Laboratory distillation set-up: 1: Heat source 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed control 13: Stirrer/heat plate 14: Heating (Oil/sand) bath 15: Stiring means e. g. magnetic follower (shown), anti-bumping granules or mechanical stirrer 16: Cooling bath.

Distillation is a method of separating chemical substances based on differences in their volatilities in a boiling liquid mixture. In Chemistry and Chemical engineering, a separation process is used to transform a Mixture of substances into two or more distinct products A chemical substance is a Material with a definite chemical composition. Volatility in the context of Chemistry, Physics and Thermodynamics is a measure of the tendency of a substance to Vaporize. Distillation usually forms part of a larger chemical process, and is thus referred to as a unit operation. In Chemical engineering and related fields a unit operation is a basic step in a Process.

Commercially, distillation has a number of uses. It is used to separate crude oil into more fractions for specific uses such as transport, power generation and heating. Petroleum ( L petroleum, from Greek πετρέλαιον, lit Transport or transportation is the movement of people and goods from one place to another Electricity generation is the process of converting non-electrical Energy to Electricity. Water is distilled to remove impurities, such as salt from sea water. Air is distilled to separate its components - notably oxygen, nitrogen and argon - for industrial use. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 This article pertains to the chemical element For other uses see Argon (disambiguation. Distillation of fermented solutions has been used since ancient times to produce distilled beverages with a higher alcohol content. Fermentation in Food processing typically refers to the conversion of Sugar to Alcohol using Yeast under Anaerobic conditions In Chemistry, a solution is a Homogeneous Mixture composed of two or more substances

History

Early forms of distillation were known to Babylonian alchemists in Mesopotamia (in what is now Iraq) from at least the 2nd millennium BC. Babylonia was an Amorite state in lower Mesopotamia (modern southern Iraq) with Babylon as its capital Alchemy a part of the Occult Tradition is both a philosophy and a practice with an ultimately unknown aim involving the improvement of the alchemist as well as the making of Mesopotamia (from the Greek meaning "land between the rivers" is an area geographically located between the Tigris and Euphrates rivers largely corresponding For a topic outline on this subject see List of basic Iraq topics. The 2nd millennium BC marks the transition from the Middle to the Late Bronze Age. ^[1] Archaeological excavations in northwest Pakistan, have yielded evidence that the distillation of alcohol was known in South Asia since 500 BCE. Pakistan () officially the Islamic Republic of Pakistan, is a country located in South Asia, Southwest Asia, Middle East and ^[2] But only became common between 150 BCE- 350 CE. ^[2] Distillation was later known to Greek alchemists from the 1st century AD,^[3][4][5] and the later development of large-scale distillation apparatus occurred in response to demands for spirits. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly The 1st century was the Century that lasted from 1 to 100 according the Julian calendar. ^[3] Hypathia of Alexandria is credited with having invented an early distillation apparatus,^[6] and the first exact description of apparatus for distillation is given by Zosimos of Alexandria in the fourth century. Hypatia of Alexandria (haɪˈpeɪʃə ( Greek:; born between AD 350 and 370 – 415 was a Greek scholar from Alexandria in Egypt, considered Alexandria ( Egyptian Arabic: اسكندريه Eskendereyya; Standard Arabic: ar الإسكندرية Al-Iskandariyya; Ἀλεξάνδρεια ^[5] Primitive tribes of India used a method of distillation for producing Mahuda liquor. This crude and ancient method is not very effective. ^[7]

Distillation by retort using the alembic. In a Chemistry laboratory a retort is a glassware device used for Distillation or Dry distillation of substances An alembic (from Arabic Al-inbiq الأنبيق is an alchemical Still consisting of two Retorts connected by a tube

In the 8th century, alchemists in the Middle East produced distillation processes to purify chemical substances for industrial purposes such as isolating natural esters (perfumes) and producing pure alcohol. A chemical substance is a Material with a definite chemical composition. For other uses of this term see Industry (disambiguation An industry (from Latin industrius, "diligent industrious" Esters are a class of Chemical compounds and Functional groups Esters consist of an inorganic or organic Acid in which at least Perfume is a mixture of fragrant Essential oils and Aroma compounds Fixatives and Solvents used to give the human body animals objects and living In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon ^[8] The first among them was the Persian Jabir ibn Hayyan (Geber) circa 800 AD, who is credited with the invention of numerous chemical apparatus and processes that are still in use today. The Persian Empire was a series of Iranian empires that ruled over the Iranian plateau, the original Persian homeland and beyond in Western Asia For the 12th century astronomer see Jabir ibn Aflah. For the anonymous 14th century Spanish alchemist see Pseudo-Geber. In particular, his alembic was the first still with retorts which could fully purify chemicals, a precursor to the pot still, and its design has served as inspiration for modern micro-scale distillation apparatus such as the Hickman stillhead. An alembic (from Arabic Al-inbiq الأنبيق is an alchemical Still consisting of two Retorts connected by a tube A still is an apparatus used to distill Miscible or immiscible (eg In a Chemistry laboratory a retort is a glassware device used for Distillation or Dry distillation of substances A pot still is a type of Still used in distilling spirits such as Whisky or Brandy. ^[9] Petroleum was first distilled by another Persian, al-Razi (Rhazes) in the 9th century, for producing kerosene,^[10] while steam distillation was invented by Avicenna in the early 11th century, for producing essential oils. Petroleum ( L petroleum, from Greek πετρέλαιον, lit The Persian Empire was a series of Iranian empires that ruled over the Iranian plateau, the original Persian homeland and beyond in Western Asia Kerosene, sometimes spelled kerosine in scientific and industrial usage is a Combustible Hydrocarbon liquid Steam distillation is a special type of Distillation (a separation process) for temperature sensitive materials like natural aromatic compounds TemplateInfobox Muslim scholars --> ( Persian /ابو علی الحسین ابن عبدالله ابن سینا (born An essential oil is a concentrated Hydrophobic Liquid containing volatile Aroma compounds from Plants They are also known as volatile ^[11] As the works of Middle Eastern scribes made their way to India and became a part of Indian alchemy, several texts dedicated to distillation made their way to Indian libraries. ^[12] Among these was a treatise written by a scholar from Bagdad in 1034 titled Ainu-s-Sana'ah wa' Auna-s-Sana'ah. ^[12] Scholar Al-Jawbari travelled to India. ^[13] By the time of the writing of the Ain-e-Akbari, the process of distillation was well known in India. The Ain-i-Akbari or the "Institutes of Akbar" is a 16th century detailed document recording the administration of emperor Akbar 's empire written by his Vizier ^[14]

