Editing Thermal depolymerization (section)

===Plastics===
[[Plastic waste]] consists mostly of [[commodity plastics]] and may be actively [[waste sorting|sorted]] from [[municipal waste]]. Pyrolysis of mixed plastics can give a fairly broad mix of chemical products (between about 1 and 15 carbon atoms), including gases and aromatic liquids.<ref>{{cite journal |last1=Kaminsky |first1=W. |last2=Schlesselmann |first2=B. |last3=Simon |first3=C.M. |title=Thermal degradation of mixed plastic waste to aromatics and gas |journal=Polymer Degradation and Stability |date=August 1996 |volume=53 |issue=2 |pages=189–197 |doi=10.1016/0141-3910(96)00087-0}}</ref> Catalysts can give a better-defined product with a higher value.<ref>{{cite journal |last1=Aguado |first1=J. |last2=Serrano |first2=D. P. |last3=Escola |first3=J. M. |title=Fuels from Waste Plastics by Thermal and Catalytic Processes: A Review |journal=Industrial & Engineering Chemistry Research |date=5 November 2008 |volume=47 |issue=21 |pages=7982–7992 |doi=10.1021/ie800393w}}</ref> Likewise, [[hydrocracking]] can be employed to give [[Liquefied petroleum gas|LPG]] products. The presence of [[PVC]] can be problematic, as its thermal depolymerization generates large amounts of [[hydrogen chloride|HCl]], which can corrode equipment and cause undesirable chlorination of the products. It must be either excluded or compensated for by installing dechlorination technologies.<ref>{{cite journal |last1=Fukushima |first1=Masaaki |last2=Wu |first2=Beili |last3=Ibe |first3=Hidetoshi |last4=Wakai |first4=Keiji |last5=Sugiyama |first5=Eiichi |last6=Abe |first6=Hironobu |last7=Kitagawa |first7=Kiyohiko |last8=Tsuruga |first8=Shigenori |last9=Shimura |first9=Katsumi |last10=Ono |first10=Eiichi |title=Study on dechlorination technology for municipal waste plastics containing polyvinyl chloride and polyethylene terephthalate |journal=Journal of Material Cycles and Waste Management |date=June 2010 |volume=12 |issue=2 |pages=108–122 |doi=10.1007/s10163-010-0279-8|bibcode=2010JMCWM..12..108F |s2cid=94190060 }}</ref> [[Polyethylene]] and [[polypropylene]] account for just less than half of global plastic production and, being pure [[hydrocarbons]], have a higher potential for conversion to fuel.<ref name=2011CommercialRev>{{cite journal |last1=Butler |first1=E. |last2=Devlin |first2=G. |last3=McDonnell |first3=K. |title=Waste Polyolefins to Liquid Fuels via Pyrolysis: Review of Commercial State-of-the-Art and Recent Laboratory Research |journal=Waste and Biomass Valorization |date=1 August 2011 |volume=2 |issue=3 |pages=227–255 |doi=10.1007/s12649-011-9067-5|bibcode=2011WBioV...2..227B |hdl=10197/6103 |s2cid=98550187 |hdl-access=free }}</ref> Plastic-to-fuel technologies have historically struggled to be economically viable due to the costs of collecting and sorting the plastic and the relatively low value of the fuel produced.<ref name=2011CommercialRev /> Large plants are seen as being more economical than smaller ones,<ref>{{cite journal |title=Pyrolysis of plastic waste for production of heavy fuel substitute: A techno-economic assessment |journal=Energy |date=15 April 2018 |volume=149 |pages=865–874 |doi=10.1016/j.energy.2018.02.094|last1=Fivga |first1=Antzela |last2=Dimitriou |first2=Ioanna |bibcode=2018Ene...149..865F |url=http://eprints.nottingham.ac.uk/50558/3/A.%20Fivga%202018%20Authors%20copy.pdf }}</ref><ref>{{cite journal |last1=Riedewald |first1=Frank |last2=Patel |first2=Yunus |last3=Wilson |first3=Edward |last4=Santos |first4=Silvia |last5=Sousa-Gallagher |first5=Maria |title=Economic assessment of a 40,000 t/y mixed plastic waste pyrolysis plant using direct heat treatment with molten metal: A case study of a plant located in Belgium |journal=Waste Management |date=February 2021 |volume=120 |pages=698–707 |doi=10.1016/j.wasman.2020.10.039|pmid=33191052 |bibcode=2021WaMan.120..698R |s2cid=226972785 |hdl=10468/12445 |hdl-access=free }}</ref> but require more investment to build.

