芳烃精制颗粒白土失活分析及再生初探

Characterization of Physicochemical Properties of Deactivated Particulate Clay Used in Aromatic Hydrocarbon Refining and Its Regeneration

采用BET、TG、TPO、UV-Vis光谱、XRD和NH3-TPD等方法对芳烃精制失活颗粒白土进行了表征,分析了颗粒白土的失活原因,并对其再生方法进行了初探。研究结果表明,由于在颗粒白土表面沉积了较大分子的多烷基苯及稠环化合物,造成颗粒白土的孔道尤其微孔被堵塞,颗粒白土的比表面及孔容大幅度降低,同时表面酸中心数目明显减少,造成颗粒白土的脱烯烃精制性能降低,从而逐渐失活。在适宜的温度条件下经空气氧化后失活颗粒白土的比表面、孔结构、表面酸性及活性得到一定程度的恢复,其物相结构没有发生明显的变化。

Particulate clay is commonly applied in the refining of aromatic hydrocarbon, and it will deactivate after a period of use. In this study, deactivated particulate clay was characterized by means of BET, TG, TPO, UV-Vis, XRD, and NH3-TPD, and the mechanisms of deactivation were analysed. Because it was of acidic, the particulate clay catalysed olefins to polymerize each other or alkylate with aromatic hydrocarbon, and larger molecules formed. When these larger molecules were not removed by aromatic hydrocarbon fluid, they would overlay the surface of particle clay, and occupy the pores of particle clay. Thus, the number of acidic sites as Well as the specific surface of particle clay decreased, and the particulate clay deactivated gradually. Owing to lower reaction temperature in the aromatic hydrocarbon refining, the phase of particulate clay did not change after deactivation, and so the phase had no relation with the deactivation of particulate clay. By the oxidation with air under the proper temperature, the deactivated particle clay restored its specific surface area, pore volume, and activity to a great extent.