JP2008000709A - Manufacturing method of heteropoly-acid based catalyst for manufacturing methacrylic acid - Google Patents

Manufacturing method of heteropoly-acid based catalyst for manufacturing methacrylic acid Download PDF

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JP2008000709A
JP2008000709A JP2006174014A JP2006174014A JP2008000709A JP 2008000709 A JP2008000709 A JP 2008000709A JP 2006174014 A JP2006174014 A JP 2006174014A JP 2006174014 A JP2006174014 A JP 2006174014A JP 2008000709 A JP2008000709 A JP 2008000709A
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catalyst
methacrylic acid
heteropolyacid
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acid
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Tomohiro Masaki
朋博 柾
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Mitsubishi Rayon Co Ltd
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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
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Abstract

<P>PROBLEM TO BE SOLVED: To easily and inexpensively manufacture a heteropoly-acid based catalyst for manufacturing methacrylic acid from the used heteropoly-acid based catalyst for manufacturing methacrylic acid at a yield of 90% ore higher relative to an unused one. <P>SOLUTION: The manufacturing method of the heteropoly-acid based catalyst for manufacturing methacrylic acid has a separation step for contacting the used heteropoly-acid based catalyst containing one kind or more of elements selected from the group consisting of cesium, potassium, thallium and rubidium and molybdenum and used for manufacturing of methacrylic acid by vapor phase contact oxidation with an aqueous medium of pH 1 to less than pH 8, and solid/liquid-separating the obtained dispersion to a liquid component and a solid recovery component, and a catalyst preparation step for preparing the heteropoly-acid based catalyst for manufacturing methacrylic acid making the solid recovery component as a material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、気相接触酸化によるメタクリル酸の製造に使用されるヘテロポリ酸系触媒の製造方法に関する。   The present invention relates to a method for producing a heteropolyacid catalyst used for producing methacrylic acid by gas phase catalytic oxidation.

メタクロレインを気相接触酸化してメタクリル酸を製造する際に使用される触媒としてヘテロポリ酸系触媒がある。
このようなヘテロポリ酸系触媒としては、例えばモリブドリン酸、モリブドバナドリン酸など、カウンターカチオンがプロトンであるヘテロポリ酸と、そのプロトンの一部をセシウム、ルビジウム、タリウム、カリウムなどで置換し、ヘテロポリ酸塩にしたものとが知られている。ヘテロポリ酸は酸性度が高いため、これを単独で触媒として使用するとメタクリル酸の選択率が低くなる。そこで、プロトンの一部を部分中和することにより酸性度を調整したものを触媒とすることが特許文献１に記載されている。 There is a heteropolyacid catalyst as a catalyst used in producing methacrylic acid by vapor phase catalytic oxidation of methacrolein.
Such heteropolyacid catalysts include, for example, heteropolyacids whose counter cations are protons, such as molybdophosphoric acid and molybdovanadolinic acid, and a portion of the protons substituted with cesium, rubidium, thallium, potassium, etc. The acid salt is known. Since the heteropolyacid has a high acidity, when it is used alone as a catalyst, the selectivity of methacrylic acid is lowered. Therefore, Patent Document 1 describes that a catalyst whose acidity is adjusted by partially neutralizing a part of protons is used.

なお、カウンターカチオンがプロトンであるヘテロポリ酸は水溶性であるが、プロトンがセシウム、ルビジウム、タリウム、カリウムのうちの少なくとも１種で置換されたヘテロポリ酸塩は、一般に水に難溶性である。これら元素のカチオンのイオン半径は１．１Å以上であり、このことが難溶性と相関があるとされ、例えば特許文献２でもヘテロポリ酸の沈殿剤として記載されている。
以下、カウンターカチオンがプロトンだけであるヘテロポリ酸を「Ｈ−へテロポリ酸」と言い、カウンターカチオンがセシウム、ルビジウム、タリウム、カリウムのうちの少なくとも１種であるヘテロポリ酸塩を「難溶性ヘテロポリ酸塩」という場合がある。 In addition, although the heteropoly acid whose counter cation is a proton is water-soluble, the heteropoly acid salt in which the proton is substituted with at least one of cesium, rubidium, thallium and potassium is generally poorly soluble in water. The ionic radius of the cation of these elements is 1.1 Å or more, and this is considered to correlate with poor solubility. For example, Patent Document 2 also describes as a heteropolyacid precipitant.
Hereinafter, a heteropoly acid whose counter cation is only a proton is referred to as “H-heteropoly acid”, and a heteropoly acid salt whose counter cation is at least one of cesium, rubidium, thallium, and potassium is referred to as a “slightly soluble heteropoly acid salt”. "

ヘテロポリ酸系触媒は、メタクリル酸製造時の熱や還元雰囲気などにより分解して分解生成物を生じ、その結果、経時的にメタクリル酸収率が低下することが知られている。そのため、このようにメタクリル酸収率が低下した使用済みのヘテロポリ酸系触媒を有効に使用して、新たなヘテロポリ酸系触媒を製造する技術について種々検討されている。   It is known that a heteropolyacid catalyst is decomposed by heat or a reducing atmosphere during the production of methacrylic acid to produce a decomposition product, and as a result, the yield of methacrylic acid decreases with time. For this reason, various studies have been conducted on techniques for producing new heteropolyacid catalysts by effectively using a used heteropolyacid catalyst having a reduced methacrylic acid yield.

特許文献３には、難溶性ヘテロポリ酸塩から水溶性のヘテロポリ酸や元素の回収をするために、使用済みのヘテロポリ酸系触媒を水に分散させた後、好ましくはｐＨ８以上となる量の水酸化ナトリウム水溶液やアンモニウム水を加えた液を得て、さらに、酸を加えてｐＨ６．５以下に調整して沈殿させる方法が記載されている。この方法は、水酸化ナトリウム水溶液やアンモニア水を加えた液をイオン交換樹脂に通す工程やｐＨ調整を繰り返し行う工程などが必要であり、工程が煩雑であった。このように煩雑な方法では、手間がかかるうえ消費エネルギーコストも高くなるため、使用済み触媒を有効に利用する技術としては好適ではなかった。
特開平０８−１００５号公報 特開平０７−２１３９２２号公報 特開２００１−２９７９９号公報 Patent Document 3 discloses that in order to recover a water-soluble heteropolyacid or element from a hardly soluble heteropolyacid salt, a used heteropolyacid catalyst is dispersed in water, and then an amount of water that preferably has a pH of 8 or more is disclosed. A method is described in which a solution obtained by adding an aqueous solution of sodium oxide or aqueous ammonium is added, and further, an acid is added to adjust the pH to 6.5 or lower for precipitation. This method requires a process of passing a solution containing an aqueous sodium hydroxide solution or aqueous ammonia through an ion exchange resin, a process of repeatedly adjusting pH, and the like, and the process is complicated. Such a complicated method is not suitable as a technique for effectively using a used catalyst because it takes time and increases the energy consumption cost.
Japanese Patent Laid-Open No. 08-1005 JP 07-213992 A JP 2001-29799 A

本発明は上記事情に鑑みてなされたもので、使用済みのメタクリル酸製造用ヘテロポリ酸系触媒から、簡単かつ低コストに、未使用触媒に対して９０％以上のメタクリル酸収率を発揮するメタクリル酸製造用ヘテロポリ酸系触媒を製造することを課題とする。   The present invention has been made in view of the above circumstances. From a used heteropolyacid catalyst for producing methacrylic acid, methacrylic acid yielding a methacrylic acid yield of 90% or more with respect to an unused catalyst is simple and low-cost. An object is to produce a heteropolyacid catalyst for acid production.

