JP6929757B2 - Method for manufacturing highly active platinum catalyst - Google Patents
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- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 title claims description 160
- 239000003054 catalyst Substances 0.000 title claims description 78
- 229910052697 platinum Inorganic materials 0.000 title claims description 78
- 238000004519 manufacturing process Methods 0.000 title claims description 17
- 238000000034 method Methods 0.000 title description 46
- 238000011282 treatment Methods 0.000 claims description 52
- UYXRCZUOJAYSQR-UHFFFAOYSA-N nitric acid;platinum Chemical compound [Pt].O[N+]([O-])=O UYXRCZUOJAYSQR-UHFFFAOYSA-N 0.000 claims description 38
- 239000007864 aqueous solution Substances 0.000 claims description 32
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 30
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 23
- 239000007789 gas Substances 0.000 claims description 20
- 239000012018 catalyst precursor Substances 0.000 claims description 17
- 239000001257 hydrogen Substances 0.000 claims description 17
- 229910052739 hydrogen Inorganic materials 0.000 claims description 17
- 239000002245 particle Substances 0.000 claims description 11
- 239000011148 porous material Substances 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 description 13
- 239000002253 acid Substances 0.000 description 12
- 229910000510 noble metal Inorganic materials 0.000 description 12
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
- 230000032683 aging Effects 0.000 description 10
- 238000012423 maintenance Methods 0.000 description 10
- 239000002638 heterogeneous catalyst Substances 0.000 description 9
- 239000000243 solution Substances 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 238000002835 absorbance Methods 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 229910001873 dinitrogen Inorganic materials 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000010304 firing Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000006555 catalytic reaction Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 238000005470 impregnation Methods 0.000 description 6
- 239000000376 reactant Substances 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 239000003426 co-catalyst Substances 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 239000010970 precious metal Substances 0.000 description 3
- 229910052723 transition metal Inorganic materials 0.000 description 3
- 150000003624 transition metals Chemical class 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 238000011481 absorbance measurement Methods 0.000 description 2
- 229910052797 bismuth Inorganic materials 0.000 description 2
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
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- 229910052802 copper Inorganic materials 0.000 description 2
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 239000002815 homogeneous catalyst Substances 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 238000005984 hydrogenation reaction Methods 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
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- 229910052720 vanadium Inorganic materials 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- 239000007848 Bronsted acid Substances 0.000 description 1
- 239000002841 Lewis acid Substances 0.000 description 1
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- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
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- 150000003057 platinum Chemical class 0.000 description 1
- NWAHZABTSDUXMJ-UHFFFAOYSA-N platinum(2+);dinitrate Chemical compound [Pt+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O NWAHZABTSDUXMJ-UHFFFAOYSA-N 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
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- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
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Description
本発明は、γ−アルミナ担体に、活性種である白金のＭＳＡ（Metal Surface Area）値が大きい、高活性白金触媒の製造方法に関する。 The present invention relates to a method for producing a highly active platinum catalyst in which a γ-alumina carrier has a large MSA (Metal Surface Area) value of platinum, which is an active species.
有機合成化学の分野において、その合成反応に触媒が使用されることは周知のとおりである。このような触媒には均一系と言われる触媒と、不均一系と言われる触媒があることが知られている。均一系触媒は、触媒としての機能を有する酸、塩基、金属錯体等を利用するものが知られており、反応物、生成物、並びに一般的には液体の触媒を均一層として混合して使用される。これに対して不均一系触媒は、活性炭や多孔質のシリカやアルミナ等無機酸化物を担体とし、反応物と接触する担体の表面側に白金やパラジウム等の触媒活性種が担持されて使用される。 It is well known that catalysts are used in the synthetic reaction in the field of synthetic organic chemistry. It is known that such catalysts include a catalyst called a homogeneous system and a catalyst called a non-homogeneous system. Homogeneous catalysts are known to utilize acids, bases, metal complexes, etc. that function as catalysts, and reactants, products, and generally liquid catalysts are mixed and used as a homogeneous layer. Will be done. On the other hand, the heterogeneous catalyst is used by using activated carbon or an inorganic oxide such as porous silica or alumina as a carrier and supporting a catalytically active species such as platinum or palladium on the surface side of the carrier in contact with the reactant. NS.
均一系触媒反応は、反応物と触媒を分子レベルで混合して使用されることから、選択性が高く、比較的温和な条件で反応が促進する。しかし、反応に使用した触媒の変質、反応系からの触媒の回収、生成物からの触媒の分離が困難であることから、特に触媒として高価な貴金属を使用した場合には、回収や再利用の点で不均一系触媒と比べると産業的に不利な触媒であるともいえる。 Since the homogeneous catalytic reaction is used by mixing the reactant and the catalyst at the molecular level, the reaction is promoted under relatively mild conditions with high selectivity. However, since it is difficult to alter the catalyst used in the reaction, recover the catalyst from the reaction system, and separate the catalyst from the product, recovery and reuse are possible, especially when an expensive noble metal is used as the catalyst. In that respect, it can be said that the catalyst is industrially disadvantageous as compared with the non-homogeneous catalyst.
これに対して不均一系触媒は、気相反応であれば固定床中に触媒を配置するか、液相反応であれば流動床反応装置中に触媒を混合し、所定の条件の下、反応物を流通させることで触媒反応を促進して生成物を得ることができる。特に触媒を固定床として使用した場合には、反応系に対して反応物を連続的に供給することが可能であり、化学工業において生成物を大量に生産するのに適した触媒であるといえる。 On the other hand, in the case of a heterogeneous catalyst, the catalyst is placed in a fixed bed in the case of a gas phase reaction, or the catalyst is mixed in a fluidized bed reactor in the case of a liquid phase reaction, and the reaction is carried out under predetermined conditions. By circulating the product, the catalytic reaction can be promoted to obtain the product. In particular, when the catalyst is used as a fixed bed, the reactants can be continuously supplied to the reaction system, and it can be said that the catalyst is suitable for mass production of products in the chemical industry. ..
不均一系触媒は担体に貴金属等の活性種を担持した触媒であり、酸点を有する担体を使用することで優れた活性を発揮することが知られており、このような担体としてはγ−アルミナが知られている。担体の酸点は酸化物中のルイス酸点、ブレンステッド酸点に由来し、担体においてはその表面に固定された位置にある。不均一系触媒反応においては、反応物は酸点に吸着することで促進する（非特許文献１）。このような酸点は同じ材質からなる担体であれば比表面積値（ＢＥＴ値）が大きいほど相対的に担体表面の酸点は多くなる。不均一系触媒はこのように貴金属等の活性種と担体の酸点利用した反応であることから二元機能型触媒と言われることがある（特許文献１）。 The heterogeneous catalyst is a catalyst in which an active species such as a noble metal is supported on a carrier, and it is known that excellent activity is exhibited by using a carrier having an acid point. As such a carrier, γ- Alumina is known. The acid point of the carrier is derived from the Lewis acid point and the Bronsted acid point in the oxide, and is fixed to the surface of the carrier. In the heterogeneous catalytic reaction, the reactant is promoted by adsorbing to the acid point (Non-Patent Document 1). As for such acid points, if the carrier is made of the same material, the larger the specific surface area value (BET value), the larger the acid points on the surface of the carrier. The heterogeneous catalyst is sometimes referred to as a dual-function catalyst because it is a reaction using an active species such as a noble metal and an acid point of a carrier (Patent Document 1).