In 1500, German alchemist Hieronymus Braunschweig published Liber de arte destillandi (The Book of the Art of Distillation)[1] the first book on the subject, followed in 1512 by a much expanded version. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe.

In 1651, John French published The Art of Distillation the first major English compendium of practice, though it has been claimed^[15] that much of it derives from Braunschweig's work. John French (1616-1657 was an English doctor known for his contributions to Chemistry and in particular to Distillation. This includes diagrams with people in them showing the industrial rather than bench scale of the operation.

As alchemy evolved into the science of chemistry, vessels called retorts became used for distillations. Alchemy a part of the Occult Tradition is both a philosophy and a practice with an ultimately unknown aim involving the improvement of the alchemist as well as the making of Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties In a Chemistry laboratory a retort is a glassware device used for Distillation or Dry distillation of substances Both alembics and retorts are forms of glassware with long necks pointing to the side at a downward angle which acted as air-cooled condensers to condense the distillate and let it drip downward for collection. Laboratory glassware refers to a variety of equipment traditionally made of Glass, used for Scientific experiments and other work in Science, especially For other Condensers not involving heat transfer see Condenser (disambiguation Condensation is the change of the physical state of aggregation (or simply state of matter from gaseous phase into liquid phase

Later, copper alembics were invented. Riveted joints were often kept tight by using various mixtures, for instance a dough made of rye flour. ^[16] These alembics often featured a cooling system around the beak, using cold water for instance, which made the condensation of alcohol more efficient. These were called pot stills. A pot still is a type of Still used in distilling spirits such as Whisky or Brandy.

Today, the retorts and pot stills have been largely supplanted by more efficient distillation methods in most industrial processes. However, the pot still is still widely used for the elaboration of some fine alcohols such as cognac, Scotch whisky and some vodkas. Cognac (ˈkɒnjæk named after the town of Cognac in France, is a Brandy produced in the region surrounding the town Scotch whisky is Whisky made in Scotland. In Britain the term whisky is usually taken to mean Scotch unless otherwise specified Vodka is one of the world's most popular Distilled beverages It is a clear liquid which consists of mostly Water and Ethanol purified by Distillation Pot stills made of various materials (wood, clay, stainless steel) are also used by bootleggers in various countries. Rum-running is the business of Smuggling or transporting of Alcoholic beverages illegally usually to circumvent Taxation or Prohibition. Small pot stills are also sold for the domestic production^[17] of flower water or essential oils. An essential oil is a concentrated Hydrophobic Liquid containing volatile Aroma compounds from Plants They are also known as volatile

Early forms of distillation were batch processes using one vaporization and one condensation. Purity was improved by further distillation of the condensate. Greater volumes were processed by simply repeating the distillation. Chemists were reported to carry out as many as 500 to 600 distillations in order to obtain a pure compound^[18].

In the early 19th century the basics of modern techniques including pre-heating and reflux were developed, particularly by the French^[18], then in 1830 a British Patent was issued to Aeneas Coffey for a whiskey distillation column^[19], which worked continuously and may be regarded as the archetype of modern petrochemical units. For the game see 1830 (board game. Year 1830 ( MDCCCXXX) was a Common year starting on Friday (link will display A patent is a set of Exclusive rights granted by a State to an inventor or his assignee for a fixed period of time in exchange for a disclosure of an Aeneas Coffey (1780-1852 was born in Calais, France, where he spent his early years An archetype ( pronounced: /ˈɑːkɪtaɪp/ (Brit or /ˈɑrkɪtaɪp/ (Amer In 1877, Ernest Solvay was granted a U. Year 1877 ( MDCCCLXXVII) was a Common year starting on Monday (link will display the full calendar of the Gregorian calendar (or a Common Ernest Gaston Joseph Solvay ( 16 April 1838 - 26 May 1922) was a Belgian Chemist, Industrialist and Philanthropist S. Patent for a tray column for ammonia distillation^[20] and the same and subsequent years saw developments of this theme for oil and spirits. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor

With the emergence of chemical engineering as a discipline at the end of the 19th century, scientific rather than empirical methods could be applied. Chemical engineering is the branch of Engineering that deals with the application of Physical science (e The developing petroleum industry in the early 20th century provided the impetus for the development of accurate design methods such as the McCabe-Thiele method and the Fenske equation. Petroleum ( L petroleum, from Greek πετρέλαιον, lit The graphical approach presented by McCabe and Thiele in 1925 the McCabe-Thiele method is considered the simplest and perhaps most instructive method for analysis of binary Distillation The Fenske equation in continuous Fractional distillation is an Equation used for calculating the minimum number of theoretical plates required for the

Applications of distillation

The application of distillation can roughly be divided in four groups: laboratory scale, industrial distillation, distillation of herbs for perfumery and medicinals (herbal distillate) and food processing. Herbal distillates are aqueous solutions or colloidal suspensions (hydrosol of Essential oils usually obtained by Steam distillation from aromatic plants The latter two are distinct from the former two, in that in the distillation is not used as a true purification method, but more to transfer all volatiles from the source materials to the distillate. Volatility in the context of Chemistry, Physics and Thermodynamics is a measure of the tendency of a substance to Vaporize.

