With the advent of mass production and the First World War, the number of gasoline-powered vehicles increased dramatically, and the demand for gasoline grew accordingly. However, only a certain amount of gasoline could be obtained from crude oil through atmospheric and vacuum distillation processes. The first thermal cracking process was developed in 1913. Thermal cracking subjected heavy fuels to both pressure and intense heat, physically breaking their large molecules into smaller ones, producing additional gasoline and distillate fuels. A sophisticated form of thermal cracking, visbreaking, was developed in the late 1930s to produce more desirable and valuable products.

As higher-compression gasoline engines were developed, there was a demand for higher-octane gasoline with better anti-knock characteristics. The introduction of catalytic cracking and poly- merization processes in the mid- to late 1930s met this demand by providing improved gasoline yields and higher octane numbers. Alkylation, another catalytic process, was developed in the early 1940s to produce more high-octane aviation gasoline and petrochemical feedstocks, the starting materials, for explosives and synthetic rubber. Subsequently, catalytic isomerization was developed to convert hydrocarbons to produce increased quantities of alkylation feedstocks.

Following the Second World War, various reforming processes were introduced which improved gasoline quality and yield, and produced higher-quality products. Some of these involved the use of catalysts and/or hydrogen to change molecules and remove sulphur. Improved catalysts, and process methods such as hydrocracking and reforming, were developed throughout the 1960s to increase gasoline yields and improve anti-knock characteristics. These catalytic processes also produced molecules with a double bond (alkenes), forming the basis of the modern petrochemical industry.

Summary of the history of refining processing

YearProcess nameProcess purposeProcess by-products
1862Atmospheric distillationProduce keroseneNaphtha, tar, etc.
1870Vacuum distillationLubricants (original)
Cracking feedstocks (1930s)
Asphalt, residual
Coker feedstocks
1913Thermal crackingIncrease gasolineResidual, bunker fuel
1916SweeteningReduce sulphur and odourSulphur
1930Thermal reformingImprove octane numberResidual
1932HydrogenationRemove sulphurSulphur
1932CokingProduce gasoline base stocksCoke
1933Solvent extractionImprove lubricant viscosity indexAromatics
1935Solvent dewaxingImprove pour pointWaxes
1935Catalytic polymerizationImprove gasoline yield and octane numberPetrochemical feedstocks
1937Catalytic crackingHigher octane gasolinePetrochemical feedstocks
1939VisbreakingReduce viscosityIncreased distillate, tar
1940AlkylationIncrease gasoline octane and yieldHigh-octane aviation gasoline
1940IsomerizationProduce alkylation feedstockNaphtha
1942Fluid catalytic crackingIncrease gasoline yield and octanePetrochemical feedstocks
1950DeasphaltingIncrease cracking feedstockAsphalt
1952Catalytic reformingConvert low-quality naphthaAromatics
1954HydrodesulphurizationRemove sulphurSulphur
1956Inhibitor sweeteningRemove mercaptanDisulphides
1957Catalytic isomerizationConvert to molecules with high octane numberAlkylation feedstocks
1960HydrocrackingImprove quality and reduce sulphurAlkylation feedstocks
1974Catalytic dewaxingImprove pour pointWax
1975Residual hydrocrackingIncrease gasoline yield from residualHeavy residuals