1225479 A7 B7 五、發明説明〇 相關青案 相關之美國專利申請案第09/481，811號係於2000年1月12 日才疋出申清；相關之美國專利申請案第〇9/757,458號係於 2001年1月1〇日提出申請。 1明背上 本I明係關於藉相關先質於適當溶劑中之催化性液相氧 化反應而製造羧酸或其酯之改良法。更特定言之，本發明 疋用於對-二甲苯製得對-苯二甲酸之催化性液相氧化反應的 ，良法，其包含下列連續步驟：於高壓下，將反應物餵至 第個氧化反應區中，其中，控制溫度和氧的消耗，且形 成的任何對-苯二甲酸留在溶液中，之後，將所得反應介質 餵至第二個氧化反應區以完成氧化反應。 商業規模實施上，所有的對_苯二甲酸係藉對-二甲苯的催 化f生液相艾氣氧化反應製得。商業法使用醋酸作爲溶劑， 以多價重金屬或金屬作爲觸媒。鈷和錳是最常用的重金屬 觸媒，溴作爲方法中之自由基的可更新來源。 醋酸、空氣（分子態的氧）、對-二甲苯和觸媒連續餵至維 持於175至225 c和1000至3000 kPa (即，10-30大氣壓）的氧 化反應器中。進料醋酸··對_二曱苯比基本上低於5 ··丨。空 氣添加量超過將對-二甲苯完全轉化成對-苯二曱酸所須的化 學計量，以儘可能減少所不欲副產物（如：有色形成物）之形 成。此氧化反應是放熱反應，藉由使得醋酸溶劑蒸發而移 除熱。相關蒸汽冷凝，大部分的冷凝液迴餾至反應器，排 出一些冷凝液以控制反應器水濃度（每莫耳反應的對-二曱笨 -4 - 本紙張尺度適用中國國家標準(CNS) A4規格(210 X 297公釐) 12254791225479 A7 B7 V. Description of the invention 0 US Patent Application No. 09 / 481,811 related to the related green case was filed on January 12, 2000; related US Patent Application No. 09 / 757,458 The application was made on January 10, 2001. 1 On the back This I is an improved method for producing a carboxylic acid or an ester thereof by a catalytic liquid-phase oxidation reaction of a related precursor in an appropriate solvent. More specifically, the present invention is a good method for the catalytic liquid-phase oxidation reaction of p-xylene to p-phthalic acid, which comprises the following continuous steps: feeding the reactants to the first oxidation under high pressure In the reaction zone, wherein the temperature and the consumption of oxygen are controlled, and any terephthalic acid formed is left in the solution, after that, the obtained reaction medium is fed to a second oxidation reaction zone to complete the oxidation reaction. On a commercial scale implementation, all terephthalic acid is produced by the oxidation reaction of p-xylene to the liquid phase moxa gas. Commercial methods use acetic acid as the solvent and polyvalent heavy metals or metals as the catalyst. Cobalt and manganese are the most commonly used heavy metal catalysts, and bromine is a renewable source of free radicals in the process. Acetic acid, air (molecular oxygen), p-xylene, and the catalyst were continuously fed to the oxidation reactor maintained at 175 to 225 c and 1000 to 3000 kPa (that is, 10-30 atmospheres). The feed acetic acid ...- p-dibenzobenzene ratio is substantially lower than 5 ... The amount of air added exceeds the stoichiometry required to completely convert p-xylene to p-phthalic acid to minimize the formation of unwanted by-products (such as colored formations). This oxidation reaction is exothermic and removes heat by allowing the acetic acid solvent to evaporate. Relevant steam condensation, most of the condensate is back distilled to the reactor, and some condensate is discharged to control the water concentration of the reactor (per-mole reaction pair-Erfangben-4-This paper is in accordance with Chinese National Standard (CNS) A4 Specifications (210 X 297 mm) 1225479
反應形成兩莫耳水)。停留時間基本上是3〇分鐘至2小時， 此視万法而足。視氧化反應器操作條件（如：溫度、觸 度和停留時間）而定地，有時溶劑和先質大量分解，此朴 咼方法的操作成本。 < 氧化反應斋的流出物g π物（即，反應產物）是粗製對_苯二甲 (ΤΑ)晶體漿狀物，藉過滹，、、主 ' 送至儲存處。之後將它們引至個別純化㈣中或將它們導 至聚合法中。雖，然亦有對·甲苯甲搭和對_曱苯甲酸及所不二 的有色形成物存在，粗製ΤΑ的主要雜質是4_羧基苯甲趁& CBA) ’其爲氧化不完全的對_二甲苯。藉由以下文中更詳細 説明的方式進行根據本發明之氧化反應，能更實質上減少 最終ΤΑ產物中的雜質之形成並有效控制溶劑和先質分解。 發明概述 本發明是一種用於對-二甲苯製得對_苯二甲酸之催化性液 相氧化反應的改良法，其包含下列連續步驟：於高壓下， 將包括適當溶劑的反應物餵至第一個氧化反應區中，其中 ’控制溫度和氧的消耗，且形成的任何對-苯二甲酸留在溶 液中’之後，將所得反應介質餵至第二個氧化反應區。此 方法包含：The reaction forms two moles of water). The residence time is basically 30 minutes to 2 hours, depending on the method. Depending on the operating conditions of the oxidation reactor (such as temperature, touch, and residence time), sometimes the solvent and precursors are decomposed in large amounts, which is the operating cost of this simple method. < The effluent g π of the oxidation reaction (that is, the reaction product) is a crude para-xylylene (TA) crystal slurry, which is sent to the storage site through 滹, 主, and 主. They are then introduced into individual purified mash or introduced into a polymerization process. Although, there are also p-toluene and p-benzoic acid and the same colored formation, the main impurity of the crude TA is 4-carboxybenzyl, which is an incompletely oxidized pair. _Xylene. By carrying out the oxidation reaction according to the present invention in a manner described in more detail below, the formation of impurities in the final TA product can be substantially reduced and the solvent and precursor decomposition can be effectively controlled. SUMMARY OF THE INVENTION The present invention is an improved process for the catalytic liquid-phase oxidation of p-xylene to terephthalic acid, which comprises the following sequential steps: feeding a reactant including a suitable solvent to a In one oxidation reaction zone, after 'controlling temperature and oxygen consumption, and any terephthalic acid formed remains in solution', the resulting reaction medium is fed to a second oxidation reaction zone. This method contains:
裝 訂Binding
