The petrochemical industry (making chemicals from mineral oil) was started in the USA in the 1920s. Expansion of the Grangemouth oil refinery in 1947 provided an opportunity for the Anglo-Iranian Oil Company (from 1954 BP) to get into chemical manufacture. The Distillers Company (DCL) was already involved in making organic chemicals (based on the chemistry of the element carbon) from industrial alcohol, so a joint company was formed with it. At first called BP Chemicals, the name changed to British Hydrocarbon Chemicals (BHC) in 1956.
Europe's first ethylene cracker plant was opened at Grangemouth in 1951. A light petroleum distillate from the refinery was subjected to heat and steam in tubular furnaces, where it was 'cracked' into the simple reactive chemicals ethylene and propylene, which are the building blocks of the petrochemical industry. 32,000 tons of ethylene could be made per year. Plants to make ethyl alcohol (industrial alcohol) from ethylene, and isopropyl alcohol from the propylene were started up the the same time.
Joint ventures with other companies soon increased the range of chemicals made. Due to the increased demand for polystyrene plastic for toys and electrical goods and so on, a styrene monomer plant was commissioned for Forth Chemicals (50% owned by Monsanto) in 1953. In 1955 a plant to make alkylate (used to make household synthetic detergents) was opened for Grange Chemicals (50% owned by a Standard Oils subsidiary).
1956 saw a second cracker and a second ethanol plant opened. The site had its own fire station and a research centre, keeping it at the forefront of new technology.
In 1959 BHC started production of thermoplastics with two new plants making novel High Density Polythene (HDPE) by the American Phillips solution process. HDPE was discovered in Germany and the USA in 1953-4. It was much more rigid than traditional Low Density Polythene, so BHC adopted the trade name "Rigidex". These plastics, able to be moulded by heat, changed the appearance of all sorts of everyday objects with bright colours easily incorporated.
Distillers' research Centre at Epsom invented some world-beating technologies, in particular the cumene-phenol process which started with benzene (from the refinery) and propylene. The product phenol was an essential starting material for the chemical and pharmaceutical industries. A plant was opened at Grangemouth in 1960, and the technology was licensed all round the world.
Other companies opened factories at Grangemouth using BHC products, In 1956 BHC started to extract butadiene from cracker products, and this chemical was used by the International Synthetic rubber Company (now Enichem) to make butyl rubbers in a factory beside the River Avon. The Bakelite Xylonite Company (BXL) made Low density Polythene in a factory on Inchyra Road. Opposite this, Marbon chemicals (later General Electric) used styrene, butadiene and acrylonitrile to make high-performance ABS copolymer plastics with engineering application (demolished 2010).
Further new BHC plant in the early 1960s included a methanol (wood alcohol) plant, and a third ethylene plant with capacity greater than the combined total of the previous two. A plant to make Acrlonite (AN) from propylene by Distillers' own solid-bed catalyst process was opened in 1965. AN sold to be made into polyacrylonitrile for synthetic fibre production. A second factory was opened by BHC at Baglan Bay in South Wales with a cracker and plants to make ethanol and ethylene dichloride, the latter being the starting material for making PVC plastics.
In 1967 BHC became wholly owned by the British Petroleum Company, which acquired most of DCL's chemical interests including at Hull. The name BP was adopted once more. In the early 1970s BP discovered the Forties Oil Field in the North Sea, and on-site plants subsequently grew at Grangemouth.