Haber process for ammonia


Haber process The process for the direct synthesis of ammonia from and Hj over a catalyst.  [c.198]

The synthetic ammonia industry of the latter part of the twentieth century employs only the Haber-Bosch process (12—15), developed in Germany just before World War 1. Development of this process was aided by the concurrent development of a simple catalyzed process for the oxidation of ammonia to nitrate, needed at that time for the explosives industry. N2 and H2 are combined direcdy and equiUbrium is reached under appropriate operating conditions. The resultant gas stream contains ca 20% ammonia.  [c.83]

These pioneers understood the interplay between chemical equiUbrium and reaction kinetics indeed, Haber s research, motivated by the development of a commercial process, helped to spur the development of the principles of physical chemistry that account for the effects of temperature and pressure on chemical equiUbrium and kinetics. The ammonia synthesis reaction is strongly equiUbrium limited. The equiUbrium conversion to ammonia is favored by high pressure and low temperature. Haber therefore recognized that the key to a successful process for making ammonia from hydrogen and nitrogen was a catalyst with a high activity to allow operation at low temperatures where the equiUbrium is relatively favorable.  [c.161]

Catalysts are discovered to meet processing needs and opportunities, but the discovery of a catalytic appHcation to take advantage of some newly discovered material almost never occurs. Catalyst development is largely a matter of trial and error testing. The methodology was defined by Haber, Bosch, and Mittasch in the development of the ammonia synthesis process. Catalyst developers benefit from an extensive and diverse Hterature and often can formulate good starting points in a search for candidate catalysts by learning what has been used successfully for similar reactions. Deeper insights, such as would arise from understanding of the mechanistic details of a catalytic cycle, are usually not attainable the exceptions to this rule largely pertain to molecular catalysis, usually reactions occurring in solution. Fundamental insights were valuable in guiding the development of the process for chiral hydrogenation and that for methanol carbonylation, among others, but it would be inappropriate to infer that understanding of the fundamental chemistry led to straightforward design of the catalysts. Indeed, the initial working hypothesis about the chiral hydrogenation turned out to be incorrect. The more comphcated processes of surface catalysis are for the most part only partially understood even when the processes are estabUshed and extensive after-the-fact research has been done. Creative research in catalyst discovery and development is usually the result of intuition and partial understanding combined with efficient testing and serendipity. Researchers who are repeatedly successful in finding new and improved catalysts seem to recognize needs and opportunities and notice significant exceptions to expected patterns and reason inductively by imperfect analogies.  [c.183]

The modem process for manufacturing nitric acid depends on the catalytic oxidation of NH3 over heated Pt to give NO in preference to other thermodynamically more favour products (p. 423). The reaction was first systematically studied in 1901 by W. Ostwald (Nobel Prize 1909) and by 1908 a commercial plant near Bochum. Germany, was producing 3 tonnes/day. However, significant expansion in production depended on the economical availability of synthetic ammonia by the Haber-Bosch process (p. 421). The reactions occurring, and the enthalpy changes per mole of N atoms at 25 C are  [c.466]

Great quantities are required commercially for the fixation of nitrogen from the air in the Haber ammonia process and for the hydrogenation of fats and oils. It is also used in large quantities in methanol production, in hydrodealkylation, hydrocracking, and hydrodesulfurization. Other uses include rocket fuel, welding, producing hydrochloric acid, reducing metallic ores, and filling balloons.  [c.4]

The trisubstituted ammonia (tertiary amine) shown in Figure 4.10, in which all the substituents are different, has no symmetry element and is, therefore, chiral but there is an important proviso. The ammonia molecule itself is pyramidal and can invert, like an umbrella turning inside out. It does this so rapidly (in about 10 " s, see Section 6.2.5.4a) that it can, for the present purposes, be regarded as effectively planar. The rate of inversion of the molecule shown in Figure 4.10 depends strongly on the masses of the groups Ri, R2 and R3. The heavier they are the more likely inversion will be such a slow process that there is no feasible interconversion between the enantiomers. It is also possible that some of these tertiary amines are not chiral because they have a planar configuration about the nitrogen atom.  [c.81]

These examples existed prior to Ostwald s definition (1), ie, before the nature of catalysis was weU understood. But in 1850 Wilhelmy (3) made the first measurements of kinetics of catalytic reactions in an investigation of sugar inversion catalyzed by mineral acids. In the years foUowing Ostwald s definition, just as the principles of chemical equiUbrium and kinetics were becoming known, the field of catalysis became more quantitative and developed rapidly. Kinetics of surface catalyzed reactions were measured by Bodenstein (4) just after the turn of the century. The defining work that set the stage for modem catalytic technology was the development of the ammonia (qv) synthesis process by Haber, Bosch, Mittasch, and co-workers at BASF in Germany, beginning ca 1908 (1,5).  [c.161]