本発明のヘテロポリ酸系触媒の製造方法は、気相接触酸化によるメタクリル酸の製造に使用されるヘテロポリ酸系触媒の製造方法において、セシウム、カリウム、タリウム、ルビジウムからなる群より選ばれる１種以上の元素とモリブデンを含有し、気相接触酸化によるメタクリル酸の製造に使用された使用済みヘロポリ酸系触媒をｐＨ１以上、ｐＨ８未満の水性媒体と接触させ、得られた分散液を液体成分と固体回収成分とに固液分離する分離工程と、前記固体回収成分を原料としてメタクリル酸製造用ヘテロポリ酸系触媒を調製する触媒調製工程とを有することを特徴とする。   The method for producing a heteropolyacid catalyst of the present invention is one or more selected from the group consisting of cesium, potassium, thallium and rubidium in the method for producing a heteropolyacid catalyst used in the production of methacrylic acid by gas phase catalytic oxidation. A used heropolyacid catalyst containing molybdenum element and molybdenum and used for the production of methacrylic acid by gas phase catalytic oxidation is brought into contact with an aqueous medium having a pH of 1 or more and less than 8, and the resulting dispersion is treated with a liquid component and a solid. It comprises a separation step for solid-liquid separation into a recovery component and a catalyst preparation step for preparing a heteropolyacid catalyst for methacrylic acid production using the solid recovery component as a raw material.

前記触媒調製工程は、前記固体回収成分に追加成分を加える成分追加工程と、成分追加工程で得られた混合物を焼成する焼成工程とを有していることが好ましい。
製造される前記メタクリル酸製造用ヘテロポリ酸系触媒は、下記式（１）で表される組成を有することが好ましい。
ＡaＭｏbＶcＣｕdＤeＹfＺgＯh （１）
（式中のＭｏ、Ｖ、ＣｕおよびＯは、それぞれがモリブデン、バナジウム、銅および酸素を示し、Ａはリン、ヒ素からなる群より選ばれた少なくとも１種の元素を示し、Ｄはアンチモン、ビスマス、ゲルマニウム、ジルコニウム、テルル、銀、セレン、珪素、タングステンおよびホウ素からなる群より選ばれた少なくとも１種の元素を示し、Ｙは鉄、亜鉛、クロム、マグネシウム、タンタル、マンガン、コバルト、バリウム、ガリウム、セリウムおよびランタンからなる群より選ばれた少なくとも１種の元素を示し、Ｚはナトリウム、カリウム、ルビジウム、セシウムおよびタリウムからなる群より選ばれた少なくとも１種の元素を示す。ａ，ｂ，ｃ，ｄ，ｅ，ｆ，ｇ，およびｈは各元素の原子比率で表し、ｂ＝１２のときａ＝０．５〜３、ｃ＝０．０１〜３、ｄ＝０〜２、ｅ＝０〜３、ｆ＝０〜３、ｇ＝０．０１〜３であり、ｈは前記各成分の原子価を満足するのに必要な酸素の原子比率である。） The catalyst preparation step preferably includes a component addition step of adding an additional component to the solid recovery component and a firing step of firing the mixture obtained in the component addition step.
The produced heteropolyacid catalyst for producing methacrylic acid preferably has a composition represented by the following formula (1).
A a Mo b V c Cu d De Y f Z g O h (1)
(In the formula, Mo, V, Cu and O respectively represent molybdenum, vanadium, copper and oxygen, A represents at least one element selected from the group consisting of phosphorus and arsenic, and D represents antimony, bismuth. And at least one element selected from the group consisting of germanium, zirconium, tellurium, silver, selenium, silicon, tungsten and boron, Y is iron, zinc, chromium, magnesium, tantalum, manganese, cobalt, barium, gallium , Z represents at least one element selected from the group consisting of cerium and lanthanum, and Z represents at least one element selected from the group consisting of sodium, potassium, rubidium, cesium and thallium. , D, e, f, g, and h are represented by atomic ratios of the respective elements, and when b = 12, a = 0.5 to 3, = 0.01 to 3, d = 0 to 2, e = 0 to 3, f = 0 to 3, g = 0.01 to 3, and h is necessary to satisfy the valence of each component. (The atomic ratio of oxygen.)

本発明によれば、使用済みのメタクリル酸製造用ヘテロポリ酸系触媒から、簡単かつ低コストに、未使用触媒に対して９０％以上のメタクリル酸収率を発揮するメタクリル酸製造用ヘテロポリ酸系触媒を製造できる。   According to the present invention, a heteropolyacid catalyst for methacrylic acid production that exhibits a methacrylic acid yield of 90% or more with respect to an unused catalyst is simple and low-cost from a used heteropolyacid catalyst for methacrylic acid production. Can be manufactured.

以下、本発明を詳細に説明する。
本発明は、気相接触酸化によるメタクリル酸の製造に使用されるヘテロポリ酸系触媒の製造方法であって、気相接触酸化によるメタクリル酸の製造に使用された使用済みヘテロポリ酸系触媒（以下、単に使用済み触媒という。）を水などのｐＨ１以上、ｐＨ８未満の水性媒体と接触させ、得られた分散液を液体成分と固体回収成分とに固液分離する分離工程を有する。 Hereinafter, the present invention will be described in detail.
The present invention relates to a method for producing a heteropolyacid catalyst used for the production of methacrylic acid by gas phase catalytic oxidation, which is a used heteropolyacid catalyst (hereinafter, Simply having a spent catalyst) contacted with an aqueous medium having a pH of 1 or more and less than pH 8, such as water, and the resulting dispersion is separated into a liquid component and a solid recovery component.

ここで使用済み触媒とは、セシウム、カリウム、タリウム、ルビジウムからなる群より選ばれる１種以上の元素とモリブデンを含有し、メタクロレイン、イソブタン、イソ酪酸、イソブチルアルデヒドなどを気相接触酸化してメタクリル酸を製造する際に使用されたものであれば制限はなく、メタクリル酸収率などの触媒性能が明確に低下していないものでもよい。反対に、メタクリル酸製造時の反応温度を上げるなどメタクリル酸収率に有利な反応条件変更を行っても、メタクリル酸収率の維持が困難となったような劣化の進行した触媒であってもよい。   Here, the used catalyst contains one or more elements selected from the group consisting of cesium, potassium, thallium, and rubidium and molybdenum, and gas phase catalytic oxidation of methacrolein, isobutane, isobutyric acid, isobutyraldehyde, and the like. If it was used when manufacturing methacrylic acid, there will be no restriction | limiting, The catalyst performance, such as a methacrylic acid yield, may not fall clearly. On the other hand, even if the reaction conditions are changed favorably for the methacrylic acid yield, such as raising the reaction temperature during the production of methacrylic acid, even if the catalyst has deteriorated so that it is difficult to maintain the methacrylic acid yield. Good.

