Product Code Database
Pyrolysis (; ) is a process involving the Bond cleavage in organic matter by thermal decomposition within an Chemically inert environment without oxygen.
The process is used heavily in the chemical industry, for example, to produce ethylene, many forms of carbon, and other chemicals from petroleum, coal, and even wood, or to produce coke from coal. It is used also in the conversion of natural gas (primarily methane) into hydrogen gas and solid carbon char, recently introduced on an industrial scale. Aspirational applications of pyrolysis would convert biomass into syngas and biochar, waste plastics back into usable oil, or waste into safely disposable substances.
Pyrolysis is different from gasification. In the chemical process industry, pyrolysis refers to a partial thermal degradation of carbonaceous materials that takes place in an Inert gas (oxygen free) atmosphere and produces both gases, liquids and solids. The pyrolysis can be extended to full gasification that produces mainly gaseous output, (2025). 9780470666883 ISBN 9780470666883 often with the addition of e.g. water steam to gasify residual carbonic solids, see Steam reforming.
Other pyrolysis types come from a different classification that focuses on the pyrolysis operating conditions and heating system used, which have an impact on the yield of the pyrolysis products.
| Slow low temperature pyrolysis (2025). 9780128045688 ISBN 9780128045688 | Temperature: 250-450 °C
Vapor residence time: 10-100 min Heating rate: 0.1-1 °C/s Feedstock size: 5-50 mm | Bio-oil ~30
Biochar~35 Gases~35 |
| Intermediate pyrolysis | Temperature: 600-800 °C
Vapor residence time: 0.5-20 s Heating rate: 1.0-10 °C/s Feedstock size: 1-5 mm | Bio-oil~50
Biochar~25 Gases~35 |
| Fast low temperature pyrolysis | Temperature: 250-450°C
Vapor residence time: 0.5-5 s Heating rate: 10-200 °C/s Feedstock size: <3 mm | Bio-oil ~50
Biochar~20 Gases~30 |
| Flash pyrolysis | Temperature: 800-1000 °C
Vapor residence time: <5 s Heating rate: >1000 °C/s Feedstock size: <0.2 mm | Bio-oil ~75
Biochar~12 Gases~13 |
| Hydro pyrolysis | Temperature: 350-600 °C
Vapor residence time: >15 s Heating rate: 10-300 °C/s | Not assigned |
| High temperature pyrolysis | Temperature: 800-1150 °C
Vapor residence time: 10-100 min
Heating rate: 0.1-1 °C/s | Bio-oil ~43
Biochar~22
Gases~45 |
The dry distillation of wood remained the major source of methanol into the early 20th century. Pyrolysis was instrumental in the discovery of many chemical substances, such as phosphorus from Microcosmic salt in concentrated urine, oxygen from mercuric oxide, and various .
In many settings, some amounts of oxygen, water, or other substances may be present, so that combustion, hydrolysis, or other chemical processes may occur besides pyrolysis proper. Sometimes those chemicals are added intentionally, as in the burning of firewood, in the traditional manufacture of charcoal, and in the steam cracking of crude oil.
Conversely, the starting material may be heated in a vacuum or in an inert atmosphere to avoid chemical side reactions (such as combustion or hydrolysis). Pyrolysis in a vacuum also lowers the boiling point of the byproducts, improving their recovery.
When organic matter is heated at increasing temperatures in open containers, the following processes generally occur, in successive or overlapping stages:
Inert gas purging is essential to manage inherent explosion risks. The procedure is not trivial and failure to keep oxygen out has led to accidents.
Pyrolysis of food can also be undesirable, as in the charring of burnt food (at temperatures too low for the oxidative combustion of carbon to produce flames and burn the food to ash).
