Praxair has developed numerous technologies that reduce emissions from our customers’ processes. For example, Praxair’s oxy-fuel combustion technology reduces nitrogen oxide and particulate emissions from burners used in glass and steel production. This technology is now being applied to coal-fired power-plant boilers. The U.S. Environmental Protection Agency has set new standards to reduce emissions from diesel and gasoline engines. To accomplish this, refiners must reduce the amount of sulfur contained in these fuels. Sulfur dioxide (SOx) not only forms sulfuric acid, it also harms a car’s catalytic converter, allowing nitrogen oxides to escape. Nitrogen oxide forms nitric acid which, along with sulfuric acid, is a primary constituent of acid rain.     Hydrogen removes sulfur from petroleum-based fuels by replacing a sulfur molecule with a hydrogen molecule on the carbon chain, forming hydrogen sulfide as a by-product. The hydrogen sulfide is typically processed into elemental sulfur, which has commercial value and can be resold.