The main difference between laboratory scale distillation and industrial distillation is that laboratory scale distillation is often performed batch-wise, whereas industrial distillation often occurs continuously. In batch distillation, the composition of the source material, the vapors of the distilling compounds and the distillate change during the distillation. Batch distillation refers to the use of Distillation in batches meaning that a mixture is distilled to separate it into its component fractions before the distillation still In batch distillation, a still is charged (supplied) with a batch of feed mixture, which is then separated into its component fractions which are collected sequentially from most volatile to less volatile, with the bottoms (remaining least or non-volatile fraction) removed at the end. The still can then be recharged and the process repeated.

In continuous distillation, the source materials, vapors and distillate are kept at a constant composition by carefully replenishing the source material and removing fractions from both vapor and liquid in the system. Continuous distillation, a form of Distillation, is an ongoing separation in which a mixture is continuously (without interruption fed into the process and separated fractions This results in a better control of the separation process.

Idealized distillation model

The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid. The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid Vapor pressure (also known as equilibrium vapor pressure or saturation vapor pressure) is the Pressure of a Vapor in equilibrium The normal boiling point of a liquid is the special case at which the vapor pressure of the liquid equals the ambient atmospheric pressure. The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid A liquid in a container at a pressure below atmospheric pressure will boil at temperature lower than the normal boiling point, and a liquid in a container at a pressure higher than atmospheric pressure will boil at a temperature higher than the normal boiling point.

It is a common misconception that in a liquid mixture at a given pressure, each component boils at the boiling point corresponding to the given pressure and the vapors of each component will collect separately and purely. This, however, does not occur even in an idealized system. Idealized models of distillation are essentially governed by Raoult's law and Dalton's law. Established by François-Marie Raoult, Raoult's law states the Vapor pressure of an Ideal solution is dependent on the vapor pressure of each In Chemistry and Physics, Dalton's law (also called Dalton's law of partial pressures) states that the total Pressure exerted by a

Raoult's law assumes that a component contributes to the total vapor pressure of the mixture in proportion to its percentage of the mixture and its vapor pressure when pure. Vapor pressure (also known as equilibrium vapor pressure or saturation vapor pressure) is the Pressure of a Vapor in equilibrium If one component changes another component's vapor pressure, or if the volatility of a component is dependent on its percentage in the mixture, the law will fail.

Dalton's law states that the total vapor pressure is the sum of the vapor pressures of each individual component in the mixture. When a multi-component liquid is heated, the vapor pressure of each component will rise, thus causing the total vapor pressure to rise. When the total vapor pressure reaches the pressure surrounding the liquid, boiling occurs and liquid turns to gas throughout the bulk of the liquid. Boiling (also called ebullition) a type of Phase transition, is the rapid vaporization of a Liquid, which typically occurs when a liquid Note that a given mixture has one boiling point at a given pressure, when the components are mutually soluble.

The idealized model is accurate in the case of chemically similar liquids, such as benzene and toluene. Benzene, or benzol, is an organic Chemical compound and a known Carcinogen with the molecular formula C 6 H 6 Toluene, also known as methylbenzene or phenylmethane, is a clear water -insoluble liquid with the typical smell of Paint thinners redolent of In other cases, severe deviations from Raoult's law and Dalton's law are observed, most famously in the mixture of ethanol and water. These compounds, when heated together, form an azeotrope, in which the boiling temperature of the mixture is lower than the boiling temperature of each separate liquid. An azeotrope (pronounced Virtually all liquids, when mixed and heated, will display azeotropic behaviour. Although there are computational methods that can be used to estimate the behavior of a mixture of arbitrary components, the only way to obtain accurate vapor-liquid equilibrium data is by measurement. Computational chemistry is a branch of Chemistry that uses computers to assist in solving chemical problems Vapor-liquid equilibrium, abbreviated as VLE by some is a condition where a Liquid and its Vapor (gas phase are in equilibrium with each other

It is not possible to completely purify a mixture of components by distillation, as this would require each component in the mixture to have a zero partial pressure. In a mixture of Ideal gases each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume If ultra-pure products are the goal, then further chemical separation must be applied. In Chemistry and Chemical engineering, a separation process is used to transform a Mixture of substances into two or more distinct products

Batch distillation

Main article: Batch distillation

A batch still showing the separation of A and B. Batch distillation refers to the use of Distillation in batches meaning that a mixture is distilled to separate it into its component fractions before the distillation still

Heating an ideal mixture of two volatile substances A and B (with A having the higher volatility, or lower boiling point) in a batch distillation setup (such as in an apparatus depicted in the opening figure) until the mixture is boiling results in a vapor above the liquid which contains a mixture of A and B. The ratio between A and B in the vapor will be different from the ratio in the liquid: the ratio in the liquid will be determined by how the original mixture was prepared, while the ratio in the vapor will be enriched in the more volatile compound, A (due to Raoult's Law, see above). The vapor goes through the condenser and is removed from the system. This in turn means that the ratio of compounds in the remaining liquid is now different from the initial ratio (i. e. more enriched in B than the starting liquid).

