Talk:Pyrolysis

Uncategorized

(added in retrospect)--Tunheim 19:10, 3 February 2007 (UTC)

--Alex 08:31, 17 July 2006 (UTC)

Section on Bio-oil?

I still think that there should be a section on bio-oil: 1) There are 4 sections on solid products of pyrolysis: charcoal, biochar, coke and carbon fiber. There is only 1 section on biofule that looks at liquid products. This is unbalanced. 2) The current section on biofuel ignores the real difficulties encountered when using bio-oil as a fuel. 3) Although some companies, recently, have used bio-oil as a biofuel, the companies that have been in business for more than 10 years produce bio-oil for non-fuel applications (Ensyn and RTI, for example). It would better to replace the "bio-fuel" title by "bio-oil" and, then, talk about fuel and other applications. Cbriens (talk) 05:55, 12 January 2009 (UTC)

Anhydrous pyrolysis

I slightly modified the first sentence of the Anhydrous Pyrolysis section to make it compatible with the rest of the article, i.e. the presence of a section on Hydrous Pyrolysis.--Cbriens 17:06, 27 October 2007 (UTC)

Waste pyrolysis

This page needs a subsection on Waste pyrolysis plants which are being globally proposed as alternative waste treatment solutions.--Alex 11:48, 25 July 2006 (UTC)

• i've shifted things around a bit, there is a new section which includes waste as an industrial source David Woodward 08:01, 28 October 2007 (UTC)

Range of temperatures

It says: "Pyrolysis typically occurs under pressure and at operating temperatures above 430°C (800°F)." This phrase applies only to *some* process of *industrial* pyrolysis, which should be specified (perhaps pyrolysis of wood scraps and sawdust to generate charcoal+?). Pyrolysis is a general term and it can occur anywhere (nature, kitchen, lab, etc.), to any (organic?) substance, at temperatures as low as 100°C. Jorge Stolfi 01:43, 11 Mar 2004 (UTC)

Jorge Stolfi, could you possibly read this pictoral backgrounder I wrote, and tell me or just fix anything you find wrong with it? I am using it in an RfC, and would like someone else to check it if possible. Fifteen years later, this pyrolysis article is still rather focussed on oil chemistry; if you have time to broaden it, I'd also really appreciate that. I've added a picture of charcoal. HLHJ (talk) 01:34, 23 February 2019 (UTC)

HLHJ, thanks for that diagram and text! I have added the diagram to this article, and adapted your text on stages of pyrolysis to the new section "General processes and mechanisms". The rest of your text and the picture gallery seem more appropriate for other articles, such as charcoal.
If you are willing to improve that diagram, may I suggest that you trim down the text labels to the bare minimum. Namely, I think that these texts would be enough:

Oxidation//Carbon combines with O2 yielding CO and CO2

Pyrolysis//Organic molecules break down, volatile products escape

Dehydration//Little chemical change, water and volatiles escape

water//freezes  •  water//boils  •  carbon//ignites

Charring (Carbonization)//Formation of brown-black char

Most of the information in the current text labels should be (and already is) in the text of the article.
Also, I would put the four bands in the order of increasing temperature from top to bottom: that is, Dehydration, Pyrolysis, Charring, and Oxidation -- all four above the temperature scale--Jorge Stolfi (talk) 01:19, 3 March 2019 (UTC)

Firefighting

Why is this article in the firefighting category? --Andrew 20:04, Feb 7, 2005 (UTC)

You’re absolutely right 212.102.225.147 11:06, 23 Jun 2005 (UTC)

I believe you mean "Yes, that was an error". Thanks for fixing the categories. (SEWilco 14:36, 23 Jun 2005 (UTC))

Yep... you’re also right. Weird, two agreeings on such a little talk page. 212.102.225.147 29 June 2005 06:51 (UTC)