線 (a) 於至少約2,000 kPa高至10,000或更高的壓力範圍内 ’形成包含溶劑和氧化反應觸媒的進料流； (b) 連續和同時將（1)進料流，（2)對-二甲苯和（3)供應的 氧引至第一個反應區而形成反應介質，其中，溶劑：對-二 甲苯質量比範圍由10-25 : 1 ; -5- 本紙張尺度適用中國國家標準(CNS) A4規格(210X 297公釐) 1225479 A7 _______B7__ 五、發明説明（3 ) (C)將在第一個反應區中的反應介質的氧消耗量限制於 將對-二甲苯完全轉化成對-苯二甲酸所須氧量的50%以下·， 及 (d)將反應介質引至第二個反應區並同時將反應介質的 壓力降低至l，200 kPa至2,0〇〇kPa範圍内。 可以藉任何便利方式自離開第二個反應區的反應介質中 回收所得的對·苯二甲酸。 本發明中描述用以將對_二甲苯轉化成對-苯二甲酸的改良 氧化系統，應瞭解本發明可以藉由相關先質於適當溶劑中 足催化性液相氧化反應而用以製造羧酸或其酯，特別是對_ 苯二甲酸或其酯。基於發現到：在至少兩個階段或區域中 進行氧化反應，能夠實質上改善先質轉化成其相關羧酸之 ^ ;兄’藉此完成本發明，其中的至少兩個階段包含： (1) 於至少約2, 〇〇〇 kPa提南壓力下，形成包含溶劑 和氧化觸媒的進料流，之後連續並同時將進料流、先質和 供應的氧引至高壓第一個反應區中，以形成反應介質，其 中’落劑：先質質量比亦相當高，即，在10-25 : 1範圍内 ’但就經濟和操作性觀點，較佳範圍是丨〇_2〇 : 1 ;和 (2) 將來自第一個反應區的反應介質引至第二個反 應區中，於此使氧化反應完全。 維持所述溶劑：先質質量比以外，第一個反應區中的氧 消耗限制於使先質完全轉化成其相關羧酸或酯所須氧量的 5 0%以下。視先質而定，其可具有一、二、三或更多個酸基 。藉下列方法中的一或多者控制第一個反應區中的氧消耗 -6- 本紙張尺度適用中國國家標準(CNS) A4規格(210 x 297公董了 1225479 A7 B7 五、發明説明（4 ) :(0使氧供應（即，氧濃度）維持在預定範圍内；（ii)使觸 媒濃度維持在預定範圍内；（iii)將在第一個反應區中的停 留時間（定義爲反應器液體體積除以反應器進料速率）限制低 於約6分鐘，以低於4分鐘爲佳；及（iv)視情況地自反應區 移除熱，以使離開第一個反應區的反應介質溫度維持低於 約 210〇C。 將反應介質引至第二個反應器中的同時，將反應介質壓 力降至1，200 kPa至2,000 kPa範圍内。可藉慣用方法自最終 反應介質（基本上是酸晶體漿狀物）回收形成的叛酸。 根據本發明的較佳實施例，氧直接溶入包含溶劑和氧化 反應觸媒的進料中，之後，含氧的進料流和先質連續同時 引至第一個氧化反應區中，其爲塞狀流動反應區。進入第 一個反應區之後，先質（如：對_二甲苯）立刻與含氧溶劑充 分混合以啓動反應。藉由控制氧供應、觸媒濃度、在第一 個反應區中的停留時間和/或溫度，能夠將反應介質内的氧 消耗値控制（即，限制）在將先質完全轉化成其相關羧酸所須 氧的50%以下。之後將此反應介質引至前述第二個（更慣用 的）反應器中。 / 本發明之方法特別可用以藉對-二甲苯於包含醋酸和水的 落劑中之催化性液相氧化反應製備對-苯二甲酸。 附圖簡诚_ 附圖1是根據本發明之方法的一個實施例的簡圖。 附圖2是根據本發明之方法的一個較佳實施例的簡圖。 附圖3是附圖2所示程序圖之變通法的簡圖，其中，所示 -7- 冢紙張尺度適财國g家標準(CNS) M規格(21QX 297公董) ------ A7 B7 多、發明説明（5 ) 者是逆混合反應器。 發明詳述 本發明在於發現到：在醋酸溶劑存在時，進行對-二甲苯 I液相催化性氧化反應，有效率地以商業規模分段地在第 一個高壓反應區進行氧化反應，之後進入第二個更慣用的 反應區，藉此實質上改善方法效能和產物品質。 方法的第一個反應區之特徵在於溶劑：先質質量比相當 高，由10-25 : 1或更高（如下面的一個實施例中詳細描述者） 且壓力相當高，如：在至少2，_ kPa高至1〇，_ kpa範圍内 或更咼。可以使用較高的溶劑··先質質量比，如：高至 :1或更高，但對-二甲苯通過由經由第一個反應區餵至程 序中時，觀察到第一個反應區中的溶劑：先質質量比在 20: 1範圍内時，總程序可得最佳結果。視情況地冷卻第_ 個反應區，以將離開第一個反應區的反應介質溫度控制在 低於約2HTC。控制溫度、觸媒濃度、反應器停留時間和/或 使進入第一個反應區的氧供料維持在預定範圍内，使其能 夠便利地將反應介質的氧消耗量限制於將對_二甲苯完全轉 化成對-冬一甲自艾所須氧量的5 0 %以下。 例如，藉由將内部冷卻線圈或其他冷卻裝置置於第一個 反應區中，藉由以冷卻護套環繞反應器或者藉由使反應介 質循環通過位於反應器外的熱交換機而達到溫度控制的目 的。 藉由將一些含觸媒的母液繞過第一個反應區地引至第二 個反應區中而建立觸媒控制效果。 -8 - 本紙張尺度適用中國國家標準(CNS) A4規格(21〇 X 297公釐) 1225479 A7 __B7 五、發明説明（6 ) 嚴格要求防止固態T A沉積在第一個反應區的任何冷卻表 面上。藉由限制氧消耗而限制TA形成，亦藉由維持反應介 質中的高溶劑：先質比來防止TA沉積，並藉由選擇適當冷 卻劑（如：沸水）和冷卻裝置來避免在反應介質中的任何位置 形成冷點。 離開第一個反應區時，在其進入更慣用的氧化反應器中 時，同時降低反應介質的壓力。此反應器基本上是，如·· 攪掉槽反應器或氣泡管反應器。可以藉由使反應介質通過 位於反應器周邊的一或多個壓力下降閥而便利地達到調降 壓力的目的。反應介質在進入第二個反應器之後迅速分散 時，可達最佳結果。使用已知之用以將含對-二甲苯的進料 分散於慣用反應器中的方法可達迅速分散的目的。例如， 在攪拌槽反應器中，此包括將反應介質注入反應器中之低 於液體線並接近揽掉葉輪卸料處。在氣泡管柱型反應器中 ’可以藉由將反應介質注入接近空氣進料處而使其迅速分 散。 現參考附圖，附圖1是根據本發明之方法的一個實施例之 簡化圖。如前述者，以關於對-苯二甲酸之產製描述此方法 ’但本發明可用以產製多種羧酸或其酯和它們的混合物。 藉由先形成包含溶劑（如··醋酸和水）和氧化反應觸媒的進 料10而實施此方法。實施上，進料流含有包含（i)循環溶劑 、循環母液和觸媒之混合物，管線11，（ii)來自第二個反 應器的反應器冷凝物，管線12，和（iU)未使用過的醋酸補 充物，管線13。混合的進料流含有典型觸媒組份（如：c〇、 -9 - 本紙張尺度適用中國國家標準(CNS) A4規格(210X297公爱) 1225479 A7 B7 五 、發明説明（7 二使用單—慣用氧化反應器所用之-般稀釋濃度 二）?見情況地（但未示），使一些含觸媒的母液（管線u) =通人第二個反應器2G，以㈣第—個反應區中之觸媒 广成進料流的各組份溫度爲基礎，混合進料流溫度通 吊由130至ΐ60χ：。但未嚴格要求進料流的溫度。 進料流1〇的壓力因適當幫浦14而提高至至少約2,_心 ，但^常超過此値，之後，進料流與對-二甲苯（經由管線 ⑹和氧來源（經由管線17)連續並同時進入第一個擾掉槽反 應器15。 經由管線17供應的氧可以是空氣、富含氧的空氣、與惰 性氣體（如：二氧化碳）混合的氧或基本上是純氧。當氧來 源包括氮或其他惰性載氣時，以選擇在第一個反應區中的 ^卻程度及其操作壓力，使得存在於第一個反應區中的蒸 汽幾乎無燃料（即，蒸汽的烴含量低於低竣爆炸限制（咖)） 局佳。使用基本上{純氧者作爲氧來源肖，以選擇在第— 個反應區中的冷卻程度及其操作壓力，使得無蒸汽相存在 於第—個反應區中爲佳。視情況地（但未示於附圖it)，藉 由位於進料幫浦下游的混合裝置，一些氧可以預先溶入進 料10中。 •士甲豕進料16可視情況地事先與醋酸溶劑混合並引至 進料幫浦14上游或下游系統中。視情況地（但未示），一部份 對一甲苯進料16繞過反應器15且直接進入第二個反應器 。第-個反應g中得到的反應介質（未使任何對_二甲苯繞道 ' 10- 本紙張尺度適用中國國家標準(CNS) A4規格(210X297公擎) 1225479 A7 _ B7 五、發明説明（8 ) 進入第二個反應區）之醋酸··對-二甲笨比在1 q_25 : 1範圍内 。醋酸：對-二甲苯質量比由10-20 : 1時，此實施例觀察到 最佳結果。 一部分的對-二甲苯進料（即，附圖1中的管線丨6及附圖2和 3中的管線31)繞過第一個反應器並直接進入第二個反應器 2〇時，所得在第一個反應器中之反應介質中的溶劑：對-二 甲苯質量比會隨著繞過第一個反應器的對_二甲苯比例而提 南’所得質量比値南至1 〇 〇 : 1。此對-二甲苯進料（管線1 6) 在進入弟一個反應器之後應迅速分散。藉由用以使含對·二 曱苯的進料迅速分散於慣用反應器中的任何方法可達到此 目的。在攪:摔槽反應斋15中，如附圖1所示之本發明之實施 例，應包括將進料注入接近攪拌器葉輪排料處。雖然附圖1 舉出攪拌槽反應器，但使用其他慣用氧化反應器亦可得到 令人滿意的結果。 此方法於有氧化反應觸媒系統存在進行，此系統可爲均 相或非均相。通常使用均相觸媒並選自一或多種重金屬化 合物，如：始、獻和/或結化合物。此外，觸媒通常亦包括 氧化反應促進劑，如：溴。實施方法的期間内，觸媒金屬 和氧化反應促進劑大多留在溶液中，回收產物之後，回收 觸媒金屬和氧化反應促進劑並與補充用的新觸媒溶液再循 環利用。 第一個反應區的進料流（管線10)含有典型氧化反應觸媒組 份（如：Co、Mn、Br)，但觸媒濃度是自產物回收的循環母 液（管線1 1)的約1/5至1/3。之後，蒸發溶劑及自第二個反應 -11 - 本紙張尺度適用中國國家標準(CNS) A4規格(210X297公釐) 1225479 A7 _____B7 五、發明説明（9 ) 區20中的塔頂餾出物移除溶劑時，觸媒濃度提高至更慣用 的觸媒濃度。在第一個反應區中的觸媒金屬總濃度基本上 在^。至^⑼ppm (重量/重量）範圍内，而在第二個反應區 中的觸媒金屬濃度基本上在500至3,〇〇〇 ppm (重量/重量）範 圍内。使用Co和Μη金屬觸媒系統時，在第一個反應區中的 觸媒金屬總濃度應控制高於約25〇 ppm (重量/重量）爲佳， 以得到良好的觸媒選擇性和活性。 此氧化反應高度放熱。視氧消耗和溶劑比而定，在未使 用冷卻此反應器之裝置的情況下，反應熱會將第一種反應 介質的溫度提高至高於第二個反應器的操作溫度和/或高於 2抓。希望使第-個反應器出口溫度維持相當低溫，以儘 可能減少溶劑和先質分解（即，燃燒）及消除反應介質在進入 第二個反應區入口處之壓力降低時的溶劑閃蒸情況。第一 個反應區因此可以包括冷卻線圈18或使用一些用以移除反 應器（和反應介質）的熱的其他内部或外部裝置，以將反應介 質出口溫度控制低於2HTC，以低於第二個反應器操作溫度 爲佳。重要的是：冷卻劑溫度約12〇r或以上，以免形成冷 點及使得對-苯二甲酸（TA)局部沉澱。 使氧供應至第一個反應區的速率維持在預定範圍内並控 制出口溫度、觸媒濃度和反應介質的停留時間，使得操作 者能夠將反應介質中的氧消耗控制在將對-二曱苯完全峙化 成TA所須氧量的5〇%以下。因此，根據本發明，二二=二 反應器15中，對-二曱苯主要轉化成TA中間產物，如：對_ 甲苯甲趁、對-甲苯甲酸和4_CBA。前述條件和有效的出口 -12- 本紙張尺度適用中國國家標準(CNS) Μ規格(2i〇x297公爱)'~' ------- 1225479 A7 _____B7 五、發明説明（1。 ) 溫度控制下，第一個反應器不會製得任何固態τ A。 反應介質離開第一個反應器1 5，經由管線19進入第二個 反應器（即’氧化反應區）20，其如所示者，其可以是慣用連 續攪拌槽反應器。