JP3690939B2 - Catalyst for synthesizing methacrylic acid and method for producing methacrylic acid - Google Patents
Catalyst for synthesizing methacrylic acid and method for producing methacrylic acid Download PDFInfo
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- JP3690939B2 JP3690939B2 JP16016499A JP16016499A JP3690939B2 JP 3690939 B2 JP3690939 B2 JP 3690939B2 JP 16016499 A JP16016499 A JP 16016499A JP 16016499 A JP16016499 A JP 16016499A JP 3690939 B2 JP3690939 B2 JP 3690939B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Description
【０００１】
【発明の属する技術分野】
本発明は、少なくともモリブデンを含有するメタクリル酸合成用触媒およびメタクリル酸の製造方法に関する。
【０００２】
【従来の技術】
少なくともモリブデンを含有する触媒を用いるメタクリル酸の合成方法の原料としては、メタクロレイン、イソブチルアルデヒド等が用いられる。一般に、このような原料を用いるメタクリル酸合成反応は、固定床反応器を用いて高温の気相下で行われる。固定床反応器を用いる場合、通常、触媒はある程度以上の大きさに成形されたものである。
【０００３】
メタクロレインからメタクリル酸を合成するために用いられる触媒の製造方法、特に成形方法に関しては数多くの提案がなされている。例えば、特開昭５５−７３３４７号公報には、触媒粉にセルロース類等を混合して成形する方法、特開昭６０−１５０８３４号公報には、触媒粉にグラファイトを混合して押出成形する方法、特開平８−１０６２１号公報には、触媒粉を１〜２５０μｍに調整して成形する方法が記載されている。
【０００４】
【発明が解決しようとする課題】
しかし、これらの方法で得られた触媒は、触媒活性およびメタクリル酸の選択性が工業触媒としてはまだ不十分であり、更に改良が望まれている。
【０００５】
したがって、本発明の目的は、触媒活性およびメタクリル酸の選択性に優れたメタクリル酸合成用触媒およびその触媒を用いるメタクリル酸の製造方法を提供することにある。
【０００６】
【課題を解決するための手段】
本発明は、少なくともモリブデンを含有する混合溶液または水性スラリーの粉状の乾燥物を一次成形した一次成形品を粉砕し、得られた一次成形品の粉砕物を二次成形した二次成形品を３００〜５００℃の温度で焼成して製造されたメタクリル酸合成用触媒である。また、本発明は上記のメタクリル酸合成用触媒を用いることを特徴とするメタクリル酸の製造方法である。
【０００７】
【発明の実施の形態】
本発明のメタクリル酸合成用触媒は、モリブデンを必須成分として含有する複合酸化物触媒であれば特に限定されないが、好ましくは下記の式（１）、
ＭｏaＰbＣｕcＶdＸeＹfＯg （１）
（式中、Ｍｏ、Ｐ、Ｃｕ、ＶおよびＯはそれぞれモリブデン、リン、銅、バナジウムおよび酸素を表し、Ｘは鉄、コバルト、ニッケル、亜鉛、マグネシウム、カルシウム、ストロンチウム、バリウム、チタン、クロム、タングステン、マンガン、銀、ホウ素、ケイ素、スズ、鉛、ヒ素、アンチモン、ビスマス、ニオブ、タンタル、ジルコニウム、インジウム、イオウ、セレン、テルル、ランタンおよびセリウムからなる群より選ばれた少なくとも１種の元素、Ｙはカリウム、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種の元素を表す。ただし、ａ、ｂ、ｃ、ｄ、ｅ、ｆおよびｇは各元素の原子比を表し、ａ＝１２のとき、０．１≦ｂ≦３、０．０１≦ｃ≦３、０．０１≦ｄ≦３、０≦ｅ≦３、０．０１≦ｆ≦３であり、ｇは前記各元素の原子価を満足するのに必要な酸素の原子比である。）
で表される組成を有するものである。
【０００８】
メタクリル酸合成用触媒の製造において、一次成形の原料として用いる粉状の乾燥物を製造する方法は、少なくともモリブデンを含有する混合溶液または水性スラリーを経由し、成分の著しい偏在を伴わない限り特に限定されず、例えば、従来から知られている共沈法、蒸発乾固法、および酸化物混合法等の種々の方法を用いることができる。
【０００９】
少なくともモリブデンを含有する混合溶液または水性スラリー（以下、触媒原料液という。）の調製に用いる触媒原料は特に限定されず、各元素の硝酸塩、炭酸塩、酢酸塩、アンモニウム塩、酸化物、ハロゲン化物等を組み合わせて使用することができる。例えば、モリブデン原料としてはパラモリブデン酸アンモニウム、三酸化モリブデン、モリブデン酸、塩化モリブデン等が使用できる。