このような酸点は不均一系触媒を使用した反応においては時としてネガティブな作用を発現することがある。酸点が多量に有る場合、触媒表面における過剰な反応が懸念され、過剰な反応が促進すると副反応物を生成してしまうことがある。このような過剰な反応は、選択率という点からみると目的生成物の収率の低下要因になることがある（特許文献２）。そのため、担体ＢＥＴ値の大き過ぎる担体は産業用途の触媒として不利な場合がある。 Such acid points sometimes exhibit a negative effect in a reaction using a heterogeneous catalyst. If there are a large number of acid points, there is a concern about an excessive reaction on the catalyst surface, and if the excessive reaction is promoted, a side reaction product may be produced. Such an excessive reaction may cause a decrease in the yield of the target product in terms of selectivity (Patent Document 2). Therefore, a carrier having an excessively large carrier BET value may be disadvantageous as a catalyst for industrial use.
また、ＢＥＴ値が高過ぎる担体は触媒の使用条件が高温であったり還元雰囲気であったりした場合、シンタリングをおこして触媒としての性能を低下し易いことは、当業者に取っては周知であり、触媒設計においては不用意にＢＥＴ値の高い担体を選択すべきものではないものとされている。 Further, it is well known to those skilled in the art that a carrier having an excessively high BET value tends to cause sintering and deteriorate the performance as a catalyst when the catalyst is used under high temperature or in a reducing atmosphere. Therefore, it is said that a carrier having a high BET value should not be carelessly selected in the catalyst design.
このような触媒に担持される活性種には、広く触媒活性が期待される白金が用いられ、それに更に金、銅、鉄、ビスマス、バナジウム、クロム等の遷移金属を助触媒として担持させることができ工業的にも普及している。 Platinum, which is expected to have wide catalytic activity, is used as the active species supported on such a catalyst, and transition metals such as gold, copper, iron, bismuth, vanadium, and chromium can be supported as an auxiliary catalyst. It is also industrially popular.
このように白金は触媒における有効な活性種であるが、他方で高価な金属としても知られている。白金を産業用途の触媒として使用する場合、そのコスト低減は重要な課題である。触媒コストの低減にあたっては、使用する白金の量を少なくすることが最も効果的な手段の一つであるが、単に活性種である白金の使用量を減らしたのでは触媒の活性としては低下してしまう。 Thus, platinum is an effective active species in catalysts, but on the other hand it is also known as an expensive metal. When platinum is used as a catalyst for industrial applications, its cost reduction is an important issue. One of the most effective means for reducing the catalyst cost is to reduce the amount of platinum used, but simply reducing the amount of platinum, which is an active species, reduces the activity of the catalyst. It ends up.
このような事情から、不均一系触媒ではこのような高価な白金を少ない使用量で効果的に用いるために、担体上の白金はできるだけ高分散な状態であることが好ましい。白金が高分散な状態とは、担体上の貴金属の粒子サイズが小さいことであり、粒子サイズが小さいことで貴金属の単位重量あたりの表面積は大きくなり活性面は広くなる。このような貴金属の単位重量あたりの表面積についてはＭＳＡ（Metal Surface Area）として［ｍ２／ｇ］で表されることがあり、不均一系触媒においてはＭＳＡ値が大きい触媒は活性に優れた触媒であると言える。 Under these circumstances, in order to effectively use such expensive platinum in a small amount in a heterogeneous catalyst, it is preferable that the platinum on the carrier is in a highly dispersed state as much as possible. The state in which platinum is highly dispersed means that the particle size of the noble metal on the carrier is small, and the small particle size increases the surface area per unit weight of the noble metal and widens the active surface. The surface area per unit weight of such a noble metal may be expressed as [m 2 / g] as MSA (Metal Surface Area), and in a heterogeneous catalyst, a catalyst having a large MSA value is a catalyst having excellent activity. It can be said that.
不均一系触媒においてこのようにＭＳＡ値が大きな触媒を得るためには担体のＢＥＴ値が大きな担体が使用される。ＢＥＴ値が大きいことは担体の表面積が広いことを表し、担持された貴金属粒子同士が凝集し難い距離を保って分散することが可能になる。しかし、ＢＥＴ値が大きな担体は前述した様に必然的に酸点が多い担体となることから、酸点が多い担体において懸念される過剰な活性が懸念される。担体が低ＢＥＴ値であればこのような酸点に由来する副生物生成の懸念や、シンタリングの影響による耐久性の懸念は低減するが、活性種は分散性が低下し、ＭＳＡ値が大きい状態になり難くなる。 In a heterogeneous catalyst, a carrier having a large BET value is used in order to obtain a catalyst having such a large MSA value. A large BET value indicates that the surface area of the carrier is large, and the supported noble metal particles can be dispersed while maintaining a distance at which they are difficult to aggregate. However, since a carrier having a large BET value inevitably becomes a carrier having a large number of acid points as described above, there is a concern about excessive activity which is a concern in a carrier having a large number of acid points. If the carrier has a low BET value, the concern about the formation of by-products derived from such acid points and the concern about durability due to the influence of sintering are reduced, but the dispersibility of the active species is reduced and the MSA value is large. It becomes difficult to be in a state.
このように、白金を担持した不均一系触媒においては、できるだけ少ない貴金属の使用量でＭＳＡ値を大きくすることが可能な触媒技術の実現が望まれていた。 As described above, in the heterogeneous catalyst supporting platinum, it has been desired to realize a catalyst technology capable of increasing the MSA value with the least amount of precious metal used.
本発明者は、上記課題を解決するために鋭意研究した結果、γ−アルミナに白金成分を担持させた触媒前駆体を、水素含有ガスを使用して加熱還元処理をするにあたり、特定の温度範囲から加熱還元処理を開始することにより、上記課題を解決する、ＭＳＡ値が大きく高活性な白金触媒が製造できることを見出し、本発明を完成させた。 As a result of diligent research to solve the above problems, the present inventor has applied a catalyst precursor in which a platinum component is supported on γ-alumina to a heat reduction treatment using a hydrogen-containing gas in a specific temperature range. The present invention has been completed by finding that a platinum catalyst having a large MSA value and high activity can be produced by starting the heat reduction treatment from the above.
