1281418 (1) 玖、發明說明 【發明所屬之技術領域】 本發明係關於一種雜多酸觸媒再活化的方法，其係在 以異丁烯醛進行氣相觸媒氧化反應產製甲基丙烯酸時所使 用的觸媒。 【先前技術】 使異丁烯醛進行使用雜多酸觸媒之氣相觸媒氧化反應 的方法係迄今已知的其中一種產製甲基丙烯酸的方法。在 該反應中，觸媒活性經常隨反應時間流逝而逐漸下降。因 此，爲了延長觸媒壽命，故已硏究經由再活化法恢復觸媒 活性。例如，日本專利特許公開申請案第（JP-A058-15 635 1號係揭示一種在含有至少10體積％之水蒸汽的氣 流下以從70°C至24(TC之溫度的熱處理觸媒的方法，其係 含有自由磷鉬酸或自由磷釩鉬酸及已在會使其活性減低的 上述反應中用過的觸媒。而且，JP-A-6-76 85係揭示一種 在含有至少0.1體積％之分子氧的氣流下以從300°C至410 t之溫度的熱處理觸媒的方法，其係含有磷、鉬和釩及已 在會使其活性減低的上述反應中用過的觸媒。 但是這些慣用的方法可能未必展現滿意的觸媒活性恢 復效應，並在一些情況中，不可能獲得具有預期活性的再 活化觸媒。 【發明內容】 -6 - (2) 1281418 本發明的一個目的係提供一種用於產製甲基丙烯酸之 觸媒再活化的方法，該方法具有比慣用的方法更卓越的再 活化之觸媒活性。 在用心的硏究之後，本發明者發現在組合分子氧與水 蒸汽濃度之氣流中及用於再活化之溫度範圍的特殊條件下 以熱處理在上述反應中用過的觸媒可以達成以上的目的， 因此本發明者已完成本發明。 換言之，本發明係提供一種含有磷、鉬和釩及已在產 製甲基丙烯酸之異丁烯醛之氣相觸媒氧化反應中用過的雜 多酸觸媒再活化的方法，該方法包含在含有至少3體積％ 之分子氧及至少3體積％之水蒸汽的氣流下以從290°C至 4 00 °C之溫度的熱處理觸媒的步驟。 在本發明再活化的觸媒係含有磷、鉬和釩之雜多酸觸 媒。可在以異丁烯醛之氣相觸媒氧化反應進行甲基丙烯酸 的產製作用中使用該觸媒。觸媒可以包含自由雜多酸或可 以包含雜多酸的鹽。已提出許多關於產製甲基丙烯酸之雜 多酸觸媒的組成物、物性及製備方法的報告（參閱例如JP-A-59-12758 、 JP-A-60-239439 、 JP-A-5-96172 、 JP-A-8- 10621及JP-A-1 1-22641 1)。可以根據在報告中揭示的方 法獲得在本發明再活化的觸媒，但是不應該將該方法解釋 成對本發明範圍的限制。 以氣體原料（即異丁烯醛）與分子氧或水蒸汽一起供應 -7- 1281418 (3) 至以觸媒裝塡的固定床反應器中，可以進行使用雜多酸觸 媒的異丁烯醛之氣相觸媒氧化反應。在其工業產製作用中 ，可以使用多管型反應器作爲反應器。氣體原料可以包括 從1體積％至10體積％之異丁烯醛量、從3體積％至20 體積％之分子氧量、從5體積％至30體積％之水蒸汽量、 惰性氣體（如氮及二氧化碳）及類似物。可以使用空氣作爲 分子氧來源及可以使用蒸汽作爲水蒸汽來源。關於反應條 件，氣體原料的供應速度可以空間速度的名義從500至 5 000小時、以標準狀態爲基準；以下同上），即以每1公 升觸媒計之氣體原料的供應速度（公升/小時），以及反應溫 度可以從250至350 °C。可將在濃縮或與其包括的水分離 之後的反應產物氣體（包括所獲得的甲基丙烯酸）進行分離 及純化操作。可將回收的未反應之異丁烯醛作爲原料再循 環。可將若必要在燃燒之後的廢氣作爲上述的惰性氣體來 源再循環。 以異丁烯或特丁醇進行使用含有鉬、鉍和鐵之氧化物 觸媒的氣相觸媒氧化反應可以適當地產製作爲上述原料使 用的異丁烯醛。經由兩階段氣相觸媒氧化反應可以產製甲 基丙烯酸，其包含作爲第一階段反應的異丁烯或特丁醇的 氣相觸媒氧化反應及作爲第二階段反應的上述使用所生成 之異丁烯醛作爲原料的氣相觸媒氧化反應。以異丁烯或特 丁醇與分子氧一起供應至以觸媒塡充的固定床反應器中， 可以進行第一階段反應。在工業產製作用中，可以使用多 管型反應器作爲反應器。用於第一階段反應的氣體原料可 -8 - 1281418 (4) 以包括從2至10體積％之異丁烯或特丁醇、從3體積％至 20體積％之分子氧量、從0體積％至30體積％之水蒸汽量 、惰性氣體（如氮及二氧化碳）及類似物。可以使用空氣作 爲分子氧來源及可以使用蒸汽作爲水蒸汽來源。有可能使 用若必要在燃燒之後自第二階段反應回收的廢氣作爲惰性 氣體來源。關於第一階段反應的條件，氣體原料的供應速 度可以空間速度的名義從500至5000小時1及反應溫度 可以從300至400 °C。可將在第一階段反應所獲得的異丁 細進fT% 一階段反應的丨吴式大致分成兩種型式；第一種 係分離模式，其中將第一階段反應產物氣體進行分離操作 ，以獲得具有相當高純度之異丁烯醛，接著將其進行第二 階段反應；以及第二種係直接組合模式，其中將含有異丁 烯醛的第一階段反應產物氣體直接進行第二階段反應，不 進行分離操作[參閱例如”Petrochemical process”（由 The Japan Petroleum Institute 編輯，由 Kodansha Scientific Ltd·於 2001 年發表），第 174-175 頁]。 當異丁烯醛以上述方式進行在雜多酸觸媒存在下的氣 相觸媒氧化反應時，則經常使副產物牢固地黏在觸媒上或 使觸媒隨反應時間流逝而受到熱破壞，因此使觸媒活性逐 漸下降。在本發明中，在分別含有濃度不低於指定値之分 子氧及水蒸汽的氣流下以指定的溫度範圍的熱處理在上述 反應中用過的觸媒，以進行觸媒的再活化作用。 在用於觸媒熱處理的上述氣體中，分子氧濃度可以係 至少3體積％，並以10%體積％或更高較佳。當分子氧濃 1281418 (5) 度太低時，則再活化之觸媒活性可能夠不滿意。未特別限 制分子氧濃度的上限。但是，分子氧濃度可以高達約20 體積％，因爲方便使用空氣作爲分子氧來源。 而且，在用於觸媒熱處理的上述氣體中，水蒸汽濃度 可以係至少3體積％，並以8%體積％或更高較佳。當水蒸 汽濃度太低時，則再活化之觸媒活性可能不夠滿意。另一 方面’再活化之觸媒活性傾向於隨著水蒸汽濃度的增加而 增加。但是，在水蒸汽濃度達到超過3 0體積％時，則也 傾向於達到幾乎飽和的活性等級。因此，水蒸汽濃度的上 限可以高達3 0體積％。可以使用蒸汽作爲水蒸汽來源。 上述氣體的流速可以空間速度的名義從1〇至2000小 時_ 1，並以從1 0 0至1 0 0 0小時·1較佳。除了分子氧及水蒸 汽之外’用於觸媒熱處理的上述氣體可以包括惰性氣體， 如氮及二氧化碳。用於再活化之氣體可以不含異丁烯醛。 上述熱處理的溫度可以係290°C或更高，並以320°C 或更高較佳。反之，溫度可以係4〇〇°c或更低，並以37〇 C或更低較佳。不僅在溫度太低，並也在溫度太高時，所 得的處裡之觸媒可能具有不夠充份的活性。用於上述熱處 理的時間期限係依據其它條件而定，並可以從〇. 5至2〇 小時。 以自其中的觸媒已用過的反應器取出觸媒，將觸媒裝 入單獨準備的再活化容器中及接著將觸媒以熱處理的這種 方式可以進行觸媒的再活化處理，或者另一選擇係使觸媒 維持在反應器中及不自反應器取出的方式處理。但是，以 -10- 1281418 (6) 在反應與觸媒再活化作用之間轉換的可操作性觀點而言， 最好以後者的模式在反應器內進行再活化處理。 在上述的雜多酸觸媒之中，在本發明欲處理的觸媒係 以含有雜多酸之鹽的觸媒較佳，並以雜多酸之酸性鹽（部 份中和的鹽）最佳。 本發明的再活化法可以適合作爲在兩階段氣相觸媒氧 化反應中用於第二階段反應之觸媒再活化的方法使用，該 兩階段氣相觸媒氧化反應包含作爲第一階段反應的上述異 丁烯或特丁醇之氣相氧化反應及作爲第二階段反應的所得 異丁烯醛之氣相氧化反應。如以上所述，兩階段氣相氧化 反應可以包括分離模式（其中將異丁烯醛與具有相當高純 度的第一階段反應產物氣體分離及接著進行第二階段反應 )及直接組合模式（其中將含有異丁烯醛的第一階段反應產 物氣體直接進行第二階段反應，不進行分離操作）。本發 明的再活化法可以適用於在那些上述任何模式中的第二階 段反應之觸媒。本發明的再活化法在後者的直接組合模式 中特別展示明顯的觸媒活性恢復效應，因爲在該模式中， 幾乎將全部未反應的原料及包括在第一階段反應產物氣體 中的副產物引入第一階段反應器中，其容易造成減低第二 階段反應之觸媒活性。 在上述的兩階段氣相觸媒氧化反應中，不僅使第二階 段反應之觸媒，並也使第一階段反應之觸媒可能隨反應時 間流逝而逐漸喪失其觸媒活性。因此，在直接組合模式的 兩階段氣相觸媒氧化反應中，特別希望同時進行用於第一 -11 - 1281418 (7) 階段反應之觸媒的再活化作用與用於第二階段反應之觸媒 的再活化作用。在含有至少3體積％之分子氧（以從1 〇至 20體積％較佳）的氣流下以從360°C至45(TC之溫度（以從 3 60至400 °C較佳）的熱處理觸媒，可以適合進行用於第一 階段反應之觸媒的再活化作用。用於第一階段反應之觸媒 的再活化作用所使用的氣體可以包括水蒸汽，但不是必然 的。除了分子氧或水蒸汽之外，氣體可以包括惰性氣體， 如氮或二氧化碳。 以自其中的觸媒已用過的反應器取出觸媒，將觸媒裝 入單獨準備的再活化容器中及接著將觸媒以熱處理的這種 方式也可以進行用於第一階段反應之觸媒的再活化作用， 或者另一選擇係使觸媒維持在反應器中及不自反應器取出 的方式處理。但是，以在反應與觸媒再活化作用之間轉換 的可操作性觀點而言，最好以後者的模式在反應器內進行 再活化處理。 在直接組合模式的兩階段氣相觸媒氧化反應中，有可 能一起進行用於第一階段反應之觸媒的再活化作用與用於 第二階段反應之觸媒的再活化作用，其具有好的可操作性 及同時將觸媒維持在反應器中，因爲氣體容易以該次序流 經連續的第一階段反應器及第二階段反應器。例如，以其 中允許含有預定濃度之分子氧及水蒸汽的氣體流經連,續白勺 第一階段反應器及第二階段反應器，而且使在每一個反應 器中的每一個觸媒層溫度維持在預定溫度的方法可以進& 用於第一及第二階段反應之觸媒的再活化作用。另一選擇 -12· 1281418 (8) 係以其中允許含有預定濃度之分子氧的氣體流經連續的第 一階段反應器及第二階段反應器，而且使在每一個反應器 中的每一個觸媒層溫度維持在預定溫度，以及同時將含有 預定濃度之水蒸汽的氣體加在第二階段反應器入口的方法 可以進行觸媒的再活化作用。以含有分子氧之氣體引入連 續的第一階段反應器及第二階段反應器的方式進行這種觸 媒再活化作用有可能同時進行固體物質的去除，如可在從 第一階段反應器出口延伸至第二階段反應器入口的管道中 固化的含碳物質。 在以異丁烯或特丁醇與分子氧及水蒸汽一起供應至第 一階段反應器的方式進行直接組合模式的兩階段氣相觸媒 氧化反應時，則有可能將反應平順地轉換成觸媒再活化作 用，其係藉由在進行特定的反應時間之後終止異丁烯或特 丁醇的供應及接著在若必要時調整在供應的氣體中的分子 氧及水蒸汽濃度和調整在每一個反應器中的觸媒層溫度。 