Preparation of cationic polyacrylate W/O crude oil emulsion demulsifier by free-radical solution polymerization

The block polyether demulsifier prepared by ring-opening polymerization of ethylene oxide and propylene oxide under high temperature and high pressure is the most widely used demulsifier for water in crude oil emulsion. It has the high synthesis risk and cost. Therefore, the development of non-block polyether demulsifier has attracted more and more attention. In this article, a new type of demulsifier was sythesized by radical polymerization of acrylate and cationic monomer. It was found that the copolymer PMA-co-PDBC of methyl acrylate (MA) and benzyldimethyl [2-[(1-oxoallyl)oxy] ethyl] ammonium chloride (DBC) synthesized in the mixed solvent of dipropylene glycol methyl ether and water had a good performance. When dosage of PMA-co-PDBC was 200 mg/L, the dehydration rate of water in crude oil emulsion with 50% water content can reach 80% at 80°C within 4 h. Structural and interface properties analysis presented that PMA-co-PDBC had a microblock structure similar with block polyether and it can effectively reduce the strength of W/O interfacial film to realize the demulsification. Although the demulsification performance of PMA-co-PDBC was not better than block polyether, its preparation safety and cost are much better. The results of this article can provide a new option for the development of crude oil demulsifier.