すなわち、本発明は、γ−アルミナ担体に、ジニトロジアミン白金硝酸水溶液を含浸させた後、白金成分を焼成固定して触媒前駆体を調製し、次いで、これに水素含有ガスを使用して加熱還元処理を施す白金触媒の製造方法であって、
加熱還元処理を開始する温度が３００〜６００℃であることを特徴とする高活性白金触媒の製造方法である。
That is, in the present invention, a γ-alumina carrier is impregnated with an aqueous solution of dinitrodiamine platinum nitric acid, and then the platinum component is calcined and fixed to prepare a catalyst precursor, which is then heat-reduced using a hydrogen-containing gas. A method for producing a platinum catalyst to be treated.
It is a method for producing a highly active platinum catalyst, characterized in that the temperature at which the heat reduction treatment is started is 300 to 600 ° C.
本発明の製造方法によれば、担体としてγ−アルミナを使用した場合であっても白金のＭＳＡ値を大きなものとすることが可能であり、これによりできるだけ少ない貴金属の使用量でＭＳＡ値が大きく高活性な触媒を得ることができる。 According to the production method of the present invention, it is possible to increase the MSA value of platinum even when γ-alumina is used as the carrier, whereby the MSA value can be increased with the minimum amount of precious metal used. A highly active catalyst can be obtained.
本発明の高活性白金触媒の製造方法（以下、「本発明方法」という）は、γ−アルミナ担体に、ジニトロジアミン白金硝酸水溶液を含浸させた後、白金成分を焼成固定して触媒前駆体を調製し、次いで、これに水素含有ガスを使用して加熱還元処理を施す白金触媒の製造方法であって、
加熱還元処理を開始する温度が３００〜６００℃の方法である。
In the method for producing a highly active platinum catalyst of the present invention (hereinafter referred to as "the method of the present invention"), a γ-alumina carrier is impregnated with a dinitrodiamine platinum nitric acid aqueous solution, and then the platinum component is calcined and fixed to prepare a catalyst precursor. A method for producing a platinum catalyst, which is prepared and then subjected to a heat reduction treatment using a hydrogen-containing gas.
This is a method in which the temperature at which the heat reduction treatment is started is 300 to 600 ° C.
（γ−アルミナ担体）
本発明方法に使用されるγ−アルミナ担体の性状は特に限定されないが、例えば、ＢＥＴ値は５０〜３００［ｍ２／ｇ］であることが好ましく、１００〜２００［ｍ２／ｇ］であることがより好ましい。ＢＥＴ値が小さすぎるとそもそも白金を高分散な状態、すなわちＭＳＡ値が大きな状態で担持させることが難しく、大きすぎると触媒製造時の加熱や触媒使用時の熱履歴や雰囲気の影響で担体が焼結を起すことがあり、この場合も貴金属ＭＳＡ値は小さくなってしまう。
(Γ-Alumina carrier)
The properties of the γ-alumina carrier used in the method of the present invention are not particularly limited, but for example, the BET value is preferably 50 to 300 [m 2 / g], preferably 100 to 200 [m 2 / g]. Is more preferable. If the BET value is too small, it is difficult to support platinum in a highly dispersed state, that is, in a state where the MSA value is large. It may cause a bond, and in this case as well, the precious metal MSA value becomes small.
また、上記γ−アルミナ担体は紛体であってもよいが成型担体であることが好ましい。成型担体であれば触媒を固定床として利用でき、所定の条件の下で反応物を流通させることで生成物が得られ、生成物からの触媒の分離も必要無く、産業上有利な触媒であると言える。 The γ-alumina carrier may be a powder, but is preferably a molded carrier. If it is a molded carrier, the catalyst can be used as a fixed bed, a product can be obtained by circulating the reaction product under predetermined conditions, and there is no need to separate the catalyst from the product, which is an industrially advantageous catalyst. It can be said that.
このような成型担体の形状については特に限定されるものでは無く、球状、ペレット状、ハニカム状等広く産業用途に使用される形状の担体を選ぶことができるが球状担体であることが好ましい。球状であれば担体への貴金属塩溶液の含浸深さも一様に制御することが容易であり、白金塩含浸後の還元においても熱の伝わり方、還元成分と貴金属塩の接触も一様であり、最終的に担体上に担持された白金粒子の状態も一様なものになり易い。このような球状担体を使用する場合、その粒子径は特に限定されるものでは無く、産業触媒の用途として広く使用される直径１〜８ｍｍの球状担体を使用できる。 The shape of such a molded carrier is not particularly limited, and a carrier having a shape widely used for industrial purposes such as spherical, pellet-shaped, and honeycomb-shaped can be selected, but a spherical carrier is preferable. If it is spherical, it is easy to uniformly control the impregnation depth of the noble metal salt solution on the carrier, and even in the reduction after impregnation with the platinum salt, the heat transfer method and the contact between the reducing component and the noble metal salt are uniform. Finally, the state of the platinum particles supported on the carrier tends to be uniform. When such a spherical carrier is used, its particle size is not particularly limited, and a spherical carrier having a diameter of 1 to 8 mm, which is widely used for industrial catalyst applications, can be used.
上記成型担体の中でも、内部に空隙を有するものが好ましい。このような成型担体が触媒化されることで空隙を形成する担体の表面に白金が担持される。一方、反応する基質はこの触媒化された担体の空隙に入り込み反応して反応物を生成する。このような空隙は細孔容積として表される。本発明方法にこのような成型担体を使用する場合、その空隙の量は０．４〜０．７［ｍＬ／ｇ］であることが好ましい。 Among the above-mentioned molded carriers, those having voids inside are preferable. Platinum is supported on the surface of the carrier that forms voids by catalyzing such a molded carrier. On the other hand, the reacting substrate enters the voids of this catalyzed carrier and reacts to produce a reactant. Such voids are represented as pore volume. When such a molded carrier is used in the method of the present invention, the amount of the voids is preferably 0.4 to 0.7 [mL / g].
なお、上記γ−アルミナ担体には、得られる触媒の作用を損なわない限り、γ相以外のアルミナや、チタニア、シリカ等、一般的に触媒の担体として使用し得る他の成分を含有していてもよい。 The γ-alumina carrier contains alumina other than the γ phase, titania, silica, and other components that can be generally used as a catalyst carrier as long as the action of the obtained catalyst is not impaired. May be good.
（ジニトロジアミン白金硝酸水溶液）
本発明方法に使用されるジニトロジアミン白金硝酸水溶液は、ジニトロジアミン白金を硝酸で水溶液化したものである。このジニトロジアミン白金硝酸水溶液における、ジニトロジアミン白金の濃度は、γ−アルミナ担体に担持させようとする白金量に応じて適宜その濃度を調整すればよい。
(Dinitrodiamine platinum nitric acid aqueous solution)
The dinitrodiamine platinum nitric acid aqueous solution used in the method of the present invention is an aqueous solution of dinitrodiamine platinum with nitric acid. The concentration of dinitrodiamine platinum in this dinitrodiamine platinum nitric acid aqueous solution may be appropriately adjusted according to the amount of platinum to be supported on the γ-alumina carrier.