【００１０】
本発明において、触媒原料液を乾燥する方法は特に限定されず、箱型乾燥機、噴霧乾燥機、ドラムドライヤー、スラリードライヤー等を用いることができる。なお、本発明において乾燥とは、触媒原料液から水分を減じて実質的に固体状にすることであり、乾燥して得られる乾燥物の含水率は特に限定されない。また、乾燥直後の乾燥物の形状は特に限定されず、例えば、粉状、ブロック状等が挙げられる。
【００１１】
本発明では、粉状の乾燥物を一次成形する必要があるので、乾燥物が粉状でなかったり、粉状であっても大きさが適切でない場合は、乾燥物を適宜粉砕する等して粉状にする。粉状にする方法は特に限定されず、通常は各種の粉砕機を用いた一般の粉砕方法が適用される。また、粉状の乾燥物の大きさは、後述する一次成形に支障がない限り特に限定されないが、呼び寸法１ｍｍのふるいを通過できない大きさのものが存在しないことが好ましい。なお、ここで呼び寸法とは、ふるいの網の目の一辺の長さを指す。
【００１２】
このようにして得られた粉状の乾燥物（以下、乾燥粉という。）を一次成形する方法は、粉状物から成形品を得る方法であれば特に限定されず、例えば、打錠成形、押出成形、造粒等の各種の成形法を適用することができる。また、成形の際には、成形品の比表面積、細孔容積および細孔分布を再現性よく制御したり、機械的強度を高める等の目的で、例えば、硫酸バリウム、硝酸アンモニウム等の無機塩類、グラファイト等の滑剤、セルロース類、でんぷん、ポリビニルアルコール、ステアリン酸等の有機物、シリカゾル、アルミナゾル等の水酸化物ゾル、ウィスカー、ガラス繊維、炭素繊維等の無機質繊維等の従来公知の添加剤を、乾燥粉に対して適宜添加してもよい。なお、一次成形して得られた一次成形品の形状は特に限定されず、例えば、球状、円柱状、リング状（円筒状）、板状等の任意の形状が挙げられる。一次成形品の大きさは特に限定されないが、呼び寸法２ｍｍのふるいを通過できない大きさが好ましい。
【００１３】
本発明において、一次成形品を粉砕する方法は特に限定されないが、通常は各種の粉砕機を用いた一般の粉砕方法が適用される。一次成形品の粉砕物（以下、一次成形粉という。）の大きさは、後述する二次成形に支障がない限り特に限定されないが、呼び寸法２ｍｍのふるいを通過できない大きさのものが存在しない大きさが好ましい。
【００１４】
本発明では、少なくとも一次成形粉を含んだものを二次成形することが重要であり、一次成形粉に乾燥粉を混合したものを二次成形することが好ましい。
【００１５】
二次成形される一次成形粉や一次成形粉と乾燥粉を混合したもの等の少なくとも一次成形粉を含んだものには、呼び寸法１ｍｍのふるいを通過できない大きさの一次成形粉が５質量％以上含まれていることが好ましく、特に１０質量％以上含まれていることが好ましい。
【００１６】
一次成形粉を二次成形することで、最終的な触媒中に好ましい細孔構造が発現し、触媒活性およびメタクリル酸の選択性に優れた触媒が得られる。なお、一次成形粉に乾燥粉を混合したものを二次成形する場合、この混合物中における一次成形粉の割合は１０質量％以上が好ましく、２０質量％以上であることが特に好ましい。
【００１７】
二次成形する方法は特に限定されず、一次成形と同様に各種成形法を適用することができるが、一次成形の方法と同じ成形方法が好ましい。また、一次成形の場合と同様に添加剤を混合して成形してもよい。二次成形して得られる二次成形品の形状は特に限定されないが、一次成形と同じ形状が好ましい。
【００１８】
得られた二次成形品を３００〜５００℃の温度で焼成することにより、本発明のメタクリル酸合成用触媒が得られる。焼成の時間は特に限定されないが、短すぎると良好な触媒が得られないため、１時間以上が好ましい。
【００１９】
このようにして得られた触媒を用いて、メタクリル酸を製造するときの反応条件は、用いる反応原料や反応方式等により異なるので一概に言えないが、従来から知られている反応条件がそのまま適用できる。用いられる反応原料としては、メタクロレインおよびイソブチルアルデヒド等が挙げられる。
【００２０】
例えば、本発明のメタクリル酸合成用触媒を固定床反応器に充填してメタクロレインを分子状酸素により気相接触酸化してメタクリル酸を製造する場合の反応条件は次の通りである。原料ガス中のメタクロレインの濃度は通常１〜２０容量％であり、３〜１０容量％が好ましい。原料ガスには低級飽和アルデヒド等の実質的に反応に影響を与えない不純物を少量含んでいてもよい。分子状酸素源としては、空気を用いるのが工業的には有利であるが、必要に応じて純酸素で富化した空気も使用できる。原料ガス中の酸素の量は、メタクロレイン１モルに対して０．５〜３モルが好ましい。また、原料ガスは不活性ガス、水蒸気等で希釈して用いることが好ましい。反応圧力は常圧ないし数気圧である。反応温度は２００〜４５０℃が好ましい。
【００２１】
【実施例】
