All description of s and sulfuric acid

1. Lecture Outline - Sulfuric Acid
- History of Manufacture Development
- Manufacture
- Oleum Production
- Heat Integration Issues / By-products
- Markets
- Usage in Caprolactam Manufacture

2. History of Manufacture of Sulfuric Acid
• One of the oldest industrially applied processes. Discovered by a
Persian alchemist in the tenth century.
• Saltpeter and sulfur were mixed in a glass container and burned in a
moist atmosphere. Acid was collected from the condensed vapors.
• In England, 1746, the lead chamber reactor was invented. This
invention allowed for higher production rates (<78%).
• In England, 1831, a patent was filed that described the oxidation of sulfur
dioxide over a platinum catalyst, the Contact Process. This new process
increased yields of reaction from 70 to above 95%.
• In 1913, BASF was granted a patent for the use of vanadium pentoxide
as a catalyst for the Contact Process
• By the 1930’s, vanadium pentoxide was becoming the dominate catalyst
used because of insensitivities to poisons and lower cost.
• In 1960 a patent application was filed by Bayer using the so called
double-catalyst process (double absorption).

3. Manufacture
Three Step Process
1) S + O2 SO2
2) SO2 + 1/2O2 SO3
3) SO3 + H2O H2SO4

4. Oxidation of Sulfur
1) S + O2 SO2
Air
93% H2SO4
Sulfur
10-12% SO2
Steam
Water
Primary Generation of SO2
-79% Combustion of Sulfur
-9% Recovery from Metallurgic Processes
- 5% Regeneration of Spent Acids
Process:
- Air drying tower with acid
- Sulfur is injected into burner
- Reaction Temperature 2000°F
- Exothermic reaction must be cooled
- Steam recovered

5. Oxidation of Sulfur Dioxide
Contact Process:
-Vanadium pentoxide
catalyst
- Exothermic Reaction
- Multiple Steps with
cooling in between
- Double absorption
- Heat integration
Gas
Cooling
SO3 Gas
SO2 Gas

6. Oxidation of Sulfur Dioxide
 Because of the large effect temperature plays on the reaction, multiple catalyst
layers are used, with cooling between each step.
 Additionally, as the partial pressure of SO3 increases, further reaction is limited.
 This is overcome by removing the SO3 after the third stage to drive the reaction
to completion.
Gas
Cooling
SO3 Gas
SO3 Gas
SO2 Gas
93% H2SO4
SO2 Gas

7. Oxidation of Sulfur Dioxide
• Kinetic Effects
- Oxidation of sulfur dioxide is slow and reversible
- The reaction requires a catalyst and 426.7°C temperatures
-The reaction is exothermic and sensitive to excessive heat
• Equilibrium Constant (The degree at which the reaction proceeds is temp. dependent)
log Kp = 4.956 - 4.678
T
T = absolute temp. in kelvin
Kp = equilibrium constant as a function of partial pressure of gases
Kp = ( PSO3 )
PSO2 PO2
0.5

8. Oxidation of Sulfur Dioxide
Temperature Profile
Gas
Cooling
SO3 Gas
SO3 Gas
SO2 Gas
93% H2SO4
SO2 Gas
75 C
200 C
430 C
510 C
125 C

9. Oxidation of Sulfur Dioxide
Temperature Profile

10. Oxidation of Sulfur Dioxide
Typical Catalyst Distribution
Catalyst
Bed
% Catalyst Conversion %
1 19.4 56
2 25.0 87
3 26.7 99.1
4 28.9 99.7

11. Overall Production Scheme

12. Oleum Production
 Sulfuric acid with additional SO3 absorbed
 20% Oleum contains 20% SO3 by weight in the oleum
 Common strengths of oleum are 20, 30, 40, 65 percent.
 To produce 20 and 30 percent oleum, only requires an additional
absorption tower.
 Oleum is used in reactions where water is excluded
SO3 + H2SO4 H2S2O7 (disulfuric acid)

13. Reaction By-products / Heat Integration
By-products
 57 to 64% of the energy input generates steam
 Steam energy is used to drive the turbine that supplies power to
the main air blower
 Additional steam remaining is tolled internally for other plant
operations
 SO2/SO3 is vented in small amounts and is federally regulated.
Heat Integration
 Steam is used to pre-heat and vapor from the absorption towers
used to cool
 Minimizes the cost of manufacturing to maximize the profit.

14. Production Considerations
 Metal corrosion is a big issue in the manufacture of sulfuric acid.
 Special alloy metals must be used to guard against excessive
corrosion.
Nickel, chromium, molybdenum, copper, an silicon are the most
important elements that enhance corrosion resistance of alloys.
 Important variables for corrosion
Concentration of the acid
Temperature of service
Speed of flow in pipes and
equipment
Alloy element make-up

15. World Production of Sulfuric Acid
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Asia
U.S.
Africa
Europe
F-USSR
Latin
Japan
Others
Mexico
Canada
Share (percent)

16. World Supply / Demand for Sulfuric Acid
(thousands of metric tons, 100% H2SO4)
0
50,000
100,000
150,000
200,000
250,000
1985
1988
1991
1994
1997
2000
Annual Capacity Production

17. Markets for Sulfuric Acid
 The fertilizer market is the largest U.S. single use for sulfuric acid and
consumes 50-65 percent of all produced.
 Second is the organic chemical industry. Production of plastics and
synthetic fibers are examples.
 Production of TiO2 consumes large quantities of sulfuric acid. TiO2 is a
white pigment used in paints and plastics.
 In the metal industry, sulfuric acid is used for pickling ferrous and non-
ferrous materials and in the recovery of copper, nickel, and zinc from
low-grade ores.
 Finally, the petroleum industry uses acid as a catalyst for various
reactions.

18. Acid Strengths
Associated End Uses
Percent
H2SO4 Uses
35.67 Storage batteries, electric utilities
62.18
69.65
77.67
Normal superphosphate and other fertilizers,
isopropyl and sec-butyl alcohols
80.00 Copper leaching
93.19
Phosphoric acid, tianium dioxide, steel pickling,
regenerating ion exchange resins of utilities
98-99 Chlorine drying, alkylation, boric acid
104.50
106.75
109.00 Explosives
111.25
113.50
114.63
Reagent manufacture, organic sulfonations,
blending with weaker acids
Surfactants, nitrations, hydrofluoric acid
Normal superphosphate and other fertilizers

19. Usage in Caprolactam Manufacture
Production and consumption figures for caprolactam manufacture
Caprolactam Production Rate 120,000 ton/yr
H2SO4 Consumption (100% Acid) 636 kg per ton of CPL
Oleum Consumption 1300kg per ton of CPL
Ammonium Sulfate Production 312,000 ton/yr