MCRS Naphthenic Acids Serve in a Wide Variety of Applications

Merichem Chemicals & Refinery Services LLC (MCRS) naphthenic acids are a naturally occurring, complex mixture of cycloaliphatic carboxylic acids recovered from petroleum distillates. Readily available worldwide, commercial naphthenic acids include crude, semi-refined, refined and high purity grades. Naphthenic acids can replace natural fatty acids, tall oil acids and synthetic acids in numerous performance-oriented applications requiring these advantages:

• Excellent oxidative stability and compatibility
• High solubility in hydrocarbons and oils
• Low solubility in water
• Low viscosity and surface active properties

The unique properties inherent in the cycloaliphatic structure, coupled with MCRS’ unequaled processing capabilities, allow our naphthenic acid derivatives to be widely used in wood treating, corrosion inhibitors, emulsifiers, defoamers, paint and ink driers, tire cord adhesives, fuel additives, cutting oils and vinyl stabilizers.

Unique Physical and Chemical Properties Generate Broad Applications

Naphthenic acids are composed predominately of alkyl-substituted cycloaliphatic carboxylic acids with smaller amounts of acyclic aliphatic (paraffinic or fatty) acids. The cycloaliphatic acids include single rings and fused multiple rings. As shown in Figure 1, the carboxyl group is usually bonded or attached to a side chain rather than directly to the cycloaliphatic ring. The location of the carboxyl group can make naphthenic acids more reactive than resin acids or neo acids. Aromatic olefinic, hydroxy and dibasic acids are present as minor components of naphthenic acids.

Naphthenic acids are liquids with low freezing points and a wide boiling point range (250-350ºC). They are completely soluble in organic solvents and oils but insoluble in water.

Chemically, naphthenic acids behave like typical carboxylic acids with acid strengths similar to those of the higher fatty acids; dissociation constants are on the order of 10⁵-10^-6 (pKa ~ 5-6). Naphthenic acids are slightly weaker than low molecular weight carboxylic acids, such as acetic acid.

Figure 1 - Naphthenic Acids
R represents multiple alkyl groups or fused cycloaliphatic rings.

While the major use of naphthenic acids has been in the production of metal soaps, they also can react to form esters, amine salts, amides, imidazolines and many other derivatives. Compared to fatty acid derivatives, naphthenic acid derivatives offer many advantages, particularly their high stability to oxidation and their solubility in hydrocarbons.

MCRS Naphthenic Acids - An Unsurpassed Range of Grades and Properties

MCRS produces naphthenic acids from refinery-based raw material sources found around the world. MCRS continues to develop raw material sources as new, highly acidic petroleum reserves are developed. Our extensive raw material base and expert manufacturing capabilities enable us to custom design naphthenic acids meeting any customer specification.

MCRS can supply a variety of crude, semi-refined and refined naphthenic acid products ranging in acid number from 160 to 260. Through a patented process, very high purity acids are also available with acid numbers ranging from 220 to 310.

When determining the type of naphthenic acid to evaluate for your application, consider three key factors: acid number, color and unsaponifiables.

PRODUCT GRADE	TYPICAL USES	ACID NUMBER (mg KOH/g)	COLOR (Gardner Scale)	UNSAPONIFIABLES (% by Wt)
Crude	Corrosion inhibitors Wood preservatives	160–220	Dark—no color specification	7–30
Semi-refined	Lubricant additives Wood preservatives	180–260	Dark—no color specification	5–10
Refined	Driers for paints & inks Lubricant additives Fuel additives Heat/UV stabilizers Cutting oils	200–260	3 minimum	4–8
High Purity Refined	Tire cord adhesive promoter Driers for paints & inks Esters	220–310	3 minimum	3 maximum
Specialty Blends (naphthenic acids/ non-naphthenics)	Driers for paints & inks	240–310	3 minimum	3–5

For technical assistance in selecting an acid for your application or to obtain samples for evaluation, call our toll-free customer service line (U.S. only) at 1-800-795-4980, or click Contacts or Sample Request.