The result is that the ratio in the liquid mixture is changing, becoming richer in component B. This causes the boiling point of the mixture to rise, which in turn results in a rise in the temperature in the vapor, which results in a changing ratio of A : B in the gas phase (as distillation continues, there is an increasing proportion of B in the gas phase). This results in a slowly changing ratio A : B in the distillate.

If the difference in vapor pressure between the two components A and B is large (generally expressed as the difference in boiling points), the mixture in the beginning of the distillation is highly enriched in component A, and when component A has distilled off, the boiling liquid is enriched in component B.

Continuous distillation

Main article: Continuous distillation

Continuous distillation is an ongoing distillation in which a liquid mixture is continuously (without interruption) fed into the process and separated fractions are removed continuously as output streams as time passes during the operation. Continuous distillation, a form of Distillation, is an ongoing separation in which a mixture is continuously (without interruption fed into the process and separated fractions Continuous distillation produces at least two output fractions, including at least one volatile distillate fraction, which has boiled and been separately captured as a vapor condensed to a liquid. Volatility in the context of Chemistry, Physics and Thermodynamics is a measure of the tendency of a substance to Vaporize. There is always a bottoms (or residue) fraction, which is the least volatile residue that has not been separately captured as a condensed vapor.

General improvements

Both batch and continuous distillations can be improved by making use of a fractionating column on top of the distillation flask. A fractionating column or fractionation column is an essential item used in the Distillation of liquid mixtures so as to separate the mixture into its component parts The column improves separation by providing a larger surface area for the vapor and condensate to come into contact. This helps it remain at equilibrium for as long as possible. The column can even consist of small subsystems ('trays' or 'dishes') which all contain an enriched, boiling liquid mixture, all with their own vapor-liquid equilibrium.

There are differences between laboratory-scale and industrial-scale fractionating columns, but the principles are the same. Examples of laboratory-scale fractionating columns (in increasing efficacy) include:

• Air condenser
• Vigreux column (usually laboratory scale only)
• Packed column (packed with glass beads, metal pieces, or other chemically inert material)
• Spinning band distillation system

Laboratory scale distillation

Laboratory scale distillations are almost exclusively run as batch distillations. In a Laboratory, a condenser is a piece of Laboratory glassware used to cool hot vapors or liquids In a Laboratory, a condenser is a piece of Laboratory glassware used to cool hot vapors or liquids In Chemical processing a packed bed is a hollow tube, pipe or other vessel that is filled with a packing material Spinning band distillation is a technique used to separate liquid mixtures which are similar in boiling points The device used in distillation, sometimes referred to as a still, consists at a minimum of a reboiler or pot in which the source material is heated, a condenser in which the heated vapour is cooled back to the liquid state, and a receiver in which the concentrated or purified liquid, called the distillate, is collected. A still is an apparatus used to distill Miscible or immiscible (eg This page is about the physical properties of gas as a state of matter In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties Several laboratory scale techniques for distillation exist (see also distillation types).

Simple distillation

In simple distillation, all the hot vapors produced are immediately channeled into a condenser which cools and condenses the vapors. Therefore, the distillate will not be pure - its composition will be identical to the composition of the vapors at the given temperature and pressure, and can be computed from Raoult's law. Established by François-Marie Raoult, Raoult's law states the Vapor pressure of an Ideal solution is dependent on the vapor pressure of each

As a result, simple distillation is usually used only to separate liquids whose boiling points differ greatly (rule of thumb is 25 °C),^[21] or to separate liquids from involatile solids or oils. For these cases, the vapor pressures of the components are usually sufficiently different that Raoult's law may be neglected due to the insignificant contribution of the less volatile component. In this case, the distillate may be sufficiently pure for its intended purpose.

Fractional distillation

Main article: Fractional distillation

For many cases, the boiling points of the components in the mixture will be sufficiently close that Raoult's law must be taken into consideration. Fractional distillation is the separation of a mixture into its component parts or fractions such as in separating Chemical compounds by their Boiling point by heating Therefore, fractional distillation must be used in order to separate the components well by repeated vaporization-condensation cycles within a packed fractionating column.

As the solution to be purified is heated, its vapors rise to the fractionating column. A fractionating column or fractionation column is an essential item used in the Distillation of liquid mixtures so as to separate the mixture into its component parts As it rises, it cools, condensing on the condenser walls and the surfaces of the packing material. Here, the condensate continues to be heated by the rising hot vapors; it vaporizes once more. However, the composition of the fresh vapors are determined once again by Raoult's law. Each vaporization-condensation cycle (called a theoretical plate) will yield a purer solution of the more volatile component. A theoretical plate in many Separation processes is a hypothetical zone or stage in which two phases such as the Liquid and Vapor phases of a substance ^[22] In reality, each cycle at a given temperature does not occur at exactly the same position in the fractionating column; theoretical plate is thus a concept rather than an accurate description.

More theoretical plates lead to better separations. A spinning band distillation system uses a spinning band of Teflon or metal to force the rising vapors into close contact with the descending condensate, increasing the number of theoretical plates. Spinning band distillation is a technique used to separate liquid mixtures which are similar in boiling points In Chemistry, poly(tetrafluoroethene or poly(tetrafluoroethylene ( PTFE) is a synthetic Fluoropolymer which finds numerous applications ^[23]

Steam distillation

Main article: Steam distillation

Like vacuum distillation, steam distillation is a method for distilling compounds which are heat-sensitive. Steam distillation is a special type of Distillation (a separation process) for temperature sensitive materials like natural aromatic compounds Vacuum distillation is a method of Distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its Vapor pressure (usually This process involves using bubbling steam through a heated mixture of the raw material. By Raoult's law, some of the target compound will vaporize (in accordance with its partial pressure). The vapor mixture is cooled and condensed, usually yielding a layer of oil and a layer of water.