使用済み触媒は、触媒活性成分であるＨ−ヘテロポリ酸と、そのプロトンの一部がプロトン以外のカチオンで置換された低活性成分のヘテロポリ酸塩とを含有する。
これらＨ−ヘテロポリ酸およびヘテロポリ酸塩のポリ原子としては、少なくともモリブデンが含まれ、その他にはバナジウム、アンチモン、タングステン、ニオブなどを含んでいてもよい。また、使用済み触媒は、ヘテロ原子として、例えばリン、ヒ素、珪素、イオウ、窒素、テルル、アンチモン、セリウムなどヘテロ原子になり得る元素を少なくとも１種含有する。 The spent catalyst contains an H-heteropolyacid that is a catalytically active component and a low-activity component heteropolyacid salt in which a part of the proton is replaced with a cation other than the proton.
The poly atom of these H-heteropolyacid and heteropolyacid salt contains at least molybdenum, and may contain vanadium, antimony, tungsten, niobium and the like. The spent catalyst contains at least one element that can be a heteroatom such as phosphorus, arsenic, silicon, sulfur, nitrogen, tellurium, antimony, cerium, and the like as a heteroatom.

ヘテロポリ酸塩を構成するカウンターカチオンには、セシウム、カリウム、タリウム、ルビジウムからなる群より選ばれる１種以上の元素のカチオンが少なくとも含まれ、これらカチオンにより、Ｈ−ヘテロポリ酸のプロトンの一部が置換されている。置換体としては、例えば１置換体、２置換体、３置換体などがあり、これらが混在していることもある。また、場合によっては、カチオンとして、セシウム、カリウム、タリウム、ルビジウム以外のカチオン、例えばアンモニウムイオンなどが含まれる場合もある。   The counter cation constituting the heteropolyacid salt includes at least a cation of one or more elements selected from the group consisting of cesium, potassium, thallium, and rubidium, and by these cations, a part of the protons of the H-heteropolyacid is formed. Has been replaced. Examples of the substituted body include a 1-substituted body, a 2-substituted body, a 3-substituted body, and the like, and these may be mixed. In some cases, cations may include cations other than cesium, potassium, thallium, and rubidium, such as ammonium ions.

さらに、使用済み触媒には、その触媒の製造工程に由来するヘテロポリ酸を構成しないフリーの化合物、メタクリル酸製造時の熱や還元雰囲気などにより生成した分解生成物も通常は含まれる。分解生成物としては、ヘテロポリ酸系触媒を構成している金属元素の酸（モリブデン酸の他、例えばリン酸、バナジン酸、ヒ酸などであり、以下、金属酸ともいう。）がある。   Further, the spent catalyst usually includes a free compound that does not constitute a heteropolyacid derived from the production process of the catalyst, and a decomposition product produced by heat, a reducing atmosphere, or the like during the production of methacrylic acid. Examples of the decomposition products include metal element acids constituting the heteropolyacid catalyst (in addition to molybdic acid, for example, phosphoric acid, vanadic acid, arsenic acid, and the like, hereinafter also referred to as metal acids).

分離工程において、このような使用済み触媒を水性媒体と接触させた場合、使用済み触媒に含まれるＨ−ヘテロポリ酸や分解生成物である上述の金属酸、フリーの化合物などは水性媒体に溶解しやすいが、セシウム、カリウム、タリウム、ルビジウムのヘテロポリ酸塩は水に難溶性であることが多く、水性媒体にはほとんど溶解しない。
よって、使用済み触媒を水性媒体と接触させ、得られた分散液を液体成分と固体回収成分とに固液分離することにより、カウンターカチオンがセシウム、カリウム、タリウム、ルビジウムからなる群より選ばれる１種以上のヘテロポリ酸塩を主に含有し、Ｈ−ヘテロポリ酸や分解生成物をほとんど含有しない固体回収成分を得ることができる。通常、固体回収成分のうちの８０質量％以上が難溶性ヘテロポリ酸塩である。
水性媒体としては、水、水溶液、含水アルコールなどが挙げられるが、ｐＨは１以上、８未満であることが必要であり、１〜７であることが好ましく、より好ましくは１〜６である。ｐＨの調整は、例えば水に硝酸などの酸を加える方法、水道水をイオン交換処理する方法などにより行うことができるが、後者が簡便である。 In the separation step, when such a spent catalyst is brought into contact with an aqueous medium, the H-heteropolyacid contained in the spent catalyst, the above-mentioned metal acid as a decomposition product, free compounds, etc. are dissolved in the aqueous medium. Although easy, heteropolyacid salts of cesium, potassium, thallium, and rubidium are often poorly soluble in water and hardly dissolve in aqueous media.
Therefore, the counter cation is selected from the group consisting of cesium, potassium, thallium and rubidium by bringing the spent catalyst into contact with an aqueous medium and solid-liquid separating the resulting dispersion into a liquid component and a solid recovery component. It is possible to obtain a solid recovery component mainly containing at least a heteropoly acid salt of a species and containing almost no H-heteropolyacid or decomposition product. Usually, 80% by mass or more of the solid recovery component is a hardly soluble heteropolyacid salt.
Examples of the aqueous medium include water, an aqueous solution, a hydrous alcohol, and the like. The pH needs to be 1 or more and less than 8, preferably 1 to 7, and more preferably 1 to 6. The pH can be adjusted by, for example, a method of adding an acid such as nitric acid to water or a method of ion-exchanging tap water, but the latter is convenient.

分離工程において、水などの水性媒体とこれと接触させる使用済み触媒との比率には特に制限はなく、この触媒の水性媒体に対する分散性や溶解性の他、分散液の撹拌性や、使用済み触媒が加水分解しにくいような比率であること（例えば、日本化学会誌、１９８５（１２），ｐ．２２３７〜２２４５参照）などを勘案して決定すればよいが、水性媒体１００質量部に対して使用済み触媒０．１〜５０質量部の範囲が好ましい。さらに分散液の粘度や分離工程の効率性などを考慮すると、より好ましくは１〜３０質量部である。
また、水性媒体と使用済み触媒とを接触させる際のスケールにも特に制限はなく、１００ｇ程度の小スケールから数１０ｍ３の工業スケールまで、いかなるスケールで実施してもよい。 In the separation step, there is no particular limitation on the ratio of the aqueous medium such as water and the used catalyst to be brought into contact therewith. In addition to the dispersibility and solubility of the catalyst in the aqueous medium, the stirring ability of the dispersion and the used catalyst are used. The ratio is determined so that the catalyst is difficult to hydrolyze (see, for example, Journal of Chemical Society of Japan, 1985 (12), p. 2237 to 2245). A range of 0.1 to 50 parts by weight of the used catalyst is preferable. Furthermore, when considering the viscosity of the dispersion and the efficiency of the separation step, it is more preferably 1 to 30 parts by mass.
Moreover, there is no restriction | limiting in particular in the scale at the time of making an aqueous medium and a used catalyst contact, You may implement in any scale from the small scale of about 100 g to the industrial scale of several tens of m < 3 >.

水性媒体と使用済み触媒を接触させる際の温度にも特に制限はなく、その環境温度などに応じて決定すればよいが、加熱をしない常温付近であってもＨ−ヘテロポリ酸や金属酸などの水溶性成分は水性媒体に十分に溶解する点、９０℃以下であっても水性媒体の温度が高くなるとヘテロポリ酸系触媒が加水分解する可能性がある点（例えば、日本化学会誌、１９８６（２），ｐ．１２０〜１２５参照）などから、１〜４０℃が好ましい。   The temperature at which the aqueous medium and the used catalyst are brought into contact with each other is not particularly limited, and may be determined according to the environmental temperature. However, H-heteropolyacid, metal acid, etc. may be used even near room temperature without heating. The water-soluble component is sufficiently soluble in an aqueous medium, and even when the temperature is 90 ° C. or lower, the heteropolyacid catalyst may be hydrolyzed when the temperature of the aqueous medium increases (for example, Journal of Chemical Society of Japan, 1986 (2 ), P.120-125), etc., from 1 to 40 ° C. is preferable.