ジニトロジアミン白金硝酸水溶液は、当初はやや黄色身がかった透明であり、この時の上記条件における吸光度は極めて低い（概ね０．０５以下） 。このようなジニトロジアミン白金硝酸水溶液は加熱やエージングを施すことで熟成することができる。熟成されたジニトロジアミン白金硝酸水溶液は吸光度が高くなる。ジニトロジアミン白金硝酸水溶液の熟成についてはかねてから知られている（例えば、特開２００５−３０６７００号公報、特開昭５５−８８８４８号公報等）。本発明方法に使用される吸光度のジニトロジアミン白金硝酸水溶液を得る手段についてはこのような公知の手法を採用でき、熟成の手法については特に限定されるものではない。熟成は、例えば、ジニトロジアミン白金硝酸水溶液を加熱保持や所定の時間保持することによっても得られる。本発明方法においては、このように熟成を施したジニトロジアミン白金硝酸水溶液を使用してもよく、熟成を施さずに使用してもよいが、熟成を施したジニトロジアミン白金硝酸水溶液を使用することによりＭＳＡ値が熟成を施さない場合よりも大きくなることから好ましい。 The dinitrodiamine platinum nitric acid aqueous solution was initially slightly yellowish and transparent, and the absorbance under the above conditions at this time was extremely low (approximately 0.05 or less). Such a dinitrodiamine platinum nitric acid aqueous solution can be aged by heating or aging. The aged dinitrodiamine platinum nitric acid aqueous solution has a high absorbance. The aging of dinitrodiamine platinum nitric acid aqueous solution has been known for a long time (for example, JP-A-2005-306700, JP-A-55-88848, etc.). Such a known method can be adopted as a means for obtaining an aqueous solution of dinitrodiamine platinum nitric acid having an absorbance used in the method of the present invention, and the aging method is not particularly limited. Aging can also be obtained, for example, by heating and holding the dinitrodiamine platinum nitric acid aqueous solution or holding it for a predetermined time. In the method of the present invention, the dinitrodiamine platinum nitric acid aqueous solution aged in this way may be used or may be used without aging, but the aged dinitrodiamine platinum nitric acid aqueous solution should be used. This is preferable because the MSA value becomes larger than that in the case where no aging is performed.
ジニトロジアミン白金硝酸水溶液を熟成する場合、２０℃の液温では数年の熟成期間が必要であるが、金属白金換算のジニトロジアミン白金と硝酸が共に１５ｗｔ％以上となる濃度であれば、６０〜１２０℃で１〜２４時間程度の加熱により熟成させることができる。本発明者らの知見によれば、ジニトロジアミン白金硝酸水溶液の濃度が高い方が、また、熟成温度は高い方が、熟成時間は短くなることが分かっている。 When aging a dinitrodiamine platinum nitric acid aqueous solution, a aging period of several years is required at a liquid temperature of 20 ° C. However, if the concentration of both dinitrodiamine platinum and nitric acid in terms of metallic platinum is 15 wt% or more, 60 to 60 to It can be aged by heating at 120 ° C. for about 1 to 24 hours. According to the findings of the present inventors, it is known that the higher the concentration of the dinitrodiamine platinum nitric acid aqueous solution and the higher the aging temperature, the shorter the aging time.
なお、ジニトロジアミン白金硝酸水溶液は、希釈してもよい。希釈の程度は特に限定されないが、例えば、金属白金換算の濃度として０．００５〜５ｗｔ％が好ましく、０．００５〜２ｗｔ％がより好ましい。白金濃度が低すぎる場合は担持される白金品位も低くなり、触媒としての活性も低くなる傾向にある。一方、高すぎる場合は担持された白金はその粒子が粗大化することがあり、その場合はＭＳＡ値が上昇し易くなり好ましくない。 The dinitrodiamine platinum nitric acid aqueous solution may be diluted. The degree of dilution is not particularly limited, but for example, the concentration in terms of metallic platinum is preferably 0.005 to 5 wt%, more preferably 0.005 to 2 wt%. If the platinum concentration is too low, the quality of platinum supported is also low, and the activity as a catalyst tends to be low. On the other hand, if it is too high, the particles of the supported platinum may become coarse, and in that case, the MSA value tends to increase, which is not preferable.
また、本発明方法には、ジニトロジアミン白金硝酸水溶液が使用されるが、得られる触媒の作用を損なわない限り、他の触媒成分や助触媒成分を添加することができる。他の触媒成分としてはパラジウムやロジウム等の金属が挙げられ、助触媒成分としては、金、銅、鉄、ビスマス、バナジウム、クロム等の遷移金属が挙げられる。これら他の触媒成分や助触媒成分は、ジニトロジアミン白金硝酸水溶液の調製時に、上記金属や遷移金属の金属塩の水溶液として添加すればよい。 Further, although a dinitrodiamine platinum nitric acid aqueous solution is used in the method of the present invention, other catalyst components and co-catalyst components can be added as long as the action of the obtained catalyst is not impaired. Examples of other catalyst components include metals such as palladium and rhodium, and examples of co-catalyst components include transition metals such as gold, copper, iron, bismuth, vanadium, and chromium. These other catalyst components and co-catalyst components may be added as an aqueous solution of the metal salt of the metal or transition metal at the time of preparing the dinitrodiamine platinum nitric acid aqueous solution.
（含浸）
本発明方法において、γ−アルミナ担体に、ジニトロジアミン白金硝酸水溶液を含浸させる方法は特に限定されるものではなく、広く当業者において採用されている方法を用いればよい。このような方法としては、γ−アルミナ担体を入れたメッシュ容器を所定濃度のジニトロジアミン白金硝酸水溶液中に浸漬する方法、γ−アルミナ担体が入った回転するドラム容器に所定濃度のジニトロジアミン白金硝酸水溶液を噴霧供給する方法等がある。なお、γ−アルミナ担体にジニトロジアミン白金硝酸水溶液を含浸させた後は、適宜洗浄等をしてもよい。
(Immersion)
In the method of the present invention, the method of impregnating the γ-alumina carrier with the dinitrodiamine platinum nitric acid aqueous solution is not particularly limited, and a method widely adopted by those skilled in the art may be used. Such a method includes a method of immersing a mesh container containing a γ-alumina carrier in a predetermined concentration of dinitrodiamine platinum nitric acid aqueous solution, and a method of immersing a rotating drum container containing the γ-alumina carrier in a predetermined concentration of dinitrodiamine platinum nitric acid. There is a method of spraying and supplying an aqueous solution. After impregnating the γ-alumina carrier with the dinitrodiamine platinum nitric acid aqueous solution, washing or the like may be performed as appropriate.
