Physicochemical Features of Methane Hydrate Formation within a Hybrid Cellulose-Based Material

Abstract

The development of advanced porous matrices that promote efficient and reversible gas hydrate formation is critical for applications in energy storage and gas transportation. This study investigates the physicochemical characteristics of methane hydrate formation within hybrid cellulose-based fibers, presenting a comparative analysis of carboxylated nanofibrillar cellulose (CNC) and the CNC grafted with polyacrylonitrile chains (CNC-g-PAN). The properties of cellulose-based hydrate carriers were characterized using FT‑IR spectroscopy and thermogravimetric analysis. The materials were tested with water contents of 45 and 60 wt % (CNC45, CNC60, CNC-g-PAN45, and CNC-g-PAN60) under a constant initial pressure of 10.3 MPa, undergoing temperature cycling between 25°C and target formation temperatures of 0.9°C or ‒3°C. Results demonstrate that the grafting modification significantly enhances hydrate formation capacity. While the water-to-hydrate conversion for CNC45 and CNC60 was 63% and 35% respectively at 0.9°C, grafting polyacrylonitrile increased these values to 78 and 58% under identical conditions. This marked improvement, attributed to the modified surface properties of the hybrid material, underscores its potential as an effective medium for the cyclic production and decomposition of gas hydrates. The findings provide valuable physicochemical insights for designing next-generation hydrate carriers, with direct implications for technologies in gas sequestration and thermal energy storage.