使用済み触媒を水性媒体と接触させる方法としては、使用済み触媒を水性媒体に加える方法、水性媒体を使用済み触媒に加える方法、使用済み触媒に水性媒体を噴霧する方法などが挙げられる。また、使用済み触媒と水性媒体を接触させてから、得られた分散液を液体成分と固体回収成分とに固液分離するまでの間、撹拌装置により撹拌してもよい。撹拌時間には特に制限はないが、３０分間以下で十分である。   Examples of the method of bringing the used catalyst into contact with the aqueous medium include a method of adding the used catalyst to the aqueous medium, a method of adding the aqueous medium to the used catalyst, and a method of spraying the aqueous catalyst onto the used catalyst. Moreover, you may stir with a stirring apparatus after making a used catalyst and an aqueous medium contact, and carrying out solid-liquid separation of the obtained dispersion into a liquid component and a solid collection | recovery component. There is no particular limitation on the stirring time, but 30 minutes or less is sufficient.

分散液を固液分離する方法としては、ろ過法、遠心分離法、自然沈降法など、通常の固液分離法のなかから適宜採用すればよいが、小スケールの場合には、固液分離を迅速に行えることから遠心分離が好ましく、遠心分離の条件としては、例えば回転数１２，０００〜１８，０００ｒｐｍで、１〜２０分間などの条件が好適である。一方、工業スケールの場合には、消費エネルギーが少なくて済むことから、自然沈降法を採用し、上層の液体成分を抜き出した後、底部に溜まった固体回収成分を回収する方法が好ましい。この場合、固体回収成分をそのまま次の触媒調製工程に使用してもよいし、ろ過法により液体成分を十分に除去してから使用してもよい。   As a method for solid-liquid separation of the dispersion liquid, it may be appropriately adopted from ordinary solid-liquid separation methods such as filtration, centrifugation, and natural sedimentation. Centrifugation is preferable because it can be carried out quickly. As the conditions for the centrifugation, for example, conditions of 12,000 to 18,000 rpm and 1 to 20 minutes are suitable. On the other hand, in the case of an industrial scale, it is preferable to use a natural sedimentation method and extract a liquid component in the upper layer and then recover a solid recovery component accumulated at the bottom portion because less energy is consumed. In this case, the solid recovery component may be used as it is in the next catalyst preparation step, or may be used after sufficiently removing the liquid component by a filtration method.

触媒調製工程は、分離工程で得られた固体回収成分を原料として使用して、メタクリル酸製造用ヘテロポリ酸系触媒を調製する工程である。
ここで固体回収成分は、上述したように、カウンターカチオンがセシウム、カリウム、タリウム、ルビジウムからなる群より選ばれる１種以上である難溶性ヘテロポリ酸塩を主成分とするものであって、触媒としては低活性な成分である。
よって、触媒調製工程では、このような固体回収成分に対して、触媒として高活性な成分、好ましくはＨ−ヘテロポリ酸を主とする成分を追加成分として加えてから（成分追加工程）、この成分追加工程で得られた混合物を必要に応じて乾燥し（乾燥工程）、焼成する（焼成工程）ことが好ましい。なお、成分追加工程の前には、固体回収成分を４０〜１６０℃に保持された真空乾燥機などで一昼夜程度乾燥してもよい。 The catalyst preparation step is a step of preparing a heteropolyacid catalyst for methacrylic acid production using the solid recovery component obtained in the separation step as a raw material.
Here, as described above, the solid recovery component is mainly composed of a hardly soluble heteropolyacid salt whose counter cation is one or more selected from the group consisting of cesium, potassium, thallium, and rubidium, as a catalyst. Is a low activity ingredient.
Therefore, in the catalyst preparation step, a component having high activity as a catalyst, preferably a component mainly composed of H-heteropolyacid is added as an additional component to such a solid recovery component (component addition step), and then this component. It is preferable that the mixture obtained in the additional step is dried as necessary (drying step) and fired (firing step). In addition, before a component addition process, you may dry a solid collection | recovery component about a day and night with a vacuum dryer etc. which were hold | maintained at 40-160 degreeC.

成分追加工程を実施するにあたっては、実際には、分離工程で得られた固体回収成分をＩＣＰ発光分析法、蛍光Ｘ線分析法、原子吸光分析法などで元素分析し、得られた元素分析結果に応じて、目的とする組成から追加すべき追加成分を決定することが好ましい。より好ましくは、製造されるヘテロポリ酸系触媒が下記式（１）で表される組成となるように、追加成分を追加することが好ましい。式（１）のような組成のヘテロポリ酸系触媒であれば、メタクロレインからメタクリル酸を高収率で得ることができる。   In conducting the component addition process, the solid recovery component obtained in the separation process is actually subjected to elemental analysis by ICP emission analysis, X-ray fluorescence analysis, atomic absorption analysis, etc., and the obtained elemental analysis results Accordingly, it is preferable to determine additional components to be added from the target composition. More preferably, it is preferable to add an additional component so that the produced heteropolyacid catalyst has a composition represented by the following formula (1). With a heteropolyacid catalyst having a composition as represented by formula (1), methacrylic acid can be obtained from methacrolein in high yield.

ＡaＭｏbＶcＣｕdＤeＹfＺgＯh （１）
（式中のＭｏ、Ｖ、ＣｕおよびＯは、それぞれがモリブデン、バナジウム、銅および酸素を示し、Ａはリン、ヒ素からなる群より選ばれた少なくとも１種の元素を示し、Ｄはアンチモン、ビスマス、ゲルマニウム、ジルコニウム、テルル、銀、セレン、珪素、タングステンおよびホウ素からなる群より選ばれた少なくとも１種の元素を示し、Ｙは鉄、亜鉛、クロム、マグネシウム、タンタル、マンガン、コバルト、バリウム、ガリウム、セリウムおよびランタンからなる群より選ばれた少なくとも１種の元素を示し、Ｚはナトリウム、カリウム、ルビジウム、セシウムおよびタリウムからなる群より選ばれた少なくとも１種の元素を示す。ａ，ｂ，ｃ，ｄ，ｅ，ｆ，ｇ，およびｈは各元素の原子比率で表し、ｂ＝１２のときａ＝０．５〜３、ｃ＝０．０１〜３、ｄ＝０〜２、ｅ＝０〜３、ｆ＝０〜３、ｇ＝０．０１〜３であり、ｈは前記各成分の原子価を満足するのに必要な酸素の原子比率である。） A a Mo b V c Cu d De Y f Z g O h (1)
(In the formula, Mo, V, Cu and O respectively represent molybdenum, vanadium, copper and oxygen, A represents at least one element selected from the group consisting of phosphorus and arsenic, and D represents antimony, bismuth. And at least one element selected from the group consisting of germanium, zirconium, tellurium, silver, selenium, silicon, tungsten and boron, Y is iron, zinc, chromium, magnesium, tantalum, manganese, cobalt, barium, gallium , Z represents at least one element selected from the group consisting of cerium and lanthanum, and Z represents at least one element selected from the group consisting of sodium, potassium, rubidium, cesium and thallium. , D, e, f, g, and h are represented by atomic ratios of the respective elements, and when b = 12, a = 0.5 to 3, = 0.01 to 3, d = 0 to 2, e = 0 to 3, f = 0 to 3, g = 0.01 to 3, and h is necessary to satisfy the valence of each component. (The atomic ratio of oxygen.)