以下、本発明を実施例および比較例を挙げて詳細に説明するが、本発明はこれらの実施例に限定されるものではない。実施例および比較例中の「部」は重量部を意味する。反応生成物等の分析はガスクロマトグラフィーを用いて行った。また、メタクロレインの反応率、生成したメタクリル酸の選択率および収率は次式により算出した。
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を表す。
【００２２】
［実施例１］
パラモリブデン酸アンモニウム１００部、メタバナジン酸アンモニウム４．４部および硝酸カリウム４．８部を純水４００部に溶解した。これを攪拌しながら、８５質量％リン酸水溶液８．２部を純水１０部に溶解した溶液を加え、更に硝酸銅１．１部を純水１０部に溶解した溶液を加えた。次に硝酸ビスマス６．９部に６０質量％硝酸水溶液７．０部および純水４０部を加え、得られた硝酸ビスマスの均一溶液を前記混合液に加えた後、９５℃に昇温した。これに６０質量％ヒ酸水溶液２．２部を純水１０部に溶解した溶液を加え、続いて三酸化アンチモン２．１部および二酸化セリウム１．６部を加えた。得られた触媒原料液を加熱攪拌しながら蒸発乾固した後、さらに１３０℃で１６時間乾燥して、ブロック状の乾燥物を得た。
【００２３】
この触媒原料液の乾燥物を呼び寸法１ｍｍのふるいを通過できない大きさのものが存在しないように、ドラッグミルを用いて粉砕した。このようにして得られた乾燥粉の一部を二次成形に使用するために取り置き、残りの乾燥粉１００部に対してグラファイト２部を添加した後、打錠成形機により、外径５ｍｍ、内径２ｍｍ、長さ５ｍｍのリング状に一次成形した。得られた一次成形品を呼び寸法２ｍｍのふるいを通過できない大きさのものが存在しないように、ジョークラッシャーを用いて粉砕した。このようにして得られた一次成形粉４０部と取り置きしておいた乾燥粉６０部を混合して二次成形用の混合物を得た。この混合物中の、呼び寸法１ｍｍのふるいを通過できない一次成形粉の割合は２１質量％であった。
【００２４】
この混合物１００部に対してグラファイト１部を添加した後、打錠成形機により、外径５ｍｍ、内径２ｍｍ、長さ５ｍｍのリング状に二次成形して二次成形品とした。二次成形品を空気流通下に３８０℃で５時間焼成してメタクリル酸合成用触媒を得た。この触媒の酸素以外の元素の組成は、Ｍｏ12Ｐ1.5Ｖ0.8Ｃｕ0.1Ｓｂ0.3Ｂｉ0.3Ａｓ0.2Ｃｅ0.2Ｋ1であった。
【００２５】
この触媒を固定床反応管に充填し、メタクロレイン５容量％、酸素１０容量％、水蒸気３０容量％および窒素５５容量％からなる原料ガスを反応温度２９０℃、接触時間３．６秒で通じてメタクリル酸を製造したところ、メタクロレイン反応率９１．４％、メタクリル酸選択率８８．６％、メタクリル酸収率８１．０％であった。
【００２６】
［実施例２］
実施例１において、一次成形粉３部と乾燥粉９７部を混合して二次成形用の混合物とした以外は実施例１と同様に実施した結果、メタクロレイン反応率９０．２％、メタクリル酸選択率８８．３％、メタクリル酸収率７９．６％であった。なお、このとき二次成形用の混合物中の、呼び寸法１ｍｍのふるいを通過できない一次成形粉の割合は２質量％であった。
【００２７】
［比較例１］
二次成形を行わず、一次成形品を焼成した以外は実施例１と同様に実施した結果、メタクロレイン反応率９０．０％、メタクリル酸選択率８８．２％、メタクリル酸収率７９．４％であった。
【００２８】
［比較例２］
触媒原料液の乾燥物を呼び寸法２ｍｍのふるいを通過できない大きさのものが存在しないよう粉砕して乾燥粉を得た以外は比較例１と同様に実施した結果、メタクロレイン反応率８９．８％、メタクリル酸選択率８８．１％、メタクリル酸収率７９．１％であった。
【００２９】
［実施例３］
パラモリブデン酸アンモニウム１００部、メタバナジン酸アンモニウム２．８部および硝酸セシウム９．２部を純水４００部に溶解した。これを攪拌しながら、８５質量％リン酸水溶液８．２部を純水１０部に溶解した溶液およびテルル酸１．１部を純水１０部に溶解した溶液を加え、攪拌しながら９５℃に昇温した。次いで硝酸銅３．４部、硝酸第二鉄７．６部、硝酸亜鉛１．４部および硝酸マグネシウム１．８部を純水８０部に溶解した溶液を加えた。更にこの混合液を１００℃で３０分間攪拌して触媒原料液を得た。
【００３０】
この触媒原料液を、並流式噴霧乾燥機を用いて、乾燥機入口温度３００℃、スラリー噴霧用回転盤の回転速度２００００回転／分の条件で乾燥した。このようにして得られた乾燥粉の粒子径は１〜２００μｍの範囲であった。この乾燥粉の一部を二次成形に使用するために取り置き、残りの乾燥粉１００部に対してガラス繊維３部を添加した後、打錠成形機により、外径５ｍｍ、内径２ｍｍ、長さ３ｍｍのリング状に一次成形した。このようにして得られた一次成形品を呼び寸法２ｍｍのふるいを通過できない大きさのものが存在しないように、ドラッグミルを用いて粉砕した。このようにして得られた一次成形粉６０部と取り置きしておいた乾燥粉４０部を混合して二次成形用の混合物を得た。この混合物中の、呼び寸法１ｍｍのふるいを通過できない一次成形粉の割合は３３質量％であった。