以逐漸增加第一階段反應溫度及第二階段反應溫度可 以進行直接組合模式的兩階段氣相觸媒氧化反應，尤其係 第一階段反應器及第二階段反應器之加熱介質溫度，其係 依據由於隨反應時間流逝而去活化之觸媒而定，以便於維 持分別在第一階段反應及第二階段反應中預定的轉化率。 因此，在該方法中，在第一階段反應器之加熱介質溫度成 爲3 6 0 °C或更高及第二階段反應器之加熱介質溫度成爲 29 0 °C或更高時終止異丁烯或特丁醇的供應，可以非常平 順地進行從反應轉換成觸媒再活化處理’可以在同時使兩 -13- 1281418 Ο) 種觸媒達到再活化處理必要的溫度時。最好以定期從每半 年一次至每年一次的頻率進行觸煤再活化作用。 根據本發明，有可能充份恢復已在異丁烯醛之氣相觸 媒氧化反應中用過的含有磷、鉬和釩之雜多酸觸媒的活性 及獲得具有極佳活性的再活化觸媒。 顯然可以各種方式改變因此所述的本發明。將這些變 化視爲在本發明的精神及範圍內，熟悉本技藝的人可能明 白所有這些修改係在以下的申請專利範圍內。 將在2002年4月16日提出申請的日本專利申請案第 2002-1 1308 1號的揭示全文（顯示專利說明書、申請專利範 圍及總結論）以其全文倂入本文以供參考。 【實施方式】 實例 以參考以下的實例更詳細說明本發明，不應該將其解 釋成對本發明範圍的限制。 參考實例1 (a)觸媒的製備作用 將38.2公斤硝酸鉋[CsN〇3]、10·2公斤硝酸銅三水合 物[Cu(N03)2 · 3Η20]、24.2公斤之85重量％正磷酸及 25.2公斤之70重量％硝酸溶解在加熱至40°C之224公斤 離子交換水中，以獲得所生成之溶液（液體A)。另一方面 ，在將297公斤鉬酸銨四水合物[(ΝΗ4)6Μο7〇24· 4H2〇]溶 -14- 1281418 (10) 解在加熱至40 °C之3 30公斤離子交換水中之後，將8.19 公斤偏釩酸銨[NH4V03]懸浮在其中，以獲得所生成之懸 浮液（液體B)。將液體A滴入攪拌下的液體B中，將10.2 公斤三氧化銻[Sb203]加入其中及接著在密封的容器中以 1 20 °C攪拌17小時，以獲得泥漿液。將泥漿液使用噴霧乾 燥器乾燥，以獲得觸媒前驅體粉末。將4份重量之陶瓷纖 維[由 Toshiba Monofrax有限公司製造的 FIBERFRAX RFC400SL]、8份重量之硝酸銨及10份重量之離子交換水 加入100份重量之粉末中、捏和及接著進行擠壓模塑，成 爲具有5毫米直徑及3毫米高度之圓筒形。在90 °C之溫 度及35 % RH之濕度下乾燥3小時之後，將模塑之物件在 220 °C之空氣流中煅燒22小時，在250 °C之空氣流中煅燒 1小時，在435 t之氮氣流中煅燒3小時及接著在39(TC 之空氣流中煅燒3小時，以該次序獲得觸媒。觸媒係由含 有分別以1.5、1 2、0 · 5、0.5、0.3和1 · 4之原子比的磷、 鉬、釩、銻、銅和絶之雜多酸的酸性鹽所組成的。 (b)製得的觸媒之活性試驗 將9公克以上獲得的觸媒塡入具有15微米內徑之玻 璃微反應器中。以混合異丁烯醛、空氣、蒸汽與氮所製備 的含有4體積％之異丁烯醛、12體積％之分子氧及17體 積％之水蒸汽的氣體原料以670小時〃之空間速度供應至 玻璃微反應器中，並以280 °C之烘箱溫度（其係用於加熱 微反應器之熔爐溫度，以下同上）進行活性試驗。在自開 -15- 1281418 (11) 始反應起流逝1小時時，異丁烯酸之轉化率係9 6 %及對甲 基丙烯酸之選擇率係78%。 參考實例2 (a)使用觸媒的反應 將含有分別以1 2、1、2.5、7.5和0 · 6之原子比的鉬 、鉍、鐵、鈷和絶之氧化物的1 3 0 0毫升模塑觸媒塡入具 有25微米內徑之鋼反應管中，以其作爲第一階段反應器 使用。將與參考實例1(a)相同的方式製得的1800毫升觸 媒塡入具有30微米內直徑之鋼反應管中，以其作爲第二 階段反應器使用。以混合異丁烯、空氣、蒸汽與氮所製備 的含有5體積％之異丁烯、12體積％之分子氧及7.5體積 %之水蒸汽的氣體原料以1200小時^之空間速度供應至第 一階段反應器中，以獲得所生成之第一階段反應產物氣體 ，接著將其與空及氮混合，成爲含有3.2體積％之異丁烯 醛、8.5體積％之分子氧及11體積％之水蒸汽的氣體，接 著將所生成之氣體以1〇〇〇小時1之空間速度供應至第二 階段反應器中，以進行兩階段氣相觸媒氧化反應。分別控 制在該操作期間的第一階段反應器及第二階段反應器之加 熱介質溫度，使得在第一階段反應中的異丁烯轉化率成爲 約99%及在第二階段反應中的異丁烯醛轉化率成爲72%或 更高。因此，將開始反應時的第二階段反應器之加熱介質 溫度設定成275 °C，並將自反應開始起流逝3000小時時 的溫度設定成293 °C。在此時終止反應，並自第二階段反 -16- 1281418 (12) 應器取出觸媒。以放在反應器入口起向內約1/3之部位上 的觸媒取樣。利用該樣品作爲在以下實例中用過的觸媒。 (b)用過的觸媒之活性試驗 以與參考實例1(b)相同的方式進行以上所獲得的用過 的觸媒之活性試驗。異丁烯醛轉化率係21%。用過的觸媒 具有0.6重量％之總碳量，反之，以參考實例1(a)所製備 的觸媒具有〇.〇%之總碳量。 實例1 以參考實例2(b)進行用過的觸媒之活性試驗之後，將 用過的觸媒以350 °C之烘箱溫度的熱處理15小時，同時 將以混合空氣、蒸汽與氮所製備的含有1 2體積％之分子 氧及18體積％之水蒸汽的氣體以500小時u之空間速度供 應至已塡入用過的觸媒之玻璃微反應器中。接著將熱處理 之後的觸媒進行與參考實例1(b)相同方式的活性試驗。異 丁烯醛轉化率係9 1 %。在熱處理之後的觸媒具有〇 . 0 %之 總碳量。 實例2至14及比較性實例1至4 將以參考實例2(a)所準備的用過的觸媒塡入具有15 微米內徑之玻璃微反應器中，接著將以混合空氣、蒸汽與 氮所製備的含有分子氧及水蒸汽（具有表1展示的濃度）的 氣體以500小時1之空間速度供應至微反應器中，並接著 -17- 1281418 (13) 以表1展示的烘箱溫度進行以表1展示的時間期限之熱處 理。接著以與參考實例1(b)相同的方式進行在熱處理之後 的觸媒活性試驗。將結果（異丁烯醛轉化率）展示在表1中 表1 分子氧(體積％) 水蒸汽(體積％) 烘箱溫度ct) 時間(/>時) 轉化率(％) 實例2 12 9 290 15 45 實例3 12 9 310 15 58 實例4 12 9 330 15 73 實例5 12 9 350 15 87 實例6 12 9 370 15 93 實例7 12 9 390 15 86 比較性實例1 12 9 410 15 31 比較性實例2 21 0 330 15 43 比較性實例3 20 2.5 330 15 64 實例8 19 9 330 15 73 實例9 17 18 330 15 80 實例10 15 30 330 15 82 實例11 10 50 330 15 82 比較性實例4 0 18 330 15 46 實例12 12 18 350 2 90 實例13 12 18 350 15 91 實例14 12 18 350 60 891281418 (1) Field of the Invention [Technical Field] The present invention relates to a method for reactivation of a heteropolyacid catalyst, which is produced by gas phase catalytic oxidation of methacrolein to produce methacrylic acid. The catalyst used. [Prior Art] A method of subjecting methacrolein to a gas phase catalytic oxidation reaction using a heteropoly acid catalyst is one of the methods known to date for producing methacrylic acid. In this reaction, the catalytic activity often decreases gradually as the reaction time elapses. Therefore, in order to prolong the life of the catalyst, it has been investigated to restore the catalytic activity by the reactivation method. For example, Japanese Patent Laid-Open Publication No. (JP-A058-15635) discloses a method of heat-treating a catalyst at a temperature of from 70 ° C to 24 (TC temperature) under a gas stream containing at least 10% by volume of water vapor. It contains free phosphomolybdic acid or free phosphorus vanadium molybdate and a catalyst which has been used in the above reaction which reduces its activity. Moreover, JP-A-6-76 85 discloses that it contains at least 0.1 volume. A method of heat-treating a catalyst at a temperature of from 300 ° C to 410 t under a stream of molecular oxygen, which contains phosphorus, molybdenum and vanadium and a catalyst which has been used in the above reaction which reduces its activity. However, these conventional methods may not necessarily