Synthetic Ammonia. Feeding the World

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Rhoda Wilcox
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1 Synthetic Ammonia Feeding the World

2 Content the role played by nitrogen in the growth of plants the search for a synthetic source of nitrogen to meet global population explosion Haber s discovery of ammonia synthesis scale up by Bosch from the laboratory bench into full production modern production of ammonia and its use the good, the bad and the ugly

6 Nitrogen Fixing 1. Nitrogen-fixing bacteria turn nitrogen in the soil into nitrate 2. Nitrogen-fixing bacteria on some plant root nodules turn nitrogen into nitrate. (legumes) 3. Compounds containing ammonia occur in animal excretion and in dead animals. The ammonia turns into nitrite and there are nitrifying bacteria in the soil that turn nitrite (NO 2 ) into nitrate (NO 3 ). 4. Lightning can cause chemical reactions in the atmosphere that make nitrogen react with oxygen producing nitrous oxides.

8 GUANO

9 New sources of nutrients Three alternative sources of nitrogen became available: the recovery of by-product ammonia from the coking of coal the high temperature synthesis of cyanamide (CaCN 2 ) from calcium carbide and nitrogen the fixation of atmospheric nitrogen by electrical discharge, through the availability of cheap electricity (hydro sources)

10 Fritz Haber Fritz Haber was a German chemist of Jewish origin who received the Nobel Prize in Chemistry in 1918 for his development of the Haber process. Born: December 9, 1868, Wrocław, Poland Died: January 29, 1934, Basel, Switzerland

11 Ammonia Reaction Le Châtelier's Principle : When a system at equilibrium is subjected to change, in concentration, temperature, volume, or pressure, then the system readjusts itself to (partially) counteract the effect of the applied change and a new equilibrium is established. This principle is used to manipulate the outcomes of reversible reactions, often to increase the yield of reactions. From the law of equilibrium it follows that the higher the pressure, the more the equilibrium must shift to the ammonia side. Earlier experiments had also shown the pointlessness of exceeding dark red heat, i.e. about 600 C. It was found that a temperature of about 500 C had to be used at the highest possible pressure, which in practice meant at about atmospheres.

12 Haber s apparatus

Carl Bosch (27 August 1874 26 April 1940) was a German chemist and engineer and Nobel laureate in chemistry.

13 Carl Bosch (27 August April 1940) was a German chemist and engineer and Nobel laureate in chemistry. He was a pioneer in the field of high-pressure industrial chemistry and founder of IG Farben, at one point the world's largest chemical company. Carl Bosch

14 Bosch s Three Tasks Supply of raw materials, i.e. of the gases hydrogen and nitrogen, at a purity and lower price than hitherto possible Manufacture of effective and stable catalysts Construction of the production plant that has to operate at high pressures and temperatures

15 Scale-up Hydrogen water gas produced by the reaction of glowing coke with water vapour. C + H 2 O H 2 + CO Then further Hydrogen by reacting CO with steam over catalyst to give CO 2 and H 2

16 Scale-up Catalyst The original Haber Bosch reaction chambers used osmium as the catalyst. Haber noted uranium was superior but harder to obtain. Under Bosch's direction in 1909, the BASF researcher Alwin Mittasch discovered and prepared much less expensive iron-based catalyst; this is still used today. Subsequent tests showed that the activity of the catalyst may be increased by oxides or certain salts of alkalis and alkaline earth metals, (K 2 O, CaO, SiO 2, and Al 2 O 3.) which in turn can reduce substantially the pressure in the chamber.

17 Scale-up Production Process Challenges Limiting corrosion Achieving yield and energy efficiency Operating under high pressure Controlling the process

18 Scale-up Production Plant Corrosive hydrogen At high pressure and quite high temperature, carbon steel is invariably corroded by hydrogen. The long sought solution consisted in fitting a pressure bearing steel jacket internally with a quite thin lining of soft steel in such a way that as the hydrogen, which of course only diffuses, passes through the thin lining it is able to escape without building up pressure before it can attack the outer steel jacket at the high temperature.

19 Scale-up Production Plant Achieving yield and energy efficiency Multiple pass; each pass yields about 15%; circulation and further processing of unreacted gases gives accumulated yield of 97% With large scale plant, together with good heat exchange, heat losses offset by heat of reaction

20 Scale-up Production Plant High Pressures

every stoppage at a single point affects the entire plant.

21 Scale-up Production Plant Instruments for control One of the key requirements of the ammonia synthesis plant was to run it continuously, as every stoppage at a single point affects the entire plant. Also, the need to continuously monitor process conditions Gas density recorder Detection of traces of oxygen

22 A historical (1921) high-pressure steel reactor for production of ammonia via the Haber process is displayed at the Karlsruhe Institute of Technology, Germany

23 Oppau site after explosion 1921

24 The Leuna site near Merseburg around 1920

25 Modern ammonia production plant

26 New source of Gas feed Centrifugal compressors

28 Ammonia Synthesis Centrifugal Compressor

29 Modern Ammonia Process Flow Diagram

31 Ammonia Historical Production Trends

34 Good! Feeding the World Without ammonia based fertilisers, it would not have been possible to support the unprecedented numbers of people with diets whose adequacy is unmatched in history.

37 Good! Improving process technology The development of high pressure technologies, plant and equipment, which later enabled amongst others the first production of polyethylene by ICI, and the Fischer- Tropsch process for the manufacture of petrol by the gasification of coal The design and development of many instruments for the control of gas and gas/liquid processes The first design and operation of a continuous, as distinct from, a batch process operation.

38 The production of synthetic ammonia by Germany enabled it to sustain its war machine and to prolong the First World War. Bad Ammonia nitrate use in armaments

39 Bad Fertilizers as a source of ground and river pollution

40 Bad Energy demands Ammonia plants and their associated fertiliser plants are located near cheap sources of energy. Need for renewable sources: Hydrogen gas by electrolysis of water Bio energy from organic wastes (such as biomass or food-industry waste), using catalytic (thermal) reforming

41 The Ugly Haber s role in gas warfare

42 The Ugly The Victims

43 Clara Immerwahr (June 21, 1870 May 2, 1915) was a German chemist. She was the first woman to be awarded a doctorate in chemistry in Germany. She was also an active women's rights activist. [

44 Haber s Nobel Prize Certificate

45 Carl Bosch Receiving Nobel Prize in 1931

Cycles in Nature Standard 1 Objective 2:

Cycles in Nature Standard 1 Objective 2: Explain relationships between matter cycles and Energy a) use diagrams to trace the movement of matter through a cycle b) Explain how water is a limiting factor