|This article has been reviewed by Nature on December 14 2005.
Comments: It was found to have 2 inaccuracies.
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|Haber process has been listed as a level-4 vital article in Science. If you can improve it, please do. This article has been rated as B-Class.|
|WikiProject Chemistry||(Rated B-class, High-importance)|
- 1 syngas preparation
- 2 Errors ID'd by Nature, to correct
- 3 1% of the world's energy supply …
- 4 I've added
- 5 pressure
- 6 catalyst
- 7 Rewrite
- 8 Source materials
- 9 Equilibrium Constants Error
- 10 Rewrite needed
- 11 Economic effects?
- 12 "Synthesis gas preparation" makes no sense to a non-chemist
- 13 Where does the C go
- 14 what actually is the Haber Process?
- 15 Haber process not really Fritz Haber's
- 16 ΔH° changed to just ΔH
- 17 environmental consequences
- 18 History section
- 19 Source needed for the statistic "3-5% of world natural gas production is used in fertilizer production"
- 20 Refimprove template
- 21 "ranging from 6–18 MPa"
- 22 Haber-Bosch
- 23 Preparing the catalyst
- 24 File:Haber-Bosch-En.svg
I have serious doubts on the preparation of syngas, the use of ZnO as a desulfurization reagent is obsolete, as is the CO2 separation by K2CO3. maybe this was the original process, no? CO2 is nowadays removed by pressure swing adsorption, and desulphurization is also performed more modernly... Sikkema (talk) 09:39, 11 June 2008 (UTC)
Errors ID'd by Nature, to correct
The results of what exactly Nature suggested should be corrected is out... italicize each bullet point once you make the correction. -- user:zanimum
- The statement "The process was developed by Fritz Haber and Carl Bosch in 1909 and patented in 1910." is slightly misleading. There are early patents, one in 1908 by Haber meant to protect his process, which was discovered independent of Bosch by Haber and his co-workers, one of whom was Le Rossignol. To be honest, the word "developed" does cover this aspect since it was Haber who "discovered" the process while it was Bosch as BASF who made it industrially viable.
- In the last sentence, 'about half' is vague enough to be misleading.
- The article needs an historical approach and a table Tamperature x Keq must be created.
1% of the world's energy supply …
"1% of the world's energy supply is consumed in the manufacturing of that fertilizer (Science 297(1654), Sep 2002)."
I'm assuming this should be "1% of the world's annual energy consumption …"? --Andymussell 03:03, 8 October 2006 (UTC)
Well Ammonia is a very useful chemical so it makes sense it takes a lot to make. LoyalSoldier 05:56, 28 March 2007 (UTC)
I've added related links because the amonium production process is very linked to these articles
I hope ya like it
regards -- User:richardba 02:30, 11 October 2006 (UTC)
by increassing pressure will also incress the reactian products? but has weakness can be overcome by?
I understand the catalyst is very important to this reaction; without it the reaction would be too slow to be commercially viable. Could someone go into greater detail on that?
- Can you say more clearly what exactly you mean? The article has mentioned fully all the needed catalysts and promoters. Causesobad → (Talk) 16:32, 15 February 2007 (UTC)
I have rewritten the whole article, expanding it, and providing more detail on the reactions that take place. I used most of the previous information anyway, after just moving it around. A.Tomberg 20:52, 21 April 2007 (UTC)
I gave different estimates exactly because wasn't sure of the exact values. So could someone please find a reliable source and give those values with a reference. I hope that would solve the problem. --22.214.171.124 21:34, 5 June 2007 (UTC)
The pressure varies from one plant to another.
Where is the hydrogen used usually sourced from? 126.96.36.199 12:26, 12 June 2007 (UTC)
Now the article says it is produced from natural gas (which is true for 95% of the hydrogen production in the world), but it should not cover how hydrogen is produced in detail, since the hydrogen production is not considered a part of the Haber process, and also is covered elsewhere.
