JP2012183459A - Carbon monoxide shift catalyst, method for producing the same, method for converting carbon monoxide, and method for producing hydrogen - Google Patents
Carbon monoxide shift catalyst, method for producing the same, method for converting carbon monoxide, and method for producing hydrogen Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 171
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 135
- 229910002091 carbon monoxide Inorganic materials 0.000 title claims abstract description 134
- 238000004519 manufacturing process Methods 0.000 title claims description 40
- 238000000034 method Methods 0.000 title claims description 38
- 239000001257 hydrogen Substances 0.000 title claims description 29
- 229910052739 hydrogen Inorganic materials 0.000 title claims description 29
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims description 25
- 239000010949 copper Substances 0.000 claims abstract description 60
- 239000011701 zinc Substances 0.000 claims abstract description 59
- 229910052802 copper Inorganic materials 0.000 claims abstract description 34
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- 239000011148 porous material Substances 0.000 claims abstract description 33
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 33
- -1 copper-zinc-aluminum Chemical compound 0.000 claims abstract description 29
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 26
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- XNDZQQSKSQTQQD-UHFFFAOYSA-N 3-methylcyclohex-2-en-1-ol Chemical compound CC1=CC(O)CCC1 XNDZQQSKSQTQQD-UHFFFAOYSA-N 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
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- SXTLQDJHRPXDSB-UHFFFAOYSA-N copper;dinitrate;trihydrate Chemical compound O.O.O.[Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O SXTLQDJHRPXDSB-UHFFFAOYSA-N 0.000 description 4
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- 238000000629 steam reforming Methods 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
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- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 2
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
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- 229910017777 Cu—Al—Zn Inorganic materials 0.000 description 1
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- HXFVOUUOTHJFPX-UHFFFAOYSA-N alumane;zinc Chemical compound [AlH3].[Zn] HXFVOUUOTHJFPX-UHFFFAOYSA-N 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- Hydrogen, Water And Hydrids (AREA)
- Catalysts (AREA)
- Fuel Cell (AREA)
Abstract
Description
本発明は一酸化炭素変成触媒、一酸化炭素変成触媒の製造方法、一酸化炭素変成方法、及び水素製造方法に係り、特に、燃料電池用触媒として好適な一酸化炭素変成触媒及びその製造方法と、この一酸化炭素変成触媒を用いた一酸化炭素変成方法及び水素製造方法とに関する。 The present invention relates to a carbon monoxide conversion catalyst, a method for producing a carbon monoxide conversion catalyst, a carbon monoxide conversion method, and a hydrogen production method, and in particular, a carbon monoxide conversion catalyst suitable as a fuel cell catalyst and a method for producing the same. The present invention relates to a carbon monoxide conversion method and a hydrogen production method using the carbon monoxide conversion catalyst.
銅−亜鉛−アルミニウム触媒は、燃料電池の原料水素を炭化水素から製造する際の一酸化炭素変成反応（水性ガスシフト反応）用触媒等として好適に用いられている。
すなわち、炭化水素は水蒸気改質反応により水素に変換されるが、この水蒸気改質反応により得られる改質ガスには一酸化炭素が含まれている。この改質ガス中の一酸化炭素濃度は、１００ｐｐｍ（容積）以下、好ましくは５０ｐｐｍ以下に低減される必要があり、通常、水性ガスシフト反応によって１容積％以下に低減された後、一酸化炭素選択酸化反応によりさらに低減される。水性ガスシフト反応には、多くの場合、高温シフト触媒と低温シフト触媒とが使用される。この水性ガスシフト反応の触媒、特に低温シフト触媒として、銅−亜鉛−アルミニウム触媒が好適に使用される。
The copper-zinc-aluminum catalyst is suitably used as a catalyst for carbon monoxide shift reaction (water gas shift reaction) or the like when producing raw hydrogen for fuel cells from hydrocarbons.
That is, hydrocarbons are converted to hydrogen by a steam reforming reaction, and the reformed gas obtained by this steam reforming reaction contains carbon monoxide. The carbon monoxide concentration in the reformed gas needs to be reduced to 100 ppm (volume) or less, preferably 50 ppm or less. Usually, after being reduced to 1 volume% or less by the water gas shift reaction, the carbon monoxide selection is performed. Further reduction by oxidation reaction. In many cases, a high temperature shift catalyst and a low temperature shift catalyst are used in the water gas shift reaction. A copper-zinc-aluminum catalyst is suitably used as a catalyst for this water gas shift reaction, particularly as a low temperature shift catalyst.
この銅−亜鉛−アルミニウム触媒は、白金等の貴金属をチタニアやセリア等に坦持した貴金属触媒と比べて、低温での活性に優れている。
すなわち、この一酸化炭素変成反応（水性ガスシフト反応）は、化学平衡による制約を受け、低温になるほど一酸化炭素濃度を低減させることができる。銅−亜鉛−アルミニウム触媒は、白金等の貴金属をチタニアやセリア等に坦持した貴金属触媒と比べて比較的低温で作動することができるため、一酸化炭素濃度を１％以下にまで低減させることができる。また、この銅−亜鉛−アルミニウム触媒は、一定条件で運転を行う工業装置では長期間使用することができる。
This copper-zinc-aluminum catalyst is superior in activity at a low temperature as compared with a noble metal catalyst in which a noble metal such as platinum is supported on titania or ceria.
That is, this carbon monoxide shift reaction (water gas shift reaction) is restricted by chemical equilibrium, and the carbon monoxide concentration can be reduced as the temperature becomes lower. The copper-zinc-aluminum catalyst can operate at a relatively low temperature as compared with a noble metal catalyst in which noble metals such as platinum are supported on titania, ceria, etc., so that the carbon monoxide concentration is reduced to 1% or less. Can do. Moreover, this copper-zinc-aluminum catalyst can be used for a long time in the industrial apparatus which operate | moves on fixed conditions.
銅−亜鉛−アルミニウム触媒としては、種々のものが公知である。
特許文献１には、銅−亜鉛−アルミニウム触媒を、沈殿剤として水酸化ナトリウムを用いた共沈法により製造することが開示されている。特許文献２には、銅、亜鉛及びアルミニウムを含み、特定のＸ線回折パターンを有する触媒前駆体物質を焼成することにより、銅−亜鉛−アルミニウム触媒を製造することが開示されている。これらの銅−亜鉛−アルミニウム触媒は活性及び耐久性に優れる。
特許文献３には、ハイドロタルサイト形態のアルミニウムとハイドロタルサイトとは異なるアルミニウムとを含む触媒前駆体を用いて製造された銅−亜鉛−アルミニウム触媒は、活性が高いことが開示されている。
特許文献４には、一定の粒度分布に揃えた銅−亜鉛−アルミニウム触媒粒子をタブレット化してタブレット型触媒を製造することが開示されている。但し特許文献４には、銅−亜鉛−アルミニウム触媒粒子の製造条件の記載はない。
特許文献５には、Ｃｕ／Ｚｎ／Ａｌ系触媒に増粘剤を添加し、圧縮成型してペレット化してなるメタノール合成触媒において、平均細孔径を１２〜２５ｎｍとすることによりメタノール合成効率が向上することが開示されている。
Various copper-zinc-aluminum catalysts are known.
Patent Document 1 discloses that a copper-zinc-aluminum catalyst is produced by a coprecipitation method using sodium hydroxide as a precipitating agent. Patent Document 2 discloses that a copper-zinc-aluminum catalyst is produced by firing a catalyst precursor material containing copper, zinc and aluminum and having a specific X-ray diffraction pattern. These copper-zinc-aluminum catalysts are excellent in activity and durability.
Patent Document 3 discloses that a copper-zinc-aluminum catalyst produced using a catalyst precursor containing aluminum in the form of hydrotalcite and aluminum different from hydrotalcite has high activity.
Patent Document 4 discloses that a tablet-type catalyst is produced by tableting copper-zinc-aluminum catalyst particles having a uniform particle size distribution. However, Patent Document 4 does not describe production conditions for copper-zinc-aluminum catalyst particles.
In Patent Document 5, a methanol synthesis catalyst obtained by adding a thickener to a Cu / Zn / Al catalyst and compressing and pelletizing the methanol synthesis efficiency is improved by setting the average pore diameter to 12 to 25 nm. Is disclosed.
上記のとおり、特許文献１〜５等のような銅−亜鉛−アルミニウム触媒は、白金等の貴金属をチタニアやセリア等に坦持した貴金属触媒と比べて、低温での活性に優れているが、耐久性に劣るという問題がある。
すなわち、この銅−亜鉛−アルミニウム触媒は、燃料電池のように頻繁に起動停止を行い、温度の昇降が繰り返される条件では、水の蒸発に伴う酸化及び改質ガスによる還元が生じ、その結果銅のシンタリングによる粒成長が生じ、触媒が失活し易い。
As described above, copper-zinc-aluminum catalysts such as Patent Documents 1 to 5 are superior in activity at a low temperature as compared with noble metal catalysts in which a noble metal such as platinum is supported on titania or ceria, There is a problem of inferior durability.
That is, this copper-zinc-aluminum catalyst is frequently started and stopped as in a fuel cell, and under conditions where the temperature is repeatedly raised and lowered, oxidation due to water evaporation and reduction by the reformed gas occur. Grain growth occurs due to sintering, and the catalyst tends to be deactivated.
本発明は、燃料電池のように頻繁に起動停止を行い、温度の昇降が繰り返される条件においても、活性及び耐久性の高い一酸化炭素変成触媒（銅−亜鉛−アルミニウム触媒）及びその製造方法と、この触媒を用いた一酸化炭素変成方法及び水素製造方法とを提供することを目的とする。 The present invention relates to a carbon monoxide shift catalyst (copper-zinc-aluminum catalyst) having high activity and durability, and a method for producing the same, even under conditions where the temperature is frequently increased and decreased as in a fuel cell. Another object of the present invention is to provide a carbon monoxide conversion method and a hydrogen production method using this catalyst.
本発明者らは、上記のような状況に鑑みて鋭意検討した結果、銅、亜鉛、及びアルミニウムの含有量を特定し、かつ、各種物性（比表面積、ＣｕＯ結晶子径、嵩密度、細孔容積、及び平均細孔半径）を特定してなる一酸化炭素変成触媒が、活性及び耐久性に優れることを見出し、本発明に係る一酸化炭素変成触媒を完成させた。
また、本発明者らは、共沈法で得られたＣｕ-Ａｌ-Ｚｎ系触媒前駆体に有機化合物添加剤を含有させて成型した後、この成型体を焼成することにより、高活性な一酸化炭素変成反応用の成型触媒が得られることを見出し、本発明に係る一酸化炭素変成触媒の製造方法を完成させた。
As a result of intensive studies in view of the above situation, the present inventors have specified the contents of copper, zinc, and aluminum, and have various physical properties (specific surface area, CuO crystallite diameter, bulk density, pores) The carbon monoxide shift catalyst having a specified volume and average pore radius) was found to be excellent in activity and durability, and the carbon monoxide shift catalyst according to the present invention was completed.
