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Difference between revisions of "Hydrolysis"
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Proof reading grammer, Adding another chemical pre-treatment (ionic liquids)
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{{Infobox technology|Name=Hydrolysis|Category=Primary processing|Feedstock=lignocellulosic biomass|Product=Sugars and organic acids}} | {{Infobox technology|Name=Hydrolysis|Category=Primary processing|Feedstock=lignocellulosic biomass|Product=Sugars and organic acids}} | ||
<onlyinclude>'''Hydrolysis''' (/haɪˈdrɒlɪsɪs/; from Ancient Greek ''hydro-'' 'water', and ''lysis'' 'to unbind') is a chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.<ref>{{Cite web|year=2002|title=Hydrolysis|e-pub date=2002|date accessed=2021|url=https://en.wikipedia.org/wiki/Hydrolysis|Author=Wikipedia}}</ref> In lignocellulosic biomass, the cellulose and hemicellulose breaks down into individual sugars | <onlyinclude>'''Hydrolysis''' (/haɪˈdrɒlɪsɪs/; from Ancient Greek ''hydro-'' 'water', and ''lysis'' 'to unbind') is a chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.<ref>{{Cite web|year=2002|title=Hydrolysis|e-pub date=2002|date accessed=2021|url=https://en.wikipedia.org/wiki/Hydrolysis|Author=Wikipedia}}</ref> In lignocellulosic biomass, the cellulose and hemicellulose breaks down into individual sugars. Hemicellulose is easier to hydrolyse than cellulose.<ref>{{Cite journal|title=Dilute acid hydrolysis of lignocellulosic biomass|year=2010-01-15|author=P. Lenihan, A. Orozco, E. O’Neill, M.N.M. Ahmad, D.W. Rooney, G.M. Walker|journal=Chemical Engineering Journal|volume=156|issue=2|page=395–403|doi=10.1016/j.cej.2009.10.061}}</ref> The result of hydrolysing hemicellulose and cellulose are sugars (glucose, mannose, galactose, (C6) and xylose, arabinose (C5)) and organic acids (formic acid and acetic acid).<ref>{{Cite journal|title=Acid Hydrolysis of Lignocellulosic Biomass: Sugars and Furfurals Formation|year=2020-04-17|author=Katarzyna Świątek, Stephanie Gaag, Andreas Klier, Andrea Kruse, Jörg Sauer, David Steinbach|journal=Catalysts|volume=10|issue=4|page=437|doi=10.3390/catal10040437}}</ref> </onlyinclude> | ||
== Feedstock == | == Feedstock == | ||
=== Origin and composition === | === Origin and composition === | ||
Hydrolysis can be performed as a pretreatment on any biowaste with a high lignocellulose content. Lignocellulose is typically the nonedible part of a plant, composed of a complex of cellulose, hemi-cellulose and lignin. In order to make the | Hydrolysis can be performed as a pretreatment on any biowaste with a high lignocellulose content. Lignocellulose is typically the nonedible part of a plant, composed of a complex of cellulose, hemi-cellulose and lignin. In order to make the cellulose available for further processing, in the form of its monomeric sugars, they can be hydrolysed. Suitable feedstocks include grasses, straw, leaves, stems, shells, manure, paper waste, and others. The ratio between cellulose, hemi-cellulose and lignin varies wildly depending on the specific feedstock.<ref name=":1" /> | ||
=== Pre-treatment === | === Pre-treatment === | ||
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=== Acid === | === Acid === | ||
