Total Sulfur Analysis
Petroleum products like diesel, gasoline and fuel oil, may include many organic Sulfur compounds and can be classified as acidic and non-acidic. Acidic Sulfur compounds are mercaptans. Thiophene, sulfides, and disulfides are examples of non-acidic Sulfur compounds. These organic Sulfur compounds are products of the degradation of Sulfur containing biological components, present during the natural formation of the crude oil. Hydrogen sulfide is the main inorganic compound found in crude oil. Most Sulfur compounds can be removed from petroleum streams through hydrotreatment processes, where hydrogen sulfide is produced and the corresponding hydrocarbon released. Hydrogen sulfide is then absorbed in a suitable absorbent and recovered as Sulfur.
The Sulfur is being removed from petroleum distillates to reduce Sulfur dioxide (SO2) emissions when fossil fuels are combusted and in order to protect catalysts in the refining process against poisoning. To monitor the amount of Sulfur present in the crude, intermediates and final products, an elemental combustion analyzer is used to monitor the amount of Total Sulfur.
The latest environmental regulations like the TIER III and EURO V allows a maximum of 10 mg/kg of Total Sulfur or ppm weight in diesel oils. This maximum amount of 10 ppm is also included in the Chinese norms GB 19147-2013 for Diesel fuels and GB 17930-2013 for Gasoline, deriving from the CHINA 5 environmental program. The maximum allowable amount of Sulfur present in fuels demonstrates a global downward trend. This raises the importance of accurately measuring the total amount of Sulfur in petro (chemical) products at trace level.