(225c) Methane Enclathration with New Hydrophobic and Hydrophilic Aromatic Compounds

This work addresses the clathrate hydrate formation of new heterocyclic aromatic compounds, hydrophobic pyrrole (C₄H₄NH) and hydrophilic pyridine (C₅H₅N) with methane. These cyclic compounds can be a monomer for kinetic hydrate inhibiting polymers but their size can fit the water cavity. We have explored the possibility of binary hydrates between aromatic compound and methane. We measured cage occupancy and phase equilibrium of the binary heteroaromatic compound hydrates. Both binary (pyrrole + methane) and (pyridine + methane) gas hydrates have a cubic Fd3m structure II determined by powder X-ray diffraction patterns. Raman spectroscopy clearly presents methane enclathration occurring in the small and large cage of sII hydrate structure, but both of heteroaromatic compounds were captured in only large cage of sII hydrate structure. Calorimetric measurements with micro-differential scanning calorimeter provided hydrate equilibrium information of binary (pyrrole + methane) and (pyridine + methane) clathrate hydrates. That result shows that the binary heteroaromatic compound hydrates can easily form than pure methane hydrate. Thus, we should carefully monitor the purity of polymer hydrate inhibitor, because their monomers can enhance the hydrate formation.