Middle-Stream of Petrochemical Industries

Middle-Stream of Petrochemical Industries



Stephanus Sulaeman@upv.pertamina


8. PETROCHEMICALS FROM ETHYLENE

Ethylene is a prime raw material for petrochemicals and it is readily available at low cost and high purity. Ethylene reacts by addition with low cost materials such as oxygen, chlorine, hydrogen chloride and water, and the reaction take place under relatively mild condition and usually with high yields. Ethylene also reacts by substitution to producevinyl monomer. Derivatives of ethylene are used for the production of plastics, antifreeze, fibers and solvents. Ethylene and many ethylene derivatives are used for the production of polymers, like the formation of polyethylene and ethylene related polymer such as polystyrene, polyester and polyvinyl chloride. Ethylene oxides dominates the individual compounds produced fromethlene with ethylene dichloride, the precursor of vinyl chloride, next in quantity of ethylene utilized followed by ethyl benzene for styrene production. While polyethylene is the biggest individual compounds produced from ethylene and the others are ethanol, linear alcohol, vinyl acetate, alpha olefins and many others. The projected use for ethylene is mainly in low density polyethylene, high density polyethylene, vinyl chloride, styrene, ethylene oxide and others.

8.1. ETHYLENE OXIDE EO CH2-O-CH2

Production.

EO is produced by exothermic by air or oxygen oxidation of gas phase ethylene over a silver Ag2O catalyst in a very short time (second).

2 CH2=CH2 + O2 → 2 CH2-O-CH2

The concominant exothermic reaction is

CH2=CH2 + 3 O2 → 2 CO2 + 2 H2O

Ethylene oxide selectivity is improved when the reaction temperature lowered and the conversion of ethylene is decreased. The use of high selectivity catalyst and control of temperature are key factors in succesful production of ethylene oxide. The development of high selectivity catalyst is obtained by incorporating alkali metal cations in, on or under the silver particles on the alumina. All of Shell, Halcon and ICI patented this kind of high selectivity compound catalyst. There are many representative process for both ethylene oxide and ethylene glycol production.

With air oxidation the reaction is carried out in single stage main reactor. The oxidation reaction is controlled in a manner similar to that used for air oxidation. Most of the absorber outlet gas is recycled to the reactor and the rest is treated by potassium hydroxide solution to remove CO2 and the recycled again to the reactor. The oxygen process is approximately more economical than the air process.

Uses.

Ethylene oxide reacts exothermically, especially in the presence of catalyst, with all compounds which have a labile hydrogen atom, such as water, alcohols, amines and organic acids. This reaction introduces the hydroxyethyl group –CH2-CH2OH into various type of compounds, like

R-CH2OH + CH2-O-CH2 → R-CH2O-CH2-CH2OH

The addition of the hydroxyethyl group increases the water solubility of the resulting compounds. Further reaction with ethylene oxide produces polyethylene oxide derivatives. The number of moles of ethylene oxide determine the water solubility and the surface activity of the product.

The uses of ethylene oxide demanded mainly are ethylene glycol and surfactants. Ethylene glycol is mainly used for antifreeze and polyester, and there are two major types of surfactants, alkyl phenol ethoxylates non-biodegradable or hard surfactants and linear alcohol ethoxylates biodegradable or soft surfactants. Other compounds from EO are the higher glycols, glycol ethers and the ethanolamines, and less important product are tertiary alkyl mercaptoalcohols, glycol acetate and diacetate, beta phenyl ethyl alcohol and hydroxyethyl cellulose. Ethylene oxide is also used as a cold sterilant for bacteria, spores and viruses and with CO2 for controlling wievils in nuts. It is an effective insecticide and its also used as an intermediate for other insecticides as well as for fungicides, explosives and resins.

8.1.1. Ethylene glycol EG HOCH2-CH2OH

EG is essentially produced by the hydration of ethylene oxide. It also can be produced directly from ethylene by acetoxylation - the Oxirane process, or oxychlorination – the Teijin process. The other process to produce EG is from syn-gas by direct synthesis process.

From ethylene oxide.

The oxide ring, epoxide ring, is readily opened by water in the presence of hydrogen ions (0.5 – 1% H2SO4 catalyst).

CH2-O-CH2 + H2O H+→ HOCH2-CH2OH

This is a liquid phase process where di- and triethylene glycol ethers are formed, which is not an economics burden on the monoglycol. They have many applications with the most important being water based coatings. The tri-ethers are paramount in the brake fluid market.

From ethylene by acetoxylation.

The production of EG is carried out in two steps. The first step is the catalyzed liquid phase oxidation of ethylene in acetic acid to a mixture of mono and diacetates of ethylene glycol over TeO2 (promoted by Br compounds) catalyst.

2 CH2=CH2 + 3 CH3-C=O OH + O2 →

CH3-C=O OCH2-CH2OH + CH3-C=O OCH2-CH2O-C=O CH3 + H2O

The acetates are hydrolyzed to obtain the glycol and regenerate acetic acid for reuse.

CH3-C=O OCH2-CH2OH + CH3-C=O OCH2-CH2O-C=O CH3 + 3 H2O →

2 HOCH2-CH2OH + 3 CH3-C=O OH

The net reaction 2 CH2=CH2 + 2 H2O + O2 → 2 HOCH2-CH2OH

Manganese acetate catalyst plus potassium iodide has also been used widely.

The acetates are hydrolyzed to ethylene glycol, but it is difficult to complete and with the separation of the monoacetals and glycols, hard to accomplish. Ethylene efficiency improvement can be secured by the Oxirane process but it require higher investment and energy cost. Corrosion is the major production problem with the Oxirane process, because of the presence of acetic and formic acids. Mean while the tellurium catalyst having a tendency to convert to the metal and plate out.

From ethylene by oxychlorination.

The Teijin catalytic oxychlorination process is a modern chlorohydrin process for ethylene oxide production. In place of chlorine, concentrate 1N hydrochloric acid is used and thalium (III) chloride TlCl3 is the catalyst. The ethylene chlorohydrin may be hydrolyzed in-situ.

CH2=CH2 + TlCl3 + H2O → ClCH2-CH2OH + TlCl + HCl

ClCH2-CH2OH + H2O → HOCH2-CH2OH + HCl

The TlCl catalyst is regenerated by air or oxygen plus copper (II) chloride which gives the Thallium (III) chloride the status of the catalyst.

TlCl + 2 CuCl2 → TlCl3 + Cu2Cl2

Cu2Cl2 + 4 HCl + O2 → 4 CuCl2 + 2 H2O

The overall reaction is 2 CH2=CH2 + O2 + 2 H2O → 2 HOCH2-CH2OH

The by-products are acetaldehyde, dioxane and diethylene glycol. The acetaldehyde yield will be increases appreciably if the Cl : Ti3+ ratio is less than 4 : 1. When the reaction temperature is above 120 oC, the chlorohydrin is hydrolyzed in situ.

From formaldehyde and carbon monoxide and from synthesis gas.

The reaction of formaldehyde with carbon monoxide and water forms glycolyc acid.

H-C=O H + CO + H2O → HOCH2-C=O OH

The glycolyc acid is esterified with methanol.

HOCH2-C=O OH + CH3OH → HOCH2-C=O OCH3 + H2O

The ester is hydrogenated to ethylene glycol and methanol.

HOCH2-C=O OCH3 + 2 H2 → HOCH2-CH2OH + CH3OH

The net reaction is H-C=O H + CO + 2 H2 → HOCH2-CH2OH

Uses.

Ethylene glycol is used as antifreeze and polyester.

8.1.2. Ethanol amines (HOCH2-CH2)xN3-x

Monoethanol amine MEA HOCH2-CH2NH2, diethanol amine DEA (HOCH2-CH2)2NH and triethanol amine TEA (HOCH2-CH2)3N are produced as a mixture from the reaction of ethylene oxide with 25 to 50% aqueous ammonia.

CH2-O-CH2 + NH3 → HOCH2-CH2NH2

CH2-O-CH2 + (HOCH2-CH2)2NH → (HOCH2-CH2)3N

Ammonia : ethylene oxide ratio is 10 : 1

The relative proportions of mono, di and triethanolamine is dependent upon the ratio of ammonia to ethylene oxide. The ratio also varies with the temperature and pressure. Ethylene oxide / ammonia / recycle MEA feed ratios are used to control the distribution of ethanol amines to accomodate varying market demands for each of the products.

Uses.

The ethanol amines have unusually diverse industrial applications. The most important direct use for the ethanol amines is the sweetening of acid gases. The most important indirect use is for the production of detergents. The ethanol amines are also used as corrosion inhibitors and to stabilize chlorinated hydrocarbons by preventing decomposition in the presence of a metal or metallic compounds. The ethanol amines are used extensively for the production of ethanolamide detergents from fatty acids.

