纳米MgO对六氟丙烷热分解性能影响及机理研究

摘要

研究了纳米MgO在管式反应器中对六氟丙烷热分解性能的影响,用在线气相色谱（GC）、气相色谱-质谱（GC-MS）、离子色谱仪（IC）对热分解气体进行分析,采用X射线衍射仪（XRD）及X射线光电子能谱仪（XPS）对作用前后的纳米MgO晶型和组成进行表征。研究表明,六氟丙烷高温热分解时主要发生脱氟化氢（HF）的反应。在空管中随着反应温度的增加,六氟丙烷的分解率提高,而加入纳米MgO后六氟丙烷分解率均增大,在700℃时,六氟丙烷的分解率由空管时的23.9%增加到100.0%,同时热分解气体中HF的含量比空管时降低%The thermal decomposition characteristics of hexafluoropropane were studied in tubular reactor.The contents of decomposed gas were studied by gas chromatography online（GC）,gas chromatography-mass spectrometry（GC-MS） and ion chromatography（IC）,while nanocrystalline MgO was characterized by X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）.The results show that dehydrofluorinationg of hexafluoropropane is the main reaction and pentafluoropropylene is the primary product.It also indicates that the higher reaction temperature can promote hexafluoropropane decomposition in the empty tubular reactor.When nanocrystalline MgO is filled in the reactor,hexafluoropropane decomposition rate increases.As the reaction temperature increases,hexafluoropropane decomposition rate enhances.After nanocrystalline MgO added under 700℃,hexafluoropropane decomposition rate raises from 23.9% in empty tubular reactor to 100% and HF content in thermal gas product decreases by 42.4%.The XRD and XPS patterns reveal a composition system of MgF2/MgO is formed.The mechanism of MgO on the thermal decomposition of hexafluoropropane was preliminarily studied.That partial MgO reacted with HF and was transferred to MgF2 during the reaction.The resulting MgF2 are very active catalysts for HF elimination from hexafluoropropane.