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65-831: The Haber process , also called the Haber–Bosch process , is the main industrial procedure for the production of ammonia . It converts atmospheric nitrogen (N 2 ) to ammonia (NH 3 ) by a reaction with hydrogen (H 2 ) using finely divided iron metal as a catalyst: N 2 + 3 H 2 ↽ − − ⇀ 2 NH 3 Δ H 298   K ∘ = − 92.28   kJ / mol {\displaystyle {\ce {N2 + 3H2 <=> 2NH3}}\qquad {\Delta H_{\mathrm {298~K} }^{\circ }=-92.28~{\ce {kJ/mol}}}} This reaction

130-490: A hydrogen economy some hydrogen production could be diverted to feedstock use. For example, in 2002, Iceland produced 2,000 tons of hydrogen gas by electrolysis , using excess power from its hydroelectric plants, primarily for fertilizer. The Vemork hydroelectric plant in Norway used its surplus electricity output to generate renewable nitric acid from 1911 to 1971, requiring 15 mWh/ton of nitric acid. The same reaction

195-482: A pressure of 250 to 350 bar, a temperature of 450 to 550 °C and α iron are optimal. The catalyst ferrite (α-Fe) is produced in the reactor by the reduction of magnetite with hydrogen. The catalyst has its highest efficiency at temperatures of about 400 to 500 °C. Even though the catalyst greatly lowers the activation energy for the cleavage of the triple bond of the nitrogen molecule, high temperatures are still required for an appropriate reaction rate. At

260-523: A triple bond , which makes it relatively inert. Yield and efficiency are low, meaning that the ammonia must be extracted and the gases reprocessed for the reaction to proceed at an acceptable pace. This step is known as the ammonia synthesis loop: The gases (nitrogen and hydrogen) are passed over four beds of catalyst , with cooling between each pass to maintain a reasonable equilibrium constant . On each pass, only about 15% conversion occurs, but unreacted gases are recycled, and eventually conversion of 97%

325-639: A capacity of 544 m.t./day. It used a single-train design that received the “Kirkpatrick Chemical Engineering Achievement Award” in 1967. The plant used a four-case centrifugal compressor to compress the syngas to a pressure of 152 bar Final compression to an operating pressure of 324 bar occurred in a reciprocating compressor. Centrifugal compressors for the synthesis loop and refrigeration services provided significant cost reductions. Almost every plant built between 1964 and 1992 had large single-train designs with syngas manufacturing at 25–35 bar and ammonia synthesis at 150–200 bar. Braun Purifier process plants utilized

390-474: A catalyst and pursued more efficient formation. This method is implemented in a small plant for ammonia synthesis in Japan. In 2019, Hosono's group found another catalyst, a novel perovskite oxynitride-hydride BaCeO 3− x N y H z , that works at lower temperature and without costly ruthenium. The major source of hydrogen is methane . Steam reforming of natural gas extracts hydrogen from methane in

455-468: A certain content in order not to reduce the partial pressure of the reactants too much. To remove the inert gas components, part of the gas is removed and the argon is separated in a gas separation plant . The extraction of pure argon from the circulating gas is carried out using the Linde process . Modern ammonia plants produce more than 3000 tons per day in one production line. The following diagram shows

520-467: A commercial CO 2 shortage, thus limiting production of CO 2 -based products such as beer and soft drinks. This situation repeated in September 2021 due to a 250-400% increase in the wholesale price of natural gas over the course of the year. Robert Le Rossignol Robert Le Rossignol (27 April 1884 – 26 June 1976) was a British chemist. He is most known for his work with Fritz Haber on

585-476: A gradient of iron(II) ions, whereby these diffuse from the magnetite through the wüstite to the particle surface and precipitate there as iron nuclei. A high-activity novel catalyst based on this phenomenon was discovered in the 1980s at the Zhejiang University of Technology and commercialized by 2003. Pre-reduced, stabilized catalysts occupy a significant market share . They are delivered showing

650-404: A gradual increase in temperature. The reduction of fresh, fully oxidized catalyst or precursor to full production capacity takes four to ten days. The wüstite phase is reduced faster and at lower temperatures than the magnetite phase (Fe 3 O 4 ). After detailed kinetic, microscopic, and X-ray spectroscopic investigations it was shown that wüstite reacts first to metallic iron. This leads to

715-401: A high-temperature and pressure tube inside a reformer with a nickel catalyst. Other fossil fuel sources include coal, heavy fuel oil and naphtha . Green hydrogen is produced without fossil fuels or carbon dioxide emissions from biomass , water electrolysis and thermochemical (solar or another heat source) water splitting. Starting with a natural gas ( CH 4 ) feedstock,

