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Alkyl polyoxyethylene ethers are a new type of surfactant that maintains good fluidity even at low temperatures. They can also be used in combination with various other surfactants and additives, thereby reducing the amount of these additives needed and achieving a good cost-performance ratio. The method used for the industrial production of secondary alcohols is typically the oxidation of n-paraffin borate, but it has the problems of a long process and complex reactions. The process involving paraffin cracking and the hydration of high-carbon alkenes features a shorter process and higher product quality, yet it also suffers from the difficulty of carrying out the hydration of high-carbon alkenes. Production of higher carbon alcohols: Multiple routes for different products. Higher carbon alcohols refer to mixtures of monohydric alcohols with 6 or more carbon atoms; they are primarily used to produce various esters that serve as plasticizers for polymers or as components in detergents. Based on the type of carbon atom to which the hydroxyl group is attached, they can be classified as primary alcohols, secondary alcohols, and tertiary alcohols. There are several process routes for producing higher carbon alcohols. The first is the hydrogenation of natural animal and plant fats, yielding straight-chain primary alcohols with an even number of carbon atoms. The second is the Ziegler method, which also produces straight-chain primary alcohols with an even number of carbon atoms. The third is the carbonyl synthesis method, resulting in straight-chain primary alcohols with both odd and even numbers of carbon atoms. The fourth is the hydrogenation of synthetic fatty acids, giving rise to mixed straight-chain primary alcohols with both odd and even numbers of carbon atoms. The fifth is the oxidation of paraffins, which produces secondary alcohols. Paraffin oxidation: A long process with complex reactions. The liquid-phase oxidation of paraffin n-alkanes to secondary alcohols is a patented technology developed by BASF in 1913. Building on this foundation, the former Soviet Union constructed a plant with an annual production capacity of 10,000 tons in April 1959, and another plant with an annual capacity of 100,000 tons in 1968. Since then, products have been released in both the United States and Japan. This production process is completely continuous: n-paraffin is oxidized in the presence of boric acid, the unreacted paraffin is recovered from the oxidation reaction mixture, and then the purification of the secondary alcohol is achieved through the hydrolysis of the borate ester in the secondary alcohol. In this process, boric acid is used as a catalyst to convert alcohols into borate esters and to facilitate the selective decomposition of the intermediate peroxides back into alcohols; the unreacted n-paraffins are then recovered through the flashing of the oxidized reaction mixture. The borate ester in the distillate at the bottom of the distillation tower is hydrolyzed to yield crude alcohol and an aqueous boric acid solution; boric acid is recovered as a solid through continuous crystallization, and after dehydration it is returned for reuse in oxidation processes. The oil layer containing the crude alcohol is saponified with a base; after the removal of by-products, it is processed in a cutting tower to yield purified secondary alcohol. Aromatics in paraffin inhibit the oxidation of n-alkanes; the lower the aromatic content, the higher the conversion rate of n-alkanes and the greater the selectivity for secondary alcohols. Therefore, as much of the aromatic components as possible should be removed during production. The use of a hydrodearomatization process allows the naphthenes produced by the hydrogenation of aromatics to remain in the oxidation feedstock; during the oxidation process, naphthenic acids with distinctive odors may be formed, affecting the quality of the secondary alcohol product. The entire process of oxidizing paraffin to secondary alcohols is long and involves multiple steps, all of which take place in the liquid phase. The purity of the resulting product is relatively low, as it also contains small amounts of alkanes, diols, acids, and other impurities. Paraffin cracking – olefin hydration: Short process with high product quality. The hydration of high-carbon olefins is also one of the methods for producing secondary alcohols. Currently, high-carbon olefins are in short supply in the domestic market; paraffin cracking can be used to produce high-carbon olefins, thereby enabling the use of a paraffin cracking–olefin hydration route for the production of secondary alcohols. The selective direct hydration of olefins to secondary alcohols involves a short process, resulting in secondary alcohols of high quality. The hydration method using sulfuric acid and silica gel as a catalyst is suitable for the hydration of C2–C9 olefins. This reaction can be carried out at atmospheric pressure or under pressure; a fixed bed can be used, or the catalyst can be suspended in a non-aqueous solution. The key issue is the preparation of the catalyst. The hydrolysis method using organic phase salts as catalysts can directly hydrolyze C2–C30 alkenes to secondary alcohols. The catalyst used is hexavalent molybdenum, including molybdates and various organic molybdenum acids. This catalyst does not destroy the structure of the olefins in hydration reactions, nor does it break the existing substituents on the molecules. This is also what distinguishes it from other inorganic acid catalysts. The method of addition of olefins to hydrogen chloride followed by hydrolysis can also be employed; first, the olefin is catalytically added to hydrogen chloride to yield 2-chloroalkanes, which are then hydrolyzed to produce secondary alcohols. Among them, the addition reaction of olefins with hydrogen chloride proceeds relatively easily. An organic inert liquid with a dielectric constant greater than 20 is used as a diluent to dissolve the catalyst Lewis acid in it. Diluents can include nitromethane, nitroethane, dimethyl sulfoxide, sulfolane, etc., while the Lewis acids used as catalysts are zinc dichloride, iron trichloride, titanium tetrachloride, etc. The reaction is carried out at atmospheric pressure and under anhydrous conditions. Before adding the olefin, introducing hydrogen chloride gas can promote the dissolution of the catalyst in the diluent. Since the diluent is insoluble in chloroalkanes, it is easy to separate the chloroalkanes. The upper layer of the reaction mixture is the chloroalkane, while the lower layer consists of the catalyst and solvent. The product is washed with water from the top until it reaches neutrality, and then dried over sodium sulfate to yield a fairly pure final product. However, the hydration of low-carbon olefins is easy to achieve, while the hydration of high-carbon olefins is difficult to complete. This is because the higher the carbon count, the lower the miscibility of the olefin with water, making it difficult for a reaction to occur; simultaneously, longer chains are more prone to breaking, resulting in a low conversion rate.