Steam distillation of various aromatic herbs and flowers can result in two products; an essential oil as well as a watery herbal distillate. An essential oil is a concentrated Hydrophobic Liquid containing volatile Aroma compounds from Plants They are also known as volatile Herbal distillates are aqueous solutions or colloidal suspensions (hydrosol of Essential oils usually obtained by Steam distillation from aromatic plants The essential oils are often used in perfumery and aromatherapy while the watery distillates have many applications in aromatherapy, food processing and skin care. An essential oil is a concentrated Hydrophobic Liquid containing volatile Aroma compounds from Plants They are also known as volatile Aromatherapy is a form of Alternative medicine that uses volatile liquid plant materials known as Essential oils (EOs and other aromatic compounds from plants for Aromatherapy is a form of Alternative medicine that uses volatile liquid plant materials known as Essential oils (EOs and other aromatic compounds from plants for Food processing is the set of methods and techniques used to transform raw Ingredients into Food or to transform food into other forms for consumption by The skin is the outer covering of living tissue of an animal (or plant

Dimethyl sulfoxide usually boils at 189 °C. Dimethyl sulfoxide (DMSO is the Chemical compound with the formula (CH32SO Under a vacuum, it distills off into the receiver at only 70 °C.

Perkin Triangle Distillation Setup
1: Stirrer bar/anti-bumping granules 2: Still pot 3: Fractionating column 4: Thermometer/Boiling point temperature 5: Teflon tap 1 6: Cold finger 7: Cooling water out 8: Cooling water in 9: Teflon tap 2 10: Vacuum/gas inlet 11: Teflon tap 3 12: Still receiver

Vacuum distillation

Main article: Vacuum distillation

Some compounds have very high boiling points. Vacuum distillation is a method of Distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its Vapor pressure (usually To boil such compounds, it is often better to lower the pressure at which such compounds are boiled instead of increasing the temperature. Once the pressure is lowered to the vapor pressure of the compound (at the given temperature), boiling and the rest of the distillation process can commence. This technique is referred to as vacuum distillation and it is commonly found in the laboratory in the form of the rotary evaporator. A rotary evaporator (or rotavap) is a device used in Chemical laboratories for the efficient and gentle removal of Solvents from samples by Evaporation

This technique is also very useful for compounds which boil beyond their decomposition temperature at atmospheric pressure and which would therefore be decomposed by any attempt to boil them under atmospheric pressure. For the biological process see Decomposition. For chemical decomposition in general see Chemical decomposition.

Air-sensitive vacuum distillation

Some compounds have high boiling points as well as being air sensitive. Air sensitive is a term used particularly in Chemistry, to denote Compounds that react with Air; typically with atmospheric Oxygen (O2 A simple vacuum distillation system as exemplified above can be used, whereby the vacuum is replaced with an inert gas after the distillation is complete. However, this is a less satisfactory system if one desires to collect fractions under a reduced pressure. To do this a "pig" adaptor can be added to the end of the condenser, or for better results or for very air sensitive compounds a Perkin triangle apparatus can be used. A Perkin triangle is a piece of specialist Distillation apparatus

The Perkin triangle, has means via a series of glass or Teflon taps to allows fractions to be isolated from the rest of the still, without the main body of the distillation being removed from either the vacuum or heat source, and thus can remain in a state of reflux. In Chemistry, poly(tetrafluoroethene or poly(tetrafluoroethylene ( PTFE) is a synthetic Fluoropolymer which finds numerous applications A still is an apparatus used to distill Miscible or immiscible (eg This article is about using reflux in chemical engineering and chemistry To do this, the sample is first isolated from the vacuum by means of the taps, the vacuum over the sample is then replaced with an inert gas (such as nitrogen or argon) and can then be stoppered and removed. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 This article pertains to the chemical element For other uses see Argon (disambiguation. A fresh collection vessel can then be added to the system, evacuated and linked back into the distillation system via the taps to collect a second fraction, and so on, until all fractions have been collected.

Short path distillation

Short path vacuum distillation apparatus with vertical condenser (cold finger), to minimize the distillation path; 1: Still pot with stirrer bar/anti-bumping granules 2: Cold finger - bent to direct condensate 3: Cooling water out 4: cooling water in 5: Vacuum/gas inlet 6: Distillate flask/Distillate.

Short path distillation is a distillation technique that involves the distillate traveling a short distance, often only a few centimeters. A centimetre ( American spelling: centimeter, symbol cm) is a unit of Length in the Metric system, equal to one hundredth A classic example would be a distillation involving the distillate traveling from one glass bulb to another, without the need for a condenser separating the two chambers. This technique is often used for compounds which are unstable at high temperatures. The Advantage is that the heating temperature can be considerably lower (at this reduced pressure) than the boiling point of the liquid at standard pressure, and that the distillate only has to travel a short distance before condensing. A Kugelrohr apparatus can be used for Short path distillation. A Kugelrohr ( German for "ball tube" is a short-path Vacuum distillation apparatus typically used to distill relatively small amounts of compounds

