593304 A7 __B7___ --. '- j 五、發明說明（i ) 【發明之詳細說明】 (請先閱讀背面之注意事項再填寫本頁) 【發明所屬之技術領域】 本發明係關於酸酐之製造方法。詳言之係關於’使用 多管式固定床反應器，將芳香族化合物藉由分子狀氧或含 分子狀氧之氣體進行接觸氣相氧化’以高產率來製造酸酐 之方法。 【習知技術】 酸酐爲當做可塑劑、塗料、樹脂、醫藥品、化粧品等 原料屬有用之化合物，在工業上係使芳香族化合物/空氣 混合氣體在多管式反應器中流動，以充塡於反應器中之觸 媒進行接觸氣相氧化之方法來製造。但是，於該製造方法 ，雖藉由選用最適化的觸媒能以高產率製得所望產物，但 常生成少量副產物。此副產物成爲製品純度減低、製品著 色、及管路閉塞等工廠事故等之原因，而此等問題及其解 決費用成爲製造成本增加之主要原因。 例如於鄰二甲苯等的鄰二烷基苯之氣相氧化來製造酞 酸酐時，伴隨肽酸酐會生成馬來酸、苯甲酸、苯肽等副產 物，造成所望物之酞酸酐之產率減低、或肽酸酐著色而使 品質降低。爲去除此等副產物而需要增加製程或設備等， 則發生製造成本增加之問題。此等副產物最好全部抑制其 生成，尤其苯肽很難用吸收及精製之製程予以去除，所以 必須以反應本身來抑制其生成，通常係採用將苯駄發生量 抑制在一定量以下之反應條件進行運轉。在進行萘之氣相 氧化來製造肽酸酐時，所生成之副產物之萘醌尤成爲問題 4 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐）~' " ---' 593304 κι ____Β7_ _ 五、發明說明（>) 。又進行苯之氣相氧化來製造馬來酸酐時，所生成之副產 物之苯醌尤成爲問題。而進行硬炔（durain)等四烷基苯或 2,4,5-三甲基苯甲醛等三烷基苯醛之氣相氧化來製造均苯 四甲酸酐時，所生成之副產物之偏苯三酸酐尤成爲問題。 使用於製造酸酐之觸媒通常爲能夠抑制副產物生成且 能夠提高產率之觸媒，但經長期使用時其觸媒活性會減低 ，隨時間的經過副產物會增加。以往爲減少副產物生成而 採用提高反應溫度之方法，但此方法成爲所望之酸酐產率 減低之原因，又會促進觸媒劣化，故由觸媒壽命之觀點， 希望使用不提高反應溫度而能減少副產物生成之方法。 爲解決上述問題，以酞酸酐爲例，德國專利第 19807018A1號說明書（1998)及德國專利第2005969A號說 明書（1970)揭示使用兩個分離之反應器之方法，亦即使用 第1反應器爲鹽冷卻式反應器、第2反應器爲無冷卻裝置 之後反應器等兩個反應器進行反應之方法。於該技術，第 2反應器爲利用與第1反應器相同或不同之觸媒所運轉之 固定床反應器，進入第2反應器中之插入物質流僅限自第 1反應器所流入之氣體流。於第2反應器中雖以無鹽浴冷 卻的方式進行絕熱反應，但第2反應器爲可使第1反應器 之溫度降低者，鹽浴溫度爲較標準條件低5〜10°C，並以 在第1反應器與第2反應器之間配置冷卻器爲較佳形態。 日本專利特開平4 - 224573號公報中揭示了在不同鹽 浴溫度控制之2個以上之連續之反應區域中將鄰二甲苯氧 化來製造狀酸酐之方法中，控制後部反應區域之鹽浴溫度 5 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） (請先閱讀背面之注意事項再填寫本頁) tl· 線- 593304 A7 _____B7__- 五、發明說明（$ ) 使其較最初之反應區域之鹽浴溫度低2〜20°C以進行反應 〇 於上述各技術，均設法使導入第2反應部之氣體溫度 減低爲第1反應器之反應溫度以下，期能抑制副產物生成 並提升酞酸酐產率。但爲減低第2反應器之氣體溫度需要 在第1反應器與第2反應器之間設置冷卻器或使用不同溫 度之鹽浴，不僅裝置費用增加，同時在現有工廠因設備配 置上之問題而有實施困難之情形。 德國專利第4014415C2號說明書（1991)揭示了一種使 得在肽酸酐及馬來酸酐等之製程中生成之經冷卻之載氣所 含有害環境成分進行接觸氧化之裝置。此裝置使用3支熱 交換管以冷卻通過觸媒後之高溫純氣體，將取得之熱有效 使用於載氣之預熱。又美國專利第3053854號說明書 (1962)所揭示之肽酸酐精製方法中，係包含一讓擇自萘及 鄰二甲苯所構成群之烴類於釩觸媒存在下以氣相與分子狀 氧進行反應來得到含肽酸酐與分子狀氧之氣體狀流出物之 製程，在改善對策方面，係提出包含：讓所得之氣體狀流 出物於150〜450°C與擇自鈷及錳所構成群中之觸媒接觸之 製程、將該接觸後之氣體狀流出物加以冷卻之製程、及由 該冷卻之氣體狀流出物濃縮實質上純質之肽酸酐之製程之 技術。但於此等技術因需要熱交換器等新設備，因此在減 低製造裝置之建造成本，基於工廠設備配置之考量使該等 裝置容易引進現有工廠，及以反應本身來抑制苯酞等之生 成以有效製造肽酸野等方面尙有改善空間。 6 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） (請先閱讀背面之注意事項再填寫本頁)593304 A7 __B7___-. '-J V. Description of the invention (i) [Detailed description of the invention] (Please read the notes on the back before filling out this page) [Technical field to which the invention belongs] The present invention relates to a method for producing acid anhydride . More specifically, it relates to a method for producing an acid anhydride in a high yield by using a multi-tubular fixed bed reactor to contact an aromatic compound with molecular oxygen or a gas containing molecular oxygen by gas-phase oxidation. [Known technology] Anhydride is a compound useful as a raw material for plasticizers, coatings, resins, pharmaceuticals, cosmetics, etc. In the industry, an aromatic compound / air mixed gas is flowed in a multi-tubular reactor to fill it. The catalyst in the reactor is produced by contact gas phase oxidation. However, in this manufacturing method, although a desired product can be obtained in a high yield by selecting an optimized catalyst, a small amount of by-product is often produced. This by-product has become the cause of factory accidents such as reduced product purity, product color, and pipeline occlusion, and these problems and their resolution costs have become the main reason for the increase in manufacturing costs. For example, in the production of phthalic anhydride by gas-phase oxidation of o-dialkylbenzene such as o-xylene, by-products such as maleic acid, benzoic acid, and phenyl peptide are generated with the peptidic anhydride, resulting in a reduction in the desired yield of phthalic anhydride. , Or the peptidic anhydride is colored to reduce the quality. In order to remove these by-products, it is necessary to add a process or equipment, and a problem arises that the manufacturing cost increases. These by-products are best to inhibit their production, especially phenyl peptides are difficult to remove by absorption and purification processes, so the reaction itself must be used to suppress their production. Usually, the reaction is used to suppress the amount of phenylhydrazone below a certain amount. Conditions to run. In the gas phase oxidation of naphthalene to produce peptidic anhydride, naphthoquinone produced as a by-product is particularly problematic. 4 This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) ~ '"- -'593304 κι ____ Β7_ _ 5. Description of the invention (>). When gas phase oxidation of benzene is performed to produce maleic anhydride, benzoquinone is produced as a by-product, which becomes a problem. In the production of pyromellitic anhydride by gas-phase oxidation of tetraalkylbenzenes such as hard acetylene (durain) or trialkylbenzaldehydes such as 2,4,5-trimethylbenzaldehyde, trimellitic anhydride is produced as a by-product. Especially problematic. The catalysts used in the manufacture of anhydrides are usually catalysts that can inhibit the formation of by-products and can increase the yield, but their catalytic activity will decrease during long-term use, and by-products will increase over time. In the past, a method of increasing the reaction temperature was used to reduce the formation of by-products. However, this method has become the cause of the desired decrease in the anhydride yield and promotes the deterioration of the catalyst. Therefore, from the viewpoint of the life of the catalyst, it is desirable to use it without increasing the reaction temperature. Methods to reduce by-products. To solve the above problems, taking phthalic anhydride as an example, German Patent No. 19807018A1 (1998) and German Patent No. 2005969A (1970) disclose a method using two separate reactors, that is, using the first reactor as a salt The cooling reactor and the second reactor are methods in which two reactors, such as a reactor without a cooling device, perform a reaction. In this technology, the second reactor is a fixed-bed reactor operated with the same or different catalyst as the first reactor, and the flow of the inserted material into the second reactor is limited to the gas flowing from the first reactor flow. In the second reactor, although the adiabatic reaction is performed by cooling in a salt-free bath, the second reactor can reduce the temperature of the first reactor. The temperature of the salt bath is 5 to 10 ° C lower than the standard conditions. A cooler is preferably arranged between the first reactor and the second reactor. Japanese Patent Laid-Open No. 4-224573 discloses that in a method for producing acid anhydride by oxidizing