Hydrodesulfurization is a chemical process used to remove sulfur from petroleum products. This process is essential for producing cleaner fuels, as sulfur compounds can lead to air pollution and acid rain when burned. During hydrodesulfurization, hydrogen gas is combined with the sulfur-containing compounds in the presence of a catalyst, typically made from metals like cobalt or molybdenum. The process occurs at high temperatures and pressures, allowing the sulfur to be converted into hydrogen sulfide, which can then be easily separated from the fuel. By reducing sulfur content, hydrodesulfurization helps meet environmental regulations and improves the quality of fuels like gasoline and diesel.