Other types

• In rotary evaporation a vacuum distillation apparatus is used to remove bulk solvents from a sample. A rotary evaporator (or rotavap) is a device used in Chemical laboratories for the efficient and gentle removal of Solvents from samples by Evaporation A solvent is a liquid or gas that dissolves a solid liquid or gaseous Solute, resulting in a Solution. Typically the vacuum is generated by a water aspirator or a membrane pump. An aspirator, also called an Eductor-jet pump or filter pump is a device that produces Vacuum by means of the Venturi effect. A diaphragm pump is a positive displacement pump that uses a combination of the reciprocating action of a Rubber, Thermoplastic or teflon
• 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. A Kugelrohr ( German for "ball tube" is a short-path Vacuum distillation apparatus typically used to distill relatively small amounts of 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. Reactive distillation is a process where the chemical Reactor is also 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. Destructive distillation is the process of Pyrolysis conducted in a distillation apparatus ( Retort) to allow the volatile products to be collected For the biological process see Decomposition. For chemical decomposition in general see Chemical decomposition. 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. Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound
• Pervaporation is a method for the separation of mixtures of liquids by partial vaporization through a non-porous membrane. Pervaporation is a method for the Separation of mixtures of liquids by partial Vaporization through a non-porous or porous membrane. An artificial membrane, also called a synthetic membrane, is a membrane prepared for separation tasks in Laboratory and industry
• 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. Dry distillation is the Heating of Solid materials to produce Liquid or Gaseous products (which may condense into solids Pyrolysis is the Chemical decomposition of organic materials by heating in the absence of Oxygen or any other reagents except possibly Steam Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state
• 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. Extractive distillation is defined as Distillation in the presence of a Miscible, high boiling relatively Non-volatile component the Solvent
• 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. Flash (or partial Evaporation is the partial Vaporization that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through For other uses see Valve (disambiguation. For the electronic component see Thermionic valve. This process is one of the simplest unit operations.
• Freeze distillation is an analogous method of purification using freezing instead of evaporation. Fractional freezing is a process used in Process engineering and Chemistry to separate two liquids with different melting points For freezing as a method of food preservation see Frozen food. 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. American-style lager beer is a common variety of beer a type of Pale lager, traditionally made and consumed in North America but also popular in much of the rest of the world Ice wine (or icewine, as one word or in German, Eiswein) is a type of Dessert wine produced from Grapes that have been frozen while Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose.
• Codistillation is distillation which is performed on mixtures in which the two compounds are not miscible.

Azeotropic distillation

Main article: Azeotropic distillation

Interactions between the components of the solution create properties unique to the solution, as most processes entail nonideal mixtures, where Raoult's law does not hold. In Chemistry, azeotropic distillation is any of a range of techniques used to break an Azeotrope in Distillation. Established by François-Marie Raoult, Raoult's law states the Vapor pressure of an Ideal solution is dependent on the vapor pressure of each Such interactions can result in a constant-boiling azeotrope which behaves as if it were a pure compound (i. An azeotrope (pronounced e. , boils at a single temperature instead of a range). At an azeotrope, the solution contains the given component in the same proportion as the vapor, so that evaporation does not change the purity, and distillation does not effect separation. For example, ethyl alcohol and water form an azeotrope of 95. Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as 6% at 78. 1 °C.

If the azeotrope is not considered sufficiently pure for use, there exist some techniques to break the azeotrope to give a pure distillate. This set of techniques are known as azeotropic distillation. Some techniques achieve this by "jumping" over the azeotropic composition (by adding an additional component to create a new azeotrope, or by varying the pressure). Others work by chemically or physically remove or sequester the impurity. For example, to purify ethanol beyond 95%, a drying agent or a desiccant such as potassium carbonate can be added to convert the soluble water into insoluble water of crystallization. A Desiccant is a Hygroscopic substance that induces or sustains a state of dryness ( Desiccation) in its local vicinity in a moderately-well sealed container Carbonate of potash redirects here For one of potassium carbonate's impure forms see Potash. Water of crystallization (alt BrE water of crystallisation is Water that occurs in Crystals but is not covalently bonded to a host Molecule Molecular sieves are often used for this purpose as well. A molecular sieve is a material containing tiny pores of a precise and uniform size that is used as an adsorbent for Gases and Liquids Molecules

Immiscible liquids, such as water and toluene, easily form azeotropes. Commonly, these azeotropes are referred to as a low boiling azeotrope because the boiling point of the azeotrope is lower than the boiling point of either pure component. The temperature and composition of the azeotrope is easily predicted from the vapor pressure of the pure components, without use of Raoult's law. The azeotrope is easily broken in a distillation set-up by using a liquid-liquid separator ( a decanter ) to separate the two liquid layers that are condensed overhead. Only one of the two liquid layers is refluxed to the distillation set-up.

High boiling azeotropes, such as a 20 weight percent mixture of hydrochloric acid in water also exist. As implied by the name, the boiling point of the azeotrope is greater than the boiling point of either pure component.

To break azeotropic distillations and cross distillation boundaries, such as in the DeRosier Problem, it is necessary to increase the composition of the light key in the distillate.

Breaking an azeotrope with unidirectional pressure manipulation

A vacuum distillation can be used to "break" an azeotropic mixture. Varying the temperature of the vapour generating flask when distilling an azeotrope from cold to the solutions boiling point does not produce a continuously sliding ratio of product to contaminate in the distillate. The two separate boiling points still remain, they merely overlap; these can be thought of as required activation energies for the release of a particular vapour. By exposing an azeotrope to a vacuum, it's possible to bias the boiling point of one away from the other by exploiting the difference between each components vapour pressure. When the bias is great enough, the two boiling points no longer overlap and so the azeotropic band disappears.

This method is not without drawbacks. As an example, exposing a solution of water and ethanol to a 70 torr vacuum will allow for absolute ethanol to be distilled. However, due to the low pressure atmosphere, the ethanol vapour requires a significantly cooler condenser surface to liquefy, going from 78. 3 °C at atmospheric pressure to 24. 5 °C at 70 torr; failure to provide such results in the vapours passing through the condenser and into the vacuum source. This can also affect the efficiency of the condenser, as the liquefying temperature drops towards the minimum the condensing equipment can cool to, the thermal gradient across the liquefying surfaces reduces and, so with it, the rate at which heat can be extracted from the vapour.