I can see how it makes sense. A lot of the knowledge on how to best pyrolyse materials has actually been invented by the people that work with preventing it. In firefighting, or more specifically when making fire-dampening (what is the right term here) materials, you wanna avoid too much pyrolysis. So pyrolysis is a very important reaction to long-term firefighting, just like uv-induced high-altitude detoriation might be an issue for the flight industry. Even though the day to day people might not be thinking to much about it (firefighters / pilots, depending on the example). --Alf 17:05, 27 July 2006 (UTC)

Added Pyrolysis#Fire protection. Makes sense now? --Tunheim 11:48, 21 March 2007 (UTC)

some discussion recently in New Scientist about unburnt pyrolysis products: http://environment.newscientist.com/channel/earth/mg19526151.900-ignition-impossible-when-wildfires-set-the-air-alight.html http://www.newscientist.com/article/mg19526200.600-burning-bush.html David Woodward 08:08, 28 October 2007 (UTC)

Term used more loosely?

I believe this term is sometimes used more loosely to mean "heating to decompose organic materials" (absense of O2 not specified). I know that this is not really correct, but I have see this in, for example, analytic glassware cleaning protocols. Can anyone confirm this looser definition? ike9898 22:27, 6 December 2005 (UTC)

The strictest definition is that contained in the very term pyrolysis: decomposition or dissolution (lysis) by intense heat or by fire (pyros, both from Greek). When it comes to organics, of course, the absence of O2 is in most cases a must so that oxidation or combustion are not the main reactions. So you are partially right.--Unconcerned 08:05, 7 December 2005 (UTC)

Hmm. I don't understand your meaning. If you are trying to eliminate surface contaminants, do you really care if those contaminants are oxidized or combusted? ike9898 14:43, 7 December 2005 (UTC)

Well, the term might be used in some cases as a fancy substitute for burning, but the chemical reaction/process of pyrolysis is fundamentally different from a combustion process in that the reactant molecules are fragmented without any incorporation of new atoms. It'd be nice though if you could include in the article the specific usage you say you're aware of.--Unconcerned 05:23, 8 December 2005 (UTC)

I'd say this is an example of mis-use of the word. Simple and easy :P --Tunheim 19:13, 3 February 2007 (UTC)

Merge?

There's three closely related articles on this general topic: This one, Destructive distillation and Cracking (chemistry). The cracking article is mostly concerned with petroleum, but the Pyrolysis and Destructive distillation have large overlaps. I think at least those two should be merged. Toiyabe 22:30, 22 February 2006 (UTC)

• all the keywords are all used in a different context, different application, you can see for yourself when you look at the what links here. These articles should not merge. V8rik 00:03, 23 February 2006 (UTC)

The "what links here" for Pyrolysis and Destructive Distillation look pretty similar in application and context to me. Can you explain what the difference between Pyrolysis and Destructive Distillation is? Toiyabe 01:22, 23 February 2006 (UTC)

pyrolysis in the laboratory is actually used in organic synthesis particularly radical chemistry and rearrangements. Destructive Distillation is an industrial process. V8rik 17:56, 23 February 2006 (UTC)

I am no chemist, but I would guess that "Destructive distillation" (DD) is generally used for industrial processes, and implies that the distilled phases are condensed and used; whereas pyrolysis is a geeneral chemical process, that may happen in any settings (including by accident) and does not imply recovery or use of the byproducts. So DD uses pyrolysis, but there is much pyrolysis that is not DD. Makes sense? Jorge Stolfi 12:51, 23 February 2006 (UTC)

OK, I can live with that. To be consistent, a lot of the links to pyrolysis should be moved to DD. DD and pyrolysis should include text that explains the distinction. Toiyabe 16:50, 23 February 2006 (UTC)

I have suggested that the stub "Dry distillation" be merged into this article because:

• Dry distillation is essentially the same as pyrolysis.
• This is much more of a complete article than is the stub suggested to be merged into this article.

I have tagged both this article and the stub with merge tags. - mbeychok 21:34, 7 May 2006 (UTC)

• • Dry distillation is not the same as pyrolysis. Dry distillation does not necessarily involve chemical decomposition. Destructive distillation is pyrolysis with collection of produced gases.