The method can, however, result in a mild net-decrease in [[greenhouse gas]] emissions,<ref>{{cite journal |last1=Benavides |first1=Pahola Thathiana |last2=Sun |first2=Pingping |last3=Han |first3=Jeongwoo |last4=Dunn |first4=Jennifer B. |last5=Wang |first5=Michael |title=Life-cycle analysis of fuels from post-use non-recycled plastics |journal=Fuel |date=September 2017 |volume=203 |pages=11–22 |doi=10.1016/j.fuel.2017.04.070|osti=1353191 |doi-access=free |bibcode=2017Fuel..203...11B }}</ref> though other studies dispute this.  For example, a 2020 study released by Renolds on their own Hefty EnergyBag program shows net greenhouse gas emissions. The study showed then when all cradle-to-grave energy costs are tallied, burning in a cement kiln was far superior.  Cement kiln fuel scored a −61.1&nbsp;kg {{CO2}} equivalents compared to +905&nbsp;kg {{CO2}} eq.  It also fared far worse in terms of landfill reduction vs. kiln fuel.<ref name="Table ES.1 – End of Life GWP Summary Table">{{cite web |last1=Sustainable Solutions |title=Hefty® EnergyBag® Program Life Cycle Assessment |url=https://www.hefty.com/sites/default/files/2021-01/Hefty-EnergyBag-Program-Life-Cycle-Assessment-Aug-2020.pdf |website=hefty.com |publisher=Reynolds/Sustainable Solutions |access-date=21 June 2022 |ref=Table E51}}</ref> Other studies have confirmed that plastics pyrolysis to fuel programs are also more energy intensive.<ref>{{cite news |last1=Brock |first1=Joe |last2=VOLCOVICI |first2=VALERIE |last3=Geddie |first3=John |title=The Recycling Myth |url=https://www.reuters.com/investigates/special-report/environment-plastic-oil-recycling/ |access-date=21 June 2022 |work=Reuters}}</ref><ref>{{cite web | url=https://www.theatlantic.com/ideas/archive/2022/05/single-use-plastic-chemical-recycling-disposal/661141/ | title=Plastic Recycling Doesn't Work and Will Never Work | website=[[The Atlantic]] | date=30 May 2022 }}</ref>

For tire waste management, [[Tire recycling#Tire pyrolysis|tire pyrolysis]] is also an option. Oil derived from tire rubber pyrolysis contains high sulfur content, which gives it high potential as a pollutant and requires [[hydrodesulfurization]] before use.<ref>{{cite journal|author1=Choi, G.-G. |author2=Jung, S.-H. |author3=Oh, S.-J. |author4=Kim, J.-S. |title=Total utilization of waste tire rubber through pyrolysis to obtain oils and {{CO2}} activation of pyrolysis char|journal=Fuel Processing Technology|volume=123|pages=57–64|doi=10.1016/j.fuproc.2014.02.007|year=2014}}</ref><ref>Ringer, M.; Putsche, V.; Scahill, J. (2006) [http://www.nrel.gov/docs/fy07osti/37779.pdf Large-Scale Pyrolysis Oil Production: A Technology Assessment and Economic Analysis] {{webarchive|url=https://web.archive.org/web/20161230234405/http://www.nrel.gov/docs/fy07osti/37779.pdf |date=2016-12-30 }}; NREL/TP-510-37779; National Renewable Energy Laboratory (NREL), Golden, CO.</ref> The area faces legislative, economic, and marketing obstacles.<ref name='j.rser.2013.02.038'>{{cite journal  | year = 2013 | title = Waste tyre pyrolysis – A review, Renewable and Sustainable | journal = Energy Reviews | volume = 23 | pages = 179–213 | doi = 10.1016/j.rser.2013.02.038 | last1 = Martínez | first1 = Juan Daniel | last2 = Puy | first2 = Neus | last3 = Murillo | first3 = Ramón | last4 = García | first4 = Tomás | last5 = Navarro | first5 = María Victoria | last6 = Mastral | first6 = Ana Maria | bibcode = 2013RSERv..23..179M }}</ref> In most cases, tires are simply incinerated as [[tire-derived fuel]].