【００３１】
この混合物を打錠成形機により、外径５ｍｍ、内径２ｍｍ、長さ３ｍｍのリング状に二次成形して二次成形品とした。二次成形品を空気流通下に３８０℃で５時間焼成してメタクリル酸合成用触媒を得た。この触媒の酸素以外の元素の組成は、Ｍｏ12Ｐ1.5Ｖ0.5Ｃｕ0.3Ｆｅ0.4Ｔｅ0.1Ｍｇ0.15Ｚｎ0.1Ｃｓ1であった。
【００３２】
この触媒を固定床反応管に充填し、実施例１と同じ反応条件でメタクリル酸を製造したところ、メタクロレイン反応率８８．７％、メタクリル酸選択率８６．１％、メタクリル酸収率７６．４％であった。
【００３３】
［比較例３］
二次成形を行わず、一次成形品を焼成した以外は実施例３と同様に実施した結果、メタクロレイン反応率８７．５％、メタクリル酸選択率８５．９％、メタクリル酸収率７５．２％であった。
【００３４】
【発明の効果】
本発明のメタクリル酸合成用触媒は、触媒活性およびメタクリル酸の選択性に優れており、この触媒を用いることで収率よくメタクリル酸を製造することができた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catalyst for synthesizing methacrylic acid containing at least molybdenum and a method for producing methacrylic acid.
[0002]
[Prior art]
As a raw material for the synthesis method of methacrylic acid using a catalyst containing at least molybdenum, methacrolein, isobutyraldehyde and the like are used. In general, a methacrylic acid synthesis reaction using such raw materials is performed in a high-temperature gas phase using a fixed bed reactor. When using a fixed bed reactor, the catalyst is usually shaped to a certain size or more.
[0003]
Numerous proposals have been made regarding a method for producing a catalyst used for synthesizing methacrylic acid from methacrolein, particularly a molding method. For example, Japanese Patent Application Laid-Open No. 55-73347 discloses a method in which cellulose is mixed with catalyst powder, and Japanese Patent Application Laid-Open No. 60-150834 discloses a method in which graphite is mixed with catalyst powder and then extrusion molded. JP-A-8-10621 describes a method of forming a catalyst powder by adjusting the catalyst powder to 1 to 250 μm.
[0004]
[Problems to be solved by the invention]
However, the catalysts obtained by these methods are still insufficient in catalytic activity and selectivity for methacrylic acid as industrial catalysts, and further improvements are desired.
[0005]
Accordingly, an object of the present invention is to provide a catalyst for synthesizing methacrylic acid having excellent catalytic activity and selectivity for methacrylic acid, and a method for producing methacrylic acid using the catalyst.