蛍光Ｘ線分析法は乾燥粉で測定できるが、ＩＣＰ発光分析法、原子吸光分析法などで元素分析する際には、まず、試料約０．１ｇと、２５〜２８質量％アンモニア水０．５ｍｌと、純水約２０ｍｌとを超音波照射しながら混合し、試料が完全に溶解した溶液を調製する。そしてこれを適当な倍率に希釈して、上記分析法に供することが好適である。   X-ray fluorescence analysis can be performed with dry powder, but when elemental analysis is performed by ICP emission spectrometry, atomic absorption spectrometry, etc., first, about 0.1 g of sample and 25-28% by mass of ammonia water 0.5 ml And about 20 ml of pure water while mixing with ultrasonic waves to prepare a solution in which the sample is completely dissolved. And it is suitable to dilute this to a suitable magnification and to use for the said analysis method.

成分追加工程における追加成分の追加方法としては、例えば追加成分が水などの水性媒体中に溶解または分散した液状物を調製し、これを固体回収成分と混合してスラリーとする湿式混合法や、固体状の追加成分を固体回収成分と混合する乾式混合法が挙げられる。しかしながら、追加成分と固体回収成分とが良好に分散し、表面の化学状態や酸点などが均質なヘテロポリ酸系触媒が得られやすいことから、追加成分を液状物として固体回収成分と混合する湿式混合法がより好適である。特にＨ−ヘテロポリ酸及び／またはその前駆体であるアンモニウムのヘテロポリ酸塩を湿式混合法で固体回収成分に追加して得られたヘテロポリ酸系触媒によれば、Ｈ−ヘテロポリ酸の有する高活性点と、固体回収成分中の難溶性ヘテロポリ酸塩の有する低活性点とが高分散し、メタクロレインの燃焼反応が抑制された適度な活性を実現できる。   As a method for adding an additional component in the component addition step, for example, a wet mixing method in which a liquid material in which an additional component is dissolved or dispersed in an aqueous medium such as water is prepared, and this is mixed with a solid recovery component to form a slurry, Examples include a dry mixing method in which a solid additional component is mixed with a solid recovery component. However, since the additional component and the solid recovery component are well dispersed and it is easy to obtain a heteropolyacid-based catalyst having a uniform surface chemical state and acid point, etc., a wet process in which the additional component is mixed with the solid recovery component as a liquid substance. A mixing method is more preferred. In particular, according to the heteropolyacid catalyst obtained by adding the heteropolyacid salt of H-heteropolyacid and / or its precursor heteropolyacid salt to the solid recovery component by the wet mixing method, the high activity point of the H-heteropolyacid is obtained. And the low active point which the poorly soluble heteropoly acid salt in a solid collection | recovery component disperses highly, and can implement | achieve the moderate activity by which the combustion reaction of methacrolein was suppressed.

Ｈ−ヘテロポリ酸を追加成分とする場合には、公知の方法でＨ−ヘテロポリ酸を合成し、これを固体回収成分に追加すればよい。Ｈ−ヘテロポリ酸の合成方法としては、これを構成する元素の塩、酸などを原料とし、これを水に溶解し、その後加熱撹拌しながら蒸発乾固する蒸発乾固法の他、水熱合成法、固相反応法などがある。   When an H-heteropolyacid is used as an additional component, the H-heteropolyacid may be synthesized by a known method and added to the solid recovery component. The synthesis method of H-heteropolyacid includes a salt, acid, etc. constituting the raw material, dissolved in water and then evaporated to dryness with heating and stirring, as well as hydrothermal synthesis. Method and solid phase reaction method.

追加成分を湿式混合法で追加した場合には、例えば、得られたスラリーを蒸発乾固し、その水分の大部分を除去した後、乾燥する。乾燥方法は特に限定されず、蒸発乾固法、噴霧乾燥法、ドラム乾燥法、気流乾燥法などの方法が挙げられる。この際に使用する乾燥機の機種や乾燥温度などの条件は特に限定されず、所望する乾燥品の形状や大きさにより適宜選択することができる。そして、乾燥工程で得られた乾燥品を空気などの酸素含有雰囲気下、２００〜５００℃、好ましくは３００〜４５０℃で０．５時間以上、好ましくは１〜４０時間の条件で焼成する（焼成工程）ことにより、メタクリル酸製造用ヘテロポリ酸系触媒を製造することができる。
追加成分の追加を乾式混合法で行った場合には、得られた混合物に対して、必要に応じて上述の乾燥工程を実施した後、焼成工程を実施すればよい。
なお、焼成工程の前には、固体回収成分と追加成分との混合物やその乾燥品を顆粒状に整粒してもよい。整粒の方法としては、混合物や乾燥品を加圧成形した後破砕し、さらに篩分して、特定の範囲に分級された顆粒のみを採用する方法が挙げられる。また、成型品にしてもよく、その場合は、例えば、得られた乾燥品を打錠成型機により、外径５ｍｍ、内径２ｍｍ、長さ５ｍｍのリング状に成型する。そして、この成型品を空気流通下、３８０℃にて１２時間焼成することにより、メタクリル酸製造用触媒を得ることができる。 When the additional component is added by a wet mixing method, for example, the obtained slurry is evaporated to dryness, and most of the moisture is removed, followed by drying. The drying method is not particularly limited, and examples thereof include methods such as evaporation to dryness, spray drying, drum drying, and airflow drying. The conditions such as the model of the dryer used at this time and the drying temperature are not particularly limited, and can be appropriately selected depending on the desired shape and size of the dried product. Then, the dried product obtained in the drying step is fired in an oxygen-containing atmosphere such as air at 200 to 500 ° C., preferably 300 to 450 ° C. for 0.5 hour or longer, preferably 1 to 40 hours (baking) Step), a heteropolyacid catalyst for methacrylic acid production can be produced.
When addition of an additional component is performed by a dry mixing method, a firing process may be performed after performing the above-described drying process on the obtained mixture as necessary.
Prior to the firing step, a mixture of the solid recovery component and the additional component or a dried product thereof may be granulated. Examples of the sizing method include a method in which a mixture or a dried product is pressure-molded and then crushed, further sieved, and only granules classified into a specific range are employed. In addition, in this case, for example, the obtained dried product is molded into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and a length of 5 mm by a tableting molding machine. And the catalyst for methacrylic acid manufacture can be obtained by baking this molded article for 12 hours at 380 degreeC under air circulation.

こうして得られたメタクリル酸製造用ヘテロポリ酸系触媒は、使用済み触媒のうち、活性が低く不要成分であると考えられていた難溶性ヘテロポリ酸塩を原料としているにもかかわらず、未使用触媒の収率と比較した収率、すなわち再生率が９０％以上の良好な性能を発揮する。
また、以上説明した製造方法は、使用済み触媒を水性媒体と接触させ、得られた分散液を液体成分と固体回収成分とに固液分離する分離工程と、固体回収成分を原料としてメタクリル酸製造用ヘテロポリ酸系触媒を調製する触媒調製工程とを有する簡単かつ低コストな方法である。 The heteropolyacid catalyst for methacrylic acid production obtained in this way is an unused catalyst in spite of using a hardly soluble heteropolyacid salt that was considered to be an unnecessary component because of its low activity among used catalysts. It exhibits good performance with a yield of 90% or more compared to the yield, that is, the regeneration rate.
In addition, the production method described above includes a separation step in which a used catalyst is brought into contact with an aqueous medium, and the resulting dispersion is separated into a liquid component and a solid recovery component, and methacrylic acid is produced using the solid recovery component as a raw material. And a catalyst preparation step for preparing a heteropolyacid catalyst for use.

