Solid acids are acids that are insoluble in the reaction medium. They are often used as heterogeneous catalysts. Many solid acids are zeolites.[1] A variety of techniques are used to quantify the strength of solid acids.[2]
Examples
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Examples of inorganic solid acids include silico-aluminates (zeolites, alumina, silico-aluminophosphate), and sulfated zirconia. Many transition metal oxides are acidic, including titania, zirconia, and niobia.[3] Such acids are used in cracking.[1] Many solid Brønsted acids are also employed industrially, including polystyrene sulfonate, solid phosphoric acid, niobic acid, and heteropolyoxometallates.[4]
Applications
editSolid acids are used in catalysis in many industrial chemical processes, from large-scale catalytic cracking in petroleum refining to the synthesis of various fine chemicals.[5]
One large scale application is alkylation, e.g., the combination of benzene and ethylene to give ethylbenzene. Another application is the rearrangement of cyclohexanone oxime to caprolactam.[6][7][8] Many alkylamines are prepared by amination of alcohols, catalyzed by solid acids.
Acylations are also catalyzed by solid acids.[9]<ref>Sartori, Giovanni; Maggi, Raimondo (2011). "Update 1 of: Use of Solid Catalysts in Friedel−Crafts Acylation Reactions". Chemical Reviews. 111 (5): PR181–PR214. doi:10.1021/cr100375z. PMID 21488695.</ref
Solid acids can be used as electrolytes in fuel cells.[3]
References
edit- ^ a b Kresge, Charles T.; Dhingra, Sandeep S. (2004). "Molecular Sieves". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.1315120511210812.a01.pub2. ISBN 978-0-471-48494-3.
- ^ Zheng, Anmin; Liu, Shang-Bin; Deng, Feng (2017). "31P NMR Chemical Shifts of Phosphorus Probes as Reliable and Practical Acidity Scales for Solid and Liquid Catalysts". Chemical Reviews. 117 (19): 12475–12531. doi:10.1021/acs.chemrev.7b00289. PMID 28952317.
- ^ a b Boysen, Dane A.; Uda, Tetsuya; Chisholm, Calum R. I.; Haile, Sossina M. (2004-01-02). "High-Performance Solid Acid Fuel Cells Through Humidity Stabilization" (PDF). Science. 303 (5654): 68–70. Bibcode:2004Sci...303...68B. doi:10.1126/science.1090920. ISSN 0036-8075. PMID 14631049. S2CID 10829089.
- ^ Busca, Guido (2007-11-01). "Acid Catalysts in Industrial Hydrocarbon Chemistry". Chemical Reviews. 107 (11): 5366–5410. doi:10.1021/cr068042e. ISSN 0009-2665. PMID 17973436.
- ^ "Solid Acid Catalysis: From Fundamentals to Applications". CRC Press. Retrieved 2016-09-15.
- ^ Röper, Michael; Gehrer, Eugen; Narbeshuber, Thomas; Siegel, Wolfgang (15 June 2000), "Acylation and Alkylation", Ullmann's Encyclopedia of Industrial Chemistry, John Wiley & Sons, Ltd, doi:10.1002/14356007.a01_185, ISBN 978-3-527-30673-2, retrieved 2022-01-18
- ^ Corma, A. (1995). "Inorganic Solid Acids and Their Use in Acid-Catalyzed Hydrocarbon Reactions". Chemical Reviews. 95 (3): 559–614. doi:10.1021/cr00035a006.
- ^ Busca, Guido (2007). "Acid Catalysts in Industrial Hydrocarbon Chemistry". Chemical Reviews. 107 (11): 5366–5410. doi:10.1021/cr068042e. PMID 17973436.
- ^ Sartori, Giovanni; Maggi, Raimondo (2006). "Use of Solid Catalysts in Friedel−Crafts Acylation Reactions". Chemical Reviews. 106 (3): 1077–1104. doi:10.1021/cr040695c. PMID 16522017.