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780-402: A large recycle stream is required. This can lead to the accumulation of inerts in the gas. Nitrogen gas (N 2 ) is unreactive because the atoms are held together by triple bonds . The Haber process relies on catalysts that accelerate the scission of these bonds. Two opposing considerations are relevant: the equilibrium position and the reaction rate . At room temperature, the equilibrium

845-543: A matter of months without it. Synthetic ammonia from the Haber process was used for the production of nitric acid , a precursor to the nitrates used in explosives. The original Haber–Bosch reaction chambers used osmium as the catalyst , but this was available in extremely small quantities. Haber noted that uranium was almost as effective and easier to obtain than osmium. In 1909, BASF researcher Alwin Mittasch discovered

910-539: A more complete separation of ammonia has been proposed by absorption in metal halides , metal-organic frameworks or zeolites . Such a process is called an absorbent-enhanced Haber process or adsorbent-enhanced Haber–Bosch process . The steam reforming, shift conversion, carbon dioxide removal , and methanation steps each operate at absolute pressures of about 25 to 35 bar, while the ammonia synthesis loop operates at temperatures of 300–500 °C (572–932 °F) and pressures ranging from 60 to 180 bar depending upon

975-573: A much less expensive iron-based catalyst that is still used. A major contributor to the discovery of this catalysis was Gerhard Ertl . The most popular catalysts are based on iron promoted with K 2 O , CaO , SiO 2 , and Al 2 O 3 . During the interwar years , alternative processes were developed, most notably the Casale process, the Claude process, and the Mont-Cenis process developed by

1040-454: A primary or tubular reformer with a low outlet temperature and high methane leakage to reduce the size and cost of the reformer. Air was added to the secondary reformer to reduce the methane content of the primary reformer exit stream to 1–2%. Excess nitrogen and other impurities were erased downstream of the methanator. Because the syngas was essentially free of impurities, two axial-flow ammonia converters were used. In early 2000 Uhde developed

1105-433: A process that enabled plant capacities of 3300 mtpd and more. The key innovation was a single-flow synthesis loop at medium pressure in series with a conventional high-pressure synthesis loop. In April 2017, Japanese company Tsubame BHB implemened a method of ammonia synthesis that could allow economic production at scales 1-2 orders of magnitude below than ordinary plants with utilizing electrochemical catalyst. In 2024,

1170-480: A shell of wüstite , which in turn is surrounded by an outer shell of metallic iron. The catalyst maintains most of its bulk volume during the reduction, resulting in a highly porous high-surface-area material, which enhances its catalytic effectiveness. Minor components include calcium and aluminium oxides , which support the iron catalyst and help it maintain its surface area. These oxides of Ca, Al, K, and Si are unreactive to reduction by hydrogen. The production of

1235-457: Is achieved. Due to the nature of the (typically multi-promoted magnetite ) catalyst used in the ammonia synthesis reaction, only low levels of oxygen-containing (especially CO, CO 2 and H 2 O) compounds can be tolerated in the hydrogen/nitrogen mixture. Relatively pure nitrogen can be obtained by air separation , but additional oxygen removal may be required. Because of relatively low single pass conversion rates (typically less than 20%),

1300-746: Is carried out by lightning, providing a natural source of soluble nitrates. Natural gas remains the lowest cost method. Wastewater is often high in ammonia. Because discharging ammonia-laden water into the environment damages marine life, nitrification is often necessary to remove the ammonia. This may become a potentially sustainable source of ammonia given its abundance. Alternatively, ammonia from wastewater can be sent into an ammonia electrolyzer (ammonia electrolysis ) operating with renewable energy sources to produce hydrogen and clean water. Ammonia electrolysis may require much less thermodynamic energy than water electrolysis (only 0.06 V in alkaline media). Another option for recovering ammonia from wastewater

1365-890: Is evident in the equilibrium relationship: K = y NH 3 2 y H 2 3 y N 2 ϕ ^ NH 3 2 ϕ ^ H 2 3 ϕ ^ N 2 ( P ∘ P ) 2 , {\displaystyle K={\frac {y_{{\ce {NH3}}}^{2}}{y_{{\ce {H2}}}^{3}y_{{\ce {N2}}}}}{\frac {{\hat {\phi }}_{{\ce {NH3}}}^{2}}{{\hat {\phi }}_{{\ce {H2}}}^{3}{\hat {\phi }}_{{\ce {N2}}}}}\left({\frac {P^{\circ }}{P}}\right)^{2},} where ϕ ^ i {\displaystyle {\hat {\phi }}_{i}}

