Alkylation of Aromatics

Alkylation of Aromatics
Alkylphenols

The production of Alkylphenols is in the order of 500 000 metric tons per year. Alkylphenols range generally from C1 to C₁₂ alkyls. Alkylphenols such as butylphenols, octylphenol, nonylphenol, and dodecylphenol are used in herbicides, gasoline additives, dyestuffs, polymer additives, surfactants, lubricant oil additives and antioxidants.

Alkylphenols can be synthesized using several methods, including alkylation of a phenol using different types of catalysts, hydroxylation of an alkylbenzene, dehydrogenation of an alkylcyclohexanol, or ring closure of an appropriately substituted acyclic compound. The choice of approach depends on the target alkylphenol, availability of raw materials, and cost of processing.

The technique generally used to synthesize alkylphenols is Friedel-Crafts alkylation. C₃ to C₁₂ alkylates are generally made through acid catalysis using sulphuric acid, BF3 or strong acid catalysts like Amberlyst™ 15Dry, Amberlyst™ 35Dry or Amberlyst™ 36Dry. The choice of the Amberlyst™ catalyst depends very much on the type of alkene.

Amberlyst™ 35DRY and Amberlyst™ 36DRY are the highest performing polymer based catalysts and represent the benchmark for phenol alkylation.

Reaction of Phenol and branched olefins

Phenol reacts with branched olefins, CnH₂n, including propylene tetramer, propylene trimer and diisobutylene, in presence of a dry macroporous strongly acidic catalyst at 120° to 150 °C to give alkylphenols. Amberlyst™ dry catalysts have been especially designed for these applications and have been dried to an optimal degree of moisture in order to ensure a high conversion rate and excellent selectivity. Their physical stability makes them well suited to stirred tank reactors and allows an extremely efficient separation from the reactants. Their optimized pore size distribution gives good diffusion rates and a long life.

Rohm and Haas manufactured these alkylphenols based on the resin catalyst process for more than 20 years and licensed its technology around the world. This long experience was fruitful to Rohm and Haas in developing high quality resin catalysts for the alkylphenol industry.

Typical Process conditions

Influent Composition	Phenol and alkene
Influent Temperature	110 - 150 °C
Conversion per pass	up to 99%
Typical Catalyst life	up to 2 years

Recommended Catalysts

Amberlyst™ 15Dry	Good alkylation catalyst for processes operating below 120°C, excellent physical stability
Amberlyst™ 35Dry	High acid capacity and excellent thermal and physical stability
Amberlyst™ 36Dry	High acid capacity, excellent thermal stability, kinetics and physical stability

Amberlyst™ catalysts for phenol alkylation are approved by all major producers.

For sampling, pricing and availability of AMBERLYSTT catalysts please contact your Rohm and Haas sales representative.