exhibit a satisfactory catalytic activity recovery effect, and in some cases, it is impossible to obtain a reactivation catalyst having a desired activity. [Abstract] -6 - (2) 1281418 One object of the present invention Provided is a method for reactivation of a catalyst for producing methacrylic acid, which has a catalyst activity of reactivation which is superior to that of a conventional method. After careful study, the inventors discovered that molecular oxygen is combined. With water vapor concentration The present invention has been accomplished by the heat treatment of a catalyst used in the above reaction under special conditions for the temperature range for reactivation, and the present inventors have completed the present invention. In other words, the present invention provides a phosphorus-containing compound. And molybdenum and vanadium and a method for reactivation of a heteropolyacid catalyst which has been used in the gas phase catalyst oxidation reaction of methacrylic acid to produce methacrolein, the method comprising containing at least 3% by volume of molecular oxygen and at least The step of heat-treating the catalyst at a temperature of from 290 ° C to 400 ° C under a gas flow of 3 vol% of water vapor. The catalyst for reactivation in the present invention contains a heteropolyacid catalyst of phosphorus, molybdenum and vanadium. The catalyst may be used in the production of methacrylic acid by a gas phase catalyst oxidation reaction of methacrolein. The catalyst may contain a free heteropoly acid or a salt which may contain a heteropoly acid. A report on the composition, physical properties, and preparation method of a heteropoly acid catalyst based on acrylic acid (see, for example, JP-A-59-12758, JP-A-60-239439, JP-A-5-96172, JP-A-8 - 10621 and JP-A-1 1-22641 1). Can be reported according to The process disclosed herein obtains a catalyst that is reactivated in the present invention, but the method should not be construed as limiting the scope of the invention. A gaseous feedstock (i.e., methacrolein) is supplied with molecular oxygen or water vapor -7-1281418 (3) A gas phase catalyst oxidation reaction of methacrolein using a heteropolyacid catalyst can be carried out in a fixed bed reactor equipped with a catalyst. In the industrial production, a multitubular reactor can be used as a reaction. The gas feedstock may include from 1% by volume to 10% by volume of methacrolein, from 3% by volume to 20% by volume of molecular oxygen, from 5% by volume to 30% by volume of water vapor, and an inert gas such as nitrogen. And carbon dioxide) and the like. Air can be used as a source of molecular oxygen and steam can be used as a source of water vapor. Regarding the reaction conditions, the supply rate of the gaseous raw material can be from 500 to 5,000 hours in the nominal space velocity, based on the standard state; the same as above), that is, the supply rate of the gas raw material per liter of the catalyst (liters per hour) And the reaction temperature can be from 250 to 350 °C. The reaction product gas (including the obtained methacrylic acid) after being separated or separated from the water to be included may be subjected to separation and purification operations. The recovered unreacted methacrolein can be recycled as a raw material. The exhaust gas after combustion if necessary may be recycled as the above-mentioned inert gas source. The use of isobutylene or tert-butanol for the gas phase catalytic oxidation reaction using an oxide catalyst containing molybdenum, niobium and iron can be suitably carried out to produce methacrolein which is used as the above raw material. Methacrylic acid can be produced via a two-stage gas phase catalytic oxidation reaction comprising a gas phase catalyst oxidation reaction of isobutene or tert-butanol as a first-stage reaction and a methacrolein produced as described above for the second-stage reaction A gas phase catalyst oxidation reaction as a raw material. The first-stage reaction can be carried out by supplying isobutylene or tert-butyl alcohol together with molecular oxygen to a catalyst-charged fixed bed reactor. In the production of industrial products, a multi-tube type reactor can be used as the reactor. The gas feedstock for the first stage reaction may be -8 - 1281418 (4) to include from 2 to 10% by volume of isobutylene or tert-butanol, from 3 to 20% by volume of molecular oxygen, from 0 to % by volume 30% by volume of water vapor, inert gases (such as nitrogen and carbon dioxide) and