In addition, the present inventors made a Cu-Al-Zn-based catalyst precursor obtained by the coprecipitation method into an organic compound additive and molded it, and then fired this molded body to obtain a highly active one. The present inventors have found that a molded catalyst for carbon oxide shift reaction can be obtained, and completed the method for producing a carbon monoxide shift catalyst according to the present invention.
すなわち、本発明は、以下の［１］〜［１４］を提供するものである。
［１］銅、亜鉛、アルミニウム及び酸素を含む銅−亜鉛−アルミニウム触媒よりなる一酸化炭素変成触媒であって、前記銅、亜鉛、及びアルミニウムを、それぞれ、ＣｕＯ、ＺｎＯ、及びＡｌ2Ｏ3に換算したときに、ＣｕＯが３０〜９０質量％、ＺｎＯが３〜３０質量％、及びＡｌ2Ｏ3が７〜６０質量％であり、
比表面積が８０〜２００ｍ2／ｇ、ＣｕＯ結晶子径が１２０Å以下、嵩密度が０．６〜１．５ｇ／ｃｍ3、細孔容積が０．３〜０．６ｃｍ3／ｇ、及び平均細孔半径が４５〜１２０Åであることを特徴とする一酸化炭素変成触媒。
［２］Ｘ線回折パターンにおいて格子面間隔ｄ（Å） ２．４４±０．０５，および２．８６±０．０５に半値幅１．０度以上のブロードなピークを有し、格子面間隔ｄ（Å） ２．４８±０．０５、２．８１±０．０５、２．６０±０．０５のいずれにもピークが存在しない［１］に記載の一酸化炭素変成触媒。
［３］銅、亜鉛及びアルミニウムを含む金属塩溶液と、沈殿剤を含有する沈殿剤含有水溶液とを共沈させて触媒前駆体を得る共沈工程と、前記触媒前駆体の洗浄工程と、前記触媒前駆体の乾燥工程と、前記触媒前駆体を成型して成型体とする成型工程と、前記成型体を焼成して一酸化炭素変成触媒とする焼成工程とを含んでおり、前記成型工程よりも前に前記沈殿物に有機化合物添加剤を含有させる添加工程を有することを特徴とする［１］又は［２］に記載の一酸化炭素変成触媒の製造方法。
［４］前記共沈工程において、前記沈殿剤としてアルカリ金属水酸化物を用い、ｐＨ８．５以上で共沈させる［３］に記載の一酸化炭素変成触媒の製造方法。
［５］前記共沈工程において、前記金属塩溶液中における金属成分の原子比が、Ｃｕ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．３〜０．９、Ｚｎ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．０５〜０．３、Ａｌ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．０７〜０．６、Ａｌ／Ｚｎ=２〜１０である［４］に記載の一酸化炭素変成触媒の製造方法。
［６］前記共沈工程において、前記金属塩溶液中における金属成分の原子比が、Ｃｕ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．３〜０．９、Ｚｎ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．０５〜０．３、Ａｌ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．０７〜０．６、Ａｌ／Ｚｎ=２〜１０であり、前記沈殿剤含有水溶液が、ＣＯ3を有する塩基性物質を含むものであり、前記金属塩溶液と前記沈殿剤含有水溶液とを、ｐＨ５〜７、温度６５℃以下で共沈させて触媒前駆体を得る［３］に記載の一酸化炭素変成触媒の製造方法。
［７］前記有機化合物添加剤が高分子系セルロース、ポリビニルアルコール、ポリメチルメタクリレート、グリセリン、でんぷん類、ゼラチン及びアルコール類の中から選ばれる１種又は２種以上である［３］〜［６］のいずれかに記載の一酸化炭素変成触媒の製造方法。
［８］前記成型が打錠成型である［３］〜［７］のいずれかに記載の一酸化炭素変成触媒の製造方法。
［９］前記成型が押出成型である［３］〜［７］のいずれかに記載の一酸化炭素変成触媒の製造方法。
［１０］無機バインダの添加を行わない［８］又は［９］に記載の一酸化炭素変［１１］［１］又は［２］に記載の一酸化炭素変成触媒を用いて、１５０〜５００℃において一酸化炭素変成反応により一酸化炭素を含む水素含有ガス中の一酸化炭素濃度を低下させる一酸化炭素変成方法。
［１２］［３］〜［１０］のいずれかに記載の一酸化炭素変成触媒の製造方法によって製造された一酸化炭素変成触媒を用いて、１５０〜５００℃において一酸化炭素変成反応により一酸化炭素を含む水素含有ガス中の一酸化炭素濃度を低下させる一酸化炭素変成方法。
［１３］［１１］又は［１２］に記載の一酸化炭素変成方法により一酸化炭素濃度を低下させた後、一酸化炭素選択酸化反応を用いないで一酸化炭素濃度を低下させる水素製造方法。
［１４］［１１］又は［１２］に記載の一酸化炭素変成方法により一酸化炭素濃度を低下させた後、一酸化炭素選択メタン化反応により一酸化炭素濃度を低下させる水素製造方法。
That is, the present invention provides the following [1] to [14].
[1] A carbon monoxide conversion catalyst comprising a copper-zinc-aluminum catalyst containing copper, zinc, aluminum and oxygen, wherein the copper, zinc and aluminum are converted into CuO, ZnO and Al 2 O 3 , respectively. when converted,
Specific surface area of 80 to 200 m 2 / g, CuO crystallite diameter of 120 mm or less, bulk density of 0.6 to 1.5 g / cm 3 , pore volume of 0.3 to 0.6 cm 3 / g, and average fineness A carbon monoxide shift catalyst having a pore radius of 45 to 120 mm.
[2] In the X-ray diffraction pattern, the lattice spacing d (回 折) has broad peaks with a half-value width of 1.0 degree or more at 2.44 ± 0.05 and 2.86 ± 0.05, and the lattice spacing is d (Å) The carbon monoxide conversion catalyst according to [1], wherein no peak exists in any of 2.48 ± 0.05, 2.81 ± 0.05, and 2.60 ± 0.05.
[3] A coprecipitation step of coprecipitation of a metal salt solution containing copper, zinc and aluminum and a precipitant-containing aqueous solution containing a precipitant to obtain a catalyst precursor, the catalyst precursor washing step, A catalyst precursor drying step, a molding step of molding the catalyst precursor to form a molded body, and a firing step of firing the molded body to form a carbon monoxide conversion catalyst. From the molding step The method for producing a carbon monoxide conversion catalyst according to [1] or [2], further comprising an addition step of adding an organic compound additive to the precipitate.
[4] The method for producing a carbon monoxide conversion catalyst according to [3], wherein in the coprecipitation step, an alkali metal hydroxide is used as the precipitating agent and coprecipitation is performed at pH 8.5 or more.
[5] In the coprecipitation step, the atomic ratio of the metal component in the metal salt solution is Cu / (Cu + Zn + Al) = 0.3 to 0.9, Zn / (Cu + Zn + Al) = The method for producing a carbon monoxide conversion catalyst according to [4], wherein 0.05 to 0.3, Al / (Cu + Zn + Al) = 0.07 to 0.6, and Al / Zn = 2 to 10.
[6] In the coprecipitation step, the atomic ratio of the metal components in the metal salt solution is Cu / (Cu + Zn + Al) = 0.3 to 0.9, Zn / (Cu + Zn + Al) = 0.05 to 0.3, Al / (Cu + Zn + Al) = 0.07 to 0.6, Al / Zn = 2 to 10, and the precipitant-containing aqueous solution is a basic substance having CO 3 The carbon monoxide conversion catalyst according to [3], wherein the catalyst precursor is obtained by coprecipitation of the metal salt solution and the precipitant-containing aqueous solution at a pH of 5 to 7 and a temperature of 65 ° C. or lower. Method.
[7] The organic compound additive is one or more selected from polymer cellulose, polyvinyl alcohol, polymethyl methacrylate, glycerin, starches, gelatin and alcohols [3] to [6] The manufacturing method of the carbon monoxide conversion catalyst in any one of these.
[8] The method for producing a carbon monoxide conversion catalyst according to any one of [3] to [7], wherein the molding is tableting molding.
[9] The method for producing a carbon monoxide conversion catalyst according to any one of [3] to [7], wherein the molding is extrusion molding.
[10] Carbon monoxide modification [11] [1] or [2] described in [8] or [9] in which no inorganic binder is added, and 150 to 500 ° C. Carbon monoxide conversion method in which the concentration of carbon monoxide in a hydrogen-containing gas containing carbon monoxide is reduced by a carbon monoxide conversion reaction.
[12] Using the carbon monoxide conversion catalyst produced by the method for producing a carbon monoxide conversion catalyst according to any one of [3] to [10], the carbon monoxide is oxidized by a carbon monoxide conversion reaction at 150 to 500 ° C. A carbon monoxide conversion method for reducing a carbon monoxide concentration in a hydrogen-containing gas containing carbon.
[13] A method for producing hydrogen, wherein the carbon monoxide concentration is lowered by the carbon monoxide conversion method according to [11] or [12], and then the carbon monoxide concentration is lowered without using a carbon monoxide selective oxidation reaction.
[14] A method for producing hydrogen, wherein the carbon monoxide concentration is reduced by a carbon monoxide selective methanation reaction after the carbon monoxide concentration is reduced by the carbon monoxide conversion method according to [11] or [12].
本発明によると、細孔容積、細孔径が大きい上、ＣｕＯ結晶子径が小さく、高活性かつ耐久性を示す一酸化炭素変成触媒を得ることができる。 According to the present invention, it is possible to obtain a carbon monoxide conversion catalyst having a large pore volume and a large pore diameter, a small CuO crystallite diameter, and high activity and durability.
以下、本発明を詳細に説明する。
＜一酸化炭素変成触媒の製造方法＞
本発明の一酸化炭素変成触媒の製造方法は、銅、亜鉛及びアルミニウムを含む金属塩溶液と、沈殿剤を含有する沈殿剤含有水溶液とを共沈させて触媒前駆体を得る共沈工程と、前記触媒前駆体の洗浄工程と、前記触媒前駆体の乾燥工程と、前記触媒前駆体を成型して成型体とする成型工程と、前記成型体を焼成して一酸化炭素変成触媒とする焼成工程とを含んでおり、前記成型工程よりも前に前記沈殿物に有機化合物添加剤を含有させる（あるいは，添加する）添加工程を有することを特徴とする。
以下、各工程について詳細に説明する。
Hereinafter, the present invention will be described in detail.
<Method for producing carbon monoxide conversion catalyst>
The method for producing a carbon monoxide conversion catalyst of the present invention comprises a coprecipitation step of coprecipitation of a metal salt solution containing copper, zinc and aluminum and a precipitant-containing aqueous solution containing a precipitant to obtain a catalyst precursor; Cleaning step of the catalyst precursor, drying step of the catalyst precursor, molding step of molding the catalyst precursor to form a molded body, and firing step of firing the molded body to form a carbon monoxide conversion catalyst And having an addition step of adding (or adding) an organic compound additive to the precipitate prior to the molding step.