o-xylene in two or more consecutive reaction zones controlled by different salt bath temperatures, the salt bath temperature in the rear reaction zone is controlled This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) (please read the precautions on the back before filling this page) tl·line-593304 A7 _____ B7 __- 5. Description of the invention ($) The temperature of the salt bath in the initial reaction zone was lowered by 2 to 20 ° C to perform the reaction. In each of the above techniques, the temperature of the gas introduced into the second reaction section was reduced below the reaction temperature of the first reactor, and the by-products could be suppressed in the future. Production and improvement of phthalic anhydride yields. However, in order to reduce the gas temperature of the second reactor, it is necessary to install a cooler between the first reactor and the second reactor or use a salt bath with a different temperature, which not only increases the equipment cost, but also causes problems in the existing plant due to equipment configuration problems. There are situations where implementation is difficult. The specification of German Patent No. 4014415C2 (1991) discloses a device for contact oxidation of environmentally-friendly components contained in a cooled carrier gas generated in a process such as peptide anhydride and maleic anhydride. This device uses 3 heat exchange tubes to cool the high temperature pure gas after passing through the catalyst, and the obtained heat is effectively used for the preheating of the carrier gas. Also, in the method for purifying peptidic anhydride disclosed in the specification of US Patent No. 3053854 (1962), a hydrocarbon group selected from naphthalene and o-xylene is subjected to gas phase and molecular oxygen in the presence of a vanadium catalyst. A process to obtain a gaseous effluent containing peptidic anhydride and molecular oxygen by reaction. In terms of improvement measures, it is proposed to include: let the obtained gaseous effluent be in a group of 150 ~ 450 ° C and selected from cobalt and manganese. A process for contacting a catalyst, a process for cooling the contacted gaseous effluent, and a technology for concentrating a substantially pure peptide anhydride from the cooled gaseous effluent. However, because these technologies require new equipment such as heat exchangers, they are reducing the construction cost of manufacturing equipment. Based on the consideration of factory equipment configuration, these equipments can be easily introduced into existing factories, and the reaction itself can be used to suppress the production of phthalide and so on. There is no room for improvement in aspects such as the effective production of peptidic acid. 6 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) (Please read the precautions on the back before filling this page)
593304 A7 ____ _B7 ____ 五、發明說明 【發明所欲解決之課題】 本發明有鑑於上述現狀而完成，其目的在於提供一種 酸酐之製造方法，其藉由多管式固定床反應器使得芳香族 化合物做接觸氣相氧化來製造酸酐時，因能夠減少成爲製 品品質惡化原因之副產物而提升所需酸酐之產率，並因能 夠以簡便方法設置副產物處理觸媒，乃能減低建造成本、 提高引進現有工廠之容易性。 【用以解決課題之手段】 本發明者等對藉由多管式固定床反應器使得芳香族化 合物做接觸氣相氧化以製造酸酐之方法進行各種探討時， 注意到使用經控制溫度之原料的90%以上可被消耗之第1 觸媒層(主觸媒層)及接續該第1觸媒層之第2觸媒層(副產 物處理觸媒層），在第1觸媒層進行接觸氣相氧化反應，在 第2觸媒層則將第1觸媒層排出之殘餘原料與中間體轉化 爲酸酐且燃燒副產物時，即使導入第2觸媒層之反應氣體 溫度與第1觸媒層之溫度相同，亦即與第1觸媒層之控制 溫度大約相同之溫度進行第2觸媒層之反應，仍可不減低 酸酐產率而抑制副產物生成。另外發現若於第2觸媒層所 充塡之觸媒活性小於第1觸媒層最後部之觸媒活性時，會g 夠抑制第1觸媒層生成之酸酐的燃燒而能以良好效率燃燒 副產物，如此即可圓滿解決上述課題而完成本發明。由於 此製造方法不需控制導入第2觸媒層之氣體溫度亦不需分 別控制第1觸媒層與第2觸媒層之溫度，故不需新設熱交 換器等而能減低製造裝置之建造成本、容易引進現有工廠 7 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） (請先閱讀背面之注意事項再填寫本頁)593304 A7 ____ _B7 ____ 5. Description of the invention [Problems to be solved by the invention] The present invention has been completed in view of the above-mentioned current situation, and the purpose thereof is to provide a method for producing an acid anhydride, which uses a multi-tubular fixed bed reactor to make aromatic compounds When contact gas-phase oxidation is used to produce acid anhydride, it can reduce the by-products that cause the deterioration of product quality and increase the yield of the required acid anhydride. Because it can set up by-product treatment catalysts in a simple way, it can reduce construction costs and increase Ease of introducing existing plants. [Means to solve the problem] When the present inventors conducted various discussions on a method for producing an acid anhydride by contacting an aromatic compound with gas phase oxidation by a multi-tubular fixed-bed reactor, they noticed that 90% or more of the first catalyst layer (main catalyst layer) which can be consumed and the second catalyst layer (by-product processing catalyst layer) following the first catalyst layer are contacted with gas in the first catalyst layer Phase oxidation reaction, in the second catalyst layer, when the remaining raw materials and intermediates discharged from the first catalyst layer are converted into acid anhydride and combustion by-products, even if the reaction gas temperature of the second catalyst layer is introduced into the first catalyst layer The temperature of the second catalyst layer is the same as that of the first catalyst layer, and the reaction of the second catalyst layer can still prevent the formation of by-products without reducing the yield of acid anhydride. In addition, it was found that if the catalyst activity charged in the second catalyst layer is less than the catalyst activity in the last part of the first catalyst layer, it will be able to suppress the combustion of the acid anhydride generated in the first catalyst layer and burn at a good efficiency. By-products can thus satisfactorily solve the above problems and complete the present invention. Since this manufacturing method does not need to control the temperature of the gas introduced into the second catalyst layer, nor does it need to control the temperatures of the first catalyst layer and the second catalyst layer separately, it is possible to reduce the construction of manufacturing equipment without the need for a new heat exchanger. Cost, easy to introduce existing factories 7 This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) (Please read the precautions on the back before filling this page)