このように使用済み触媒中の難溶性ヘテロポリ酸塩を原料とすることで、未使用触媒のメタクリル酸収率に対して９０％以上の収率のヘテロポリ酸系触媒が得られる理由については、難溶性ヘテロポリ酸塩が、Ｈ−ヘテロポリ酸よりも耐熱性に優れていることに起因すると考えられる。
すなわち、ヘテロポリ酸系触媒をメタクリル酸の製造に使用した場合、熱や還元雰囲気などにより、Ｈ−ヘテロポリ酸が分解して触媒性能低下を引き起こすが、難溶性ヘテロポリ酸はほとんど分解せず、未使用時の状態を維持していると推測できる。よって、このような良好な状態を維持している難溶性ヘテロポリ酸を回収し、これを原料とすることで、未使用のものと同程度の性能のヘテロポリ酸系触媒が得られると考えられる。
このように難溶性ヘテロポリ酸塩が未使用時の状態を維持し、Ｈ−ヘテロポリ酸が主に分解されているという推測は、難溶性ヘテロポリ酸の元素分析組成が、使用前後で変わらないこと及び、使用済み触媒中の水溶性成分（すなわち、主にＨ−ヘテロポリ酸）のヘテロポリ酸が一部分解していたことから裏付けられる。
また、このような方法では、分離工程において、メタクリル酸製造時の熱や還元雰囲気などにより生成した分解生成物は水溶性成分として固体回収成分から分離され、製造されたヘテロポリ酸系触媒中にこれら分解生成物がほとんど混入しない。この点も、優れた性能のヘテロポリ酸系触媒が得られる理由の１つと考えられる。 The reason why a heteropolyacid catalyst having a yield of 90% or more with respect to the methacrylic acid yield of the unused catalyst can be obtained by using the hardly soluble heteropolyacid salt in the used catalyst as a raw material is difficult. It is considered that the soluble heteropolyacid salt is more excellent in heat resistance than H-heteropolyacid.
That is, when a heteropolyacid-based catalyst is used for the production of methacrylic acid, H-heteropolyacid is decomposed due to heat, a reducing atmosphere, etc. to cause a decrease in catalyst performance, but hardly soluble heteropolyacid is hardly decomposed and unused. It can be inferred that the state of time is maintained. Therefore, it is considered that a heteropolyacid catalyst having the same performance as that of an unused one can be obtained by collecting the hardly soluble heteropolyacid maintaining such a good state and using it as a raw material.
In this way, it is assumed that the hardly soluble heteropolyacid salt maintains the state when it is not used, and that the H-heteropolyacid is mainly decomposed, that the elemental analysis composition of the hardly soluble heteropolyacid is not changed before and after use. This is supported by the partial decomposition of the heteropolyacid of the water-soluble component (that is, mainly H-heteropolyacid) in the spent catalyst.
In such a method, in the separation step, decomposition products generated by heat, reducing atmosphere, etc. during the production of methacrylic acid are separated from solid recovery components as water-soluble components, and these are contained in the produced heteropolyacid catalyst. Almost no decomposition products are mixed. This point is also considered to be one of the reasons why a heteropolyacid catalyst having excellent performance can be obtained.

以下、本発明について、実施例を用いて説明する。
実施例において、「部」は質量部であり、含有元素の定量分析はＩＣＰ発光分析法、原子吸光分析法より行った。ヘテロポリ酸塩の生成の確認はＸ線回折により行った。
また、メタクリル酸の製造における原料ガスと生成物の定量分析はガスクロマトグラフィーにより行った。
なお、メタクロレインの反応率、生成するメタクリル酸の選択率および単流収率は以下のように定義される。
メタクロレインの反応率（％）＝（Ｂ／Ａ）×１００
メタクリル酸の選択率（％）＝（Ｃ／Ｂ）×１００
メタクリル酸の単流収率（％）＝（Ｃ／Ａ）×１００
（ここで、Ａは供給したメタクロレインのモル数、Ｂは反応したメタクロレインのモル数、Ｃは生成したメタクリル酸のモル数である。） Hereinafter, the present invention will be described using examples.
In the examples, “part” is part by mass, and quantitative analysis of the contained elements was performed by ICP emission spectrometry and atomic absorption spectrometry. Confirmation of the formation of the heteropolyacid salt was performed by X-ray diffraction.
The quantitative analysis of the raw material gas and the product in the production of methacrylic acid was performed by gas chromatography.
In addition, the reaction rate of methacrolein, the selectivity of the methacrylic acid to produce | generate, and a single flow yield are defined as follows.
Reaction rate of methacrolein (%) = (B / A) × 100
Methacrylic acid selectivity (%) = (C / B) × 100
Single stream yield of methacrylic acid (%) = (C / A) × 100
(Here, A is the number of moles of methacrolein supplied, B is the number of moles of reacted methacrolein, and C is the number of moles of methacrylic acid produced.)

［参考例１］
酸化モリブデン５０００部、メタバナジン酸１３５部、８５質量％リン酸１０００部を水１００００部に分散させ、昇温しながら、６０質量％ヒ酸６８０部、硝酸セシウム５００部、２８質量％アンモニア水１８００部、硝酸ジルコニウム４２部、硝酸銅７０部、硝酸鉄６０部のそれぞれを加えて、加熱攪拌しながら蒸発乾固した。
得られた固形物を１３０℃で１６時間乾燥したものを加圧成型後破砕し、篩の目開き０．８５ｍｍ篩い上と１．７０ｍｍ篩い下の範囲のものを分取して、空気流通下にこれを３８０℃で５時間焼成してヘテロポリ酸系触媒（未使用触媒１）を得た。
この未使用触媒１の金属成分の組成はＰ１Ａｓ１Ｍｏ１２Ｖ０.３Ｃｕ０．１Ｆｅ０．１Ｚｒ０．０５Ｃｓ１．３であった。
この未使用触媒１を充填した反応管に、メタクロレイン５容量％、酸素１０容量％、水蒸気３０容量％、窒素５５容量％の混合ガスを反応温度２７０℃、接触時間３．６秒の反応条件で通じ、メタクロレインの気相接触酸化反応によるメタクリル酸の製造を行った。
初期のメタクロレイン反応率は７１．１％、メタクリル酸選択率は８７．２％、メタクリル酸単流収率は６２．１％であった。 [Reference Example 1]
5,000 parts of molybdenum oxide, 135 parts of metavanadate, 1000 parts of 85% by weight phosphoric acid are dispersed in 10,000 parts of water, and while raising the temperature, 680 parts of 60% by weight arsenic acid, 500 parts of cesium nitrate, 1800 parts of 28% by weight aqueous ammonia Then, 42 parts of zirconium nitrate, 70 parts of copper nitrate and 60 parts of iron nitrate were added and evaporated to dryness while heating and stirring.
The solid material obtained was dried at 130 ° C. for 16 hours and then crushed after pressure molding. The sieve was separated in a range of 0.85 mm sieve top and 1.70 mm sieve under air flow. This was calcined at 380 ° C. for 5 hours to obtain a heteropolyacid catalyst (unused catalyst 1).
The composition of the metal component of the unused catalyst 1 was P 1 As 1 Mo 12 V 0.3 Cu 0.1 Fe 0.1 Zr 0.05 Cs 1.3.
A reaction tube filled with this unused catalyst 1 was mixed with 5% by volume of methacrolein, 10% by volume of oxygen, 30% by volume of water vapor, and 55% by volume of nitrogen. The reaction conditions were a reaction temperature of 270 ° C. and a contact time of 3.6 seconds. Then, methacrylic acid was produced by a gas phase catalytic oxidation reaction of methacrolein.
The initial methacrolein reaction rate was 71.1%, the methacrylic acid selectivity was 87.2%, and the methacrylic acid single stream yield was 62.1%.

