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A new calculation approach for predicting hydrogen hydrate equilibrium is described by using the concept of a single hydrogen cluster in one cavity. By integrating ab initio calculations with classical statistical thermodynamics, this approach enables van der Waals model to predict the dissociation pressure of hydrogen hydrates.

A new thermodynamic calculation procedure utilizing an excess Gibbs potential is described to predict the equilibrium conditions of multicomponent gas hydrates containing hydrogen. The model prediction is good for the ternary and quaternary mixture hydrates, but its error has increased with increasing pressure and temperature under the presence of THF (tetra-hydrofuran).

Trapping CO2in hydrates is one of the new technologies for CO2capture and storage. One of the primary obstacles to this option is the low formation rate. This work presents the rapid formation of CO2hydrates with a small amount of cyclopentane (CP). The formation kinetics was investigated in a 474 cm3nonstirred batch reactor with 100 and 200 cm3of water. At volume ratios of CP to water between 0.01 and 0.1, the maximum growth rate is 0.32 mol h−1at CO2pressures ranging from 1.9 to 3.4 MPa and at 274 K. CO2hydrates (sI) and CO2+ CP (sII) binary hydrates coexist at the end of hydrate growth. The mole ratio of CO2entrapped in the sI hydrates to that in the sII binary hydrates is higher with 100 cm3of water than with 200 cm3of water. The same trend is also observed for the total amount of CO2entrapped in the hydrate phase. The growth rate depends not only on the water volume but also on the pressure. The hydrate growth rate and the water conversion reach a maximum at 3.06 MPa and then decrease as the pressure increases from 1.9 to 3.4 MPa with 100 cm3of water and 5 cm3of CP. The water conversion to the hydrates reaches 52% within 2 h. This accelerated formation kinetics can provide a stepping-stone for developing a new hydrate-based CO2capture and storage technique. [ABSTRACT FROM AUTHOR]

This work addresses a new method for estimating the liquid still composition trajectory of batch reactive distillation systems based on material balance and reaction equilibrium data. The still trajectory information is essential to determining whether pure products are reachable from this still pot trajectory when several distillation boundaries are present, initial feed compositions can vary, and the number of components exceeds our visualization capability. For a given feed to product flow ratio with constant feed charge and product compositions, the still pot composition trajectory is mathematically confined to the intersection between the reaction equilibrium manifold and a “material balance plane” that is the union of stoichiometric lines and material balance rays connecting still and product compositions. Starting from this estimated still pot trajectory, we can easily extend feasibility studies of various batch reactive distillation configurations even for multireaction systems. [ABSTRACT FROM AUTHOR]

Cyclopentane (CP) forms sII hydrates, in which CP only occupies the large cavities. Small gas molecules such as hydrogen and carbon dioxide can be encaged in the small cavities. However, there are no reported data on the equilibrium conditions of CP + H2and CP + CO2binary hydrates, which are essential to developing CO2capturing or H2enriching processes. In this study, the dissociation temperature of CP + H2hydrate pressures ranging from (2.7 to 11.1) MPa and CP + CO2hydrates at pressures of (0.89 to 3.51) MPa was measured by using a high-pressure MicroDSC. [ABSTRACT FROM AUTHOR]