April 2022

100th Anniversary

Industry Pioneers: Cracking technology, catalysts, polymers and zeolites

Donald Campbell, Eger Murphree, Homer Martin and Charles Tyson—often called the ‘Four Horsemen’—are credited with the landmark invention of fluid catalytic cracking (FCC).

Sharma, Sumedha, Hydrocarbon Processing Staff


Donald Campbell, Eger Murphree, Homer Martin and Charles Tyson—often called the ‘Four Horsemen’—are credited with the landmark invention of fluid catalytic cracking (FCC). The FCC process revolutionized the refining industry by providing an efficient process to increase the yield of high-octane gasoline from crude oil. Their invention was awarded a U.S. patent and described as ‘a method of and apparatus for contacting solids and gases.’1

During the late 1930s, Exxon Research & Engineering Co. (ER&E) was looking for ways to improve high-octane gasoline yield. Chemical engineering professors at MIT—Warren K. Lewis and Edwin R. Gilliland—suggested that a low-velocity gas flow through a powder may lift it enough to cause it to flow like a liquid.1 Campbell, Martin, Murphree and Tyson at ER&E focused on the idea of a fluidized catalyst to innovate a design that would ensure a steady and continuous cracking operation. This idea led the four inventors to design a fluidized solids reactor bed with a pipe transfer system between the reactor and regenerator unit in which the catalyst is decoked and regenerated for reuse. The solids (catalyst) and gases (vaporized oil) are in continuous contact as they move upward in fluidized flow while cracking occurs. The hydrocarbon chains are split into smaller pieces, and the cracked molecules are further distilled to produce gasoline, heating oil, fuel oil, propane, butane and chemical feedstocks that are instrumental in producing a variety of petrochemical products.

The four inventors developed the process in 1942, and the first commercial FCC facility went online on May 25, 1942.2 Their invention was not only extremely important but also timely, as it enabled refineries to produce and supply enough high-octane fuel to aid U.S. and Allied forces during World War 2 (WW2). FCC technology also led to the rapid buildup of butadiene production, which was used by ER&E for making synthetic butyl rubber, another technology that was vital during that era. The first commercial FCC plant processed 13,000 bpd of heavy oil, making 275,000 gal of gasoline.3 FCC is widely employed today around the world and continues to evolve as the market for high-performance clean fuel demand increases.

Donald Campbell was an American engineer who was always fascinated by inventing and solving problems. He attended Iowa State University, then MIT and the Harvard Business School. He worked for 25 yr at ER&E, with a total of 41 yr at Exxon. He retired as Assistant to the Vice President of New Areas of Research, with 30 patents to his credit.3

Eger Murphree, a graduate in chemistry and a teacher, joined Standard Oil of New Jersey (later ER&E) in 1930. With his phenomenal work at ER&E and as co-inventor of FCC technology, he rose to serve as the President of ER&E from 1947–1962.4 He is widely recognized as a leader in the field of synthetic toluene, butadiene and hydrocarbon synthesis, FCC and fluid hydroforming.4

Homer Martin was a chemical engineer who earned a BS degree from the Armour Institute and an MS and PhD from the University of Michigan. He joined ER&E in 1937 and became one of the most productive inventors, garnering 82 patents until his retirement in 1973.5

Charles Tyson received his BS and MS degrees in chemical engineering from MIT and joined ER&E in 1930. He was the Director of the Petroleum Development Division and later the Special Assistant to the Vice President of ER&E. His work, primarily focusing on petroleum processing, earned him more than 50 patents until his retirement in 1962.2


American research chemists J. Paul Hogan and Robert Banks discovered crystalline polypropylene (PP) and created a process for making high-density polyethylene (HDPE) while working at Phillips Petroleum in 1951.6 Their breakthrough invention, although serendipitous, was not accidental. In the wake of WW2 and diminishing oil demand, Phillips Petroleum was involved in concerted efforts to investigate the uses of natural gas liquids (NGLs). Hogan and Banks were studying processes by which propylene and ethylene could be converted to valuable gasoline-like materials, so they started investigating the use of catalysts to do so.