これらの含浸方法において所定の白金含有量を実現するためには、浸漬する方法で使用するγ−アルミナ担体の飽和含水量からジニトロジアミン白金硝酸水溶液の含浸量を特定し、含浸するジニトロジアミン白金硝酸水溶液の濃度を調整することでγ−アルミナ担体に担持する白金量を調整することができる。一方、噴霧する方法では噴霧するジニトロジアミン白金硝酸水溶液の濃度と噴霧供給量を調整することで多孔質担体に担持する白金量を調整することができる。 In order to achieve a predetermined platinum content in these impregnation methods, the impregnation amount of the dinitrodiamine platinum nitric acid aqueous solution is specified from the saturated water content of the γ-alumina carrier used in the dipping method, and the dinitrodiamine platinum nitric acid to be impregnated is impregnated. By adjusting the concentration of the aqueous solution, the amount of platinum carried on the γ-alumina carrier can be adjusted. On the other hand, in the spraying method, the amount of platinum carried on the porous carrier can be adjusted by adjusting the concentration of the dinitrodiamine platinum nitric acid aqueous solution to be sprayed and the amount of spray supplied.
本発明方法において、γ−アルミナ担体に、ジニトロジアミン白金硝酸水溶液を含浸させる量は用途によって適宜変化するため特に限定されないが、例えば、担体重量あたりの白金含有量が０．１〜５ｗｔ％、好ましくは０．２〜３ｗｔ％である。 In the method of the present invention, the amount of the γ-alumina carrier impregnated with the dinitrodiamine platinum nitric acid aqueous solution varies depending on the application and is not particularly limited. For example, the platinum content per carrier weight is preferably 0.1 to 5 wt%. Is 0.2 to 3 wt%.
なお、上記においては、γ−アルミナ担体にジニトロジアミン白金硝酸水溶液を含浸させる方法について記載しているが、このような含浸法ではなく、本発明方法により得られる高活性白金触媒はウオッシュコート法を用いた触媒の製造にも利用可能であるため、これらを複合化した方法も挙げられる。ウオッシュコート法は金属や無機酸化物からなる構造型担体表面にスラリー化した触媒を被覆する手法の総称である。本発明方法をウオッシュコート法と組合せて実施する場合、本発明方法で得られる高活性白金触媒を水等の溶媒でスラリーとし、それを構造型担体表面に被覆した後に焼成・固定する方法や、γ−アルミナ担体を水等の溶媒でスラリー化したものを使用し、それを構造型担体表面に被覆した後に焼成固定や加熱還元処理を施し、構造型担体に固定した後に高活性白金触媒とする方法等が挙げられる。 In the above, the method of impregnating the γ-alumina carrier with the dinitrodiamine platinum nitric acid aqueous solution is described, but instead of such an impregnation method, the highly active platinum catalyst obtained by the method of the present invention uses the wash coat method. Since it can also be used in the production of the catalyst used, a method in which these are combined can also be mentioned. The wash coat method is a general term for a method of coating a slurryed catalyst on the surface of a structural carrier made of a metal or an inorganic oxide. When the method of the present invention is carried out in combination with the washcoat method, a method in which the highly active platinum catalyst obtained by the method of the present invention is made into a slurry with a solvent such as water, coated on the surface of a structural carrier, and then calcined and fixed. A γ-alumina carrier slurried with a solvent such as water is used, and after coating the surface of the structural carrier, it is calcined and fixed or heat-reduced, and after being fixed on the structural carrier, it is used as a highly active platinum catalyst. The method and the like can be mentioned.
（焼成固定）
本発明方法において、γ−アルミナ担体に、ジニトロジアミン白金硝酸水溶液を含浸させた後、白金成分を焼成固定し、触媒前駆体を調製する。白金成分を焼成固定する方法は特に限定されるものではなく、広く当業者において採用されている方法を用いればよい。このような方法としては、予め触媒前駆体を、大気中８０〜１２０℃程度の温度で乾燥した後、大気中３００〜６００℃で焼成する方法等が挙げられる。触媒前駆体を乾燥した後に焼成することで、担体中の水分が沸騰することで急激に体積を増すことが無く、成型担体であれば担体の破裂を防ぐことができる。乾燥後の焼成温度については低すぎると白金塩の分解が不充分になってしまうことが有り、高すぎるとこの段階で白金がシンタリングを起してしまうことがある。このようにしてγ−アルミナ担体に白金成分を担持させた触媒前駆体が得られる。このようにして得られた触媒前駆体に対しては、必要に応じてイオン交換水による洗浄処理を施しても良い。
(Fixed by firing)
In the method of the present invention, a γ-alumina carrier is impregnated with a dinitrodiamine platinum nitric acid aqueous solution, and then the platinum component is calcined and fixed to prepare a catalyst precursor. The method of firing and fixing the platinum component is not particularly limited, and a method widely adopted by those skilled in the art may be used. Examples of such a method include a method in which the catalyst precursor is previously dried in the air at a temperature of about 80 to 120 ° C. and then calcined in the air at 300 to 600 ° C. By firing the catalyst precursor after it has dried, the volume of the catalyst precursor does not suddenly increase due to boiling of water in the carrier, and if it is a molded carrier, the carrier can be prevented from bursting. If the firing temperature after drying is too low, the decomposition of the platinum salt may be insufficient, and if it is too high, platinum may cause syntering at this stage. In this way, a catalyst precursor in which a platinum component is supported on a γ-alumina carrier can be obtained. The catalyst precursor thus obtained may be washed with ion-exchanged water, if necessary.
（加熱還元処理）
本発明方法において、上記触媒前駆体は、次に水素含有ガスを使用した加熱還元処理を施す。加熱還元処理は、３００〜６００℃の温度下において、水素含有ガスを供給することで行われる。この還元により、白金は前記の焼成工程で酸化した状態から、高活性なメタルの状態に還元される。ここで、水素含有ガスは純水な水素、すなわち水素ガスのみを供給するものであってもよいが、純粋に水素のみからなるガスであると還元操作における制御が難しくなることがあることから、適宜不活性なガスとの混合ガスを用いることが好ましい。このような不活性なガスとしては窒素ガス等が挙げられる。これらの不活性ガスの中でも窒素ガスが好ましい。水素含有ガスとして、例えば、水素ガスと窒素ガスの混合ガスを使用する場合、１気圧における水素ガスと窒素ガスの体積比［Ｈ２／Ｎ２］で［１／２〜１／３０］であることが好ましく、［１／５〜１／１５］であることがより好ましい。水素ガス成分の量が多すぎると還元操作における制御が難しくなることがあり、少なすぎると多量の混合ガスを供給することになり還元雰囲気の温度を上げるのが難しくなることがある。
(Heat reduction treatment)
In the method of the present invention, the catalyst precursor is then subjected to a heat reduction treatment using a hydrogen-containing gas. The heat reduction treatment is performed by supplying a hydrogen-containing gas at a temperature of 300 to 600 ° C. By this reduction, platinum is reduced from the state of being oxidized in the firing step to the state of a highly active metal. Here, the hydrogen-containing gas may supply pure hydrogen, that is, only hydrogen gas, but if the gas is purely hydrogen, it may be difficult to control the reduction operation. It is preferable to use a mixed gas with an inert gas as appropriate. Examples of such an inert gas include nitrogen gas. Among these inert gases, nitrogen gas is preferable. When, for example, a mixed gas of hydrogen gas and nitrogen gas is used as the hydrogen-containing gas, the volume ratio of hydrogen gas and nitrogen gas at 1 atm [H 2 / N 2 ] is [1/2 to 1/30]. It is preferable, and it is more preferable that it is [1/5 to 1/15]. If the amount of the hydrogen gas component is too large, it may be difficult to control the reduction operation, and if it is too small, a large amount of mixed gas will be supplied and it may be difficult to raise the temperature of the reducing atmosphere.
