precursor is high. From this viewpoint, nitrate is preferred. Further, since the carrier needs to have not only purity but also a specific surface area and pore characteristics, a product of a professional manufacturer is usually used.
上記の諸点は、低級炭化水素を直接分解することにより水素およびナノ炭素を製造する触媒にもあてはまる。しかし、メタン分解反応には一般の触媒反応と異なる特徴がある。後者では、反応物も反応生成物もすべて気体であり、通常、反応後には触媒層に何も残らない。これに対して前者では、生成物として水素と炭素が得られ、炭素は固体なので触媒と一体となって反応器内に蓄積される。触媒使用時間が長いほど炭素中の触媒の割合は低下し、数ｗｔ％になることも珍しくはない。したがって、反応後に、炭素から触媒を分離することは技術的にも経済的にも容易でない。このような状況下では無回収型触媒を検討する意義が高まる。その場合、触媒コストを低く抑える観点から触媒金属成分は安価なものでなければならない。さらに触媒金属成分は炭素中に長期間とどまること、やがては廃棄されること、等を考えると低環境負荷性を考慮しなければならない。廃棄金属素材・製品を使用できればコストは下げられるが、純度の点で使用に堪えられるか疑問である。したがって触媒金属原料に廃棄金属素材・製品を使用した前例はない。 The above points also apply to catalysts that produce hydrogen and nanocarbons by directly cracking lower hydrocarbons. However, the methane decomposition reaction has characteristics different from general catalytic reactions. In the latter, both reactants and reaction products are gaseous, and usually nothing remains in the catalyst layer after the reaction. On the other hand, in the former, hydrogen and carbon are obtained as products, and since carbon is solid, it is accumulated in the reactor together with the catalyst. The longer the catalyst usage time, the lower the ratio of the catalyst in the carbon, and it is not uncommon to reach several wt%. Therefore, it is not technically or economically easy to separate the catalyst from the carbon after the reaction. Under such circumstances, the significance of examining a non-recoverable catalyst increases. In that case, the catalyst metal component must be inexpensive from the viewpoint of keeping the catalyst cost low. Furthermore, considering that the catalytic metal component stays in the carbon for a long period of time and is eventually discarded, the low environmental load must be taken into consideration. Costs can be reduced if waste metal materials and products can be used, but it is questionable whether they can be used in terms of purity. Therefore, there is no precedent for using waste metal materials and products as catalyst metal raw materials.
無回収型触媒の担体も経済性、廃棄処分時の低環境負荷性の点から吟味する必要がある。たとえばアルミナ担体の場合、廃棄アルミニウム素材・製品を使用できればコストは下げられるが、純度の点で使用に堪えられるか疑問である。 The non-recoverable catalyst carrier also needs to be examined from the viewpoint of economy and low environmental impact during disposal. For example, in the case of an alumina carrier, the cost can be reduced if a waste aluminum material or product can be used, but it is doubtful whether it can be used in terms of purity.
この発明は上記のような従来の技術の課題を解決するために成されたもので、廃棄物として排出される、アルミニウム素材・製品や鉄素材・製品を原料にしてメタン、エタン等の低級炭化水素分解触媒を製造し、触媒製造後に残る廃液をリサイクルして触媒製造時に必要な化学物質を再度製造できる製造方法を提供することを目的とする。 The present invention has been made to solve the above-mentioned problems of the prior art, and is produced as a lower carbonization of methane, ethane, etc. from aluminum materials / products and iron materials / products discharged as waste. An object of the present invention is to provide a production method capable of producing a hydrogenolysis catalyst, recycling a waste liquid remaining after the catalyst production, and producing a chemical substance necessary for the catalyst production again.
すなわち、本発明の低級炭化水素分解用触媒の製造方法のうち、請求項１記載の低級炭化水素分解用触媒の製造方法の発明は、廃鉄材を塩酸又は硝酸の水溶液に溶解して得た塩化鉄水溶液または硝酸鉄水溶液を触媒原料として使用し、水酸化アルミニウムに前記塩化鉄水溶液または前記硝酸鉄水溶液を含浸させ、これを蒸発乾固させて鉄担持アルミナの触媒前駆体を得て、前記触媒前駆体を還元して鉄担持アルミナを得ることを特徴とする。 That is, among the methods for producing a catalyst for lower hydrocarbon cracking of the present invention, the invention for the method for producing a catalyst for lower hydrocarbon cracking as claimed in claim 1 is a chloride obtained by dissolving a waste iron material in an aqueous solution of hydrochloric acid or nitric acid. Using an aqueous iron solution or an aqueous iron nitrate solution as a catalyst raw material, aluminum hydroxide is impregnated with the aqueous iron chloride solution or the aqueous iron nitrate solution, and this is evaporated to dryness to obtain an iron-supported alumina catalyst precursor. The precursor is reduced to obtain iron-supported alumina.