R-C=O OH + HOCH2-CH2NH2 → R-C=ONH-CH2-CH2OH + H2O

Lauric acid CH3-(CH2)10-C=O OH is the main fatty acid used. Monoethanol amides are used primarily in heavy duty powder detergents as from stabilizers, corrosion inhibitors and rinse improvers. Ethanol amines soaps rank close behind the ethanolamides as important industrial products. They are formed by reaction of an ethanol amine with a fatty acid, a reaction similar to the formation of ethanol amide, but at lower temperature and without catalyst. the product is a salt rather than an amide. The fatty acid utilized are oleic, stearic and palmitic. These soaps are used extensively in cosmetic preparation. Ethanol amine soaps are also used in soluble lubricating and cutting oils, furniture, automobile and metal polishes, solvent cleaners, stain and paint removers and spotting soaps, and floor, rug, woodwork and paintbrush cleaners.

8.2. VINYL CHLORIDE VCM CH2=CHCl

Production.

VCM is produced by the balance oxychlorination process in three principal process steps conversion of ethylene and chlorine.

The first step is direct chlorination by exothermic reaction of liquid or vapor phase addition of chlorine to ethylene to produce ethylene dichloride EDC over ethylene bromide or iron chloride FeCl3 catalyst.

CH2=CH2 + Cl2 → ClCH2-CH2Cl

The second step is pyrolysis of EDC to VCM and hydrogen chloride HCl over pumice or charcoal catalyst.

ClCH2-CH2Cl → CH2=CHCl + HCl

The third step is oxychlorination in which the pyrolysis HCl, ethylene and oxygen in the presence of modified Deacon type catalyst combine to form EDC and water on fluidized bed or fixed bed reactor.

2 CH2=CH2 + 4 HCl + O2 → 2 ClCH2-CH2Cl + 2 H2O

The EDC is recycled to the pyrolysis unit. The overall reaction is

4 CH2=CH2 + 2 Cl2 + O2 → 4 CH2=CHCl + 2 H2O

The oxychlorination step is the heart of the process and has two major variants – reactor and oxidant. Either a fluidized bed or fixed bed reactor is used – along with either oxygen or air.

Oxychlorination is an effective way to utilize the by product hydrogen chloride, but it is also the most costly process step. Many of the chlorinated compounds which have to be removed in the distillation section are by-products of the oxychlorination step. An integrated process eliminates some of these problems because the oxychlorination step is separate from the chlorine-ethylene addition step. In this particular process the oxidation of hydrogen chloride is catalyzed by nitrogen oxide in a circulating stream of sulfuric acid – the KeChlor process.

Uses.

The VCM is used for the production of homo and copolymers. Their major uses are for extrusion such as pipe, films, coatings and moldings. The relationship between capacity and demand are both increasing, but demand is less than the capacity. The major uses of Ethylene dichloride is for the production of vinyl chloride, the minor is used as chlorinated solvent, the remainder is used as a lead scavengers.

8.3. ETHYLBENZENE C6H5-CH2-CH3

Production.

Ethyl benzene is produced by alkylation reaction between benzene and ethylene over AlCl3 catalyst for liquid phase and crystalline alumino-silicate zeolite catalyst for vapour phase.

C6H6 + CH2=CH2 → C6H5-CH2-CH3

Uses.

Ethyl benzene is mainly used to produce styrene C6H5-CH=CH2 by endothermic vapor phase, Fe-Cr oxide catalytic dehydrogenation.

C6H5-CH2-CH3 → C6H5-CH=CH2 + H2

8.4. ETHANOL CH3-CH2OH

Production.

Ethyl alcohol are produce by fermentation or indirect hydration of ethylene with mono- and diethyl sulfates as intermediate and direct hydration of ethylene. The synthetic indirect hydration of ethylene is

3 CH2=CH2 + 2 H2SO4 → CH3-CH2OSO3H + (CH3-CH2O)2SO2

Hydrolysis of these sulfate gave ethanol and regenerated the sulfuric acid.

CH3-CH2OSO3H + (CH3-CH2O)2SO2 + 3 H2O → 3 CH3-CH2OH + 2 H2SO4

The synthetic direct hydration of ethylene is over H3PO4 on diatomaceous earth catalyst or Al(OH)3 gel and tungstic acid on silica gel.

CH2=CH2 + H2O → CH3-CH2OH

The initial product is 94 - 95% ethanol which can be dehydrated to anhydrous ethanol.

Uses.

Ethanol is used as solvent and chemical conversion uses. Compound synthesized from ethanol are ethyl chloride, ethyl ether, glycol ethyl ether, ethyl vinyl ether, chloral, ethyl amines, ethyl mercaptan, acetic acid and many different ethyl esters.

8.5. ACETALDEHYDE CH3-C=O H

Production.

The production of acetaldehyde firstly was by the silver catalyzed oxidation of ethanol or by the chromium activated copper catalyzed dehydration of ethanol. The more sophisticated process used a combination of oxidation-dehydrogenation. The exothermic oxidation provided the heat required for the endothermic dehydrogenation.

Oxidation 2 CH3-CH2OH + O2 → 2 CH3-C=O H + H2O

Dehydrogenation CH3-CH2OH → 2 CH3-C=O H + H2

Currently acetaldehyde is produced directly from ethylene by use of a liquid phase homogenous catalyst. One distinct advantage of this catalyst is high selectivity, a significant energy saving because of the low temperatures and pressure of the operating condition.

The homogenous catalyst system used for the oxidation of ethylene to acetaldehyde consist of an aqueous solution of copper (II) chloride CuCl2, and a small quantity of palladium (II) chloride PdCl2. In the course of oxidation, the palladium ion of PdCl2 is reduced to metallic palladium.

CH2=CH2 + H2O + PdCl2 → CH3-C=O H + 2 HCl + Pd

The palladium is reoxidized to palladium (II) ion (Pd2+) by the copper (II) ion (Cu2+) which becomes copper (I) ion (Cu+).

Pd + 2 CuCl2 → PdCl2 + 2 CuCl

The copper (I) ion is reoxidized to copper (II) ion, by air or oxygen.

2 CuCl + ½ O2 + 2 HCl → 2 CuCl2 + H2O

The overall reaction is exothermic reaction over PdCl2/CuCl2 catalyst.

2 CH2=CH2 + O2 → 2 CH3-C=O H

The oxidation is carried out as a single stage process over PdCl2/CuCl2 catalyst with the oxygen used in situ to regenerate the copper (II) ion. In the two stage process over PdCl2/CuCl2 catalyst also, the catalyst solution, containing copper (I) ion equivalent to the amount of acetaldehyde formed, is transferred into a tube oxidizer and reoxidized with air. Acetaldehyde can be produced by the vapour phase catalytic oxidation of ethylene over Pd/V2O5/Ru on Al2O3 catalyst.

CH2=CH2 + O2 + H2O → CH3-C=O H + CH3-C=O OH

The by-product acetic acid is not an economic burden because acetaldehyde is use as one of the precursor of acetic acid.

Acetaldehyde is also produced by the non-catalytic oxidation of propane, butane or a mixture of two. The by-products are formaldehyde, methanol and other.

Uses.

Acetaldehyde is used to synthesize other compounds, which are acetic acid, peracetic acid, acetic anhydride, chloral, paraldehyde, polyacetaldehyde, n-butyraldehyde, n-butanol and pentaerythritol. Acetic acid is obtained by the liquid phase oxidation of acetaldehyde over (CH3-C=O)2Mn.

2 CH3-C=O H + O2 → 2 CH3-C=O OH

Acetic acid is also produced by the liquid phase oxidation of n-butane and naphtha, and by methanol carbonylation. n-butanol CH3-CH2-CH2-CH2OH is produced by the Aldol condensation of acetaldehyde with the intermediate formation of crotonaldehyde CH3-CH=CH-C=O H, which is hydrogenated to n-butanol.

2 CH3-C=O H (OH-)→ CH3-CHOH-CH2-C=O H

CH3-CHOH-CH2-C=O H H+→ CH3-CH=CH-C=O H + H2O

CH3-CH=CH-C=O H + H2 → CH3-CH2-CH2-CH2OH

n-butanol is also produced from propylene by the Oxo process (catalytic hydroformylation of propylene with carbon monoxide and hydrogen, followed by hydrogenation)

2 CH3-CH=CH2 + 2 CO + 2 H2 → CH3-CH2-CH2-C=O H + CH3 CH3-CH-C=O H

CH3-CH2-CH2-C=O H + H2 → CH3-CH2-CH2-CH2OH

8.6. VINYL ACETATE CH2=CHO-C=O CH3

Production.

