Short answers, pulled from the story.
George E. Davis, an English consultant born in 1850, gave the profession its name. He never built a single chemical plant yet recognized the need for a professional to bridge the gap between the laboratory bench and the massive industrial reactor. By 1910, the title chemical engineer was in common use in both Britain and the United States.
Chemical engineering became a distinct field by 1910 when the title chemical engineer was in common use in both Britain and the United States. Before 1890, the term chemical engineering did not exist as a distinct field and the work was simply lumped into chemistry or mechanical engineering. Davis attempted to found a Society of Chemical Engineering but the industry was not ready for such a specific title.
World War II forced chemical engineers to abandon the old concept of unit operations in favor of developing complex chemical reactors. This shift created a second paradigm in the field introducing transport phenomena which provided an analytical approach to how fluids, heat, and mass moved through systems. The war also birthed biochemical engineering which allowed for the mass production of life-saving antibiotics like penicillin and streptomycin.
The 1974 Flixborough disaster in the United Kingdom proved that the pursuit of efficiency could lead to catastrophe when safety was ignored. This tragedy was part of a growing pattern of industrial failures that included the 1984 Bhopal disaster in India which resulted in at least 4,000 deaths. These events along with the publication of Silent Spring in 1962 which exposed the dangers of DDT forced the industry to confront its environmental and human costs.
Computer science became a fundamental tool for the profession replacing manual calculations and hand-drawn diagrams with sophisticated software like Aspen HYSYS. These programs allowed engineers to complete multiple chemical engineering calculations simultaneously simplifying the design and management of complex plants. The ability to model fluid dynamics heat transfer and mass transfer at the molecular level meant that engineers could predict the behavior of a system before a single piece of equipment was built.