同時，反應介質壓力降至L20Q kPa至 2,000 kPa範圍内。如前述者，使反應介質通過位於反應器 20周圍的一或多個壓力下降閥或噴嘴2丨，能夠簡便地達到 降低壓力的目的，藉此，反應介質藉由注入位於反應器之 液fa管線下方的擅;掉葉輪區域而迅速分散。反應器2 〇的程 序條件（即，溫度、壓力、觸媒濃度和停留時間）在慣用範圍 内，但減少氧消耗以減低氧化反應強度。 來自第一個反應器15之包括氮或其他惰性載氣及使用過 的或過量空氣之進入第一個反應器的氧源（管線22)與新供應 的立氣或含氧氣體（管線22a)混合，引入所得混合進料氣流 並藉簡便裝置迅速分散於第二個反應器2〇的反應介質中。 或者，來自第一個反應器15之使用過的或過量的空氣可以 經由虛線22b引至所示冷凝器24中，額外之未使用過的空氣 或含氧氣體被引至第二個反應器2〇。 ΤA會在反應斋20中沉澱形成漿狀物，且可以使用慣用方 法經由管線23自反應器系統回收。來自反應器2〇的反應器 館頂路Ά應含有一些醋酸和水，其經由冷凝器2 4冷凝，大 部分的冷凝物經由管線12循環（即，再利用）用以補充第一個 反應态15的進料流。一部分醋酸和水冷凝液流（所謂導出的 水）轉至溶劑脱水系統以移除反應水。視情況地（但未示）， 一部分冷凝液可以回到反應器20，經由迴餾裝置進入反應 -13- 本紙張尺度適用中國國家標準(CNS) A4規格(210X297公釐) 1225479 A7 B7 五、發明説明（11 ) 器頂部空間和/或經由獨立進料管線或藉由與離開的進料流 (管線19)混合而進入反應區。 附圖2是本發明之較佳實施例的簡圖。根據此實施例的第 一個反應區（即，第一個反應器30)是塞狀流動反應器。此處 所謂的"塞狀流動反應器”定義爲拉長或管狀的反應區，其 中，反應物流過管或導管時會迅速和充份徑向混合。但本 發明不限於任何與塞狀流動反應區類似的反應器構造。 如附圖1中所示者，進料流10是混合進料流，包含循 環溶劑、循環母液和觸媒（經由管線1 1 )，（ii)第二個反應器 冷凝液（經由管線12)和（iii)未使過的醋酸補充物（經由管線 13)。視情況地（但未示），可以藉由使一些含觸媒的母液（管 線11)繞道進入第二個反應器20而控制在第一個反應區中的 觸媒濃度。此實施例中供應的氧（管線17a)基本上是純淨的 氣態氧。 混合進料流溫度通常由13CTC至160°C，此視補充用流體的 溫度而定。發現約140°C的溫度範圍内適用以引發氧化反 應。 藉任何適當的抽吸裝置14，混合進料1 〇的壓力提高至至 少（但通常超過）2,000 kPa。選用的壓力確保經管線na引入 之所有的氣態氧會在所示的第一個反應器3〇之前溶解於進 料流中。之後’有氧溶解於其中的混合進料流與經由管線 3 1銀入的對-二甲苯同時並連續進入塞狀流動反應器3〇，此 引發反應。對-二甲苯可以視情況地爲與醋酸溶劑之預混合 物且此混合物經由管線3丨餵入。如前述者，視情況地，一 -14 - 本紙張尺度適用中國國家標準(CNS) A4規格(210X297公爱) 1225479 A7 B7 五、發明説明（12 使用任何便利的連線混合$置33€|ι分子溶解於混合進 料流中，以使得混合進料流中的溶解氧濃度高至3 〇% (重量 /重量）。混合裝置33可以是用以將氧排至進料流中的連線噴 嘴。連線靜態混合器（未示）亦可以位個反應器3〇上游 處以利於混合。 部分對-二甲苯進料31可以繞過反應器3G而直接進入第二個 反應㈣。-部分對甲苯進料31進人I個反應器2〇時 ’所得在第—個反應器中之反應介質中的溶劑：對-二甲苯 質量比會因爲—部分對_二甲苯進料未進人第—個反應器而 提向，因此，所得質量比可達80:卜高至1〇〇: “戈更高。 根據本發明，亦可分批引入氧，即，於第一個反應區3〇 延線的多個位置引入氧。藉由分批注入氧，可降低局部最 高氧濃度，此亦降低反應器操作壓力。 貝際上，進料流1 〇和對-二甲苯同時且連續地進入塞狀流 動反應斋j 〇中，藉此形成反應介質，其中，所得溶劑：對_ 一甲苯比至少約10 : 1，但溶劑：對_二甲苯比可高至25 : i 或以上。較佳實施例中，溶劑··對_二甲苯比在丨〇_2〇 : 1範 圍内。 在塞狀流動反應區3 0中的停留時間相當短，即，不到6分 鐘0 附圖2所示反應器30是外殼和管設計。反應介質通過管， 而冷卻劑（如：壓縮水（PW))引至殼側中，水於此處沸騰並 以蒸汽形式（S)被移除。少量水滌氣（煮沸器放氣，BB)用以 控制水系統中累積的雜質/殘)、查。 -15- 本紙張尺度適用中國國家標準(CNS) A4規格(210X297公釐) 1225479 ----- 57___ 五、發明説明（13 ) 藉由k制製得水蒸汽的壓力及溫度而使離開第一個反應 备〇〇的反應介質溫度維持低於21(TC。如所述者，根據本發 明地控制程序參*，能夠將第一個反應區中的反應介質的 1消耗量控制在使對_二甲苯完全轉化成TA所須的氧之观 以下。因此，對-二甲苯基本上在第一個反應器30中轉化成 TA中間產物，如：對-甲苯甲醛、對-甲苯甲酸和4_CBa。 d述U和有政的出口溫度控制下，$ _個反應器3 〇不會 製得任何固態T A。 雖然附圖2所示者是殼和管反應器設計，反應器30可以是 任何具選用熱移除和選用多重氧注入裝置之適當的反應器 P又计”例如，反應洛可以是多重管，氧注入各管的反應介 質上游處。或者，可以使用逆混合反應器（如：抽吸的循環 込路反斋）’氧注入迴路中並自迴路移除熱，此如附圖3 所示者。反應器亦可包含一系列冷卻或未冷卻的槽，視情 況地將氧注入各槽的上游處。 如則述附圖1所示實施例所述者，離開塞狀流動第一個反 應备州的反應介質經由管線19進入第二個反應器（即，氧化 反應區）20 ’其如所示者，可以是慣用的連續攪掉槽反應器 。同時，反應介質壓力降至kpa至2,⑽〇 kpa範圍内。 可以藉由使反應介質通過位於反應器2〇周邊的一或多個壓 力下降閥或噴嘴2 1而便利地達到調降壓力的目的，於此處 ，藉由將反應介質注入反應器中之低於液體線並接近攪摔 葉輪區域中而使其迅速分散。反應器2〇的程序條件（即，溫 度壓力、觸媒纹度和停留時間）在慣用範圍内，但減少氧 -16 - 本紙張尺度適用中國國家標準(CNs) A4規格(210X297公釐） 1225479 A7 ___B7 五、發明説明（14 ) 消耗以減低氧化反應強度。 引入未使用過的空氣或含氧氣體進料（管線22a)並藉任何 簡便方式迅速分散於第二個反應器20中的反應介質中。 TA會在反應器20中沉澱形成漿狀物，且可以使用慣用方 法經由管線23自反應器系統回收。來自反應器2〇的反應器 餾頂瘵汽應含有一些醋酸和水，其經由冷凝器24冷凝，大 部分的冷凝物經由管線12循環（即，再利用）用以補充第一個 反應器3 0的進料流。一部分醋酸和水冷凝液流（所謂導出的 水）轉至溶劑脱水系統以移除反應水。視情況地（但未示）， 一部分冷凝液可以回到反應器20，經由迴餾裝置進入反應 器頂部空間和/或經由獨立進料管線或藉由與離開的進料流 (管線19)混合而進入反應區。 -17- 本紙張尺度適用中國國家標準(CNS) A4規格(210 X 297公釐)Line (a) 'forms a feed stream comprising a solvent and an oxidation reaction catalyst at a pressure range of at least about 2,000 kPa up to 10,000 or higher; (b) continuously and simultaneously (1) the feed stream, (2) Para-xylene and (3) supplied oxygen are led to the first reaction zone to form a reaction medium, wherein the mass ratio of solvent: para-xylene ranges from 10-25: 1; -5- This paper size applies to China Standard (CNS) A4 specification (210X 297 mm) 1225479 A7 _______B7__ V. Description of the invention (3) (C) Limit the oxygen consumption of the reaction medium in the first reaction zone to the complete conversion of p-xylene to Less than 50% of the amount of terephthalic acid required, and (d) introducing the reaction medium to the second reaction zone and simultaneously reducing the pressure of the reaction medium to the range of 1,200 kPa to 2,000 kPa Inside. The resulting terephthalic acid can be recovered by any convenient means from the reaction medium leaving the second reaction zone. The present invention describes an improved oxidation system for converting para-xylene to p-phthalic acid. It should be understood that the present invention can be used to produce carboxylic acids by using relevant precursors to catalyze liquid-phase oxidation reactions in appropriate solvents. Or its esters, especially terephthalic acid or its esters. Based on the finding that: performing the oxidation reaction in at least two stages or regions can substantially improve the conversion of the precursor into its related carboxylic acid; thereby completing the present invention, at least two of the stages include: (1) At a pressure of at least about 2,000 kPa, a feed stream containing a solvent and an oxidation catalyst is formed, and then the feed stream, precursor, and supplied oxygen are continuously and simultaneously introduced into a high-pressure first reaction zone To form a