Strong Acid Cation Resin
Strong acid cation resins refer to ion exchange resins with strong acidic reactive groups such as sulfonic acid groups (-SO3H), which can be represented by R-SO3H. The shapes are white, light yellow or black granules or powder. Strong acid cation exchange resins are available in gel type, macroporous type, isoporous type and powder type, etc.
Preparation of strong acid cation exchange resins
The bead-like copolymer obtained by suspension copolymerization of styrene and divinylbenzene (they are also called white balls because of its white appearance) is swollen in dichloroethane and then sulfonated with concentrated sulfuric acid or chlorosulfonic acid to introduce sulfonic acid groups The exchange group, and then the corresponding post-treatment, can prepare the gel-type strong acid ion exchange resin. If an inert solvent with a pore-forming effect is added during the copolymerization, a macroporous resin can be prepared.
Strong acid cation resins can be used as catalysts for the conversion of benzaldehyde and indole into bis-indole methane derivatives. Common catalysts in the literature are mostly Lewis acids, such as FeSO4. In contrast, ion exchange resins have a higher specific surface area, are selective and eco-friendly, and can be recycled and reused many times without loss of activity. Therefore, it is considered to be the most effective for the reaction of indole with aldehydes. The reaction uses water as a solvent to realize that the catalyst can be recycled for 6 times, and a variety of bis-indole methane compounds can be obtained with a higher yield. (Zhang Ruize, et al., 2019) Strong acid cation resins can also be used to extract carbon dioxide from seawater. These carbon dioxide and hydrogen can be combined to synthesize jet fuel at sea. The working principle of ion exchange materials is to exchange hydrogen ions on the cation resin in solution. Ion exchange resins offer several advantages for this particular application because they are generally inexpensive and durable, and can operate at high flow rates in various aqueous media. In addition, the selectivity of the resin can be adjusted using a mixed bed or specific functional groups during resin synthesis. The use of deionized water as a possible substitute for strong acids also proves that the cation exchange resin is easy to regenerate.(Willauer H D, et al., 2010)
- Catalytic reaction
- Adsorbed ion
- Food Industry
- Zhang Ruize, et al. Strong-Acid Cation Exchange Resin Catalyzed Synthesis of Bis(indolyl)methanes in Water[J]. Chinese Journal of Organic Chemistry, 2019.
- Willauer H D, et al. Extraction of CO2 from Seawater and Aqueous Bicarbonate Systems by Ion-Exchange Resin Processes[J]. Energy & Fuels, 2010.