以Fe_3(CO)_(12)为母体制备担载金属簇催化剂的表面化学研究

Surface Chemistry Studies of Supported Metal Cluster Catalyst

以表面浸渍的方法制备了以 Fe3 (CO) 12 为母体 ,SY分子筛为载体的担载型 Fe3 / SY催化剂 .采用 TPD- IR,UV- DRS,XPS,TPD- GC等技术综合研究了 Fe3 (CO) 12 与 SY载体间的相互作用、在真空中的热分解以及 Fe3 / SY上 CO吸附、CO和 H2 共吸附的动态过程 .IR结果表明 ,Fe3 (CO) 12 与载体之间存在着较强的相互作用 ,并由此使得簇结构得到稳定 ,脱羰过程中存在着结构的转变 .XPS及 TPD- GC结果均表明脱羰过程中铁被氧化 .U V- DRS结果表明 ,脱羰还原后表征 Fe- Fe键的特征谱带仍存在 ,并能对 CO再吸附 ,形成一个新的羰基簇合物 .根据 Fe3 / SY上CO和 H2 共吸附的结果 ,提出了 F- T合成中 C- O键的断裂是经由羰基氢化物的途径 ,而不是直接断裂 ,催化剂簇结构的保持可能是高催化活性的原因之一 .

Fe 3(CO) 12/SY catalyst has been prepared by impregnation method. The deca rbonylation in vacuum and CO, the adsorption of CO, CO+H 2 on Fe 3/SY have bee n studied by TPD IR, UV DRS, XPS and TPD GC. The cluster is stabilized due t o chemical interaction between the cluster and the support. From the in situ IR analysis, some structural transformation can be observed during decarbonylation . XPS and TPD GC results show that iron is oxidized during decarbonylation and Fe Fe bond is still existing. CO can be absorbed on Fe 3/SY to form a new car bonyl cluster. It seems that the broken of C O bond goes through a way of hydro carbonyl compounds from the result of CO and H 2 coadsorption on Fe 3/SY. Mayb e the higher activity is due to the preservation of the cluster skeleton.