Equilibrium Constants Error
There is an error in the table of equilibrium constants. They do NOT obey van't Hoff (try plotting ln(K) vs 1/T to test it yourself). I suspect the 25C was meant to be 100C, as that would look a lot better. BUT, I don't have a reliable source for these constants to hand, so I cannot correct this now, I hope one of you can. 99of9 07:37, 13 September 2007 (UTC)
In addition, Le Chatelier's principle does not apply to heat as a product or reactant for exothermic and endothermic reactions, respectively. Increasing the temperature simply shifts the equilibrium constant closer to 1 as K = exp(-delta G/RT). In other words, you cannot use heat to force the reaction backwards or forwards past K = 1, so this is not an application of Le Chatelier's principle. Lcscipiop (talk) 17:53, 12 December 2009 (UTC)
This article is a bit of a mess - loads of information but repetitive, occasionally confusing, too chatty and informal - reads a bit like an A-level essay when it comes to describing the effects on equilibria and reaction rates. The introductory paragraph is especially weak:
1. The Haber Process is not the reaction between nitorgen and hydrogen but it is the whole industrial set-up required to make that reaction happen in a viable manner; 2. "The Haber process is important because ammonia is difficult to produce, on an industrial scale". Er ... except by the Haber process... one might make the same claim for any industrial process. 3. "Even though 78.1% of the air we breathe is nitrogen, the gas is relatively inert due to the strength of the triple bond that keeps the molecule together." Atmospheric abundance is only tenuously related to the character of the N-N bond; "keeps the molecule together" - what is this? marriage guidance or what??? 4. "It was not until the start of the twentieth century that this method was developed ... " Is this an implied criticism of human slackness in not coming up with this sooner... 5. "which can then be oxidised to make the nitrates and nitrites essential for the production of nitrate fertilizer and munitions." Or not.
And that's just paragraph 1. Unless I get flamed I might edit some of this in future... Galatian 12:50, 4 October 2007 (UTC)
- I'd say go right ahead. I agree with all of your criticisms. 99of9 13:51, 4 October 2007 (UTC)
Shouldn't this section touch on the historical effects the HP had on Chile? From what I understand (http://en.wikipedia.org/wiki/War_of_the_Pacific#Long-term_consequences) they were severe. —Preceding unsigned comment added by Doctor Optimal (talk • contribs) 20:08, 22 October 2007 (UTC)
- absolutely so, its global impact was huge, the Haber process killed millions of people as a consequence of explosives and it saved millions of people as a consequence of fertilizers V8rik 20:51, 22 October 2007 (UTC)
- I don't know how many it killed, but I'd say it saved billions, in a way (of course, if there were no Haber process the world population might not have increased so much and billions of them might not have been born, but who knows?). --Itub 06:25, 23 October 2007 (UTC)
- I already added the effects in Chilean Economy.
"Synthesis gas preparation" makes no sense to a non-chemist
The inputs are (apparently) methane, air, H2O, CO, and K2CO3
The steps seem to go back and forth between CO2, H2O, and H2.
If I understand it correctly:
"Steam reforming" converts CH4 + H2O to H2 + CO2. It says there are two steps, identifies one step, but not the second step. Or is "Secondary reforming" the second step?
In "Secondary reforming", the mixture is combined with air (N2 and O2). Some of the H2 combines with the O2 to make H2O, leaving N2.
In the "two shifts", CO is added to the mixture; it takes the O from H2O, recovering the H2. (Where does the CO come from?)
The CO2 removal seems pretty straightforward.
The "Methanator" is a little obscure: how is the methane "recycled", and what becomes of the H2O generated?
I see that the bold-face numbers at the right are the N2:H2 ratios at each stage.
If this could all be stated in lay-acceptable language, it would be much easier to understand.
- It is not only to non-chemist, as a chemistry student it doesn't make sense to me either. I will try to correct it.
The second reaction from the steam reforming step is simply the shift reaction which doesn't happen untill later in the process, so that is wrong.
The reaction given for secondary reforming is a side reaction and not the reason why secondary reforming is done, I have added the correct reactions and a small explanation
- I'm not a chemistry student, but the bit about turning carbon dioxide back into methane was very obviously wrong. So I consulted a good friend of mine, who is a professional chemist, and he looked up that bit in "Chemistry of the Elements" and reported that it was carbon *monoxide* that got recycled, not dioxide. He didn't want to fix it, so I tried. I don't claim my edits make the article good, as it's out of my area of expertise, however, it is certainly much better now. Obscuranym (talk) 02:54, 22 February 2009 (UTC)
Where does the C go
Sorry if this doesn't reflect deep thought, or recent schooling.
