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在甲醇氧化制甲醛反应中,银催化剂表面微量的铁将导致甲醛选择性下降,从而降低催化剂的使用寿命.研究其表面的结果表明,毒化的银催化剂表面的铁以氧化物形式存在.铁含量较低时,低氧化态的FeO为主要表面物种,铁借助于与之配位的氧原子与银表面发生强相互作用,形成四氧配位的平面结构;表面铁覆盖度的增加,导致了平面结构向八面体结构的转变,表面逐渐生成高氧化态的α-Fe_2O_3并趋向于聚集成岛,此时银铁间的相互作用消失.本文报道了用表面反应谱仪(TPRS)和表面功函数测量等方法研究氧、甲醇在毒化催化剂表面吸附和氧化反应机理的实验结果.
In methanol oxidation to formaldehyde reaction, a trace amount of iron on the surface of the silver catalyst will lead to the selective reduction of formaldehyde, thus reducing the service life of the catalyst.Studies on the surface of the results show that the poisoning of the surface of the silver catalyst oxides exist as iron content At lower temperatures, FeO in low oxidation state is the main surface species. Due to the strong interaction between the oxygen atoms and the silver surface, iron forms a planar structure with tetrahedral oxygen. The increase of surface iron coverage leads to Plane structure to octahedron structure changes, the surface gradually generate high oxidation state of α-Fe_2O_3 and tend to gather into islands, at this time the interaction between silver and iron disappear.This paper reports the use of surface reaction spectrometer (TPRS) and surface work Function measurement and other methods to study the experimental results of the adsorption mechanism of oxygen and methanol on the poisoning catalyst surface and the oxidation reaction mechanism.