A big step toward ’green’ ammonia and a ’greener’ fertilizer

A chemical plant that produces ammonia, most of which goes into making fertilizer. Industrial production of ammonia, primarily for synthetic fertilizer - the fuel for last century's Green Revolution - is one of the world's largest chemical markets, but also one of the most energy intensive. Globally, the Haber-Bosch process for making ammonia uses about 1% of all fossil fuels and produces 1% of all carbon dioxide emissions, making it a major contributor to climate change. Now, University of California, Berkeley, chemists have taken a big step toward making ammonia production more environmentally friendly: a "greener" ammonia for "greener" fertilizer. A major stumbling block to making ammonia with less energy input has been separating the ammonia from the reactants - primarily nitrogen and hydrogen - without the large temperature and pressure swings required by the Haber-Bosch process. That reaction takes place between about 300 and 500 degrees Celsius, but ammonia is removed by cooling the gas to approximately -20 C, at which point the gaseous ammonia condenses as a liquid. The process also requires pressurizing the reactants to about 150'300 times atmospheric pressure.