このような水素含有ガスの供給量は特に制限されるものでは無く、還元環境や還元に使用する炉の効率や構造、還元時間、被還元成分の量や状態に応じて適宜設定されるものであるが、被還元成分１ｇあたりの水素ガスの量で１〜２０ｍＬが好ましく、５〜１０ｍＬが好ましい。少なすぎると還元に長時間を要することがあり、多すぎても水素ガスが無駄になったり、還元が急激に進み白金が凝集してしまうことがある。 The amount of such hydrogen-containing gas supplied is not particularly limited, and is appropriately set according to the reduction environment, the efficiency and structure of the furnace used for reduction, the reduction time, and the amount and state of the components to be reduced. However, the amount of hydrogen gas per 1 g of the component to be reduced is preferably 1 to 20 mL, preferably 5 to 10 mL. If it is too small, it may take a long time for reduction, and if it is too large, hydrogen gas may be wasted, or reduction may proceed rapidly and platinum may aggregate.
（加熱還元処理開始温度）
本発明方法においては、上記加熱還元処理において、加熱還元処理を開始する温度は３００〜６００℃、好ましくは４００〜５５０℃とする。従来は、加熱還元処理を開始する温度は、工程管理のし易さから上記触媒前駆体の加熱開始と同時の室温であるが、本発明方法では上記温度とすることにより、γ−アルミナ担体に対して高ＭＳＡな状態で貴金属を担持することが可能になる。また、加熱還元処理を開始するまでは、不活性なガスを供給する。加熱還元処理温度まで昇温する速度については高ＭＳＡな触媒が製造できる範囲であれば特に限定されないが、０．５〜２０℃／分が好ましく、１〜１０℃／分がより好ましい。
(Heating reduction treatment start temperature)
In the method of the present invention, in the heat reduction treatment, the temperature at which the heat reduction treatment is started is set to 300 to 600 ° C, preferably 400 to 550 ° C. Conventionally, the temperature at which the heat reduction treatment is started is the room temperature at the same time as the start of heating of the catalyst precursor because of ease of process control. On the other hand, it becomes possible to support a noble metal in a state of high MSA. In addition, an inert gas is supplied until the heat reduction treatment is started. The rate of raising the temperature to the heat reduction treatment temperature is not particularly limited as long as a high MSA catalyst can be produced, but is preferably 0.5 to 20 ° C./min, more preferably 1 to 10 ° C./min.
このような水素含有ガスの供給温度は高温である方が高いＭＳＡ値、すなわち担体上に担持される白金粒子の表面積は大きくなる傾向がある。ただし、あまりに温度が高すぎると担体が焼結を起してそのＢＥＴ値を低下させてしまう恐れがあるため、本発明における水素含有ガスの供給開始温度は３００〜６００℃であることが必要であり、４００〜５５０℃であることが好ましい。 The higher the supply temperature of such a hydrogen-containing gas, the higher the MSA value, that is, the surface area of the platinum particles supported on the carrier tends to increase. However, if the temperature is too high, the carrier may sinter and lower its BET value. Therefore, the supply start temperature of the hydrogen-containing gas in the present invention needs to be 300 to 600 ° C. It is preferably 400 to 550 ° C.
（加熱還元処理維持温度）
水素含有ガスが供給された還元系では加熱状態を維持することで還元が促進され、焼成によって酸化した白金はメタル化される。加熱状態の維持は加熱還元処理を開始する温度を維持するものであっても良く、場合によっては低下させても良く、更に温度を上昇させてもよいが、焼成された白金の還元を促進する意味では加熱還元処理を開始する温度以上の温度を維持することが好ましい。ただし、あまりに高温であるとメタル化された白金や担体そのものが熱の影響で焼結してＭＳＡ値が小さくなる恐れが有ることから、温度を上昇させる場合であっても６００℃以下が好ましく、５５０℃以下であることがより好ましい。
(Heat reduction treatment maintenance temperature)
In the reduction system to which the hydrogen-containing gas is supplied, the reduction is promoted by maintaining the heated state, and the platinum oxidized by firing is metallized. The maintenance of the heated state may be to maintain the temperature at which the heat reduction treatment is started, may be lowered in some cases, and the temperature may be further raised, but it promotes the reduction of the calcined platinum. In that sense, it is preferable to maintain a temperature equal to or higher than the temperature at which the heat reduction treatment is started. However, if the temperature is too high, the metallized platinum or the carrier itself may be sintered due to the influence of heat and the MSA value may decrease. Therefore, even when the temperature is raised, 600 ° C. or lower is preferable. More preferably, it is 550 ° C. or lower.
（加熱還元処理維持時間）
本発明方法において、水素含有ガスの供給の供給時間、すなわち加熱還元処理時間は特に限定されるものではないが、加熱状態を維持する時間と合わせて０．５〜１５時間であることが好ましく、５〜１０時間であることがより好ましい。時間が短すぎると充分な還元ができないことがあったり、長すぎると水素ガスが無駄になったり、貴金属の粒子径が増大することで反応に有効な活性面積が小さくなって、高価な貴金属を触媒反応に有効に使用できなくなることがある。
(Heat reduction treatment maintenance time)
In the method of the present invention, the supply time of supplying the hydrogen-containing gas, that is, the heat reduction treatment time is not particularly limited, but is preferably 0.5 to 15 hours including the time for maintaining the heated state. More preferably, it is 5 to 10 hours. If the time is too short, sufficient reduction may not be possible, if it is too long, hydrogen gas will be wasted, and the particle size of the noble metal will increase, reducing the effective active area for the reaction, resulting in the use of expensive noble metals. It may not be able to be effectively used for catalytic reactions.
