Synthesis and Application to Shape Selective Reaction of Microporous Heteropoly Compounds

最近以H_3PW_< 12bbb_ O_<40>和Cs^+为原料合成了多孔杂多化合物，并表现出形状选择性催化作用。有趣的是，随着Cs含量的变化，酸性Cs盐的孔隙大小从微孔变为中孔。我们研究了这些多孔杂多化合物作为耐水催化剂和形状选择性催化剂的催化作用。在相对压力为0.2的条件下，测定了不同分子大小的分子的吸附量。Cs2.5和Pt-Cs2.5对所有分子均有明显的吸附作用。然而，Pt-Cs2.1和Pt-Cs2.1只吸附了N_2(3.6*)，而苯（5.9*）、2,2-二甲基丙烷（6.2*）、CCl_4（6.9*）和1,3,5-三甲苯（7.5*）未被吸附，说明Cs2.1和Pt-Cs2.1的孔径均为3.6-5.9*。N_2等温线显示Cs2.5和Pt-Cs2.5为介孔结构。在343k下水解2-甲基苯基乙酸酯，cs2.5的活性远优于H-ZSM-5、丝光沸石、SO_4^22-/ZrO_2、Nb_2O_5和SiO_2-Al_2O_3等氧化物催化剂。表明Cs2.5是一种很有前途的耐水固体酸。2,3-二甲基-2-丁烯水化反应的活性顺序（以催化剂重量为单位）为Cs2.5>H-ZSM-5>>Nb_2O_5-SiO_2-Al_2O_3-SiO_2-TiO_2（-0）。这也支持了Cs2.5作为耐水固体酸的高效催化功能。Pt-Csx催化烯烃的加氢和烷烃的完全氧化。乙烯加氢的活度（单位重量）为Pt-Cs2.1: Pt-Cs2.5=0.5: 1.0。另一方面，Pt-Cs2.1的活性低于Pt-Cs2.5的1%。由于环己烯没有吸附在Pt-Cs2.1上，这表明Pt-Cs2.1是一种高效的形状选择催化剂。此外，Pt-Cs2.1对烷烃的氧化表现出形状选择性。

Recently porous heteropoly compounds were synthesized from H_3PW_<12>O_<40> and Cs^+, and showed shape selective catalysis. Interestingly, the pore dimension of the acidic Cs salts varied from micropores to mesopores by changing the content of Cs. We have studied the catalysis of these porous heteropoly compounds as water tolerant catalysts and shape selective catalysts.Adsorption of various molecules having different molecular size was measured under the relative pressure of 0.2. Cs2.5 and Pt-Cs2.5 adsorbed appreciably all the molecules. However, only N_2 (3.6*) was adsorbed on Pt-Cs2.1 and Pt-Cs2.1, but benzene (5.9*), 2,2-dimethylpropane (6.2*), CCl_4 (6.9*) and 1,3,5-trimethylbenzene (7.5*) were not adsorbed indicating that both Cs2.1 and Pt-Cs2.1 possess the pore widths of 3.6-5.9*. Isotherm of N_2 revealed that Cs2.5 and Pt-Cs2.5 were mesoporous.Hydrolysis of 2-mehtylphenyl acetate was performed at 343K.Cs2.5 was far superior in the activity to other oxide catalysts such as H-ZSM-5, mordenite, SO_4^22-/ZrO_2, Nb_2O_5 and SiO_2-Al_2O_3., showing that Cs2.5 is a promising water-tolerant solid acid. For hydration of 2,3-dimethyl-2-butene, the order of activity (in the unit of catalyst weight) was Cs2.5>H-ZSM-5>>Nb_2O_5-SiO_2-Al_2O_3-SiO_2-TiO_2 (-0). This also support the efficient catalytic function of Cs2.5 as a water-tolerant solid acid.Pt-Csx catalyzed the hydrogenation of alkenes and complete oxidation of alkanes. The activity (per unit weight) for the hydrogenation of ethylene was Pt-Cs2.1 : Pt-Cs2.5=0.5 : 1.0. On the other hand, the activity of Pt-Cs2.1 was less than 1% that of Pt-Cs2.5. Since cyclohexene was not adsorbed on Pt-Cs2.1, this result shows that Pt-Cs2.1 is an efficient shape selective catalyst. Furthermore, Pt-Cs2.1 exhibited shape selectivity for the oxidation of alkanes.