Hydrophobic association water-soluble xanthan gum and preparation method and application thereof

Abstract

The invention discloses a hydrophobic association water-soluble xanthan gum and a preparation method and an application thereof. According to the modified xanthan gum, DMF is adopted as a reaction medium and octadecyl isocyanate is adopted as a modifier; the isocyanate group in octadecyl isocyanate reacts with the hydroxyl group (-OH) in xanthan gum molecules so that a long alkyl chain is introduced into xanthan gum molecules, thus obtaining the hydrophobic association water-soluble xanthan gum with surface activity and bactericidal property. The method has the advantages of mild reaction conditions, use of easily available raw materials, high reactant conversion rate, and convenient product post-treatment. The hydrophobic association water-soluble xanthan gum has better temperature resistance, better salt resistance, better aging resistance and lower surface tension. With the relatively low surface tension, stratum surface wettability can be changed, dispersion of crude oil in water can be enhanced, and the rheological property of crude oil is changed.

Description

technical field [0001] The invention belongs to the technical field of polymer chemistry and polymer modification, and relates to a hydrophobic association type water-soluble xanthan gum and a preparation method and application thereof. Background technique [0002] Xanthan gum is a high-viscosity water-soluble microbial exopolysaccharide produced by Xanthomonas campestris with carbohydrates as the main raw material through aerobic fermentation bioengineering technology. Xanthan gum is an important high molecular polysaccharide polymer, its molecular weight is as high as 2×10 6- 50×10 6 g / mol. [0003] Xanthan gum is connected by D-glucose through β-1,4-glucosidic bonds to form a main chain, and every two glucose residues on the main chain are connected with a branch chain formed by three sugar molecules of mannose, glucuronic acid and mannose . The two mannose molecules attached to the branch chain are respectively acetylated or acetoylated. The skeleton structure of x...

AI Technical Summary

Problems solved by technology

[0004] Although xanthan gum has the above advantages, it will be thermally oxidatively degraded in high-temperature formations. The formation temperature used for tertiary oil recovery should generally not be higher than 60°C. The viscosity of the solution will decrease significantly with the increase of temperature. Decomposition, when the solution is stored for more than one day, it is necessary to add preservatives

Xie Jun et al., Mineral Rock, 2003, 23(2): 103-107, studied the influence of temperature on the viscosity of xanthan gum solution with a concentration of 1000mg / L, and found that the viscosity of xanthan gum solution decreased with the increase of temperature The trend is obvious, when the temperature rises from 30°C to 87°C, the viscosity of the xanthan gum solution drops from 34.5mPa.s to 9.5mPas, and the viscosity retention rate is 27.5%; / L of xanthan gum solution (without deoxygenation) placed in an incubator at 87°C for 90 days, the viscosity retention rate has dropped from 100% to 28.4%, which shows that the thermal stability of xanthan gum solution at high temperature is relatively low. Difference

Chinese patent document CN102134283A discloses a method for preparing associative modified xanthan gum. Although this technology is prepared by alkali-catalyzed etherification, the obtained associative xanthan gum shows good thermal degradation resistance and is used for oil recovery. After 90 days of high-temperature aging in the formation, the viscosity dropped from the original 340mPa.s to 156mPas, and the viscosity retention rate was as high as 45.9%, but its modifier was a chlorinated hydrocarbon (benzyl chloride) containing a benzene ring. The product is easy to cause great pollution to the environment

CN103724443A discloses the method for preparing long-chain alkyl modified xanthan gum by carrying out etherification reaction in the emulsion system, the degree of substitution is improved, but the reaction yield and molecular weight all need to be improved

Images