Hereinafter, each step will be described in detail.
［共沈工程］
本工程では、銅、亜鉛及びアルミニウムを含む金属塩溶液と、沈殿剤を含有する沈殿剤含有水溶液とを共沈させて触媒前駆体を得る。
[Co-precipitation process]
In this step, a catalyst precursor is obtained by coprecipitation of a metal salt solution containing copper, zinc and aluminum and a precipitant-containing aqueous solution containing a precipitant.
（金属塩溶液）
銅及び亜鉛の塩種としては、硝酸塩や酢酸塩が好ましい。アルミニウム塩は硝酸塩、水酸化物、アルミン酸ナトリウム、プソイドベーマイトなどを用いることができ、硝酸塩、アルミン酸ナトリウムが好ましい。
(Metal salt solution)
As salt types of copper and zinc, nitrates and acetates are preferable. As the aluminum salt, nitrate, hydroxide, sodium aluminate, pseudoboehmite and the like can be used, and nitrate and sodium aluminate are preferable.
前記金属塩溶液中の銅、亜鉛及びアルミニウムの原子比としては、Ｃｕ／（Ｃｕ＋Ｚｎ＋Ａｌ）が好ましくは０．３〜０．９、より好ましくは０．４５〜０．７、更に好ましくは０．６５〜０．７である。また、Ｚｎ／（Ｃｕ＋Ｚｎ＋Ａｌ）は好ましくは０．０５〜０．３０、より好ましくは０．０７〜０．２、更に好ましくは０．０９〜０．１である。Ａｌ／（Ｃｕ＋Ｚｎ＋Ａｌ）は好ましくは０．０７〜０．６、より好ましくは０．２〜０．４、更に好ましくは０．２〜０．２５である。Ａｌ／Ｚｎは好ましくは２〜１０、より好ましくは２．２〜３．５、更に好ましくは２．２〜２．５である。
金属の原子比を上記のような範囲とすると、この触媒前駆体を焼成したときに、耐水熱性に優れるＺｎＡｌ2Ｏ4が生成する。これにより、触媒の耐久性（特に起動・停止を繰り返して使用する状態で、触媒が実用上満足できる活性を維持できる時間）の低下が防止されると共に、亜鉛原子が多すぎてジンサイト（ｚｉｎｃｉｔｅ、ＺｎＯ）等が生成することが防止される。その結果、触媒の耐久性が向上する。また、ジンサイトのシンタリングは銅のシンタリングを促進し触媒活性の低下を引き起こすが、これが防止され、触媒活性に優れる。
The atomic ratio of copper, zinc and aluminum in the metal salt solution is preferably Cu / (Cu + Zn + Al), preferably 0.3 to 0.9, more preferably 0.45 to 0.7, and still more preferably 0.65. ~ 0.7. Further, Zn / (Cu + Zn + Al) is preferably 0.05 to 0.30, more preferably 0.07 to 0.2, and still more preferably 0.09 to 0.1. Al / (Cu + Zn + Al) is preferably 0.07 to 0.6, more preferably 0.2 to 0.4, and still more preferably 0.2 to 0.25. Al / Zn is preferably 2 to 10, more preferably 2.2 to 3.5, and still more preferably 2.2 to 2.5.
When the atomic ratio of the metal is in the above range, ZnAl 2 O 4 having excellent hydrothermal resistance is produced when the catalyst precursor is fired. This prevents a decrease in the durability of the catalyst (especially, the time during which the catalyst can maintain a practically satisfactory activity in a state where it is repeatedly started and stopped), and there are too many zinc atoms and a zincite (zincite). , ZnO) and the like are prevented from being generated. As a result, the durability of the catalyst is improved. In addition, the zincite sintering promotes copper sintering and causes a decrease in catalytic activity, but this is prevented and the catalytic activity is excellent.
（沈殿剤）
上記沈殿剤としては、好ましくはアルカリ金属水酸化物及び/又はＣＯ3を有する塩基性物質が挙げられる。
（１） アルカリ金属水酸化物
アルカリ金属水酸化物としては、好ましくは水酸化ナトリウムが用いられる。
このアルカリ金属水酸化物と上記金属塩溶液との共沈は、好ましくはｐＨ８．５以上、更に好ましくは８．５〜１１とする。ｐＨをこの範囲内とすることにより、十分な活性と耐久性を有する触媒を得ることが可能となる。
このアルカリ金属水酸化物と上記金属塩溶液との共沈は、好ましくは０〜９０℃、より好ましくは１０〜８０℃に維持する。温度をこの範囲内とすることにより、十分な活性と耐久性を有する触媒を得ることが可能となる。沈殿物は、熟成させてもよく、熟成させなくてもよい。
(Precipitating agent)
The precipitant is preferably a basic substance having an alkali metal hydroxide and / or CO 3 .
(1) Alkali metal hydroxide As the alkali metal hydroxide, sodium hydroxide is preferably used.
The coprecipitation of the alkali metal hydroxide and the metal salt solution is preferably pH 8.5 or more, more preferably 8.5 to 11. By setting the pH within this range, a catalyst having sufficient activity and durability can be obtained.
The coprecipitation of the alkali metal hydroxide and the metal salt solution is preferably maintained at 0 to 90 ° C, more preferably 10 to 80 ° C. By setting the temperature within this range, a catalyst having sufficient activity and durability can be obtained. The precipitate may be aged or may not be aged.
このように沈殿剤としてアルカリ金属水酸化物を用いて得られた触媒前駆体は、銅、亜鉛及びアルミニウムを含み、spertiniite（Ｃｕ（ＯＨ）2）のＸ線回折パターンに類似したブロードなＸ線回折パターンを示す物質を有することが好ましい。
すなわち、この触媒前駆体は、Ｘ線回折パターンが格子面間隔ｄ（Å）５．３±０．５、３．７３±０．３、２．６３±０．２、２．２６±０．２及び１．７１±０．１にピークを有することが好ましい。一方、spertiniite（Ｃｕ（ＯＨ）2）のＸ線回折パターンは、以下に回折線を有する。
ｄ＝２．６３、ｄ＝３．７３、ｄ＝５．２９、ｄ＝２．２６６、ｄ＝１．７１８、ｄ＝２．５０、ｄ＝２．３６１
The catalyst precursor thus obtained using an alkali metal hydroxide as a precipitant contains copper, zinc and aluminum, and has a broad X-ray similar to the X-ray diffraction pattern of spertiniite (Cu (OH) 2 ). It is preferable to have a substance exhibiting a diffraction pattern.
That is, this catalyst precursor has an X-ray diffraction pattern with a lattice spacing d (Å) 5.3 ± 0.5, 3.73 ± 0.3, 2.63 ± 0.2, 2.26 ± 0. It is preferable to have peaks at 2 and 1.71 ± 0.1. On the other hand, the X-ray diffraction pattern of spertiniite (Cu (OH) 2 ) has diffraction lines below.
d = 2.63, d = 3.73, d = 5.29, d = 2.266, d = 1.718, d = 2.50, d = 2.361
なお、この触媒前駆体は、上記のspertiniiteに類似するＸ線回折ピークの他に、格子面間隔ｄ（Å）８．７±０．５、７．６０±０．５及び５．３±０．５にピークを有していてもよい。この場合、格子面間隔ｄ（Å）８．７±０．５及び７．６０±０．５のピーク強度が５．３±０．５のピーク強度よりも大きいピークを有しないことが好ましい。この格子面間隔ｄ（Å）８．７±０．５にピークを有する物質はscarbroiteであり、格子面間隔ｄ（Å）７．６０±０．５にピークを有する物質はハイドロタルサイト（hydrotalcite）であり、格子面間隔ｄ（Å）５．３±０．５にピークを有する物質はspertiniiteである。このようにspertiniiteを多く含み、且つscarbroite及びハイドロタルサイトのような不純物の少ない触媒前駆体を用いることにより、活性の高い一酸化炭素変成触媒を得ることが容易となる。 In addition to the X-ray diffraction peak similar to the above-mentioned spertiniite, this catalyst precursor has a lattice plane distance d (Å) of 8.7 ± 0.5, 7.60 ± 0.5, and 5.3 ± 0. .5 may have a peak. In this case, it is preferable that the peak intensities of the lattice spacing d (Å) 8.7 ± 0.5 and 7.60 ± 0.5 do not have peaks larger than the peak intensities of 5.3 ± 0.5. The substance having a peak at the lattice spacing d (Å) 8.7 ± 0.5 is scarbroite, and the substance having a peak at the lattice spacing d (Å) 7.60 ± 0.5 is hydrotalcite. And a substance having a peak at a lattice spacing d (Å) 5.3 ± 0.5 is spertiniite. Thus, it becomes easy to obtain a carbon monoxide conversion catalyst having high activity by using a catalyst precursor containing a large amount of spertiniite and having few impurities such as scarbroite and hydrotalcite.
（２） ＣＯ3を有する塩基性物質
ＣＯ3を有する塩基性物質としては、好ましくは炭酸ナトリウムが用いられる。
沈殿剤としてこのＣＯ3を有する塩基性物質を用い、且つ上記金属塩溶液中の銅、亜鉛及びアルミニウムの原子比を上記範囲内として共沈させて得た触媒前駆体は、MalachiteとHydrotalciteとからなるが、Malachiteに富み、Hydrotalciteが２５質量％以下の銅、亜鉛、アルミニウム組成物となる。
Malachiteは通常Ｃｕ2（ＣＯ3）（ＯＨ）2であらわされるが、Ｃｕの一部がＺｎに置き換わった構造をとることができる。この構造は、Zincian-Malachite[（Ｃｕ,Ｚｎ）2（ＯＨ）2ＣＯ3]、あるいはRosasiteといわれ、格子面間隔（Å） ｄ＝２．８６Å，３．６９Å，５．０５Å，５．９９Å，２．７８Å，２．５２Å，２．４８Å，１．５９Å，３．６７Å，２．４２ÅにＸ線回折ピークを有する。
(2) Basic substance having CO 3 As the basic substance having CO 3 , sodium carbonate is preferably used.
The catalyst precursor obtained by using this basic substance having CO 3 as a precipitating agent and coprecipitating the atomic ratio of copper, zinc and aluminum in the above metal salt solution within the above range is obtained from Malachite and Hydrotalcite. However, it is rich in Malachite and becomes a copper, zinc and aluminum composition having a Hydrotalcite content of 25% by mass or less.