請求項２記載の低級炭化水素分解用触媒の製造方法の発明は、請求項１記載の発明において、前記水酸化アルミニウムは、廃アルミニウム材を塩酸水溶液に溶解して得た触媒担体原料としての塩化アルミニウム水溶液を水酸化ナトリウム又はアンモニアの水溶液で中和し沈殿させたものであることを特徴とする。
The method for producing a catalyst for cracking a lower hydrocarbon according to
請求項３記載の低級炭化水素分解用触媒の製造方法の発明は、請求項２記載の発明において、前記中和によって得られる水酸化アルミニウムを含む塩化ナトリウム水溶液又は塩化アンモニウム水溶液を濾過して水酸化アルミニウムと塩化ナトリウム水溶液又は塩化アンモニウム水溶液とに分離することを特徴とする。 According to a third aspect of the present invention, there is provided a method for producing a lower hydrocarbon cracking catalyst according to the second aspect of the present invention, wherein the aqueous sodium chloride solution or the aqueous ammonium chloride solution containing aluminum hydroxide obtained by the neutralization is filtered. It is characterized by separating into aluminum and aqueous sodium chloride solution or aqueous ammonium chloride solution.
なお、上記発明では、前記中和によって得られる塩化ナトリウム水溶液を電気分解することで中和用の水酸化ナトリウム水溶液を再生するとともに、同時に発生する塩素ガス及び水素ガスから塩化水素ガスを生成させそれを水に溶かして塩酸水溶液を再生し、再生された前記塩酸水溶液を廃アルミニウム材または廃鉄材の溶解用塩酸水溶液に使用し、再生された前記水酸化ナトリウム水溶液を前記塩化アルミニウム水溶液の中和用水溶液として使用することができる。 In the above invention, the aqueous sodium hydroxide solution for neutralization is regenerated by electrolyzing the aqueous sodium chloride solution obtained by the neutralization, and hydrogen chloride gas is generated from the chlorine gas and hydrogen gas generated at the same time. Is dissolved in water to regenerate the hydrochloric acid aqueous solution, the regenerated hydrochloric acid aqueous solution is used as a hydrochloric acid aqueous solution for dissolving waste aluminum or waste iron, and the regenerated sodium hydroxide aqueous solution is used for neutralizing the aluminum chloride aqueous solution. It can be used as an aqueous solution.
本発明では、触媒の製造コスト削減は、廃棄物として排出される、アルミニウム素材・製品と触媒金属素材・製品を使用することにより実現を図っている。
低環境負荷性の観点から、触媒金属材料として鉄を選んでいる。鉄は活性の点でニッケルよりも見劣りするが、低環境負荷性のみならず経済性においても条件に合致する。
また、経済性、低環境負荷性に優れた触媒担体としてはアルミナを選択した。廃棄アルミニウム素材・製品から製造できる可能性があり、廃棄時の環境負荷がほとんどないからである。
In the present invention, the catalyst manufacturing cost reduction is realized by using an aluminum material / product and a catalyst metal material / product discharged as waste.
From the viewpoint of low environmental impact, iron is selected as the catalytic metal material. Iron is inferior to nickel in terms of activity, but it meets the requirements not only for low environmental impact but also for economic efficiency.
In addition, alumina was selected as a catalyst carrier excellent in economy and low environmental impact. This is because there is a possibility that it can be produced from discarded aluminum materials and products, and there is almost no environmental impact during disposal.
廃棄金属素材・製品を酸溶液に溶解して触媒金属成分水溶液をつくる場合、一般に硝酸が用いられる。しかし廃棄アルミニウム素材・製品は硝酸よりも塩酸に溶けやすい。そこで両方の酸溶液が同種のものに揃えるためには廃棄金属素材・製品を塩酸溶液に溶解して触媒金属成分水溶液をつくるのが望ましく、本発明ではこの点についても十分、配慮している。廃棄アルミニウム素材・製品を酸溶液に溶かして得た溶液の中和に必要な、アンモニア水以外の安価な化学物質として水酸化ナトリウムの使用を可能としている。 Nitric acid is generally used when an aqueous solution of a catalytic metal component is prepared by dissolving a waste metal material / product in an acid solution. However, waste aluminum materials and products are more soluble in hydrochloric acid than nitric acid. Therefore, in order to prepare both acid solutions of the same type, it is desirable to dissolve a waste metal material / product in a hydrochloric acid solution to form an aqueous solution of a catalytic metal component. Sodium hydroxide can be used as an inexpensive chemical substance other than ammonia water necessary for neutralizing the solution obtained by dissolving waste aluminum materials and products in acid solution.