The article seems to say (at the highest level) that CH4 + H2O + N2 + O2 => NH4.
Aren't we missing a few C's and O's on the output?
My misunderstanding centers on the sentence "The gas mixture is now passed into a methanator which converts any remaining CO2 into methane."
To my confused eyes, that would seem to convert exactly all of the desired output (H2) plus the undesirable CO2 back into CH4, which was the original input.
I would like to see the article directly address what comes out of this process. Where does the C end up? Not as endlessly recycled CH4, I guess.
Of course if this is an idiotic question, remove it.
- It is a good question. The presentation in this article is not clear and it skips some steps. According to Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419., the CO2 is removed by "scrubbing" with a base such as potassium carbonate, and then, the remaining traces of CO (not CO2!) are hydrogenated to methane in the methanation step. While this hydrogenation is indeed the opposite of the first step in the process, it is necessary because the CO would poison the catalyst that is used for the ammonia synthesis step, and since only traces of CO remain at this point, it is not too much of a waste. Now, regarding the question of what happens to the carbon: the base that was used for the scrubbing is regenerating by heating, which releases CO2. I don't know if this just goes to the atmosphere or if it is economical to store the CO2 and sell it. But you are right, the CO2 has to go somewhere! --Itub (talk) 09:46, 23 June 2008 (UTC)
what actually is the Haber Process?
This source says nothing about the production of hydrogen from natural gas being part of the process, whereas the article implied that it was, so I have amended the article accordingly - hope that is right?Engineman (talk) 04:38, 24 July 2008 (UTC)
From Dirac Delta Science and engineering encyclopedia http://www.diracdelta.co.uk/science/source/h/a/haber%20process/source.html
"The Haber process, named after Fritz Haber, is an industrial process in which ammonia is manufactured by direct combination of its elements, nitrogen and hydrogen. The reaction is carried out at 400 to 500°C and at 200 atmospheres. The two gases (nitrogen and hydrogen), in the proportions of 1:3 by volume, are passed over a catalyst of finely divided iron. Around 10% of the reactants combine, and the unused gases are recycled. The ammonia is separated by either dissolving in water or cooling to liquid form".
- I'm not sure--the books I've seen that talk about it in detail seem to refer to the entire process as the Haber-Bosch process. There is generally a difference between a "process" (multi-step) and a single reaction, which is just one step. I suspect that a process that used H2 from electrolysis would have a different name, probably including Haber but also the other author (but I have to check). --Itub (talk) 05:33, 24 July 2008 (UTC)
Haber process not really Fritz Haber's
In the book A Most Damnable Invention by Stephen Bown it says that nitrogen fixation was already known in the 1850's by other scientists and that the only thing that Fritz Haber had contributed to the process was the catalyst which was replaced with a different catalyst by Carl Bosch for the industrial production. So should Fritz Haber really deserve that much credit?
- Even if the chemical reaction itself was known for decades, being able to carry it out in a practical way was a major achievement of chemical engineering. It required the development of novel high-pressure reactors and extensive research in catalysis and chemical thermodynamics, fields which were relatively new at the time. That's why it was recognized with two Nobel Prizes. One went to Haber, and one to Bosch. Many call this the Haber-Bosch process, which is probably more fair. (Of course, there's also the usual politics when assigning credit and all that...) --Itub (talk) 20:19, 23 December 2008 (UTC)
ΔH° changed to just ΔH
I believe the degree symbol means that the reaction is done under standard conditions - 1 atmosphere of pressure, and at either 0°C or 25°C depending on who you ask - and the Haber process is naturally not at these conditions. If the degree symbol means something elsewhere, feel free to revert. UltimateLurker (talk) 19:01, 18 March 2009 (UTC)
There is little mention of the environmental consequences of the Haber-Bosch process in this article. the only mention is
- "That fertilizer is responsible for sustaining one-third of the Earth's population, as well as various deleterious environmental consequences."
here are a few of the deleterious environmental consequences of synthetic nitrogen
- nitrogenous runoff causing harmful algal blooms and "dead zones"
- contamination of drinking water reserves resulting in a wide variety of severe health effects
- increase atmospheric levels of the greeenhouse gas nitrous oxide.