Vinyl acetate is produced from ethylene and acetic acid by both liquid phase and vapor phase catalytic oxidation process. The liquid phase process is similar to homogeneous catalytic systems used for production acetaldehyde from ethylene, but the difference is the presence of acetic acid. CH2=CH2 + 2 CH3-C=O OH + O2 → CH2=CHO-C=O CH3 + CH3-C=O H + H2O

The liquid phase process is not used extensively because of corrosion problems and the formation of a fairly wide variety of other by products. The vapour phase process, over Pd on Al2O3 or SiO2/Al2O3 catalyst, is currently the most commercial

2 CH2=CH2 + 2 CH3-C=O OH + O2 → 2 CH2=CHO-C=O CH3 + 2 H2O

Another process which already obsolete is acetylene process. In this process the acetic acid adds to acetylene in the presence of mercury (II) acetate.

HC=CH + CH3-C=O OH → CH2=CHO-C=O CH3

Uses.

Vinyl acetate is a versatile monomer used to produce polyvinyl acetate and vinyl acetate copolymer, polyvinyl alcohol and other polymers.

8.7. ACRYLIC ACID CH2=CH-C=O OH

Production.

Acryic acid can be produced from ethylene by oxidative carbonylation with carbon monoxide and oxygen with a palladium (II)/copper (II) catalyst system. This is the same type of homogenous liquid phase catalytic reaction used to produce acetaldehyde from ethylene. The overall reaction over PdCl2/CuCl2 catalyst is

2 CH2=CH2 + 2 CO + O2 → 2 CH2=CH-C=O OH

This process can’t compete with the oxidation of propylene, with the intermediate is acrolein.

CH3-CH=CH2 + O2 → CH2=CH-C=O H + H2O

2 CH2=CH-C=O OH + O2 → 2 CH2=CH-C=O OH

Uses.

Acrylic acid and its esters are used to make acrylic fibres and plastics.

8.8. PROPIONALDEHYDE CH3-CH2-C=O H

Production.

Propionaldehyde is produced by the hydroformulation of ethylene with carbon monoxide and hydrogen, the Oxo reaction.

CH2=CH2 + 2 CO + H2 → CH3=CH2-C=O H

Cobalt carbonyl complexes have been used as the catalyst and high pressure and medium temperature are required, but currently it is replace by a complex of rhodium bonded by labile linkages to an organic ligand. During the reaction, CO and H2 also form a complex with the catalyst. The result is lower temperature and pressure. The construction cost is lower and so do the operating cost. Also higher yields and a purer products are obtained.

Uses.

Propionaldehyde is used to make other compounds such as propanol CH3-CH2-CH2OH and propionic acid CH3=CH2-C=O OH. Propionaldehyde is hydrogenated to propanol CH3-CH2-CH2OH,

CH3=CH2-C=O H + H2 → CH3-CH2-CH2OH

Various herbicide synthesis mainly used propanol. The large use is in solvents for coating and for ink used in printing on containers. Propionic acid CH3=CH2-C=O OH is obtained by oxidation from propionaldehyde.

CH3=CH2-C=O H + H2 → CH3=CH2-C=O OH

This compound is the largest user of propionaldehyde. Propionic acid is used as a preservative for grain, especially corn.

8.9. LINEAR ALCOHOLS CH3-(CH2)2-26-CH2OH

Production.

Linear alcohols are produced from ethylene by a four step process – the Alfol process. A Ziegler type catalyst is first produced by the reaction between aluminum metal, hydrogen and ethylene to form triethyl aluminum (CH3-CH2-)3Al.

Catalyst preparation.

6 CH2=CH2 + 2 Al + 3 H2 → 2 (CH3-CH2-)3Al

Polymerization over (CH3-CH2-)3Al ‘catalyst’,

CH3-(CH2-)x-CH2 )

n CH2=CH2 + (CH3-CH2-)3Al → CH3-(CH2-)y-CH2 > Al

CH3-(CH2-)z-CH2 )

Oxidation the trialkylaluminum with bone dry air to aluminum trialkoxides.

CH3-(CH2-)x-CH2 ) CH3-(CH2-)x-CH2-O )

2 CH3-(CH2-)y-CH2 > Al + 3 O2 → 2 CH3-(CH2-)y-CH2-O > Al

CH3-(CH2-)z-CH2 ) CH3-(CH2-)z-CH2-O )

Hydrolysis, the mixture of aluminum trialkoxides is hydrolyzed by concentrated sulfuric acid to yield a mixture of even numbered primary alcohols and aluminum sulfat.

CH3-(CH2-)x-CH2-O ) ( 2 CH3-(CH2-)x-CH2OH

2 CH3-(CH2-)y-CH2-O > Al + 3 H2SO4 → ( 2 CH3-(CH2-)y-CH2OH + Al2(SO4)3

CH3-(CH2-)z-CH2-O ) ( 2 CH3-(CH2-)z-CH2OH

The aluminum sulfate co-product from the hydrolysis is used in paper making and water treatment. Water is used in modified Alfol process instead of sulfuric acid to effect the hydrolysis, and the co-product is alumina Al2O3, used in the production of catalyst.

Uses.

Linear alcohols are biodegradable and those in the C12-16 range are used to make detergent, those in the C10-12 range are used to make plastizicers and the C16-18 alcohol are modifiers for wash and wear resins. The higher alcohols C20-26, are used as lubricants and mold release agents. Alpha olefins R-CH=CH2 are produced from trialkylaluminum by reaction with 1-butene.

[CH3-(CH2-)n]3Al + 3 CH3-CH2-CH=CH2 → 3 CH3-CH2-(CH2-)3n-9CH=CH2 + [CH3-(CH2-)3]3Al

The triethylaluminum and 1-butene are recoverd by reaction between tributylaluminum and ethylene.

[CH3-(CH2-)3]3Al + 3 CH2=CH2 → (CH3-CH2-)3Al + 3 CH3-CH2-CH=CH2

The alpha olefins are used in the production of detergents. Poly alpha olefins PAO, are used as industrial lubricants, hydraulic fluids, turbine and gear lubricants, multigrade grease and air compressor lubes. They conserve fuel by reducing friction and they have greater thermal stability to give longer service life.



9. PETROCHEMICALS FROM PROPYLENE AND HIGHER OLEFINS

Propylene CH3–CH=CH2 is always a by product, it comes as a by product of refinery operations and from steam cracking of ethane and naphtha for ethylene production. Chemical grade propylene produce alkylate and polymer gasoline components. Propylene is utilize to produce mainly poly-propylene, acrylic acid and others.

9.1. ACRYLONITRILE CH2=CH-CN

Production.

Acrylonitrile AN is produced by direct ammoxidation, oxidative amination of propylene.

2 CH3–CH=CH2 + 2 NH3 + 3 O2 → 2 CH2=CH-CN + 6 H2O

The reaction is exothermic and take place in fluidized bed with ‘catalyst 4I’ catalyst on once through basis under a short time residence time (in seconds). The by-product of this reaction is acetonitrile CH3-CN and hydrogen cyanide HCN. The heart of the process is the ammoxidation catalyst and the reactor. The Montedison – UOP fluidized bed process uses extremely active high performance catalyst which give a propylene conversion of over 95 % and acrylonitile selectivity is excess of 80 %. New catalyst had been developed by Nitto Chemical Industry Co. for Sohio process. Both fluid bed catalyst and fixed bed reactors are used. The British Petroleum and the Snamprogetti process use fixed bed reactors, but modern acrylonitrile processes use fluidized bed reactor.

Uses.

The major uses of acrylonitrile are in the production of plastics and resins. Acrylonitrile is converted to acrylamide CH2=CH-C=OOH, an essential aminoacid. The most potential reaction is the production of adiponitrile ADN NC-(CH2)4-CN by direct electrohydrodimerization of acrylonitrile.

Anode H2O – 2e- H+ → 2 CH2=CH-CN Cathode

↓ ↓ +2H+ + 2e-

½ O2 + 2 H+ H+ → NC-(CH2)4-CN

Anolyte Catholyte

The electrohydrodimerization take place on the cathode surface. Propionitrile, CH3-CH2-CN is a by-product. Adiponitrile is the precursor for nylon 66.

9.2. PROPYLENE OXIDE 1,2-epoxy propane CH3-CH-O-CH2

Propylene oxide is similar in structure to ethylene oxide, but it is markedly different in both production and uses. There are two major processes for the production of propylene oxide. The old one is chlorohydrination of propylene followed by epoxidation of the chlorohydrin by calcium hydroxide. The recent process is oxidation by use of an organic peroxide – the Oxirane process.

Propylene chlorohydrin process.

The chlorohydrination process consists of the formation of propylene chlorohydrin CH3-CHOH-CH2Cl, by the reaction between hypochlorous acid HOCL, and propylene. The hypochlorous acid is formed by the reaction between chlorine and water Cl2 + H2O → HOCL + HCl.