reaction medium, in which the 'falling agent: precursor mass ratio is also quite high, that is, in the range of 10-25: 1', but from the economic and operational point of view, the preferred range is 丨 〇_2〇: 1; And (2) introducing the reaction medium from the first reaction zone into the second reaction zone, where the oxidation reaction is completed. Maintaining the solvent: precursor mass ratio, the oxygen consumption in the first reaction zone is limited to less than 50% of the amount of oxygen required to completely convert the precursor into its associated carboxylic acid or ester. Depending on the precursor, it may have one, two, three or more acid groups. Use one or more of the following methods to control the oxygen consumption in the first reaction zone -6- This paper size applies the Chinese National Standard (CNS) A4 specification (210 x 297 public director 1225479 A7 B7 V. Description of the invention (4 ): (0 to maintain the oxygen supply (ie, oxygen concentration) within a predetermined range; (ii) to maintain the catalyst concentration within a predetermined range; (iii) the residence time in the first reaction zone (defined as the reaction The reactor liquid volume divided by the reactor feed rate) is limited to less than about 6 minutes, preferably less than 4 minutes; and (iv) optionally remove heat from the reaction zone to allow the reaction leaving the first reaction zone The temperature of the medium is maintained below about 210 ° C. While introducing the reaction medium into the second reactor, the pressure of the reaction medium is reduced to the range of 1,200 kPa to 2,000 kPa. The above is the acid crystal formed by the recovery of acid crystals. According to a preferred embodiment of the present invention, oxygen is directly dissolved in a feed containing a solvent and an oxidation reaction catalyst, and thereafter, the oxygen-containing feed stream and precursor Continuously and simultaneously led to the first oxidation reaction zone, which is Flow reaction zone. After entering the first reaction zone, the precursor (such as p-xylene) is immediately mixed with the oxygen-containing solvent to start the reaction. By controlling the oxygen supply, catalyst concentration, in the first reaction zone The residence time and / or temperature can control (ie, limit) the oxygen consumption in the reaction medium to less than 50% of the oxygen required to completely convert the precursor to its related carboxylic acid. This reaction medium is then introduced to In the aforementioned second (more customary) reactor. / The method of the present invention is particularly useful for the preparation of terephthalic acid by catalytic liquid-phase oxidation of p-xylene in a solvent containing acetic acid and water. Figure 1_ Figure 1 is a diagram of an embodiment of the method according to the present invention. Figure 2 is a diagram of a preferred embodiment of the method according to the present invention. Figure 3 is the program shown in Figure 2 A simplified diagram of the workaround shown in the figure, which shows the -7- mound paper standard suitable for financial countries (CNS) M specifications (21QX 297 public directors) ------ A7 B7, invention description (5) This is a reverse mixing reactor. DETAILED DESCRIPTION OF THE INVENTION The present invention consists in finding that: At this time, the liquid-phase catalytic oxidation reaction of p-xylene I was carried out, and the oxidation reaction was efficiently carried out on a commercial scale in the first high-pressure reaction zone, and then entered into the second more conventional reaction zone, thereby substantially Improve the method performance and product quality. The first reaction zone of the method is characterized by solvent: precursor mass ratio is quite high, from 10-25: 1 or higher (as described in detail in the following example) and pressure Quite high, such as: at least 2, kPa as high as 10, _ kpa or more. Higher solvents can be used. · Precursor mass ratio, such as: as high as: 1 or higher, but for- When xylene was fed into the program through the first reaction zone, it was observed that when the solvent: precursor mass ratio in the first reaction zone was within the range of 20: 1, the best results were obtained in the overall program. The _th reaction zone is optionally cooled to control the temperature of the reaction medium leaving the first reaction zone to below about 2 HTC. Controlling temperature, catalyst concentration, reactor residence time, and / or maintaining the oxygen feed to the first reaction zone within a predetermined range, making it convenient to limit the oxygen consumption of the reaction medium to para-xylene Completely converted to less than 50% of the amount of oxygen required for the pair-Dongyijia Ziyi. For example, temperature control can be achieved by placing an internal cooling coil or other cooling device in the first reaction zone, by