the like. Air can be used as a source of molecular oxygen and steam can be used as a source of water vapor. It is possible to use exhaust gas recovered from the second-stage reaction after combustion as a source of inert gas. Regarding the conditions of the first-stage reaction, the supply rate of the gaseous raw material may be from 500 to 5000 hours in the nominal space velocity 1 and the reaction temperature may be from 300 to 400 °C. The isobutane obtained in the first-stage reaction can be roughly divided into two types by the fT% one-stage reaction; the first is a separation mode in which the first-stage reaction product gas is subjected to a separation operation to obtain Has a relatively high purity of methacrolein, which is then subjected to a second-stage reaction; and a second direct combination mode in which the first-stage reaction product gas containing methacrolein is directly subjected to the second-stage reaction without performing a separation operation [ See, for example, "Petrochemical process" (edited by The Japan Petroleum Institute, published by Kodansha Scientific Ltd., 2001), pp. 174-175]. When the methacrolein is subjected to the gas phase catalytic oxidation reaction in the presence of the heteropolyacid catalyst in the above manner, the by-product is often firmly adhered to the catalyst or the catalyst is thermally destroyed as the reaction time elapses. The catalytic activity is gradually reduced. In the present invention, the catalyst used in the above reaction is heat-treated at a specified temperature range under a gas flow containing not less than a specified molecular weight of oxygen and water vapor to carry out catalytic reactivation. In the above gas for the heat treatment of the catalyst, the molecular oxygen concentration may be at least 3% by volume, and preferably 10% by volume or more. When the molecular oxygen concentration 1281418 (5) is too low, the catalytic activity of the reactivation may be unsatisfactory. The upper limit of the molecular oxygen concentration is not particularly limited. However, the molecular oxygen concentration can be as high as about 20% by volume because air is conveniently used as a source of molecular oxygen. Further, in the above gas for the heat treatment of the catalyst, the water vapor concentration may be at least 3% by volume, and preferably 8% by volume or more. When the water vapor concentration is too low, the catalytic activity of the reactivation may not be satisfactory. On the other hand, the catalytic activity of reactivation tends to increase as the concentration of water vapor increases. However, when the water vapor concentration reaches more than 30% by volume, it tends to reach an almost saturated activity level. Therefore, the upper limit of the water vapor concentration can be as high as 30% by volume. Steam can be used as a source of water vapor. The flow rate of the above gas may be from 1 〇 to 2000 hr _ 1 in terms of space velocity, and preferably from 1 0 0 to 1 hour. In addition to molecular oxygen and water vapor, the above gases used for the heat treatment of the catalyst may include inert gases such as nitrogen and carbon dioxide. The gas used for reactivation may be free of methacrolein. The temperature of the above heat treatment may be 290 ° C or higher, and preferably 320 ° C or higher. Conversely, the temperature may be 4 〇〇 ° C or lower, and preferably 37 〇 C or lower. Not only when the temperature is too low, but also when the temperature is too high, the catalyst in the place may have insufficient activity. The time period for the above heat treatment is based on other conditions and may range from 〇. 5 to 2 〇 hours. The catalyst is taken out from the reactor in which the catalyst has been used, the catalyst is loaded into a separately prepared reactivation vessel, and then the catalyst is reheated by heat treatment in this manner, or another One option is to maintain the catalyst in the reactor and not in the reactor. However, in view of the operability of the conversion between the reaction and the catalyst reactivation of -10- 1281418 (6), it is preferable that the latter mode is subjected to reactivation treatment in the reactor. Among the above heteropolyacid catalysts, the catalyst to be treated in the present invention is preferably a catalyst containing a salt of a heteropoly acid, and the acid salt of a heteropoly acid (partially neutralized salt) is the most good. The reactivation method of the present invention can be suitably used as a method