Phenol Alkylation

Alkylated phenols are widely used as additives in gasoline, lubricants, and a host of consumer products. They are made by the acid catalyzed condensation of an alkene with phenol via the general reaction shown below. While the most common alkylated phenols are nonylphenol and dodecylphenol, other chain length and branched products are also produced.

There are two basic technologies used for the manufacture of alkylated phenols; homogeneous acid catalysis (with sulfuric acid or boron trifluoride gas) and heterogeneous acid catalysis. The advantages of heterogeneous catalysts are described below.

For some specialty applications, the alkyl chain may be so large or branched that it does not couple well with the catalyst. In these cases, Dow offers a wide variety of fine mesh resins (183KB PDF) with varying levels of cross-linking that allow interaction of the catalyst site with these cumbersome alkyl groups. Cross-linking levels range from 2 to 8% and particle sizes from 300 microns to 37 microns.

Features and Benefits of DOWEX Catalysts in Phenol Alkylation

Low Residual Acidity – DOWEX™ dry catalysts are produced with special attention to low levels of residual acidity. Some reactions, particularly during start-up, are very sensitive to catalysts that are "too hot", where higher levels of by-products are formed. Often these symptoms disappear with further use. In some cases, this problem is due to residual acid left in the catalyst from manufacture. DOWEX DR-2030 catalysts are specially prepared to reduce the levels of residual acidity thereby reducing by-product formation in sensitive reactions.

Improved Productivity With Uniform Particle Size Products – Continuous catalyst operations in packed beds must be optimized for maximum throughput. Kinetic limitations for diffusion of reactants into the catalyst sites and diffusion of product back out into the bulk solution should be considered. Because of their relatively long diffusion paths, the largest beads are the most kinetically limited with an effective "dead zone" present at the center of the bead. Pressure drop through the bed is another potential limitation. While the smallest beads have very fast diffusional kinetics, they contribute more to the pressure drop. DOWEX MONOSPHERE™ DR-2030 catalyst is made by a patented process resulting in excellent uniformity of bead size. Many customers have experienced as much as 15% increase in productivity when switching from a standard bead size to uniform particles like DOWEX MONOSPHERE DR-2030.

DOWEX Resins

Product	Description	Type	Matrix	Total Exchange Capacity* eq/l (kgr/ft3)	Available Forms
DOWEX DR-2030	Dry acid catalysts for chemical processing.	Strong Acid Cation	Styrene-DVB, Macroporous	4.7 eq/kg	H+
DOWEX MONOSPHERE DR-2030	Dry acid catalysts for chemical processing.	Strong Acid Cation	Styrene-DVB, Macroporous	4.7 eq/kg	H+
DOWEX M-43	Corrosion control with DOWEX M-43 ion exchange resin.	Weak Base Anion	Styrene-DVB, Macroporous	1.55	FB (Free Base) form