醋酸生產外文翻譯

1、<p>　　醋酸的生產 </p><p><b>　　醋酸的生產</b></p><p><b>　　1.1醋酸</b></p><p>　　CH3COOH，也稱做乙酸，為無色水狀液體，有刺激性氣味與酸味，并有強腐蝕

2、性。為食用醋主要成分，故名。高純度（99%以上）的醋酸于16℃左右即凝結成似冰片狀結晶．故常稱冰醋酸。其蒸汽易著火，能和空氣形成爆炸性混合物。它是一種弱酸，溶解在水里只有部分水解。醋酸是含有羥基的最簡單的酸之一， 它是一個重要的化學試藥和工業(yè)的化學,被用于生產聚乙烯加工成果汁瓶；纖維素醋酸鹽主要用于制電影和照相材料；而且乙烯聚合物的醋酸鹽為木材膠, 連同合成物質纖維和織物。 在家庭中，沖淡的醋酸時常在去銹處理被人使用。在食用醋酸常被添

3、加在食物中當做酸味調味劑被使用。醋酸的全球的使用量每年 (Mt/a) 大約六百五十萬公噸, 而大約 1.5 Mt/a是又被再循環(huán); 剩余的是從石化的給料或生物學的來源制造。</p><p><b>　　1.2生產</b></p><p>　　醋酸是細菌發(fā)酵和工業(yè)生產綜合地生產。今天, 那生物生產在世界生產中只有大約 10%, 但是它依然是重要的做為醋的生產, 和大多數

4、國家一樣食品法律規(guī)定醋在食物中一定是生物制造。 大約 75% 醋酸在化學的工業(yè)中是被用于制造甲醇 , 在下面解釋。用替代選擇方法解釋那其余的。醋酸全世界的生產估計在 5 Mt/a (百萬公噸每年), 大約一半是在美國生產。有大約1百萬的萬噸在歐洲生產，0.7百萬噸在日本生產。占全球市場的6.5百萬噸每年。兩個最大的醋酸商是Celanese and BP Chemicals.其他的主要生產商有Millennium Chemicals, S

5、terling Chemicals, Samsung, Eastman, and Svensk Etanolkemi。</p><p>　　1.2.1甲醇羰基化法</p><p>　　最原始醋酸是由甲醇羰基化。在這個過程中,甲醇及一氧化碳反應生產醋酸根據化學方程式：</p><p>　　CH3OH + CO → CH3COOH。</p><p&g

6、t;　　這個過程包括碘甲烷中間體,發(fā)生在第三個步驟。一種催化劑,通常是一個復雜金屬,需要羰基化：</p><p>　　CH3OH + HI → CH3I + H2O CH3I + CO → CH3COI CH3COI + H2O → CH3COOH + HI</p><p>　　通過改變工藝條件、乙酸酐也可能產生相同的物質。由于甲醇及一氧化碳是商品的原材料、甲醇羰基化長似乎是一個具有吸

7、引力的方法對醋酸生產。亨利在英國塞拉尼斯研制出一種Drefyus甲醇羰基化中試驗早在1925年。然而,缺乏實用的材料,可以包含了腐蝕反應混合物在高壓需要(200 atm或更多)的商品化的底線。第一個商用甲醇羰基化過程,用鈷催化劑,是由德國巴斯夫化學公司在1963年。在1968年,一個rhodium-based催化劑(cis?[Rh(CO)2I2]?)被發(fā)現,能在較低的壓力的運作效率和幾乎沒有副產品。第一個工廠用這種催化劑的化學公司建立了

8、公司在1970年,孟山都公司rhodium-catalysed甲醇羰基化成為主要醋酸法生產工藝(見孟山都公司)。在1990年代末期,化工公司BP化工商業(yè)化的Cativa催化劑([紅外(CO)2I2]?),它是由釕。這iridium-catalysed過程是綠色的、更高效的并已在很大程度上取代了孟山都公司的生產過程,經常在同一生產工段。</p><p>　　1.2.3乙醛氧化法</p><p&g

