Shape-selective oxidation catalysed by a Pt-promoted ultramicroporous heteropoly compound
Shape-selective oxidation catalysed by a Pt-promoted ultramicroporous heteropoly compound
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Pt促进的超微孔杂多化合物催化的择形氧化
DOI：
10.1039/a802913j
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
T. Okuhara
中科院分区：
文献类型：
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作者：
Y. Yoshinaga;T. Okuhara
合成了 Pt 促进的多孔杂多化合物 Pt-CsxH3-xPW12O40，其微孔和介孔尺寸分布分别通过不同尺寸分子的吸附和 Dollimore-Heal N2 等温线方法确定。 0.5 wt.% Pt-Cs2.1H0.9PW12O40 显示出具有平台的 I 型 N2 吸附等温线，表明存在几乎均匀的微孔； 1.0 wt.% Pt-Cs2.1H0.9PW12O40、1.5 wt.% Pt-Cs2.1H0.9PW12O40 和 0.5 wt.% Pt-Cs2.5H0.5PW12O40 给出了 IV 型等温线，正如通常在中孔材料中观察到的那样。 N2 [分子大小 (MS) = 0.36 nm]、正丁烷 (MS = 0.43 nm)、异丁烷 (MS = 0.50 nm)、苯 (MS = 0.59 nm)、2,2-二甲基丙烷 (MS = 0.62 nm) 和 1,3,5-三甲苯 (MS = 0.75 nm) 等分子的吸附表明，孔径0.5 wt.%Pt-Cs2.1H0.9PW12O40 的波长范围为 0.43–0.50 nm，外表面积非常小。由于孔径受限，0.5 wt.% Pt-Cs2.1H0.9PW12O40 在催化氧化方面表现出高效的形状选择性；较小的分子如甲烷 (MS = 0.38 nm) 和 CO (MS = 0.38 nm) 很容易被氧化，而苯 (MS = 0.59 nm) 则不会被氧化。这种有效的形状选择性表明 Pt 仅存在于孔中，而不存在于 0.5 wt.%Pt-Cs2.1H0.9PW12O40 的外表面上。
Pt-promoted porous heteropoly compounds, Pt-CsxH3-xPW12O40, have been synthesized and their micro- and meso-pore size distributions determined by adsorption of variously sized molecules and the Dollimore–Heal N2 isotherm method, respectively. 0.5 wt.% Pt-Cs2.1H0.9PW12O40 showed a Type I N2 adsorption isotherm with a plateau, indicating the presence of nearly uniform micropores; 1.0 wt.% Pt-Cs2.1H0.9PW12O40, 1.5 wt.% Pt-Cs2.1H0.9PW12O40 and 0.5 wt.% Pt-Cs2.5H0.5PW12O40 gave Type IV isotherms, as usually observed for mesoporous materials. Adsorption of molecules such as N2 [molecularsize (MS) = 0.36 nm], n-butane (MS = 0.43 nm), isobutane (MS = 0.50 nm), benzene (MS = 0.59 nm), 2,2-dimethylpro-pane (MS = 0.62 nm), and 1,3,5-trimethylbenzene (MS = 0.75 nm) demonstrated that the pore width of 0.5 wt.%Pt-Cs2.1H0.9PW12O40 was in the range 0.43–0.50 nm and that the external surface area was very small. Owing to the restricted pore size, 0.5 wt.% Pt-Cs2.1H0.9PW12O40 exhibited efficient shape selectivity for catalytic oxidation; smaller molecules such as methane (MS = 0.38 nm) and CO (MS = 0.38 nm) were readily oxidized, whereas benzene (MS = 0.59 nm) was not oxidized. This efficient shape selectivity indicates that Pt is present exclusively in the pores and not on the external surface of 0.5 wt.%Pt-Cs2.1H0.9PW12O40.