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浸渍干燥的铱/氧化铝和铂/氧化铝催化剂经不同温度处理后,用DRS,XRD,WDX,XPS等进行测定。经200℃处理后,[IrCl_6]~(2-)-络离子转变为[IrCl_6]~(3-),亦即Ir(Ⅳ)转变为Ir(Ⅲ),而Pt络离子没有价态变化。400℃处理时,两种金属络离子开始有结构和配位体的变化。700℃处理后,铱/氧化铝体系表面形成IrO_2和Al-O-Ir-Cl物类,铂/氧化铝体系未发现氧化铂,但有Pt与Al_2O_3表面结合生成的较难还原的物类。两者的金属分散度均以400℃处理再经还原时最高。这是由于Ir或Pt络离子与Al_2O_3有较强的相互作用,在热处理和还原时,金属原子在载体表面上较难扩散和移动。
Impregnated dry iridium / alumina and platinum / alumina catalysts were treated with different temperatures and then measured by DRS, XRD, WDX, XPS and so on. The transition of [IrCl_6] ~ (2 -) - complex ions to [IrCl_6] ~ (3-), ie Ir (Ⅳ) to Ir (Ⅲ) after 200 ℃ treatment, while the Pt ions have no valence change. At 400 ° C, both metal complexes begin to have structural and ligand changes. At 700 ℃, IrO2 and Al-O-Ir-Cl species were formed on the surface of iridium / alumina system, while platinum / alumina system showed no platinum oxide, but more difficult species were formed by the combination of Pt and Al 2 O 3 surface. Both metal dispersions were treated at 400 ℃ and then restored by the highest. This is because the Ir or Pt complex ions strongly interact with Al 2 O 3, and the metal atoms are more difficult to diffuse and move on the support surface during heat treatment and reduction.