本発明方法における、加熱還元処理開始温度と、加熱還元処理維持温度、加熱還元処理維持時間の好ましい態様は以下の通りである。加熱還元処理開始温度が３００℃を超える場合は、加熱還元処理維持温度は加熱還元処理開始温度を下回っても良い。なお、加熱還元処理維持温度が加熱還元処理開始温度を下回る場合にも、加熱還元処理維持温度は３００℃以上であることが望ましい。
加熱処理開始温度：室温〜１００℃
加熱還元処理開始温度：３００〜６００℃
加熱還元処理維持温度：３００〜６００℃
加熱還元処理維持時間：０．５〜５時間
In the method of the present invention, preferred embodiments of the heat reduction treatment start temperature, the heat reduction treatment maintenance temperature, and the heat reduction treatment maintenance time are as follows. When the heat reduction treatment start temperature exceeds 300 ° C., the heat reduction treatment maintenance temperature may be lower than the heat reduction treatment start temperature. Even when the heat reduction treatment maintenance temperature is lower than the heat reduction treatment start temperature, it is desirable that the heat reduction treatment maintenance temperature is 300 ° C. or higher.
Heat treatment start temperature: room temperature to 100 ° C
Heat reduction treatment start temperature: 300-600 ° C
Heat reduction treatment maintenance temperature: 300-600 ° C
Heat reduction treatment maintenance time: 0.5 to 5 hours
上記加熱還元処理を終了後は、大気中等で放冷することにより、高活性白金触媒が得られる。また、放冷後は、必要に応じて洗浄や助触媒成分の含浸処理等の処理を行ってもよい。 After the heat reduction treatment is completed, a highly active platinum catalyst can be obtained by allowing it to cool in the air or the like. Further, after allowing to cool, treatments such as cleaning and impregnation treatment of co-catalyst components may be performed as necessary.
（高活性白金触媒）
斯くして得られる高活性白金触媒はＭＳＡが高ＭＳＡで担持するものである。具体的に比表面積値が５０〜３００［ｍ２／ｇ］、平均粒径が１〜７ｍｍの球状成型体で、細孔容積が０．４〜０．７ｍＬ／ｇのγ−アルミナ担体であれば、ＭＳＡは３８０ｍ２／ｇ、好ましくは５００ｍ２／ｇとなる。なお、本発明におけるＭＳＡ値は前記のとおり担持された白金の単位重量あたりの表面積を表すものであるが、その測定方法は実施例に記載されている通りである。
(Highly active platinum catalyst)
The highly active platinum catalyst thus obtained is supported by MSA with high MSA. Specifically, a spherical molded body having a specific surface area value of 50 to 300 [m 2 / g] and an average particle size of 1 to 7 mm, and a γ-alumina carrier having a pore volume of 0.4 to 0.7 mL / g. For example, the MSA is 380 m 2 / g, preferably 500 m 2 / g. The MSA value in the present invention represents the surface area per unit weight of the platinum supported as described above, and the measuring method thereof is as described in Examples.
この高活性白金触媒は、そのまま、あるいは、成型等し、あるいは、ハニカム状等の構造型担体に被覆する等して、従来の不均一系の白金触媒と同様に、酸化、還元、脱水素、水素化等の用途に使用することができる。 This highly active platinum catalyst can be oxidized, reduced, dehydrogenated, as it is, molded, or coated on a structural carrier such as a honeycomb, in the same manner as the conventional non-uniform platinum catalyst. It can be used for applications such as hydrogenation.
以下、本発明の実施形態を記すが、本発明は以下の実施例に限定されるものではない。 Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following examples.
また、以下の実施例において、平均粒径はランダムに抜き取った５０粒の実測値の平均値であり、比表面積値は窒素による公知のガス吸着法により測定された値であり、細孔容積は測定圧力４００ＭＰａによる公知の水銀圧入法で測定された値である。 Further, in the following examples, the average particle size is the average value of the measured values of 50 randomly extracted grains, the specific surface area value is the value measured by a known gas adsorption method using nitrogen, and the pore volume is It is a value measured by a known mercury press-fitting method at a measurement pressure of 400 MPa.
実 施 例 １
白金触媒の調製：
（１）熟成ジニトロジアミン白金硝酸溶液の調製
金属白金換算濃度で１８ｗｔ％のジニトロジアミン白金と、硝酸換算で１８ｗｔ％を含むジニトロジアミン白金硝酸溶液を調製した。このジニトロジアミン白金硝酸溶液を容器に密閉して１００℃で３時間維持し、熟成処理を施し、下記の吸光度測定条件で吸光度を測定した。吸光度は０．１７であった。
Example 1
Preparation of platinum catalyst:
(1) Preparation of Aged Dinitrodiamine Platinum Nitric Acid Solution A dinitrodiamine platinum nitric acid solution containing 18 wt% of dinitrodiamine platinum in terms of metal platinum and 18 wt% in terms of nitric acid was prepared. This dinitrodiamine platinum nitric acid solution was sealed in a container and maintained at 100 ° C. for 3 hours, aged, and the absorbance was measured under the following absorbance measurement conditions. The absorbance was 0.17.
＜吸光度測定条件＞
吸光度分析機器：分光光度計Ｕ−３３１０（日立ハイテクサイエンス製）
ジニトロジアミン白金硝酸溶液濃度：元素としての白金換算で１ｇ／Ｌに純水で希釈
光路長：１０ｍｍ
測定波長：４２０ｎｍ
<Absorbance measurement conditions>
Absorbance analyzer: Spectrophotometer U-3310 (manufactured by Hitachi High-Tech Science)
Dinitrodiamine Platinum Nitric acid solution Concentration: Dilute with pure water to 1 g / L in terms of platinum as an element Optical path length: 10 mm
Measurement wavelength: 420 nm
（２）白金触媒の製造
上記ジニトロジアミン白金硝酸溶液を、金属白金換算で０．８ｗｔ％になるように純水で希釈し、下記の担体重量あたりの白金含有量が０．５ｗｔ％となるよう、以下の性質の球状多孔質担体を回転させながら満遍なく含浸させ、１００℃で３０分乾燥後、大気雰囲気下で毎分３．６［℃／ｍｉｎ］で室温〜４５０℃まで昇温した後、４５０℃を維持した状態で５時間焼成して触媒前駆体を得た。
(2) Production of Platinum Catalyst The above dinitrodiamine platinum nitrate solution is diluted with pure water so as to be 0.8 wt% in terms of metallic platinum so that the platinum content per carrier weight below is 0.5 wt%. The spherical porous carrier having the following properties is evenly impregnated while rotating, dried at 100 ° C. for 30 minutes, and then heated to room temperature to 450 ° C. at 3.6 [° C./min] per minute in an air atmosphere. A catalyst precursor was obtained by firing for 5 hours while maintaining 450 ° C.