［実施例１］
未使用触媒１を用いて参考例１の反応条件で３１００時間反応を続けた後、使用済み触媒を抜き出した。これを使用済み触媒１とする。
ついで、この使用済み触媒１の５０部を、水道水をイオン交換処理したｐＨ５．５の水１０００部に分散させて分散液を得た後、この分散液を日立工機株式会社製高速冷凍遠心分離機ＣＲ２２Ｆによる遠心分離（１６，０００ｒｐｍ×５分間）（以下遠心分離という。）をして、液体成分と固体回収成分とに固液分離した。
得られた固体回収成分を６０℃で８時間真空乾燥させた。
この固体回収成分は、元素分析とＸ線回折によればセシウムのヘテロポリ酸塩であり、金属成分の元素組成はＰ０．５Ａｓ０．５Ｍｏ１２Ｖ０．３Ｃｕ０．１Ｆｅ０．１Ｚｒ０．０２Ｃｓ２（＝Ｐ０．３２５Ａｓ０．３２５Ｍｏ７．８Ｖ０．１９５Ｃｕ０．０６５Ｆｅ０．０６Ｚｒ０．０１３Ｃｓ１．３）であった。
この固体回収成分の元素組成と未使用触媒１の上記元素組成とを比較し、セシウム以外の各元素成分を追加成分として追加することで、未使用触媒１と同じ組成の再生触媒１を製造した。
具体的には次のように行った。
酸化モリブデン１７部、メタバナジン酸０．３部、８５質量％リン酸２部を水５０部に分散させ、昇温しながら、６０質量％ヒ酸６部、２８質量％アンモニア水１５部、硝酸ジルコニウム０．２２部、硝酸銅０．２４部、硝酸鉄０．４５部のそれぞれを加えて、加熱攪拌し、ヘテロポリ酸塩の液状物を得た。
この液状物と回収された固体回収成分とを混合したものを蒸発乾固し、得られた固形物を１３０℃で１６時間乾燥した。ついで、この乾燥品を加圧成型して破砕し、篩の目開き０．８５ｍｍ篩い上と１．７０ｍｍ篩い下の範囲のものを分取して、空気流通下にこれを３８０℃で５時間焼成した。
こうして得られたヘテロポリ酸系触媒の金属成分の組成を確認したところ、Ｐ１Ａｓ１Ｍｏ１２Ｖ０．３Ｃｕ０．１Ｆｅ０．１Ｚｒ０．０５Ｃｓ１．３であった。 [Example 1]
After the reaction was continued for 3100 hours under the reaction conditions of Reference Example 1 using the unused catalyst 1, the used catalyst was extracted. This is used catalyst 1.
Next, 50 parts of the used catalyst 1 was dispersed in 1000 parts of pH 5.5 water obtained by ion exchange treatment of tap water to obtain a dispersion, and this dispersion was then subjected to a high-speed refrigeration centrifuge manufactured by Hitachi Koki Co., Ltd. Centrifugation (16,000 rpm × 5 minutes) with a separator CR22F (hereinafter referred to as “centrifugation”) was performed to separate the liquid component from the solid recovery component.
The obtained solid recovery component was vacuum-dried at 60 ° C. for 8 hours.
This solid recovery component is a cesium heteropolyacid salt according to elemental analysis and X-ray diffraction, and the elemental composition of the metal component is P 0.5 As 0.5 Mo 12 V 0.3 Cu 0.1 Fe 0. 1 Zr 0.02 Cs 2 (= P 0.325 As 0.325 Mo 7.8 V 0.195 Cu 0.065 Fe 0.06 Zr 0.013 Cs 1.3 ).
The regenerated catalyst 1 having the same composition as that of the unused catalyst 1 was produced by comparing the element composition of the solid recovery component with the above element composition of the unused catalyst 1 and adding each element component other than cesium as an additional component. .
Specifically, it was performed as follows.
17 parts of molybdenum oxide, 0.3 parts of metavanadate, 2 parts of 85% by weight phosphoric acid are dispersed in 50 parts of water, and while raising the temperature, 6 parts of 60% by weight arsenic acid, 15 parts of 28% by weight ammonia water, zirconium nitrate 0.22 parts, 0.24 parts of copper nitrate, and 0.45 parts of iron nitrate were added, and the mixture was heated and stirred to obtain a heteropoly acid salt liquid.
A mixture of this liquid and the recovered solid recovery component was evaporated to dryness, and the obtained solid was dried at 130 ° C. for 16 hours. Next, the dried product is pressure-molded and crushed, and the dried product is separated in a range between a sieve opening of 0.85 mm and a sieve under a 1.70 mm sieve, and this is allowed to flow at 380 ° C. for 5 hours under air flow. Baked.
When the composition of the metal component of the heteropolyacid catalyst thus obtained was confirmed, it was P 1 As 1 Mo 12 V 0.3 Cu 0.1 Fe 0.1 Zr 0.05 Cs 1.3 .

この触媒（再生触媒１）を用いて、参考例１と同じ反応条件でメタクロレインの気相接触酸化反応によるメタクリル酸の製造を行った結果、初期のメタクロレイン反応率は６５．３％、メタクリル酸選択率は８９．２％、メタクリル酸単流収率５８．３％であり、未使用触媒１の収率と比較した再生率は９４％となり、良好な性能が発揮された。   Using this catalyst (regenerated catalyst 1), methacrylic acid was produced by gas phase catalytic oxidation of methacrolein under the same reaction conditions as in Reference Example 1. As a result, the initial methacrolein reaction rate was 65.3%, The acid selectivity was 89.2%, the methacrylic acid single stream yield was 58.3%, and the regeneration rate compared with the yield of the unused catalyst 1 was 94%, and good performance was exhibited.

［参考例２］
酸化モリブデン５０００部、メタバナジン酸１３５部、８５質量％リン酸１０００部を水１００００部に分散させ、昇温しながら、硝酸セシウム５００部、２８質量％アンモニア水１８００部、硝酸ジルコニウム４２部、硝酸銅７０部、硝酸鉄６０部のそれぞれを加えて、加熱攪拌しながら蒸発乾固した。
得られた固形物を１３０℃で１６時間乾燥したものを加圧成型後破砕し、篩の目開き０．８５ｍｍ篩い上と１．７０ｍｍ篩い下の範囲のものを分取して、空気流通下にこれを３８０℃で５時間焼成してヘテロポリ酸系触媒（未使用触媒２）を得た。
この未使用触媒２の金属成分の組成はＰ１Ｍｏ１２Ｖ０.３Ｃｕ０．１Ｆｅ０．１Ｚｒ０．０５Ｃｓ１．３であった。
この未使用触媒２を用いて参考例１と同様の反応条件でメタクロレインの気相接触酸化反応によるメタクリル酸の製造を行った。
初期のメタクロレイン反応率は６８．４％、メタクリル酸選択率は８７．６％、メタクリル酸単流収率は５９．９％であった。 [Reference Example 2]
5000 parts of molybdenum oxide, 135 parts of metavanadate, 1000 parts of 85% by weight phosphoric acid are dispersed in 10,000 parts of water, and while raising the temperature, 500 parts of cesium nitrate, 1800 parts of 28% by weight aqueous ammonia, 42 parts of zirconium nitrate, copper nitrate 70 parts and 60 parts of iron nitrate were added and evaporated to dryness while stirring with heating.
The solid material obtained was dried at 130 ° C. for 16 hours and then crushed after pressure molding. The sieve was separated in a range of 0.85 mm sieve top and 1.70 mm sieve under air flow. This was calcined at 380 ° C. for 5 hours to obtain a heteropolyacid catalyst (unused catalyst 2).
The composition of the metal component of the unused catalyst 2 was P 1 Mo 12 V 0.3 Cu 0.1 Fe 0.1 Zr 0.05 Cs 1.3 .
Using this unused catalyst 2, methacrylic acid was produced by a gas phase catalytic oxidation reaction of methacrolein under the same reaction conditions as in Reference Example 1.
The initial methacrolein reaction rate was 68.4%, the methacrylic acid selectivity was 87.6%, and the methacrylic acid single stream yield was 59.9%.