上記の触媒製造プロセスをクローズド型とする場合、
（１）廃鉄素材及び製品を塩酸水溶液または硝酸水溶液に溶解して塩化鉄水溶液（以下、エコ塩化鉄水溶液という）または硝酸鉄水溶液（以下、エコ硝酸鉄水溶液という）を生成させる。
（２）廃アルミニウム素材及び製品を塩酸水溶液に溶解して生成させた塩化アルミニウム水溶液（以下、エコ塩化アルミニウム水溶液という）に中和剤として水酸化ナトリウム水溶液を加えて水酸化アルミニウム（以下、エコ水酸化アルミニウム（Ａｌ（ＯＨ）３−ｃａｎ−ＮａＯＨ）という）を沈殿させる。
（３）水酸化アルミニウムとエコ塩化鉄水溶液またはエコ硝酸鉄水溶液から蒸発乾固法でアルミナ担持鉄触媒を調製する。
（４）残った母液（食塩水）を電解して水酸化ナトリウム水溶液と水素ガス、塩素ガスを生成させ、水素ガスと塩素ガスから塩化水素ガスを生成させて塩酸をつくる。
（５）上記（４）で得た水酸化ナトリウム水溶液、塩酸を循環利用する、の各工程から成る閉鎖系触媒製造プロセスを構築することができる。
When the above catalyst manufacturing process is a closed type,
(1) A waste iron material and a product are dissolved in a hydrochloric acid aqueous solution or a nitric acid aqueous solution to produce an iron chloride aqueous solution (hereinafter referred to as an eco iron chloride aqueous solution) or an iron nitrate aqueous solution (hereinafter referred to as an eco iron nitrate aqueous solution).
(2) Aluminum hydroxide (hereinafter referred to as eco water) by adding a sodium hydroxide aqueous solution as a neutralizing agent to an aluminum chloride aqueous solution (hereinafter referred to as eco aluminum chloride aqueous solution) formed by dissolving waste aluminum materials and products in hydrochloric acid aqueous solution. precipitating the aluminum oxide that (Al (OH) 3 -can- NaO H)).
(3) An alumina-supported iron catalyst is prepared from aluminum hydroxide and an aqueous ecoiron chloride solution or an aqueous ecoiron nitrate solution by evaporation to dryness.
(4) The remaining mother liquor (saline solution) is electrolyzed to produce an aqueous sodium hydroxide solution, hydrogen gas, and chlorine gas, and hydrogen chloride gas is produced from the hydrogen gas and chlorine gas to produce hydrochloric acid.
(5) It is possible to construct a closed system catalyst production process comprising the steps of recycling and using the sodium hydroxide aqueous solution and hydrochloric acid obtained in (4) above.
以上のように、この発明によれば廃鉄素材または廃鉄製品、廃アルミニウム素材または廃アルミニウム製品を触媒原料として、低級炭化水素を分解し水素とナノカーボンを生成する触媒を安価かつ親環境的に調製することができ、さらには金属廃棄物処理を兼ねたクローズド触媒製造方法を提供することできる。
特に、メタンなどの低級炭化水素分解プラントの近くで、触媒製造原料を入手して製造する場合、廃棄物を排出しない、クローズド触媒製造プロセスを導入することが理想的である。触媒を購入すれば購入者が廃棄物処理を行なう必要はないが、製造現場における廃棄物対策が必要になるのでクローズド触媒製造プロセスが有益であることに変わりはない。
As described above, according to the present invention, a catalyst for decomposing lower hydrocarbons and generating hydrogen and nanocarbons by using waste iron materials or waste iron products, waste aluminum materials or waste aluminum products as a catalyst raw material is inexpensive and environmentally friendly. In addition, it is possible to provide a method for producing a closed catalyst that also serves as a metal waste treatment.
In particular, when obtaining and producing catalyst production raw materials near a lower hydrocarbon cracking plant such as methane, it is ideal to introduce a closed catalyst production process that does not discharge waste. Purchasing the catalyst does not require the purchaser to dispose of the waste, but it does not change the benefits of the closed catalyst manufacturing process because it requires a waste countermeasure at the manufacturing site.
