Linear alcohol ethoxysulfates

Surfactants evaluated in surfactant-enhanced alkaline flooding include internal olefin sulfonates (259,261), linear alkyl xylene sulfonates (262), petroleum sulfonates (262), alcohol ethoxysulfates (258,261,263), and alcohol ethoxylates/anionic surfactants (257). Water-thickening polymers, either xanthan or polyacrylamide, can reduce injected fluid mobiHty in alkaline flooding (264) and surfactant-enhanced alkaline flooding (259,263). The combined use of alkah, surfactant, and water-thickening polymer has been termed the alkaH—surfactant—polymer (ASP) process. Cross-linked polymers have been used to increase volumetric sweep efficiency of surfactant—polymer—alkaline agent formulations (265). 

Both nonionic and anionic surfactants have been evaluated in this application (488,489) including internal olefin sulfonates (487, 490), linear alkylxylene sulfonates (490), petroleum sulfonates (491), alcohol ethoxysulfates (487,489,492). Ethoxylated alcohols have been added to some anionic surfactant formulations to improve interfacial properties (486). The use of water thickening polymers, either xanthan or polyacrylamide to reduce injected fluid mobility mobility has been proposed for both alkaline flooding (493) and surfactant enhanced alkaline flooding (492). Crosslinked polymers have been used to increase volumetric sweep efficiency of surfactant - polymer - alkaline agent formulations (493). 

Alcohol ethoxysulfates (AES) are made by reaction of 3-7 mol of ethylene oxide with a linear C12-C14 primary alcohol to give a low molecular weight ethoxylate, followed by the usual sulfonation. 

The shift to oleochemicals has been supported by increasing environmental concerns and a preference by some consumers, especially in Europe, for materials based on natural or renewable resources. Although linear alkylbenzenesulfonates (LASs) are petrochemically based, alcohol ethoxylates, alcohol ethoxysulfates, and primary alcohol sulfates are derived from long-chain alcohols that can be either petrochemically or oleochemically sourced. There has been debate over the relative advantages of natural (oleochemical) vs synthetic (petrochemical) based surfactants. However, detailed analyses have shown there is litde objective benefit for one over the other. 

Amnionic surfactants used in shampoos, cosmetics, toothpaste, and laundry products include linear alkylbenzenesulfonates (LAS), alcohol sulfates (AS), alcohol ethoxysulfates (AES), alcohol glycerol ether sulfonates, and alpha-olefin sulfates. Household end use of anionic surfactants in the United States was 7.3 X 105 metric tons in 1987 LAS, AS, and AES accounted for 98% of the total (I). 

Alcohols in the range C12—Ci8 are important raw materials for the production of a key group of surfactants ethoxylates, sulfates and ethoxysulfates among others. Alcohols used in the surfactant industry are primary, linear, or with different degrees of branching, and they can be produced from either petrochemical sources (ethylene or linear paraffins) or from oleochemical products (animal fats and vegetable oils). 

If an anionic surfactant is heated anaerobically to 650 C, characteristic fragments are produced. In the case of LAS, the pyrolysis products are linear C2-C10 olefins and paraffins, benzene, toluene, and xylenes. For alcohol sulfates and ethoxysulfates, C5-C14 a-olefins are found, as well as the original alcohols. Paraffin sulfonates give primarily C5-C17 a-olefins (11). This approach can also be used for quantitative analysis, measuring either the hydrocarbon fragments or the SO2 evolved. Addition of carbohydrazide to the sample gives more complete yield of hydrocarbons (12). 

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