9、t;　　之前的商業(yè)化進程,大多數醋酸生產孟山都公司是由氧化乙醛法制得。這仍然是第二個最重要的生產方法,雖然它沒有競爭力與甲醇羰基化法相比?？赡墚a生乙醛丁烷通過氧化汽油、或水化的乙烯。當丁烷和空氣受熱石腦油面對不同的金屬離子，其中包括錳、鈷、鉻、過氧化物,然后分解生產醋酸根據化學方程式：</p><p>　　2 C4H10 + 5 O2 → 4 CH3COOH + 2 H2O</p><p>

10、;　　一般情況下,反應是運行在一個綜合設計的溫度和壓力溫度下,仍然盡可能保持著丁烷為液體。典型的反應條件是150攝氏度,55個大氣壓下。生產的產品也是各種各樣的形式,包括butanone、乙酸乙酯、甲酸、丙酸。這樣的產品也是具有商業(yè)價值的,反應條件的改變使它們的產生更多產品。假如這是經濟實用的。然而，這些副產品是醋酸的成本增加在生產過程中。在相同條件下,使用相似的催化劑是用于丁烷氧化、乙醛可以通過空氣中的氧氣氧化生產醋酸。</p&

11、gt;<p>　　2 CH3CHO + O2 → 2 CH3COOH</p><p>　　運用現代的催化劑,該反應具有醋酸乙酯使收率大于95%。主要副產品有乙酸乙酯、甲酸、甲醛，它們具有低沸點、容易被升華與乙酸相比。</p><p>　　1.2.4乙烯氧化法</p><p>　　該法有間接法與直接法之分，間接法即乙烯－乙醛氧化法，在20世紀60年代發(fā)展

12、迅速，但是隨著Monsanto甲醇羰基化工藝的發(fā)展，乙烯－乙醛法的比重逐步減少，這是因為該法在技術經濟各項指標上不及甲醇羰基化工藝。目前該工藝仍是我國醋酸的主要生產方法。該工藝以乙醛為原料，采用醋酸錳、醋酸鈷或醋酸銅液相催化劑，在50～80 ℃、0.6～0.8 MPa進行氧化反應，乙醛轉化率在90％以上，醋酸選擇性高于95％。工藝用的所有設備必須采用不銹鋼材料。    日本昭和電工采用直接法，即不經過乙醛的醋酸生產

13、工藝于1997年在千葉工廠建成一套生產能力為100 kt/a的醋酸裝置，該裝置采用鈀系新催化劑，反應在固定床反應器內進行，反應溫度約150～160 ℃，壓力約0.9 MPa，乙烯單程轉化率為7.4%，醋酸、乙醛、CO2的選擇性分別為86.4%、8.1%和5.1%。與類似規(guī)模的甲醇法和乙醛法裝置比較，直接氧化法裝置的建造成本明顯降低，而裝置規(guī)模可根據用戶要求來設計。另外該工藝非常簡單，廢水排放量明顯下降，僅為乙醛氧化法的十分之一。<

14、;/p><p>　　Acetic Acid Production</p><p>　　1.Acetic Acid Production</p><p>　　1.1 Acetic Acid</p><p>　　Acetic Acid, CH3COOH, also known as ethanoic acid, is an organic acid

15、which gives vinegar its sour taste and pungent smell. Pure, water-free acetic acid (glacial acetic acid) is a colourless liquid that absorbs water from the environment (hygroscopy), and freezes at 16.7 °C (62 °

16、F) to a colourless crystalline solid. It is a weak acid, in that it is only partially dissociated acid in aqueous solution.</p><p>　　Acetic acid is one of the simplest carboxylic acids. It is an important ch

17、emical reagent and industrial chemical, used in the production of polyethylene terephthalate mainly used in soft drink bottles; cellulose acetate, mainly for photographic film; and polyvinyl acetate for wood glue, as wel