2 CH3–CH=CH2 + HOCl → CH3-CHOH-CH2Cl

The propylene chlorohydrin is epoxidized to propylene oxide by a 10 % solution of milk of lime Ca(OH)2.

2 CH3–CH=CH2 + Ca(OH)2 → CH3-CH-O-CH2 + CaCl2 + 2 H2O

The propylene oxide is removed by stripping with live steam.

Two disadvantages of the chlorohydrin process are first the chlorine is costly and it ends up as very weak calcium chloride solution, and secondly it is also necessary to dispose of 10 % to 15 % propylene dichloride.

Epoxidation by peroxides.

The production of propylene oxide by organic peroxides is also two step process, the main difference is that the co-products are compounds of appreciable economic value

The chemical reaction epoxidation of propylene by peracetic acid CH3-C=O OOH which is peroxide, is 2 CH3–CH=CH2 + CH3-C=O OOH → CH3-CH-O-CH2 + CH3-C=O OH

The peracetic acid is produced from acetaldehyde and air CH3-C=O H + O2 → CH3-C=O OOH.

The oxidation is carried out in an ethyl acetate solution and in the presence of a metal ion catalyst. The peracetic acid is obtained as a 30 % solution in ethyl acetate.

The Oxirane process uses either iso-butane hydroperoxide CH3 CH3-C-CH3 OOH or ethyl benzene hydroperoxide C6H5-CH-CH3 OOH. The hydroperoxides are formed by air oxidation of the feed stocks, and which feed-stock is used is determined of the co-product derrivative wanted, isobutylene or styrene. The epoxidation conditions using ethyl benzene hydroperoxide EBHP over Mo compounds catalyst such as coordination compounds of molybdenum hexacarbonyl and molybdenum oxyacetyl acetonate, or transition metal ions such as Mo, W, Cr and V.

Other methods.

Other epoxidizing agent is perisobutyric acid CH3 CH3-CH-C=O OOH obtained from isobutyric aldehyde. The co-product isobutyric acid is esterified and dehydrogenated to methyl metacrylates MMA.

Another process is use hydrogen peroxide to form a peracid in situ, which then epoxidizes the propylene. The co-product organic acid is recycled to be peroxidized again.

CH3–CH=CH2 + H2O2 → CH3-CH-O-CH2 + H2O

Hydrogen peroxide with arsenic compounds in dioxane at 90 °C will react directly with propylene to form propylene oxide. A similar arsenic catalyst with tetracyanoethylene (NC)2C=C(CN)2 and ethyl acetate CH3-CH2-C=O CH3 uses oxygen directly to epoxidize propylene

2 CH3–CH=CH2 + O2 → 2 CH3-CH-O-CH2.

Another two step route to propylene oxide is first propylene oxidized in liquid phase to the diol monoacetate in acetic acid

2 CH3–CH=CH2 + CH3-C=O OH + O2 → CH3-CH-OH CH2-OC=O CH3 + CH3-CH-CH2OHOC=O CH3.

The catalyst for the first step is PdCl2/LiNO3. In the second step the mixed acetates are pyrolyzed to propylene oxide and acetic acid over CH3-C=O OOK / Alundum catalyst and the acetic acid is recycled.

CH3-CH-OH CH2-OC=O CH3 + CH3-CH-CH2OHOC=O CH3 → CH3-CH-O-CH2 + 2 CH3-C=O OH.

The by-product propionaldehyde and acetone can be used.

Uses.

The major uses of propylene oxide are in the production of flexible foams and propylene glycol, while the others are for rigid foams, non-foams, dipropylene glycol, polypropylene glycol and isopropylamines.

Proppylene glycol CH3-CH-OH CH2OH is produced by the hydration of propylene oxide which is similar to the production of ethylene glycol from ethylene oxide. The glycol is used as an intermediate for unsaturated polyester resins and for softening of cellophane. Other uses include tobacco humectants, in cosmetics, brake fluids, as plasticizers and as additives.

Dipropylene glycol is consumed in the production of unsaturated polyester resins and plasticizers.

The iso-propylamines are produced and utilizes the same way as the ethanolamines.

Propylene carbonate CH3-CH-CH2-O-O-C=O is produced by the reaction between propylene oxide and carbon dioxide at 200 °C and 80 atm, used as a specialty solvent, as in the Fluor process for removing acid constituents from natural gas.

Allyl alcohol CH2=CH-CH2OH is produced by the isomeriztion of propylene oxide, it is the intermediate in a process for producing glycerol CH2OH-CHOH-CH2OH from propylene. The reaction is over Li3PO4 catalyst. CH3-CH-O-CH2 → CH2=CH-CH2OH.

The allyl alcohol is epoxidized to glycidol CH3-O-CH-CH2OH, which is hydrolized to glycerol (glycerin) CH2OH-CHOH-CH2OH

9.3. ISOPROPANOL, 2-propanol, isopropyl alcohol IPA, CH3-CHOH-CH3

Production.

Iso-propnaol is produced by sulfation of propylene followed by hydrolysis of the propylene sulfates. Another current process is direct-hydration of propylene to iso-propanol.

The Sulfation-Hydrolysis process consists of :

3 CH3–CH=CH2 + H2SO4 → CH3-CH-CH3 OSO3H + CH3-CH-CH3 OSO2O-CH-CH3 CH3.

Both iso-propyl hydrogen sulfate and diisopropyl sulfate are formed with the by-product is diisopropyl-ether CH3-CH-CH3 O CH3-CH-CH 3. The hydrolysis is effected by diluting the acid of the rreaction mixture to under 40 %.

CH3-CH-CH3 OSO3H + CH3-CH-CH3 OSO2O-CH-CH3 CH3 + 3 H2O → CH3-CHOH-CH3 + H2SO4

In the direct hydration process, the process use sulfonated polystyrene cation exchange resin catalyst.

CH3–CH=CH2 + H2O → CH3-CHOH-CH3.

The propylene is in supercritical state. The reactor is a fixed bed and propylene is flowing down a column of catalyst. Another hydrationcatalysts include polytungsten compounds in aqueous solutions and phosphoric acid on a solid carrier in addition to ion exchange resins.

Uses.

Minor uses of iso-propanol are the production of iso-propyl acetate CH3 O=C CH3-OCH-CH3, isopropyl amines, isopropyl xanthate CH3-CH-CH3 OC=S-SNa (a floating agent) and isopropyl myristate

CH3-(CH2)10-C=O O-CH-CH3 CH3 and isopropyl oleat CH3-(CH2)7-CH=CH-(CH2)7-C=O O-CH-CH3 CH3 used in lipstics and lubricants. Isopropanol is also used as an ethanol denaturant, as solvent to concentrate protein, rubbing alcohol, for deicing in drugs and cosmetics and as a general solvent for synthetic resins, shellac, gums, oils and stains.

Acetone is produced by catalytic dehydrogenation or direct oxidation of isopropanol. The catalytic dehydrogenation of isopropanol to acetone over Cu catalyst or brass and zinc oxide ZnO.

CH3-CHOH-CH3 → CH3-C=O CH3 + H2

Direct oxidation with oxygen yields hydrogen peroxide with acetone as a co-product.

CH3-CHOH-CH3 + O2 → H2O2 + CH3-C=O CH3

Oxidation dehydration over Ag or Cu catalyst utilize air as the oxidant,

2 CH3-CHOH-CH3 + O2 → 2 CH3-C=O CH3 + 2 H2O

Acetone is a co-product in the reaction between isopropanol and acrolein CH2=CH-C=O H for production of allyl alcohol CH2=CH-CH2OH over MgO + ZnO catalyst.

CH3-CHOH-CH3 + CH2=CH-C=O H → CH3-C=O CH3 + CH2=CH-CH2OH

Acetone is also produce as a co-product in the production of phenol from cumene, and the by-product of the oxidation of propane and butane. Acetone is now produced directly from propylene using Wacker catalyst system (PdCl2/CuCl2)

2 CH3-CH=CH + O2 → 2 CH3-C=O CH3

Acetone is primarily used as a solvent but it has many synthesis applications, likes synthesis of methyl isobutylketone to produce methyl methacrylate CH2=C-CH3 C=O-OCH3, diacetone alcohol CH3 HO-C-CH3 CH2-C=O-CH3, mesityl oxide CH3 CH3-C=CH-C=O-CH3, phoron CH3 CH3-C=CH-C=O-CH=C-CH3 CH3, ketene CH2=C=O and bisphenol-A HO-[Benzene] CH3-C-CH3 [Benzene]-OH.

Acetone is used in production of dicalcium phosphste CaHPO4 with sulfur dioxide.

CH3-C=O CH3 + SO2 + 2 H2O → CH3 CH3-C-OH SO3- + H3O+

6 CH3 CH3-C-OH SO3H + Ca10(PO4)6F2 + 3 H2O →

6 CaHPO4 + CaF2 + 3 Ca[CH3 CH3-C-OH SO3-]2.H2O

Di-calcium phosphste is an effective fertilizer.