for catalyst reactivation of a second-stage reaction in a two-stage gas phase catalytic oxidation reaction comprising as a first-stage reaction A gas phase oxidation reaction of the above isobutylene or tert-butanol and a gas phase oxidation reaction of the obtained methacrolein as a second-stage reaction. As described above, the two-stage gas phase oxidation reaction may include a separation mode in which the methacrolein is separated from the first-stage reaction product gas having a relatively high purity and then a second-stage reaction, and a direct combination mode in which isobutylene is contained. The first stage reaction product gas of the aldehyde is directly subjected to the second stage reaction without performing the separation operation). The reactivation method of the present invention can be applied to a catalyst for the second stage reaction in any of the above modes. The reactivation method of the present invention particularly exhibits a significant catalytic activity recovery effect in the direct combination mode of the latter, since in this mode almost all of the unreacted starting materials and by-products included in the first stage reaction product gas are introduced In the first stage reactor, it is easy to cause the catalyst activity to reduce the second stage reaction. In the above two-stage gas phase catalyst oxidation reaction, not only the catalyst for the second stage reaction but also the catalyst of the first stage reaction may gradually lose its catalytic activity as the reaction time elapses. Therefore, in the two-stage gas phase catalyst oxidation reaction in the direct combination mode, it is particularly desirable to simultaneously carry out the reactivation of the catalyst for the first stage 11-1181418 (7) reaction and the contact for the second stage reaction. Reactivation of the medium. Heat treatment at a temperature of from 360 ° C to 45 (preferably from 3 60 to 400 ° C) at a gas flow containing at least 3% by volume of molecular oxygen (preferably from 1 Torr to 20 vol%) The medium may be suitable for reactivation of the catalyst for the first stage reaction. The gas used for the reactivation of the catalyst for the first stage reaction may include water vapor, but is not inevitable. In addition to molecular oxygen or In addition to water vapor, the gas may include an inert gas such as nitrogen or carbon dioxide. The catalyst is taken out of the reactor from which the catalyst has been used, the catalyst is loaded into a separately prepared reactivation vessel and then the catalyst is This method of heat treatment can also be carried out by reactivation of the catalyst for the first stage reaction, or alternatively, the catalyst can be maintained in the reactor and not taken out of the reactor. From the viewpoint of operability between conversion and catalyst reactivation, it is preferable that the latter mode be reactivated in the reactor. In the two-stage gas phase catalytic oxidation reaction in the direct combination mode, there is a possibility Reactivation of the catalyst for the first-stage reaction and reactivation of the catalyst for the second-stage reaction, which has good operability and at the same time maintains the catalyst in the reactor because the gas is easy Flowing through the continuous first-stage reactor and the second-stage reactor in this order, for example, by allowing a gas containing a predetermined concentration of molecular oxygen and water vapor to flow through the continuous, first-stage reactor and second The stage reactor, and the method of maintaining the temperature of each of the catalyst layers in each of the reactors at a predetermined temperature, can be used to reactivate the catalyst for the first and second stage reactions. Another option - 12· 1281418 (8) is a gas in which a predetermined concentration of molecular oxygen is allowed to flow through a continuous first-stage reactor and a second-stage reactor, and the temperature of each catalyst layer in each reactor is maintained. The method of re-activation of the catalyst at a predetermined temperature and simultaneously adding a gas containing a predetermined concentration of water vapor to the inlet of the second-stage reactor may be carried out by a gas containing molecular oxygen. This catalyst reactivation is carried out in the form of a continuous first-stage reactor and a second-stage reactor. It is possible to simultaneously remove solid matter, such as from the first stage reactor outlet to the second stage reactor