十八烷基己基甲基羧基甜菜碱的合成及性能

Synthesis and Properties of Stearylhexylmethyl Carboxyl Betaine

摘要:

以硬脂酸和己酸为原料合成了不对称双长链烷基羧基甜菜碱——十八烷基己基甲基羧基甜菜碱(C18+6B)，测定了C18+6B的表面活性，并与总碳原子数相等的对称型双十二烷基甲基羧基甜菜碱(diC12B)进行比较，以了解表面活性剂分子结构对性能的影响。结果表明，C18+6B的表面活性与diC12B基本相当，但水溶性远好于diC12B。作为无碱驱油用表面活性剂，C18+6B对大庆原油来说HLB值略偏高，45 ℃ 下单独使用能将大庆原油/地层水界面张力降至10-2mN/m数量级，在大庆油砂上的饱和吸附量比diC12B低30%。C18+6B单独能将C7~C9正构烷烃/大庆地层水界面张力降至10-3mN/m数量级，而通过与亲油性更强的diC12B以及亲水性甜菜碱复配后，能将大庆原油/地层水界面张力降至10-3mN/m数量级，并能显著改善配方的水溶性。

Abstract:

For understanding effects of molecular structure on properties of surfactants an asymmetric double long-chain alkyl betaine, stearylhexylmethyl carboxyl betaine (C18+6B), was synthesized using stearic acid and hexanoic acid as starting materials and its surface active properties were measured and compared with that of didodecyl methyl carboxyl betaine(diC12B), a symmetric double long-chain betaine with equal total carbon number. The results show that C18+6B has a surface activity similar to that of diC12B in general, but displays an aqueous solubility much better than that of diC12B. As a surfactant for surfactant-polymer flooding free of alkali, C18+6B seems to be slightly less hydrophobic against Daqing crude oil, which solely can reduce the Daqing crude oil/connate water interfacial tension (IFT) to 10-2 mN/ m magnitude and gives a saturated adsorption 30% lower than that of diC12B at Daqing sandstone/water interface at 45 C. C18+6B solely can reduce C7-C9 n-alkanes/connate water IFT to 10-3 mN/m magnitude at 45 C, and can reduce the daqing crude oil/connate water IFT to 10-3 mN/m magnitude at 45 C by mixing with the more hydrophobic surfactant diC12B and other hydrophilic betaine surfactant, where the aqueous solubility of the formulation is greatly improved by the presence of C18+6B.