Hydroquinone clathrates and the theory of clathrate formation

Revisiting the thermodynamic modelling of type I gas–hydroquinone clathrates

“…For type I HQ clathrates, considering that Dm ab 0 , DH ab 0 and DV ab 0 are the same, whatever the guest, as the b-HQ structure is the same for all the guests, the only leverage in the theory to obtain an occupancy function of the guest is to include the influence of guest-guest interactions. Belosludov and co-workers [42][43][44][45] studied the importance of these interactions in the clathrate equilibrium. They have shown that in HQ clathrates (especially at high temperature) the guest-guest interaction is weaker than in other clathrates since the cages are relatively small and the volume of the cages is a small part of the whole crystal volume but that, even in these systems, the guest-guest interaction is rather clearly revealed.…”

“…The second group of modifications is not focused solely on hydrates but concerns all types of clathrate compounds. It was performed by Belosludov and coworkers who proposed a non-ideal version of vdWP theory essentially by including: (i) guest-guest interactions to take into account the cooperative behaviour of the guests that participate in the stabilization of the structure [41][42][43] and (ii) the possibility of the a-HQ phase to dissolve guests. 44,45 These improvements, contrary to what has been done in the case of hydrate modelling during the last few decades, have not been widely compared to experimental results of the authors.…”

Kinetics of CO2 Capture by Hydroquinone Clathrates

“…In the same way as water can form hydrates in the presence of certain gases, hydroquinone (HQ) is also known to form organic clathrates with various gaseous species (e.g., CO 2 , H 2 S, CO, and SO 2 ) in well-specified thermodynamic conditions of pressure and temperature . These gases are retained in a network of self-associating molecules of HQ forming cavities, with an ideal stoichiometry corresponding to the ratio 3:1 (i.e., three molecules of HQ per guest molecule). , The HQ clathrates (β-HQ) are characterized by an occupancy factor (called clathrate occupancy), which is the proportion of cavities filled by guest molecules, ranging from 0 for guest-free clathrates to 1 for full clathrates. , The formation of HQ clathrates is achieved in a two-step reaction, in which the native HQ (α-HQ) is put in contact with suitable guest molecules. , The gas molecules are first included in the cavities of α-HQ (in a phenomenon called “gas solubilization in the HQ α-form”). , Then after an induction period (corresponding to the time during which the α-HQ starts to transform into clathrates), the α/β phase transition takes place and the β-HQ is gradually filled.…”

“…16,17 The gas molecules are first included in the cavities of α-HQ (in a phenomenon called "gas solubilization in the HQ αform"). 18,19 Then after an induction period (corresponding to the time during which the α-HQ starts to transform into clathrates), the α/β phase transition takes place and the β-HQ is gradually filled.…”

Calorimetric study of phase transitions in the thiourea 1,1,2,2-tetrachloroethane clathrate compound

“…This was shown to occur in hydroquinone [5][6][7][8][9][10][11][12], urea [13,14] and thiourea [15][16][17] clathrate compounds, as they undergo phase transitions at low temperatures. Importance of guest-guest interaction is now being recognized in the theory of clathrate stability [24][25][26]. Importance of guest-guest interaction is now being recognized in the theory of clathrate stability [24][25][26].…”