These should not be merged. According to the "dry distillation" entry, there is an intent to collect the byproducts from a reaction, so it is a process. Pyrolysis refers to general chemical thermal decomposition, with or without oxygen present, and the compound doesn't even have to be organic. Sometimes industrial or lab terminology hijacks a strict definition to make it into more of a process definition. If this is the case for a specific use of the term "pyrolysis", a link should be added to point to "dry distillation". 208.223.129.170 14:38, 1 June 2006 (UTC)

• Non-mergers win by a small but perceptible margin, merge notice removed..... V8rik 22:24, 12 August 2006 (UTC)

To me dry distillation and destructive distillation seems to be the same thing. It has been previously stated in the discussion thread of both articles that they are not the same thing (A B). However no explanation or references has been given to back up the statement. Would someone care to explain the difference? Please reply at destructive distillation talk page. --Alf 09:33, 22 December 2006 (UTC)

Pyrolysis with charcoal production and coke production?

I am not especially happy that the two industrial examples above are listed as examples of pyrolysis. Strictly speaking, they are not. Both involve partial combustion using air in order to generate the heat required for the pyrolysis. In both examples about 10% of the material is combusted, to pyrolyse the other 90%. I am not arguing that these processes don't contain pyrolysis, they do. But they are not examples of pyrolysis in its true sense, which must, by necessity involve indirect heating (to avoid contact with oxygen or toher reagents). What do you think?

I think they are important examples of pyrolysis being part of an industrial/chemical process. Just like an ion transfer or a reduction might be part of a more complex chemical process. As long as we make it clear that the pyrolysis is fueled by the heat from the combustion. So in my opinion it's a good example, but it might be possible to write it better. --Alf 09:42, 22 December 2006 (UTC)

I added other processes that do not use partial combustion--Cbriens 18:37, 2 January 2007 (UTC)

Link spam

Presently (http://en.wikipedia.org/w/index.php?title=Pyrolysis&oldid=105365069) there are multiple links in the article to companies working with pyrolysis technology. They are incorporated into the text. However, to me, it makes the article seem a little more like a buyers guide than an encyclopædic article. Any thoughts? Are there any Wikipedia policies, discussions or guidelines on this? Also, unless I receive any good reasons to keep these links, I'll probably remove them. --Tunheim 09:59, 6 February 2007 (UTC)

I agree. Remove them. No disrespect to the companies concerned, but they do not deserve special status amongst hundreds of others. The examples of particular company processes give detail but not depth or understanding to the article. Indeed, they tend to give a bias and a suggestion that this is something new.Chemical Engineer 21:49, 1 September 2007 (UTC)

• totally agree, i've just had a big session on this page and done some work on cleanup from this point of view. Relevant policy is WP:SOAP, specifically in these cases WP:NOT#ADVERTISING. I've changed some comm. links to alternative refs, burrowed down in comm. sites to link to more useful page rather than comm. front page, removed some paras all together (e.g. mobile fluidized bed). I have left some comm links in an external links section, since there is some relevance. Hopefully this has lifted the article standard. I think this is a particularly important article because of the potential for carbon seq. David Woodward 08:17, 28 October 2007 (UTC)

more to do

i'm wikied out at the moment, having left some jobs undone, i will probably be back, but here are some to-do's for anybody

• probably remove some detail about biochar, i don't want to lose material thought, so this might be transferred to biochar if it is not already duplicated there
• maybe too much info still in "4. Processes for biomass pyrolysis"? David Woodward 08:22, 28 October 2007 (UTC)

• Reference 14 doesn't exist anymore. Link does not work anymore. — Preceding unsigned comment added by Thvranken (talk • contribs) 15:48, 22 November 2012 (UTC)

Comment

This page should include a link to "Wood Gas" and to "Charcoal". The pyrolysis of wood produces a solid; the charcoal, and also gasses; the "wood gasses". These are all related concepts. I haven't figured out how to add links or I would do it myself. Alexander Selkirk Alexselkirk1704 (talk) 17:37, 12 April 2008 (UTC)