以下に、本発明の一実施形態を図１を参照しつつ説明する。
廃鉄素材及び製品、廃アルミニウム素材及び製品としてそれぞれ廃棄されたアルミ缶とスチール缶を使用することが考えられる。まずこれらの缶の本体に含まれる不純物の影響を検討した結果、アルミナ担持鉄触媒の鉄担持率を高くすることによってその悪影響を回避できることを見いだした。次の課題はこれらの缶を塩酸水溶液に溶解させる際にそれらの表面塗膜から溶出する不純物の触媒活性に対する影響を明らかにすることである。結果、この場合にも、アルミナ担持鉄触媒の鉄担持率を高くすれば有害不純物の影響を受けないＦｅ種の割合が増し、触媒活性減少分を相殺できることを見いだした。
An embodiment of the present invention will be described below with reference to FIG.
It is conceivable to use discarded aluminum cans and products, and discarded aluminum cans and steel cans as waste aluminum materials and products. First, as a result of examining the influence of impurities contained in the main body of these cans, it was found that the adverse effect can be avoided by increasing the iron loading ratio of the alumina-supported iron catalyst. The next task is to clarify the influence of impurities eluted from the surface coating on the catalytic activity when these cans are dissolved in aqueous hydrochloric acid. As a result, it was found that in this case as well, if the iron loading rate of the alumina-supported iron catalyst is increased, the proportion of Fe species not affected by harmful impurities increases, and the decrease in catalyst activity can be offset.
一般に、アルミニウム缶とスチール缶は外部表面が塗膜で覆われ、内部表面は樹脂フイルムで覆われている。金属材料を酸溶液に溶解させる際には、塗膜や樹脂フイルムを除去する必要がある。
上記目的を達成するためには、
（１）缶を破砕処理して破断面および剥離部から酸溶液を浸透させる方法
（２）缶を破砕せずに塗膜を削り落とし酸溶液と接触させる方法
（３）缶を機械的に圧縮減容する際に発生した塗膜亀裂部分から酸溶液を浸透させる方法、等が考えられる。破砕処理や塗膜除去には専用装置が必要であり、塗膜除去する方法では缶の底部あるいは側面に穴を開けて酸溶液が缶内部に入り込みやすいようにする必要がある。
In general, the outer surface of an aluminum can and a steel can is covered with a coating film, and the inner surface is covered with a resin film. When the metal material is dissolved in the acid solution, it is necessary to remove the coating film and the resin film.
To achieve the above objective,
(1) Method of crushing the can and infiltrating the acid solution from the fracture surface and peeled part (2) Method of scraping the coating film without crushing the can and bringing it into contact with the acid solution (3) Mechanical compression of the can A method of infiltrating the acid solution from the cracked portion of the coating film that occurs when the volume is reduced can be considered. A dedicated apparatus is required for the crushing treatment and the coating film removal. In the method of removing the coating film, it is necessary to make a hole in the bottom or side of the can so that the acid solution can easily enter the inside of the can.
本発明では（３）の方法が特に有効である。圧縮減容装置は必要であるが、減容されるため酸溶解装置に一度に投入できる缶の個数を増やすことができる、溶解熱による酸溶液温度の上昇度が大きいため缶の溶解が促進される、塗膜がほぼ連続体として残るため塗膜の回収が容易である、塗膜から酸溶液に溶出する成分濃度を最小限度に抑えることができる、等の利点がある。 In the present invention, the method (3) is particularly effective. Although a compression volume reduction device is necessary, the number of cans that can be charged into the acid dissolving device at a time can be increased because the volume is reduced, and the dissolution of the can is promoted because the degree of increase in the acid solution temperature due to the heat of dissolution is large. There are advantages such that the coating film remains as a continuous material, and that the coating film can be easily recovered, and that the component concentration eluted from the coating film into the acid solution can be minimized.
本発明では、上記のように廃アルミニウム材としては使用済みのアルミニウム缶、廃鉄材としては使用済みのスチール缶が好適であるが、本発明としては廃アルミニウム材、廃鉄材がこれらに缶に限定をされるものではなく、種々の産業分野や家庭で発生する廃材、廃製品を用いることができる。 In the present invention, as described above, used aluminum cans are suitable as waste aluminum materials, and used steel cans are suitable as waste iron materials. However, waste aluminum materials and waste iron materials are limited to these cans. The waste materials and waste products generated in various industrial fields and households can be used.
