„The water–gas shift reaction (WGSR) describes the reaction of carbon monoxide and water vapor to form carbon dioxide and hydrogen: CO + H2O ⇌ CO2 + H. The water gas shift reaction was discovered by Italian physicist Felice Fontana in 1780. It was not until much later that the industrial value of this reaction was realized. Before the early 20th century, hydrogen was obtained by reacting steam under high pressure with iron to produce iron-oxide and hydrogen. With the development of industrial processes that required hydrogen, such as the Haber–Bosch ammonia synthesis, a less expensive and more efficient method of hydrogen production was needed. As a resolution to this problem, the WGSR was combined with the gasification of coal to produce hydrogen.” (from Wikipedia: Water–gas shift reaction)

Several very accourate reports/articles can be found about the water gas shift reaction in the internet. This is just a sample in www.sciencedirect.com

This important and commonly employed reaction is well known in the industry, but the inventors of the TCG gasification technology was reinvented and modified the former one. Due to this re-thinking and addition the efficiency of the entire technology grown up radically.