18、l as synthetic fibres and fabrics. In households, diluted acetic acid is often used in descaling agents. In the food industry acetic acid is used under the food additive code E260 as an acidity regulator.</p><

19、p>　　The global demand of acetic acid is around 6.5 million tonnes per year (Mt/a), of which approximately 1.5 Mt/a is met by recycling; the remainder is manufactured from petrochemical feedstocks or from biological so

20、urces. </p><p>　　1.2 Production</p><p>　　Acetic acid is produced both synthetically and by bacterial fermentation. Today, the biological route accounts for only about 10% of world production, bu

21、t it remains important for vinegar production, as many nations' food purity laws stipulate that vinegar used in foods must be of biological origin. About 75% of acetic acid made for use in the chemical industry is ma

22、de by methanol carbonylation, explained below. Alternative methods account for the rest. Total worldwide production of virgin aceti</p><p>　　1.2.1 Methanol carbonylation Most virgin acetic acid is produ

23、ced by methanol carbonylation. In this process, methanol and carbon monoxide react to produce acetic acid according to the chemical equation:CH3OH + CO → CH3COOH</p><p>　　The process involves iodomethane as

24、 an intermediate, and occurs in three steps. A catalyst, usually a metal complex, is needed for the carbonylation (step 2).CH3OH + HI → CH3I + H2O CH3I + CO → CH3COI CH3COI + H2O → CH3COOH + HI </p><p>　　

25、By altering the process conditions, acetic anhydride may also be produced on the same plant. Because both methanol and carbon monoxide are commodity raw materials, methanol carbonylation long appeared to be an attractive

26、 method for acetic acid production. Henry Drefyus at British Celanese developed a methanol carbonylation pilot plant as early as 1925. However, a lack of practical materials that could contain the corrosive reaction mixt

27、ure at the high pressures needed (200 atm or more) discourag</p><p>　　1.2.3 Acetaldehyde oxidation</p><p>　　Prior to the commercialization of the Monsanto process, most acetic acid was produced

28、by oxidation of acetaldehyde. This remains the second most important manufacturing method, although it is uncompetitive with methanol carbonylation.</p><p>　　The acetaldehyde may be produced via oxidation of

29、 butane or light naphtha, or by hydration of ethylene. When butane or light naphtha is heated with air in the presence of various metal ions, including those of manganese, cobalt and chromium; peroxides form and then dec

30、ompose to produce acetic acid according to the chemical equation:2 C4H10 + 5 O2 → 4 CH3COOH + 2 H2O</p><p>　　Typically, the reaction is run at a combination of temperature and pressure designed to be as hot

31、 as possible while still keeping the butane a liquid. Typical reaction conditions are 150 °C and 55 atm. Side products may also form, including butanone, ethyl acetate, formic acid, and propionic acid. These

32、side products are also commercially valuable, and the reaction conditions may be altered to produce more of them if this is economically useful. However, the separation of acetic acid from</p><p>　　Under sim

33、ilar conditions and using similar catalysts as are used for butane oxidation, acetaldehyde can be oxidized by the oxygen in air to produce acetic acid:2 CH3CHO + O2 → 2 CH3COOH </p><p>　　Using modern cataly

34、sts, this reaction can have an acetic acid yield greater than 95%. The major side products are ethyl acetate, formic acid, and formaldehyde, all of which have lower boiling points than acetic acid and are readily separat

35、ed by distillation.</p><p>　　1.2.4 Ethylene oxidation Acetaldehyde may be prepared from ethylene via the Wacker process, and then oxidized as above. More recently a cheaper single-stage conversion of e

36、thylene to acetic acid was commercialized by chemical company Showa Denko, which opened an ethylene oxidation plant in ōita, Japan, in 1997. The process is catalysed by a palladium metal catalyst supported on a heteropol