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用XPS和静态SIMS研究了110～600K温度范围内甲醇在Pd(111)面上的吸附和解离表面化学反应。实验结果表明,甲醇在Pd(111)面上的热解离反应途径依赖于其初始暴露量。在110K低温下,暴露量为1.5L时达到单层饱和吸附。在此暴露量以下,甲醇在表面的热解离占主导地位,其解离的中间吸附物种有CH_3ads、CH_3Oads和H_2Oads。这表明在Pd(111)面上,不仅甲醇中O-H键,而且C-O键也被活化。而在初始暴露量大于1.5L时,甲醇从表面的热脱附趋于主导地位。Pd(111)面上相对稳定的中间吸附物种CH_3ads的存在可能有助于理解Pd催化剂在合成CH_3OH、CH_4、CH_3OCH_3和CH_3CH_3反应中的催化作用机理。
The adsorption and dissociation reactions of methanol on the Pd (111) surface in the temperature range of 110-600 K were investigated by XPS and static SIMS. The experimental results show that the thermal dissociation reaction pathway of methanol on the Pd (111) surface depends on its initial exposure. Under 110K low temperature, the single-layer saturated adsorption reached 1.5L. Below this exposure level, the thermal dissociation of methanol on the surface dominates. The intermolecular adsorbed species of CH_3ads, CH_3Oads and H_2Oads are dissociated. This shows that not only the O-H bond in methanol, but also the C-O bond is activated on the Pd (111) plane. When the initial exposure is more than 1.5L, the thermal desorption of methanol from the surface tends to dominate. The presence of relatively stable intermediate adsorbed species CH_3ads on the Pd (111) surface may help to understand the catalytic mechanism of the Pd catalyst in the synthesis of CH_3OH, CH_4, CH_3OCH_3 and CH_3CH_3 reactions.