surrounding the reactor with a cooling jacket, or by circulating the reaction medium through a heat exchanger located outside the reactor. purpose. The catalyst control effect is established by bypassing some of the catalyst-containing mother liquor into the second reaction zone, bypassing the first reaction zone. -8-This paper size is in accordance with Chinese National Standard (CNS) A4 specification (21〇X 297 mm) 1225479 A7 __B7 V. Description of the invention (6) Strict requirement to prevent solid TA from depositing on any cooling surface of the first reaction zone . Limit TA formation by limiting oxygen consumption, and also prevent TA deposition by maintaining a high solvent: precursor ratio in the reaction medium, and avoid being in the reaction medium by selecting an appropriate coolant (such as boiling water) and cooling equipment Forms a cold spot anywhere. When leaving the first reaction zone, as it enters the more conventional oxidation reactor, the pressure of the reaction medium is reduced at the same time. This reactor is basically, such as agitated tank reactor or bubble tube reactor. The pressure can be conveniently reduced by passing the reaction medium through one or more pressure reducing valves located around the reactor. Best results are obtained when the reaction medium is rapidly dispersed after entering the second reactor. The rapid dispersion can be achieved by using a method known to disperse a para-xylene-containing feed in a conventional reactor. For example, in a stirred tank reactor, this involves injecting the reaction medium below the liquid line in the reactor and approaching the impeller discharge. In a bubble column reactor, the reaction medium can be quickly dissipated by injecting the reaction medium close to the air feed. Referring now to the drawings, FIG. 1 is a simplified diagram of one embodiment of a method according to the present invention. As before, this method is described in terms of the production of terephthalic acid ', but the present invention can be used to produce a variety of carboxylic acids or their esters and mixtures thereof. This method is performed by first forming a feed 10 containing a solvent (such as acetic acid and water) and an oxidation reaction catalyst. In practice, the feed stream contains a mixture of (i) recycled solvent, recycled mother liquor, and catalyst, line 11, (ii) reactor condensate from the second reactor, line 12, and (iU) are unused The acetic acid supplement, line 13. The mixed feed stream contains typical catalyst components (such as: c0, -9-this paper size applies to Chinese National Standard (CNS) A4 specifications (210X297 public love) 1225479 A7 B7 V. Description of the invention (7 II. Use single — The usual dilution concentration used in conventional oxidation reactors 2)? See the situation (but not shown), so that some mother liquid containing catalyst (line u) = 2G of the second reactor, to the first reaction zone Based on the temperature of each component of the catalyst Guangcheng feed stream, the temperature of the mixed feed stream is from 130 to ΐ60χ :. However, the temperature of the feed stream is not strictly required. The pressure of the feed stream 10 is appropriate to help Pu14 and raised to at least about 2, _, but ^ often exceeds this threshold, after which the feed stream is continuously and simultaneously entered into the first disturbance with p-xylene (via line ⑹ and oxygen source (via line 17)). Tank reactor 15. The oxygen supplied through line 17 may be air, oxygen-enriched air, oxygen mixed with an inert gas (such as carbon dioxide), or substantially pure oxygen. When the source of oxygen includes nitrogen or other inert carrier gas To select the degree of operation in the first reaction zone and its operating pressure, The steam present in the first reaction zone is almost fuelless (ie, the hydrocarbon content of the steam is lower than the low end explosion limit (Ca)). It is better to use basically {pure oxygen as the oxygen source Xiao, in order to choose The degree of cooling in one reaction zone and its operating pressure make it possible for a non-steam phase to exist in the first reaction zone. As appropriate (but not shown in the figure it), by the downstream of the feed pump Mixing device, some oxygen can be dissolved in feed 10 in advance. • Shijiazhang feed 16 can optionally be mixed with acetic acid solvent in advance and led to the upstream or downstream system of feed pump 14. As appropriate (but not shown) ), A portion of the para-toluene feed 16 bypasses the reactor 15 and directly enters the second reactor. The reaction medium obtained in the first reaction g (without any para_xylene bypass' 10- this paper size Applicable to China National Standard (CNS) A4 specification (210X297 engine) 1225479 A7 _ B7 V. Description of the invention (8) Entering the second reaction zone) Acetic acid ·· -p-dimethylbenzene ratio is in the