[0006]
[Means for Solving the Problems]
The present invention provides a secondary molded product obtained by pulverizing a primary molded product obtained by primary molding a mixed solution containing at least molybdenum or a powdery dry product of an aqueous slurry, and secondary molding the pulverized product of the obtained primary molded product. It is a catalyst for methacrylic acid synthesis produced by firing at a temperature of 300 to 500 ° C. Moreover, this invention is a manufacturing method of methacrylic acid characterized by using said catalyst for methacrylic acid synthesis | combination.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The catalyst for synthesizing methacrylic acid of the present invention is not particularly limited as long as it is a composite oxide catalyst containing molybdenum as an essential component, but preferably the following formula (1),
Mo a P b Cu c V d X e Y f O g (1)
(In the formula, Mo, P, Cu, V and O represent molybdenum, phosphorus, copper, vanadium and oxygen, respectively, X is iron, cobalt, nickel, zinc, magnesium, calcium, strontium, barium, titanium, chromium, tungsten. At least one element selected from the group consisting of manganese, silver, boron, silicon, tin, lead, arsenic, antimony, bismuth, niobium, tantalum, zirconium, indium, sulfur, selenium, tellurium, lanthanum and cerium, Y Represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, where a, b, c, d, e, f and g represent the atomic ratio of each element, and a = 12 In this case, 0.1 ≦ b ≦ 3, 0.01 ≦ c ≦ 3, 0.01 ≦ d ≦ 3, 0 ≦ e ≦ 3, 0.01 ≦ f ≦ In it, g is the atomic ratio of oxygen required to satisfy the valence of each element.)
It has a composition represented by these.
[0008]
In the production of a catalyst for synthesizing methacrylic acid, a method for producing a powdery dry product used as a raw material for primary molding is particularly limited as long as it does not involve significant uneven distribution of components through a mixed solution or aqueous slurry containing at least molybdenum. For example, various methods such as a conventionally known coprecipitation method, evaporation to dryness method, and oxide mixing method can be used.
[0009]
The catalyst raw material used for the preparation of a mixed solution or an aqueous slurry (hereinafter referred to as catalyst raw material liquid) containing at least molybdenum is not particularly limited, and nitrates, carbonates, acetates, ammonium salts, oxides, halides of each element. Etc. can be used in combination. For example, ammonium paramolybdate, molybdenum trioxide, molybdic acid, molybdenum chloride, etc. can be used as the molybdenum raw material.
[0010]
In the present invention, the method for drying the catalyst raw material liquid is not particularly limited, and a box-type dryer, a spray dryer, a drum dryer, a slurry dryer, or the like can be used. In the present invention, the term “drying” refers to reducing the moisture from the catalyst raw material liquid to make it substantially solid, and the moisture content of the dried product obtained by drying is not particularly limited. Moreover, the shape of the dried substance immediately after drying is not specifically limited, For example, a powder form, block shape, etc. are mentioned.
[0011]
In the present invention, since it is necessary to primary-form a powdery dried product, if the dried product is not powdery or is not suitable in size even if it is powdery, the dried product is appropriately pulverized, etc. Powdered. The method for making the powder is not particularly limited, and generally a general pulverization method using various pulverizers is applied. The size of the powdery dried product is not particularly limited as long as it does not hinder primary molding described later, but it is preferable that there is no size that cannot pass through a sieve having a nominal size of 1 mm. Here, the nominal dimension refers to the length of one side of the mesh of the sieve.
[0012]
The method for primary molding of the powdery dried product thus obtained (hereinafter referred to as dry powder) is not particularly limited as long as it is a method for obtaining a molded product from the powdered material. Various molding methods such as extrusion molding and granulation can be applied. Further, at the time of molding, for the purpose of controlling the specific surface area, pore volume and pore distribution of the molded product with good reproducibility and increasing mechanical strength, for example, inorganic salts such as barium sulfate and ammonium nitrate, Dried conventionally known additives such as graphite and other lubricants, celluloses, starch, polyvinyl alcohol, stearic acid and other organic substances, silica sol, hydroxide sol such as alumina sol, whisker, glass fiber, carbon fiber and other inorganic fibers You may add suitably with respect to powder. In addition, the shape of the primary molded product obtained by the primary molding is not particularly limited, and examples thereof include arbitrary shapes such as a spherical shape, a columnar shape, a ring shape (cylindrical shape), and a plate shape. Although the magnitude | size of a primary molded product is not specifically limited, The magnitude | size which cannot pass the sieve of a nominal dimension 2mm is preferable.
[0013]
In the present invention, the method for pulverizing the primary molded product is not particularly limited, but generally, general pulverization methods using various pulverizers are applied. The size of the pulverized product of the primary molded product (hereinafter referred to as the primary molded powder) is not particularly limited as long as it does not interfere with the secondary molding described later, but there is no size that cannot pass through a sieve with a nominal size of 2 mm. Size is preferred.
