Synthesis And Properties Of Betaine Zwitterionic Surfactants With Branched Structure

It is an important means to enhanced oil recovery(EOR) and its economic benefit is considerable. With the oil price at high level for a long time and the existing fields turning into the aging stage gradually, the economic benefit of EOR will be more and more significant.A series of betaine zwitterionic surfactants were designed and synthesized by the series of branched fatty alcohol polyoxyethylene ether. And the surface and interface properties of the synthesized surfactants were studied.Firstly, by series of fatty alcohol polyoxyethylene ether as the raw material, the intermediate of fatty alcohol polyoxyethylene glycidyl ether was synthesized, and they are named as GEC13(5),GEC13(7) and GEC13(9). The zwitterionic surfactants of{N, N-dimethyl-N-[2-hydroxy-3-branched chain alkyl (ethylene oxide)n] ammonio} acetate namely GzC13(5),Gz,C13(7) and G/C13(9) was synthesized further. The structure of intermediate and product were characterized mass spectrum. The method of removing NaOH in fatty alcohol polyoxyethylene glycidyl ether is also proposed.Secondly, the surface properties (25℃) of fatty alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene glycidyl ether and betaine zwitterionic surfactants with branched structure were studied. The results indicate that the cmc of GzC13(5),GzC13(7) and GzC13(9) were0.032g.L-1,0.051g.L-1and0.074g.L-1,respectively, and the γeme were27.14mN.m-1,29.32mN.m-1and31.54mN.m-1, respectively. When the carbon chain structure was same, with the number of EO increased in the hydrophilic group, the cmc and γcmc of the surfactants were also increased.Finally, the oil/water interface performance (45℃) of betaine zwitterionic surfactants with branched structure was researched. The results show that with the number of EO increases, when the surfactant was used alone, all the oil/water interfacial tension was reduced. The ability of reducing oil/water interfacial tension of surfactant was the strongest to the Daqing No.2factory oil, the No.1factory oil was next and No.4factory oil was the weakest. When the GzC13(7) compound with NaCl, the oil/water interfacial tension could be reduced to10-3mN/m to No.2factory of Daqing. When GzC13(5) compound with Na2CO3, the oil/water interfacial tension could be reduced to10-3mN/m to Daqing No.1and No.4factory There would be no synergies effect observed among the surfactants.