Spontaneous Lifting and Self-Cleaning of Gas Hydrate Crystals.

Abstract

Crystal fouling, which refers to the accumulation of precipitates on surfaces and the associated damage, is a common problem in many industrial processes. In deepwater oil and gas transportation, hydrate blockage poses as a considerable barrier. Consequently, modifying hydrophobicity of surfaces has become an increasingly focused strategy to mitigate hydrate. However, the design of surfaces that effectively control the hydrate remains challenging. Herein, we report a superior smooth anti-hydrate material based on silanized modification. The low-adhesion silanized silicon wafer (SSW) realizes a win-win strategy of hard formation and easy removal. Through a comprehensive study combining experimental validation with theoretical analysis, the unique characteristics of SSW in the field of anti-hydrate surfaces were deeply discussed. Various hydrate crystals exhibited a completely different hydrate growth mode at the SSW surface, in which hydrate crystals spontaneously elevated and lifted themselves off from the surface. The presence of the fluorine element on the SSW surface allowed self-lifting growth of hydrate crystals after they covered the water droplet. And the loose and porous crystal structure in this self-lifting growth could reduce the contact area between the hydrate crystals and the substrate, allowing the crystals with minimal adhesion force and removal disturbance. Furthermore, the gas enrichment on the SSW surface also reduced the contact with the substrate, thereby decreasing the adhesion and allowing self-cleaning behavior. These results indicate that the silanized surface is a promising candidate for developing anti-hydrate materials for hydrocarbon production and transportation industry.