In June 1951, they were experimenting by adding a small amount of chromium oxide to a nickel oxide catalyst and fed propylene with a propane carrier through the catalyst-packed tube. While pure nickel oxide yielded the expected product of low-molecular weight hydrocarbons, the chromium-modified catalyst produced a white solid—a new material, crystalline PP. With this new discovery, they pivoted research efforts from gasoline to plastics and used the chromium catalyst to produce an ethylene polymer. Within a year, they created the process for making HDPE—the safest, hardest and most heat-resistant plastic created at the time using much lower operating pressure than branched low-density PE. Phillips launched their product as Marlex® in 1954.7 Their invention revolutionized the consumer plastics industry and launched Phillips, an oil company, as a manufacturer of polyolefin plastics. HDPE is extensively used in packaging, commodity plastics, toys, tools, furniture, auto parts and a variety of other applications.

Hogan received the Pioneer Chemist Award and is credited with 52 U.S. patents.8 Hogan and Banks together received the Perkin Medal in 1987, the Heroes of Chemistry award by the American Chemical Society in 1989 and were inducted into the National Inventors Hall of Fame in 2001.9


In 1953, German chemist Karl Ziegler employed a catalyst consisting of a mixture of titanium tetrachloride and an alkyl derivative of aluminum to create a high molecular weight, high melting point and straight-chain PE. His pioneering research with organometallic compounds, which made industrial production of high-quality PE possible, won him the 1963 Nobel Prize in Chemistry, which he shared with Giulio Natta.10

Ziegler’s research established new polymerization reactions; enabled the syntheses of durable, higher melting, unbranched polymers; and laid the groundwork for several useful industrial processes. He combined classical organic chemistry with physical and analytical experimental methods in his phenomenal work on polymerization reactions.

Ziegler began his work on carbon compounds and organometallic chemistry during his professorship at the University of Heidelberg, which he continued after joining as the Director of the Max-Planck-Institut in Mülheim in 1943.11 Between 1952 and 1953, Ziegler’s research group tested various organoaluminium compounds and discovered that nickel was the cause of the chain-ending reaction. They further investigated to find a reagent to suppress this chain termination reaction, which led them to discover that titanium, under mild atmospheric conditions, produced rigid, high-melting unbranched PE.

Besides his work with organometallic compounds, he is also known for his research in the field of radicals with trivalent carbon and synthesis of multi-membered ring systems, which earned him the Liebig medal in 1935.11 One of the many awards Ziegler received was the reputed Werner von Siemens Ring in 1960 for expanding the scientific knowledge of and the technical development of new synthetic materials.10 Ziegler was able to take his discovery to industrial markets. By 1958, he was reaping the benefits of approximately two dozen licenses.12


Giulio Natta, an Italian scientist and chemical engineer, extended Ziegler’s method to other olefins. Based on his own findings on the reaction mechanism of polymerization, he developed further variations of the Ziegler catalyst. For his contribution to the field of high polymers, he shared the Nobel Prize in Chemistry with Karl Ziegler in 1963.13 Commercial Ziegler-Natta catalysts include many mixtures of halides of transition metals, especially titanium, chromium, vanadium and zirconium, with organic derivatives of nontransition metals, particularly alkyl aluminum compounds.14

Natta’s early research career focused on studying solids by x-rays diffraction (XRD) and electron diffraction. He later employed the same expertise to study catalysts and the structure of high organic polymers. By 1938, he began investigating macromolecules—polymerization of olefins and the kinetics of subsequent concurrent reactions.15 In 1953, after he received financial aid from the large Italian chemical company Montecatini, he extended Ziegler’s research on organometallic catalysts to stereospecific polymerization.15 These studies led to the development of isotactic PP, a thermoplastic polymer of highly regular molecular structure with commercially important properties of high strength and a high melting point. In 1957, Montecatini produced this polymer on an industrial scale at their Ferrara plant.15 Natta’s creation was commercially marketed as a plastic material by the name of Moplen, as a synthetic fiber by the name of Meraklon, as a monofilament by the name of Merakrin, and as packing film by the name of Moplefan.15