Microwaves should be mentioned as they are used for this. 80.186.110.204 (talk) 08:44, 3 July 2009 (UTC)

"bio-oil" redirect

I think this should be changed because of the product called Bio-Oil (TM) http://www.bio-oil-direct.co.uk/ Eugene-elgato (talk) 18:35, 8 February 2009 (UTC)

Agreed, I didn't expect to come here either 87.194.30.190 (talk) 21:47, 8 May 2009 (UTC)

In the research field, we call it either bio-oil of pyrolysis oil. Kind of like "Kleenex" has come to be the name of nose-tissues. If it really bothers you, go ahead and change all references to "bio-oil" to "pyrolysis-oil" (or "py-oil"). PyrolysisGenius (talk) 23:19, 25 June 2012 (UTC)

Carcinogens

Some mention of the carcinogens produced by the pyrolysis of food would be appropriate. 78.144.248.102 (talk) 10:42, 30 October 2009 (UTC)

This site mentions that heterocyclic amines and polycyclic aromatic hydrocarbons are known carcinogens produced when muscle meat is cooked at high temperatures. The site does not specify whether this is due to pyrolysis or some other process. http://www.cancer.gov/cancertopics/factsheet/Risk/cooked-meats The12thMan (talk) 21:41, 8 July 2011 (UTC)

Pyrolysis or non-organic materials

The article has been modified so as to imply that pyrolysis applies only to organic substances. However the term seems to be used also for inorganic substances, e.g. "Yakubovich and coworkers obtained insoluble polymers [...] by the pyrolysis of phosphazene phosphoxides at 220°C." [1]. So I will restore the original wording "mainly used for organics" (but not exclusively). All the best, --Jorge Stolfi (talk) 22:55, 4 January 2010 (UTC)

Same as Thermolysis?

The article states that pyrolysis is a special case of thermolysis. However, reading both articles, I could not find or imagine an example of thermolysis that is not a pyrolyis. In fact, the IUPAC Gold Book defines them as synonyms. http://goldbook.iupac.org/P04961.html and http://goldbook.iupac.org/T06326.html. Do you agree with that? 200.164.157.164 (talk) 19:21, 14 April 2010 (UTC)

Yes! The pages ought to be the same. However, thermolysis has colloquially come to be more broad (temperature-wise), including gasification and torrefaction as well. I don't know why, though. PyrolysisGenius (talk) 23:21, 25 June 2012 (UTC)

Pyrolysis is usually reported as a special case of thermolysis in review papers examining biomass as pyrolysis feedstock. I agree that coal for instance can be described as operated on by pyrolysis and thermolysis (with no difference at all?). If it is just a semantics issue, it'd be worth a note in the article about which scientific "cliques" use what term. I know torrefaction is usually considered a low temperature (200 celsius or less?) form of pyrolysis. Hero of Ludi (talk) 03:36, 17 August 2012 (UTC)

Chemistry and Biofuel sections edit

I expanded (actually rewrote) the Chemistry section to add more detail and improve the sense. I agreed with the original author, but just tried to add a little more detail from a personal survey of recent research. I neglected to add additional citations (I just left the original citation in place). I will add citations.

I also added a little more detail to the Biofuel section and linked out to biomass sources by name. I didn't add citations, but they could be added. Hero of Ludi (talk) 03:40, 17 August 2012 (UTC)

Laser cutting.

I believe (but don't have refs) that laser-cutting of wood produces it's effect by pyrolysis. If that's correct, it would be a useful addition to the Examples section. SteveBaker (talk) 20:10, 16 April 2013 (UTC)

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Energy claim

"Using tires as fuel produce equal energy as burning oil and 25% more energy than burning coal.[23]"

This statement is meaningless. Tabby (talk) 10:39, 1 August 2016 (UTC)

Edits of Jan 2018

Cooking

Today I removed this content. Unless one cooks like my grandmother, pyrolysis and the kitchen are not connected concepts. "Pyrolysis also plays an important role in several cooking procedures, such as baking, frying, grilling, and caramelizing.