- formation of smog
- acid rain —Preceding unsigned comment added by 188.8.131.52 (talk) 18:28, 22 June 2009 (UTC)
Was the ammonia first converted to potassium nitrate and later converted to other chemicals in WW I? What I know is that you go directly to burn ammonia with air and react it with water to form nitric acid. Most of the expolsives in WWI were already organic nitrate compounds not inorganic nitric mixtures like black powder. --Stone (talk) 12:56, 29 December 2010 (UTC)
Source needed for the statistic "3-5% of world natural gas production is used in fertilizer production"
Would someone find that statistic again? It seems to be missing from all the citations in both the Fertilizer and Haber process articles. And find it in something that's not hidden behind a paywall. No one's going to look in Science to find a simple stat that should be available freely on a government or industry website. —Preceding unsigned comment added by 184.108.40.206 (talk) 23:44, 24 April 2011 (UTC)
I added the refimprove template to this page because there are few sources on some of the most important sections. The following is an example: The final stage, which is the actual Haber process, is the synthesis of ammonia using an iron catalyst promoted with K2O, CaO and Al2O3:
- N2 (g) + 3 H2 (g) ⇌ 2 NH3 (g) (ΔH = −92.22 kJ·mol−1)
This is done at 15–25 MPa (150–250 bar) and between 300 and 550 °C, as the gases are passed over four beds of catalyst, with cooling between each pass so as to maintain a reasonable equilibrium constant. On each pass only about 15% conversion occurs, but any unreacted gases are recycled, and eventually an overall conversion of 97% is achieved.
The steam reforming, shift conversion, carbon dioxide removal, and methanation steps each operate at absolute pressures of about 2.5–3.5 MPa (25–35 bar), and the ammonia synthesis loop operates at absolute pressures ranging from 6–18 MPa (59–178 atm), depending upon which proprietary design is used.
I don't know where to find sources, but if anyone does, please help improve the page. 220.127.116.11 (talk) 15:10, 26 April 2012 (UTC) Woops. I wasn't logged in there. rdm_box 15:11, 26 April 2012 (UTC) — Preceding unsigned comment added by Rdmbox (talk • contribs)
"ranging from 6–18 MPa"
Given Carl Bosch's equally-important participation in creating the process, it seems like a glaring mistake to leave his name out of it. — Preceding unsigned comment added by 18.104.22.168 (talk) 06:19, 3 November 2012 (UTC)
- Thank you for your comment. The article states "... also called the Haber–Bosch process ...", and Haber–Bosch process redirects to this article. Are there some other specific changes you would suggest? – Wdchk (talk) 15:52, 3 November 2012 (UTC)
Preparing the catalyst
The article currently contains: "In industrial practice, the iron catalyst is prepared by exposing a mass of magnetite, an iron oxide, to the hot hydrogen feedstock".
I seem to recall hearing that, in order to ensure sufficient purity, a synthetic form of iron oxide is used: jeweller's rouge, for this purpose prepared in situ within the catalyst bed itself by destructively distilling ferrous oxalate that has itself been obtained in a pure form by the double decomposition of pure solutions of ferrous chloride and sodium oxalate. However, a quick glance at the relevant articles suggests that ferrous oxalate could be worse for this purpose than ferric hydroxide as ferrous oxalate produces finely divided iron as well as iron oxide(s), so possibly I am misremembering or possibly the iron produced just doesn't matter. Can anyone provide accurate details and citations for all this and update the article accordingly? PMLawrence (talk) 13:46, 7 September 2014 (UTC)
- Ullmann's Encyclopedia does not mention oxalate or rouge. The section on catalyst preparation was expanded somewhat. --Smokefoot (talk) 15:04, 7 September 2014 (UTC)