inlet. a solid carbonaceous material in a pipeline. It is possible to carry out a two-stage gas phase catalytic oxidation reaction in a direct combined mode by supplying isobutene or tert-butanol together with molecular oxygen and water vapor to the first-stage reactor. Converting the reaction smoothly into catalyst reactivation by terminating the supply of isobutylene or tert-butanol after a specific reaction time and then adjusting the molecular oxygen and water vapor concentration in the supplied gas if necessary And adjusting the temperature of the catalyst layer in each reactor. The two-stage gas phase catalytic oxidation reaction of the direct combination mode can be carried out by gradually increasing the first-stage reaction temperature and the second-stage reaction temperature, especially the first-stage reactor. And the temperature of the heating medium of the second-stage reactor, which is determined by the catalyst that is deactivated as the reaction time elapses, so that Maintain respective predetermined reaction in the first stage and the second stage reaction conversion. Therefore, in the method, the isobutene or the tertene is terminated when the temperature of the heating medium of the first stage reactor becomes 3 60 ° C or higher and the temperature of the heating medium of the second stage reactor becomes 29 0 ° C or higher. The supply of alcohol can be carried out very smoothly from the reaction to the catalyst reactivation treatment, which can simultaneously bring the two 13-1381418 Ο catalysts to the temperature necessary for the reactivation treatment. It is preferable to carry out the reactivation of coal by periodically from the frequency of once every half year to once a year. According to the present invention, it is possible to sufficiently recover the activity of a heteropolyacid catalyst containing phosphorus, molybdenum and vanadium which has been used in the oxidation reaction of the gas phase catalyst of methacrolein and to obtain a reactivation catalyst having excellent activity. It is apparent that the invention thus described can be varied in various ways. It is to be understood that those skilled in the art will recognize that such modifications are within the scope of the following claims. The entire disclosure of the Japanese Patent Application No. 2002-1 1308, filed on Apr EXAMPLES The present invention is illustrated in more detail by reference to the following examples, which should not be construed as limiting the scope of the invention. Reference Example 1 (a) Preparation of catalyst: 38.2 kg of nitric acid planing [CsN〇3], 10.2 kg of copper nitrate trihydrate [Cu(N03)2 · 3Η20], 24.2 kg of 85 wt% orthophosphoric acid and 25.2 kg of 70% by weight nitric acid was dissolved in 224 kg of ion-exchanged water heated to 40 ° C to obtain the resulting solution (Liquid A). On the other hand, after dissolving 297 kg of ammonium molybdate tetrahydrate [(ΝΗ4)6Μο7〇24·4H2〇]-14-1281418 (10) in 3 30 kg of ion-exchanged water heated to 40 ° C, 8.19 kg of ammonium metavanadate [NH4V03] was suspended therein to obtain the resulting suspension (Liquid B). Liquid A was dropped into the liquid B under stirring, and 10.2 kg of antimony trioxide [Sb203] was added thereto and then stirred at 1, 20 ° C for 17 hours in a sealed vessel to obtain a slurry. The slurry was dried using a spray dryer to obtain a catalyst precursor powder. 4 parts by weight of ceramic fiber [FIBERFRAX RFC400SL manufactured by Toshiba Monofrax Co., Ltd.], 8 parts by weight of ammonium nitrate and 10 parts by weight of ion-exchanged water were added to 100 parts by weight of the powder, kneaded and then subjected to extrusion molding. It has a cylindrical shape with a diameter of 5 mm and a height of 3 mm. After drying at a temperature of 90 ° C and a humidity of 35% RH for 3 hours, the molded article was calcined in an air stream at 220 ° C for 22 hours, and calcined in an air stream at 250 ° C for 1 hour at 435 t. The calcination was carried out for 3 hours in a nitrogen stream and then calcined in a stream of 39 (TC) for 3 hours to obtain a catalyst in this order. The catalyst system was contained at 1.5, 1, 2, 0.5, 0.5, 0.3 and 1 respectively. An atomic ratio of phosphorus, molybdenum, vanadium, niobium, copper, and an acidic salt of a heteropolyacid. (b) Activity test of the obtained catalyst. The catalyst obtained by injecting 9 g or more has 15 In a glass microreactor of micron inner diameter, a gas raw material containing 4% by volume of methacrolein, 12% by volume