Industrial Catalysis
Lecture for Makrokierunek
Lecture 8
Heterogeneous catalysis
Inorganinic Synthesis
Nikodem Kuźnik
Silesian University of Technology
Gliwice, Poland
Scope of the lecture
• Synthesis of ammonia
• Synthesis of nitric acid
• Synthesis of sulfuric acid
Introduction of ammonia synthesis
Bond energy –
944.7kJ/mol
N
N
Ionisation energy 1503 kJ/mol
- order of Ar, greater than O2
Haber, Mittasch,
1909
Fe
NH3
Dissociation on Fe, Cu, Ag,
Pt, Au known since 1813
Fe
N2 + 3H2
2NH3
Bosch designed reactor for 900K, 200 bar
Production of ammonia
Catalytic system
Active phase
(real catalyst)
Promotores:
-donate electrons
-suppression of S
adsorption
Promotore:
avoid Fe
sintering
Fe3O4
K2O
Al2O3
heated powders at 1873 K
On surface: Fe4N
Fe
N
N
Production of ammina
Industrial solutions
Uses of Ammonia and Nitric acid
Amonia NH3
Nitric acid HNO3
World annual production
appr. 140 million tonnes
World annual production
appr. 60 million tonnes
Production of nitric acid
90%Pt, 10% Rh
4 NH3 + 5 O2
2 NO + O2
3 NO2 + H2O
760oC
4 NO + 6 H2O
2NO2
N2O4
2HNO3 + NO
Industrial system types: signle- and dual-stage pressure
Nitric acid cataylst
Electron micrograph of
platinum/rhodium catalyst showing
large surface area of gauze.
Nitric acid
Ostwald method
Nitric Acid
Dual-pressure process
CW = Cooling water, WB = Boiler water / feedwater
History of sulfuric acid production
Old names for sulfuric acid: oil of vitriol, spirit of vitriol
Ibn Zakariya al-Razi, 9th century, Albertus Magnus:
FeSO4 • 7 H2O → n H2SO4 + m Fe2O3
green vitriol
CuSO4 • 5 H2O → n H2SO4 + m CuO
blue vitriol
J. Glauber, Roebuck 17-18th century, lead chamber process:
S + O2 + KNO3 + H2O (steam) → H2SO4 + ....
Gay-Lussac, Glover, 18th century, 78% acid:
FeS2 (pyrite) + O2 → FeSO4 → Fe2(SO4)3 → Fe2O3 + SO3
Sulfuric acid production
Mechanism
1. Solid sulfur, S(s), is burned in air to form sulfur dioxide gas, SO2
S(s) + O2(g) → SO2(g)
2. The gases are mixed with more air then cleaned by electrostatic
precipitation to remove any particulate matter
3. The mixture of sulfur dioxide and air is heated to 450oC and subjected
to a pressure of 101.3 - 202.6 kPa (1 -2 atmospheres) in the presence
of a vanadium catalyst to produce sulfur trioxide, SO3(g), with a
yield of 98%. Exrotermic reaction! Catalysts: Pt, V2O5, NO2
2SO2(g) + O2(g) → 2SO3(g)
4. Any unreacted gases from the above reaction are recylced back into
the above reaction
Sulfuric acid production
Absorption of SO3
5. Sulfur trioxide, SO3(g) is dissolved in 98% (18M) sulfuric acid, H2SO4, to
produce disulfuric acid or pyrosulfuric acid, also known as fuming sulfuric acid
or oleum, H2S2O7.
SO3(g) + H2SO4 → H2S2O7
6. This is done because when water is added directly to sulfur trioxide to
produce sulfuric acid
SO3(g) + H2O(l) → H2SO4(l)
the reaction is slow and tends to form a mist in which the particles refuse to
coalesce.
7. Water is added to the disulfuric acid, H2S2O7, to produce sulfuric acid, H2SO4
H2S2O7(l) + H2O(l) → 2H2SO4(l)
SO3 in H2SO4: oleum, fuming sulfuric acid, Nordhausen acid
Sulfuric acid production
Obtaining sulfur
Sulfuric acid production
Contact Process
Sulfuric acid production
Lead Chamber Process
Uses of Sulfuric Acid
•Fertilizer production – fluoroapatite is treated
with sulfuric acid to produce superphosphate
•Paper production
•Ore processing
•Wastewater processing
•Nitration – production of explosives
•Acid batteries
•Dehydrating agent