The synthesis, characterization, surface activity and potential applications of ethoxylated surfactants derived from low-value refinery feedstocks, a propane-precipitated asphaltene stream (PDA), catalytic cracked tars and petroleum tars, are presented. The new tensoactive compounds were synthesized by an alkali-catalyzed ethoxylation reaction (135–150°C, 20–60psi) and were characterized by molecular weight determinations, elemental analysis, FT-IR, and 1H NMR. Several novel surfactants were prepared with different ethylene oxide/hydrocarbon molar ratios (from 2 up to 50) for each refinery stream. The interfacial properties were studied using a toluene/water model system and a minimum value of interfacial tension (0.01dyn/cm) was obtained for a 12-ethoxylated PDA tensoactive compound. The results indicated that the new surfactants have potential applications for enhanced oil recovery (crude oil/formation water interfacial tension of approximately 0.1dyn/cm) and as stabilizing agents for crude oil-in-water emulsions (minimum mean droplet size of 36μm).

Acid, basic and neutral fractions from Orinoco Belt Crude Oil (Cerro Negro) were isolated by ion-exchange chromatography and characterized by spectroscopic methods (FTIR, H- and 13C-NMR), titration with KOH and molecular weight measurements using vapor pressure osmometry (VPO). For the evaluation of the interfacial tension, a toluene/water model system was used. In general, it was determined that interfacially active compounds (natural surfactants) at high pH values are concentrated mainly in the acid fractions, strong acid fraction (SAF) and total acid fraction (TAF) of the crude oil. By interfacial tensions determinations, it was concluded that the hydrophobic portion of the natural surfactants has higher aromatic character and molecular weight whereas the hydrophilic region showed higher acidity and concentration of polar sustituents in comparison with the original Cerro Negro crude oil. Also it was found that SAF has lower interfacial activity per molecule than TAF. The results were explained in terms of a better hydrophilic-lipophilic balance of the TAF, (higher molecular weight, lower concentration of polar groups and higher total acid number) in comparison with the SAF. Finally, it was determined that Cerro Negro crude oil and its components suffer important changes (decarboxylation reactions, etc.) at temperatures normally reached during distillation (> 250°C), therefore, their interfacial activities are also substantially changed as well.

The synthesis of new water soluble nonylphenol poly(ethylene carbonate) surfactants derived from nonylphenol ethoxylated (NP(EO)(10)), ethylene oxide (EO), and carbon dioxide was carried out in high yields in the presence of K2SnO3 as a basic catalysts. Synthesis reactions were carried out in a stainless-steel reactor at 175 degrees C at an initial pressure of 800 psi for a 24 h-period. Surfactants were characterized by FTIR, H-1- and C-13-NMR. The percentages of carbon dioxide incorporation obtained were between 5.8 and 10.9, depending on the starting molar ratio of NP(EO)(10):EO:CO2. CMC values, as well as cloud points decreased with the molar ratio CO2/EO, indicating a reduction of hydrophilic character of the surfactants due to the addition of carbonate groups, O-C(=O)-O, into the ethoxylated chains. Also, the area per molecule at the interface increased when molar ratio CO2/EO increased, indicating a two site anchoring model for both hydrophobic moieties, poly(ethylene carbonate) chain and nonylphenol. Finally, nonylphenol poly(ethylene carbonate) surfactants showed good emulsification properties for stabilizing sunflower oil in water emulsions.