CO2 capture through gas hydrate formation in the presence of polyethyleneimine-surface-grafted clay

Abstract

CO2 capture through gas hydrate formation was performed using a stirring-type vessel in the presence of nanoclay and polyethyleneimine-grafted nanoclay. First, the grafting process was implemented via the wet impregnation method. The nanoparticles were characterized using FT-IR, FESEM, EDS, BET, XRD, TGA, Zeta potential, and DLS analyses. The characterization analyses confirmed surface-grafting of the nanoclay. Then, the hydrate formation experiments were implemented at three various nanoparticle loadings (200, 400, and 500 ppm). Water-to-hydrate conversion, CO2 gas consumption, apparent rate constant, and hydrate storage capacity were obtained and compared. Prior to conducting the CO2 hydrate formation experiments in the presence of nanoparticles, the rocking-type and stirring-type vessels were compared to evaluate the hydrate formation rate (using pure water). Stirring-type vessel exhibited higher hydrate formation rates than rocking-type vessel along with improved gas storage performance which resulted in a 22.4% increase in CO2 consumption. Thus, the effect of additives was examined using the stirring-type vessel. Surface-grafted nanoclay led to higher CO2 consumption compared to nanoclay at all concentrations. Using 500 ppm of modified nanoclay, grafted by 50 mass% polyethyleneimine (PEI) solution as additive, the maximum enhancement of CO2 consumption in the hydrate phase in comparison with pure water was obtained, along with the greatest water to hydrate conversion value (39.67). This study introduces a new technique by modifying nanoclay with PEI to improve CO2 storage in gas hydrate phase, presenting potential advancements in gas storage technology.