Malachite is usually represented by Cu 2 (CO 3 ) (OH) 2 , but can take a structure in which a part of Cu is replaced by Zn. This structure is called Zincian-Malachite [(Cu, Zn) 2 (OH) 2 CO 3 ], or Rosasite, and the lattice spacing (Å) d = 2.86Å, 3.69Å, 5.05Å, 5.99Å , 2.78 Å, 2.52 Å, 2.48 Å, 1.59 Å, 3.67 Å and 2.42 Å have X-ray diffraction peaks.
この共沈による触媒前駆体の形成においては、適度に攪拌しながら、ｐＨ５〜７、６５℃以下で実施することが好ましい。攪拌が激しすぎると、Hydrotalciteの割合が増加し、Malachiteの割合が低下し、好ましくない。共沈温度が６５℃を超えると、Hydrotalcite量が増えすぎたり、一部ＺｎＯが生成する。沈殿物は２時間以上熟成させることが好ましい。 The formation of the catalyst precursor by this coprecipitation is preferably carried out at a pH of 5 to 7 and 65 ° C. or lower with moderate stirring. Excessive stirring is not preferable because the ratio of Hydrotalcite increases and the ratio of Malachite decreases. When the coprecipitation temperature exceeds 65 ° C., the amount of Hydrotalcite increases excessively or a part of ZnO is generated. The precipitate is preferably aged for 2 hours or longer.
なお、上記金属塩溶液と上記沈殿剤とを混合して触媒前駆体を共沈させる場合には、これらの溶液のいずれか一方を撹拌しながらもう一方を混合してもよい。また、それぞれの溶液をポンプなどで同時に供給して混合してもよい。また、沈殿物は２時間以上熟成させることが好ましい。 In addition, when mixing the said metal salt solution and the said precipitant and coprecipitating a catalyst precursor, you may mix the other, stirring either one of these solutions. Moreover, you may supply and mix each solution with a pump etc. simultaneously. The precipitate is preferably aged for 2 hours or more.
［洗浄工程］
上記共沈工程で得られた触媒前駆体は、ゲル状のスラリーとなる。この触媒前駆体を、洗浄及び濾過する。このように洗浄及び濾過すると、微粒子間に水を多く含んで膨潤したケーキが得られる。
[Washing process]
The catalyst precursor obtained in the coprecipitation step becomes a gel slurry. The catalyst precursor is washed and filtered. By washing and filtering in this way, a swollen cake containing a large amount of water between the fine particles is obtained.
［乾燥工程］
次いで、この触媒前駆体のケーキを乾燥する。この乾燥条件は、後述する成型工程での成型方法に応じて適宜設定される。
押出成型を行う場合には、この触媒前駆体のケーキを押出成型に適した水分量になるまで乾燥させる。例えば室温〜１００℃程度で良好な可塑性が得られる程度まで水分を除けばよい。なお、この押出成型を行う場合には、押出成型後の成型体を、好ましくは８０〜２００℃で再度乾燥させてから、後述する焼成工程を行うことが好ましい。
打錠成型を行う場合には、この触媒前駆体のケーキを好ましくは８０〜２００℃で十分に乾燥させる。
[Drying process]
The catalyst precursor cake is then dried. This drying condition is appropriately set according to a molding method in a molding process described later.
In the case of performing extrusion molding, the cake of the catalyst precursor is dried until the moisture content is suitable for extrusion molding. For example, the moisture may be removed to such an extent that good plasticity is obtained at room temperature to about 100 ° C. In addition, when performing this extrusion molding, it is preferable to perform the baking process mentioned later, after drying the molded object after extrusion molding again preferably at 80-200 degreeC.
When tableting is performed, the catalyst precursor cake is preferably sufficiently dried at 80 to 200 ° C.
［添加工程］
後述する成型工程の前に、前記触媒前駆体に有機化合物添加剤を含有させる。この添加工程は、洗浄工程内の洗浄中、洗浄後、又は濾過後に実施することが好ましい。これにより、有機化合物添加剤を触媒前駆体に対して均一に含有させることができる。
但し、洗浄工程中のほか、洗浄工程前、洗浄工程と乾燥工程の間、乾燥工程中、及び乾燥工程後のいずれのタイミングで添加工程を実施してもよく、これらの複数のタイミングで添加工程を実施してもよい。
[Addition process]
Prior to the molding step described later, an organic compound additive is contained in the catalyst precursor. This addition step is preferably performed during the cleaning in the cleaning step, after the cleaning, or after the filtration. Thereby, an organic compound additive can be uniformly contained with respect to the catalyst precursor.
However, the addition process may be performed at any timing before or after the cleaning process, between the cleaning process and the drying process, during the drying process, and after the drying process. May be implemented.
この有機化合物添加剤としては、セルロース系高分子、ポリビニルアルコール、ポリメチルメタクリレート、グリセリン、でんぷん類、ゼラチン、アルコール類が使用できる。特に高分子系セルロース、ポリビニルアルコールが好ましい。高分子系セルロースとしてはメチルセルロース類、ヒドロキシエチルセルロース類、ヒドロキシプロピルセルロース類あるいはカルボキシメチルセルロース類が使用できる。
有機化合物添加剤の添加量は、触媒当たり０．５〜５質量％が好ましい。０．５質量％以上であると、添加による触媒活性向上効果が良好に発現する。１０質量％以下であると、焼成の際の発熱が大きくなることによる銅成分の凝集が防止される。
Cellulose polymers, polyvinyl alcohol, polymethyl methacrylate, glycerin, starches, gelatin, and alcohols can be used as the organic compound additive. High molecular weight cellulose and polyvinyl alcohol are particularly preferable. As the high molecular weight cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, or carboxymethyl cellulose can be used.
The addition amount of the organic compound additive is preferably 0.5 to 5% by mass per catalyst. When the amount is 0.5% by mass or more, the effect of improving the catalytic activity due to the addition is exhibited well. When the content is 10% by mass or less, aggregation of copper components due to an increase in heat generation during firing is prevented.
なお、この有機化合物添加剤のほかに、無機バインダを触媒前駆体に含有させてもよいが、触媒活性が低下することがあるので含有させないことが好ましい。これにより、相対的に有機化合物添加剤の添加量を多くすることができ、触媒の活性の向上を図ることができる。無機バインダとしては、シリカ、アルミナ、ジルコニア、水酸化アルミニウム、二酸化ケイ素、水ガラス等が挙げられる。 In addition to this organic compound additive, an inorganic binder may be included in the catalyst precursor, but it is preferable not to include it because the catalyst activity may be reduced. Thereby, the addition amount of the organic compound additive can be relatively increased, and the activity of the catalyst can be improved. Examples of the inorganic binder include silica, alumina, zirconia, aluminum hydroxide, silicon dioxide, and water glass.
［成型工程］
次いで、上記のとおり有機化合物添加剤を含有させた触媒前駆体を成型する。
成型方法としては、押出成型、転動造粒、打錠成型など特に制限はないが、成型の容易性から、押出成型及び打錠成型が好ましい。
[Molding process]
Next, the catalyst precursor containing the organic compound additive is molded as described above.
The molding method is not particularly limited, such as extrusion molding, rolling granulation, and tableting molding, but extrusion molding and tableting molding are preferable from the viewpoint of ease of molding.
押出成型の場合は、上述のとおり触媒前駆体を押出成型に適した水分量になるまで乾燥させると共に有機化合物添加剤を添加した後に、常法により押出成型を行う。押出成型後の成型体は、上述のとおり好ましくは８０〜２００℃で十分に乾燥させる。
打錠成型の場合は、乾燥後の触媒前駆体を、０．０５〜２ｍｍ程度の大きさに造粒又は粉砕して粉体又は顆粒とし、この粉体又は顆粒を打錠成型することが好ましい。例えば、乾燥後の触媒前駆体を粉砕して成型用の孔（金型）に充填し、圧壊強度が２０〜４０Ｎの範囲になるよう打錠成型することにより、この成型体を焼成してなる焼成体の嵩密度が０．６〜２．０ｇ／ｃｍ3という適切な範囲内になりやすい。通常、打錠成型圧力を高くすると、圧壊強度は高くなり、成型触媒の嵩密度は大きくなるが、あまり高くすると触媒性能が低下することがあるので、圧壊強度が２０〜４０Ｎ程度になるよう打錠成型するのが好ましい。
In the case of extrusion molding, as described above, the catalyst precursor is dried to a moisture content suitable for extrusion molding, and after adding an organic compound additive, extrusion molding is performed by a conventional method. The molded body after extrusion molding is preferably sufficiently dried at 80 to 200 ° C. as described above.
In the case of tableting molding, it is preferable to granulate or pulverize the catalyst precursor after drying to a size of about 0.05 to 2 mm to form a powder or granule, and to compress this powder or granule. . For example, the dried catalyst precursor is pulverized and filled into molding holes (molds), and the molded body is fired by tableting so that the crushing strength is in the range of 20 to 40 N. The bulk density of the fired body tends to be within an appropriate range of 0.6 to 2.0 g / cm 3 . Normally, when the tableting molding pressure is increased, the crushing strength is increased and the bulk density of the molded catalyst is increased. However, if the molding pressure is too high, the catalyst performance may be lowered. Tableting is preferred.
［焼成工程］
本工程では、上記の成型工程で得られた成型体を焼成する。この焼成工程により、触媒前駆体中に含有させた有機化合物添加剤は除去される。このようにして、所定の成型形状を有する一酸化炭素変成触媒（一酸化炭素変成反応用の成型触媒）が得られる。
焼成条件は特に制限はないが、２００〜６５０℃程度で０．１時間〜１０時間程度実施すれば、所望の物性を有する一酸化炭素変成触媒が得られる。すなわち、後述するとおり、比表面積が８０〜２００ｍ2／ｇ、ＣｕＯ結晶子径が１２０Å以下、嵩密度０．６〜１．５ｇ／ｃｍ3、細孔容積０．３０〜０．６０ｃｍ3／ｇ、平均細孔半径４５〜１２０Åであり、亜鉛の状態がＺｎＯではなく亜鉛アルミニウムスピネル（ＺｎＡｌ2Ｏ4）の状態で存在する触媒が得られる。６５０℃以下で焼成すると、ＣｕＯ結晶子及び亜鉛アルミネートスピネル結晶子の径の増大が防止される。
[Baking process]
In this step, the molded body obtained in the above molding step is fired. By this calcination step, the organic compound additive contained in the catalyst precursor is removed. In this way, a carbon monoxide shift catalyst having a predetermined molded shape (a molded catalyst for carbon monoxide shift reaction) is obtained.
The calcining conditions are not particularly limited, but a carbon monoxide shift catalyst having desired physical properties can be obtained by carrying out the reaction at about 200 to 650 ° C. for about 0.1 to 10 hours. That is, as described later, the specific surface area is 80 to 200 m 2 / g, the CuO crystallite diameter is 120 mm or less, the bulk density is 0.6 to 1.5 g / cm 3 , and the pore volume is 0.30 to 0.60 cm 3 / g. Thus, a catalyst having an average pore radius of 45 to 120 mm and having a zinc state of zinc aluminum spinel (ZnAl 2 O 4 ) instead of ZnO is obtained. When fired at 650 ° C. or lower, an increase in the diameters of the CuO crystallite and the zinc aluminate spinel crystallite is prevented.