[0014]
In the present invention, it is important to perform secondary molding of at least the primary molding powder, and it is preferable to secondary molding a mixture of the primary molding powder and the dry powder.
[0015]
The primary molding powder that is at least primary molding powder, such as primary molding powder that is secondary molded or a mixture of primary molding powder and dry powder, contains 5% by mass of primary molding powder that cannot pass through a sieve having a nominal size of 1 mm. It is preferable that it is contained above, and it is particularly preferable that 10% by mass or more is contained.
[0016]
By secondary molding of the primary molding powder, a preferable pore structure is expressed in the final catalyst, and a catalyst excellent in catalytic activity and selectivity of methacrylic acid can be obtained. In addition, when secondary-molding what mixed dry powder with primary molding powder, the ratio of primary molding powder in this mixture has preferable 10 mass% or more, and it is especially preferable that it is 20 mass% or more.
[0017]
The method of secondary molding is not particularly limited, and various molding methods can be applied as in the primary molding, but the same molding method as the primary molding method is preferable. Moreover, you may mix and shape | mold an additive similarly to the case of primary shaping | molding. The shape of the secondary molded product obtained by the secondary molding is not particularly limited, but the same shape as the primary molding is preferable.
[0018]
By firing the obtained secondary molded article at a temperature of 300 to 500 ° C., the catalyst for synthesizing methacrylic acid of the present invention is obtained. The calcination time is not particularly limited, but if it is too short, a good catalyst cannot be obtained.
[0019]
The reaction conditions for producing methacrylic acid using the catalyst thus obtained vary depending on the reaction raw materials and reaction methods used, but cannot be generally stated, but conventionally known reaction conditions are applied as they are. it can. Examples of the reaction raw material used include methacrolein and isobutyraldehyde.
[0020]
For example, the reaction conditions for producing methacrylic acid by filling the methacrylic acid synthesis catalyst of the present invention into a fixed bed reactor and subjecting methacrolein to gas phase catalytic oxidation with molecular oxygen are as follows. The concentration of methacrolein in the raw material gas is usually 1 to 20% by volume, preferably 3 to 10% by volume. The source gas may contain a small amount of impurities such as lower saturated aldehydes that do not substantially affect the reaction. Although it is industrially advantageous to use air as the molecular oxygen source, air enriched with pure oxygen can also be used if necessary. The amount of oxygen in the raw material gas is preferably 0.5 to 3 mol with respect to 1 mol of methacrolein. The source gas is preferably diluted with an inert gas, water vapor or the like. The reaction pressure is normal to several atmospheres. The reaction temperature is preferably 200 to 450 ° C.
[0021]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these Examples. “Parts” in Examples and Comparative Examples means parts by weight. Analysis of reaction products and the like was performed using gas chromatography. Moreover, the reaction rate of methacrolein, the selectivity of the produced methacrylic acid, and the yield were calculated by the following equations.
Reaction rate of methacrolein (%) = B / A × 100
Methacrylic acid selectivity (%) = C / B × 100
Methacrylic acid yield (%) = C / A × 100
Here, A represents the number of moles of methacrolein supplied, B represents the number of moles of reacted methacrolein, and C represents the number of moles of methacrylic acid produced.
[0022]
[Example 1]
100 parts of ammonium paramolybdate, 4.4 parts of ammonium metavanadate and 4.8 parts of potassium nitrate were dissolved in 400 parts of pure water. While stirring this, a solution prepared by dissolving 8.2 parts of 85 mass% phosphoric acid aqueous solution in 10 parts of pure water was added, and a solution prepared by dissolving 1.1 parts of copper nitrate in 10 parts of pure water was further added. Next, 7.0 parts of a 60 mass% nitric acid aqueous solution and 40 parts of pure water were added to 6.9 parts of bismuth nitrate, and the resulting uniform solution of bismuth nitrate was added to the mixed solution, followed by heating to 95 ° C. To this was added a solution prepared by dissolving 2.2 parts of a 60% by mass aqueous arsenic acid solution in 10 parts of pure water, followed by 2.1 parts of antimony trioxide and 1.6 parts of cerium dioxide. The obtained catalyst raw material liquid was evaporated to dryness while stirring with heating, and further dried at 130 ° C. for 16 hours to obtain a block-like dried product.