9.4. ACROLEIN CH2=CH-C=O H

Production.

Acrolein is produced by the exothermic catalytic oxidation of propylene with either air or oxygen.

2 CH3-CH=CH + O2 → CH2=CH-C=O H + H2O

Shell and Sohio process are used with the fundamental differences being the source of oxygen and the catalyst. For Shell process the catalyst is CuO, while the Sohio process uses BiO3/MoO3 fixed bed catalyst and air is used as the source of oxygen. The by products are acetaldehyde CH3-C=O H, and acrylic acid CH2=CH-C=O OH. Acrylic acid is made the main product by the addition of a second catalytic reactor that oxidizes the acrolein exothermically to the acid.

2 CH2=CH-C=O H + O2 → 2 CH2=CH-C=O OH

Acrylic acid may be produced by oxidative carbonylation of ethylene with carbon monoxide and oxygen with a Cd2+/Cu2+ catalyst system, while the original method was the carbonylation of acetylene with nickel carbonyl Ni(CO)4 in HCl.

4 HC=CH + Ni(CO)4 + 2 HCl + 4 H2O → 4 CH2=CH-C=O H + NiCl2 + H2

Acrylic acid is stripped to acrylic ester by addition of an esterification reactor at the end of the propylene → acrolein → acrylic acid oxidation system, in liquid phase over an ion exchange resin catalyst.

CH2=CH-C=O H + ROH → CH2=CH-C=O OR + H2O

Uses.

Acrolein’s primary use is in the production of acrylic acid which is used to produce acrylic esters, acrylates. These esters can be produced also from formaldehyde and esters CH2=C=O by way of β-propiolactone CH2-CH2O-C=O. The ketene is produced by the high temperature pyrolysis of acetic acid or acetone.

CH2=C=O + H-C=O H → CH2-CH2O-C=O

CH2-CH2O-C=O + ROH acid→ CH2=CH-C=O OR + H2O

The acrylates, especially ethyl acrylate, CH2=CH-C=O OCH2-CH3 are used in latex coatings, textile finishes, thermosetting finishes, leather finishes and many other general polymer and copolymer uses. Another uses of acrolein is to produced glycerol.

9.5. BUTYRALDEHYDES

Production.

n butyraldehyde CH3-CH2-CH2-C=O H and isobutyraldehyde CH3 CH3-CH-C=O H are produced by the catalytic hydroformylation of propylene with carbon monoxide and hydrogen, the Oxo-reaction, over the old cobalt compounds or the new rhodium compounds catalyst.

2 CH3-CH2=CH2 + 2 CO + 2 H2 → CH3-CH2-CH2-C=O H + CH3 CH3-CH-C=O H

Three advantages of rhodium catalyst are lower reaction temperature, lower pressure and better n- to iso- ratio.

Uses.

The major utiliztion of n-butyraldehyde is to produce n-butanol CH3-CH2-CH2-CH2OH.

This hydrogenation can be integrated into the hydroformylation production line and the reaction is over a variety of catalyst. n-butanol is also produced by the fermentation and from acetaldehyde through aldol CH3-CHOH-CH2-C=O H to crotonaldehyde CH3-CH=CH-C=O H which is hydrogenated to n-butanol.

n-butanol is used as a solvent and estractant and to produce solvents, such as butyl-acetate CH3- C=O OCH2-CH2-CH2-CH3 and other butyl esters n-butyl acrylate CH2=CH-C=O OCH2-CH2-CH2-CH3, is usede in production of plastics. It adds tackiness, softness, plasticity, elongation and low water absorption. n-butyraldehyde is also used to produce 2-ethylhexanol 2-EH, CH3-(CH2)3-CH-C2H5 CH2OH through an aldol condensation, dehydration and hydrogenation.

2 CH3-CH2-CH2-C=O H → CH3-(CH2)2-CH-OH CH-C2H5-C=O H

CH3-(CH2)2-CH-OH CH-C2H5-C=O H → CH3-(CH2)2-CH=C-C2H5-C=O H + H2O

CH3-(CH2)2-CH=C-C2H5-C=O H + 2 H2 → CH3-(CH2)2-CH2-CH-C2H5- CH2OH

The temperatures are 80 – 130 °C for aldolization step and 100 – 150 °C for the hydrogenation.

2-ethylhexanol is used for the production of di-2-ethylhexylphtalate, a plasticizer for vinyl resins. Other uses include the production of its succinate and acrylates, production of antioxidants, antifoams for water solutions and as a special solvent.

n-butyric acid CH3-CH2-CH2-C=O OH is obtained by the liquid phase oxidation of n-butyraldehyde

2 CH3-CH2-CH2-C=O H + H2O → 2 CH3-CH2-CH2-C=O OH

Its major use is in the production of cellulose acetobutyrate. Other esters of n-butyric acid are used as solvents. Isobutyraldehyde is hydrogenated to iso-butanol, iso-butyl alcohol CH3CH3-CH-CH2OH by conventional hydrogenation process, and to minimize ether formation wter is added.

CH3CH3-CH-C=O H + H2 → CH3CH3-CH-CH2OH

Isobutanol is used as a solvent, an additives in lubricating oils and for the production of amide resins. Isobutanol’s main solvent use in the form of its acetate ester, a lacquer solvent. Isobutyraldehyde is oxidized to isobutyric-acid CH3CH3-CH-C=O OH, which is used to produce esters such as isobutyl isobutyrate CH3CH3-CH-C=O OCH2 CH3-CH-CH3.

Another uses is catalytic oxidation of isobutyraldehyde to acetone and isopropanol, usually over transition metal halides such as CoBr2 and NiBr2.

2 CH3CH3-CH-C=O H + 2 ½ O2 → CH3-C=O CH3 + CH3-CHOH-CH3 + H2O + 2 CO2

Neopentyl glycol HOCH2 CH3-C-CH2OH CH3 is produced by the aldol condensation of isobutyraldehyde with formaldehyde, followed by hydrogenation.

CH3CH3-CH-C=O H + H-C=O H → HOCH2 CH3-C-CH3 C=O H

HOCH2 CH3-C-CH3 C=O H + H2 → HOCH2 CH3-C-CH2OH CH3

Neopentyl glycol is used mainly in the production of saturated and unsaturated polyethers, alkyl and polyurethane resinss, as well as plasticizers and synthetic lubricants, it is stable because of primary alcohol structure.

9.6. ALLYL CHLORIDE CH2=CH-CH2Cl

Production.

Allyl chloride is produced by the high temperature chlorination of propylene.

CH2=CH-CH3 + Cl2 → CH2=CH-CH2Cl + HCl

The major by-products are iso and trans 1,3-dichloropropene CHCl=CH-CH2Cl and 1,2 dichloropropane CH2Cl-CHCl-CH3.

Uses.

Allyl chloride is used in production of glycerol. 1,3 dichloropropenes are used as a pesticides, Telone II. Both cause various problems in humans : irritability, breathing difficulties and personality changes.

9.7. ISOPROPYL ACRYLATE CH2=CH O=C-OCH-CH3 CH3

Production.

Isopropyl acrylate can be produced directly from propylene by reaction with acrylic acid over amberlyst 15 + H+ catalyst.

CH2=CH-CH3 + CH2=CH-C=O OH → CH2=CH O=C-OCH-CH3 CH3

Amberlyst 15 is a macroporous sulfonated polystyrene resin

Uses.

Isopropyl acrylate maybe used as a plasticizing copolymer.

9.8. ISOPROPYL ACETATE IPAC CH3 O=C-OCH-CH3 CH3

Production.

Isopropyl acetate can be produced by a direct catalytic vapor phase reaction between dilute refinery grade propylene and technical grade acetic acid on fixed bed catalyst

CH2=CH-CH3 + CH3-C=O OH → CH3 O=C-OCH-CH3 CH3

Uses.

IPAC is used as a solvent for coatings and painting inks, it is generally interchange with methyl ethyl ketone and ethyl acetate.

9.9. ALLYL ACETATE CH3 O=C-OCH2-CH=CH2

Production.

Allyl acetate is produced by the vapor phase reaction between propylene and acetic acid in the presence of oxygen over Pd/KOAc (on alumina) catalyst.

CH2=CH-CH3 + CH3 -C=O OH O2→ CH3 O=C-OCH2-CH=CH2

Uses.

Allyl acetate is hydroformulated to 4-acetoxybutyraldehyde CH3 O=C-OCH2-CH2-CH2-C=O H, which is hydrogenated to 1,4 butanediol 1,4-BDO CH2OH-CH2-CH2-CH2OH.