593304 A7 _____B7 _ 五、發明說明（f) 。再者因不需爲減少副產物而提高接觸氣相氧化之際的反 應溫度，故能抑制觸媒劣化並提高酸酐之平均產率。 (請先閱讀背面之注意事項再填寫本頁) 本發明之酸酐製造方法包含：以必須使用多管式固定 床反應器之反應裝置來對含芳香族化合物之原料進行接觸 氣相氧化之製程(以下簡稱爲接觸氣相氧化製程）。使用於 此種接觸氣相氧化製程之原料亦可含有芳香族化合物以外 之1種或2種以上成分，但亦可不含，例如芳香族化合物 對100重量％原料之重量比例較佳爲95重量％以上。爲98 重量％以上則更好。 於上述接觸氣相氧化製程中，必須使用多管式固定床 反應器之反應裝置係受到溫度控制，且具有將原料之90% 以上加以消耗之第1觸媒層、及位於該第1觸媒層之後之 第2觸媒層。 上述弟1觸媒層爲方香族化合物進彳了接觸氣相氧化之 主觸媒層。於該第1觸媒層中芳香族化合物被接觸氣相氧 化生成酸酐，但此時通常也發生反應中間體與副產物。 上述第2觸媒層係以使得通過第1觸媒層之氣體中所 含未反應（殘餘）原料及中間體轉化爲酸酐並燃燒副產物爲 目的而設置之副產物處理觸媒層。藉由設置此副產物處理 觸媒層，則主觸媒層不需提高接觸氣相氧化之反應溫度仍 能減少酸酐中之副產物量，故能抑制因高溫引起之觸媒劣 化並提高酸酐之平均產率。又所謂平均產率指不交換觸媒 層進行製造時所生成之酸酐相對於全使用原料之比例。 上述第1觸媒層與第2觸媒層有由單層形成之形態， 8 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） " _ 593304 A7 ___B7_____ 五、發明說明（L ) -------------^裝—— (請先閱讀背面之注意事項再填寫本頁) 即觸媒層充塡1種觸媒之形態，亦有由複數層形成之形態 ，即觸媒層充塡2種以上觸媒之形態，但第1觸媒層以由 複數層形成之形態較好。此時在第1觸媒層中之複數層觸 媒層以先接觸原料之觸媒層活性較高於後接觸原料之觸媒 層較好。依此可抑制副產物生成及有效提升酸酐產率。又 第2觸媒層以由單層形成之形態較好。 上述第1觸媒層之溫度控制方法並無特別限定，例如 通常第1觸媒層設置於多管式固定床反應器之反應管內， 此時以鹽浴方法控制溫度較好。又第1觸媒層與第2觸媒 層之大小亦無特別限制，只要適合進行接觸氣相氧化製程 即可。 _線 上述接觸氣相氧化製程係以於第1觸媒層可消耗90% 以上原料的方式來適當設定所使用之觸媒種類及反應溫度 等反應條件。所謂消耗90 %以上原料意指裝入1〇0重量％ 原料中之90重量％因反應而被消耗。如消耗90重量％以下 時有因反應效率低而減低所需酸酐產率之虞。較佳爲94重 量％以上。 導入上述第2觸媒層之氣体溫度爲上述第1觸媒層控 制溫度之95%以上之溫度，且所充塡之觸媒活性小於上述 第1觸媒層最後部之觸媒活性。 導入上述第2觸媒層之氣体溫度爲上述第1觸媒層控 制溫度之95%以上之溫度，意指如上述第1觸媒層之控制 溫度爲100%時，溫度爲其95%以上之氣體導入上述第2 觸媒層。導入上述第2觸媒層之氣体溫度以上述第1觸媒 9 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） " ~ 593304 A7 ___Β7 _ 五、發明說明（7 ) 層控制溫度之98%以上之溫度較好。更佳爲上述第1觸媒 層控制溫度以上之溫度、即100%以上之溫度。如使得第2 觸媒層以與主觸媒層大約相同之溫度進行反應時，即不需 要以冷卻等控制導入第2觸媒層之氣体溫度，亦不需要分 別控制第1觸媒層與第2觸媒層之溫度。 上述第2觸媒層充塡之觸媒活性小於上述第1觸媒層 最後部之觸媒活性，意指上述第1觸媒層如由單層形成時 ，第2觸媒層所充塡之觸媒活性小於第1觸媒層所充塡之 觸媒活性；而上述第1觸媒層如由複數層形成時，第2觸 媒層所充塡之觸媒活性小於第1觸媒層最後部所充塡之觸 媒活性。如此在第2觸媒層使用較第1觸媒層最後部之觸 媒活性爲小、即低活性觸媒時，可抑制在第1觸媒層所生 成之所需酸酐之燃燒並有效燃燒副產物。以具體數値表示 第2觸媒層所充塡之觸媒活性小於第1觸媒層最後部所充 塡之觸媒活性時，第1觸媒層最後部之觸媒活性如爲100% ，則第2觸媒層之觸媒活性以50〜1〇〇%較好，60〜80%更 好。又於本說明書所謂活性意指原料通過相同量觸媒時之 原料轉化率。 上述第1觸媒層之設置形態通常爲設置於上述多管式 固定床反應器所具有之反應管內之形態。亦即在上述多管 式固定床反應器所具有反應管內充塡觸媒而成爲第1觸媒 層。又上述第2觸媒層之設置形態並無特別限制，如多管 式固定床反應器所具有反應管長度較長時，則可同第1觸 媒層般採用在反應管內充塡第2觸媒層所用之觸媒之形態 10 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297 [餐)~" (請先閱讀背面之注意事項再填寫本頁)593304 A7 _____B7 _ 5. Description of the invention (f). Furthermore, since it is not necessary to increase the reaction temperature at the time of contact with the gas phase oxidation in order to reduce by-products, it is possible to suppress the deterioration of the catalyst and increase the average yield of the acid anhydride. (Please read the precautions on the back before filling this page) The method for producing acid anhydride of the present invention includes a process of contacting gas-phase oxidation of raw materials containing aromatic compounds by a reaction device that must use a multi-tube fixed bed reactor ( Hereinafter referred to as the contact gas phase oxidation process). The raw materials used in such a contact gas-phase oxidation process may contain one or two or more components other than aromatic compounds, but may not contain them. For example, the weight ratio of aromatic compounds to 100% by weight of the raw materials is preferably 95% by weight. the above. It is more preferably 98% by weight or more. In the above-mentioned contact gas phase oxidation process, the reaction device that must use a multi-tubular fixed-bed reactor is temperature controlled, and has a first catalyst layer that consumes more than 90% of the raw material, and is located on the first catalyst. The second catalyst layer after the layer. The above-mentioned catalyst layer is the main catalyst layer of the fragrant compound which has been exposed to gas phase oxidation. In this first catalyst layer, the aromatic compound is oxidized by contact with the gas phase to generate an acid anhydride. However, in this case, reaction intermediates and by-products usually also occur. The second catalyst layer is a by-product treatment catalyst layer provided for the purpose of converting unreacted (residual) raw materials and intermediates contained in the gas passing through the first catalyst layer into acid anhydride and burning by-products. By setting this by-product to treat the catalyst layer, the main catalyst layer can reduce the amount of by-products in the acid anhydride without increasing the reaction temperature of the gas phase oxidation, so it can suppress the catalyst degradation due to high temperature and increase the acid anhydride. Average yield. The so-called average yield refers to the ratio of the acid anhydride produced during the manufacturing process without exchanging the catalyst layer to the raw materials used. The first catalyst layer and the second catalyst layer above are formed by a single layer. 8 paper sizes are applicable to China National Standard (CNS) A4 specifications (210 X 297 mm) " _ 593304 A7 ___B7_____ V. Description of the invention (L) ------------- ^ 装 —— (Please read the precautions on the back before filling in this page) The catalyst layer is filled with 1 type of catalyst. The layer is formed in a form in which the catalyst layer is filled with two or more catalysts, but the first catalyst layer is preferably formed in a form of a plurality of layers. In this case, the catalyst layers in the first catalyst layer are more active in the catalyst layer that contacts the raw material first than the catalyst layer that contacts the raw material later. According to this, the generation of by-products can be suppressed and the anhydride yield can be effectively improved. The second catalyst layer is preferably formed as a single layer. The temperature control method of the first catalyst layer is not particularly limited. For example, the first catalyst layer is usually provided in a reaction tube of a multi-tube fixed-bed reactor. In this case, it is better to control the temperature by a salt bath method. The sizes of the first catalyst layer and the second catalyst layer are not particularly limited, as long as they are suitable for the contact gas phase oxidation process. _Line The above-mentioned contact gas phase oxidation process is to appropriately set the reaction conditions such as the type of catalyst used and the reaction temperature so that more than 90% of the raw materials can be consumed in the first catalyst layer. The consumption of 90% or more of the raw materials means that 90% by weight of the 100% by weight of the raw materials are consumed due to the reaction. If it is consumed at 90% by weight or less, there is a possibility that the required acid anhydride yield may be reduced due to the low reaction efficiency. It is preferably at least 94% by weight. The temperature of the gas introduced into the second catalyst layer is at least 95% of the control temperature of the first catalyst layer, and the charged catalyst activity is lower than that of the last part of the first catalyst layer. The temperature of the gas introduced into the second catalyst layer is 95% or more of the control temperature of the first catalyst layer, which means that when the control temperature of the first catalyst layer is 100%, the temperature is 95% or more. The gas is introduced into the second catalyst layer. The temperature of the gas introduced into the second catalyst layer is the same as the first catalyst 9 above. The paper size is in accordance with China National Standard (CNS) A4 (210 X 297 mm) " ~ 593304 A7 ___ Β7 _ V. Description of the invention (7) Temperatures above 98% of the layer control temperature are preferred. More preferably, the temperature is equal to or higher than the first catalyst layer control temperature, that is, the temperature is equal to or higher than 100%. If the second catalyst layer is caused to react at about the same temperature as the main catalyst layer, it is not necessary to control the temperature of the gas introduced into the second catalyst layer by cooling or the like, and it is not necessary to control the first catalyst layer and the first catalyst layer separately. 