不同阳离子Y分子筛上金属络合物的吸附和分解 Ⅱ.Co(CO)_3NO吸附和分解的红外光谱表征

ADSORPTION AND DECOMPOSITION OF METAL COMPLEXES ON YZEOLITES OF DIFFERENT TYPES OF CATION Ⅱ. Infrared Spectroscopic Study of Co(CO)3NO Adsorption

采用红外光谱表征了含不同阳离子的Ｙ分子筛上Ｃｏ（ＣＯ）３ＮＯ的吸附和分解及其和阳离子的作用．结果表明，Ｃｏ（ＣＯ）３ＮＯ吸附后主要形成Ｃｏ（ＣＯ）ｘＮＯ（ｘ＝２，３），并出现热稳定性较高的Ｃｏ（ＮＯ）２＋２．产生Ｃｏ（ＮＯ）２＋２的机制和最终分解产物与分子筛阳离子的性质有关．ＮａＹ上Ｃｏ（ＣＯ）ｘＮＯ歧化产生少量Ｃｏ（ＮＯ）２＋２，分解产物主要为Ｃｏ（０）；ＣｏＹ中Ｃｏ２＋的存在部分避免了Ｃｏ（ＣＯ）ｘＮＯ的歧化，分解得到的Ｃｏ（０）含量较高；ＮｉＹ，尤其ＣｕＹ阳离子和吸附物种发生电子转移，形成ＮＯ＋中间物种，氧化Ｃｏ（０）产生Ｃｏ（ＮＯ）２＋２，分解产物为Ｃｏ（０）和Ｃｏ（Ⅱ）的混合物．

Infrared spectroscopy was used to investigate the adsorption and decomposition of Co(CO)_3NO on MY zeolites (M=Na^+, Ni~2+, Co^2+and Cu^2+). It was found that the main adsorption species on the zeolites are Co(CO)_xNO_(x=2,3). Upon evacuation at an elevated temperature, part of Co(0) species is oxidized due to the interaction of Co(CO)_xNO with zeolite cations. In the case of Co(CO)3NO/NaY, the disproportionation of adsorption species results in the appearance of small amount of Co(NO)_2~2+. Due to the presence of Co^2+cations in CoY, NO resulting from the decomposition of Co(CO)_3NO can directly interact with the zeolite cations, Co^2+, to form Co(NO)_2~2+, which, to some extent, avoids the oxidation of Co(0). However, for NiY, especially for CuY, because of the occurrence of the reaction of zeoltie cations with adsorption species, substantial amount of Co(0) species is oxidized into Co(Ⅱ) and the fully decomposed products on the zeolites are the mixture of Co(0) and Co(Ⅱ).