Experimental study on in situ dissociation kinetics of CO2 hydrate in pure water and water/sediments systems

Recently, hydrate technology as a newly emerging field has been attracting more and more attention. To support its potential applications, the dissociation behaviors and kinetics of CO2 hydrate in pure water and water/sediments systems at specified temperatures were studied experimentally by depressurization method. This work reveals two novel aspects of CO2 hydrate dissociation. Firstly, it is remarkable that the dissociation rate of CO2 hydrate in water/sediments is faster than that of CO2 hydrate in pure water, which has not been conscious previously. Secondly, a pseudo first‐order kinetic equation including the kinetic constant and activation energy was formulated to describe the dissociation process. Temperature plays an important role and the dissociation rate constant (kd) and activation energy (ΔEa) were obtained through the dissociation experiments at different temperatures. For CO2 hydrate in pure water, the dissociation rate constant increased from 0.02 to 0.13 mol/(dm2⋅MPa⋅min) at the temperature from 273.86 to 276.11 K, and the activation energy was 469.06 kJ mol−1. For CO2 hydrate in water/sediments, the dissociation rate constant was from 0.03 to 0.15 mol/(dm2⋅MPa⋅min) at the temperature ranging from 273.45 to 276.11 K, and the activation energy was 346.30 kJ mol−1. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.