1,4-BDO can be produced by propylene-based process involving acrolein or produced from butadiene and from maleic anhydride. 1,4 BDO is use to produce tetrahydrofuran, acetylene chemicals, polyurethanes and PBT (polybutylene terephthalate).

9.10. DISPROPORTIONATION

Olefin disproportionation is a catalytic process by which an olefin is converted into shorter and longer-chain olefins, over Al2O3 supported Mo/Co transition metal compound heterogenous catalyst or alkyl halida homogenous catalyst + AlCl2 cocatalyst.

2 CH2=CH-CH3 ↔ CH2=CH2 + CH3-CH=CH-CH3

9.11. CUMENE Iso propyl benzene C6H5-CH-CH3 CH3

The production of cumene from benzene to propylene alkylation is over H3PO4 on kieselguhr or pumice catalyst

C6H6 + CH3-CH=CH2 H3PO4→ C6H5-CH-CH3 CH3

9.12. THE BUTYLENES

Butylenes and butadiene (C4’s) are byproducts of refinery process and of the production of ethylene. Butylenes is used for chemical synthesis, and less for polymer formation than butadienes. n-butenes are unbranched,straight chain, carbon structure C-C-C-C, while isobutylene has a branched-chain structure C-C-C C, so make an appreciable difference in the type of reaction, rate of reaction and general chemical utilization. Butylene mainly used for alkylation.

9.12.1. N-butenes

There are 3 n-butenes, 1-butene CH3-CH2-CH=CH2, cis 2-butene CH3 H-C=C-H CH3 and trans 2-butene CH3 H-C=C-CH3 H. Both the reaction between 1-butene and 2-butene give the same products, such as hydration to produce secondary butanol. To separate 1-butene (bp -6.3 °C), 2-butene (bps 0.9 and 3.7 °C) and iso butylene (bp -6.6 °C), is by isomerizing with hydrogen the 1-butene to 2-butene, followed b y fractionation. The isomerization process yields two streams, 2-butene and the other of isobutylene. The standard method for separation of C4 olefin is to remove the butadiene by extraction and isobutylene by absorbtion in cold sulfuric acid. The isobutylene polymerizes to di- and tri-isobutylene which go to the gasoline pool. 1-butene is used to produce polybutylene and butylene oxide CH3-CH2-CH-O-CH2, while 1-butene or 2-butene is used to produce secondary butanol CH3-CHOH-CH2-CH3, methyl ethyl ketone CH3-C=O CH2-CH3, acetic acid CH3-C=O OH, maleic anhydride O=C-CH-O-CH-C=O, butadiene CH2=CH-CH=CH2.

9.12.2. Sec-butanol, 2-butanol, sec-butyl alcohol, SBA CH3-CHOH-CH2-CH3

Production.

Sec-butanol is produced by sulfuric acid esterification of the n-butenes followed by hydrolysis of the resulting mixture of sec-butyl hydrogen sulfate and di sec-butyl sulfate.

Sulfation : 3 CH3-CH2-CH=CH2 + H2SO4 →

CH3-CH2-CH-CH3 OSO3H + CH3-CH2-CH-CH3 OSO2O-CH-CH3 CH2-CH3

Hydrolysis : CH3-CH2-CH-CH3 OSO3H + CH3-CH2-CH-CH3 OSO2O-CH-CH3 CH2-CH3 + 3 H2O →

3 CH3-CHOH-CH2-CH3 + H2SO4

The reaction condition are similar with the production of isopropanol from propylene by sulfuric acid esterification process.

Uses.

SBA is mainly converted to methyl ethyl keton MEK CH3-C=O CH2-CH3 by dehydrogenation.

9.12.3. Methyl Ethyl Ketone, 2 butanone CH3-C=O CH2-CH3

Production.

MEK is produced directly from n-butenes by liquid phase Wascher-type process over PdCl2/CuCl2 catalyst, similar to the process used to produce acetaldehyde from ethylene.

2 CH3-CH2-CH=CH2 + O2 → 2 CH3-C=O CH2-CH3

MEK is also produced by the dehydrogenation of sec-butyl alcohol over ZnO or brass (Cu-Zn) catalyst, which is similar to produce acetone from propylene.

CH3-CHOH-CH2-CH3 → 2 CH3-C=O CH2-CH3 + H2

MEK is also produced by liquid phase process uses Raney nickel or copper chromite as the dehydrogenation catalyst, and also produced as a by product of the oxidation of butane.

Uses.

MEK is used as a solvent, lubricating oil refining and selectively dissolves the oil from wax. MEK is also used as reaction solvent in one of the terephthalic acid processes. MEK is also used in the synthesis of various compounds, includingmethyl ethyl ketoxime CH3-CH2 CH3-C=N-OH an anti skimming agent, methyl ethyl ketone peroxide CH3-CH2 CH3-C-OH O-O CH3-C-OH -CH2-CH3, a polymerization catalyst, especially for acrylic and polyester polymers, and methyl pentynol CH3-CH2 CH3-C-OH C=CH a corrosion inhibitor.

9.12.4. Acetic Acid, ethanoic acid CH3-C=O OH

Production.

Acetic acid is produced by several commercial processes, including the oxidation of acetaldehyde, the carbonylation of methanol over rhodium promoted by iodine catalyst CH3OH + CO → CH3-C=O OH and the oxidation of butane and other paraffin hydrocarbons. Acetic acid is also produced by direct catalytic oxidation of n-butene over vanadates of Ti, Al, Sn, Sb and Zn catalysts.

CH3-CH=CH-CH3 + 2 O2 → 2 CH3-C=O OH

There are another two step process for the oxidation of n-butenes to acetic acid. The n-butenes are esterified with acetic acid to sec-butyl acetate CH3-C=O OCH-CH3 CH2-CH3 over acid exchange resin catalyst, which is then oxidized to three moles of acetic acid.

Esterification CH3-CH2-CH=CH2 + CH3-C=O OH → CH3-C=O OCH-CH3 CH2-CH3

Oxidation CH3-C=O OCH-CH3 CH2-CH3 + 2 O2 → 3 CH3-C=O OH

CH3-CH2-CH=CH2 + 2 O2 → 2 CH3-C=O OH

Uses.

This synthetic acid is utilized primarily in the form of esters, like to produce vinyl acetate CH3-C=O OCH=CH2 with ethylene, ethyl acetate CH3-C=O OCH2-CH3, butyl acetate CH3-C=O OCH2-CH2-CH2-CH3, and amyl acetate CH3-C=O OCH2-(CH2)3-CH3. Acetic acid is also used to produce acetic anhydride CH3-C=O O-C=O CH3.

Acetic anhydride CH3-C=O O-C=O CH3.

Acetic anhydride may be produced from acetaldehyde, acetone or acetic acid. With both acetone and acetic acid, the initial product is ketene CH2=C=O, which is highly reactive and reacts readily with acetic acid to form acetic anhydride, and the reaction take place over 0.2 – 0.3 TEP (CH3-CH2)3.PO4 catalyst.

CH3-C=O OH → CH2=C=O + H2O

CH2=C=O + CH3-C=O OH → CH3-C=O O-C=O CH3

2 CH3-C=O OH → CH3-C=O O-C=O CH3 + H2O

Acetic anhydride is used to make acetic acid esters for cellulose acetate.

CH3-C=O O-C=O CH3 + ROH → CH3-C=O OR + CH3-C=O OH

9.12.5. Maleic anhydride O=C-CH-O-CH-C=O

Production.

Maleic anhydride is produced by oxidation of butane.

2 CH3-CH2-CH2-CH3 + 7 O2 → 2 O=C-CH-O-CH-C=O + 8 H2O

It is also produced by oxidation of benzene over V2O5/MoO3 catalyst.

2 C6H6 + 9 O2 → O=C-CH-O-CH-C=O + 4 H2O + 4 CO2

Or oxidation of n-butene and 1-butene over Mo-V-P oxides on silica gel catalyst

CH3-CH=CH-CH3 + 3 O2 → O=C-CH-O-CH-C=O + 3 H2O

Uses.

Maleic anhydride is used to modify plastic properties because it readily copolymerizes with various other substances but does not polymers with it self. It is used to modify alkyd resins and drying oils such as linseed, soy and sunflower oils. It is also make malathion (CH3O)2 S=PS-CH-C=O--OCH2-CH3 CH2-C=O OCH2-CH3 an important insecticide and maleic hydrazide

O=C-CH=CH-C≡N =O NH2, a plant growth regulator.

9.12.6. Butylene oxide CH3-CH2-CH-O-CH2

Production.

Butylene oxide is produced from 1-butene by chlorohydrination with hypochlorous acid followed by epoxidation.

Chlorohydrination CH3-CH2-CH=CH2 + HOCl → CH3-CH2-CHOH-CH2Cl

Epoxidation 2 CH3-CH2-CHOH-CH2Cl + Ca(OH)2 → 2 CH3-CH2-CH-O-CH2 + CaCl2 + 2 H2O

It is similar to chlorohydrination process for the production of propylene oxide from propylene.