上記の製造方法によって得られる一酸化炭素変成触媒にあっては、活性の高い触媒となる。すなわち、Ｃｕ系触媒は、成型及び焼成によってＣｕＯが凝集して大きくなり、活性低下の原因となる。例えば、特許文献１，２のような、アルカリ金属水酸化物で共沈させて得られる触媒にあっては、大きい比表面積を有する特徴があり、粉末での触媒性能は優れているものの、成型すると細孔径及び細孔容量が小さくなり、また、乾燥、焼成及び成型によりＣｕＯ結晶子が大きくなり、十分な触媒活性が得られなかった。これに対して上記製造方法では、触媒前駆体中に有機化合物添加剤が含有されている状態で、成型工程及び焼成工程の両工程を実施する。本方法には二つの優れた効果があることが見出された。銅系触媒は成型や焼成において銅が凝集しやすいが、この有機化合物添加剤の存在により、成型や焼成においても凝集が抑制され、高度に分散した結晶サイズの細かいＣｕＯ粒子を有する高活性な触媒が得られる。また、成型段階で有機化合物添加剤が含有され、続く焼成段階で有機化合物添加剤が燃焼除去されるため、大きい細孔容積と細孔径が形成される。その結果、触媒の内部では、反応の活性点が増えると共に、反応物質がスムーズに拡散するため、一酸化炭素変成反応性が向上する。本方法は水酸化ナトリウム等のアルカリ金属水酸化物を用いた場合だけでなく、銅系触媒全般に本実施の形態に係る一酸化炭素触媒の製造方法が有効である。 The carbon monoxide shift catalyst obtained by the above production method is a highly active catalyst. That is, in the Cu-based catalyst, CuO aggregates and becomes large due to molding and firing, causing a decrease in activity. For example, a catalyst obtained by coprecipitation with an alkali metal hydroxide, such as Patent Documents 1 and 2, has a characteristic of having a large specific surface area, and has excellent catalytic performance in powder, but is molded. As a result, the pore diameter and pore volume were reduced, and the CuO crystallites were increased by drying, firing and molding, and sufficient catalytic activity was not obtained. On the other hand, in the said manufacturing method, both a shaping | molding process and a baking process are implemented in the state in which the organic compound additive is contained in the catalyst precursor. The method has been found to have two excellent effects. Copper-based catalysts are prone to agglomeration of copper during molding and firing, but the presence of this organic compound additive prevents aggregation during molding and firing and is a highly active catalyst having highly dispersed and finely-divided CuO particles with fine crystal size. Is obtained. Further, since the organic compound additive is contained in the molding stage and the organic compound additive is burned and removed in the subsequent firing stage, a large pore volume and pore diameter are formed. As a result, the active sites of the reaction increase inside the catalyst, and the reactants diffuse smoothly, so that the carbon monoxide shift reactivity is improved. This method is effective not only in the case of using an alkali metal hydroxide such as sodium hydroxide, but also in the method for producing the carbon monoxide catalyst according to the present embodiment for all copper catalysts.
＜一酸化炭素変成触媒＞
本実施の形態に係る一酸化炭素変成触媒は、銅、亜鉛、アルミニウム及び酸素を含む銅−亜鉛−アルミニウム触媒よりなる一酸化炭素変成触媒であって、前記銅、亜鉛、及びアルミニウムを、それぞれ、ＣｕＯ、ＺｎＯ、及びＡｌ2Ｏ3に換算したときに、ＣｕＯが３０〜９０質量％、ＺｎＯが３〜３０質量％、及びＡｌ2Ｏ3が７〜６０質量％であり、比表面積が８０〜２００ｍ2／ｇ、ＣｕＯ結晶子径が１２０Å以下、嵩密度が０．６〜１．５ｇ／ｃｍ3、細孔容積が０．３〜０．６ｃｍ3／ｇ、及び平均細孔半径が４５〜１２０Åであることを特徴とするものである。この一酸化炭素変成触媒は、上記製造方法によって製造することができる。
<Carbon monoxide conversion catalyst>
The carbon monoxide conversion catalyst according to the present embodiment is a carbon monoxide conversion catalyst composed of a copper-zinc-aluminum catalyst containing copper, zinc, aluminum, and oxygen. When converted to CuO, ZnO, and Al 2 O 3 , CuO is 30 to 90% by mass, ZnO is 3 to 30% by mass, and Al 2 O 3 is 7 to 60% by mass, and the specific surface area is 80 to 80%. 200 m 2 / g, CuO crystallite diameter of 120 mm or less, bulk density of 0.6 to 1.5 g / cm 3 , pore volume of 0.3 to 0.6 cm 3 / g, and average pore radius of 45 to 45 It is characterized by being 120 mm. This carbon monoxide shift catalyst can be produced by the above production method.
銅がＣｕＯ換算で３０〜９０質量％の下限値以上であると、活性種の銅原子が多くて触媒活性が向上し、上限値以下であると、相対的に亜鉛原子、アルミニウム原子が多くなるため、触媒の耐久性（特に起動・停止を繰り返して使用する状態で、触媒が実用上満足できる活性を維持できる時間。以下、単に耐久性と呼ぶ場合もある）が向上する。銅はＣｕＯ換算で、好ましくは５０〜８５質量％であり、更に好ましくは７０〜７５質量％である。
亜鉛がＺｎＯ換算で３〜３０質量％の下限値以上であると、亜鉛原子が多くなることで触媒の活性が向上し、上限値以下であると、触媒の耐久性が向上する。亜鉛はＺｎＯ換算で、好ましくは５〜１０質量％であり、更に好ましくは８〜１０質量％である。
アルミニウムがＡｌ2Ｏ3換算で７〜６０質量％の下限値以上であると、触媒強度が向上し、また触媒の耐久性が向上する。また、上限値以下であると、相対的に銅原子が多くなって触媒活性が向上する。アルミニウムはＡｌ2Ｏ3換算で、好ましくは１０〜４０質量％であり、更に好ましくは１２〜１４質量％である。
If the copper is 30% to 90% by mass or less in terms of CuO, the active species has many copper atoms and the catalytic activity is improved, and if the copper is below the upper limit, zinc atoms and aluminum atoms are relatively increased. Therefore, the durability of the catalyst (especially the time during which the catalyst can maintain a practically satisfactory activity in a state where it is repeatedly started and stopped is used. Hereinafter, it may be simply referred to as durability) is improved. Copper is preferably 50 to 85% by mass, and more preferably 70 to 75% by mass in terms of CuO.
When the zinc content is 3-30% by mass or less in terms of ZnO, the activity of the catalyst is improved by increasing the number of zinc atoms, and when the zinc content is less than the upper limit value, the durability of the catalyst is improved. Zinc is preferably 5 to 10% by mass and more preferably 8 to 10% by mass in terms of ZnO.
When the aluminum content is 7 to 60% by mass or more in terms of Al 2 O 3 , the catalyst strength is improved and the durability of the catalyst is improved. On the other hand, if it is not more than the upper limit value, the number of copper atoms is relatively increased and the catalytic activity is improved. Aluminum is preferably 10 to 40% by mass, more preferably 12 to 14% by mass in terms of Al 2 O 3 .
比表面積が８０〜２００ｍ2／ｇの範囲内であると、触媒活性が向上し、銅のシンタリング抑制効果も向上する。この比表面積は、好ましくは９０〜１４０ｍ2／ｇであり、更に好ましくは１００〜１３０ｍ2／ｇである。 When the specific surface area is in the range of 80 to 200 m 2 / g, the catalytic activity is improved and the copper sintering suppression effect is also improved. This specific surface area is preferably 90 to 140 m 2 / g, more preferably 100 to 130 m 2 / g.
ＣｕＯの結晶子径が１２０Å以下であると、反応に有効な銅の活性点数が多くなり、活性が向上する。ＣｕＯの結晶子径は、好ましくは１００Å以下であり、更に好ましくは８０Å以下である。 When the crystallite diameter of CuO is 120 mm or less, the number of active points of copper effective for the reaction increases and the activity is improved. The crystallite diameter of CuO is preferably 100 mm or less, and more preferably 80 mm or less.
嵩密度が０．６〜１．５ｇ／ｃｍ3の下限値以上であると活性が高くなり、上限値以下であると強度が高くなる。嵩密度がこの範囲内であると、この触媒を収容する反応器も小さくてすみ、家庭用燃料電池や燃料電池車に搭載するコンパクトな改質システムが可能となる。この嵩密度は、好ましくは０．７〜１．３ｇ／ｃｍ3であり、更に好ましくは１．０〜１．３ｇ／ｃｍ3である。 When the bulk density is not less than the lower limit of 0.6 to 1.5 g / cm 3, the activity is increased, and when it is not more than the upper limit, the strength is increased. If the bulk density is within this range, the reactor containing this catalyst can be small, and a compact reforming system mounted on a domestic fuel cell or a fuel cell vehicle can be realized. This bulk density is preferably 0.7 to 1.3 g / cm 3 , more preferably 1.0 to 1.3 g / cm 3 .
この一酸化炭素変成触媒は、細孔容積が０．３〜０．６ｃｍ3／ｇである。細孔容積が下限値以上であると、触媒内部への一酸化炭素の拡散速度が速くなり、触媒の反応性が向上する。細孔容積が上限値以下であると、触媒の圧壊強度が高くなる。この細孔容積は、好ましくは０．３〜０．５ｃｍ3／ｇであり、より好ましくは０．３〜０．４ｃｍ3／ｇである。 This carbon monoxide conversion catalyst has a pore volume of 0.3 to 0.6 cm 3 / g. When the pore volume is greater than or equal to the lower limit value, the diffusion rate of carbon monoxide into the catalyst is increased, and the reactivity of the catalyst is improved. When the pore volume is not more than the upper limit value, the crushing strength of the catalyst is increased. This pore volume is preferably 0.3 to 0.5 cm 3 / g, more preferably 0.3 to 0.4 cm 3 / g.
この一酸化炭素変成触媒は、平均細孔半径が４５〜１２０Åである。平均細孔半径がこの範囲内であると、細孔容積が大きくなり、あるいは圧壊強度が高くなる。この平均細孔半径は、好ましくは５０〜１００Åであり、より好ましくは６０〜８０Åである。 This carbon monoxide shift catalyst has an average pore radius of 45 to 120 mm. When the average pore radius is within this range, the pore volume increases or the crushing strength increases. This average pore radius is preferably 50 to 100 mm, more preferably 60 to 80 mm.