［実施例２］
未使用触媒２を用いて参考例２の反応条件で３０００時間反応を続けた後、使用済み触媒を抜き出した。これを使用済み触媒２とする。
ついで、この使用済み触媒２の５０部を、水道水をイオン交換処理したｐＨ５．５の水１０００部に分散させて分散液を得た後、この分散液を遠心分離して、液体成分と固体回収成分とに固液分離した。
得られた固体回収成分を６０℃で８時間真空乾燥させた。
この固体回収成分は、元素分析とＸ線回折によればセシウムのヘテロポリ酸塩であり、金属成分の元素組成はＰ１Ｍｏ１２Ｖ０．３Ｃｕ０．１Ｆｅ０．１Ｚｒ０．０２Ｃｓ２（＝Ｐ０．６５Ｍｏ７．８Ｖ０．１９５Ｃｕ０．０６５Ｆｅ０．０６５Ｚｒ０．０１３Ｃｓ１．３）であった。
この固体回収成分の元素組成と未使用触媒２の上記元素組成とを比較し、セシウム以外の各元素成分を追加成分として追加することで、未使用触媒２と同じ組成の再生触媒２を製造した。
具体的には次のように行った。
酸化モリブデン１７部、メタバナジン酸０．３４部、８５質量％リン酸１部を水５０部に分散させ、昇温しながら、２８質量％アンモニア水１５部、硝酸ジルコニウム０．２２部、硝酸銅０．２４部、硝酸鉄０．３９部のそれぞれを加えて、加熱攪拌し、ヘテロポリ酸塩の液状物を得た。
この液状物と回収された固体回収成分とを混合したものを蒸発乾固し、得られた固形物を１３０℃で１６時間乾燥した。ついで、この乾燥品を加圧成型して破砕し、篩の目開き０．８５ｍｍ篩い上と１．７０ｍｍ篩い下の範囲のものを分取して、空気流通下にこれを３８０℃で５時間焼成した。
こうして得られたヘテロポリ酸系触媒の金属成分の組成を確認したところ、Ｐ１Ｍｏ１２Ｖ０．３Ｃｕ０．１Ｆｅ０．１Ｚｒ０．０５Ｃｓ１．３であった。 [Example 2]
The reaction was continued for 3000 hours under the reaction conditions of Reference Example 2 using the unused catalyst 2, and then the used catalyst was extracted. This is used catalyst 2.
Next, 50 parts of the used catalyst 2 was dispersed in 1000 parts of water having a pH of 5.5 obtained by ion-exchange treatment of tap water to obtain a dispersion, and the dispersion was centrifuged to obtain a liquid component and a solid. Solid-liquid separation into recovered components.
The obtained solid recovery component was vacuum-dried at 60 ° C. for 8 hours.
This solid recovery component is a cesium heteropolyacid salt according to elemental analysis and X-ray diffraction, and the elemental composition of the metal component is P 1 Mo 12 V 0.3 Cu 0.1 Fe 0.1 Zr 0.02 Cs. 2 (= P 0.65 Mo 7.8 V 0.195 Cu 0.065 Fe 0.065 Zr 0.013 Cs 1.3 ).
The elemental composition of the solid recovery component was compared with the above elemental composition of the unused catalyst 2, and each element component other than cesium was added as an additional component, thereby producing a regenerated catalyst 2 having the same composition as the unused catalyst 2. .
Specifically, it was performed as follows.
17 parts of molybdenum oxide, 0.34 part of metavanadic acid, 1 part of 85% by weight phosphoric acid are dispersed in 50 parts of water, and while raising the temperature, 15 parts of 28% by weight aqueous ammonia, 0.22 part of zirconium nitrate, 0 parts of copper nitrate .24 parts and 0.39 parts of iron nitrate were added, and heated and stirred to obtain a heteropolyacid salt liquid.
A mixture of this liquid and the recovered solid recovery component was evaporated to dryness, and the obtained solid was dried at 130 ° C. for 16 hours. Next, the dried product is pressure-molded and crushed, and the dried product is separated in a range between a sieve opening of 0.85 mm and a sieve under a 1.70 mm sieve, and this is allowed to flow at 380 ° C. for 5 hours under air flow. Baked.
Thus where the obtained confirmed the composition of the metal component of the heteropolyacid catalyst was P 1 Mo 12 V 0.3 Cu 0.1 Fe 0.1 Zr 0.05 Cs 1.3.

この触媒（再生触媒２）を用いて、参考例２と同じ反応条件でメタクロレインの気相接触酸化反応によるメタクリル酸の製造を行った結果、初期のメタクロレイン反応率は６２．１％、メタクリル酸選択率は８８．５％、メタクリル酸単流収率５４．９％であり、未使用触媒２の収率に比較した再生率は９２％となり、良好な性能が発揮された。   Using this catalyst (regenerated catalyst 2), methacrylic acid was produced by vapor phase catalytic oxidation of methacrolein under the same reaction conditions as in Reference Example 2. As a result, the initial methacrolein reaction rate was 62.1%, The acid selectivity was 88.5%, the methacrylic acid single stream yield was 54.9%, and the regeneration rate compared to the yield of the unused catalyst 2 was 92%, and good performance was exhibited.

Figure 2008000709
Figure 2008000709

Claims (1)

気相接触酸化によるメタクリル酸の製造に使用されるヘテロポリ酸系触媒の製造方法において、
セシウム、カリウム、タリウム、ルビジウムからなる群より選ばれる１種以上の元素とモリブデンを含有し、気相接触酸化によるメタクリル酸の製造に使用された使用済みヘテロポリ酸系触媒をｐＨ１以上、ｐＨ８未満の水性媒体と接触させ、得られた分散液を液体成分と固体回収成分とに固液分離する分離工程と、前記固体回収成分を原料として、メタクリル酸製造用ヘテロポリ酸系触媒を調製する触媒調製工程とを有することを特徴とするヘテロポリ酸系触媒の製造方法。

In the method for producing a heteropolyacid catalyst used for the production of methacrylic acid by gas phase catalytic oxidation,
A used heteropolyacid catalyst containing at least one element selected from the group consisting of cesium, potassium, thallium, and rubidium and molybdenum, and used in the production of methacrylic acid by gas phase catalytic oxidation is at least pH 1 and less than pH 8 A separation step in which the obtained dispersion is brought into contact with an aqueous medium and subjected to solid-liquid separation into a liquid component and a solid recovery component, and a catalyst preparation step for preparing a heteropolyacid catalyst for methacrylic acid production using the solid recovery component as a raw material A process for producing a heteropolyacid catalyst, comprising:

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