MgO在NaY沸石上的分散及其催化性能

DISPERSION OF MgO ON NaY ZEOLITE AND ITS CATALYTIC BEHAVIOR

采用微波辐射方法将ＭｇＯ直接分散在ＮａＹ沸石上，从而获得强碱性活性位．ＭｇＯ／ＮａＹ具有耐水冲刷性，克服了通常负载型固体碱在水中易流失的弱点。

MgO was directly dispersed onto zeolite NaY by microwave irradiation to form strong basic sites with high waterstability. Such high waterstability of MgO modified zeolite resulted from the especially low solubility of MgO in water, which could be useful for expanding the application of solid strong bases in those catalytic processes involving water in the reactants or products. In the isomerization of cis2butene at 273 K, MgO/NaY exhibited a considerable activity that increased as the loading amount was raised. The activity of MgO/NaY was higher than that of KNO3/KL and KF/AlPO45, and was in proportional to the total basicity formed on MgO/NaY sample instead of the soluble basicity. Dispersion of MgO on zeolite NaY created catalytic activity for the dehydrogenation of isopropanol, but it suppressed the dehydration reaction owing to the cover and/or neutralization of acid sites. Moreover, if the yield of acetone, formed in the dehydrogenation, was given in the units of mmol per gram MgO per hour,the values of MgO/NaY and MgO/KL sample were obviously higher than that of MgO itself. This enhance in catalytic activity should be attributed to the high dispersion of MgO on zeolite expanding the surface area of MgO. MgO/NaY showed activity similar to MgO in aldolisation of acetone at 333 K, but the selectivity for diacetone alcohol on MgO/NaY was higher than that on MgO. As a comparison, MgO loaded on alumina or silica exhibited a lower activity than MgO. Based on these facts it was clear that dispersion of MgO on zeolite by microwave irradiation could be a novel way to prepare strong basic shapeselective catalysts.