本実施の形態に係る一酸化炭素変成触媒は、Ｘ線回折パターンが、格子面間隔ｄ（Å）２．４４±０．０５及び２．８６±０．０５に半値幅１．０度以上のブロードなピークを有することが好ましい。このＸ線回折パターンは、以下のピークを有する亜鉛アルミネートスピネル（ＺｎＡｌ2Ｏ3）のＸ線回折パターンに相当するものである。
ｄ＝２．４４２、ｄ＝２．８６３、ｄ＝１．４３２、ｄ＝１．５５９、ｄ＝１．６５３、ｄ＝１．２８１
ここで半値幅とは、ベースラインからピークの最高点までの高さ（ｈ）の半分の高さ（ｈ／２）におけるピークの幅（すなわち、半値全幅）を意味する。
また、この一酸化炭素変成触媒は、Ｘ線回折パターンが、格子面間隔ｄ（Å）２．４８±０．０５、２．８１±０．０５及び２．６０±０．０５のいずれにもピークを有しないものであることが好ましい。このＸ線回折パターンは、以下のピークを有するジンサイト（ｚｉｎｃｉｔｅ、ＺｎＯ）のＸ線回折パターンに相当するものである。
ｄ＝２．４７５、ｄ＝２．８１４、ｄ＝２．６０２、ｄ＝１．６２５、ｄ＝１．４７７、ｄ＝１．３７８
In the carbon monoxide shift catalyst according to the present embodiment, the X-ray diffraction pattern has a lattice width d (１．０) of 2.44 ± 0.05 and 2.86 ± 0.05, and a half-value width of 1.0 ° or more. It preferably has a broad peak. This X-ray diffraction pattern corresponds to the X-ray diffraction pattern of zinc aluminate spinel (ZnAl 2 O 3 ) having the following peaks.
d = 2.442, d = 2.863, d = 1.432, d = 1.559, d = 1.653, d = 1.281
Here, the half width means a peak width (that is, full width at half maximum) at a height (h / 2) half of the height (h) from the baseline to the highest point of the peak.
In addition, this carbon monoxide conversion catalyst has an X-ray diffraction pattern with a lattice spacing d (Å) of 2.48 ± 0.05, 2.81 ± 0.05, and 2.60 ± 0.05. It is preferable that it does not have a peak. This X-ray diffraction pattern corresponds to an X-ray diffraction pattern of zincite (ZnO) having the following peaks.
d = 2.475, d = 2.814, d = 2.602, d = 1.625, d = 1.477, d = 1.378
すなわち、この一酸化炭素変成触媒は、亜鉛アルミネートスピネルを有すると共に、ジンサイトを実質的に有しない。この亜鉛アルミネートスピネルは、水蒸気存在下でも安定に存在するため、銅のシンタリングが抑制される。また、ジンサイトは水蒸気存在下でジンサイト自体がシンタリングすることにより、銅のシンタリングをも促進するが、この一酸化炭素変成触媒はジンサイトを実質的に有しないため、銅のシンタリングが抑制される。これらにより、この触媒を水性ガスシフト反応用の触媒として燃料電池用改質器に搭載すると、起動・停止を繰り返しても活性の低下が少なく、長期間の使用が可能である。また、この触媒は耐熱性にも優れており、５００℃までの高温においても使用することができるため、水性ガスシフト反応において、低温シフト触媒として使用できるのみならず、高温シフト触媒を兼ねることもできる。また、この一酸化炭素変成触媒は、例えば、水素製造触媒、メタノール合成触媒、メタノールのスチームリフォーミング触媒等として用いることも可能である。
亜鉛アルミネートスピネルの上記Ｘ線回折パターンはブロードなピークを有しており、これは粒径が小さいことを意味する。これにより、亜鉛アルミネートスピネルをＣｕＯの近傍に存在させ、銅のシンタリングを良好に抑制することができる。
That is, this carbon monoxide shift catalyst has zinc aluminate spinel and substantially no ginsite. Since this zinc aluminate spinel exists stably even in the presence of water vapor, copper sintering is suppressed. Zincite also promotes copper sintering by synthesizing itself in the presence of water vapor, but this carbon monoxide shift catalyst has virtually no zinc sites. Is suppressed. Accordingly, when this catalyst is mounted on a fuel cell reformer as a water gas shift reaction catalyst, the activity will not decrease much even if it is repeatedly started and stopped, and it can be used for a long time. Moreover, since this catalyst is excellent also in heat resistance and can be used even at a high temperature up to 500 ° C., it can be used not only as a low temperature shift catalyst but also as a high temperature shift catalyst in the water gas shift reaction. . The carbon monoxide conversion catalyst can also be used, for example, as a hydrogen production catalyst, a methanol synthesis catalyst, a methanol steam reforming catalyst, or the like.
The above X-ray diffraction pattern of zinc aluminate spinel has a broad peak, which means that the particle size is small. Thereby, a zinc aluminate spinel can be made to exist in the vicinity of CuO, and copper sintering can be suppressed favorably.
＜一酸化炭素変成方法＞
本発明の一酸化炭素変成方法では、上記の一酸化炭素変成触媒を用いて１５０〜５００℃、好ましくは１５０〜３００℃において一酸化炭素変成反応（水性ガスシフト反応）により一酸化炭素を含む水素含有ガス中の一酸化炭素濃度を低下させる。
<Carbon monoxide transformation method>
In the carbon monoxide conversion method of the present invention, hydrogen containing carbon monoxide is contained by carbon monoxide conversion reaction (water gas shift reaction) at 150 to 500 ° C., preferably 150 to 300 ° C., using the carbon monoxide conversion catalyst. Reduce the carbon monoxide concentration in the gas.
この一酸化炭素を含む水素含有ガスとしては、炭化水素燃料を脱硫処理後、炭化水素を改質触媒の存在下に部分酸化改質、自己熱改質、水蒸気改質等の改質処理して得られた改質ガス、水性ガス、水添工程における排ガス等が好適に用いられる。炭化水素燃料としては、ＬＰＧ、都市ガス、天然ガス、ナフサ、灯油および軽油のいずれも使用できる。
本発明の一酸化炭素変成方法において、ガス時空間速度（ＧＨＳＶ、ガス体積流量／触媒体積)は、好ましくは２０００〜６００００ｈ-1、より好ましくは３０００〜１００００ｈ-1の条件で行なわれる。
本発明の一酸化炭素変成方法において、前記銅−亜鉛−アルミニウム触媒は使用前に水素還元により還元するのが好ましい。水素還元は、通常、水素（例えば、水素/窒素混合ガス）気流下、１５０〜３００℃程度の温度で、１〜１０時間、好ましくは１〜３時間行う。
As the hydrogen-containing gas containing carbon monoxide, after hydrocarbon fuel is desulfurized, the hydrocarbon is subjected to reforming treatment such as partial oxidation reforming, autothermal reforming, and steam reforming in the presence of a reforming catalyst. The resulting reformed gas, water gas, exhaust gas in the hydrogenation step, and the like are preferably used. As the hydrocarbon fuel, any of LPG, city gas, natural gas, naphtha, kerosene and light oil can be used.
In the carbon monoxide conversion method of the present invention, the gas hourly space velocity (GHSV, gas volume flow rate / catalyst volume) is preferably 2000 to 60000 h −1 , more preferably 3000 to 10000 h −1 .
In the carbon monoxide conversion method of the present invention, the copper-zinc-aluminum catalyst is preferably reduced by hydrogen reduction before use. The hydrogen reduction is usually performed under a hydrogen (for example, hydrogen / nitrogen mixed gas) stream at a temperature of about 150 to 300 ° C. for 1 to 10 hours, preferably 1 to 3 hours.
本発明の一酸化炭素変成方法により、一酸化炭素濃度が１％以下、場合によっては０．２％以下に低減された水素含有ガスを製造することができる。
本発明の前記銅−亜鉛−アルミニウム触媒を使用すると、一酸化炭素濃度が低い（０．６容量％未満）原料ガス及び一酸化炭素濃度が比較的高い（０．６〜２．０容量％）原料ガスのいずれにおいても、一酸化炭素濃度を良好に低減することができ、水性ガスシフト反応器をよりコンパクトにすることができる。
By the carbon monoxide conversion method of the present invention, a hydrogen-containing gas having a carbon monoxide concentration reduced to 1% or less, and in some cases, 0.2% or less can be produced.
When the copper-zinc-aluminum catalyst of the present invention is used, the concentration of carbon monoxide is low (less than 0.6% by volume) and the concentration of carbon monoxide is relatively high (0.6 to 2.0% by volume). In any of the raw material gases, the carbon monoxide concentration can be reduced satisfactorily, and the water gas shift reactor can be made more compact.
＜水素製造方法＞
本発明の水素製造方法では、上記の一酸化炭素変成方法を用いて得られた水素含有ガスの一酸化炭素濃度を、さらに一酸化炭素選択酸化反応又は一酸化炭素選択酸化反応以外の反応により低下させる。
上記の一酸化炭素変成方法を用いて得られた水素含有ガスとして、一酸化炭素を０．２％以下まで低減させた水素含有ガスを用いた場合、この水素含有ガスは、一酸化炭素選択酸化反応以外の反応により一酸化炭素の除去を行うことができる。これにより、一酸化炭素選択酸化反応器を必要とせず、他の種類の反応器を用いることができるため、装置をよりコンパクトにすることができる。なお、一酸化炭素選択酸化反応以外の反応としては、一酸化炭素選択メタン化反応、膜分離等が挙げられるが、一酸化炭素選択メタン化反応を行うことが好ましい。
<Hydrogen production method>
In the hydrogen production method of the present invention, the carbon monoxide concentration of the hydrogen-containing gas obtained using the carbon monoxide conversion method is further reduced by a reaction other than the carbon monoxide selective oxidation reaction or the carbon monoxide selective oxidation reaction. Let
When a hydrogen-containing gas obtained by reducing carbon monoxide to 0.2% or less is used as the hydrogen-containing gas obtained by the carbon monoxide conversion method, the hydrogen-containing gas is selectively oxidized with carbon monoxide. Carbon monoxide can be removed by a reaction other than the reaction. Thereby, since a carbon monoxide selective oxidation reactor is not required and other types of reactors can be used, the apparatus can be made more compact. In addition, examples of the reaction other than the carbon monoxide selective oxidation reaction include a carbon monoxide selective methanation reaction, membrane separation, and the like, but it is preferable to perform a carbon monoxide selective methanation reaction.
以下、実施例を挙げて本発明をさらに詳細に説明するが、本発明はこれらの実施例に限定されるものではない。
なお、各例における諸特性は下記の方法に従って測定した。
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to these Examples.
Various characteristics in each example were measured according to the following methods.
