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) over bar (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.