Charcoal is a less smoky fuel than pyrolyzed wood. Some cities ban, or used to ban, wood fires; when residents only use charcoal (and similarly treated rock coal, called coke) air pollution is significantly reduced. In cities where people do not generally cook or heat with fires, this is not needed. In the mid-20th century, "smokeless" legislation in Europe required cleaner-burning techniques, such as coke fuel and smoke-burning incinerators as an effective measure to reduce air pollution
The coke-making or "coking" process consists of heating the material in "coking ovens" to very high temperatures (up to ) so that the molecules are broken down into lighter volatile substances, which leave the vessel, and a porous but hard residue that is mostly carbon and inorganic ash. The amount of volatiles varies with the source material, but is typically 25–30% of it by weight. High temperature pyrolysis is used on an industrial scale to convert coal into coke. This is useful in metallurgy, where the higher temperatures are necessary for many processes, such as steelmaking. Volatile by-products of this process are also often useful, including benzene and pyridine. Coke can also be produced from the solid residue left from petroleum refining.
The original xylem of the wood and the pores created by escaping gases combine to produce a light and porous material. By starting with a dense wood-like material, such as or peach endocarp, one obtains a form of charcoal with particularly fine pores (and hence a much larger pore surface area), called activated carbon, which is used as an adsorption for a wide range of chemical substances.
Biochar is the residue of incomplete organic pyrolysis, e.g., from cooking fires. It is a key component of the terra preta soils associated with ancient indigenous communities of the Amazon basin.
Pyrolysis is the reaction used to coat a preformed substrate with a layer of pyrolytic carbon. This is typically done in a fluidized bed reactor heated to . Pyrolytic carbon coatings are used in many applications, including artificial heart valves.Ratner, Buddy D. (2004). Pyrolytic carbon. In Biomaterials science: an introduction to materials in medicine . Academic Press. pp. 171–180. .
In the biomass components, the pyrolysis of hemicellulose happens between 210 and 310 °C. The pyrolysis of cellulose starts from 300 to 315 °C and ends at 360–380 °C, with a peak at 342–354 °C. Lignin starts to decompose at about 200 °C and continues until 1000 °C.
Synthetic diesel fuel by pyrolysis of organic materials is not yet economically competitive.
Syngas is usually produced by pyrolysis.
The low quality of oils produced through pyrolysis can be improved by physical and chemical processes, which might drive up production costs, but may make sense economically as circumstances change.
There is also the possibility of integrating with other processes such as mechanical biological treatment and anaerobic digestion.Marshall, A. T. & Morris, J. M. (2006) A Watery Solution and Sustainable Energy Parks , CIWM Journal, pp. 22–23 Fast pyrolysis is also investigated for biomass conversion.
gas turbine electric power generation, and hydrogen for industrial processes including producing ammonia fertilizer and cement.
Methane pyrolysis is the process operating around 1065 °C for producing hydrogen from natural gas that allows removal of carbon easily (solid carbon is a byproduct of the process).
The industrial quality solid carbon can then be sold or landfilled and is not released into the atmosphere, avoiding emission of greenhouse gas (GHG) or ground water pollution from a landfill.
In 2015, a company called Monolith Materials built a pilot plant in Redwood City, CA to study scaling Methane Pyrolysis using renewable power in the process. A successful pilot project then led to a larger commercial-scale demonstration plant in Hallam, Nebraska in 2016. As of 2020, this plant is operational and can produce around 14 metric tons of hydrogen per day. In 2021, the US Department of Energy backed Monolith Materials' plans for major expansion with a $1B loan guarantee. The funding will help produce a plant capable of generating 164 metric tons of hydrogen per day by 2024. Pilots with gas utilities and biogas plants are underway with companies like Modern Hydrogen. Volume production is also being evaluated in the BASF "methane pyrolysis at scale" pilot plant, the chemical engineering team at University of California - Santa Barbara and in such research laboratories as Karlsruhe Liquid-metal Laboratory (KALLA).
