GATE Chemical Engineering

um fractions. Chemical plants produce olefins by steam cracking of natural gas liquids like ethane and propane. Olefins and aromatics are the building-blocks for a wide range of materials such as solvents, detergents, and adhesives. Olefins are the basis for polymers and oligomers used in plastics, resins, fibers, elastomers, lubricants, and gels. Global ethylene and propylene production are about 115 million tonnes and 70 million tonnes per annum, respectively. Aromatics production is approximately 70 million tonnes. The largest petrochemical industries are located in the USA and Western Europe; however, major growth in new production capacity is in the Middle East and Asia. There is substantial inter-regional petrochemical trade. Primary petrochemicals are divided into three groups depending on their chemical structure:

Olefins includes ethylene, propylene, and butadiene. Ethylene and propylene are important sources of industrial chemicals and plastics products. Butadiene is used in making synthetic rubber. Aromatics includes benzene, toluene, and xylenes. Benzene is a raw material for dyes and synthetic detergents, and benzene and toluene for isocyanates MDI and TDI used in making polyurethanes. Manufacturers use xylenes to produce plastics and synthetic fibers. Synthesis gas is a mixture of carbon monoxide and hydrogen used to make ammonia and methanol. Ammonia is used to make the fertilizer urea and methanol is used as a solvent and chemical intermediate. The prefix "petro-" is an arbitrary abbreviation of the word "petroleum"; since "petro-" is Ancient Greek for "rock" and "oleum" means "oil". Therefore, the etymologically correct term would be "oleochemicals". However, the term oleochemical is used to describe chemicals derived from plant and animal fats. Sources[edit]


Petrochemical feedstock sources
The adjacent diagram schematically depicts the major hydrocarbon sources used in producing petrochemicals are:

Methane, ethane, propane and butanes: Obtained primarily from natural gas processing plants. Naphtha obtained from petroleum refineries. Benzene, toluene and xylenes, as a whole referred to as BTX and primarily obtained from petroleum refineries by extraction from the reformate produced in catalytic reformers. Gas oil obtained from petroleum refineries. Methane and BTX are used directly as feedstocks for producing petrochemicals. However, the ethane, propane, butanes, naphtha and gas oil serve as optional feedstocks for steam-assisted thermal cracking plants referred to as steam crackers that produce these intermediate petrochemical feedstocks:

Ethylene
Propylene
Butenes and butadiene
Benzene
In 2007, the amounts of ethylene and propylene produced in steam crackers were about 115 Mt (megatonnes) and 70 Mt, respectively. The output ethylene capacity of large steam crackers ranged up to as much as 1.0 – 1.5 Mt per year. Steam crackers are not to be confused with steam reforming plants used to produce hydrogen and ammonia. Manufacturing locations[edit]

Like commodity chemicals, petrochemicals are made on a very large scale. Petrochemical manufacturing units differ from commodity chemical plants in that they often produce a number of related products. Compare this with specialty chemical and fine chemical manufacture where products are made in discrete batch processes. Petrochemicals are predominantly made in a few manufacturing locations around the world, for example in Louisiana in the USA, in Teesside in the Northeast of England in the United Kingdom, in Rotterdam in the Netherlands and in Jamnagar & Dahej in Gujarat India. Not all of the petrochemical or commodity chemical materials produced by the chemical industry are made in one single location but groups of related materials are often made in adjacent manufacturing plants to induce industrial symbiosis as well as material and utility efficiency and other economies of scale. This is known in chemical engineering terminology as integrated manufacturing. Speciality and fine chemical companies are sometimes found in similar manufacturing locations as petrochemicals but, in most cases, they do not need the same level of large scale infrastructure (e.g., pipelines, storage, ports and power, etc.) and therefore can be found in multi-sector business parks. The large scale petrochemical manufacturing locations have clusters of manufacturing units that share utilities and large scale infrastructure such as power stations, storage tanks, port facilities, road and rail terminals. In the United Kingdom for example, there are 4 main locations for such manufacturing: near the River Mersey in Northwest England, on the Humber on the East coast of Yorkshire, in Grangemouth near the Firth of Forth in Scotland and in Teesside as part of the Northeast of England Process Industry Cluster (NEPIC). To demonstrate the clustering and integration, some 50% of the United Kingdom's petrochemical and commodity chemicals are produced by the NEPIC industry cluster companies in Teesside. List of significant petrochemicals and their derivatives[edit]