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1430-403: Is expensive: pipes, valves, and reaction vessels need to be strong enough, and safety considerations affect operating at 20 MPa. Compressors take considerable energy, as work must be done on the (compressible) gas. Thus, the compromise used gives a single-pass yield of around 15%. While removing the ammonia from the system increases the reaction yield, this step is not used in practice, since

1495-422: Is in favor of ammonia, but the reaction does not proceed at a detectable rate due to its high activation energy. Because the reaction is exothermic , the equilibrium constant decreases with increasing temperature following Le Châtelier's principle . It becomes unity at around 150–200 °C (302–392 °F). Above this temperature, the equilibrium quickly becomes unfavorable at atmospheric pressure, according to

1560-560: Is most often produced through gasification of carbon-containing material, mostly natural gas, but other potential carbon sources include coal, petroleum, peat, biomass, or waste. As of 2012, the global production of ammonia produced from natural gas using the steam reforming process was 72%, however in China as of 2022 natural gas and coal were responsible for 20% and 75% respectively. Hydrogen can also be produced from water and electricity using electrolysis : at one time, most of Europe's ammonia

1625-412: Is obtained from finely ground iron powder, which is usually obtained by reduction of high-purity magnetite (Fe 3 O 4 ). The pulverized iron is oxidized to give magnetite or wüstite (FeO, ferrous oxide) particles of a specific size. The magnetite (or wüstite) particles are then partially reduced, removing some of the oxygen . The resulting catalyst particles consist of a core of magnetite, encased in

1690-450: Is the dissociative adsorption of nitrogen (i. e. the nitrogen molecule must be split into nitrogen atoms upon adsorption). If the binding of the nitrogen is too strong, the catalyst is blocked and the catalytic ability is reduced (self-poisoning). The elements in the periodic table to the left of the iron group show such strong bonds. Further, the formation of surface nitrides makes, for example, chromium catalysts ineffective. Metals to

1755-439: Is the fugacity coefficient of species i {\displaystyle i} , y i {\displaystyle y_{i}} is the mole fraction of the same species, P {\displaystyle P} is the reactor pressure, and P ∘ {\displaystyle P^{\circ }} is standard pressure, typically 1 bar (0.10 MPa). Economically, reactor pressurization

1820-565: Is thermodynamically favorable at room temperature, but the kinetics are prohibitively slow. At high temperatures at which catalysts are active enough that the reaction proceeds to equilibrium, the reaction is reactant-favored rather than product-favored. As a result, high pressures are needed to drive the reaction forward . Because ammonia production depends on a reliable supply of energy , fossil fuels are often used, contributing to climate change when they are combusted and create greenhouse gasses . Ammonia production also introduces nitrogen into

1885-406: Is thermodynamically favorable at room temperature, but the kinetics are prohibitively slow. At high temperatures at which catalysts are active enough that the reaction proceeds to equilibrium, the reaction is reactant-favored rather than product-favored. As a result, high pressures are needed to drive the reaction forward . The German chemists Fritz Haber and Carl Bosch developed the process in

1950-411: Is to use the mechanics of the ammonia-water thermal absorption cycle. Ammonia can thus be recovered either as a liquid or as ammonium hydroxide. The advantage of the former is that it is much easier to handle and transport, whereas the latter has commercial value at concentrations of 30 percent in solution. Making ammonia from coal is mainly practised in China, where it is the main source. Oxygen from

2015-464: The BBC announced numerous companies were attempting to reduce the 2% of global carbon dioxide emissions caused by the use/production of ammonia by producing the product in labs. The industry has become known as " green ammonia ." One of the main industrial byproducts of ammonia production is CO 2 . In 2018, high oil prices resulted in an extended summer shutdown of European ammonia factories causing

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2080-545: The Friedrich Uhde Ingenieurbüro. Luigi Casale and Georges Claude proposed to increase the pressure of the synthesis loop to 80–100  MPa (800–1,000  bar ; 12,000–15,000  psi ), thereby increasing the single-pass ammonia conversion and making nearly complete liquefaction at ambient temperature feasible. Claude proposed to have three or four converters with liquefaction steps in series, thereby avoiding recycling. Most plants continue to use