Pyrolysis occurs whenever food is exposed to high enough temperatures in a dry environment, such as roasting, baking, toasting, or grilling. It is the chemical process responsible for the formation of the golden-brown crust in foods prepared by those methods.

In normal cooking, the main food components that undergo pyrolysis are carbohydrates (including sugars, starch, and fibre) and proteins. (See: Maillard reaction.) Pyrolysis of fats requires a much higher temperature, and, since it produces toxic and flammable products (such as acrolein), it is, in general, avoided in normal cooking. However, it may occur when one is grilling fatty meats over hot coals.

Even though cooking is normally carried out in air, the temperatures and environmental conditions are such that there is little or no combustion of the original substances or their decomposition products. In particular, the pyrolysis of proteins and carbohydrates begins at temperatures much lower than the ignition temperature of the solid residue, and the volatile subproducts are too diluted in air to ignite. (In flambé dishes, the flame is due mostly to combustion of the alcohol, while the crust is formed by pyrolysis as in baking.)

Pyrolysis of carbohydrates and proteins requires temperatures substantially higher than 100 °C (212 °F), so pyrolysis does not occur as long as free water is present, e.g., in boiling food — not even in a pressure cooker. When heated in the presence of water, carbohydrates and proteins suffer gradual hydrolysis rather than pyrolysis. For most foods, pyrolysis is usually confined to the outer layers of food, and begins only after those layers have dried out.

Food pyrolysis temperatures are, however, lower than the boiling point of lipids, so pyrolysis occurs when frying in vegetable oil or suet, or basting meat in its own fat.

Pyrolysis also plays an essential role in the production of barley tea, coffee, and roasted nuts such as peanuts and almonds. As these consist mostly of dry materials, the process of pyrolysis is not limited to the outermost layers but extends throughout the materials. In all these cases, pyrolysis creates or releases many of the substances that contribute to the flavor, color, and biological properties of the final product. It may also destroy some substances that are toxic, unpleasant in taste, or those that may contribute to spoilage.

Controlled pyrolysis of sugars starting at 170 °C (338 °F) produces caramel, a beige to brown water-soluble product widely used in confectionery and (in the form of caramel coloring) as a coloring agent for soft drinks and other industrialized food products.

Solid residue from the pyrolysis of spilled and splattered food creates the brown-black encrustation often seen on cooking vessels, stove tops, and the interior surfaces of ovens."--Smokefoot (talk) 01:29, 10 January 2018 (UTC)

• As you say, while many cooking processes never reach temperatures above 100 °C, many others -- like frying, roasting, grilling, baking etc. -- definitely go beyond the Mallard reaction and involve pyrolysis of proteins and other food components. So, what waas wrong with the removed line? Wrong section? The word "important"? --Jorge Stolfi (talk) 00:36, 3 March 2019 (UTC)

Biofuels angle

This WP:UNDUE ("hippie science") was also removed. The article is about pyrolysis, not someone's dream for how if might make the world wonderful..."[Pyrolysis of plastics produces fuels] with a higher cetane value and lower sulphur content than conventional diesel.<ref>[http://www.zerowaste.sa.gov.au/upload/resource-centre/publications/waste-to-energy/Case%20Study%203%20Cynar%20Plastics%20to%20Fuel%20FINAL.pdf Cynar Plastics to Diesel]. Ricardo – AEA Ltd (2013)</ref> Using pyrolysis to extract fuel from end-of-life plastic is a second-best option after recycling, is environmentally preferable to landfill, and can help reduce dependency on fossil fuels and geo-extraction."

