Synthesis of Alkylbenzene from Medium-Chain Olefins Catalyzed by an Acidic Ionic Liquid and the Surface Properties of Their Sulfonate

The Fischer-Tropsch synthesis can be used to achieve a high content of α-olefin (C5–C11) products using Fe-based catalysts. Herein, C6 and C8 α-olefins have been selected as examples for the alkylation of benzene catalyzed by using an acidic ionic liquid (Et3NHCl-AlCl3) to obtain a variety of intermediates used to prepare surfactants. A series of alkylbenzenes were synthesized by controlling the reaction conditions and their corresponding alkylbenzene sulfonates were successfully obtained by sulfonation and neutralization. It was found that the single chain alkylbenzene sulfonate derivatives did not display typical surfactant properties due to their short hydrophobic chain length. However, double chain alkylbenzene sulfonates exhibit excellent surfactant properties, and decrease the water surface tension compared to commercially available sodium dodecylbenzene sulfonates. A γ cmc (mN m−1) value of 32.70 was observed for sodium di-hexylbenzene sulfonates, 29.98 for sodium di-octylbenzene sulfonates, and 36.0 for sodium dodecylbenzene sulfonates. In addition, double chain alkylbenzene sulfonates show an improved emulsifying and wettability performance compared to sodium dodecylbenzene sulfonate. This demonstrates that the capability of alkylbenzene sulfonate to decrease the surface tension are closely related to the total carbon number of side chain-alkyl groups connected to the benzene ring.

Pseudo-Gemini Biosurfactants with CO2 Switchability for Enhanced Oil Recovery (EOR)

Novel biosurfactants with high performance are always needed in the petroleum industry for environmental sustainability. Herein, we developed a series of biosurfactants to enhance the heavy oil recovery from Canadian oil sands. Pseudo-Gemini biosurfactants were designed to be interfacially active and CO2 switchable. The strong interfacial activity of biosurfactants promotes the liberation of heavy oil from solid substrates, which was demonstrated by the liberation visualization cell. On the other hand, the separation of heavy oil from extraction fluid was also facilitated by activating the CO2 switchability of biosurfactants. Since the efficiencies in both the heavy oil liberation and the oil-water separation were improved, the total heavy oil recovery could be significantly enhanced. Therefore, these biosurfactants are believed to be promising in the application of enhanced oil recovery from oil sands ore.

Synthesis and Interfacial Tensions of Sodium p-Dimethyl Dodecylbenzene Sulfonates

Six isomers of sodium para-dimethyl dodecylbenzene sulfonates (p-S12) were synthesized by a series of reactions. The surface tension of the isomers p-S12 in an aqueous NaCl solution (4000 mg/L) was measured. From the data the following parameters were calculated: critical micelle concentration (CMC), the surface tension at the CMC (γ CMC ), the surface excess concentration at surface saturation (Γ max) and the area per molecule at surface saturation (A s min). The A s min increased and the Γ max decreased when the aromatic nucleus moves to the center of long-chain alkyl group. The dynamic interfacial tensions (DIFT) between p-S12 in 4000 mg/L NaCl aqueous solution and five n-paraffins were measured by using a spinning drop technique. The DIFT of the p-S12 showed the characteristic that the interfacial tension (IFT) is low at the beginning, then increases, reaches a maximum value, and finally continues to decrease until it reaches a stable value. By the measurement of alkane carbon number for the minimum IFT, n min, of the six isomers solutions, we found that the n min firstly decreases and then increases when the aromatic nucleus moves to the long-chain alkyl group. This phenomenon is due to the differences of hydrophilic-lipophilic properties and the structure of the p-S12 isomers.

Ultra-Low Interfacial Tension of a Surfactant under a Wide Range of Temperature and Salinity Conditions for Chemical Enhanced Oil Recovery

Ultra-low interfacial tension (IFT) is an important parameter for selecting surfactants to apply in chemical enhanced oil recovery (CEOR). In this study, the IFT between the solution of the surfactant ANSM and Dagang crude oil was measured using the spinning drop method. The effects of the surfactant concentration, temperature, salt types and aging time on the IFT were investigated in detail. The results showed that ANSM effectively reduced the IFT without alkali. Ultra-low IFT was formed in a wide range of surfactant concentrations from 0.05∼ 0.5 wt.% and a wide range of temperatures from 20∼80°C. In addition, ANSM also showed great NaCl tolerance, with a maximum NaCl concentration of 130000 mg · L−1. Furthermore, 0.1 wt.% ANSM maintained an ultra-low IFT, even with 900 mg · L−1 CaCl2 or 1300 mg · L−1 MgCl2, in the presence of 10000 mg · L−1 NaCl. ANSM also had an excellent stability; the solution maintained the ultra-low IFT for 60 days at 90°C. Thus, ANSM proved itself as a potential candidate for CEOR.

Biodegradable Polyoxyethylenated Pentaerythritol Quaternary Esters as Oil Spill Dispersants

Four polyoxyethylenated pentaerythritol (PE) ester surfactants have been synthesized. The molecular weights of these surfactants were calculated and evaluated experimentally by GPC and confirmed by calculations based on 1H-NMR. Also, their HLB values were calculated by Griffin formula. The surface tension and thermodynamic properties of the surfactants were obtained from surface tension measurements at different temperatures (298 – 318 K). It was found that the minimum area/surfactant molecule (Amin) for the investigated surfactants increased with increasing the molecular weight of the incorporated ethylene oxide. The thermodynamic parameters of micellization (ΔGmic, ΔHmic and ΔSmic) and that for adsorption (ΔGad, ΔHad and ΔSad) were also calculated. The more negative Gibbs free energy of adsorption values than those of micellization suggest that these surfactants favor adsorption than micellization. This finding is utilized for monitoring their dispersancy power. It was found that the water solubility of the prepared surfactants is correlated to their HLB values. Furthermore, the biodegradability of the prepared compounds was studied at different conditions in order to investigate their usability as oil spill dispersants. The data revealed that PE200-C12 had maximum dispersion efficiency and it was completely biodegraded after 8 days.