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其它類型的蒸餾

放大字體  縮小字體 發(fā)布日期:2008-09-18
核心提示:In rotary evaporation a vacuum distillation apparatus is used to remove bulk solvents from a sample. Typically the vacuum is generated by a water aspirator or a membrane pump. In a kugelrohr a short path distillation apparatus is typically used (gen


In rotary evaporation a vacuum distillation apparatus is used to remove bulk solvents from a sample. Typically the vacuum is generated by a water aspirator or a membrane pump.

In a kugelrohr a short path distillation apparatus is typically used (generally in combination with a (high) vacuum) to distill high boiling (> 300 °C) compounds. The apparatus consists of an oven in which the compound to be distilled is placed, a receiving portion which is outside of the oven, and a means of rotating the sample. The vacuum is normally generated by using a high vacuum pump.

The process of reactive distillation involves using the reaction vessel as the still. In this process, the product is usually significantly lower-boiling than its reactants. As the product is formed from the reactants, it is vaporized and removed from the reaction mixture. This technique is an example of a continuous vs. a batch process; advantages include less downtime to charge the reaction vessel with starting material, and less workup.

Destructive distillation involves the strong heating of solids (often organic material) in the absence of oxygen (to prevent combustion) to evaporate various high-boiling liquids, as well as thermolysis products. The gases evolved are cooled and condensed as in normal distillation. The destructive distillation of wood to give methanol is the root of its common name - wood alcohol.

Pervaporation is a method for the separation of mixtures of liquids by partial vaporization through a non-porous membrane.

Dry distillation, despite its name, is not truly distillation, but rather a chemical reaction known as pyrolysis in which solid substances are heated in a strongly reducing atmosphere and any volatile fractions are collected.

Extractive distillation is defined as distillation in the presence of a miscible, high boiling, relatively non-volatile component, the solvent, that forms no azeotrope with the other components in the mixture.

Flash evaporation (or partial evaporation) is the partial vaporization that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through a throttling valve or other throttling device. This process is one of the simplest unit operations.

Freeze distillation is an analogous method of purification using freezing instead of evaporation. It is not truly distillation, and does not produce products equivalent to distillation. This process is used in the production of ice beer and ice wine to increase ethanol and sugar content, respectively.

Codistillation is distillation which is performed on mixtures in which the two compounds are not miscible.

在旋轉(zhuǎn)蒸發(fā)中,使用真空蒸餾設(shè)備將大量的溶劑從樣品內(nèi)除去。真空由水抽子或隔膜泵產(chǎn)生。

在kugelrohr蒸餾中,通常使用短程蒸餾設(shè)備(一般與高真空結(jié)合),以蒸餾高沸點(> 300 °C)的化合物。該設(shè)備包括一個放置被蒸餾的化合物的爐子,一個處于爐子外的接收部分以及樣品旋轉(zhuǎn)設(shè)備。一般使用高真空泵來產(chǎn)生真空。

反應(yīng)蒸餾的過程涉及到用作反應(yīng)釜的蒸餾釜。在這一過程中,反應(yīng)產(chǎn)物的沸點比反應(yīng)物沸點低得多。產(chǎn)物由反應(yīng)物形成的同時,就被汽化并從反應(yīng)混合物中去除。該技術(shù)是連續(xù)式蒸餾與間歇式蒸餾相對的例子。優(yōu)點包括:給反應(yīng)釜內(nèi)添加原料的停工時間少;工作量小。

分解蒸餾涉及到對固體物質(zhì)(常為有機物)在缺氧條件下的強烈加熱(以防燃燒),以蒸餾去各種高沸液體及熱分解產(chǎn)物。與常規(guī)蒸餾一樣,分解蒸餾中所產(chǎn)生的氣體被冷卻并冷凝下來。產(chǎn)出甲醇的木材分解蒸餾是甲醇普通名稱(木醇)的根源。

滲透蒸發(fā)是一種通過非多孔膜對液體混合物進行部分汽化的分離方法。

干餾,盡管名稱如此,但實際上不是蒸餾,而是一種廣為人知的熱分解反應(yīng),反應(yīng)中,固體物質(zhì)在強烈的減壓狀態(tài)下受熱,任何揮發(fā)性組分都被收集下來。

淬取蒸餾的定義為:有易混合的、高沸的、相對難揮發(fā)的組分和溶劑存在下的蒸餾,且這些組分和溶劑不與混合物中的其它組分形成恒沸物。

快速蒸發(fā)(或部分蒸發(fā))是讓飽和液流通過節(jié)流閥或其它節(jié)流裝置,使其經(jīng)歷壓力減小而發(fā)生的部分汽化。


冷凍蒸餾是一種用冷凍代替汽化的類似的提純方法。它其實不是蒸餾,也不產(chǎn)生與蒸餾等同的產(chǎn)物。此法用于冰啤酒和冰葡萄酒的生產(chǎn)中,以分別增加乙醇和糖的含量

共餾是對由不易混合的兩種化合物組成的混合物進行的蒸餾。

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