（１）組成
触媒のＣｕ、Ｚｎ、Ａｌ量は、プラズマ発光（ＩＣＰ）法で定量した。Ｃｕ、Ｚｎ、Ａｌの定量値からＣｕＯ、ＺｎＯ、Ａｌ2Ｏ3量を求め、合計を１００質量％になるよう換算した。
（２）比表面積
ユアサアイオニクス社製比表面積測定装置を用い、試料約１００ｍｇを試料管に充填し、前処理として２００℃で２０分間窒素気流中で加熱脱水した。次に液体窒素温度で窒素（３０％）／ヘリウム（７０％）混合ガスを流通させ窒素を吸着させた後、脱離させＴＣＤ（熱伝導度）検出器で測定した窒素の吸着量から比表面積を求めた。
（３）ＸＲＤ測定
ＸＲＤ測定はリガク社製のＸ線回折装置を用いて行なった。所定量の試料をガラス製試料セルに充填し、Ｘ線源としてＣｕ−Ｋα（１．５４０６Å、グラファイトモノクロメーターにより単色化)を使用し、2θ−θ反射法により測定した。ＣｕＯ、ＺｎＡｌ2Ｏ4、ＺｎＯの結晶子径はシェラー式から算出した。
（４）嵩密度
ＪＩＳＫ３３６２に準じて評価した。
（５）細孔容積及び平均細孔半径
ユアサアイオニクス社製全自動ガス吸着量測定装置オートソーブを用い、窒素吸着法により、細孔容積及び平均細孔半径を求めた。
(1) Composition The amount of Cu, Zn, and Al in the catalyst was quantified by a plasma emission (ICP) method. CuO, ZnO, and Al 2 O 3 amounts were determined from the quantitative values of Cu, Zn, and Al, and the total was converted to 100% by mass.
(2) Specific surface area Using a specific surface area measuring device manufactured by Yuasa Ionics Co., Ltd., about 100 mg of a sample was filled in a sample tube, and heat-dehydrated at 200 ° C. for 20 minutes in a nitrogen stream as a pretreatment. Next, nitrogen (30%) / helium (70%) mixed gas was circulated at liquid nitrogen temperature to adsorb nitrogen, and then desorbed and the specific surface area was determined from the amount of nitrogen adsorbed measured with a TCD (thermal conductivity) detector. Asked.
(3) XRD measurement XRD measurement was performed using an X-ray diffractometer manufactured by Rigaku Corporation. A predetermined amount of the sample was filled in a glass sample cell, and Cu-Kα (1.5406 mm, monochromatized with a graphite monochromator) was used as an X-ray source, and measurement was performed by 2θ-θ reflection method. The crystallite diameters of CuO, ZnAl 2 O 4 and ZnO were calculated from the Scherrer equation.
(4) Bulk density It evaluated according to JISK3362.
(5) Pore volume and average pore radius The pore volume and the average pore radius were determined by a nitrogen adsorption method using a fully automatic gas adsorption amount measuring device Autosorb manufactured by Yuasa Ionics.
（６）触媒の活性評価（出口ＣＯ濃度及び転化率）
触媒３ｃｍ3を内径１２ｍｍの反応管に充填した。反応管内で触媒をＨ2/Ｎ2=２０/８０（容量比）の気流中で、２３０℃で２時間、触媒の還元処理を行なった後、ＧＨＳＶ：２,５００ｈ-1の条件でＨ2/ＣＯ/ＣＯ2/Ｈ2Ｏ＝５０/１０/１０/３０（容量％）のガスを導入し、２００℃で１時間ＣＯ転化反応を行った。得られたガスをサンプリングしてガスクロマトグラフィーにてＣＯ濃度を測定した。この結果をもとに、ＣＯ転化率を下記式により求めた。結果を第１表に示す。
ＣＯ転化率（％）＝［（Ａ−Ｂ）／Ａ）］×１００
上記式において、Ａは反応器入口側のＣＯ量［転化前のＣＯ濃度（容量％）×転化前のガス量（ｃｍ3/分）］、Ｂは反応器出口側のＣＯ量［転化後のＣＯ濃度（容量％）×転化後のガス量（ｃｍ3／分）］である。
(6) Evaluation of catalyst activity (outlet CO concentration and conversion)
A reaction tube having an inner diameter of 12 mm was filled with 3 cm 3 of the catalyst. The catalyst was reduced in the reaction tube in an air stream of H 2 / N 2 = 20/80 (volume ratio) at 230 ° C. for 2 hours, and then H 2 under the condition of GHSV: 2,500 h −1. A gas of / CO / CO 2 / H 2 O = 50/10/10/30 (volume%) was introduced, and CO conversion reaction was performed at 200 ° C. for 1 hour. The obtained gas was sampled and the CO concentration was measured by gas chromatography. Based on this result, the CO conversion was determined by the following formula. The results are shown in Table 1.
CO conversion (%) = [(A−B) / A)] × 100
In the above formula, A is the amount of CO on the reactor inlet side [CO concentration before conversion (volume%) × gas amount before conversion (cm 3 / min)], B is the amount of CO on the reactor outlet side [after conversion CO concentration (volume%) × gas amount after conversion (cm 3 / min)].
（７）触媒の耐久性評価
触媒３ｃｍ3を内径１２ｍｍの反応管に充填した。反応管内で触媒をＨ2/Ｎ2=２０/８０（容量比）の気流中で、２３０℃で２時間、触媒の還元処理を行なった後、ＧＨＳＶ：１,４００ｈ-1の条件でＨ2/ＣＯ/ＣＯ2/Ｈ2Ｏ＝５０/１０/１０/３０（容量％）のガスを導入し、１７０℃で１時間ＣＯ転化反応を行った後、水蒸気でパージしながら５０℃まで冷却した。
水蒸気を止めて１時間保持した後、１７０℃、１時間の反応と５０℃での冷却とを繰り返し実施した。この繰り返しによる活性の低下傾向、すなわち繰り返し回数によるＣＯ転化率の低下から、耐久性を評価した。その結果を第２表に示す。
(7) Durability Evaluation of Catalyst 3 cm 3 of catalyst was packed in a reaction tube having an inner diameter of 12 mm. The catalyst was reduced in the reaction tube in a stream of H 2 / N 2 = 20/80 (volume ratio) at 230 ° C. for 2 hours and then H 2 under the condition of GHSV: 1,400 h −1. / CO / CO 2 / H 2 O = 50/10/10/30 (volume%) gas was introduced, CO conversion reaction was performed at 170 ° C. for 1 hour, and then cooled to 50 ° C. while purging with steam. .
After the water vapor was stopped and held for 1 hour, the reaction at 170 ° C. for 1 hour and the cooling at 50 ° C. were repeated. Durability was evaluated from the tendency of the activity to decrease due to repetition, that is, the decrease in CO conversion rate due to the number of repetitions. The results are shown in Table 2.
実施例１
硝酸銅三水和物（純度９９質量％以上）１３３．０ｇ、硝酸亜鉛六水和物（純度９９質量％以上）２１．９ｇ、硝酸アルミニウム九水和物（純度９９質量％以上）６６．２ｇを純水に溶解し、９００ｍｌの水溶液（Ａ液）とした。
また、水酸化ナトリウム２Ｎ溶液をＢ液とした。
Ａ液とＢ液を２００ｍｌの５０℃の水の入った容器に同時に滴下して共沈操作を行った。Ａ液は３０ｍｌ／分の速度で滴下しながら、Ｂ液は沈殿物スラリーのｐＨが約９．８を維持するよう滴下速度を調整した。沈殿物を攪拌しながら５０℃に維持した。この沈殿物を３時間熟成した後のｐＨは９．９であった。熟成後の沈殿物スラリーのｐＨを沈殿ｐＨとして第１表に示す。次いで濾過し、十分水洗を行った。
Example 1
Copper nitrate trihydrate (purity 99% by mass or more) 133.0 g, zinc nitrate hexahydrate (purity 99% by mass or more) 21.9 g, aluminum nitrate nonahydrate (purity 99% by mass or more) 66.2 g Was dissolved in pure water to make 900 ml of an aqueous solution (solution A).
A sodium hydroxide 2N solution was designated as solution B.
Liquid A and liquid B were simultaneously dropped into a container containing 200 ml of water at 50 ° C. to perform a coprecipitation operation. While liquid A was dripped at a rate of 30 ml / min, the dripping speed of liquid B was adjusted so that the pH of the precipitate slurry was maintained at about 9.8. The precipitate was maintained at 50 ° C. with stirring. The pH after aging this precipitate for 3 hours was 9.9. The pH of the precipitate slurry after aging is shown in Table 1 as the precipitation pH. Next, the mixture was filtered and sufficiently washed with water.
沈殿物に、有機化合物添加剤としてメチルセルロース（信越化学工業製メトローズ SM-4000）１．８ｇを添加したのち、１２０℃で一晩乾燥した。
乾燥させた沈殿物に、グラファイトを３質量％加えて、打錠成型機で３φ×３ｍｍの成型体を調製した。
次いで、３５０℃で３時間乾燥し、触媒を得た。
この焼成した触媒の組成、物性、ＣＯ変成活性の評価結果を第１表に示す。また，焼成した触媒のＸＲＤ測定データを図１に、また、還元後の触媒のＸＲＤ測定データを図２に示す。
After adding 1.8 g of methyl cellulose (Shin-Etsu Chemical Co., Ltd., Metrose SM-4000) as an organic compound additive, the precipitate was dried at 120 ° C. overnight.
3% by mass of graphite was added to the dried precipitate, and a 3φ × 3 mm molded body was prepared with a tableting molding machine.
Subsequently, it dried at 350 degreeC for 3 hours, and the catalyst was obtained.
Table 1 shows the evaluation results of the composition, physical properties, and CO conversion activity of the calcined catalyst. FIG. 1 shows XRD measurement data of the calcined catalyst, and FIG. 2 shows XRD measurement data of the catalyst after reduction.
焼成した触媒では、ＣｕＯとＺｎＡｌ2Ｏ4のピークが重なっており明らかではないが、図２よりＣｕＯを還元するとＺｎＡｌ2Ｏ4ピークが存在することと、ＺｎＯピークが存在しないことがわかる。
第２表に耐久性の評価結果を示す。反応（１７０℃、１ｈ）と冷却（５０℃）を１００回繰り返した後のＣＯ転化率の低下は、わずか１．０％であり、本触媒は耐久性が高いことが明らかになった。
In the calcined catalyst, the peaks of CuO and ZnAl 2 O 4 overlap each other, which is not clear, but FIG. 2 shows that when CuO is reduced, a ZnAl 2 O 4 peak is present and no ZnO peak is present.
Table 2 shows the durability evaluation results. The decrease in CO conversion after repeating the reaction (170 ° C., 1 h) and cooling (50 ° C.) 100 times was only 1.0%, and it was revealed that this catalyst has high durability.
実施例２
有機化合物添加剤としてのメチルセルロースの添加量を、１．８ｇに代えて０．６ｇとしたこと以外は実施例１と同様に調製及び測定した。
触媒のＸＲＤ測定結果は実施例１と同様であった。
Example 2
Preparation and measurement were performed in the same manner as in Example 1 except that the amount of methylcellulose added as an organic compound additive was 0.6 g instead of 1.8 g.
The XRD measurement result of the catalyst was the same as in Example 1.