[0023]
This dried catalyst raw material was pulverized using a drag mill so that there was no size that could not pass through a sieve having a nominal size of 1 mm. A part of the dry powder thus obtained was set aside for use in secondary molding, and after adding 2 parts of graphite to the remaining 100 parts of dry powder, an outer diameter of 5 mm, Primary molding was performed in a ring shape having an inner diameter of 2 mm and a length of 5 mm. The obtained primary molded product was pulverized using a jaw crusher so that there was no size that could not pass through a sieve having a nominal size of 2 mm. 40 parts of the primary molding powder thus obtained and 60 parts of the dried powder that had been set aside were mixed to obtain a mixture for secondary molding. The proportion of the primary molding powder that cannot pass through a sieve having a nominal size of 1 mm in this mixture was 21% by mass.
[0024]
After adding 1 part of graphite to 100 parts of this mixture, it was secondarily 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 machine to obtain a secondary molded product. The secondary molded product was calcined at 380 ° C. for 5 hours under air flow to obtain a methacrylic acid synthesis catalyst. The composition of elements other than oxygen in this catalyst was Mo 12 P 1.5 V 0.8 Cu 0.1 Sb 0.3 Bi 0.3 As 0.2 Ce 0.2 K 1 .
[0025]
This catalyst was packed in a fixed bed reaction tube, and a raw material gas consisting of 5% by volume of methacrolein, 10% by volume of oxygen, 30% by volume of water vapor and 55% by volume of nitrogen was passed at a reaction temperature of 290 ° C. and a contact time of 3.6 seconds. When methacrylic acid was produced, the methacrolein reaction rate was 91.4%, the methacrylic acid selectivity was 88.6%, and the methacrylic acid yield was 81.0%.
[0026]
[Example 2]
In Example 1, except that 3 parts of the primary molding powder and 97 parts of the dry powder were mixed to obtain a mixture for secondary molding, the results were the same as in Example 1. As a result, the methacrolein reaction rate was 90.2%, methacrylic acid The selectivity was 88.3% and the yield of methacrylic acid was 79.6%. In addition, the ratio of the primary molding powder which cannot pass the sieve of a nominal dimension 1mm in the mixture for secondary shaping | molding at this time was 2 mass%.
[0027]
[Comparative Example 1]
As a result of carrying out in the same manner as in Example 1 except that the primary molded product was fired without performing the secondary molding, the methacrolein reaction rate was 90.0%, the methacrylic acid selectivity was 88.2%, and the methacrylic acid yield was 79.4. %Met.
[0028]
[Comparative Example 2]
As a result of carrying out in the same manner as in Comparative Example 1 except that a dried material of the catalyst raw material liquid was pulverized so that there was no size that could not pass through a sieve having a nominal size of 2 mm, a methacrolein reaction rate of 89.8 was obtained. %, Methacrylic acid selectivity 88.1%, and methacrylic acid yield 79.1%.
[0029]
[Example 3]
100 parts of ammonium paramolybdate, 2.8 parts of ammonium metavanadate and 9.2 parts of cesium nitrate were dissolved in 400 parts of pure water. While stirring this, a solution prepared by dissolving 8.2 parts of 85 mass% phosphoric acid aqueous solution in 10 parts of pure water and a solution prepared by dissolving 1.1 parts of telluric acid in 10 parts of pure water were added, and the mixture was stirred at 95 ° C. The temperature rose. Next, a solution of 3.4 parts of copper nitrate, 7.6 parts of ferric nitrate, 1.4 parts of zinc nitrate and 1.8 parts of magnesium nitrate in 80 parts of pure water was added. Furthermore, this mixed liquid was stirred at 100 ° C. for 30 minutes to obtain a catalyst raw material liquid.
[0030]
This catalyst raw material liquid was dried using a co-current type spray dryer under the conditions of a dryer inlet temperature of 300 ° C. and a rotating speed of a slurry spray rotating disk of 20000 rpm. The particle size of the dry powder thus obtained was in the range of 1 to 200 μm. A part of this dry powder is set aside for use in secondary molding, and after adding 3 parts of glass fiber to the remaining 100 parts of dry powder, the outer diameter is 5 mm, the inner diameter is 2 mm, and the length is reduced by a tableting machine. Primary molding was performed in a 3 mm ring shape. The primary molded product thus obtained was pulverized using a drag mill so that there was no size that could not pass through a sieve having a nominal size of 2 mm. 60 parts of the primary molding powder thus obtained and 40 parts of the dried powder that had been set aside were mixed to obtain a mixture for secondary molding. The proportion of the primary molding powder that cannot pass through a sieve having a nominal size of 1 mm in this mixture was 33% by mass.