range of 1 q_25: 1. When the mass ratio of acetic acid: p-xylene is from 10-20: 1, this example observes Best results were obtained. A portion of the para-xylene feed (ie, line 6 in Figure 1 and line 31 in Figures 2 and 3) bypassed the first reactor and went directly to the second reactor. At 20:00, the obtained solvent in the reaction medium in the first reactor: the mass ratio of para-xylene will be raised as the ratio of para-xylene bypasses the first reactor, and the mass ratio of 所得 -nan is obtained. Up to 100: 1. This para-xylene feed (line 16) should be dispersed quickly after entering the reactor. By using it to quickly disperse the feed containing para-xylene in the conventional reactor Any of these methods can be used to achieve this. In the agitation: drop tank reaction box 15, the embodiment of the present invention as shown in FIG. 1 should include injecting the feed near the agitator impeller discharge. Although Figure 1 shows a stirred tank reactor, other conventional oxidation reactors can be used to obtain satisfactory results. This method is performed in the presence of an oxidation catalyst system, which can be homogeneous or heterogeneous. Homogeneous catalysts are usually used and are selected from one or more heavy metal compounds, such as starting, donating, and / or compounding compounds. In addition, catalysts often include oxidation promoters such as bromine. During the implementation of the method, most of the catalyst metal and the oxidation reaction accelerator remain in the solution. After the product is recovered, the catalyst metal and the oxidation reaction accelerator are recovered and recycled with the new catalyst solution for replenishment. The feed stream (line 10) of the first reaction zone contains typical oxidation reaction catalyst components (such as: Co, Mn, Br), but the catalyst concentration is about 1 of the recycled mother liquor (line 1 1) recovered from the product / 5 to 1/3. After that, the solvent was evaporated and from the second reaction -11-This paper size applies the Chinese National Standard (CNS) A4 specification (210X297 mm) 1225479 A7 _____B7 V. Description of the invention (9) The top distillate shift in zone 20 When the solvent is removed, the catalyst concentration is increased to a more conventional catalyst concentration. The total concentration of the catalyst metal in the first reaction zone is basically ^. To ^ 反应 ppm (weight / weight), and the catalyst metal concentration in the second reaction zone is basically in the range of 500 to 3,000 ppm (weight / weight). When Co and Mn metal catalyst systems are used, the total catalyst metal concentration in the first reaction zone should be controlled above about 250 ppm (weight / weight) to obtain good catalyst selectivity and activity. This oxidation reaction is highly exothermic. Depending on the oxygen consumption and the solvent ratio, the reaction heat will increase the temperature of the first reaction medium to higher than the operating temperature of the second reactor and / or higher than 2 without using a device to cool the reactor Grab. It is desirable to maintain the outlet temperature of the first reactor at a relatively low temperature to minimize the decomposition of solvents and precursors (i.e., combustion) and to eliminate solvent flashing when the pressure of the reaction medium decreases at the entrance to the second reaction zone. The first reaction zone may therefore include a cooling coil 18 or some other internal or external device to remove heat from the reactor (and reaction medium) to control the reaction medium outlet temperature below 2HTC and below the second The reactor operating temperature is preferred. It is important that the temperature of the coolant is about 120 ° C or above to avoid the formation of cold spots and local precipitation of terephthalic acid (TA). Maintain the rate of oxygen supply to the first reaction zone within a predetermined range and control the outlet temperature, catalyst concentration, and residence time of the reaction medium, so that the operator can control the oxygen consumption in the reaction medium to control the p-diphenylbenzene Less than 50% of the amount of oxygen required for complete conversion to TA. Therefore, according to the present invention, in the two-to-two reactor 15, p-dioxobenzene is mainly converted into TA intermediates, such as p-toluene, p-toluic acid, and 4-CBA. The aforementioned conditions and valid export -12- This paper size is applicable to the Chinese National Standard (CNS) M specification (2i0x297 public love) '~' ------- 1225479 A7 _____B7 V. Description of the invention (1.) Temperature Under control, the first reactor does not produce any solid τ A. The reaction medium leaves the first reactor 15 and enters the second reactor (i.e., the 'oxidation reaction zone) 20 via line 19, which, as shown, may be a conventional continuous stirred tank