In 1914, while abundant in the atmosphere, natural supplies of nitrogen in manure and in deposits of sodium nitrate were insufficient to meet the demand of war The solution was the Haber process for producing ammonia (NHj) by heating hydrogen and nitrogen gas at high pressure. Hydrogen is obtained by decomposing water (HjO) using heat or electricity. Burning coke and water produces steam, carbon monoxide, and hydrogen (water gas). Water gas reacts with steam and a catalyst to yield more hydrogen, and carbon dioxide which is removed by water dissolution. The mixture of carbon monoxide and hydrogen is the synthesis gas for methanol as shown in Figure 7.2-1. IS ihe source of ammonia and methanol. The hydrogen for ammonia is obtained from the water-gas sliifE reaction. Originally the process used coke from coal or lignite (brown coal), but the.se has been replaced by petroleum products and natural gas.  [c.265]

The production of superphosphate (calcium hydrogenphosphate + calcium sulphate) for fertilisers is the biggest use of sulphuric acid. Second to this is the manufacture of ammonium sulphate from ammonia (by the Haber process). This is also a fertiliser. Other uses are conversion of viscose to cellulose in the manufacture of artificial silk, and so on pickling (removal of oxide) of metals before galvanising or electroplating manufacture of explosives, pigments and dyestuffs, as well as many other chemicals, for example hydrochloric acid refining of petroleum and sulphonation of oils to make detergents and in accumulators.  [c.300]

Ammonia and Hydrogen Production. The earliest route for manufacture of ammonia from nitrogen was the cyanamide process commercialized in Italy in 1906. In this process calcium carbide manufactured from coal was treated with nitrogen at 1000°C to form calcium cyanamide, CaCN2. The cyanamide was hydrolyzed with water affording ammonia and calcium carbonate. Production reached 140,000 t/yr in Germany in 1915, but this process was energy intensive and soon was displaced by the more efficient Bosch-Haber process. This process was developed by BASE and commercialized in 1913 and involves the high pressure reaction of nitrogen and hydrogen over an iron catalyst. Most of the world s hydrogen production is used in ammonia synthesis by the Bosch-Haber process. The hydrogen for ammonia synthesis generally is obtained from synthesis gas produced by steam  [c.164]

Essentially all the processes employed for ammonia synthesis are variations of the Haber-Bosch process developed in Germany from 1904—1913. One of the all-time breakthroughs of chemical technology, the synthesis process involves the catalytic reaction of a purified hydrogen—nitrogen mixture under high (14 to 70 MPa (2,030 to 10,150 psi)) pressure and temperature (400 to 600°C). The preferred catalysts consist of specially activated iron. The ammonia that forms is condensed by cooling with Hquefied ammonia the unreacted gases are recycled to the synthesis loop. In over 80% of the ammonia plants of the 1990s, the hydrogen—nitrogen feed mixture is prepared by a series of reactions known as steam reforming, for which the raw materials are steam, natural gas (methane), and air. Commercial plants have also been based on use of naphtha or coal (coke) as feedstock. AH facets of ammonia production are highly sophisticated engineering processes requiring both a high level of technical know-how and a large capital investment.  [c.216]

In contrast to the large industrial facihties required to produce ammonia economically, some microorganisms are capable of diazotrophy, ie, the abihty to use N2 gas as the sole source of nitrogen for growth. Only prokaryotes, ie, those living things without an organized nucleus (eubacteria, cyanobacteria, archebacteria, and actinomycetes) can perform biological nitrogen fixation, the result of which is the reduction of N2 to ammonia. Such bacteria can be either free-living, such as A tobacter and Clostridium, or symbiotic, like the rhizobia. The latter group, in tight associations with higher leguminous plants, are much more important agriculturally. In exchange for the fixed nitrogen supphed by the bacterium, the legume supphes a protective environment in the form of the root nodule and energy in the form of carbohydrate generated by photosynthesis. Thus renewable solar energy (qv) powers this fertilizer production system. Ammonia fertilizer from the Haber process involves energy costs in production, in transportation to the user, and in storage for what is usually a seasonal industry. As food demands increase and fossil fuel reserves deplete, the exploitation of biological nitrogen fixation becomes more and more attractive as an alternative to commercial fertilizer production. Research in this area ranges from employing molecular genetic techniques to engineer nonlegume cash crops such as com and wheat (see Wheat and other cereal grains) to fix enough N2 for its own requirements (see Genetic engineering), through the increased use of associative symbioses to the development of catalysts based on nitrogenase for N2-reducing processes.  [c.84]