[0031]
This mixture was secondarily molded into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and a length of 3 mm using a tableting machine to obtain a secondary molded product. The secondary molded product was calcined at 380 ° C. for 5 hours under air flow to obtain a methacrylic acid synthesis catalyst. The composition of elements other than oxygen in this catalyst was Mo 12 P 1.5 V 0.5 Cu 0.3 Fe 0.4 Te 0.1 Mg 0.15 Zn 0.1 Cs 1 .
[0032]
When this catalyst was packed in a fixed bed reaction tube and methacrylic acid was produced under the same reaction conditions as in Example 1, the methacrolein reaction rate was 88.7%, the methacrylic acid selectivity was 86.1%, and the methacrylic acid yield was 76. 4%.
[0033]
[Comparative Example 3]
As a result of carrying out in the same manner as in Example 3 except that the primary molded product was fired without performing the secondary molding, the methacrolein reaction rate was 87.5%, the methacrylic acid selectivity was 85.9%, and the methacrylic acid yield was 75.2. %Met.
[0034]
【The invention's effect】
The catalyst for synthesizing methacrylic acid of the present invention is excellent in catalytic activity and selectivity of methacrylic acid, and methacrylic acid can be produced with good yield by using this catalyst.
Claims (5)
ＭｏａＰｂＣｕｃＶｄＸｅＹｆＯｇ （１）
（式中、Ｍｏ、Ｐ、Ｃｕ、ＶおよびＯはそれぞれモリブデン、リン、銅、バナジウムおよび酸素を表し、Ｘは鉄、コバルト、ニッケル、亜鉛、マグネシウム、カルシウム、ストロンチウム、バリウム、チタン、クロム、タングステン、マンガン、銀、ホウ素、ケイ素、スズ、鉛、ヒ素、アンチモン、ビスマス、ニオブ、タンタル、ジルコニウム、インジウム、イオウ、セレン、テルル、ランタンおよびセリウムからなる群より選ばれた少なくとも１種の元素、Ｙはカリウム、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種の元素を表す。ただし、ａ、ｂ、ｃ、ｄ、ｅ、ｆおよびｇは各元素の原子比を表し、ａ＝１２のとき、０．１≦ｂ≦３、０．０１≦ｃ≦３、０．０１≦ｄ≦３、０≦ｅ≦３、０．０１≦ｆ≦３であり、ｇは前記各元素の原子価を満足するのに必要な酸素の原子比である。）The catalyst for synthesizing methacrylic acid according to claim 1, wherein the catalyst for synthesizing methacrylic acid is a composite oxide having a composition represented by the following formula (1).
Mo a P b Cu c V d X e Y f O g (1)
(Wherein Mo, P, Cu, V and O represent molybdenum, phosphorus, copper, vanadium and oxygen, respectively, X is iron, cobalt, nickel, zinc, magnesium, calcium, strontium, barium, titanium, chromium, tungsten At least one element selected from the group consisting of manganese, silver, boron, silicon, tin, lead, arsenic, antimony, bismuth, niobium, tantalum, zirconium, indium, sulfur, selenium, tellurium, lanthanum and cerium, Y Represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, where a, b, c, d, e, f and g represent the atomic ratio of each element, and a = 12 In this case, 0.1 ≦ b ≦ 3, 0.01 ≦ c ≦ 3, 0.01 ≦ d ≦ 3, 0 ≦ e ≦ 3, 0.01 ≦ f ≦ In it, g is the atomic ratio of oxygen required to satisfy the valence of each element.)
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| JP4933709B2 (en) * | 2001-09-26 | 2012-05-16 | 三菱レイヨン株式会社 | Method for producing catalyst for synthesis of unsaturated carboxylic acid |
| HUE042795T2 (en) * | 2003-06-13 | 2019-07-29 | Yara Int Asa | Method for producing supported oxide catalysts |
| KR100557640B1 (en) * | 2004-01-09 | 2006-03-10 | 주식회사 엘지화학 | Novel Heteropoly Acid Catalyst and Preparing Method Thereof |
| US7732367B2 (en) * | 2005-07-25 | 2010-06-08 | Saudi Basic Industries Corporation | Catalyst for methacrolein oxidation and method for making and using same |
| US7649112B2 (en) * | 2005-07-25 | 2010-01-19 | Saudi Basic Industries Corporation | Integrated plant for producing 2-ethyl-hexanol and methacrylic acid and a method based thereon |
| US7649111B2 (en) * | 2005-07-25 | 2010-01-19 | Saudi Basic Industries Corporation | Catalyst for the oxidation of a mixed aldehyde feedstock to methacrylic acid and methods for making and using same |
| MY186658A (en) * | 2016-06-21 | 2021-08-04 | Mitsubishi Chem Corp | Method for producing methacrylic acid production catalyst, method for producing methacrylic acid, and method for producing methacrylic acid ester |
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