reactor. At the same time, the pressure of the reaction medium fell to the range of L20Q kPa to 2,000 kPa. As mentioned above, the purpose of reducing the pressure can be achieved simply by passing the reaction medium through one or more pressure reducing valves or nozzles 2 located around the reactor 20, whereby the reaction medium is injected into the liquid fa pipeline located in the reactor Beneath the bottom; fall off the impeller area and quickly disperse. The process conditions of reactor 2 (ie, temperature, pressure, catalyst concentration, and residence time) are within the usual range, but the oxygen consumption is reduced to reduce the oxidation reaction intensity. Oxygen source (line 22) from the first reactor 15 including nitrogen or other inert carrier gas and used or excess air entering the first reactor and newly supplied vertical or oxygen-containing gas (line 22a) Mix, introduce the resulting mixed feed gas stream and quickly disperse it in the reaction medium of the second reactor 20 by a simple device. Alternatively, used or excess air from the first reactor 15 may be directed to the condenser 24 shown via the dashed line 22b, and additional unused air or oxygen-containing gas may be directed to the second reactor 2 〇. TA will precipitate in the reaction chamber 20 to form a slurry, and can be recovered from the reactor system via line 23 using conventional methods. The reactor hallway from reactor 20 should contain some acetic acid and water, which are condensed via condenser 24, and most of the condensate is recycled (i.e., reused) via line 12 to supplement the first reaction state 15 feed stream. A portion of the acetic acid and water condensate stream (so-called derived water) is transferred to a solvent dehydration system to remove the reaction water. Depending on the situation (but not shown), a part of the condensate can be returned to the reactor 20 and enter the reaction via the re-distillation device. 13- This paper size applies to China National Standard (CNS) A4 (210X297 mm) 1225479 A7 B7 V. DESCRIPTION OF THE INVENTION (11) The reactor headspace enters the reaction zone via a separate feed line or by mixing with the exiting feed stream (line 19). Figure 2 is a simplified diagram of a preferred embodiment of the present invention. The first reaction zone (i.e., the first reactor 30) according to this embodiment is a plug flow reactor. The "plug flow reactor" as defined herein is defined as an elongated or tubular reaction zone, in which the reactant flow is rapidly and fully radially mixed as it passes through a tube or conduit. However, the present invention is not limited to any plug flow The reaction zone has a similar reactor configuration. As shown in Figure 1, the feed stream 10 is a mixed feed stream containing a circulating solvent, a circulating mother liquor, and a catalyst (via line 1 1), (ii) the second reaction Condenser condensate (via line 12) and (iii) unused acetic acid supplement (via line 13). As appropriate (but not shown), some mother liquid containing catalyst (line 11) can be bypassed to enter The second reactor 20 controls the catalyst concentration in the first reaction zone. The oxygen (line 17a) supplied in this example is essentially pure gaseous oxygen. The temperature of the mixed feed stream is usually from 13CTC to 160 ° C, depending on the temperature of the replenishing fluid. It was found to be suitable in the temperature range of about 140 ° C to initiate the oxidation reaction. With any suitable suction device 14, the pressure of the mixed feed 10 was raised to at least (but usually more than ) 2,000 kPa. The selected pressure ensures All gaseous oxygen introduced by line na will be dissolved in the feed stream before the first reactor 30 shown. After that the mixed feed stream with 'aerobic dissolution therein' will be paired with silver via line 31. Xylene simultaneously and continuously enters the plug flow reactor 30, which initiates the reaction. Para-xylene may optionally be a pre-mixture with an acetic acid solvent and this mixture is fed through line 3. As previously mentioned, optionally ， 1-14-This paper size applies Chinese National Standard (CNS) A4 specification (210X297 public love) 1225479 A7 B7 V. Description of the invention (12 Use any convenient connection to mix $ 3333 € | ι Molecule dissolved in mixed feed So that the dissolved oxygen concentration in the mixed feed stream is as high as 30% (w / w). The mixing device 33 may be a wired nozzle for discharging oxygen to the feed stream. A wired static mixer (Not shown) can also be placed upstream of each reactor 30 to facilitate mixing. Part of the para-xylene feed 31 can bypass the reactor 3G and directly enter the second reaction plutonium.