Cu-ZSM-5上Cu+位置的CO吸附红外光谱表征

本文以ＣＯ为探针分子系统考察了不同铜交换度的Ｃｕ－ＺＳＭ－５经不同条件预处理后吸附ＣＯ的红外光谱特征，实验结果表明；在真加热条件下，Ｃｕ＾２＾＋一定程度地自动还原为Ｃｕ＾＋甚至Ｃｕ＾０；Ｃｕ－ＺＳＭ－５中存在着两种Ｃｕ＾＋离子位（Ｓ１和Ｓ１），两种位置上Ｃｕ＾＋的氧化还原性质不同，Ｓ１位的Ｃｕ＾＋容易被氧化和还原，在热力学性质上，Ｓ１位的Ｃｕ＾＋－ＣＯ表面体比Ｓ１位的更稳定；室温下，Ｓ１位的Ｃｕ＾

CHARACTERIZATION OF Cu~(+) SITES ON Cu-ZSM-5 BY CO ADSORPTION INFRARED SPECTROSCOPY

CO is used as a probe molecule to investigate the characteristics of Cu-ZSM-5 with different exchange degrees under different pretreatment conditions by means of infrared spectroscopy. The experimental results indicate that: Cu~(2+) in Cu-ZSM-5 can be reduced to Cu~+ to some extent under evacuation and heating conditions. There are two kinds of Cu~+ site (S1 and S1 ) in Cu-ZSM-5. The redox property of Cu~+ at the two kinds of site is different from each other. Cu~+ on S1 is thermodynami-cally more stable and Cu~+ on S1 is easier to be oxidized and reduced. The Cu~+ -CO surface species located on S1 can gradually migrate to S1 at room temperature. The equilibrium of Cu~+ -CO surface species on the two kinds of site can be reached at higher temperature. The structure of the two kinds of site is also discussed.