The following is a partial list of the major commercial petrochemicals and their derivatives:


Chemicals produced from ethylene
ethylene - the simplest olefin; used as a chemical feedstock and ripening stimulant
polyethylene - polymerized ethylene
ethanol - via ethylene hydration (chemical reaction adding water) of ethylene
ethylene oxide - via ethylene oxidation
ethylene glycol - via ethylene oxide hydration
engine coolant - ethylene glycol, water and inhibitor mixture
polyesters - any of several polymers with ester linkages in the backbone chain
glycol ethers - via glycol condensation
ethoxylates
vinyl acetate
1,2-dichloroethane
trichloroethylene
tetrachloroethylene - also called perchloroethylene; used as a dry cleaning solvent and degreaser
vinyl chloride - monomer for polyvinyl chloride
polyvinyl chloride (PVC) - type of plastic used for piping, tubing, other things

Chemicals produced from propylene
propylene - used as a monomer and a chemical feedstock
isopropyl alcohol - 2-propanol; often used as a solvent or rubbing alcohol
acrylonitrile - useful as a monomer in forming Orlon, ABS
polypropylene - polymerized propylene
propylene oxide
polyether polyol - used in the production of polyurethanes
propylene glycol - used in engine coolant and aircraft deicer fluid
glycol ethers - from condensation of glycols
acrylic acid
acrylic polymers
allyl chloride -
epichlorohydrin - chloro-oxirane; used in epoxy resin formation
epoxy resins - a type of polymerizing glue from bisphenol A, epichlorohydrin, and some amine
C4 hydrocarbons - a mixture consisting of butanes, butylenes and butadienes
isomers of butylene - useful as monomers or co-monomers
isobutylene - feed for making methyl tert-butyl ether (MTBE) or monomer for copolymerization with a low percentage of isoprene to make butyl rubber
1,3-butadiene (or buta-1,3-diene) - a diene often used as a monomer or co-monomer for polymerization to elastomers such as polybutadiene, styrene-butadiene rubber, or a plastic such as acrylonitrile-butadiene-styrene (ABS)
synthetic rubbers - synthetic elastomers made of any one or more of several petrochemical (usually) monomers such as 1,3-butadiene, styrene, isobutylene, isoprene, chloroprene; elastomeric polymers are often made with a high percentage of conjugated diene monomers such as 1,3-butadiene, isoprene, or chloroprene
higher olefins
polyolefins such poly-alpha-olefins, which are used as lubricants
alpha-olefins - used as monomers, co-monomers, and other chemical precursors. For example, a small amount of 1-hexene can be copolymerized with ethylene into a more flexible form of polyethylene. other higher olefins
detergent alcohols

Chemicals produced from benzene
benzene - the simplest aromatic hydrocarbon
ethylbenzene - made from benzene and ethylene
styrene made by dehydrogenation of ethylbenzene; used as a monomer
polystyrenes - polymers with styrene as a monomer
cumene - isopropylbenzene; a feedstock in the cumene process
phenol - hydroxybenzene; often made by the cumene process
acetone - dimethyl ketone; also often made by the cumene process
bisphenol A - a type of "double" phenol used in polymerization in epoxy resins and making a common type of polycarbonate
epoxy resins - a type of polymerizing glue from bisphenol A, epichlorohydrin, and some amine
polycarbonate - a plastic polymer made from bisphenol A and phosgene (carbonyl dichloride)
solvents - liquids used for dissolving materials; examples often made from petrochemicals include ethanol, isopropyl alcohol, acetone, benzene, toluene, xylenes
cyclohexane - a 6-carbon aliphatic cyclic hydrocarbon sometimes used as a non-polar solvent
adipic acid - a 6-carbon dicarboxylic acid, which can be a precursor used as a co-monomer together with a diamine to form an alternating copolymer form of nylon. nylons - types of polyamides, some are alternating copolymers formed from copolymerizing dicarboxylic acid or derivatives with diamines
caprolactam - a 6-carbon cyclic amide
nylons - types of polyamides, some are from polymerizing caprolactam
nitrobenzene - can be made by single nitration of benzene
aniline - aminobenzene
methylene diphenyl diisocyanate (MDI) - used as a co-monomer with diols or polyols to form polyurethanes.