Kinetics investigation of CH4 hydrates formation in the silicon carbide foam ceramics

Hydrate-based solidification of CH₄ storage and transportation is a potential technology which will be utilized in the separation of coal-bed gas, natural gas and biomass gas. Chemical additives and porous materials are usually used for accelerating the CH₄ hydrate formation and increasing the CH₄ capacity. Here, the silicon carbide foam ceramics (SFC) as a porous medium in combination with tetrabutylphosphonium bromide ([P_{4 4 4 4}]Br) and 1,3-dioxolane as chemical promoters were used to influence CH₄ hydrate formation and decomposition properties. The experimental results show that the presence of SFC leads to shortened induction time of CH₄ hydrate nucleation by 15 ∼ 25 % and increased gas storage capacity by 30 ∼ 40 % compared to that in pure water. Adding [P_{4 4 4 4}]Br reduces the induction time by only 3 %–10 % while increases gas capacity by nearly 30 %. In contrast, the 1,3-dioxlane demonstrates superior effectiveness in promoting CH₄ hydrate growth with induction time shortened by 40 %–60 %. Compared to pure water systems, SFC + 1,3-dioxolane may enhance the gas capacity of around 80 %. In terms of dissociation process, CH₄ hydrate formed in the SFC have lower dissociation temperature and shorter pre-dissociation time, indicating that hydrate formed in the porous space is easy to decompose. Moreover, after adding 1,3-dioxolane, the decomposition time was shortened further. However, 30PPI SFC is optimal for its higher dissociation temperature and longer pre-dissociation time.