The Australian company Hazer Group was founded in 2010 to commercialise technology originally developed at the University of Western Australia. The company was listed on the ASX in December 2015. It is completing a commercial demonstration project to produce renewable hydrogen and graphite from wastewater and iron ore as a process catalyst use technology created by the University of Western Australia (UWA). The Commercial Demonstration Plant project is an Australian first, and expected to produce around 100 tonnes of fuel-grade hydrogen and 380 tonnes of graphite each year starting in 2023. It was scheduled to commence in 2022. "10 December 2021: Hazer Group (ASX: HZR) regret to advise that there has been a delay to the completion of the fabrication of the reactor for the Hazer Commercial Demonstration Project (CDP). This is expected to delay the planned commissioning of the Hazer CDP, with commissioning now expected to occur after our current target date of 1Q 2022." The Hazer Group has collaboration agreements with Engie for a facility in France in May 2023, A Memorandum of Understanding with Chubu Electric & Chiyoda in Japan April 2023 and an agreement with Suncor Energy and FortisBC to develop 2,500 tonnes per Annum Burrard-Hazer Hydrogen Production Plant in Canada April 2022
The American company C-Zero's technology converts natural gas into hydrogen and solid carbon. The hydrogen provides clean, low-cost energy on demand, while the carbon can be permanently sequestered. C-Zero announced in June 2022 that it closed a $34 million financing round led by SK Gas, a subsidiary of South Korea's second-largest conglomerate, the SK Group. SK Gas was joined by two other new investors, Engie New Ventures and Trafigura, one of the world's largest physical commodities trading companies, in addition to participation from existing investors including Breakthrough Energy Ventures, Eni Next, Mitsubishi Heavy Industries, and AP Ventures. Funding was for C-Zero's first pilot plant, which was expected to be online in Q1 2023. The plant may be capable of producing up to 400 kg of hydrogen per day from natural gas with no CO2 emissions.
One of the world's largest chemical companies, BASF, has been researching hydrogen pyrolysis for more than 10 years.
In tire waste management, tire pyrolysis is a well-developed technology.ผศ.ดร.ศิริรัตน์ จิตการค้า, "ไพโรไลซิสยางรถยนต์หมดสภาพ : กลไกการผลิตน้ำมันเชื้อเพลิงคุณภาพสูง"วิทยาลัยปิโตรเลียมและปิโตรเคมี จุฬาลงกรณ์มหาวิทยาลัย (in Thai) Jidgarnka, S. "Pyrolysis of Expired Car Tires: Mechanics of Producing High Quality Fuels" . Chulalongkorn University Department of Petrochemistry Other products from car tire pyrolysis include steel wires, carbon black and bitumen. The area faces legislative, economic, and marketing obstacles. Oil derived from tire rubber pyrolysis has a high sulfur content, which gives it high potential as a pollutant; consequently it should be desulfurized.
Alkaline pyrolysis of sewage sludge at low temperature of 500 °C can enhance production with in-situ carbon capture. The use of NaOH (sodium hydroxide) has the potential to produce -rich gas that can be used for fuels cells directly.
In early November 2021, the U.S. State of Georgia announced a joint effort with Igneo Technologies to build an $85 million large electronics recycling plant in the Port of Savannah. The project will focus on lower-value, plastics-heavy devices in the waste stream using multiple shredders and furnaces using pyrolysis technology.
Waste from pyrolysis itself can also be used for useful products. For example, contaminant-rich retentate from liquid-fed pyrolysis of postconsumer multilayer packaging waste can be used as novel building composite materials, which have higher compression strengths (10-12 MPa) than construction bricks and brickworks (7 MPa), as well as 57% lower density, 0.77 g/cm3 .
Two different types of experiments were conducted: one-stepwise pyrolysis and two-stepwise pyrolysis. One-stepwise pyrolysis consisted of a constant heating rate (10 °C min−1) from 30 to 720 °C. In the second step of the two-stepwise pyrolysis test the pyrolysates from the one-stepwise pyrolysis were pyrolyzed in the second heating zone which was controlled isothermally at 650 °C. The two-stepwise pyrolysis was used to focus primarily on how well affects carbon redistribution when adding heat through the second heating zone.