実施例３
有機化合物添加剤としてのメチルセルロースの添加量を、１．８ｇに代えて３．０ｇとしたこと以外は実施例１と同様に調製及び測定した。
触媒のＸＲＤ測定結果は実施例１と同様であった。
Example 3
It was prepared and measured in the same manner as in Example 1 except that the amount of methylcellulose added as an organic compound additive was changed to 3.0 g instead of 1.8 g.
The XRD measurement result of the catalyst was the same as in Example 1.
実施例４
硝酸銅三水和物９４．４ｇ、硝酸亜鉛六水和物３７．７ｇ、硝酸アルミニウム九水和物１１０．０ｇとしたこと以外は実施例１と同様に調製及び測定した。
触媒のＸＲＤは実施例１と同様であった。
Example 4
Preparation and measurement were performed in the same manner as in Example 1 except that 94.4 g of copper nitrate trihydrate, 37.7 g of zinc nitrate hexahydrate, and 110.0 g of aluminum nitrate nonahydrate were used.
The XRD of the catalyst was the same as in Example 1.
実施例５
硝酸銅三水和物１３３．０ｇ、硝酸亜鉛六水和物１８．３ｇ、硝酸アルミニウム九水和物７３．６ｇとしたこと以外は実施例１と同様に調製及び測定した。
触媒のＸＲＤは実施例１と同様であった。
Example 5
Preparation and measurement were performed in the same manner as in Example 1 except that 133.0 g of copper nitrate trihydrate, 18.3 g of zinc nitrate hexahydrate, and 73.6 g of aluminum nitrate nonahydrate were used.
The XRD of the catalyst was the same as in Example 1.
実施例６
有機化合物添加剤としてのメチルセルロースの添加量を、１．８ｇに代えて０．５ｇとしたこと以外は実施例１と同様に調製及び測定した。
触媒のＸＲＤ測定結果は実施例１と同様であった。
Example 6
Preparation and measurement were performed in the same manner as in Example 1 except that the amount of methylcellulose added as an organic compound additive was changed to 0.5 g instead of 1.8 g.
The XRD measurement result of the catalyst was the same as in Example 1.
実施例７
有機化合物添加剤としてのメチルセルロースに代えてポリビニルアルコールを０．５ｇ添加したこと以外は実施例１と同様に調製及び測定した。
触媒のＸＲＤ測定結果は実施例１と同様であった。
Example 7
It prepared and measured in the same manner as in Example 1 except that 0.5 g of polyvinyl alcohol was added instead of methyl cellulose as an organic compound additive.
The XRD measurement result of the catalyst was the same as in Example 1.
実施例８
有機化合物添加剤としてのメチルセルロースに代えてエタノールを３．０ｇ添加したこと以外は実施例１と同様に調製及び測定した。
触媒のＸＲＤ測定結果は実施例１と同様であった。
Example 8
Preparation and measurement were performed in the same manner as in Example 1 except that 3.0 g of ethanol was added instead of methyl cellulose as an organic compound additive.
The XRD measurement result of the catalyst was the same as in Example 1.
実施例９
実施例１で得た沈殿物を洗浄後、メチルセルロース１．８ｇを添加し、混合及び風乾した。
風乾後の沈殿物を原料として押出成型機で２φ×５ｍｍの成型体を調製した。
次いで、１２０℃で一晩乾燥後、３５０℃で３時間焼成し、触媒を得た。
触媒のＸＲＤ測定結果は実施例１と同様であった。
Example 9
After washing the precipitate obtained in Example 1, 1.8 g of methylcellulose was added, mixed and air-dried.
Using a precipitate after air drying as a raw material, a 2φ × 5 mm molded body was prepared by an extrusion molding machine.
Subsequently, after drying at 120 degreeC overnight, it baked at 350 degreeC for 3 hours, and obtained the catalyst.
The XRD measurement result of the catalyst was the same as in Example 1.
比較例１
硝酸銅三水和物１３３．０ｇ、硝酸亜鉛六水和物２１．９ｇ、硝酸アルミニウム九水和物６６．２ｇを用いて、実施例１と同様に共沈操作を行った。
水洗し、１２０℃で一晩乾燥後、３５０℃で３時間焼成を行った。
得られた焼成品にグラファイトを３質量％加えて打錠成型し、３φ×３ｍｍの成型体を調製した。
触媒のＸＲＤは実施例１と同様であった。
第１表に示すとおり、比較例１の触媒は、実施例の触媒よりもＣｕＯ結晶子径が大きく、細孔容積、細孔径が小さかった。また、比較例１の触媒の活性は実施例の触媒と同等だが、第２表のとおり耐久処理後は活性が４．１％低下し、実施例１より耐久性に劣っていた。
Comparative Example 1
A coprecipitation operation was performed in the same manner as in Example 1 using 133.0 g of copper nitrate trihydrate, 21.9 g of zinc nitrate hexahydrate, and 66.2 g of aluminum nitrate nonahydrate.
It was washed with water, dried at 120 ° C. overnight, and then fired at 350 ° C. for 3 hours.
3% by mass of graphite was added to the obtained fired product and subjected to tableting molding to prepare a molded body of 3φ × 3 mm.
The XRD of the catalyst was the same as in Example 1.
As shown in Table 1, the catalyst of Comparative Example 1 had a larger CuO crystallite diameter, smaller pore volume, and smaller pore diameter than the catalyst of the Example. Further, the activity of the catalyst of Comparative Example 1 was equivalent to that of the catalyst of the Example, but as shown in Table 2, the activity decreased by 4.1% after the durability treatment, and the durability was inferior to that of Example 1.
本発明の一酸化炭素変成触媒は、活性及び耐久性ともに優れているため、コンパクトなシステムが可能となり、家庭用燃料電池や燃料電池車に搭載するコンパクトな改質システムが可能である。本発明の一酸化炭素変成触媒は、水性ガスシフト反応の低温シフト触媒の他、水性ガスシフト反応の高温シフト触媒、水素製造触媒、メタノール合成触媒、メタノールのスチームリフォーミング触媒等として利用することも可能である。 Since the carbon monoxide conversion catalyst of the present invention is excellent in both activity and durability, a compact system is possible, and a compact reforming system mounted on a domestic fuel cell or a fuel cell vehicle is possible. The carbon monoxide conversion catalyst of the present invention can be used as a low temperature shift catalyst for water gas shift reaction, a high temperature shift catalyst for water gas shift reaction, a hydrogen production catalyst, a methanol synthesis catalyst, a methanol steam reforming catalyst, and the like. is there.
Claims (14)
前記銅、亜鉛、及びアルミニウムを、それぞれ、ＣｕＯ、ＺｎＯ、及びＡｌ2Ｏ3に換算したときに、ＣｕＯが３０〜９０質量％、ＺｎＯが３〜３０質量％、及びＡｌ2Ｏ3が７〜６０質量％であり、
比表面積が８０〜２００ｍ2／ｇ、ＣｕＯ結晶子径が１２０Å以下、嵩密度が０．６〜１．５ｇ／ｃｍ3、細孔容積が０．３〜０．６ｃｍ3／ｇ、及び平均細孔半径が４５〜１２０Åであることを特徴とする一酸化炭素変成触媒。 A carbon monoxide conversion catalyst comprising a copper-zinc-aluminum catalyst containing copper, zinc, aluminum and oxygen,
When the copper, zinc, and aluminum are converted into CuO, ZnO, and Al 2 O 3 , respectively, CuO is 30 to 90% by mass, ZnO is 3 to 30% by mass, and Al 2 O 3 is 7 to 7%. 60% by mass,
Specific surface area of 80 to 200 m 2 / g, CuO crystallite diameter of 120 mm or less, bulk density of 0.6 to 1.5 g / cm 3 , pore volume of 0.3 to 0.6 cm 3 / g, and average fineness A carbon monoxide shift catalyst having a pore radius of 45 to 120 mm.
格子面間隔ｄ（Å） ２．４８±０．０５、２．８１±０．０５、２．６０±０．０５のいずれにもピークが存在しない請求項１に記載の一酸化炭素変成触媒。 In the X-ray diffraction pattern, it has a broad peak with a half-value width of 1.0 degree or more at the lattice spacing d (Å) 2.44 ± 0.05 and 2.86 ± 0.05,
The carbon monoxide conversion catalyst according to claim 1, wherein no peak exists in any of lattice spacing d (間隔) 2.48 ± 0.05, 2.81 ± 0.05, 2.60 ± 0.05.
前記成型工程よりも前に前記沈殿物に有機化合物添加剤を含有させる添加工程を有することを特徴とする請求項１又は２に記載の一酸化炭素変成触媒の製造方法。 A coprecipitation step of coprecipitation of a metal salt solution containing copper, zinc and aluminum and a precipitant-containing aqueous solution containing a precipitant to obtain a catalyst precursor, a washing step of the catalyst precursor, and the catalyst precursor A drying step, a molding step of molding the catalyst precursor into a molded body, and a firing step of firing the molded body into a carbon monoxide conversion catalyst,
The method for producing a carbon monoxide conversion catalyst according to claim 1 or 2, further comprising an addition step of adding an organic compound additive to the precipitate before the molding step.
Ｃｕ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．３〜０．９、
Ｚｎ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．０５〜０．３、
Ａｌ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．０７〜０．６、
Ａｌ／Ｚｎ=２〜１０
である請求項４に記載の一酸化炭素変成触媒の製造方法。 In the coprecipitation step, the atomic ratio of the metal component in the metal salt solution is
Cu / (Cu + Zn + Al) = 0.3 to 0.9,
Zn / (Cu + Zn + Al) = 0.05-0.3,
Al / (Cu + Zn + Al) = 0.07-0.6,
Al / Zn = 2-10
The method for producing a carbon monoxide conversion catalyst according to claim 4.
Ｃｕ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．３〜０．９、
Ｚｎ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．０５〜０．３、
Ａｌ／（Ｃｕ+Ｚｎ+Ａｌ）＝０．０７〜０．６、
Ａｌ／Ｚｎ=２〜１０
であり、
前記沈殿剤含有水溶液が、ＣＯ3を有する塩基性物質を含むものであり、
前記金属塩溶液と前記沈殿剤含有水溶液とを、ｐＨ５〜７、温度６５℃以下で共沈させて触媒前駆体を得る請求項３に記載の一酸化炭素変成触媒の製造方法。 In the coprecipitation step, the atomic ratio of the metal component in the metal salt solution is
Cu / (Cu + Zn + Al) = 0.3 to 0.9,
Zn / (Cu + Zn + Al) = 0.05-0.3,
Al / (Cu + Zn + Al) = 0.07-0.6,
Al / Zn = 2-10
And
The precipitant-containing aqueous solution contains a basic substance having CO 3 ;
The method for producing a carbon monoxide conversion catalyst according to claim 3, wherein the catalyst precursor is obtained by coprecipitation of the metal salt solution and the precipitant-containing aqueous solution at a pH of 5 to 7 and a temperature of 65 ° C or lower.
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