Synthesis And Properties Of Di-hydrophobic Betaine With Amide Group

Zwitterionic betaine surfactants have been used as EOR surfactant in ASP flooding. Di-12 amide betaine was a new improved surfactant. It has better lipophilicity which owing to its two hydrophobic long-chain alkyl. This was beneficial to reduce oil-water interfacial tension. Due to two amide groups in the structure, the product has good chemical properties, such as biodegradability, mild, and chemical stability.A new-style zwitterionic surfactant with amide group was synthesized in this paper. Due to its low-cost and high-powered, a new synthesis route of the three-step method was introduced. In this experiment, intermediates technoligical conditions, product structure, product technoligical condition, product surface and interface properties were investigated. Study and analyze the chemical stability of the target product, and to examine it as EOR surfactant.The total results as following:N,N-bis-(dodecylamidoethyl)-amine was synthesized from dodecanoic acid and diethylenetriamine by amidation. Optimum technics conditions were obtained by orthogonal experiment: n(diethylenetriamine):n(dodecanoic acid)=1:2.0, reaction temperature was 170℃and reaction time was 8h, the catalyst amount used was 0.5%.N,N-bis(dodecylamidoethyl)-N-methylamine starting from formic acid and formaldehyde, ethanol as solvent. Optimum technics conditions were obtained by orthogonal experiment: in a molar ratio 1:2.3:1.7 of the intermediate and formic acid as well as formaldehyde at 85℃for 10h.N,N-bis(dodecylamidoethyl)-N-methyl-N-carboxymethylammonium betaine can be synthesized by reacting, N,N-bis(dodecylamidoethyl)-N-methylamine with sodium chloroacetate, the reaction was a two phase reaction. The results show that the critical micelle concentration of the product is 1.2×10-5 mol·L-1,γcmc is 25.38mN/m. The saturated adsorption of the surfactant at air/water interface is so high that the cross section area of each molecule in the monolayer is 0.28nm2, which is much lower than that of sodium dodecyl sulfate, 0.5nm2. The product has a good tolerance to electrolytes. By mixing with other surfactants, they can reduce Daqing crude oil/water interfacial tension to an order of 10-4mN/m in a total surfactant concentration range of 0.05～0.3wt.% at 45℃.