Application of Gemini Surfactants as Diesel Fuel Wax Dispersants

Gemini surfactants were synthesized and evaluated as wax dispersants (WDs) or wax antisettling additives (WASAs) in crude oil derived diesel. In combination with styrene-C18 methacrylate statistical copolymers as coadditives, aliphatic flexible (class A) and rigid aromatic spacer (class B) geminis with two or three ionic head groups having C18 chain length were investigated. The copolymers were prepared via a controlled radical polymerization technique, atom transfer radical polymerization (ATRP). Crystallization studies in crude diesel revealed a structure-activity relationship between the gemini surfactants in conjunction with the polymeric additives. The lower molecular weight polymeric additive together with the flexible spacer geminis decreased the cold filter plugging point (CFPP) by about 11 degrees C with efficiency decreasing with aromatic geminis. The higher molecular weight polymeric additive in combination with the rigid bifunctional aromatic gemini gave a Delta CFPP of 12 degrees C.