of molecular oxygen and 17% by volume of water vapor prepared by mixing methacrolein, air, steam and nitrogen for 670 hours The space velocity of the crucible is supplied to the glass microreactor, and the activity test is carried out at an oven temperature of 280 ° C, which is used to heat the temperature of the microreactor, as described above. In self-opening -15-1281418 (11) When the initial reaction started for 1 hour, the conversion of methacrylic acid was 96% and p-methacrylic acid. The acid selectivity was 78%. Reference Example 2 (a) The reaction using a catalyst will contain molybdenum, ruthenium, iron, cobalt and oxidized atomic ratios of 1, 2, 1, 2.5, 7.5 and 0.6, respectively. 13,000 ml of the molding catalyst was poured into a steel reaction tube having an inner diameter of 25 μm, which was used as a first-stage reactor. 1800 ml obtained in the same manner as in Reference Example 1 (a) The catalyst is immersed in a steel reaction tube having an inner diameter of 30 μm and used as a second-stage reactor. 5% by volume of isobutylene and 12% by volume of molecular oxygen prepared by mixing isobutylene, air, steam and nitrogen And a gas raw material of 7.5 vol% of water vapor is supplied to the first-stage reactor at a space velocity of 1200 hours to obtain the first-stage reaction product gas generated, and then mixed with air and nitrogen to become 3.2. a volume % of methacrolein, 8.5 vol% molecular oxygen, and 11 vol% of water vapor gas, and then the generated gas is supplied to the second-stage reactor at a space velocity of 1 〇〇〇 1 to carry out two Stage gas phase catalyst oxidation reaction. Controlling the heating medium temperature of the first-stage reactor and the second-stage reactor during the operation so that the isobutylene conversion rate in the first-stage reaction becomes about 99% and the methacrolein conversion rate in the second-stage reaction becomes 72% or more. Therefore, the temperature of the heating medium of the second-stage reactor at the start of the reaction was set to 275 ° C, and the temperature at the time of 3000 hours from the start of the reaction was set to 293 ° C. The reaction was taken out from the second stage of the anti-16-1681418 (12) reactor. The catalyst was sampled at about 1/3 of the inward of the reactor inlet. This sample was used as a catalyst used in the following examples. (b) Activity test of used catalyst The activity test of the used catalyst obtained above was carried out in the same manner as in Reference Example 1 (b). The conversion of methacrolein was 21%. The used catalyst had a total carbon amount of 0.6% by weight, whereas the catalyst prepared in Reference Example 1 (a) had a total carbon amount of 〇.〇%. Example 1 After the activity test of the used catalyst was carried out with reference to Example 2 (b), the used catalyst was heat-treated at an oven temperature of 350 ° C for 15 hours while being prepared by mixing air, steam and nitrogen. A gas containing 12% by volume of molecular oxygen and 18% by volume of water vapor was supplied to the glass microreactor into which the spent catalyst had been introduced at a space velocity of 500 hours u. The catalyst after the heat treatment was then subjected to an activity test in the same manner as in Reference Example 1 (b). The conversion of methacrolein was 91%. The catalyst after the heat treatment has a total carbon amount of 〇. 0%. Examples 2 to 14 and Comparative Examples 1 to 4 The used catalyst prepared in Reference Example 2 (a) was poured into a glass microreactor having an inner diameter of 15 μm, followed by mixing air, steam and nitrogen. The prepared gas containing molecular oxygen and water vapor (having the concentration shown in Table 1) was supplied to the microreactor at a space velocity of 500 hours 1 and then -17-1281418 (13) at the oven temperature shown in Table 1. Heat treatment in the time period shown in Table 1. The catalyst activity test after the heat treatment was then carried out in the same manner as in Reference Example 1 (b). The results (metacrolein conversion) are shown in Table 1. Table 1 Molecular oxygen (% by volume) Water vapor (% by volume) Oven temperature ct) Time (/>) Conversion rate (%) Example 2 12 9 290 15 45 Example 3 12 9 310 15 58 Example 4 12 9 330 15 73 Example 5 12 9 350 15 87 Example 6 12 9 370 15 93 Example 7 12 9 390 15 86 Comparative Example 1 12 9 410 15 31 Comparative Example 2 21 0 330 15 43 Comparative Example 3 20 2.5 330 15 64 Example 8 19 9 330 15 73 Example 9 17 18 330 15 80 Example 10 15 30 330 15 82 Example 11 10 50 330 15 82 Comparative Example 4 0 18 330 15 46 Example 12 12 18 350 2 90 Example 13 12 18 350 15 91 Example 14 12 18 350 60 89
