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

Year Process name Process purpose Process by-products
1862 Atmospheric distillation Produce kerosene Naphtha, tar, etc.
1870 Vacuum distillation Lubricants (original)
Cracking feedstocks (1930s)
Asphalt, residual
Coker feedstocks
1913 Thermal cracking Increase gasoline Residual, bunker fuel
1916 Sweetening Reduce sulphur and odour Sulphur
1930 Thermal reforming Improve octane number Residual
1932 Hydrogenation Remove sulphur Sulphur
1932 Coking Produce gasoline base stocks Coke
1933 Solvent extraction Improve lubricant viscosity index Aromatics
1935 Solvent dewaxing Improve pour point Waxes
1935 Catalytic polymerization Improve gasoline yield and octane number Petrochemical feedstocks
1937 Catalytic cracking Higher octane gasoline Petrochemical feedstocks
1939 Visbreaking Reduce viscosity Increased distillate, tar
1940 Alkylation Increase gasoline octane and yield High-octane aviation gasoline
1940 Isomerization Produce alkylation feedstock Naphtha
1942 Fluid catalytic cracking Increase gasoline yield and octane Petrochemical feedstocks
1950 Deasphalting Increase cracking feedstock Asphalt
1952 Catalytic reforming Convert low-quality naphtha Aromatics
1954 Hydrodesulphurization Remove sulphur Sulphur
1956 Inhibitor sweetening Remove mercaptan Disulphides
1957 Catalytic isomerization Convert to molecules with high octane number Alkylation feedstocks
1960 Hydrocracking Improve quality and reduce sulphur Alkylation feedstocks
1974 Catalytic dewaxing Improve pour point Wax
1975 Residual hydrocracking Increase gasoline yield from residual Heavy residuals