Presentation on catalyst material used for production of ammonia.

1. 1.Introduction

2. Ammonia (NH3)
Applications .

3. Production of ammonia
U.S. = 8.2%
China = 28.4%
Russia = 8.4%
India= 8.6%

4. "I let the discovery of the ammonia
synthesis slip through my hands. It was
the greatest blunder of my scientific
career”
Henry Le Chatelier
Within less than five years of
Le Chatelier’s accident, Haber
started ammonia production
on large scale. The Nobel Prize
in Chemistry 1918 was awarded
to Fritz Haber "for the synthesis
of ammonia from its elements"
Haber and Bosch

5. 1.1 Need of Catalyst

6. Figure 1.1 Catalytic reaction path for ammonia
synthesis (Richardson, 1989).

7. Table 1.1: The worldwide increase
Ammonia capacity v/s process in ammonia production after
World population invention of economical Haber-Bosch
in 1927 (Lloyd, 2011).
Synthetic Ammonia capacity
200 Year World Synthetic
Synthetic Ammonia capacity (million tones year-1)
180
populati Ammonia capacity
160
140
on (million tones
120 (billions) year-1)
100
1804 1 -
80 Synthetic
Ammonia
capacity
1927 2 ~1
60
(million tones
40 year-1) - ~1 1960 3 1.6
20
1974 4 80
0
0 2 4 6 8 1987 5 145
World population (billions)
1999 6 175

8. 2. Catalyst Materials for
Ammonia Synthesis

9. Osmium Iron
Ruthenium
Cobalt

10. 2.1 Osmium:
Haber tested osmium, ammonia yield= 8%.
Under cyclic performance Os shows
activity equals to Ru.
Prepared by depositing K2[Os3(CO)13] on
Sibunit.

11. Table 2.1 Ammonia concentration and rate for Os and Ru catalyst.
Temperature = 250 to 400⁰C & Pressure = 1 atm

12. 2.2 Iron
Alwin Mittasch discovered iron
catalyst in 1909.
Magnetite from Sweden showed good
activity.
Alwin Mittasch
Iron with alumina and potassium
yielded a catalyst.

13. 2.1.1 Iron catalyst promoted by potassium.
Table 2.2 Ammonia concentration & rate for iron catalyst
Pressure = 1 atm.

14. 2.2.2 Catalyst based on Fe l – X O (wustite)
Highest activity, easiest reduction.
Stronger mechanical strength.
Low cost. Used in china
Prepared by melting magnetite mixture and cooling.

15. Figure 2.1 Relative activities of the catalysts. Pressure, 15 MPa;
space velocity, 30000 h-1. (1) A301 catalyst, (2) conventional catalyst
l, (3) conventional catalyst 2 (Liu et el., 1996).

16. 2.2.3 Iron catalyst doped with Lithium oxide.
Till 2009 Li2O is not an effective activator for Fe catalyst.
Figure 2.2 The influence of promoters on the activity of fused
iron catalyst for ammonia synthesis (Kuzniecov et al., 2009).

17. Figure 2.4 Relative activity of the catalysts measured at 450OC
(Walerian et al., 2009).

18. 2.3 Ruthenium
In 1990 KAAP used ruthenium on graphite support.
Higher surface area.
Higher activity at low pressure.
Prepared by subliming ruthenium-carbonyl onto carbon
coated support which is impregnated by rubidium nitrate.

19. 2.3.1 Ruthenium supported on carbon
coated alumina.
Graphite takes electron from alkali metal promoter and
transport them towards Ru.
Prepared by pyrolysis of an alkene on γ-Al2O3– drying– at
150⁰C u/vacuum for 8 h.
Ru: Cs: support ratio was kept10:51:100.