Ammonium compounds were produced ia the 1890s on a large scale as by-product ammonium sulfate [7783-20-2] from coke oven gas. Coke oven gas also provided the feedstock for the Haber-Bosch process, the first technology to synthesize ammonia directiy from elemental hydrogen and nitrogen. The first commercial Haber-Bosch iastaHation went on stream ia 1913 at a Badische Anilin and Soda Fabtik (BASF) faciUty ia Ludwigshafen-Oppau, Germany. It had a design capacity of 30 metric tons per day. The successful commercialization of this process not only produced first-of-a-kiad high temperature and pressure equipment designs but also resulted ia the promoted iron catalyst which is essentially stiU used for ammonia synthesis.  [c.339]

Work for the next 20 years focused on purification of the extrinsic factor from Hver. The work was slow and tedious, because fractionation was guided by tests on pernicious anemia patients. The discovery (8) that l ctobacillus lactis Domerieqaiies Hver extracts for growth greatiy accelerated the isolation process. In 1948, groups at Merck (9) in the United States and Glaxo (10) in England reported isolation of vitamin B 2 (cyanocobalamin) as a crystalline, ted pigment. The clinical efficacy of this matenal in the treatment of pernicious anemia was rapidly estabUshed (11).  [c.107]

An even more effective homogeneous hydrogenation catalyst is the complex [RhClfPPhsfs] which permits rapid reduction of alkenes, alkynes and other unsaturated compounds in benzene solution at 25°C and 1 atm pressure (p. 1134). The Haber process, which uses iron metal catalysts for the direct synthesis of ammonia from nitrogen and hydrogen at high temperatures and pressures, is a further example (p. 421).  [c.43]

F. Haber s catalytic synthesis of NH3 developed in collaboration with C. Bosch into a large-scale industrial process by 1913. (Hater was awarded the 1918 Nobel Prize in Chemistry for the synthesis of ammonia from its elements Bosch shared the 1931 Nobel Prize for contributions to the invention and development of chemical high-pressure methods , the Hater synthesis of NH3 being the first high-pressure industrial process.)  [c.408]

A flow chart of a typical batch process is shown in Figure 9. The oxidizer most commonly used is ammonium perchlorate which is rigidly controlled for moisture, impurities, and particle size and shape, and may contain a flow additive such as tricalcium phosphate. Slow and high speed grinding are accomphshed by hammer mills which may be coupled to an air classifier to provide the range of particle size distributions required. Fluid energy pulverizers are also used. Typical particle size ranges from 3—9 p.m for micro atomizers to 20—160 p.m for micropulverizers. The oxidizer is blended, screened, and transferred to a storage hopper for subsequent use.  [c.48]

When this reaction was first discovered, a considerably higher (ca 1300°C) temperature was required than that used in the 1990s. Thus, until Haber discovered the appropriate catalyst, this process was not commercially attractive. As of this writing (ca 1995), the process suffers from the requirement for significant quantities of nonrenewable fossil fuels. Although ammonia itself is commonly used as a fertilizer in the United States, elsewhere the ammonia is often converted into soHd or Hquid fertilizers, such as urea (qv), ammonium nitrate or sulfate, and various solutions (see Ammonium COMPOUNDS).  [c.83]

The value of nitrogen compounds as an ingredient of mineral fertilizers was recognized ia 1840. Nitrogen is an essential element to plant growth and ammonia is the primary nitrogen source used ia fertilizers (qv). Until the early 1900s, the nitrogen source ia farm soils was entirely derived from natural sources from mineral resources such as CtuleaQ nitrates, from manure and the putrefaction of vegetable wastes and from ammonium sulfate from coal coking, seed meals, sewage sludges, and food processiag by-products. The synthesis of ammonia directiy from hydrogen [1333-74-0] (qv) and nitrogen [7727-37-9] (qv) on a commercial scale was pioneered by Haber and Bosch ia 1913, for which they were awarded Nobel prizes. Further developments ia economical, large scale ammonia production for fertilizers have made a significant impact on iacreases ia the world s food supply.  [c.335]

Vitamin [68-19-9] (1,2) is the generic name for a closely related group of substances of microbial origin. Although the last of the vitamins to be characterized, its history is a long one, dating from 1824 when Combe (3) proposed the relationship of pernicious anemia, a disease characterized by defective (megoblastic) red blood cell formation, to disorders of the digestive system. Additional study of pernicious anemia, ia particular the work of Addison (4), continued for over 100 years before Minot and Murphy (5) reported that a diet containing large quantities of raw Hver restored the normal level of ted blood cells ia patients with pernicious anemia. This clinical breakthrough was based on the findings of Whipple and Robscheit-Robbias (6) that hver was of benefit ia regeneration of blood ia anemic dogs. For this work, Whipple, Miaot, and Murphy were awarded the Nobel Prize ia medicine and physiology ia 1934.  [c.107]


See pages that mention the term Haber process for ammonia : [c.30]    [c.73]    [c.137]    [c.324]    [c.1553]    [c.29]    [c.53]   
Chemistry of Petrochemical Processes (2000) -- [ c.144 ]