Dow Water & Process Solutions

Inhibitor and Stabilizer Removal

Many monomers used today are stabilized with inhibitors such as hydroquinone, hydroquinone monomethyl ether or 4-tert-butylcatechol. During polymerization, enough catalyst must be added to overcome the effects of these stabilizers. Variations in the storage time and conditions for the monomer will vary the depletion levels of the stabilizers. In addition, stabilizers may affect critical polymerization conditions such as chain length and branching. For critical applications, removal of these stabilizers is desired.

Quinones and their analogues can be removed with anion exchange resins and adsorbents. The conjugated ring of the stabilizer associates with the styrenic ring of the anion exchange resin and the ionic groups pair up to effectively remove the stabilizer from solution. For stabilizer removal, Dow offers DOWEX™ MONOSPHERE™ 550A (OH) and DOWEX MARATHON™ MSA . Both products will treat about 50 bed volumes of monomer containing 100 ppm stabilizer at a flow rate of 2 to 6 bed volumes per hour.

To remove stabilizers from non-aqueous, organic systems, a dry ion exchange resin is needed to facilitate intimate interaction of the solvent with the exchange site. DOWEX MONOSPHERE 550A (OH) and DOWEX MARATHON MSA are sold water wet. They can be dried in a vented oven at 100°C or by washing them with a dry, polar solvent (methanol, ethanol, isopropanol, acetone, etc.).

DOWEX Ion Exchange Resins

Product	Description	Type	Matrix	Total Exchange Capacity* eq/l (kgr/ft3)	Available Forms
DOWEX MONOSPHERE 550A (OH)	A uniform particle size strong base anion exchange resin for mixed bed demineralization and condensate polishing applications.	Type I Strong Base Anion	Styrene-DVB, Gel	1.1 (24.0)	OH-
DOWEX MARATHON MSA	Uniform particle size, high capacity, macroporous strong base anion exchange resin for water demineralization applications.	Type I Strong Base Anion	Styrene-DVB, Macroporous	1.1 (24.0)	Cl-