Shape selectivity of Porous Glass Prepared from Borosilicate Glass

当含有特定成分的硼硅玻璃在熔点以下加热时，玻璃分为两相；一个是Nao-B_2O_3富相，另一个是SiO_2富相。由于前相被盐酸浸出，用硼硅酸盐玻璃制备多孔玻璃。在硼硅酸盐玻璃中加入微量氧化铝，可以控制多孔玻璃的微孔尺寸分布。微孔尺寸随着氧化铝含量的增加而减小，这是由于抑制了硼硅酸盐玻璃的相分裂。当氧化铝的添加量达到3 wt%时，多孔玻璃的表面积增加，但当添加量超过4 wt%时，玻璃的表面积迅速减小。在多孔玻璃上的镍和铂催化剂上进行了甲基取代苯、己烯和1-烯烃的加氢反应。虽然所有反应物的加氢速率不依赖于氧化铝含量高达3wt %，但随着氧化铝含量超过4wt %，大体积分子的加氢速率下降。这些结果表明，少量氧化铝的加入使其孔径从中孔范围向微孔范围变化，并具有形状选择性。该新型催化剂载体可由不同氧化铝含量的硼硅酸盐玻璃制备。

When a borosilicate glass with a specified component was heated under the melting point, the glass divided into two phases ; one was Nao-B_2O_3 rich phase and the other was SiO_2. Since the former phase was leached out from the glass by hydrochloric acid, a porous glass was prepared from the borosilicate glass. The micropore size distribution of a porous glass prepared from a borosilicate glass was controlled with the addition of minute amount of alumina. The micropore size decreased with the alumina content due to the suppression of the phase splitting of the borosilicate glass. The surface area of the porous glass increased by the alumina addition up to 3 wt%, but the area rapidly decreased with the addition above 4 wt%.The hydrogenation of methyl groups substituted benzenes, hexenes and 1-olefins was carried out over the nickel and platinum ctalysts supported on the porous glasses. Although the hydrogenation rates of all reactants was not dependent upon the alumina content up to 3 wt%, the rates of bulky molecules decreased with the alumina above 4 wt%. These results indicate that the pore size changes from mesopore range to micropore range with shape selectivity by the addition of small amount of alumina. The novel catalyst support can be prepared from borosilicate glasses with different content of alumina.