触媒金属成分水溶液を廃棄金属素材・製品から製造する場合、通常、金属を酸溶液に溶解することになる。また、アルミナ担体を廃棄アルミニウム素材・製品から製造する場合にも、通常、それを酸溶液に溶解することになる。いずれの場合にも発生する水素ガス及び反応熱を回収できる利点があるからである。この場合、両方の酸溶液が同種のものであれば好都合である。 When the catalytic metal component aqueous solution is produced from a waste metal material / product, the metal is usually dissolved in an acid solution. Also, when an alumina carrier is produced from a waste aluminum material / product, it is usually dissolved in an acid solution. This is because the hydrogen gas and reaction heat generated in any case can be recovered. In this case, it is advantageous if both acid solutions are of the same type.
好適には図１に示すように、廃アルミニウム材であるアルミニウム缶を例えば濃度５〜３５％の塩酸水溶液に溶解させることで、化１式にしめすようにアルミニウムと塩酸が反応し、塩化アルミニウムと水素ガスが生成する。この際に発生する水素ガスは、燃料電池の燃料や後述する還元処理における還元剤として使用することができ（工程１）、上記燃料電池は、後述する塩化ナトリウム水溶液の電気分解に使用する電力に変換することができる。なお、この反応は発熱反応であるため液温は次第に上昇し９０℃程度に達することもあるがあまり高い温度では塩酸ミストが発生するので好ましくない。 Preferably, as shown in FIG. 1, by dissolving an aluminum can, which is a waste aluminum material, in an aqueous hydrochloric acid solution having a concentration of 5 to 35%, for example, aluminum and hydrochloric acid react as shown in Chemical Formula 1, and aluminum chloride and Hydrogen gas is produced. The hydrogen gas generated at this time can be used as a fuel for the fuel cell or as a reducing agent in the reduction treatment described later (step 1), and the fuel cell can be used for electric power used for electrolysis of a sodium chloride aqueous solution described later. Can be converted. In addition, since this reaction is an exothermic reaction, the liquid temperature gradually rises and may reach about 90 ° C. However, a too high temperature is not preferable because hydrochloric acid mist is generated.
上記により得られる塩化アルミニウム水溶液には、図１に示すように水酸化ナトリウムを加え、溶液を中和し塩化ナトリウム溶液中で水酸化アルミニウムを沈殿させる（化２式、工程２）。この溶液をろ過、水洗し、例えば１００℃で２４時間乾燥することで水酸化アルミニウム粉末が得られ、一方で濾過の結果、塩化ナトリウム溶液が得られる（化３式、工程３）。
As shown in FIG. 1, sodium hydroxide is added to the aluminum chloride aqueous solution obtained as described above, the solution is neutralized, and aluminum hydroxide is precipitated in the sodium chloride solution (
廃棄アルミニウム素材・製品を酸溶液に溶かして得た溶液を中和してアルミナの中間原料である水酸化アルミニウムを沈殿させるような工程では、通常、中和剤としてはアンモニア水が使用される。アンモニア水に含まれるアンモニウムイオンは水洗してもなお沈殿に残留するが、熱分解工程で完全に除去可能なので、不純物の混入を嫌う触媒担体製造にはアンモニア水を使用することが考えられる。しかしアンモニアは有害物質で、臭気対策も必要なばかりか高価である。アンモニア水以外の安価な中和剤を使用できれば、これらの問題が解決するので、本発明では、好適な中和剤として水酸化ナトリウム水溶液を用いる。なお、本発明としてはアンモニア水の使用を排除するものではなく、中和剤としてアンモニア水を用いることも可能である。この場合、中和の結果として塩化アンモニウム使用液中に水酸化アルミニウムが沈殿するので、上記と同様に、これを濾過、乾燥して水酸化アルミニウム粉末（以下、エコ水酸化アルミニウム（Ａｌ（ＯＨ）３−ｃａｎ−ＮＨ３）という）と塩化アンモニウム水溶液とを得ることができる。 In the step of neutralizing a solution obtained by dissolving a waste aluminum material / product in an acid solution to precipitate aluminum hydroxide which is an intermediate raw material of alumina, ammonia water is usually used as a neutralizing agent. Ammonium ions contained in the ammonia water remain in the precipitate even after washing with water, but they can be completely removed in the thermal decomposition step. Therefore, it is conceivable to use ammonia water for the production of a catalyst carrier that does not want to contain impurities. However, ammonia is a toxic substance and not only needs countermeasures against odor but also is expensive. If an inexpensive neutralizing agent other than ammonia water can be used, these problems are solved. In the present invention, an aqueous sodium hydroxide solution is used as a suitable neutralizing agent. In the present invention, use of ammonia water is not excluded, and ammonia water can be used as a neutralizing agent. In this case, since aluminum hydroxide is precipitated in the ammonium chloride working solution as a result of neutralization, it is filtered and dried in the same manner as described above to obtain an aluminum hydroxide powder (hereinafter referred to as eco aluminum hydroxide (Al (OH)). 3 -can-NH 3) hereinafter) and can be obtained with aqueous ammonium chloride.
