1.1 Why Petrochemical Products Are Important for the Economy
To understand the economic significance of petrochemical products, it is important to first look at some of the history of the petrochemical industry. Aromatics such as benzene, toluene, and the C8 aromatic isomers have long been of interest to chemists and chemical engineers. In the earliest stages of the chemical industry, these aromatics were recovered by distillation from coal tar, which was a byâproduct of steel production. In addition to being used as solvents, these basic aromatics could be fairly easily converted into functional derivatives by chlorination, nitration, and similar chemistries, usually in batch operation. Basic intermediates, such as diâchloro benzene isomers, nitro benzene, and chloroânitro benzene, found their way into agricultural chemicals and pharmaceuticals, among other applications.
In the midâ1800s, styrene (aka styrol) had been found by Erlenmeyer to be capable of producing a dimer, which explained how, when styrene was exposed to air, heat, and sunlight, it would form a hard, rubbery substance. This may have been the first recognition of the potential for aromatics to be useful for polymers. Ethylene followed a similar, but much later pathway with the accidental discovery of polymerization in 1898, followed by industrial polyethylene synthesis in 1933. Ethylene became relatively abundant via steam cracking, and benzene by recovery from naphtha fractions. This led to the use of polyethylene and polystyrene for military purposes during WW II.
Propylene was converted via dimers and trimers into a gasoline component that could be blended with FCC gasoline and naphtha. Cumene, the reaction product of benzene and propylene, was produced in large quantities during WW II as a highâoctane component for aviation gasoline, but it was not until near the end of WW II that the Hoch process for oxidation of cumene to phenol and acetone was discovered. Phenol and acetone each have many end uses as solvents or derivatives in pharmaceuticals, agricultural chemicals, and other applications. But more than 65% of the world's phenol is converted into polymers.
After WW II, companies began to focus on ways to sustain economic growth beyond supplying wartime materials, and they focused on emerging consumer goods. With increased automobile production came the need for large amounts of higher octane gasoline. UOP discovered and commercialized catalytic reforming of naphtha to aromatics using a supported platinum catalyst. This process was called Platforming⢠and it became a mainstay of refining for its capability to produce significant aromatics along with valuable hydrogen. This development, along with the confluence of polymerization knowledge, and the capacity for production of ethylene and propylene, led to the origins of today's petrochemicals industry. Over the years, polymer chemists have created numerous grades of polyethylene, polypropylene, polystyrene, polycarbonate, and polyethylene terephthalate (PET) for use in the apparel, packaging, automotive, electronics, medical, and numerous other industries. Biodegradable detergents also are derived from hydrocarbon feeds, using benzene and the linear highâmolecular weight olefins that are derived from nâparaffins. All of these products make use of the abundance of hydrocarbons being produced from crude oil, LPG, and natural gas liquids.
1.1.1 Polyethylene
Today, polyethylene is the most prominent polymer worldwide, with more than 140 million tons per year being produced. It is extremely durable and is used for production of containers, insulators, coatings, pipe, liners, and films. Industries such as packaging, electronics, power transmission, consumer, and household goods produce components or end products made from polyethylene, with significant job creation in finished goods.
1.1.2 Polypropylene
Polypropylene is a thermoplastic polymer with numerous uses, including textiles, packaging, consumer goods, appliances, electrical and manufacturing industries, and automotive and construction industries. More than 90 million tons per year of polypropylene are produced worldwide. The job creation and added value impact is very high in both developed and emerging regions.
1.1.3 Styrene and Polystyrene
Styrene is used in the production of latex, synthetic rubber, and polystyrene resins. Primary categories of styrene are: films, foams, composites, ABS plastic, SAN plastic, SB rubber, and SB latex. It is used in plastic packaging; building insulation; cups and containers; composite products such as tubs, showers, auto body parts, boats, and wind turbines; medical devices; optical fibers; tires; and backing for carpets. Worldwide demand is mo...