2 The temperature of the catalyst layer. The catalyst activity charged by the second catalyst layer is smaller than the catalyst activity of the last portion of the first catalyst layer, which means that when the first catalyst layer is formed of a single layer, the The catalyst activity is less than the catalyst activity charged by the first catalyst layer; and when the first catalyst layer is formed by a plurality of layers, the catalyst activity charged by the second catalyst layer is less than the last of the first catalyst layer. The catalytic activity of the charge. In this way, when the catalyst activity in the second catalyst layer is lower than that of the catalyst in the last part of the first catalyst layer, that is, a low-activity catalyst, the combustion of the desired acid anhydride generated in the first catalyst layer can be suppressed and the byproducts can be effectively burned product. When the specific catalyst is used to indicate that the catalyst activity charged in the second catalyst layer is smaller than the catalyst activity charged in the last portion of the first catalyst layer, the catalyst activity in the last portion of the first catalyst layer is 100%, The catalyst activity of the second catalyst layer is preferably 50 to 100%, and more preferably 60 to 80%. The term "activity" as used in this specification means the raw material conversion rate when the raw material passes the same amount of catalyst. The installation form of the first catalyst layer is usually a form provided in the reaction tube of the multi-tube fixed bed reactor. That is, a catalyst is filled in the reaction tube included in the multi-tubular fixed-bed reactor to form a first catalyst layer. The configuration of the second catalyst layer is not particularly limited. If the length of the reaction tube in the multi-tube fixed bed reactor is long, the second catalyst layer can be filled in the reaction tube like the first catalyst layer. The form of the catalyst used in the catalyst layer 10 This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 [meal] ~) (Please read the precautions on the back before filling this page)
593304 A7 _____B7_ 五、發明說明（(f ) 。此時上述第1觸媒層與上述第2觸媒層設置於上述多管 式固定床反應器所具有之同一反應管內；爲充分發揮本發 明之作用效果，此種形態爲本發明之較佳形態之1種。 設置於現有工廠等時，如多管式固定床反應器所具有 反應管長度不足則第2觸媒層可設置於該反應管外。此時 上述第1觸媒層設置於上述多管式固定床反應器所具有反 應管內，而上述第2觸媒層設置於具有上述第1觸媒層之 反應管後部且爲絕熱之空間中較佳。此種形態可舉例如（1) 在設置第1觸媒層之多管式固定床反應器之反應管出口部 之集合空間部設置第2觸媒層之形態；（2)在由具有第1觸 媒層之多管式固定床反應器至反應氣體冷卻益或吸收器寺 之管路中設置第2觸媒層之形態。 上述（1)之形態爲上述第1觸媒層設置於上述多管式固 定床反應器所具有反應管內，而上述第2觸媒層設置於具 有上述第1觸媒層之反應管後方且爲絕熱之空間中之形態 ;爲充分發揮本發明之作用效果，此種形態爲本發明之較 佳形態之1種。 設置上述第2觸媒層之觸媒設置部可控制或不控制溫 度，但觸媒層溫度最好保持爲不致極端減低之狀態；在多 管式固定床反應器所具有反應管外設置第2觸媒層時，觸 媒設置部及到達觸媒設置部之管路最好絕熱使第2觸媒層 進行絕熱性反應。依此方法容易保持對第2觸媒層導入之 氣體溫度與第1觸媒層之控制溫度大約相同程度。 於本發明之必須使用多管式固定床反應器之反應裝置 11 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） (請先閱讀背面之注意事項再填寫本頁) 1^·- -線 593304 A7 _____Β7____ 五、發明說明（1 ) (請先閱讀背面之注音？事項再填寫本頁) 中，其第1觸媒層與第2觸媒層之設置形態係參照顯示必 須使用多管式固定床反應器之反應裝置截面示意圖之圖1 〜3說明之。於此等圖中，第1觸媒層由多層形成’第2 觸媒層則由單層形成。此等情形均設定爲第2觸媒層之觸 媒活性小於第1觸媒層最後部之觸媒活性。 圖1顯示第1觸媒層1及第2觸媒層2位於多管式固 定床反應器3並設置於同一反應管4中。 圖2顯示第1觸媒層1及第2觸媒層2位於多管式固 定床反應器3，但第1觸媒層1設置於反應管4中’而第2 觸媒層2設置於反應管4之後部且絕熱之空間部。 圖3顯示第1觸媒層1設置於多管式固定床反應器3 之反應管4中，而第2觸媒層2設置於多管式固定床反應 器3以外之反應器6。此時自多管式固定床反應器3至反 應器6之管路及反應器6最好均予以絕熱。 另一方面，圖4顯示習用接觸氣相氧化方法所採用之 必須使用多管式固定床反應器之反應裝置之一形態之截面 示意圖。第1觸媒層7係設置於多管式固定床反應器9之 反應管10中，第2觸媒層8設置於自多管式固定床反應器 9經由冷卻器12所連接之反應器13內。於該圖，第1觸 媒層7由複數層形成，第2觸媒層8則由單層形成，而由 多管式固定床反應器9供給反應器13之氣體溫度被冷卻器 12冷卻至相當低。具體而言爲第1觸媒層7控制溫度之 95%以下溫度。此時，可藉由提高第2觸媒層8之活性並 減低導入氣體溫度以抑制副產物生成量並產生酸酐，但因 12 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 593304 A7 ____B7___ 五、發明說明（ίϋ ) 需要設置冷卻器12,故不能減低建造成本亦不易引進現有 工廠設備中。 ----I---------· I I (請先閱讀背面之注意事項再填寫本頁) 相對於此，本發明可簡單應用於使用多管式反應器之 藉由接觸氣相氧化來製造酸酐之方法，例如應用於由鄰二 甲苯等鄰二烷基苯或萘製造肽酸酐、由苯製造馬來酸酐、 由硬炔等四烷基苯或由2,4,5-三甲基苯醛等三烷基苯醛製 造均苯四甲酸酐等時均能發揮減少副產物生成之效果。 線 於本發明，第1觸媒層充塡之觸媒(主觸媒)並無特別 限制，可使用通常藉由多管式固定床反應器使得芳香族化 合物做接觸氣相氧化來製造酸酐之方法中所使用之觸媒。 例如在將鄰二甲苯等鄰二烷基苯或萘加以氧化來製造肽酸 酐之觸媒方面可使用以氧化釩或氧化鈦爲主成分之觸媒活 性物質擔載於鈍性載體之觸媒等，可舉例如特公昭47-15323號公報、特公昭49-41036號公報、特公昭52-4538 號、特公昭47-5661號、特公昭49-89694號、特公昭57-105241號、特開平11-178788號等記載之觸媒。又亦可如 特願平1 1-178788號所記載般，將觸媒層分割爲多段，將 不同之觸媒組合使用。 上述主觸媒之較佳形態爲含五氧化釩(V205)，比表面 積10〜60m2/g之銳鈦礦型二氧化鈦(Ti02)，含有擇自鈮、 磷、銻、鈉、鉀、鉋、铷、钍等所構成群中之至少1種元 素所成之觸媒活性物質擔載於鈍性載體後，於500〜600°C 溫度及空氣流通下進行2〜10小時燒成所形成之觸媒。 由苯製造馬來酸酐之觸媒可使用以氧化釩或氧化鉬爲 13 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 593304 A7 ___ _ B7 J ' 1 丨丨 _ ---------- |·| 五、發明說明（t|) (請先閱讀背面之注咅？事項再填寫本頁) 主成分之觸媒活性物質擔載於鈍性載體而成之觸媒，此種 觸媒廣爲所知，可舉例如特公昭62-78號公報、特公平7一 16612號公報等記載之觸媒。又如特公平7-16612號所記 載’可將觸媒層分割爲多段，將不同之觸媒組合使用。 上述主觸媒之較佳形態爲釩、鉬、鈉、磷之氧化物， 及含有擇自鉀、絶、铷、鎂、鈣、緦、鋇、铈、銀、鈷、 銘、鉍等所構成群中之至少1種元素等之觸媒活性物質擔 載於鈍性載體後，於300〜600°C溫度及空氣流通下進行2 〜1〇小時燒成所形成之觸媒。 又以硬炔等四烷基苯或2,4,5-三甲基苯醛等三烷基苯 醛爲原料來製造均苯四甲酸酐所使用之觸媒，可舉例特公 昭45-4978號公報、特公昭45-15018號公報、特公昭45-15252號公報、特公昭47-38431號公報、特公昭49-31972 號公報、特公昭49-31973號公報、特公昭48-35251號公 報、特開平1-294679號公報、特公昭45-4978號公報、特 開平7-2864號公報、特開平7-171393號公報、特開 2000-1484號公報等記載之觸媒。又亦可如特開2000-1484 號公報所記載般，將觸媒層分割爲多段將不同之觸媒組合 使用。 上述主觸媒之較佳形態爲五氧化釩(V205)，二氧化鈦 (Ti02)，及擇自鈮、磷、銻、硼、鹼金屬、鹼土類金屬、 稀土類、锆、鉬、鎢、錫、銀、硫、钍等所構成群中之至 少1種元素之觸媒活性物質擔載於鈍性載體後，於300〜 650°C溫度及空氣流通下進行2〜10小诗燒成所形成之觸媒 14 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 593304 A7 五、發明說明（jl) Ο 本發明所使用第2觸媒層所充塡之觸媒’只要其活性 小於上述第1觸媒層最後部之觸媒則無特別限制，可使用 對上述第1觸媒層充塡之觸媒之構成元素組成比例、觸媒 活性物質擔載於鈍性載體之量、及燒成條件等改變以減小 活性之觸媒。例如製造酞酸酐之際之觸媒活性物質以含五 氧化釩(v205)、比表面積10〜60m2/g之銳鈦礦型二氧化鈦 (Ti〇2)、及鹼金屬較好，並可再含擇自銻、磷、鈮等所構 成群中之至少1種元素。此觸媒活性成分擔載於鈍性載體 後，於500〜650°C溫度及空氣流通下進行2〜10小時燒成 所形成之觸媒較好。觸媒組成以觸媒100重量份含五氧化 釩(V2〇5)l〜2〇重量份、二氧化鈦(Ti〇2) 99〜80重量份， 並對此2種成分合計100重量份進一部含鹼金屬換算爲其 氧化物〇·〇5〜2重量份、及擇自銻、磷、鈮所構成群中至 少1種元素換算爲其氧化物0·01〜5重量份較好。 本發明之鈍性載體以能夠在充分高於觸媒燒成溫度及 製造酸酐之際之反應溫度的溫度下長時間保持安定且不與 觸媒活性物質引起反應者較適合。此種鈍性載體可使用碳 化矽(SiC)、塊滑石、謹青石、氧化鋁、氧化锆、氧化鈦等 。