一方、図１に示すように、廃鉄材であるスチール缶を例えば濃度５−３５％の塩酸水溶液に溶解させることで化４式に示すように鉄と塩酸とが反応し、塩化鉄と水素ガスとが生成する（工程４）。この際に発生する水素ガスは、上記と同様に有効利用することができる。また、この反応も発熱反応であるため液温は次第に上昇し９０℃程度に達することもあるがあまり高い温度では塩酸ミストが発生するので好ましくない。 On the other hand, as shown in FIG. 1, by dissolving a steel can, which is a waste iron material, in an aqueous hydrochloric acid solution having a concentration of 5-35%, iron and hydrochloric acid react as shown in the chemical formula 4, and iron chloride and hydrogen gas are reacted. Are generated (step 4). The hydrogen gas generated at this time can be used effectively as described above. In addition, since this reaction is also an exothermic reaction, the liquid temperature gradually increases and may reach about 90 ° C., but a too high temperature is not preferable because hydrochloric acid mist is generated.
上記で得られた塩化鉄水溶液に、前述の水酸化アルミニウム粉を投入して塩化鉄水溶液を含浸させ、乾燥後、８００℃，４時間焼成することで化５式に示すように触媒前駆体（ＦｅＯ／Ａｌ２Ｏ３）が得られる（工程５）。この触媒前駆体をメタンや水素で還元をすることで、化６式に示すように、低級炭化水素分解用触媒が得られる（工程６）。なお、上記工程４では、廃鉄材を溶解させる溶液として塩酸水溶液を用いているが、本発明としては塩酸水溶液の代わりに硝酸水溶液を使用し、工程５でＦｅＣｌ３の代わりに、廃鉄素材及び製品を硝酸水溶液に溶解して得た硝酸鉄水溶液（以下、エコ硝酸鉄水溶液という）を使用することもできる。
上記各工程１〜６を経ることにより、低級炭化水素を効率よく直接分解し水素ガスと電磁波遮へい・吸収性等の機能を持つナノ炭素を生成する、鉄を担持したアルミナ触媒を廃材を用いて調製することができる。
The aqueous solution of iron chloride obtained above is charged with the above-mentioned aluminum hydroxide powder, impregnated with the aqueous solution of iron chloride, dried, and calcined at 800 ° C. for 4 hours to obtain a catalyst precursor ( FeO / Al 2 O 3 ) is obtained (step 5). By reducing the catalyst precursor with methane or hydrogen, a lower hydrocarbon decomposition catalyst is obtained as shown in the chemical formula (Step 6). In the step 4, but using a hydrochloric acid solution as a solution for dissolving the waste iron material, the present invention uses the aqueous nitric acid solution instead of aqueous hydrochloric acid, in place of the FeCl 3 in step 5, Haitetsu material and It is also possible to use an iron nitrate aqueous solution (hereinafter referred to as an eco iron nitrate aqueous solution) obtained by dissolving the product in an aqueous nitric acid solution.
By passing the above steps 1 to 6, the lower hydrocarbon is efficiently directly decomposed to produce nanocarbon having functions such as hydrogen gas and electromagnetic wave shielding / absorbing, etc., using an iron catalyst-supported alumina catalyst as a waste material Can be prepared.
なお、上記工程３で得られた塩化ナトリウム水溶液を電気分解し塩素ガス、水素ガス、水酸化ナトリウム水溶液を発生させ（化７式、工程７）、さらに化８式に示すように塩素ガスと水素ガスとを反応させて塩化水素ガスを生成させ、それを化９式に示すように水に溶かして塩酸水とし（工程８）、工程１および工程４で使用することができる。電気分解による残りの水酸化ナトリウム水溶液は工程２で使用する中和剤として再利用することができる。これにより、本触媒調製プロセスはクローズドシステムとなり有害な廃棄物を出す事がない。
The sodium chloride aqueous solution obtained in the
なお、上記実施形態では、廃アルミニウム材と廃鉄材の両方を用いる場合について説明したが、本発明としてはいずれか一方を使用して触媒金属または触媒担体を製造して触媒を得るものであってもよく、その場合においても本発明における効果は得られるものである。 In the above embodiment, the case where both the waste aluminum material and the waste iron material are used has been described. However, as the present invention, either one of them is used to produce a catalyst metal or a catalyst carrier to obtain a catalyst. Even in such a case, the effects of the present invention can be obtained.
