The Synthesis And Performance Investigation Of Sodium Alkylphenol Polyoxypropylene Ether Sulfates /φ - Sulfonates

The traget of this paper is to prepare several surfactants with a certain capacity of temperature resistance, salt-tolerant and tolerance to hard water. Seven types of alkoxylated anionic surfactants were synthesized from nonylphenol by ethoxylation/propoxylation, sulfonation/sulfation followed by neutralization, some properties of these seven surfactants were measured, especially equilibrium interfacial tension.Three types of nonylphenol polyoxypropylene ether (NPP-n), with the value of n is 3, 6 and 9, were synthesized from nonylphenol by propoxylation using propylene oxide (PO).Two types of polyoxypropylene modified anionic surfactants sodium nonylphenol propoxylate(n)-φ-sulfonates (φ-NPPS-n) were synthesized from NPP-3 or NPP-6 by sulfonation at the phenyl ring and followed by neutralization. As an example ofφ-NPPS-6, its structure was identified by IR, ESI-MS and ¹H-NMR. The conditions of sulfonation processes were optimized by the Single-factor experimental design, and the optimized reaction conditions were as followings: 1, 2-dichloroethane as solvent, aging-time 1 h, aging-temperature 50℃, n(ClSO₃H) : n(NPP-6) = 3.5. In the same sulfonation way, one type of anionic-nonionic surfactant sodium nonylphenol polyoxyethylene ether (3)-φ-sulfonate (φ-NPES-3) was synthesized from commercial NPE-3.Three types of extended anionic surfactants sodium nonylphenol propoxylate sulfates (NPPS-n) were synthesized from NPP-3, NPP-6 and NPP-9 by sulfation in the end hydroxyl group and followed by neutralization. As an example of NPPS-6, its structure was identified by IR and ¹H-NMR. The conditions of sulfation processes were also optimized by the Single-factor experimental design, and the optimized reaction conditions were as followings: 1, 2-dichloroethane as solvent, aging-time 15 min, aging-temperature 35℃, n(ClSO₃H) : n(NPP-6) = 1.4. In the same sulfation way, the other type of anionic-nonionic surfactant sodium nonylphenol polyoxyethylene ether (3) sulfate (NPES-3) was synthesized from commercial NPE-3.Some properties of these surfactants were measured such asγcmc, cmc, salt-tolerant, Ca²⁺ stability, thermal and pH hydrolysis stability and interfacial tension. The main experimental results and conclusions can be listed as followings:(1) The two types of anionic-nonionic surfactants have good salt-tolerant and Ca²⁺ stability. The salt-tolerance of NPES-3 andφ-NPES-3 were 28 and 155 g/L of NaCl, while the calcium inon stability were 945.4 and >3516.2 mg/L. But their interfacial performances were poor. Changing NaCl content in oil-water system, the equilibrium interfacial tension was still above 1 mN/m. Therefore, these types of anionic-nonionic surfactants were not suitable for surfactant flooding.(2) The two types of polypropylene modified surfactants had better salt-tolerant and Ca²⁺ stability than the extended anionic surfactants with the same polyether chain lengths, while their interfacial performance were superior to the aforementioned anionic-nonionic surfactants. The results showed that their equilibrium interfacial tension maintained above 0.1 mN/m. Therefore, these types of surfactants were also not suitable for surfactant flooding. (3) The three types of extended anionic surfactant had good interfacial performance, and their thermal hydrolysis stability, salt-tolerant and Ca²⁺ stability could basically meet the requirements of surfactant flooding. The minimum equilibrium interfacial tension of NPPS-3, NPPS-6 and NPPS-9 without assistance of co-surfactant alcohol were 9.87×10^-3, 8.91×10^-3 and 6.11×10^-3 mN/m respectively, and the best salt concentration were 15.0%, 12.5% and 6.5% of NaCl, so they were suitable for oil fields with high mineralization degree. After adding isoamyl alcohol as co-surfactant, the equilibrium interfacial tension would be reduced. Now, the minimum equilibrium interfacial tension of NPPS-3, NPPS-6 and NPPS-9 were 3.69×10^-3, 3.98×10^-3 and 2.30×10^-3 mN/m respectively, while the best salt concentration were 11.0%, 5.5% and 3.5% of NaCl. Therefore, they were also suitable for oil fields with high mineralization degree under this condition.The experimental results show that the different saltilty under which equilibrium interfacial tension can achieve ultralow could be satisfied by adding isoamyl alcohol and adjusting PPO chain length. There is another feature, these extended anionic surfactant could be used in a wide range of concentrations. Under the conditions that isoamyl alcohol was 0.9% (V/V) and the content of NaCl was in optimized conditions, when the surfactant concentrations ranged from 0.1% to 0.3% (W/W), all these three extended anionic surfactants could reduce the oil-water interfacial tension to preferred ultralow values.