Indirect tests are most often used in the studies of the tetrahydrofuran (THF) but their shortcomings are obvious: not only can the quantities of reactants and final products not be measured directly, but the test results are greatly influenced by experimental environment, instrument accuracy, and calculation error. In view of this, the low-field nuclear magnetic resonance (NMR) was adopted to investigate into the characteristics of THF hydrate formation process. The low-field NMR proton spin-spin relaxation time (T2) distribution measurements were employed to investigate tetrahydrofuran (THF) water clathrate hydrate formation process in 19% THF aqueous solution starting from room temperature. The experiments show that the T2 distribution and the cumulative signals are well correlated to the temperature, which proves that the formation of the THF clathrate hydrate is closely related to the temperature. According to the change in the cumulative NMR signals, the whole formation process of the THF clathrate hydrate is divided into initial, induction, accelerating, and steady stages. The cumulative NMR signals in the induction stage are fluctuating because the unsteady hydrate cluster decomposes and grows in size randomly; but after this induction stage, when the crystal nucleus of hydrate cluster reaches the critical size, hydrate starts to generate in a great volume. And with more and more hydrate forms, less and less THF solution is left, and the formation of hydrate becomes slow until it comes to the steady stage.
