Methane and carbon dioxide hydrates properties in presence of Inconel 718 particles: Analyses on its potential application in gas separation processes to perform efficiency improvement

Methane and carbon dioxide hydrates were formed in a small-scale experimental apparatus and in presence of a pure-quartz porous sediment impregnated with Inconel 718 particles produced via gas atomization and destined to additive manufacturing applications. The aim of this work consisted in exploring for the first time the effect of such material, commonly used in additive manufacturing, for gas hydrates production, in order to detect its properties in this field and its potential applications. Three In concentrations were tested: 8.68, 17.36 and 26.04 wt%. Multiple tests were carried out for both the guest compounds considered. This compound was found to act as promoter for the process in presence of methane and inhibitor in presence of carbon dioxide. In particular, at temperatures ranging from 2.1° to 6.5 °C and with 26.04 wt% In, CO2 molecules required higher pressure than CH4 molecules for being trapped into water cages. Because CO2 hydrates naturally form at milder thermodynamic conditions than CH4 hydrates, the existence of a narrow thermodynamic region, with this reverse property, was highlighted for being suitably exploited to improve the efficiency of CO2/CH4 mixture separation via hydrates formation.