Conversely, increasing a distillation pressure can also break an azeotrope, but will bring with it the possibility of thermal decomposition, for organic compounds in particular, and may be more beneficial to high temperature tolerant distillations, such as those of the metallic salts.

Pressure-swing Distillation

This method of distillation can be used to separate azeotropic mixtures and relies on a principle similar to vacuum distillation, that being the manipulation of boiling points by altering the pressure of the atmosphere to which a solution is exposed.

It might be chosen over pure vacuum distillation of an azeotrope if that solution, for instance, had such a low liquefying point at the pressure required to break the azeotrope that the equipment was unable to provide for it, allowing the product to stream out of the condenser and into the vacuum source. Here, rather than manipulate just one boiling point, one or more are altered, one after the other; with the number of pressure alternations being determined by the number of components in the feed solution considered to be contaminants. This could be beneficial to a purification as it is likely to create less extreme thermal requirements. Simply, instead of swinging distillation pressure in one direction alone in an attempt to break the azeotrope in one step, the break is performed in two or more steps with pressure swung in two directions to create an operating band centered around more accessible temperatures; perhaps going from a negative pressure to atmospheric and on to a positive pressure. In essence, pressure-swing distillation is an attempt to reduce extreme conditions by dispersing the manipulation load across the equipment generating the distillation environment.

If a continuous feed is desired, or the distillation pressures required are extreme enough to warrant specialised design, each step may require a physically separate column. If only a batch run is required and the same column can perform under all the required pressures, this single column may suffice; with the vapour generating flask being emptied after the first distillation, the first distillate run back to the start and the distillation rerun under the second pressure conditions, and so on.

Selection of which component the distillate should be biased towards may be made based on the energy required to evaporate it from the feed solution.

Pressure-swing distillation is employed during the purification of ethyl acetate after its catalytic synthesis from ethanol. Ethyl acetate ( systematically, ethyl ethanoate commonly abbreviated EtOAc or EA is the Organic compound with the formula CH3COOCH2CH3

Industrial distillation

Typical industrial distillation towers

Main article: Continuous distillation

Large scale industrial distillation applications include both batch and continuous fractional, vacuum, azeotropic, extractive, and steam distillation. Continuous distillation, a form of Distillation, is an ongoing separation in which a mixture is continuously (without interruption fed into the process and separated fractions The most widely used industrial applications of continuous, steady-state fractional distillation are in petroleum refineries, petrochemical and chemical plants and natural gas processing plants. An oil refinery is an industrial Process plant where Crude oil is processed and refined into more useful Petroleum products, such as Gasoline Petrochemicals are chemical products made from raw materials of Petroleum or other Hydrocarbon origin A chemical plant is industrial process plant that manufactures (or otherwise processes Chemicals usually on a large scale Natural gas processing plants or fractionators are used to purify the raw Natural gas extracted from underground gas fields and brought up to the surface by

Industrial distillation^[24][25] is typically performed in large, vertical cylindrical columns known as distillation towers or distillation columns with diameters ranging from about 65 centimeters to 16 meters and heights ranging from about 6 meters to 90 meters or more. When the process feed has a diverse composition, as in distilling crude oil, liquid outlets at intervals up the column allow for the withdrawal of different fractions or products having different boiling points or boiling ranges. Petroleum ( L petroleum, from Greek πετρέλαιον, lit The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid The "lightest" products (those with the lowest boiling point) exit from the top of the columns and the "heaviest" products (those with the highest boiling point) exit from the bottom of the column and are often called the bottoms.

Diagram of a typical industrial distillation tower

Large-scale industrial towers use reflux to achieve a more complete separation of products. This article is about using reflux in chemical engineering and chemistry Reflux refers to the portion of the condensed overhead liquid product from a distillation or fractionation tower that is returned to the upper part of the tower as shown in the schematic diagram of a typical, large-scale industrial distillation tower. Inside the tower, the downflowing reflux liquid provides cooling and condensation of the upflowing vapors thereby increasing the efficacy of the distillation tower. The more reflux is provided for a given number of theoretical plates, the better is the tower's separation of lower boiling materials from higher boiling materials. A theoretical plate in many Separation processes is a hypothetical zone or stage in which two phases such as the Liquid and Vapor phases of a substance Alternatively, the more reflux is provided for a given desired separation, the fewer theoretical plates are required.

Such industrial fractionating towers are also used in air separation, producing liquid oxygen, liquid nitrogen, and high purity argon. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Liquid nitrogen (liquid density at the Triple point is 0707 g/mL is the liquid produced industrially in large quantities by Fractional distillation of This article pertains to the chemical element For other uses see Argon (disambiguation. Distillation of chlorosilanes also enables the production of high-purity silicon for use as a semiconductor. Chlorosilanes are a group of reactive Chlorine -containing Chemical compounds related to Silane and used in many chemical processes Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that

Section of an industrial distillation tower showing detail of trays with bubble caps

Design and operation of a distillation tower depends on the feed and desired products. Given a simple, binary component feed, analytical methods such as the McCabe-Thiele method^[25][26] or the Fenske equation^[25] can be used. The graphical approach presented by McCabe and Thiele in 1925 the McCabe-Thiele method is considered the simplest and perhaps most instructive method for analysis of binary Distillation The Fenske equation in continuous Fractional distillation is an Equation used for calculating the minimum number of theoretical plates required for the For a multi-component feed, simulation models are used both for design and operation. Simulation is the imitation of some real thing state of affairs or process Moreover, the efficiencies of the vapor-liquid contact devices (referred to as "plates" or "trays") used in distillation towers are typically lower than that of a theoretical 100% efficient equilibrium stage. A theoretical plate in many Separation processes is a hypothetical zone or stage in which two phases such as the Liquid and Vapor phases of a substance Hence, a distillation tower needs more trays than the number of theoretical vapor-liquid equilibrium stages.

