12-钼磷酸中水的存在状态及其热稳定性的质谱法研究

本文运用程序升温脱水-质谱计检测(TPD MS)和红外光谱测定(IR)法研究了12-钼磷酸(PMA)中水的存在状态及其热稳定性. 解迭了PMA的TPD MS谱, 发现PMA中存在有结合能量各异的7种水峰. 讨论了PMA中各种水的结合强度及其对Keggin结构稳定性的影响。

Mass Spectrography Study on the Existence and Thermal Stability of Water in 12-Molybdophosphoric Acid

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...