'''Acid hydrolysis''' is a hydrolysis process in which a protic acid is used to catalyze the hydrolysis reaction. A strong acid, such as formic, hydrochloric, nitric, phosphoric, or sulphuric acid can be used in concentrated or diluted form. '''Concentrated acid''' (10-30 %) can penetrate the lignin structure and break down the cellulose and hemicellulose to individual sugars at low | '''Acid hydrolysis''' is a hydrolysis process in which a protic acid is used to catalyze the hydrolysis reaction. A strong acid, such as formic, hydrochloric, nitric, phosphoric, or sulphuric acid can be used in concentrated or diluted form. '''Concentrated acid''' (10-30 %) can penetrate the lignin structure and break down the cellulose and hemicellulose to individual sugars at low temperature and with high yield. Downsides are the high acid consumption and high corrosion potential. These downsides are circumvented with the use of '''diluted acid''' (2-5 %). However, in the latter case, higher temperature is required, which can lead to side product formation such as furfural and 5-hydroxymethyl-furfural.<ref name=":1">{{Cite book|author=Alessandra Verardi, Isabella De Bari, Emanuele Ricca and Vincenza Calabrò|year=2012|section_title=Hydrolysis of Lignocellulosic Biomass: Current Status of Processes and Technologies and Future Perspectives|editor=Marco Aurelio Pinheiro Lima and Alexandra Pardo Policastro Natalense|book_title=Bioethanol|publisher=IntechOpen}}</ref> | ||
=== Alkali === | === Alkali === | ||
'''Alkaline hydrolysis''' refers to hydrolysis reactions using hydroxide, commonly from sodium hydroxide or calcium hydroxide. The hydroxide breaks down the lignin bonds to make the cellulose more accessible. The reaction proceeds at lower temperature and pressure and residual alkali can be recycled. However, the pretreatment does result in irrecoverable salts in the product.<ref>{{Cite journal|title=Pretreatment of lignocellulosic sugarcane leaves and tops for bioethanol production|year=2020-01-01|journal=Lignocellulosic Biomass to Liquid Biofuels|page=301–324|doi=10.1016/B978-0-12-815936-1.00010-1|author=S. Niju, M. Swathika, M. Balajii|volume=}}</ref> | '''Alkaline hydrolysis''' refers to hydrolysis reactions using hydroxide, commonly from sodium hydroxide or calcium hydroxide. The hydroxide breaks down the lignin bonds to make the cellulose more accessible. The reaction proceeds at lower temperature and pressure and residual alkali can be recycled. However, the pretreatment does result in irrecoverable salts in the product.<ref>{{Cite journal|title=Pretreatment of lignocellulosic sugarcane leaves and tops for bioethanol production|year=2020-01-01|journal=Lignocellulosic Biomass to Liquid Biofuels|page=301–324|doi=10.1016/B978-0-12-815936-1.00010-1|author=S. Niju, M. Swathika, M. Balajii|volume=}}</ref> | ||
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==== Organosolv ==== | ==== Organosolv ==== | ||
In an '''organosolv hydrolysis''' organic solvents are added to the process, usually performed at high temperatures (100-250 °C). This can be combined with a catalyst such as HCl or H<sub>2</sub>SO<sub>4</sub>.<ref name=":2" /> For example, in '''acid-acetone''' pre-treatment biowaste is treated with an acid such as phophoric acid and then mixed with pre-cooled acetone.<ref name=":0" /> | In an '''organosolv hydrolysis''' organic solvents are added to the process, usually performed at high temperatures (100-250 °C). This can be combined with a catalyst such as HCl or H<sub>2</sub>SO<sub>4</sub>.<ref name=":2" /> For example, in '''acid-acetone''' pre-treatment biowaste is treated with an acid such as phophoric acid and then mixed with pre-cooled acetone.<ref name=":0" /> | ||
'''Ionic Liquids''' | |||
Ionic liquids are '''solvents''' that can be used for biomass pretreatment, fractionation, and dissolution. During IL pretreatment, a cellulose-rich fraction can be generated through the degradation and removal of a large portion of lignin and hemicellulose <ref>{{Cite web|Author=Moyer, P., Kim, K., Abdoulmoumine, N. et al.|year=2018|title=Structural changes in lignocellulosic biomass during activation with ionic liquids comprising 3-methylimidazolium cations and carboxylate anions|e-pub date=27/09/2018|date accessed=06/12/2021|url=https://biotechnologyforbiofuels.biomedcentral.com/articles/10.1186/s13068-018-1263-0}}</ref> | |||
== Product == | == Product == | ||