2145-547: The Nobel Prize in Chemistry : Haber in 1918 for ammonia synthesis specifically, and Bosch in 1931 for related contributions to high-pressure chemistry . During the 19th century, the demand rapidly increased for nitrates and ammonia for use as fertilizers, which supply plants with the nutrients they need to grow, and for industrial feedstocks. The main source was mining niter deposits and guano from tropical islands. At

2210-490: The Van 't Hoff equation . Lowering the temperature is unhelpful because the catalyst requires a temperature of at least 400 °C to be efficient. Increased pressure favors the forward reaction because 4 moles of reactant produce 2 moles of product, and the pressure used (15–25 MPa (150–250 bar; 2,200–3,600 psi)) alters the equilibrium concentrations to give a substantial ammonia yield. The reason for this

2275-627: The Earth's nitrogen cycle, causing imbalances that contribute to environmental issues such as algae blooms. Certain production methods prove to have less of an environmental impact, such as those powered by renewable or nuclear energy. Sustainable production is possible by using non-polluting methane pyrolysis or generating hydrogen by water electrolysis with renewable energy sources. Thyssenkrupp Uhde Chlorine Engineers expanded its annual production capacity for alkaline water electrolysis to 1 gigawatt of electrolyzer capacity for this purpose. In

2340-560: The Haber process at a laboratory scale. They demonstrated their process in the summer of 1909 by producing ammonia from the air, drop by drop, at the rate of about 125 mL (4 US fl oz) per hour. The process was purchased by the German chemical company BASF , which assigned Carl Bosch the task of scaling up Haber's tabletop machine to industrial scale. He succeeded in 1910. Haber and Bosch were later awarded Nobel Prizes, in 1918 and 1931 respectively, for their work in overcoming

2405-797: The Haber–Bosch process, is the main industrial procedure for the production of ammonia. It converts atmospheric nitrogen (N 2 ) to ammonia (NH 3 ) by a reaction with hydrogen (H 2 ) using finely divided iron metal as a catalyst: N 2 + 3 H 2 ↽ − − ⇀ 2 NH 3 Δ H 298   K ∘ = − 92.28   kJ / mol {\displaystyle {\ce {N2 + 3H2 <=> 2NH3}}\qquad {\Delta H_{\mathrm {298~K} }^{\circ }=-92.28~{\ce {kJ/mol}}}} This reaction

2470-586: The KBR Advanced Ammonia Process (KAAP) since 1992. The carbon carrier is partially degraded to methane ; however, this can be mitigated by a special treatment of the carbon at 1500 °C, thus prolonging the catalyst lifetime. In addition, the finely dispersed carbon poses a risk of explosion. For these reasons and due to its low acidity , magnesium oxide has proven to be a good choice of carrier. Carriers with acidic properties extract electrons from ruthenium, make it less reactive, and have

2535-402: The air separation module is fed to the gasifier to convert coal into synthesis gas ( H 2 , CO, CO 2 ) and CH 4 . Most gasifiers are based on fluidized beds that operate above atmospheric pressure and have the ability to utilize different coal feeds. The American Oil Co in the mid-1960s positioned a single-converter ammonia plant engineered by M. W. Kellogg at Texas City, Texas, with

2600-444: The beginning of the 20th century these reserves were thought insufficient to satisfy future demands, and research into new potential sources of ammonia increased. Although atmospheric nitrogen (N 2 ) is abundant, comprising ~78% of the air, it is exceptionally stable and does not readily react with other chemicals. Haber, with his assistant Robert Le Rossignol , developed the high-pressure devices and catalysts needed to demonstrate

2665-433: The catalyst requires a particular melting process in which used raw materials must be free of catalyst poisons and the promoter aggregates must be evenly distributed in the magnetite melt. Rapid cooling of the magnetite, which has an initial temperature of about 3500 °C, produces the desired precursor. Unfortunately, the rapid cooling ultimately forms a catalyst of reduced abrasion resistance. Despite this disadvantage,

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2730-403: The catalyst through recrystallization , especially in conjunction with high temperatures. The vapor pressure of the water in the gas mixture produced during catalyst formation is thus kept as low as possible, target values are below 3 gm. For this reason, the reduction is carried out at high gas exchange, low pressure, and low temperatures. The exothermic nature of the ammonia formation ensures

2795-665: The chemical and engineering problems of large-scale, continuous-flow, high-pressure technology. Ammonia was first manufactured using the Haber process on an industrial scale in 1913 in BASF's Oppau plant in Germany, reaching 20 tonnes/day in 1914. During World War I , the production of munitions required large amounts of nitrate. The Allied powers had access to large deposits of sodium nitrate in Chile (Chile saltpetre ) controlled by British companies. India had large supplies too, but it

