Complex sentence: Typically, oil is desulfurized in refineries using a process, referred to as Hydrodesulfurization (HDS), involving the reaction of hydrogen with oil in the presence of a catalyst at high temperature, resulting in the removal of sulfur in the form of hydrogen sulfide gas.
Split into simpler sentences: Typically, oil is desulfurized in refineries using a process, referred to as Hydrodesulfurization (HDS). HDS involves the chemical reaction of hydrogen with oil in the presence of a catalyst at high temperature, resulting in the removal of sulfur in the form of hydrogen sulfide gas.