Natta discovered new classes of polymers and used XRD to determine the exact arrangement of chains in the lattice of the new crystalline polymers he discovered. He created polymers with sterically ordered structure—isotactic, syndiotactic and di-isotactic polymers and linear nonbranched olefinic polymers and copolymers with an atactic structure.

Natta is also known for his later research that led to two different routes for the synthesis of new elastomers: by polymerization of butadiene into cis-1,4 polymers with a high degree of steric purity, and by copolymerization of ethylene with other a-olefins (propylene), originating extremely interesting materials such as saturated synthetic rubbers. Natta published 700 research papers of which about 500 focus on stereoregular polymers. He also received several awards and has many patents in different countries to his credit.15


Dr. Hermann Schnell was a German scientist at Bayer who discovered the synthesis reaction of a new plastic—polycarbonate from co-monomers bisphenol A and phosgene. The new thermoplastic polymer—polycarbonate—has superior strength, toughness and impact resistance. Despite its resistance to breaking and splintering, it is lightweight, mostly optically transparent and can be easily molded or thermoformed. Unlike most thermoplastics, it can undergo large plastic deformations without cracking or breaking. With these properties, it is used in a variety of daily applications such as construction materials; electronic, auto, aircraft and security components; and optical lenses.16

Schnell studied under Nobel laureate and chemist Herman Staudinger. Soon after graduating, he joined the research and development department at Bayer AG, Leverkusen, Germany. Shortly thereafter, he moved to the lab at Uerdingen where he and his research team discovered the synthesis reaction of polycarbonate. The official patent for polycarbonate synthesis was granted in 1953 and was registered under the brand name Makrolon® on April 2, 1955.17 Bayer started industrial-scale production of Makrolon® at its plant in Uerfingen, Germany in 1958.17

Schnell became the department leader at Bayer research at just 36 yr of age and was appointed department head of Bayer’s entire central research facility in Leverkusen in 1971. He retired from Bayer in 1975.17


Frederick W. Stavely was a chemical research scientist who is credited with the discovery of polyisoprene. Stavely was a researcher at the Firestone Tire & Rubber Co in 1953 where, while investigating the reaction of butyl lithium on butadiene, he discovered that the polymerization of isoprene with metallic lithium produced polyisoprene with high cis content. High cis content is indicative of enhanced strain crystallization, which is closer to natural rubber, also with high cis content. This discovery was important during WW2 because other synthetic compounds did not exhibit the crystallization effect that was achieved in Stavely’s process. Stavely served as Chairman of the American Chemical Society Rubber Division. In 1972, Stavely received the Charles Goodyear Medal in recognition of this discovery.19


Edith Marie Flanigen, an American chemist, is known for her synthesis of zeolites for molecular sieves. Molecular sieves are crystalline microporous structures with large internal void volumes and molecular-sized pores that can separate or filter complex mixtures, as well as function as catalysts for chemical reactions. These compounds find numerous applications in the refining and petrochemical industries.

Flanigen joined Union Carbide in 1952 and began working on molecular sieves in 1956.20 During her 42-yr career at Union Carbide and UOP, Flanigen invented or co-invented more than 200 novel synthetic materials but is best known for her substantial contributions to the development of zeolite Y, an aluminosilicate sieve used to make oil refining more efficient, cleaner and safer.21 Zeolite Y is essentially employed in the cracking of crude oil to produce commercially valuable products like gasoline and diesel in a cleaner and more efficient manner. Her invention finds application in purification and contaminant removal and can be used to make ethylene and propylene, which are important raw materials to the petrochemical industry.