其中以氧化鋁(AU〇3)含量20重量％以下(最好5重量％以 下），表觀氣孔率10%以上(最好15〜45%)之碳化矽載體等 適合使用。而更好之載體爲使得純度98%以上之碳化矽粉 進行自燒結所得之碳化矽載體。鈍性載體之形狀並無特別 限制，如球狀、顆粒狀、筒狀、環狀等均可，其平均粒徑 15 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公f * - (請先閱讀背面之注意事項再填寫本頁) -線 593304 A7 __ B7___ 五、發明說明（丨)） 以約2〜15mm較好，3〜12mm更好。 (請先閱讀背面之注意事項再填寫本頁) 將上述觸媒活性物質擔載於鈍性載體之方法亦無特別 限制，將一定量鈍性載體裝入可由外部加熱之旋轉筒，保 持於100〜300°C下令含觸媒活性物質之液狀物(漿料)噴霧 ，使得鈍性載體擔載觸媒活性物質之方法較爲簡便而適合 。此時觸媒活性物質對鈍性載體之擔載量隨使用鈍性載體 之大小及形狀而異，如爲球狀或筒狀以3〜30g活性物質/ 100mL鈍性載體之比例較好，而以5〜20g活性物質/ 100mL鈍性載體更好。 以下就使用上述觸媒使鄰二甲苯及/或萘與分子狀氧或 含分子狀氧之氣體進行接觸氣相氧化以行酞酸酐反應之較 佳形態說明之。 線 上述第1觸媒層係使用在內徑15〜40mm、最好15〜 27mm之管內塡充高度1.5〜4m、最好2〜3.5m之觸媒所得 之反應管。多管式固定床反應器中之熱介質維持300〜400 °C、最好330〜38(TC溫度；將含鄰二甲苯及/或萘之原料 與空氣或含10〜21體積％分子狀氧之氣體同時導入反應管 ，以70g原料/Nm3以上之氣體濃度使含分子狀氧之氣體 以 1000〜6000hf_1(STP :標準狀態）、最好 1500〜4000hr一1 (STP)之空間速度流動。 上述第2觸媒層最好使用在內徑15mm以上之空間內 充塡觸媒所得者。其觸媒量最好爲主觸媒層充塡觸媒量之 5〜40重量％，而10〜30重量％更好。 如此形成第1觸媒層與第2觸媒層，且設定反應條件 16 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 593304 A7 ____ B7___ 五、發明說明（ff) 進行本發明之酸酐製造方法時，能夠充分發揮其作用效果 Ο (請先閱讀背面之注意事項再填寫本頁) 【實施例】 以下用實施例詳細說明本發明，但本發明不受此等實 施例之限制。 實施例1 (調製觸媒） 混合鈦鐵礦與80%濃硫酸，充分反應後用水稀釋得硫 酸鈦水溶液。加鐵片於此水溶液當做還原劑，將鈦鐵礦中 鐵成分還原爲亞鐵離子後冷卻，以硫酸亞鐵的形式析出分 離。吹入加熱爲150°C之水蒸氣於如上製得之硫酸鈦水溶 液，使含水氧化鈦沈澱。此沈澱經水洗、酸洗、及二次水 洗後，於800°C之溫度及空氣流通下燒成4小時。此燒成 物以噴射氣流進行粉碎處理，得平均粒徑0.5/zm、比表面 積22m2 / g之銳鈦礦型氧化鈦。 溶解草酸250g於去離子水6400mL得草酸水溶液，對 此加偏釩酸銨l2l_86g、硫酸絶18.85g、三氧化銻45.55g ，並充分攪拌。隨後取該氧化鈦2000g加入上述所得之溶 液中，用乳化機攪拌調製得觸媒漿液。 將表觀氣孔率35%、純度98.5重量％、外徑7mm、內 徑3.5mm、長7mm之圓筒狀碳化矽（SiC)自燒結載體 2000mL裝入可由外部加熱之直徑35cm、長80cm不銹鋼 製旋轉爐中，待預熱成200〜250°C後一面使爐旋轉一面將 該觸媒漿液噴於載體上，使得觸媒活性物質以8.0g/mL載 17 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） " ' 593304 A7 ___B7___ 五、發明說明（[f ) (/ 體之比例被擔載。隨後在空氣流通下以570°C燒成6小時 。將此當作第2觸媒。 (反應） 主觸媒層使用在第1反應器己實際使用3年之觸媒。 其後端設置可調整溫度之第2反應器並充塡上述第2觸媒 。第1反應器由內徑25mm、長3.2m反應管所構成，備有 鹽浴冷卻設備。第2反應器則由內徑55mm反應管所構成 。第2反應器觸媒量爲第1反應器觸媒量之15%。第1反 應器之反應條件爲將空間速度2475hr_1、氣體濃度100g( 鄰二甲苯）/ INm3(空氣)之氣體導入。第1反應器鹽浴溫度 355°C、第2反應器鹽浴溫度355°C時，第1反應器出口處 之鄰二甲苯轉化率爲約100%。第2反應器出口處之肽酸酐 產率爲111重量％、苯酞產率爲O.lmol%。 第2觸媒層充塡之觸媒及主觸媒層最後部觸媒之活性 ，以鄰二甲苯爲原料時之轉化率評估。SV = 3400 hi-1、負 載70g / INm3、SBT = 350°C時，第1反應器最後部觸媒之 轉化率爲100%、第2反應器觸媒之轉化率爲70%。 實施例2 如同實施例1，但不設置第2反應器，而是將第2反 應器所使用之第2觸媒充塡於第1反應器主觸媒層最後部 觸媒之更下游側。第1反應器之反應條件爲將空間速度 2150hf—1、氣體濃度100g(鄰二甲苯）/ INm3(空氣）之氣體 導入。第1反應器鹽浴溫度355°C時，第1反應器出口處 之酞酸酐產率爲111重量％、苯肽產率爲O.lmol%。 18 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） (請先閱讀背面之注意事項再填寫本頁) ，裝 線· 593304 A7 ____B7___ 五、發明說明（U) 比較例1 (請先閱讀背面之注意事項再填寫本頁) 如同實施例1，但不設置第2反應器，其他均與實施 例1相同條件進行反應。 第1反應器出口處之肽酸酐產率爲111重量％、苯肽 產率爲0.2mol%。 比較例2 如同實施例1，但不設置第2反應器，且鹽浴溫度設 定爲369°C以外，其他均與實施例1相同條件進行反應。 第1反應器出口處之酞酸酐產率爲109重量％、苯酞產率 爲 O.lmol% 〇 如以上實施例所示，將第2觸媒使用於第2反應器或 第1反應器最後部相較於不使用第2觸媒，可減少副產物 苯肽之生成，同時與習用提高反應溫度以減少苯酞之方法 比較時，可確認在肽酸酐產率方面佔優勢。 【發明效果】 本發明由上述之構成形成，可減少成爲製品品質惡化 原因之副產物，可提升所需酸酐之產率，並可用簡便方法 設置副產物處理觸媒，故能夠減低建造成本，且提高引進 現有工廠之容易性。同時可抑制高溫引起之觸媒劣化。 【圖式之簡單說明】 圖1係本發明之製造方法所使用之必須使用多管式固 定床反應器之反應裝置之一形態，顯示第1觸媒層與第2 觸媒層設置於多管式固定床反應器之同一反應管內之截面 示意圖。 19 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 593304 A7 ____B7 ___ 五、發明說明（1) 圖2係本發明之製造方法所使用之必須使用多管式固 定床反應器之反應裝置之一形態，顯示第1觸媒層設置於 多管式固定床反應器之反應管內，而第2觸媒層設置於反 應管後部且絕熱之空間部之截面示意圖。 圖3係本發明之製造方法所使用之必須使用多管式固 定床反應器之反應裝置之一形態，顯示第1觸媒層設置於 多管式固定床反應器之反應管內，而第2觸媒層設置於多 管式固定床反應器以外且絕熱之反應器之空間部之截面示 意圖。 圖4係顯示習用接觸氣相氧化方法所使用之必須使用 多管式固定床反應器之反應裝置之一形態之截面示意圖。 【符號說明】 1、7 第1觸媒層(主觸媒層) 2、8 第2觸媒層 3、9 多管式固定床反應器 4、10 反應管 5、11 熱介質 6、13 反應器 12 冷卻器 20 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） (請先閱讀背面之注意事項再填寫本頁)593304 A7 _____B7_ 5. Explanation of the invention ((f). At this time, the first catalyst layer and the second catalyst layer are disposed in the same reaction tube of the multi-tube fixed bed reactor; in order to fully utilize the present invention, For the effect, this form is one of the preferred forms of the present invention. When installed in an existing plant, etc., if the length of the reaction tube in the multi-tube fixed-bed reactor is insufficient, the second catalyst layer can be installed in the reaction. Outside the tube. At this time, the first catalyst layer is disposed inside the reaction tube of the multi-tube fixed-bed reactor, and the second catalyst layer is disposed at the rear of the reaction tube having the first catalyst layer and is thermally insulated. This form is preferred. For example, (1) a form in which a second catalyst layer is provided in a collection space portion of an outlet portion of a reaction tube of a multi-tube fixed bed reactor provided with a first catalyst layer; (2) ) A form in which a second catalyst layer is provided in a pipeline from a multi-tube fixed bed reactor having a first catalyst layer to a reaction gas cooling reactor or absorber temple. The form of the above (1) is the first catalyst The medium layer is arranged in the reaction of the above multi-tube fixed bed reactor. Inside the tube, and the second catalyst layer is disposed behind the reaction tube having the first catalyst layer and is in a thermally insulated space; in order to give full play to the effects of the present invention, this form is the best of the present invention The type of the catalyst is 1. The catalyst setting part for setting the second catalyst layer may control or not control the temperature, but the temperature of the catalyst layer is preferably kept in a state that does not decrease extremely; the reaction in the multi-tube fixed bed reactor has When the second catalyst layer is installed outside the pipe, it is preferable that the catalyst setting part and the pipeline reaching the catalyst setting part be insulated to make the second catalyst layer perform an adiabatic reaction. In this way, it is easy to maintain the introduction of the second catalyst layer. The gas temperature is about the same as the control temperature of the first catalyst layer. In the present invention, a multi-tubular fixed-bed reactor must be used. 11 The paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) ) (Please read the notes on the back before filling this page) 1 ^ ·--Line 593304 A7 _____ Β7 ____ V. Description of the invention (1) (Please read the note on the back? Matters before filling this page), the first touch Design of the media layer and the second catalyst layer The configuration is described with reference to Figures 1 to 3 showing the schematic cross-section of the reaction device of a multi-tubular fixed-bed reactor. In these figures, the first catalyst layer is formed from multiple layers, and the second catalyst layer is formed from a single layer. In these cases, the catalyst activity of the second catalyst layer is set to be lower than the catalyst activity of the last part of the first catalyst layer. Figure 1 shows that the first catalyst layer 1 and the second catalyst