以上、本発明について上記実施形態に基づいて説明をしたが、本発明は上記実施形態の内容に限定をされるものではなく、本発明の範囲内において当然に変更が可能である。 As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to the content of the said embodiment, Of course, it can change within the scope of the present invention.
以下、この発明の実施例を説明する。
市販アルミナ担体にそれぞれ前記実施形態の工程により得られるエコ硝酸鉄水溶液と比較材としての硝酸鉄（試薬＝ｒｅａｇｅｎｔ）水溶液を蒸発乾固法で担持（３０ｗｔ％Ｆｅ）させて２種類の触媒を調製し、メタン分解反応における活性を評価した。両触媒は共に、誘導期間が１０分程度、最高メタン転化率が３０分後に６０％程度になり、その後９０分目まで６０％程度のメタン転化率を持続した（図２）。
Examples of the present invention will be described below.
Two types of catalysts are prepared by carrying an eco-iron nitrate aqueous solution obtained by the process of the above-described embodiment and an iron nitrate (reagent = reagent) aqueous solution as a comparative material on a commercially available alumina support by evaporation to dryness (30 wt% Fe). The activity in the methane decomposition reaction was evaluated. In both catalysts, the induction period was about 10 minutes, the maximum methane conversion was about 60% after 30 minutes, and then the methane conversion was about 60% until 90 minutes (FIG. 2).
次に、硝酸鉄（試薬）水溶液をそれぞれ比較材としての市販アルミナ担体、上記実施形態で得られたエコ水酸化アルミニウム（Ａｌ（ＯＨ）３−ｃａｎ−ＮＨ３）に蒸発乾固法で担持（５０ｗｔ％Ｆｅ）させて２種類の触媒を調製し、メタン分解反応における活性を評価した（図３）。両触媒は共に、誘導期間が３０分程度、最高メタン転化率が４０分後に８０％程度になり、その後１２０分目まで７０％程度のメタン転化率を持続した。 Next, an aqueous iron nitrate (reagent) aqueous solution is supported on a commercially available alumina carrier as a comparative material and eco-aluminum hydroxide (Al (OH) 3 -can-NH 3 ) obtained in the above embodiment by evaporation to dryness ( 50 wt% Fe), two types of catalysts were prepared, and the activity in the methane decomposition reaction was evaluated (FIG. 3). In both catalysts, the induction period was about 30 minutes, the maximum methane conversion was about 80% after 40 minutes, and then the methane conversion was about 70% until 120 minutes.
また、上記実施形態で得られたエコ硝酸鉄水溶液をエコ水酸化アルミニウム（Ａｌ（ＯＨ）３−ｃａｎ−ＮＨ３）に蒸発乾固法で担持（５０ｗｔ％Ｆｅ）させて調製した触媒（Ｆｅ（ｃａｎ）／Ａｌ２Ｏ３（ｃａｎ））を用意し、同様にメタン分解反応における活性を評価した。市販アルミナ担体に硝酸鉄（試薬＝ｒｅａｇｅｎｔ）水溶液を蒸発乾固法で担持（５０ｗｔ％Ｆｅ）させて調製した触媒（Ｆｅ（ｒｅａｇｅｎｔ）／Ａｌ２Ｏ３（ＡＬＯ−７））よりも６０分ほど遅れて活性を発現したが約１２０分後には追いつき、７０％程度のメタン転化率を示した（図４）。 In addition, a catalyst (Fe (Fe (Fe)) prepared by supporting the eco-iron nitrate aqueous solution obtained in the above embodiment on eco-aluminum hydroxide (Al (OH) 3 -can-NH 3 ) by evaporation to dryness (50 wt% Fe). can) / Al 2 O 3 (can)) and the activity in the methane decomposition reaction was similarly evaluated. About 60 minutes from a catalyst (Fe (reagent) / Al 2 O 3 (ALO-7)) prepared by carrying an aqueous solution of iron nitrate (reagent = reagent) on a commercial alumina support by evaporation to dryness (50 wt% Fe). Although the activity was delayed, it caught up after about 120 minutes and showed a methane conversion rate of about 70% (FIG. 4).
