Inorganic technology

Inorganic technology

Sulfur and sulfur compounds Deposits: • Elemental sulfur in sedimentary or volcanic deposits • Sulfates • Sulfides • H2S in natural gas

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Sulfuric acid Principle of sulfuric acid manufacture

SO2 + 0,5 O2 → SO3 SO3 + H2O ( in H2SO4 )→ H2SO4

Manufacture of sulfur dioxide Starting material: • elemental sulfur S + O2 → SO2 • Pyrites 2 FeS2 + 5,5 O2 → Fe2O3 + 4 SO2 Temperature at least 800oC


Sulfuric acid SO2 + 1/2 O2 → SO3 Catalyst: divanadium (V) oxide – V2O5 Temperature: 420 to 440oC Contact process:

• Single • Double

Sulfuric acid Contact process:

• Single reaction gases are passed through the trays without intermediate absorption (maximum conversion 98 %)

• Double after 3rd tray removal of SO3 by absorption in 98.5 to 99 % H2SO4 (maximum conversion 99.6 to 99.7 %)


sulfur

Single contact process SO2 burner

air 1 catalyst coolers

5 SO3


sulfur

Double contact process SO2 burner

air cooler s

H2SO4

1 catalyst

Absorption tower

3

5 SO3

Sulfuric acid Moist gas catalysis process: 2 H2S + 3 O2 → 2 SO2 + 2 H2O SO2 + ½ O2 → SO3 (catalyst - V2O5)


Sulfur acid Applications of sulfur acid: manufacture of phosphorus and nitrogen fertilizers. petrochemical industry alkylations of isoalkanes with alkenes, manufacture inorganic chemicals hydrofluoric acid, chromic acid, aluminium sulfate organic products dyes, Explosives, isocyanates, soaps, detergents, fibers and pharmaceuticals manufacture of titanium oxide pigments, uranium and cooper extraction, in steel pickling and in batteries.

100 % sulfur dioxide In absorption processes sulfur dioxide is separated with a solvent from SO2 – containing gases. • Water at atmospheric pressure or increased pressure (5 bars) is used as an absorption agent for sulfur dioxide, the absorbed sulfur dioxide being subsequently expelled with steam. • In the condensation process sulfur dioxide from roasting sulfidic ores or combustion of sulfur are separated in liquid form by increasing the pressure to ca. 5 bars and cooling with countercurrent coolers, cooled with liquid ammonia. • Sulfur dioxide is formed by reacting sulfur with sulfur trioxide: 2 SO3 + S → 3 SO2 this is freed of sulfur trioxide by treatment with sulfuric acid.


Applications • • • • •

Manufacture of chemicals Cellulose production Dressing of ores Mineral oil processing Disinfection and preservation agent

100 % sulfur trioxide Pure sulfur trioxide is industrially produced from oleum by distillation in stainless steel falling film evaporators or forced circulation evaporators and liquefaction of the vapor. • Applications: • manufacture of chlorosulfonic acid, • thionyl chloride, aminosulfonic acid, • dimethyl sulfate • sulfonation of organic substances


Sulfurous acid salts Of the salts of sulfurous acid only the sodium salts and calcium hydrogen sulfite are industrially important. • Sodium hydrogen sulfite SO2 + NaOH → NaHSO3 • Sodium disulfite • Sodium sulfite

Hydrogen sulfide H2 + S → H2S • Temperature - 350o C • Catalysts-cobalt molybdenum oxide on γ Al2O3. Application: starting material for the manufacture of sodium hydrogen sulfide, sodium sulfite and organic sulfur compounds, such as thiophenes or thiols.


Sodium sulfite Na2SO4 + 2 C → Na2S + 2 CO2 Application: Sodium sulfite is mainly used in tanning as a hair – removing agent. It is also utilized in ore flotation, dyeing with sulfur dyes in the textile industry and in the chemical industry e.g. for the precipitation of heavy metal ions.


Inorganic technology

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