Instant Conversion of Air to a Clathrate Hydrate: CO2 Hydrates Directly from Moist Air and Moist CO2(g)

The rapid conversion of vapor mixtures containing the gases CO2, H2S, and HCN to clathrate hydrates was reported recently. The novel method is based on the pulsing of warm vapor mixtures, including a carrier gas, into a cold condensation chamber. With cooling, the vapors, which also include similar to 1% water and either tetrahydrofuran or trimethylene oxide as a catalyst, nucleate aqueous solution nanodroplets that, on a millisecond time scale, crystallize as hydrate nanoparticles that consume 100% of the water. Humid air approximates the content of mixtures used successfully in the vapor-to-hydrate conversions. FTIR spectra are examined for gas hydrates formed directly from air and air enriched with CO2, as well as hydrate particles for which CO2(g) serves as both guest and aerosol medium. In each instance all of the water in the condensed phase converts to a clathrate hydrate. The subsecond ether-catalyzed formation of the hydrates near 230 K requires only a few percent of the CO2 pressure used in conventional processes that yield fractional amounts of gas hydrates on an hour time scale in the same temperature range.