How did ammonia production shift from coke-based hydrogen to petroleum and natural-gas sources?

The production of ammonia relies on the Haber-Bosch process, which requires large quantities of hydrogen. Historically, this hydrogen was primarily sourced from coke—derived from coal or lignite—through a water-gas reaction with steam.12345

Following World War I, the nitrogen industry began a gradual transition away from coke-based methods. By the mid-20th century, the industry shifted toward petroleum products as the primary fossil fuel source for hydrogen production. This evolution was driven by the versatility of hydrocarbon feedstocks and the development of more efficient catalytic processes, such as steam-hydrocarbon reforming.452

In recent decades, the industry has trended toward the use of natural gas as the preferred feedstock. Today, most of the world’s ammonia is synthesized using hydrogen derived from methane via catalytic processes. This shift reflects the economic and operational advantages of using natural gas and liquid petroleum fractions over traditional coal-based coke.465