20. Table 2.3 BET surface areas of supports end ammonia
synthesis yields of cesium-promoted Ru catalysts (Rama
Rao et el., 1990).
Steady state NH3
BET surface area NH3 yield
Catalysts Supports conc. at 350⁰C
(m2 g-1) [cm3 h-1 g Ru-1]
[% (v/v)]
1 Carbon (SKT) 1350 0.005 2
2 Carbon (Subunit) 500 0.652 261
3 8% - Al2O3 220 0.670 268
4 24% - Al2O3 230 0.763 305
Temperature = 350⁰C & Pressure = 1 atm.
Thermodynamic equilibrium NH3 concentration at 350 C is 0.864%
(v/v).

21. Figure 2.5 Effect of reaction temperature on
the steady-state concentrations of ammonia
over cesium promoted supported ruthenium
catalysts. Symbols:
( ) catalyst 1: Cs-Ru/carbon (SKT),
(ο) catalyst 2: Cs-Ru/carbon (Subunit),
( ) catalyst 3: Cs-Ru/8% C-Al2O3 Also,
(Δ) catalyst 4: Cs-Ru/24% C-Al2O3
(Rama Rao et el., 1990).

22. 2.3.2 Ruthenium catalyst based on
supported K2 [Ru4 (CO)13].
The role of electron promoter in these catalysts is
played by potassium.
Replacement of ‘Sibunit’ carbon by usual commercial
active carbons resulted in a sharp decrease in activity
and stability of the catalysts.

23. Table 2.4 Experiment results of ammonia synthesis over Ru
supported on different supports (Yunusov et el., 1998).
Enhancement in the electron density on ruthenium atoms occurs
which favours the effective dinitrogen activation and, as a
consequence, the efficient work of the catalyst

24. 2.3.3 Ru-Ba/AC (Activated Carbon)
Catalyst Promoted by Magnesium.
MgO reduce the agglomeration of Ru at high
temperature, which increases available amount of Ru.
Size of Ru improved, increase the Ru surface area.
magnesium to Ru-Ba-K/AC significantly improved the
utilization ratio of the noble metals and the performance-
price ratio.

25. Table 2.5 Effect of Mg promoter on the activity of the Ru-Ba/AC
catalysts for ammonia synthesis (Jun et el., 2011).
Reaction conditions: 10 MPa, *KOH content: 18%.

26. 2.3.5 Iron catalyst and Ru catalyst in
series.
Iron catalyst followed by Ru used in KAAP.
Catalyst life increased.

27. Table 2.6. Ammonia concentration at different temperatures for
Ru catalyst and iron catalyst (Chonggenet et al., 2011).
Reaction conditions: 10 MPa, 10000 h-1, N2+3H2.

28. 2.4 Cobalt
High ammonia concentration corresponds to high
conversion.
Prepared by impregnation of cobalt nitrate and cerium
nitrate on AC, followed by evaporation and calcination.
Inorganic material to carbon matrix ration is kept auto
1.5:1.

29. Table 2.7 Activity of the promoted cobalt catalysts; T = 400⁰C, p =
63 bar, gas (3H2+N2) flow rate = 70 dm3 [STP] h-1, mi = 0.4 gCo3O4
(Raróg-Pilecka et el., 2007).
a After the additional overheating in 3H2+N2 at 520⁰C for 150 h.

30. 2.5 Photochemical synthesis of ammonia on
Mg/TiO2 catalyst system
Doping with metal ion improve absorption property of
catalyst.
Mg+-TiO2 enhanced photocatalytic effect compare to alone
TiO2
Efficiency of catalyst depend upon doping level of
Mg2+, mixing temperature & duration of heating.
Yields of ammonia increase with increase in pH.

31. Figure 2.6 Variation of the ammonia yields with time at
different magnesium dopant levels (doping temperature
500⁰C, doping time 2 h) (Ileperuma et al., 1990).

32. 3. Conclusion
Osmium showed activity for ammonia synthesis but not accepted
because of its drawbacks.
Iron was the first successful catalyst used. Li2O showed good
results.
Ruthenium is the second generation o catalyst, showed good
activity at low pressure.
Cobalt is good option for replacement of Ru, less costly.
Photocatalytic reactions are possible.

33. Thank you