By the nature of technology, but mainly because some foundries have no facilities to capture and neutralize pollutants or because existing tools do not work on greening at design parameters, metal powders, oxides various metals, anhydrous sulfur dioxide and
sulfur trioxide, carbon oxides, etc.
One of those pathways, as you mention, first creates sulfurous acid that then reacts with oxygen to make sulfuric acid In the other set of reactions, sulfur dioxide reacts with oxygen to make
sulfur trioxide, which then reacts with water to create sulfuric acid.--Sid Perkins
Procter and Gamble's Alexandria plant in Pineville, Louisiana, converted from oleum to "just-in-time manufacturing" of
sulfur trioxide by installing a sulfur burning unit.
Fuel Tech's proprietary TIFI Targeted In-Furnace Injection program will be utilized to mitigate the formation of
sulfur trioxide, a hazardous by-product that results from the combustion of higher-sulfur coal in the presence of a selective catalytic reduction system (SCR) for nitrogen oxide control.
Desulfurization of petroleum oils was carried out with nitrogen oxides and oxygen to convert organic sulfur into
sulfur trioxide which was absorbed with concetrated sulfuric acid.
It also produced negligible sulfur dioxide to
sulfur trioxide conversion, less than 0.1 percent, versus the 2 percent to 5 percent typically seen with selective catalytic reduction technologies, which aggravates plume appearance and could require additional control equipment."
During this formation process, oxidized fuel sulfur (sulfur dioxide) is further oxidized to
sulfur trioxide which then, in combination with water, will form sulfuric acid.
Sulfuric acid, oleum, chlorosulfonic acid, fluorosulfonic acid, amidosulfonic acid, free
sulfur trioxide and its complexes, halogen derivatives of sulfuric acid, etc., form the first group of sulfonating agents derived from
sulfur trioxide.