Besides her work on molecular sieves, Flanigen co-invented a synthetic emerald and pioneered the use of mid-infrared spectroscopy for analyzing zeolite structures. She has been quoted to say that one of her strengths throughout her career has been her ability to discover new material and see it through to commercialization, from envisioning processes for manufacturing it on a large scale to developing it for industrial application.

Flanigen became the first woman to hold the position of Senior Corporate Research Fellow at Union Carbide in 1982. She retired in 1994 with 108 U.S. patents in the field of petroleum research and product development.21, 22

In 1992, she became the first woman to receive the prestigious Perkin medal, the most distinguished honor in applied chemistry.22 Flanigen was the recipient of the $100,000 Lemelson-MIT Lifetime Achievement Award in 2004 and was inducted into the National Inventors Hall of Fame in the same year.22 In 2014, President Obama presented Flanigen with the National Medal of Technology and Innovation for her contributions to science and technology.22 HP


Hydrocarbon Processing would like to thank several institutions, companies and websites for the use of archived images of industry pioneers. These include the National Inventors Hall of Fame, the MIT Museum, the Plastics Hall of Fame and The Nobel Prize.


  1. Wikipedia, “Fluid catalytic cracking,” online: https://en.wikipedia.org/wiki/Fluid_catalytic_cracking
  2. National Inventors Hall of fame, “Charles W. Tyson,” online: https://www.invent.org/inductees/charles-w-tyson
  3. National Inventors Hall of fame, “Donald L. Campbell,” online: https://www.invent.org/inductees/donald-l-campbell
  4. National Inventors Hall of fame, “Eger V. Murphree,” online: https://www.invent.org/inductees/eger-v-murphree
  5. National Inventors Hall of fame, “Homer Z. Martin,” online: https://www.invent.org/inductees/homer-z-martin
  6. National Inventors Hall of fame, “Robert Banks,” online: https://www.invent.org/inductees/robert-banks
  7. ACS, chemical landmarks, polypropylene, online: https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/polypropylene.html
  8. National inventors Hall of fame, “J. Paul Hogan,” online: https://www.invent.org/inductees/j-paul-hogan
  9. Wikipedia, “J. Paul Hogan,” online: https://en.wikipedia.org/wiki/J._Paul_Hogan
  10. Wikipedia, “Karl Ziegler,” online https://en.wikipedia.org/wiki/Karl_Ziegler
  11.  The Nobel Prize, “Karl Ziegler–biographical,” online: https://www.nobelprize.org/prizes/chemistry/1963/ziegler/biographical/
  12. Britannica, “Karl Ziegler,” online: https://www.britannica.com/biography/Karl-Ziegler
  13. Britannica, “Giulio Natta,” online: https://www.britannica.com/biography/Giulio-Natta
  14. Britannica, “Giulio Natta,” online: https://www.britannica.com/science/Ziegler-Natta-catalyst
  15. The Nobel Prize, “Giulio Natta–biographical,” online: https://www.nobelprize.org/prizes/chemistry/1963/natta/biographical/
  16. Wikipedia, “Polycarbonate,” online: https://en.wikipedia.org/wiki/Polycarbonate
  17. Plastics Hall of Fame, “Hermann Schnell,” online: https://www.plasticshof.org/members/hermann-schnell/
  18. Wikipedia, “Daniel Fox,” online: https://en.wikipedia.org/wiki/Daniel_Fox_(chemist)#LEXAN_patent
  19. Awards and Winners, “Frederick W. Stavely,” online: http://awardsandwinners.com/winner/?name=frederick-w.-stavely&mid=/m/0vxcgxz
  20. Wikipedia, “Edith M. Flanigen,” online: https://en.wikipedia.org/wiki/Edith_M._Flanigen
  21. National inventors Hall of fame, “Edith Flanigen,” online: https://www.invent.org/inductees/edith-flanigen
  22. Lemelson MIT, “Edith Flanigen, Zeolite Y” online: https://lemelson.mit.edu/resources/edith-flanigen

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