-Part of the para-toluene feed 31 is fed into I 2 reactors at 0 o'clock in the first reaction The solvent in the reaction medium in the reactor: the mass ratio of para-xylene will be raised because-part of the para-xylene feed is not fed into the first reactor, so the mass ratio can reach 80: Bu high to 1 〇〇: "Go higher. According to the present invention, it is also possible to introduce oxygen in batches, that is, to introduce oxygen at multiple locations on the 30 extension line of the first reaction zone. By injecting oxygen in batches, the local maximum oxygen can be reduced. Concentration, which also reduces the operating pressure of the reactor. On the horizon, the feed stream 10 and p-xylene enter the plug flow reaction module J 0 simultaneously and continuously, thereby forming a reaction medium, in which the obtained solvent: The mono-toluene ratio is at least about 10: 1, but the solvent: para-xylene ratio can be as high as 25: i or more. In a preferred embodiment, the solvent-p-xylene ratio is in the range of 0-20: 1. The residence time in the plug flow reaction zone 30 is relatively short, i.e., less than 6 minutes. The reactor 30 shown in Fig. 2 is a shell and tube design. The reaction medium passes through the tube, and a coolant (such as compressed water (PW)) is introduced into the shell side, where the water boils and is removed in the form of steam (S). A small amount of water scrubbing gas (boiler outgassing, BB) is used to control the impurities / residuals accumulated in the water system). -15- This paper size is in accordance with Chinese National Standard (CNS) A4 specification (210X297 mm) 1225479 ----- 57___ V. Description of the invention (13) The pressure and temperature of water vapor produced by k are used to leave the first The temperature of the reaction medium of one reaction preparation is maintained below 21 ° C. As mentioned, according to the control program parameters of the present invention, the consumption of 1 of the reaction medium in the first reaction zone can be controlled such that _ Below the viewpoint of the oxygen required for complete conversion of xylene to TA. Therefore, para-xylene is basically converted into TA intermediates in the first reactor 30, such as: p-tolualdehyde, p-toluic acid and 4_CBa D. Under the control of U and the political outlet temperature, $ _ reactors 30 will not produce any solid TA. Although shown in Figure 2 is a shell and tube reactor design, the reactor 30 can be any Select the appropriate reactor P for heat removal and multiple oxygen injection devices. For example, the reaction tube can be a multiple tube, and the oxygen is injected upstream of the reaction medium of each tube. Alternatively, a reverse mixing reactor (such as: pumping Suction cycle Kushiro antizhai) 'Oxygen injection into the circuit and since The loop removes heat, as shown in Figure 3. The reactor may also contain a series of cooled or uncooled tanks, optionally injecting oxygen upstream of each tank. The embodiment shown in Figure 1 will be described In the case, the reaction medium leaving the first reaction in the plug-like flow is prepared into the second reactor (ie, the oxidation reaction zone) 20 through the pipeline 19, which may be a conventional continuous stirring tank reaction as shown in the figure. At the same time, the pressure of the reaction medium is reduced to the range of kpa to 2,0kpa. The reaction medium can be conveniently reduced by passing the reaction medium through one or more pressure reducing valves or nozzles 21 located around the reactor 20. The purpose of pressure, here, is to rapidly disperse the reaction medium by injecting it into the reactor below the liquid line and approaching the impeller region. Procedure conditions for the reactor 20 (ie, temperature, pressure, catalyst Grain and dwell time) are within the usual range, but reduce the oxygen-16-This paper size applies Chinese National Standards (CNs) A4 specifications (210X297 mm) 1225479 A7 ___B7 V. Description of the invention (14) Consumption to reduce oxidation reaction intensity Introduced without The used air or oxygen-containing gas is fed (line 22a) and quickly dispersed in the reaction medium in the second reactor 20 by any convenient means. TA will precipitate in the reactor 20 to form a slurry and can be used The conventional method recovers from the reactor system via line 23. The reactor top steam from reactor 20 should contain some acetic acid and water, which are condensed via condenser 24, and most of the condensate is circulated via line 12 (ie, Utilization) to supplement the feed stream of the first reactor 30. A portion of the acetic acid and water condensate stream (so-called derived water) is transferred to a solvent dehydration system to remove the reaction water. As appropriate (but not shown), A portion of the condensate may return to the reactor 20, enter the reactor headspace via a re-distillation unit, and / or enter the reaction zone via a separate feed line or by mixing with the exiting feed stream (line 19). -17- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)