2860-505: The decomposition of triruthenium dodecacarbonyl on graphite . A drawback of activated-carbon-supported ruthenium-based catalysts is the methanation of the support in the presence of hydrogen. Their activity is strongly dependent on the catalyst carrier and the promoters. A wide range of substances can be used as carriers, including carbon , magnesium oxide , aluminium oxide , zeolites , spinels , and boron nitride . Ruthenium-activated carbon-based catalysts have been used industrially in

2925-403: The difficult problem of demonstrating ammonia synthesis from air, eventually producing a tabletop apparatus that worked at 200 atmospheres pressure. Haber was awarded the Nobel Prize for his discovery that virtually "made bread from the air" and recognized the assistance he'd received from Le Rossignol, whose name appears on Haber's patents for the process. He was interned in Germany in 1914 at

2990-471: The first decade of the 20th century, and its improved efficiency over existing methods such as the Birkeland-Eyde and Frank-Caro processes was a major advancement in the industrial production of ammonia. The Haber process can be combined with steam reforming to produce ammonia with just three chemical inputs: water, natural gas, and atmospheric nitrogen. Both Haber and Bosch were eventually awarded

3055-752: The fixation of nitrogen from atmospheric air, the Haber process . He was born in Saint Helier , Jersey , Channel Islands , and attended school there. He matriculated from the University of London in 1901 and graduated from University College London in 1905 where he remained, becoming a member of the Institute of Chemistry of Great Britain and a Fellow of the Chemical Society of London . In 1908–1909, he worked with Fritz Haber in Germany on

3120-493: The fully developed pore structure, but have been oxidized again on the surface after manufacture and are therefore no longer pyrophoric . The reactivation of such pre-reduced catalysts requires only 30 to 40 hours instead of several days. In addition to the short start-up time, they have other advantages such as higher water resistance and lower weight. Many efforts have been made to improve the Haber–Bosch process. Many metals were tested as catalysts. The requirement for suitability

3185-401: The industrially used reaction temperature of 450 to 550 °C an optimum between the decomposition of ammonia into the starting materials and the effectiveness of the catalyst is achieved. The formed ammonia is continuously removed from the system. The volume fraction of ammonia in the gas mixture is about 20%. The inert components, especially the noble gases such as argon , should not exceed

3250-437: The method of rapid cooling is often employed. The reduction of the precursor magnetite to α-iron is carried out directly in the production plant with synthesis gas . The reduction of the magnetite proceeds via the formation of wüstite (FeO) so that particles with a core of magnetite become surrounded by a shell of wüstite. The further reduction of magnetite and wüstite leads to the formation of α-iron, which forms together with

3315-569: The method used. The resulting ammonia must then be separated from the residual hydrogen and nitrogen at temperatures of −20 °C (−4 °F). The Haber–Bosch process relies on catalysts to accelerate N 2 hydrogenation. The catalysts are heterogeneous solids that interact with gaseous reagents. The catalyst typically consists of finely divided iron bound to an iron oxide carrier containing promoters possibly including aluminium oxide , potassium oxide , calcium oxide , potassium hydroxide, molybdenum, and magnesium oxide . The iron catalyst

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3380-520: The original Haber process (20 MPa (200 bar; 2,900 psi) and 500 °C (932 °F)), albeit with improved single-pass conversion and lower energy consumption due to process and catalyst optimization. Combined with the energy needed to produce hydrogen and purified atmospheric nitrogen, ammonia production is energy-intensive, accounting for 1% to 2% of global energy consumption , 3% of global carbon emissions , and 3% to 5% of natural gas consumption. Hydrogen required for ammonia synthesis

3445-737: The outbreak of the first World War, but was released to work for the Auergesellschaft during the war. He returned to the UK after the war. He joined the General Electric Company (UK) research laboratory, where he remained for the rest of his career, working on thermionic valves . He lived in Penn, Buckinghamshire and was a noted philanthropist using the royalty income he received from the Haber patent. His two sons were both killed during World War II . This article about

3510-469: The promoters the outer shell. The involved processes are complex and depend on the reduction temperature: At lower temperatures, wüstite disproportionates into an iron phase and a magnetite phase; at higher temperatures, the reduction of the wüstite and magnetite to iron dominates. The α-iron forms primary crystallites with a diameter of about 30 nanometers. These crystallites form a bimodal pore system with pore diameters of about 10 nanometers (produced by