-18- 1281418 (14) 實例15 以與參考實例2(a)相同的方式再進行兩階段氣相觸媒 氧化反應。在自反應開始起流逝7 2小時時，將第一階段 反應器及第二階段反應器之加熱介質溫度分別設定成348 °C及27 5 °C，並在自反應開始起流逝6000小時時，將第 一階段反應器及第二階段反應器之加熱介質溫度分別設定 成362°C及294°C。此時在第一階段反應中的異丁烯轉化 率係 99.0%及在第二階段反應中的異丁烯醛轉化率係 7 3.2% 在該階段暫時終止反應，並進行用於第一階段反應之 觸媒及用於第二階段反應之觸媒的再活化作用。尤其將以 混合空氣、蒸汽與氮所製備的含有1 4體積％之分子氧及 1 8體積％之水蒸汽的氣體以使得在第一階段反應器中的空 間速度成爲690小時4及在第二階段反應器中的空間速度 成爲500小時u的方式流經連續的第一階段反應器及第二 階段反應器。接著將第一階段反應器及第二階段反應器的 加熱介質溫度分別緩慢增加至370°C及350°C，並維持10 小時。 接著將第一階段反應器及第二階段反應器之加熱介質 溫度分別設定成350°C及288°C，並在與那些參考實例2 相同的條件下重新開始兩階段氣相觸媒氧化反應。在自反 應重新開始起流逝2200小時時，將第一階段反應器及第 二階段反應器之加熱介質溫度分別設定成354 °C及289 °C 。此時在第一階段反應中的異丁烯轉化率係9 9.2 %及在第 -19- 1281418 (15) 二階段反應中的異丁烯醛轉化率係80.3%。 實例16 在進行參考實例2(a)的兩階段氣相觸媒氧化反應之後 ，將第一階段反應器中的觸媒保留其原來的樣子，並將在 第二階段反應器中的觸媒換成以參考實例1(a)所製備的新 鮮觸媒。接著在與那些參考實例2相同的條件下再進行兩 階段氣相觸媒氧化反應。在自反應重新開始起流逝4000 小時時，將第一階段反應器及第二階段反應器之加熱介質 溫度分別設定成363 °C及292°C。此時在第一階段反應中 的異丁烯轉化率係98.9 %及在第二階段反應中的異丁烯醛 轉化率係7 2.6 %。 在此時只終止異丁烯的供應，並將第一階段反應器及 第二階段反應器之加熱介質溫度分別在363 °C及292 °C下 維持2小時。 然後重新供應異丁烯，開始反應。在自反應重新開始 起流逝 20小時時，第一階段反應的異丁烯轉化率係 9 9.7%及第二階段反應的異丁烯醛轉化率係85.8%。 -20--18- 1281418 (14) Example 15 A two-stage gas phase catalytic oxidation reaction was carried out in the same manner as in Reference Example 2 (a). When the temperature of the heating medium of the first-stage reactor and the second-stage reactor was set to 348 ° C and 27 5 ° C, respectively, from the start of the reaction for 7 hours, and 6000 hours after the start of the reaction, The heating medium temperatures of the first-stage reactor and the second-stage reactor were set to 362 ° C and 294 ° C, respectively. At this time, the isobutylene conversion rate in the first-stage reaction is 99.0% and the methacrolein conversion rate in the second-stage reaction is 7 3.2%. The reaction is temporarily terminated at this stage, and the catalyst for the first-stage reaction is carried out. Reactivation of the catalyst for the second stage reaction. In particular, a gas containing 14% by volume of molecular oxygen and 18% by volume of water vapor prepared by mixing air, steam and nitrogen is used so that the space velocity in the first-stage reactor becomes 690 hours 4 and in the second The space velocity in the stage reactor was passed through a continuous first-stage reactor and a second-stage reactor in such a manner that the space velocity became 500 hours. The temperature of the heating medium of the first-stage reactor and the second-stage reactor was then slowly increased to 370 ° C and 350 ° C, respectively, and maintained for 10 hours. Next, the heating medium temperatures of the first-stage reactor and the second-stage reactor were set to 350 ° C and 288 ° C, respectively, and the two-stage gas phase catalytic oxidation reaction was restarted under the same conditions as those of Reference Example 2. The heating medium temperatures of the first-stage reactor and the second-stage reactor were set to 354 ° C and 289 ° C, respectively, for 2,200 hours from the start of the reaction. At this time, the isobutylene conversion rate in the first-stage reaction was 99.2% and the methacrolein conversion rate in the -19-1281418 (15) two-stage reaction was 80.3%. Example 16 After carrying out the two-stage gas phase catalytic oxidation reaction of Reference Example 2 (a), the catalyst in the first stage reactor was retained in its original state, and the catalyst in the second stage reactor was exchanged. The fresh catalyst prepared in Reference Example 1 (a) was prepared. Then, a two-stage gas phase catalytic oxidation reaction was carried out under the same conditions as those of Reference Example 2. The heating medium temperatures of the first-stage reactor and the second-stage reactor were set to 363 ° C and 292 ° C, respectively, for 4000 hours from the start of the reaction. At this time, the isobutylene conversion rate in the first-stage reaction was 98.9 % and the methacrolein conversion rate in the second-stage reaction was 7 2.6%. At this time, only the supply of isobutylene was terminated, and the heating medium temperatures of the first-stage reactor and the second-stage reactor were maintained at 363 ° C and 292 ° C for 2 hours, respectively. The isobutene is then re-supplied and the reaction begins. The isobutene conversion in the first stage reaction was 99.7% and the methacrolein conversion rate in the second stage reaction was 85.8%, 20 hours after the start of the reaction. -20-