NiO/ZnO-Al_2O_3-SiO_2吸附剂反应吸附脱硫机理

Mechanism of reactive adsorption desulfurization over NiO/ZnO-Al_2O_3-SiO_2 adsorbents

对比考察了N_2和H_2载气下NiO/ZnO-Al_2O_3-SiO_2吸附剂对模拟汽油的吸附脱硫效果。与H_2气氛下的脱硫效果相比,N_2载气下吸附剂也具有明显脱硫效果,吸附剂表面积炭导致其脱硫效率降低,从而推断出NiO可以直接进行反应吸附脱硫反应。对不同载气和还原条件下反应前后吸附剂进行XRD、H_2-TPR、TOPT和XPS等表征结果表明:反应吸附条件下,吸附剂载体表面NiO难以被还原成单质Ni,说明H_2气氛下反应吸附过程中吸附剂中的NiO与单质Ni可能共同参与反应,反应后吸附剂上NiS_x存量极少。根据以上研究结果,提出了NiO为活性中心的反应吸附脱硫机理。

The reactive adsorption desulfurization （RADS） of a model gasoline was investigated over a NiO/ZnO-A1203-SiO2 adsorbent. N2 and HE were used as carrier gases, and their desulfurization results were compared. Results showed that the adsorbent performed well when using N2 as the carrier gas. Carbon deposition on the surface is the main reason of the drop of desulfurization efficiency. This indicates that NiO could directly react with sulfur compounds in gasoline without the presence of HE. Results of XRD, HE-TPR, TOPT and XPS showed that NiO is hard to be reduced under conditions of RADS. RADS process mainly depends on the reaction of NiO and Ni to remove sulfiar comnounds. At last. a nossible RADS mechanism was nresented and discussed.