layer 2 are located in multiple tubes. Type fixed bed reactor 3 is arranged in the same reaction tube 4. Fig. 2 shows that the first catalyst layer 1 and the second catalyst layer 2 are located in the multi-tube fixed bed reactor 3, but the first catalyst layer 1 is provided in In the reaction tube 4, the second catalyst layer 2 is provided at the rear of the reaction tube 4 and is a thermally insulated space portion. Fig. 3 shows that the first catalyst layer 1 is provided in the reaction tube 4 of the multi-tube fixed bed reactor 3. The second catalyst layer 2 is provided in a reactor 6 other than the multitubular fixed bed reactor 3. At this time, the pipes from the multitubular fixed bed reactor 3 to the reactor 6 and the reactor 6 are preferably insulated. On the other hand, Fig. 4 is a schematic cross-sectional view showing one form of a reaction device that requires a multi-tubular fixed-bed reactor used in the conventional contact gas phase oxidation method. The first catalyst layer 7 is provided in the reaction tube 10 of the multi-tube fixed-bed reactor 9, and the second catalyst layer 8 is provided in the reactor 13 connected to the multi-tube fixed-bed reactor 9 via the cooler 12 Inside. In this figure, the first catalyst layer 7 is formed by a plurality of layers, the second catalyst layer 8 is formed by a single layer, and the temperature of the gas supplied to the reactor 13 from the multi-tube fixed bed reactor 9 is cooled by the cooler 12 to Quite low. Specifically, the temperature is 95% or less of the control temperature of the first catalyst layer 7. At this time, by increasing the activity of the second catalyst layer 8 and reducing the temperature of the introduced gas, the amount of by-products generated and acid anhydride can be suppressed, but because of the 12 paper sizes, the Chinese National Standard (CNS) A4 specification (210 X 297) (%) 593304 A7 ____B7___ 5. Description of the Invention (ί) It is necessary to install a cooler 12, so it cannot reduce the construction cost and it is not easy to introduce it into existing plant equipment. ---- I --------- · II (Please read the notes on the back before filling this page) In contrast, the present invention can be easily applied to the use of multi-tubular reactors by contacting gas Method for producing acid anhydride by phase oxidation, for example, applied to o-dialkylbenzene such as o-xylene or naphthalene, peptidic anhydride, maleic anhydride from benzene, tetraalkylbenzene such as hard acetylene, or 2,4,5- When trialkylbenzaldehyde such as trimethylbenzaldehyde is used to produce pyromellitic anhydride, etc., the effect of reducing by-product formation can be exerted. In the present invention, the catalyst (main catalyst) filled with the first catalyst layer is not particularly limited, and an aromatic compound can be produced by contacting an aromatic compound with gas phase oxidation by a multitubular fixed bed reactor. The catalyst used in the method. For example, catalysts for producing peptidic anhydride by oxidizing o-dialkylbenzene or naphthalene, such as o-xylene, can use a catalyst having a vanadium oxide or a titanium oxide as a main component and a catalyst supported on a blunt carrier. For example, Japanese Patent Publication No. 47-15323, Japanese Patent Publication No. 49-41036, Japanese Patent Publication No. 52-4538, Japanese Patent Publication No. 47-5661, Japanese Patent Publication No. 49-89694, Japanese Patent Publication No. 57-105241, Japanese Patent Publication No. Hokkai The catalyst described in No. 11-178788. Alternatively, as described in Japanese Patent Application No. 1 1-178788, the catalyst layer can be divided into multiple sections, and different catalysts can be used in combination. The preferred form of the above main catalyst is anatase titanium dioxide (Ti02) containing vanadium pentoxide (V205) and a specific surface area of 10-60 m2 / g, containing niobium, phosphorus, antimony, sodium, potassium, planer, thorium A catalyst active substance made of at least one element in the group consisting of sulfonium, osmium, etc. is supported on a blunt carrier, and the catalyst formed by firing at a temperature of 500 to 600 ° C and air circulation for 2 to 10 hours . The catalyst for maleic anhydride made from benzene can use vanadium oxide or molybdenum oxide as the standard. The paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) 593304 A7 ___ _ B7 J '1 丨 丨-- --------- | · | V. Description of the invention (t |) (Please read the note on the back? Matters before filling out this page) The catalytic active substance of the main component is carried on a blunt carrier Such catalysts are widely known, and examples thereof include catalysts described in Japanese Patent Publication No. 62-78 and Japanese Patent Publication No. 7-16612. Another example, as described in JP No. 7-16612, is to split the catalyst layer into multiple segments and use different catalysts in combination. The preferred form of the above main catalyst is composed of oxides of vanadium, molybdenum, sodium, phosphorus, and containing selected from potassium, absolute, thorium, magnesium, calcium, thorium, barium, cerium, silver, cobalt, indium, and bismuth A catalyst active substance such as at least one element in the group is supported on a blunt carrier, and then the catalyst formed is calcined at a temperature of 300 to 600 ° C and air circulation for 2 to 10 hours. The catalyst used in the production of pyromellitic anhydride using tetraalkylbenzenes such as hard alkyne or trialkylbenzaldehyde such as 2,4,5-trimethylbenzaldehyde can be exemplified by JP 45-4978. Gazette, Japanese Patent Publication No. 45-15018, Japanese Patent Publication No. 45-15252, Japanese Patent Publication No. 47-38431, Japanese Patent Publication No. 49-31972, Japanese Patent Publication No. 49-31973, Japanese Patent Publication No. 48-35251, Catalysts described in JP-A No. 1-294679, JP-A No. 45-4978, JP-A No. 7-2864, JP-A No. 7-171393, and JP-A No. 2000-1484. Alternatively, as described in Japanese Patent Application Laid-Open No. 2000-1484, the catalyst layer may be divided into a plurality of sections, and different catalysts may be used in combination. The preferred forms of the above main catalysts are vanadium pentoxide (V205), titanium dioxide (Ti02), and selected from niobium, phosphorus, antimony, boron, alkali metals, alkaline earth metals, rare earths, zirconium, molybdenum, tungsten, tin, The catalyst active substance of at least one element in the group consisting of silver, sulfur, thorium, etc. is supported on a blunt