＜担体物性＞
材質：γ−アルミナ
形状：球状
サイズ：平均粒径 ３．５［ｍｍ］
比表面積値：１６５［ｍ２／ｇ］
細孔容積：０．６２［ｍＬ／ｇ］
<Carrier characteristics>
Material: γ-alumina Shape: Spherical Size: Average particle size 3.5 [mm]
Specific surface area value: 165 [m 2 / g]
Pore volume: 0.62 [mL / g]
このように焼成した触媒前駆体から３０ｇ（約２５粒）を分取し、窒素ガスを毎分１リットル流通させながら２．２５［℃／ｍｉｎ］で昇温し、所定の温度（１００℃、２００℃、３００℃または４００℃）において窒素ガスを下記水素含有ガス組成に切り替えて加熱還元処理を開始し、更に４５０℃まで昇温した後に７時間温度を維持して白金触媒を得た。各加熱還元処理開始温度で得られた白金触媒のＭＳＡ値を以下のようなＣＯ−ＭＳＡ法で測定した。 30 g (about 25 grains) was separated from the catalyst precursor fired in this manner, and the temperature was raised at 2.25 [° C./min] while flowing 1 liter of nitrogen gas per minute to a predetermined temperature (100 ° C., The nitrogen gas was switched to the following hydrogen-containing gas composition at 200 ° C., 300 ° C. or 400 ° C.) to start the heat reduction treatment, and after the temperature was further raised to 450 ° C., the temperature was maintained for 7 hours to obtain a platinum catalyst. The MSA value of the platinum catalyst obtained at each heat reduction treatment start temperature was measured by the following CO-MSA method.
＜水素含有ガス組成＞
・窒素ガス：１．０［Ｌ／ｍｉｎ］
・水素ガス：０．１［Ｌ／ｍｉｎ］
<Hydrogen-containing gas composition>
-Nitrogen gas: 1.0 [L / min]
-Hydrogen gas: 0.1 [L / min]
＜ＭＳＡ値測定方法＞
触媒化されたγ−アルミナに対し、ヘリウム気流下で４０℃まで昇温し、続いて４０℃にて水素ガスに切り替えて還元処理することにより白金表面の酸化層を除去し、その後、ヘリウム気流下で４０℃にし、一酸化炭素（ＣＯ）をパルシブに注入し、その際のＣＯ吸着量を測定した値である。
<MSA value measurement method>
The catalystized γ-alumina is heated to 40 ° C. under a helium stream, and then switched to hydrogen gas at 40 ° C for reduction treatment to remove the oxide layer on the platinum surface, and then the helium stream is used. It is a value obtained by injecting carbon monoxide (CO) into pulsive at 40 ° C. below and measuring the amount of CO adsorbed at that time.
ＭＳＡ値は１００℃で加熱還元処理を開始したものが３４２ｍ２／ｇであり、２００℃で加熱還元処理を開始したものが３５１ｍ２／ｇであり、３００℃で加熱還元処理を開始したものが３８５ｍ２／ｇであり、４００℃で加熱還元処理を開始したものが４０２ｍ２／ｇであった。これらの結果から加熱還元処理の開始温度を３００℃や４００℃とすることで、開始温度が１００℃や２００℃の場合よりもＭＳＡ値が顕著に高くなることが分かった。 The MSA value was 342 m 2 / g when the heat reduction treatment was started at 100 ° C., 351 m 2 / g when the heat reduction treatment was started at 200 ° C., and 351 m 2 / g when the heat reduction treatment was started at 300 ° C. It was 385 m 2 / g, and the one that started the heat reduction treatment at 400 ° C. was 402 m 2 / g. From these results, it was found that when the start temperature of the heat reduction treatment was set to 300 ° C. or 400 ° C., the MSA value was significantly higher than when the start temperature was 100 ° C. or 200 ° C.
なお、加熱還元処理の開始温度とＭＳＡ値をプロットしたところ（図１）、熱還元処理の開始温度が２００℃から３００℃の間で急激にＭＳＡ値が高くなることが分かった。 When the start temperature of the heat reduction treatment and the MSA value were plotted (FIG. 1), it was found that the start temperature of the heat reduction treatment sharply increased between 200 ° C. and 300 ° C.
実 施 例 ２
白金触媒の調製：
（１）ジニトロジアミン白金硝酸溶液の調製
金属白金換算濃度で１８ｗｔ％のジニトロジアミン白金と、硝酸換算で１８ｗｔ％を含むジニトロジアミン白金硝酸溶液を調製した。このジニトロジアミン白金硝酸溶液を実施例１の（１）と同様にして吸光度を測定した。吸光度は０．０５であった。
Example 2
Preparation of platinum catalyst:
(1) Preparation of Dinitrodiamine Platinum Nitric Acid Solution A dinitrodiamine platinum nitric acid solution containing 18 wt% of dinitrodiamine platinum in terms of metal platinum and 18 wt% in terms of nitric acid was prepared. The absorbance of this dinitrodiamine platinum nitric acid solution was measured in the same manner as in (1) of Example 1. The absorbance was 0.05.
（２）白金触媒の製造
上記ジニトロジアミン白金硝酸溶液を用いる以外は実施例１の（２）と同様にして触媒前駆体を得た。
(2) Production of Platinum Catalyst A catalyst precursor was obtained in the same manner as in (2) of Example 1 except that the above dinitrodiamine platinum nitric acid solution was used.
このように焼成した触媒前駆体について、所定の温度を１００℃または４００℃とする以外は実施例１の（２）と同様にして白金触媒を得た。各加熱還元処理開始温度で得られた白金触媒におけるＭＳＡ値を測定した。ＭＳＡ値は１００℃で加熱還元処理を開始したものが２８０ｍ２／ｇであり、４００℃で加熱還元処理を開始したものが４０４ｍ２／ｇであった。 With respect to the catalyst precursor thus calcined, a platinum catalyst was obtained in the same manner as in (2) of Example 1 except that the predetermined temperature was set to 100 ° C. or 400 ° C. The MSA value in the platinum catalyst obtained at each heat reduction treatment start temperature was measured. The MSA value was 280 m 2 / g when the heat reduction treatment was started at 100 ° C. and 404 m 2 / g when the heat reduction treatment was started at 400 ° C.
この結果から、加熱還元処理の開始温度を４００℃とすることで、開始温度が１００℃の場合よりもＭＳＡ値が顕著に高くなることが分かった。 From this result, it was found that when the start temperature of the heat reduction treatment was set to 400 ° C., the MSA value was remarkably higher than that when the start temperature was 100 ° C.
本発明は、酸化、還元、脱水素、水素化等の用途に使用することができる不均一系の白金触媒を製造することができる。
以 上
The present invention can produce a heterogeneous platinum catalyst that can be used for applications such as oxidation, reduction, dehydrogenation, and hydrogenation.
that's all
Claims (5)
加熱還元処理を開始する温度が３００〜６００℃であることを特徴とする高活性白金触媒の製造方法。 After impregnating a γ-alumina carrier with an aqueous solution of dinitrodiamine platinum nitric acid, the platinum component is calcined and fixed to prepare a catalyst precursor, which is then heat-reduced using a hydrogen-containing gas. It ’s a manufacturing method,
A method for producing a highly active platinum catalyst, wherein the temperature at which the heat reduction treatment is started is 300 to 600 ° C.
The method for producing a highly active platinum catalyst according to any one of claims 1 to 4, wherein the dinitrodiamine platinum nitric acid aqueous solution is aged.
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