First noted was the thermolytic behaviors of TLW and TSW in both the and environments. For both TLW and TSW the thermolytic behaviors were identical at less than or equal to 660 °C in the and environments. The differences between the environments start to occur when temperatures increase above 660 °C and the residual mass percentages significantly decrease in the environment compared to that in the environment. This observation is likely due to the Boudouard reaction, where we see spontaneous gasification happening when temperatures exceed 710 °C. Although these observations were seen at temperatures lower than 710 °C it is most likely due to the catalytic capabilities of inorganics in TLW. It was further investigated by doing ICP-OES measurements and found that a fifth of the residual mass percentage was Ca species. is used in cigarette papers and filter material, leading to the explanation that degradation of causes pure reacting with Calcium oxide in a dynamic equilibrium state. This being the reason for seeing mass decay between 660 °C and 710 °C. Differences in differential thermogram (DTG) peaks for TLW were compared to TSW. TLW had four distinctive peaks at 87, 195, 265, and 306 °C whereas TSW had two major drop offs at 200 and 306 °C with one spike in between. The four peaks indicated that TLW contains more diverse types of additives than TSW. The residual mass percentage between TLW and TSW was further compared, where the residual mass in TSW was less than that of TLW for both and environments concluding that TSW has higher quantities of additives than TLW.
The one-stepwise pyrolysis experiment showed different results for the and environments. During this process the evolution of 5 different notable gases were observed. Hydrogen, Methane, Ethane, Carbon Dioxide, and Ethylene all are produced when the thermolytic rate of TLW began to be retarded at greater than or equal to 500 °C. Thermolytic rate begins at the same temperatures for both the and environment but there is higher concentration of the production of Hydrogen, Ethane, Ethylene, and Methane in the environment than that in the environment. The concentration of CO in the environment is significantly greater as temperatures increase past 600 °C and this is due to being liberated from in TLW. This significant increase in CO concentration is why there is lower concentrations of other gases produced in the environment due to a dilution effect. Since pyrolysis is the re-distribution of carbons in carbon substrates into three pyrogenic products. The environment is going to be more effective because the reduction into CO allows for the oxidation of pyrolysates to form CO. In conclusion the environment allows a higher yield of gases than oil and biochar. When the same process is done for TSW the trends are almost identical therefore the same explanations can be applied to the pyrolysis of TSW.
Harmful chemicals were reduced in the environment due to CO formation causing tar to be reduced. One-stepwise pyrolysis was not that effective on activating on carbon rearrangement due to the high quantities of liquid pyrolysates (tar). Two-stepwise pyrolysis for the environment allowed for greater concentrations of gases due to the second heating zone. The second heating zone was at a consistent temperature of 650 °C isothermally. More reactions between and gaseous pyrolysates with longer residence time meant that could further convert pyrolysates into CO. The results showed that the two-stepwise pyrolysis was an effective way to decrease tar content and increase gas concentration by about 10 wt.% for both TLW (64.20 wt.%) and TSW (73.71%).
Several types of thermal cleaning systems use pyrolysis:
The area of boron-hydride clusters started with the study of the pyrolysis of diborane () at ca. 200 °C. Products include the clusters pentaborane and decaborane. These pyrolyses involve not only cracking (to give ), but also recondensation. (1997). 9780750633659 ISBN 9780750633659
The synthesis of , zirconia and oxides utilizing an ultrasonic nozzle in a process called ultrasonic spray pyrolysis (USP).
When the temperature is increased from 500 to 900 °C, most PAHs increase. With increasing temperature, the percentage of light PAHs decreases and the percentage of heavy PAHs increases.
TGA can couple with Fourier-transform infrared spectroscopy (FTIR) and mass spectrometry. As the temperature increases, the volatiles generated from pyrolysis can be measured.
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