carrier, and is formed by firing 2 to 10 poems at a temperature of 300 to 650 ° C and air circulation. Catalyst 14 This paper size is in accordance with Chinese National Standard (CNS) A4 (210 X 297 mm) 593304 A7 5. Description of the invention (jl) 〇 The catalyst filled with the second catalyst layer used in the present invention is only required The catalyst whose activity is less than the last part of the first catalyst layer is not particularly limited, and the composition ratio of the constituent elements of the catalyst filled with the first catalyst layer can be used, and the amount of the catalyst active material supported on the blunt carrier , And firing conditions to change the catalyst. For example, the active material used in the production of phthalic anhydride is preferably anatase titanium dioxide (Ti〇2) containing vanadium pentoxide (v205), specific surface area of 10 ~ 60m2 / g, and alkali metals. At least one element from the group consisting of antimony, phosphorus, and niobium. After the catalyst active ingredient is supported on a blunt carrier, the catalyst formed by firing at a temperature of 500 to 650 ° C and air circulation for 2 to 10 hours is preferred. The catalyst composition consists of 100 parts by weight of the catalyst containing 1 to 20 parts by weight of vanadium pentoxide (V205) and 99 to 80 parts by weight of titanium dioxide (Ti〇2), and a total of 100 parts by weight of these two ingredients are included in one part. The alkali metal conversion is preferably 0.05 to 2 parts by weight of its oxide, and at least one element selected from the group consisting of antimony, phosphorus, and niobium is preferably converted to 0.01 to 5 parts by weight of its oxide. The inert carrier of the present invention is suitable for those who can maintain stability for a long time at a temperature sufficiently higher than the catalyst firing temperature and the reaction temperature during the production of acid anhydride, without causing a reaction with the catalyst active material. Examples of such a passive carrier include silicon carbide (SiC), talc, laplite, alumina, zirconia, and titanium oxide. Among them, a silicon carbide carrier having an alumina (AU03) content of 20% by weight or less (preferably 5% by weight or less) and an apparent porosity of 10% or more (preferably 15 to 45%) is suitable for use. A better carrier is a silicon carbide carrier obtained by self-sintering silicon carbide powder having a purity of more than 98%. The shape of the blunt carrier is not particularly limited, such as spherical, granular, cylindrical, annular, etc., and its average particle size is 15. This paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 male f * -(Please read the precautions on the back before filling this page) -Line 593304 A7 __ B7___ V. Description of the invention (丨)) It is better to be about 2 ~ 15mm, and more preferably 3 ~ 12mm. (Please read the precautions on the back before filling this page.) There is no particular limitation on the method for supporting the above-mentioned catalyst active substance on a blunt carrier. A certain amount of the blunt carrier is placed in a rotating cylinder that can be heated externally and kept at 100 ~ 300 ° C The liquid substance (slurry) containing the catalyst active substance is sprayed, so that the method of supporting the catalyst active substance with a blunt carrier is simple and suitable. At this time, the load of the catalyst active substance on the inert carrier varies with the size and shape of the inert carrier. For a spherical or cylindrical shape, the ratio of 3 ~ 30g active substance / 100mL inert carrier is better, and It is better to use 5 ~ 20g active substance / 100mL inactive carrier. The following is a description of a preferred form of using the above-mentioned catalyst to contact o-xylene and / or naphthalene with molecular oxygen or a gas containing molecular oxygen to perform gas phase oxidation for phthalic anhydride reaction. Wire The above-mentioned first catalyst layer is a reaction tube obtained by filling a catalyst having a height of 1.5 to 4 m, and preferably 2 to 3.5 m in a tube having an inner diameter of 15 to 40 mm, preferably 15 to 27 mm. The heat medium in the multitubular fixed-bed reactor is maintained at 300 ~ 400 ° C, preferably 330 ~ 38 (TC temperature; the raw materials containing o-xylene and / or naphthalene and air or containing 10 to 21% by volume of molecular oxygen The gas is simultaneously introduced into the reaction tube, and the molecular oxygen-containing gas flows at a space velocity of 1000 to 6000 hf_1 (STP: standard state), preferably 1500 to 4000 hr-1 (STP) at a gas concentration of 70 g of raw material / Nm3 or more. The second catalyst layer is preferably obtained by filling the catalyst in a space with an inner diameter of 15 mm or more. The catalyst amount is preferably 5 to 40% by weight of the main catalyst layer, and 10 to 30%. The weight percent is better. The first catalyst layer and the second catalyst layer are formed in this way, and the reaction conditions are set. 16 The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 593304 A7 ____ B7___ V. Invention Explanation (ff) When carrying out the method for producing the anhydride of the present invention, it can give full play to its effect. 0 (Please read the precautions on the back before filling out this page.) [Examples] The following examples will be used to describe the present invention in detail, but the present invention is not Limited by these embodiments. Embodiment 1 (Modulation (Medium) Mix ilmenite with 80% concentrated sulfuric acid. After fully reacting, dilute with water to obtain a titanium sulfate aqueous solution. Add iron flakes to this aqueous solution as a reducing agent, reduce the iron component in ilmenite to ferrous ions, and then cool. The form of iron precipitates and separates. Water vapor heated at 150 ° C is blown into the titanium sulfate aqueous solution prepared above to precipitate the aqueous titanium oxide. The precipitate is washed with water, pickled, and washed with water at 800 ° C. It is fired for 4 hours under temperature and air circulation. This fired product is pulverized by a jet stream to obtain anatase titanium oxide having an average particle diameter of 0.5 / zm and a specific surface area of 22 m2 / g. 250 g of oxalic acid was dissolved in 6400 mL of deionized water. An oxalic acid aqueous solution was obtained, and 121-86 g of ammonium metavanadate, 18.85 g of sulfuric acid, and 45.55 g of antimony trioxide were added to the solution, followed