Sulfuric Acid

Sulfuric Acid is, by total tonnage, the single most heavily produced industrial chemical in the world, a position it holds because so many other industrial processes — fertiliser manufacture, metal processing, petroleum refining, and the production of countless other chemicals including several in our own catalogue — depend on it either as a direct reagent or as the acid base from which other reactive sulfur chemicals (oleum, chlorosulfonic acid, nitrosylsulfuric acid) are themselves made. Its strength as a strong mineral acid, combined with its low relative cost and the straightforward way it is manufactured and handled at scale, is what has made it the default acid of choice across such an unusually broad span of industry.

At room temperature it is a dense, colourless to slightly yellow, oily liquid, highly corrosive and strongly exothermic when diluted with water — a reaction that must always be carried out by adding acid to water, never the reverse, since adding water to concentrated acid can cause the heat of dilution to vaporise the water violently and spatter acid. It is supplied across several standard concentration grades, from dilute battery-acid strength up to 98% concentrated technical acid, each suited to different downstream uses.

Where it fits in the value chain

Sulfuric Acid's largest single use by volume is phosphate and other fertiliser manufacture, where it reacts with phosphate rock to produce phosphoric acid and various sulfate fertiliser salts. It is also essential to metal processing (pickling and ore leaching), petroleum refining (alkylation catalysis), battery manufacture (lead-acid battery electrolyte) and, closest to our own catalogue, as the direct parent acid from which oleum, chlorosulfonic acid and nitrosylsulfuric acid are manufactured, and as a process reagent in caprolactam's classical Beckmann-rearrangement route and numerous other organic syntheses.

Grades we supply

Chelora Chemicals offers Sulfuric Acid across 78%, 93% and 98% concentration grades in technical, fertiliser and battery grades, with higher-purity electronic grade available on request. Each grade is supplied with a batch-wise certificate of analysis covering concentration, iron content and colour.

Sulfuric Acid is produced industrially by the contact process: sulphur is burned in air to form sulphur dioxide, which is then catalytically oxidised, over a vanadium pentoxide catalyst at elevated temperature, to sulphur trioxide; the sulphur trioxide is finally absorbed into existing concentrated sulfuric acid (rather than directly into water, which would create an uncontrollable acid mist), forming additional sulfuric acid that is drawn off and diluted to the target commercial concentration. Catalytic conversion efficiency at the vanadium pentoxide stage is the main process lever affecting both yield and the plant's sulphur dioxide emissions, so modern plants run multiple catalytic conversion stages with intermediate absorption to push conversion as close to complete as practically achievable.

The sulphur feedstock itself is most commonly recovered elemental sulphur from petroleum refining and natural gas processing (via the Claus process), rather than mined native sulphur, reflecting how the broader petroleum industry has become the dominant source of the world's sulphur supply. Final concentration adjustment and quality control, including iron and heavy-metal trace-level checks for higher-purity grades, are carried out before packaging.