微孔磷酸铝AIPO_4-HDA的热分解过程研究

Thermal Decomposition of Microporous Aluminophosphate AlPO_4-HDA

采用差热-热重-质谱(TG-DTA-MS)、粉末X射线衍射(XRD)、红外光谱(FTIR)和固体核磁(Solid-State-MAS-NMR)等技术详细地研究了微孔磷酸铝晶体AlPO_4-HDA中模板剂的热分解过程.结果表明,该模板剂的热分解分3步进行:第一步是模板剂和无机骨架之间的部分氢键断裂;第二步为模板剂的Hof-mann降解反应和β-消除反应;第三步是残留积碳的氧化分解反应.固体MAS NMR的研究结果表明,随着模板剂的脱出.无机骨架中铝和磷的配位状态发生了变化.

Thermal decomposition of microporous aluminophosphate AlPO4-HDA has been investigated by using thermogravimetric-differential thermal analysis coupled with mass spectrometry(TG-DTA-MS), X-ray diffraction(XRD), Fourier transform infrared (FTIR) and solid-state MAS NMR spectroscopy. The results show that the template decomposition involves three steps. First, the H-bondings between the inorganic framework and the template are broken; then, the template undergoes sequential Hofmann degradation reactions followed by β-eliminations and oxidations; finally, the remaining organic components are removed at a high temperature. The results obtained by using MAS NMR indicate that there is a change in the coordination state of certain framework Al and P with the partial removal of the template.