Experimental evidence on the prolonged stability of CO2 hydrates in the self-preservation region

Most chemical engineering firms value carbon dioxide as a valuable commodity and the main greenhouse gas that is alarming climate change. The importance of limiting CO2 emissions while also providing sectors with beneficial CO2 is paramount. The current work defines the viability of CO2 capture via gas hydrates, followed by storage and transportation. 0.5 wt% of l-methionine amino acid powder is used as an additive. The experiments were performed in non-stir conditions, and the CO2 hydrate nucleation was observed at 268.3 ± 2.2 K and 2370.7 ± 56.2 kPa. l-methionine accelerated the gas uptake kinetics, and 90% of the hydrate conversion was within 28.7 ± 4.6 minutes, which is 6.25 times faster than the bulk system (without additive). It acted as a catalyst and did not alter the hydrate's structural characteristics. The stochastic nature of hydrate nucleation is abated, and water reuse yielded a similar conversion. The maximum achieved CO2 hydrate yield is 100.3 ± 1.5 v/v, accounting for ∼67% of the maximum feasible value (149.3 v/v). For viable transportation of the captured CO2 in hydrate form, the self-preservation phenomenon is experimentally evaluated at ∼268 K. The study established the prolonged stability of CO2 hydrates in the self-preservation zone for 50 hours. The hydrate preservation is interrelated to the ice capping theory, which describes how a thin layer of liquid water forms on the surface of the hydrate and eventually freezes to form the ice cap. The boil-off observed due to the hydrate melting, and self-annealing was 25% of the total gas. Regasification is easy and accomplished by raising the temperature over the ice melting point. The findings highlight the significance of more extended hydrate stability in the self-preservation window, which could be a valuable tool for CO2 storage and transportation under milder pressure-temperature conditions.