Novel silicon free defoaming agents, based on alkylacrylates, for petroleum: Effect of the molecular weight on their efficiency

A series of new free silicone defoaming agents, based on polybutyl acrylate (PBuA), was synthesized by emulsion polymerization, varying the weight average molecular weight (M-w) by using different amounts of initiator or chain transfer agent. PBuA homopolymers were assessed at dosages of 250, 500, and 750 ppm as foam suppressors of gasified heavy crude oil employing a static method, based on the sudden pressure drop of the system. A PBuA homopolymer with an adequate weight average molecular weight showed the highest activity to suppress crude oil foam, reaching an abatement of 80%, being more efficient than a commercial silicon-based defoamer. The new silicon free defoamers based on PBuA are innocuous during the refining stages and lower cost than conventional siloxanes; therefore, these acrylic homopolymers can be used in industrial separation tanks to eliminate petroleum foams, replacing antifoaming agents based on silicon, which cause catalyst poisoning.