摘要
应用原位Mossbauer谱等技术考察了PtSn/Al_2O_3催化剂中锡组分与丙烷的作用,研究了丙烷在该催化剂上的脱氢反应行为。提出了丙烷的脱氢反应模型,即负载型铂锡催化剂中的氧化态锡用于活化丙烷,而金属铂则通过反溢流过程移去活化了的丙烷中的氢,从而使丙烷催化脱氢过程得以循环进行。
The synergistic effect of metallic Pt and oxidic tin in PtSn/Al2O3 catalyst was discussed and a model describing the dehydrogenation process of propane was proposed. In-situ Mossbauer spectra showed that SnO2/Al2O3 sites could activate propane to form the Reactive Intermedi-ate(RI), which might be partially decomposed by heating to 520℃ and converted to SnO/Al2O3 and propene. The RI also might be completely resolved into SnO2/Al2O3 and propene by the relcase of H2 from RI on Pt/Al2O3 sites at 520℃. In situ ESR spectra indicated that the homogeneous breaking of C-H bond at 350℃ was obvious on PtSn/Al2O3, while no signal was found on Pt/Al2O3 at the same temperature, providing an additional evidence for the activation of propane by SnOx/Al2O3 sites. The hydrogenolysis of propane on Pt/Al2O3 and PtSn/Al2O3 revealed that propane and H2 adsorbed on different active sites of PtSn/ Al2O3. The conversion of propane on PtSn/Al2O3 under different atmospheres also supported the synergistic action of metallic Pt and tin oxides.