Uses.

Butylene oxide is hydrolyzed to butylene glycol CH3-CH2-CHOH-CH2OH which is used in the production polymeric plasticizers.

CH3-CH2-CH-O-CH2 + H2O H+→ CH3-CH2-CHOH-CH2OH

1, 2 butylene oxide is a stabilizer for 1, 1, 1 –trichloroethane (methyl chloroform) CH3-CCl3, and other chlorinated solvents. Other uses include applications such as pharmaceuticals, surfactants and agrochemicals.

9.13. ISOBUTYLENE, Isobutene CH3 CH3-C=CH2

Isobutylene is not used extensively as a chemical precursor because many of its derivatives have the reactive tertiary structure CH3 CH3-C-CH3 , which has a tendency to revert to isobutylene. Tert- butyl alcohol CH3 CH3-C-OH CH3 and its derivatives methyl tertiary butyl ether CH3 CH3-C-OCH3 CH3 MTBE and isobutylene oxide CH3 CH3-C-O-CH2 are examples, but alkylation reactions such as the alkylation of p-cresol to 2, 6 – di –tert-butyl- p- cresol CH3 CH3-C-CH3 OH-C6H2-CH3 CH3-C-CH3 CH3 produce stable compounds. Reactions which preserve the carbon-carbon double bond also produce stable compounds. The oxidation of isobutylene to methacrylic acid CH2=C-CH3 C=O OH is an example. Isobutylene dimerizes readily with it self and with other olefins to form higher molecular weight olefins such as diisobutylene CH3 CH3-C-CH3 CH2 CH3-C=CH2 and ‘heptene C7H14’. It also readily with alkylates, benzene and its derivatives. Chemical utilization of isobutylene mainly as butyl rubber and polybutylenes.

9.13.1. Tert-butyl alcohol TBA CH3 CH3-C-OH CH3

Production.

TBA is produced by the sulfation-hydrolysis process, used to produce sec-butanol, from the n-butenes with 50 – 65 % H2SO4.

CH3 CH3-C=CH2 + H2O H+→ CH3 CH3-C-OH CH3

TBA is also produced as a co-product in the tert-butyl epoxidation of propylene to propylene oxide. TBA is usually dehydrated to obtain pure isobutylene.

Uses

TBA is used as a solvent and also as a raw material in the production of p-tert butyl phenol CH3 CH3-C-C6H4-OH CH3 which is an intermediate for oil soluble phenol formaldehyde resins. YBA has been proposed as feed stock for methyl methacrylate MMA. TBA is oxidized to methacrolein CH3 CH2=C-C=O H, then it is converted to methacrylic acid CH3 CH2=C-C=O OH which is esterified with methanol to yield methyl methacrylate MMA CH3 CH2=C-C=O OCH3. TBA has a research octane number RON 108 and proposed as a gasoline additive.

9.13.2. Methyl tert-butyl ether CH3 CH3-C-OCH3 CH3.

Production.

MTBE is produced by liquid phase reaction between isobutylene and methanol over sulfonated polystyrene resin catalyst in mild temperature.

CH3 CH3-C=CH2 + CH3OH → CH3 CH3-C-OCH3 CH3.

Actually the feed is a mixed steam cracker product with the butadiene remove. The reaction conditiopn are mild to permit the n-butenes to pass through without ether formation.

Uses.

MTBE is an excellent octane booster. Tert-amylmethyl ether TAME has been proposed as comparable to MTBF. The octane number for MTBE are RON-118 and MON-101, while for TAME are RON-112 and MON-99. TAME is produced from isoamylenes (2 methyl 1 butene and 2 methyl 2 butene).

9.13.3. Isobutylene oxide CH3 CH3-C-O-CH2

Production.

Isobutylene oxide is produced by chlorohydrination of isobutylene followed by epoxidation of the chlorohydrin by reaction with a base. The process is similar to produce butylene oxide and propylene oxide.

The direct non catalytic liquid phase oxidation of isobutylene to isobutylene oxide is :

2 CH3 CH3-C=CH2 + O2 → CH3 CH3-C-O-CH2

With the by-product is isobutylene glycol, isobutylene glycol ester, acetone, tert-butyl alcohol, etc.

Direct catalytic liquid phase oxidation process in an acetic acid-water-tetrahydrofuran solution also has been proposed over Tl(O O=C-CH3)3 catalyst, where at slightly higher temperature the epoxide is hydrolyzed to the glycol.

Uses.

Isobutylene oxide is hydrolyzed to isobutylene glycol in an acid solution.

CH3 CH3-C-O-CH2 + H2O → CH3 CH3-COH-CH2OH

The glycol can be oxidized to α-hydroxyisobutyric acid over 5% Pt/C catalyst at pH 2-7.

CH3 CH3-COH-CH2OH + O2 → CH3 CH3-COH-C=O OH + H2O

The hydroxy acid is readily dehydrated to give methacrylic acid CH3 CH2=C-C=O OH

9.13.4. Isobutylene glycol CH3 CH3-COH-CH2OH

Production.

Isobutylene glycol is synthesized by direct catalytic liquid phase oxidation of isobutylene.

2 CH3 CH3-C=CH2 + O2 + H2O → 2 CH3 CH3-COH-CH2OH

The isobutylene is oxidized by Tl3+ ions to isobutylene glycol. The Tl3+ ions are regenerated from Tl+ ions by a CuCl2/O2 couple (Wacker type process).

TlCl + 2 CuCl2 → TlCl3 + 2 CuCl

4 CuCl + 4 HCl + O2 → 4 CuCl2 + 2 H2O

Coupled with the glycol oxidation to α-hydroxyisobutyric acid a viable route from isobutylene to methacrylic acid is present.

9.13.5. Methacrolein-methacrylic acid MAA CH3 CH2=C-C=O H - CH3 CH2=C-C=O OH

The methyl ester of MAA is a useful vinyl monomer produced by acetone cyanohydrin process.

This process has toxicity problems and a large ammonium sulfate waste stream.

CH3-C=O CH3 + HCN → CH3 CH3-COH-CN

CH3 CH3-COH-CN + H2SO4 → CH3 CH2=C-C=O NH2.H2SO4

CH3 CH2=C-C=O NH2.H2SO4 + CH3OH → CH3 CH2=C-C=O OCH3 + NH4HSO4

Production.

Isobutylene is process directly to methacrylic acid or indirectly to methacrolein as an intermediate. Ammoxidation of isobutylene to methacrylonitrile CH3 CH2=C-CN, in a process similar to produce acrylonitrile from propylene. When nitrogen dioxide NO2 is used as the oxidant, both methacrolein and methacrylonitrile are produced in low yields.

Another viable process is the air oxidation of isobutylene,

CH3 CH2=C-CH3 + O2 → CH3 CH2=C-C=O H + H2O

2 CH3 CH2=C-C=O H + O2 → 2 CH3 CH2=C-C=O OH

This is a two step process because of the different oxidation characteristic of isobutylene and methacrolein. Isobutylene oxidation to methacrolein is over complex molybdenum oxide promoted with overall selected oxides supported on a grain carrier catalyst, while methacrolein oxidation to methacrylic acid is over a supported molybdenum compound with some specific promoter.

Uses.

Methacrylic acid is esterified with methanol to methyl methacrylate MMA CH3 CH2=C-C=O OCH3, to produce polymer cast sheet, molding and extrusion powders and coatings. It polymerizes readily to a homopolymer or various copolymers.

9.14. HEPTENES C7H14.

Production.

Isobutylene and propylene can be dimerized in the presence of phosphoric acid or aluminum chloride to a mixture of heptenes.

Uses.

Heptenes mixtured is hydroformulated, Oxo reaction, then hydrogenated to isooctanol, used to make phthalate plasticizers, similar to those of 2-ethylhexanol.

9.15. DIISOBUTYLENE CH3 CH3-C-CH3 C-CH2 CH3-C=CH2, CH3 CH3-C-CH3 C-CH=C-CH3 CH3

Production.

Diisobutylene is a by-product of isobutylene extraction with sulfuric acid.

2 CH3 CH2=C-CH3 H+→ CH3 CH3-C-CH3 C-CH2 CH3-C=CH2 + CH3 CH3-C-CH3 C-CH=C-CH3 CH3

Diisobutylene as well as heptenes are produced by Dimersol process. This is a selective liquid phase codimeriztion or dimerization of propylene and or butylene cuts. The process is at low pressure and ambient temperature in the presence of soluble catalyst system.

Uses.

Diisobutylene is used to make octylphenol for the production of nonionic detergents. Nonyl alcohols are produced by the Oxo reaction. The nonyl alcohols are used to make plasticizers, etc. Heptenes and diisobutylenes are for octane improvement of gasoline.