なお、エコ硝酸鉄水溶液とエコ塩化アルミニウム水溶液の混合液にアンモニア水を加えて得た沈殿から調製した触媒（Ｆｅ（ｃａｎ）Ａｌ２Ｏ３（ｃａｎ−ＮＨ３）共沈法）はほとんど活性を示さなかった（図４）。 In addition, the catalyst (Fe (can) Al 2 O 3 (can-NH 3 ) coprecipitation method) prepared from a precipitate obtained by adding aqueous ammonia to a mixed solution of eco-iron nitrate aqueous solution and eco-aluminum chloride aqueous solution is almost active. Not shown (Figure 4).
また、エコ硝酸鉄水溶液をエコ水酸化アルミニウム（Ａｌ（ＯＨ）３−ｃａｎ一ＮａＯＨ）に蒸発乾固法で担持（５０ｗｔ％Ｆｅ）させて調製した触媒（Ｆｅ（ｃａｎ）／Ａｌ２Ｏ３（ｃａｎ−ＮａＯＨ））はほとんど活性を示さなかった（図５）。Ｆｅ（ｃａｎ）Ａｌ２Ｏ３（ｃａｎ−ＮＨ３）とは著しく異なる結果でありＮａが活性に悪影響を与えていることを示唆する。しかしＦｅ（ｃａｎ）／Ａｌ２Ｏ３（ｃａｎ−ＮａＯＨ）を事前に５５０℃で１時間または２時間、水素還元してからメタン分解反応を行ったところ、メタン転化率が発現するようになり、水素還元時間が長いほど誘導期が短くなる傾向が見られた。なお、Ｆｅ（ｃａｎ）Ａｌ２Ｏ３（ｃａｎ−ＮＨ３）を事前に５５０℃で１時間、水素還元してからメタン分解反応を行ったところ、誘導期間は著しく短縮され、Ｆｅ（ｒｅａｇｅｎｔ）Ａｌ２Ｏ３（ＡＬＯ−７）と同等のメタン転化率を示すようになった（図示省略）。 Further, a catalyst (Fe (can) / Al 2 O 3 (Fe (can) / Al 2 O 3 ) prepared by supporting an aqueous solution of eco iron nitrate on eco aluminum hydroxide (Al (OH) 3 -can mono-NaOH) by evaporation to dryness (50 wt% Fe). can-NaOH)) showed little activity (FIG. 5). The result is significantly different from Fe (can) Al 2 O 3 (can-NH 3 ), suggesting that Na has an adverse effect on the activity. However, when Fe (can) / Al 2 O 3 (can-NaOH) was reduced with hydrogen at 550 ° C. for 1 hour or 2 hours in advance and then subjected to a methane decomposition reaction, a methane conversion rate appeared. The longer the hydrogen reduction time, the shorter the induction period. In addition, when the methane decomposition reaction was performed after hydrogen reduction of Fe (can) Al 2 O 3 (can-NH 3 ) at 550 ° C. for 1 hour in advance, the induction period was remarkably shortened, and Fe (reagent) Al A methane conversion rate equivalent to 2 O 3 (ALO-7) was exhibited (not shown).
エコ塩化鉄水溶液をエコ水酸化アルミニウム（Ａｌ（ＯＨ）３−ｃａｎ−ＮａＯＨ）に蒸発乾固法で担持（５０ｗｔ％Ｆｅ）させて調製した触媒もやはり活性を示さなかった（図示省略）。しかしそれを事前に５５０℃で１時間水素還元してからメタン分解反応を行ったところ、メタン転化率が発現するようになった（図示省略）。 A catalyst prepared by supporting an aqueous ecoiron chloride solution on ecoaluminum hydroxide (Al (OH) 3 -can-NaOH) by evaporation to dryness (50 wt% Fe) also showed no activity (not shown). However, when the methane decomposition reaction was performed after hydrogen reduction at 550 ° C. for 1 hour in advance, a methane conversion rate was developed (not shown).
Claims (3)
水酸化アルミニウムに前記塩化鉄水溶液または前記硝酸鉄水溶液を含浸させ、これを蒸発乾固させて鉄担持アルミナの触媒前駆体を得て、
前記触媒前駆体を還元して鉄担持アルミナを得ることを特徴とする低級炭化水素直接分解用触媒の製造方法。 Using iron chloride aqueous solution or iron nitrate aqueous solution obtained by dissolving waste iron material in hydrochloric acid or nitric acid aqueous solution as catalyst raw material,
Aluminum hydroxide is impregnated with the iron chloride aqueous solution or the iron nitrate aqueous solution, and this is evaporated to dryness to obtain a catalyst precursor of iron-supported alumina,
A method for producing a catalyst for direct decomposition of a lower hydrocarbon, wherein the catalyst precursor is reduced to obtain iron-supported alumina.
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