3575-438: The reaction is exothermic , the equilibrium of the reaction shifts at lower temperatures to the ammonia side. Furthermore, four volumetric units of the raw materials produce two volumetric units of ammonia. According to Le Chatelier's principle , higher pressure favours ammonia. High pressure is necessary to ensure sufficient surface coverage of the catalyst with nitrogen. For this reason, a ratio of nitrogen to hydrogen of 1 to 3,

3640-402: The reduction of the magnetite phase) and of 25 to 50 nanometers (produced by the reduction of the wüstite phase). With the exception of cobalt oxide , the promoters are not reduced. During the reduction of the iron oxide with synthesis gas, water vapor is formed. This water vapor must be considered for high catalyst quality as contact with the finely divided iron would lead to premature aging of

3705-591: The right of the iron group, in contrast, adsorb nitrogen too weakly for ammonia synthesis. Haber initially used catalysts based on osmium and uranium . Uranium reacts to its nitride during catalysis, while osmium oxide is rare. According to theoretical and practical studies, improvements over pure iron are limited. The activity of iron catalysts is increased by the inclusion of cobalt. Ruthenium forms highly active catalysts. Allowing milder operating pressures and temperatures, Ru-based materials are referred to as second-generation catalysts. Such catalysts are prepared by

3770-659: The salt most generally used being the chloride ( sal-ammoniac ). Adolph Frank and Nikodem Caro found that Nitrogen could be fixed by using the same calcium carbide produced to make acetylene to form calcium-cyanamide, which could then be divided with water to form ammonia. The method was developed between 1895 and 1899. While not strictly speaking a method of producing ammonia, nitrogen can be fixed by passing it (with oxygen) through an electric spark. Heating metals such as magnesium in an atmosphere of pure nitrogen produces nitride , which when combined with water produce metal hydroxide and ammonia. The Haber process , also called

3835-420: The set-up of a modern (designed in the early 1960s by Kellogg ) "single-train" Haber–Bosch plant: Ammonia production Before the start of World War I , most ammonia was obtained by the dry distillation of nitrogenous vegetable and animal products; by the reduction of nitrous acid and nitrites with hydrogen ; and also by the decomposition of ammonium salts by alkaline hydroxides or by quicklime ,

3900-402: The steps are as follows; The hydrogen is catalytically reacted with nitrogen (derived from process air) to form anhydrous liquid ammonia . It is difficult and expensive, as lower temperatures result in slower reaction kinetics (hence a slower reaction rate ) and high pressure requires high-strength pressure vessels that resist hydrogen embrittlement . Diatomic nitrogen is bound together by

3965-427: The synthesis gas mixture such as noble gases or methane are not strictly poisons, they accumulate through the recycling of the process gases and thus lower the partial pressure of the reactants, which in turn slows conversion. The reaction is: The reaction is an exothermic equilibrium reaction in which the gas volume is reduced. The equilibrium constant K eq of the reaction (see table) and obtained from: Since

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4030-428: The temperature is too high; instead it is removed from the gases leaving the reaction vessel. The hot gases are cooled under high pressure, allowing the ammonia to condense and be removed as a liquid. Unreacted hydrogen and nitrogen gases are returned to the reaction vessel for another round. While most ammonia is removed (typically down to 2–5 mol.%), some ammonia remains in the recycle stream. In academic literature,

4095-537: The undesirable effect of binding ammonia to the surface. Catalyst poisons lower catalyst activity. They are usually impurities in the synthesis gas . Permanent poisons cause irreversible loss of catalytic activity, while temporary poisons lower the activity while present. Sulfur compounds, phosphorus compounds, arsenic compounds, and chlorine compounds are permanent poisons. Oxygenic compounds like water, carbon monoxide , carbon dioxide , and oxygen are temporary poisons. Although chemically inert components of

4160-515: Was also controlled by the British. Moreover, even if German commercial interests had nominal legal control of such resources, the Allies controlled the sea lanes and imposed a highly effective blockade which would have prevented such supplies from reaching Germany. The Haber process proved so essential to the German war effort that it is considered virtually certain Germany would have been defeated in

4225-461: Was produced from the Hydro plant at Vemork . Other possibilities include biological hydrogen production or photolysis , but at present, steam reforming of natural gas is the most economical means of mass-producing hydrogen. The choice of catalyst is important for synthesizing ammonia. In 2012, Hideo Hosono 's group found that Ru -loaded calcium-aluminum oxide C12A7: e electride works well as

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