Long essay on biochar, which is tangential to this topic. Reads like a rant. "Biochar improves the [[soil structure|soil texture]] and [[ecology]], increasing its ability to retain fertilizers and release them slowly. It naturally contains many of the [[micronutrient]]s needed by plants, such as [[selenium]]. Biochar is also safer than other "natural" fertilizers such as animal [[manure]], since it has been [[disinfect]]ed at high temperature. And, since it releases nutrients at a slow rate, it greatly reduces the risk of [[water table]] contamination.<ref name='gardaus1'> {{cite news | first = Peter | last = Cundall | title = Fact Sheet: Pete's Patch | date = 2007-10-27 | publisher = Australian Broadcasting Corporation | url = http://www.abc.net.au/gardening/stories/s2071694.htm | work = Gardening Australia | accessdate = 2008-07-10}}</ref> Biochar is also being considered for [[carbon dioxide sink|carbon sequestration]], with the aim of [[mitigation of global warming]].<ref name='horstman1'> {{cite news | first=Mark | last=Horstman | title=Agrichar – A solution to global warming? | date=2007-09-23 | publisher=Australian Broadcasting Corporation | url =http://www.abc.net.au/catalyst/stories/s2012892.htm | work =ABC TV Science: Catalyst | accessdate = 2008-07-10 }} </ref><ref> {{cite news |url=http://news.bbc.co.uk/1/hi/england/7993034.stm |title=Trial to reverse global warming |publisher=BBC News |accessdate=2009-04-21 | date=2009-04-09}} </ref><ref> {{cite news |url=http://www.economist.com/sciencetechnology/displaystory.cfm?story_id=14302001 |title=The virtues of biochar: A new growth industry? |date=2009-08-27 |publisher=The Economist |accessdate=2009-08-30 }} </ref> The solid, carbon-containing char produced can be sequestered in the ground, where it could remain for several hundred to a few thousand years.<ref>[http://www.biochar-international.org/biochar/faqs#q9 Frequently Asked Questions about Biochar | International Biochar Initiative]. Biochar-international.org (2013-04-19). Retrieved on 2013-06-01.</ref> Research continues about the processes responsible for long-term sequestration of carbon in soils.<ref>{{Cite journal|last=Schmidt|first=Michael W. I.|last2=Torn|first2=Margaret S.|last3=Abiven|first3=Samuel|last4=Dittmar|first4=Thorsten|last5=Guggenberger|first5=Georg|last6=Janssens|first6=Ivan A.|last7=Kleber|first7=Markus|last8=Kögel-Knabner|first8=Ingrid|last9=Lehmann|first9=Johannes|date=2011-10-06|title=Persistence of soil organic matter as an ecosystem property|url=http://www.nature.com/nature/journal/v478/n7367/abs/nature10386.html|journal=Nature|language=en|volume=478|issue=7367|pages=49–56|doi=10.1038/nature10386|issn=0028-0836|bibcode=2011Natur.478...49S}}</ref>"

--Smokefoot (talk) 14:38, 10 January 2018 (UTC)

Neanderthal's adhesives

"Neanderthals used pyrolysis of birch bark to produce a pitch with which they secured flaked stones to spear shafts.<ref>[https://www.pbs.org/wgbh/nova/evolution/defy-stereotypes.html NOVA – Official Website | Neanderthals Defy Stereotypes]. Pbs.org. Retrieved on 2016-12-16.</ref> Recently, researchers have developed a process to pyrolyze birch bark to produce an oil that can replace [[phenol]] in [[phenol formaldehyde resin]] (these resins are mostly used to manufacture [[plywood]]).<ref>Dongbing Li, Franco Berruti, Cedric Briens, "Autothermal fast pyrolysis of birch bark with partial oxidation in a fluidized bed reactor", Fuel, Volume 121, 1 April 2014, Pages 27–38</ref>" removed as tangential.--Smokefoot (talk) 14:48, 10 January 2018 (UTC)

Top graphic needs elaboration

I'm reasonably smart and sciencey and stuff but I have no idea what is going on in the graphic that is labeled "Simplified depiction of pyrolysis chemistry". I respectfully suggest it needs a really good descriptive caption or it should be eliminated.Kirkpete (talk) 23:32, 28 February 2019 (UTC)

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Wiki Education assignment: Environmental Chemistry

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