by sufficient stirring. Subsequently, 2000 g of the titanium oxide was added to the solution obtained above, and stirred to prepare a catalyst slurry with an emulsifier. A cylindrical silicon carbide (SiC) with an apparent porosity of 35%, a purity of 98.5% by weight, an outer diameter of 7mm, an inner diameter of 3.5mm, and a length of 7mm was sintered from a 2,000 mL sintered carrier into a 35cm-diameter, 80cm-long stainless steel that can be heated externally. system In the converter, after the catalyst is preheated to 200 ~ 250 ° C, the catalyst slurry is sprayed on the carrier while the furnace is rotated, so that the catalyst active substance is loaded at 8.0g / mL. The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) " '593304 A7 ___B7___ V. Description of the invention ([f) (/ body ratio is carried. It is then fired at 570 ° C for 6 hours under air circulation.) Take this as the second catalyst. (Reaction) The main catalyst layer uses the catalyst that has been used in the first reactor for 3 years. The second reactor is equipped with a second reactor capable of adjusting temperature and filled with the second catalyst. The first reactor was composed of a reaction tube with an inner diameter of 25 mm and a length of 3.2 m, and was equipped with a salt bath cooling device. The second reactor consists of a 55mm inner diameter reaction tube. The amount of catalyst in the second reactor is 15% of the amount of catalyst in the first reactor. The reaction conditions of the first reactor were the introduction of a gas at a space velocity of 2475hr_1 and a gas concentration of 100g (o-xylene) / INm3 (air). When the temperature of the salt bath in the first reactor was 355 ° C and the temperature of the salt bath in the second reactor was 355 ° C, the conversion of o-xylene at the outlet of the first reactor was about 100%. The yield of peptidic anhydride at the exit of the second reactor was 111% by weight, and the yield of phthalide was 0.1 mol%. The activity of the catalyst filled in the second catalyst layer and the activity of the catalyst in the last part of the main catalyst layer were evaluated by using o-xylene as the raw material. When SV = 3400 hi-1, load 70g / INm3, and SBT = 350 ° C, the conversion rate of the catalyst in the last part of the first reactor is 100%, and the conversion rate of the catalyst in the second reactor is 70%. Example 2 is the same as Example 1, except that the second reactor is not provided, but the second catalyst used in the second reactor is charged on the downstream side of the catalyst in the last part of the main catalyst layer of the first reactor. The reaction condition of the first reactor is to introduce a gas having a space velocity of 2150hf-1 and a gas concentration of 100g (o-xylene) / INm3 (air). When the temperature of the salt bath in the first reactor was 355 ° C, the yield of phthalic anhydride at the exit of the first reactor was 111% by weight, and the yield of phenyl peptide was 0.1 mol%. 18 This paper size is in accordance with Chinese National Standard (CNS) A4 (210 X 297 mm) (Please read the precautions on the back before filling this page). Assembly line · 593304 A7 ____B7___ 5. Description of the invention (U) Comparative Example 1 (Please read the precautions on the back before filling in this page.) As in Example 1, except that the second reactor is not provided, the rest are reacted under the same conditions as in Example 1. The yield of peptidic anhydride at the exit of the first reactor was 111% by weight, and the yield of phenylpeptide was 0.2mol%. Comparative Example 2 The same reaction as in Example 1 was performed except that the second reactor was not provided and the temperature of the salt bath was set to 369 ° C. The yield of phthalic anhydride at the exit of the first reactor was 109% by weight and the yield of phthalphthalein was 0.1 mol%. As shown in the above example, the second catalyst was used at the end of the second reactor or the first reactor Compared with not using the second catalyst, it can reduce the production of phenyl peptide as a by-product, and compared with the conventional method of increasing the reaction temperature to reduce phthalide, it can be confirmed that it has an advantage in the yield of peptide anhydride. [Effects of the invention] The present invention is formed by the above-mentioned structure, which can reduce by-products that cause the deterioration of product quality, can improve the yield of the required acid anhydride, and can set up by-product processing catalysts in a simple method, so that it can reduce construction costs, and Improve the ease of introducing existing plants. At the same time, catalyst degradation caused by high temperatures can be suppressed. [Brief description of the drawings] FIG. 1 is a form of a reaction device that must use a multi-tube fixed-bed reactor used in the manufacturing method of the present invention, showing that the first catalyst layer and the second catalyst layer are provided in multiple tubes. Schematic cross-section of the same reaction tube of a fixed-bed reactor. 19 This paper size is in accordance with Chinese National Standard (CNS) A4 (210 X 297 mm) 593304 A7 ____B7 ___ V. Description of the invention (1) Figure 2 is a multi-tubular fixed-bed reaction used in the manufacturing method of the present invention One form of the reaction device of the reactor is a schematic cross-sectional view showing that the first catalyst layer is disposed in the reaction tube of the multi-tube fixed-bed reactor, and the second catalyst layer is disposed at the rear of the reaction tube and in the insulated space portion. FIG. 3 is a form of a reaction device that must use a multi-tubular fixed-bed reactor used in the manufacturing method of the present invention, showing that the first catalyst layer is disposed in the reaction tube of the multi-tubular fixed-bed reactor, and the second The catalyst layer is a schematic cross-sectional view of a space portion of an adiabatic reactor which is provided outside the multi-tube fixed-bed reactor. Fig. 4 is a schematic cross-sectional view showing one form of a reaction device that must use a multi-tubular fixed-bed reactor used in the conventional contact gas phase oxidation method. [Symbol description] 1, 7 First catalyst layer (main catalyst layer) 2, 8 Second catalyst layer 3, 9 Multi-tube fixed bed reactor 4, 10 Reaction tube 5, 11 Heat medium 6, 13 Reaction Cooler 12 Cooler 20 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) (Please read the precautions on the back before filling this page)