Abstract: The existence and thermal stability of H_2O in 12-molybdophosphoric acid (PMA) have been studied by temperature programmed desorption-mass spectrography (TPDMS) and infrared spectrography (IR).
A PMA sample containing 19.1 H_2O/P, H_3(PMo_(12)O_(40))·17.6 H_2O, was prepared, its water content was determined according to Fig.1. The TPD MS spectrum of H_2O (m/z=18) in PMA (solid line Fig.3) was recorded after vacuum outgassing(0.27 Pa) at 290 K (the total time of outgassing in the range 77.4-290 K was 142.5 min). Separated spectra (Fig.3) and their parameters simulated by spectrogram superposition method~[7] and consulting table method~[8] (Table) show that there exist 7 kinds of H_2O in PMA.
In situ IR spectra for PMA at different conditions (Fig.4) revealed...