二苯并噻吩在γ-Al_2O_3上分散状态及吸附状态的研究

STUDIES ON DISPERSION AND ADSORPTION STATES OF DIBENZOTHIOPHENE ON γ-Al_2O_3

二苯并噻吩 (DBT)在较缓和的条件下即可在γ Al2 O3 表面发生自发单层分散 ,通过XRD分析测定其分散阈值为 0 2 8g/g (γ Al2 O3 ) ,大于经计算得出的 0 19g/g (γ Al2 O3 )的平躺吸附密置单层分散容量 ,推测DBT在γ Al2 O3 表面存在两种吸附状态 :除通过π电子的平躺吸附外 ,还存在通过硫原子的端连吸附。FT IR分析结果与上述推测相一致 ,萘的对比试验更进一步证实了上述推测 ,认为DBT可能通过硫原子吸附在γ Al2 O3 表面的酸中心上。

Dibenzothiophene(DBT) can disperse easily and spontaneously onto the surface of γ Al 2O 3 under relatively mild conditions. It is determined by XRD that the dispersion threshold of DBT is 0.28 g/g( γ Al 2O 3). This value is obviously bigger than the calculated value of monolayer dispersion of DBT assuming DBT flat adsorbed on the surface of γ Al 2O 3. It is inferred from this result that the adsorption of DBT on the surface of γ Al 2O 3 may exist in two states, one is the end on manner through the adsorption of sulfur atom, the other is the flat manner through the adsorption of π electrons of DBT molecule. The result of FT IR analysis did not contradict with the inference. The experimental results of naphthalene adsorption on γ Al 2O 3 further proved the inference. DBT may be adsorbed on the acidic sites of γ Al 2O 3 surface via sulfur atom.