In industrial uses, sometimes a packing material is used in the column instead of trays, especially when low pressure drops across the column are required, as when operating under vacuum.

Large-scale, industrial vacuum distillation column^[27]

This packing material can either be random dumped packing (1-3" wide) such as Raschig rings or structured sheet metal. Raschig rings are pieces of tube (approximately equal in length and diameter used in large numbers as a Packed bed within columns for distillations and other The term structured packing refers to a range of specially designed materials for use in Absorption and Distillation columns and Chemical reactors Liquids tend to wet the surface of the packing and the vapors pass across this wetted surface, where mass transfer takes place. Mass transfer is the phrase commonly used in engineering for physical processes that involve molecular and convective transport of Atoms and Molecules Unlike conventional tray distillation in which every tray represents a separate point of vapor-liquid equilibrium, the vapor-liquid equilibrium curve in a packed column is continuous. However, when modeling packed columns, it is useful to compute a number of "theoretical stages" to denote the separation efficiency of the packed column with respect to more traditional trays. Differently shaped packings have different surface areas and void space between packings. Both of these factors affect packing performance.

Another factor in addition to the packing shape and surface area that affects the performance of random or structured packing is the liquid and vapor distribution entering the packed bed. The number of theoretical stages required to make a given separation is calculated using a specific vapor to liquid ratio. A theoretical plate in many Separation processes is a hypothetical zone or stage in which two phases such as the Liquid and Vapor phases of a substance If the liquid and vapor are not evenly distributed across the superficial tower area as it enters the packed bed, the liquid to vapor ratio will not be correct in the packed bed and the required separation will not be achieved. The packing will appear to not be working properly. The height equivalent of a theoretical plate (HETP) will be greater than expected. A theoretical plate in many Separation processes is a hypothetical zone or stage in which two phases such as the Liquid and Vapor phases of a substance The problem is not the packing itself but the mal-distribution of the fluids entering the packed bed. Liquid mal-distribution is more frequently the problem than vapor. The design of the liquid distributors used to introduce the feed and reflux to a packed bed is critical to making the packing perform to it maximum efficiency. Methods of evaluating the effectiveness of a liquid distributor to evenly distribute the liquid entering a packed bed can be found in references. ^[28][29] Considerable work as been done on this topic by Fractionation Research, Inc. (commonly known as FRI). ^[30]

Distillation in food processing

Distilled beverages

Main article: Distilled beverage

Carbohydrate-containing plant materials are allowed to ferment, producing a dilute solution of ethanol in the process. Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most Spirits such as whiskey and rum are prepared by distilling these dilute solutions of ethanol. Whisky (uisge-beatha or whiskey (uisce beatha or fuisce) refers to a broad category of Alcoholic beverages that are distilled from fermented Rum is a Distilled beverage made from Sugarcane by-products such as Molasses and sugarcane Juice by a process of fermentation Other components than ethanol are collected in the condensate, including water, esters, and other alcohols which account for the flavor of the beverage.

References

Further reading

• Forbes, R. J. (1970). A Short History of the Art of Distillation from the Beginnings up to the Death of Cellier Blumenthal. BRILL. ISBN 9004006176.  
• Needham, Joseph (1954). Science and Civilisation in China (vol. 4) Cambridge University Press: ISBN 052108573X
• Allchin, F. R. (Mar. , 1979). India: The Ancient Home of Distillation?. Man, New Series, Vol. 14, No. 1 , pp. 55-63. Royal Anthropological Institute of Great Britain and Ireland.

External links

• Alcohol distillation
• Introduction to Distillation, University of Newcastle upon Tyne, UK
• American Distilling Institute
• Essential and Fragrance Oils Distillation
• Extractive Distillation
• Pharmaceutical Alcohol Distillation
• Distillation - Food Applications
• Case Study: Petroleum Distillation
• Binary Vapor-Liquid Equilibrium Data (searchable database). Chemical Engineering Research Information Center. Retrieved on 5 May 2007.

Gallery

	Chemistry on its beginnings used retorts as laboratory equipment exclusively for distillation processes. In a Chemistry laboratory a retort is a glassware device used for Distillation or Dry distillation of substances Laboratory equipment refers to the various Tools and Equipment used by Scientists working in a Laboratory.
	A simple set-up to distill dry and oxygen-free toluene. Toluene, also known as methylbenzene or phenylmethane, is a clear water -insoluble liquid with the typical smell of Paint thinners redolent of
	Diagram of an industrial-scale vacuum distillation column as commonly used in oil refineries
	A rotary evaporator is able to distill solvents more quickly at lower temperatures through the use of a vacuum. An oil refinery is an industrial Process plant where Crude oil is processed and refined into more useful Petroleum products, such as Gasoline A rotary evaporator (or rotavap) is a device used in Chemical laboratories for the efficient and gentle removal of Solvents from samples by Evaporation This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner.
	Distillation using semi-microscale apparatus. The jointless design eliminates the need to fit pieces together. The pear-shaped flask allows the last drop of residue to be removed, compared with a similarly-sized round-bottom flask The small holdup volume prevents losses. Round-bottom flasks (also called round-bottomed flasks and Erlenmeyer Bulbs) are types of Flasks having spherical bottoms used as Laboratory glassware A pig is used to channel the various distillates into three receiving flasks. If necessary the distillation can be carried out under vacuum using the vacuum adapter at the pig.