9.15.1. Neo-pentanoic acid CH3 CH3-C-CH3 C=O OH

Production.

Neo pentanoic acid is produced by the high pressure addition of carbon monoxide to isobutylene in the presence of an acid catalyst to produce a CO-catalyst olefin complex-an acyl carbonium ion, followed by low pressure hydrolysis.

CH3 CH2=C-CH3 + H+ + CO → [CH3 CH3-C-CH3 CO]+

[CH3 CH3-C-CH3 CO]+ + H2O → CH3 CH3-C-CH3 C=O OH + H+

Uses.

Neo pentanoic acid has very stable ‘neo’ structure. It is used where a very stable acid and esters are required.

9.16. BUTADIENE CH2=CH-CH=CH2

The butadiene production is utilized in direct polymer formation. The polymer distribution is Styrene-Butadiene-rubber (50%), polymer (20%), and other rubbers (10%). The future of butadiene lies with synthetic rubber.

9.16.1. Hexamethylene diamine HMDA H2N-(CH2)6-NH2

Production.

HMDA was initially produced from butadiene by the addition of chlorine at 150 °C followed by cyanation and hydrogenation.

2 CH2=CH-CH=CH2 + 2 Cl2 → CH2Cl-CH=CH-CH2Cl + CH2Cl-CHCl-CH=CH2

The 1, 4 addition product predominates but the 1, 2 addition product gives the same 1,4 dinitrile with NaCN (or HCN) over Cu2Cl2 catalyst.

CH2Cl-CH=CH-CH2Cl + 2 NaCN → NC-CH2-CH=CH-CH2-CN

The 1, 4 dicyano 2 butene is hydrogenated to adiponitrile NC-(CH2)4-CN over Pd on C catalyst.

NC-CH2-CH=CH-CH2-CN + H2 → NC-CH2-CH2-CH2-CH2-CN

Adiponitrile can be produced by addition of hydrogen cyanide HCN to butadiene, in two step process,

2 CH2=CH-CH=CH2 + 2 HCN → CH3-CH=CH-CH2-CN + CH2=CH-CH2-CH2-CN

This first step is over CuMgCrO (+HCl, N2) catalyst, while in the second step HCN reacts with the mononitriles to form to 1, 4 dinitrile over Ni (tolyphosphite)3 + SnCl2 catalyst.

CH3-CH=CH-CH2-CN + CH2=CH-CH2-CH2-CN + 2 HCN → 2 NC-CH2-CH2-CH2-CH2-CN

Adiponitrile is also produced by electrodimeriztion of acrylonitrile.

Anode H2O – 2e- H+ → 2 CH2=CH-CN Cathode

↓ ↓ +2H+ + 2e-

½ O2 + 2 H+ H+ → NC-(CH2)4-CN

Anolyte Catholyte

Adiponitrile is hydrogenated in the liquid phase to hexamethylene diamine HMDA over Co Catalyst.

NC-CH2-CH2-CH2-CH2-CN + 4 H2 → H2N-CH2-CH2-CH2-CH2-CH2-CH2-NH2

HMDA is also produced by the reaction between adipic acid HO O=C-(CH2)4-C=O OH and ammonia followed by dehydration.

Uses.

HMDA plus adipic acid polymerize to form nylon-66.

9.16.2. Adipic Acid AA HO O=C-(CH2)4-C=O OH

Production.

It has been proposed to produce adipic acid AA by liquid phase catalytic carbonylation of butadiene over RhCl2 + CH3I promoter catalyst.

CH2=CH-CH=CH2 + 2 CO + 2 H2O → HO O=C-(CH2)4-C=O OH

Uses.

Adipic acid is used to produce nylon 66. AA also can be used to produced sebacic acid SA,

HO O=C-(CH2)8-C=O OH by a three step electroxidation process.

a. esterification with cation exchange resin of sulfonic acid form catalyst :

HO O=C-(CH2)4-C=O OH + CH3OH → CH3-O O=C-(CH2)4-C=O OH

b. electrolysis

2 CH3-O O=C-(CH2)4-C=O O- -e→ CH3-O O=C-(CH2)8-C=O O-CH3 + 2 CO2

2 H+ + e → H2

c. hydrolysis

CH3-O O=C-(CH2)8-C=O O-CH3 + 2 H2O → HO O=C-(CH2)8-C=O OH + 2 CH3OH

9.16.3. 1,4-butanediol HOCH2-(CH2)2-CH2OH

Production.

The production of 1,4 butanediol is from propylene by way of allyl acetate CH3 O=C-OCH2-CH=CH2,

CH3 O=C-OCH2-CH=CH2 → CH3 O=C-OCH2-CH2-CH2-C=O H → HOCH2-(CH2)2-CH2OH

Butadiene also can serve as a starting material for production 1,4 BDO by a three step process. The first step is the liquid phase acetoxylation of butadiene to 1,4 1,4 diacetoxy- 2 butene over Pd-Te on carbon catalyst,

2 CH2=CH-CH=CH2 + 4 CH3-C=O OH →

CH3 O=C-OCH2-CH=CH-CH2O-C=O CH3 + CH3 O=C-O-CH-CH=CH2 CH2O-C=O CH3

The second step consist of hydrogenation of the 1,4 diacetoxy- 2 butene to 1,4 diacetoxy butane over Ni-Zn on diatomaceous earth catlyst,

CH3 O=C-OCH2-CH=CH-CH2O-C=O CH3 + H2 → CH3 O=C-OCH2-CH2-CH2-CH2O-C=O CH3

The third step is conventional hydrolysis to 1, 4 BDO

CH3 O=C-OCH2-CH2-CH2-CH2O-C=O CH3 + 2 H2O → HOCH2-(CH2)2-CH2OH + 2 CH3-C=O OH

The overall reaction is

CH2=CH-CH=CH2 + H2O → HOCH2-(CH2)2-CH2OH

The production of 1, 4 BDO is also from maleic anhydride.

Uses.

Two main uses of 1, 4 BDO are the production of tetrahydrofuran CH2-CH=O=CH-CH2 and acetylene chemicals. It also goes into the polyurethanes, synthetic rubber, thermoplastic polyester and palsticizer industries.

9.16.4. Sulfolane, tetramethylene sulfone CH2-CH2-SO2-CH2-CH2

Production.

Sulfolane is produced by hydrogenation of sulfolene CH2-CH=SO2=CH-CH2, which is produced from butadiene and sulfur dioxide, CH2=CH-CH=CH2 + SO2 ↔ CH2-CH=SO2=CH-CH2.

This is a n equilibrium reaction with the highest sulfolene concentration at 75 oC. The crystalline sulfolene will decompose to butadiene and sulfur dioxide at 125 oC. Sulfur dioxide will react exclusivelly with butadiene in the presence of butenes. This is a simple method for obtains pure butadiene from a mixture of butadiene and n-butenes. The sulfolene is hydrogenated to the sulfolane by conventional process.

CH2-CH=SO2=CH-CH2 + H2 → CH2-CH2-SO2-CH2-CH2

Uses.

A mixture of sulfolane and diisopropanolamines is used for acid gas removal, especially carbon dioxide, the Sulfinol process. Sulfolane is also used for the extraction of aromatics from petroleum or coke-oven sources. High purity aromatics are produced. High octane number aromatics concentrates for gasoline blending also can be produced by this process.

9.16.5. Chloropene, 2 chloro - 1, 3 butadiene CH2=C-Cl CH=CH2

Chloropene is produced from butadiene by high temperature chlorination followed by isomerization to 3, 4 dichloro – 1 butene CH2=CH-CHCl-CH2Cl, which is dehydrochlorinated to chloropene.

CH2=CH-CHCl-CH2Cl → CH2=C-Cl CH=CH2 + HCl

Conventional synthesis of chloropene is the addition of hydrogen chloride to vinyl acetylene,

CH2=CH-C=CH + HCl → CH2=C-Cl CH=CH2

Uses.

Chloropene is polymerized to give a rubber with excellent resistance to oil, solvents and ozone-cracking.

9.16.6. Dimers

Butadiene can be dimerized by TiCl3/AlCl3 to 1, 3 - cyclooctadienes, CH2-CH=CH-CH=CH-CH2-CH2-CH2and 1, 5 – cyclooctadienes, CH2-CH=CH-CH2-CH2-CH=CH-CH2

The cyclooctadienes are converted into nylon-8 by way of cyclooctanone oxime or by way of suberic acid, HOCH2-(CH2)6-CH2OH. This acid is also used to produce synthetic lubricants. The major use of the 1, 5 – isomer is a the third comonomer in ethylene-propylene rubber.

Butadiene trimer 1, 5, 9 cyclododecatriene is used as a precursor of nylon-12.

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