Properties of dielectrics and microwave heating of zeolites with different framework structures -measurements and theoretical study

目前已有研究表明，A沸石III位上的阳离子表现出不同寻常的介电性质，并对其微波加热性能产生强烈影响。为了证实这一结论，研究了在III位有阳离子的沸石（Na_<12>-A和K_<12>-A）和没有阳离子的沸石（Na_<10>Ca_1-A、Na_8Ca_2-A、Na_4a_4-A和K_<10>Ca_1-A）的介电性能。前者阳离子运动活化能较低，后者阳离子运动活化能较高。利用介电性质计算了沸石对微波的吸收效率。前者的效率高于后者。前者易受微波辐射加热，其温度高于后者。计算所得的微波加热性能与实测值吻合较好，说明所采用的计算方法是有效的。同样的方法应用于不同骨架结构的沸石（A、L和丝光沸石）。（下文中，沸石A、L、丝光沸石分别写成-A、-L、-M。）测定的微波吸收效率依次为：Na_<12>-A>Na_6K_6-A>Na_<4.3>-M>Na_<10>Ca_1-A>K_9-L>Na_4Ca_4-A；测定的最终加热温度依次为：Na_<12>-A>Na_<4.3>-M>Na_6K_6-A>K_9-L>Na_<10>Ca_1-A>Na_8Ca_2-A>Na_4Ca_4-A。订单中有两个不同之处，下面是下划线。不同骨架结构的沸石在点上存在差异。所研究的沸石结构密度差异较大。对吸收效率进行了密度校正。修正后的吸收效率有所提高，但计算值与测量值之间的差异仍然存在。结果表明，本理论方法能有效地预测同种类沸石的微波加热性能，但与不同种类沸石的比较可能存在一定的差异。少

It has been suggested so far that cations on the site III in zeolite A show unusual dielectric properties and strongly affect properties of microwave heating. In order to confirm this suggestion, dielectric properties of zeolites (Na_<12>-A and K_<12>-A) with cation on the site III and zeolites (Na_<10>Ca_1-A, Na_8Ca_2-A, Na_4a_4-A and K_<10>Ca_1-A) without that were studied. The former showed lower activation energies of cation motion and the latter higher energies. Absorption efficiencies of zeolites for microwaves were calculated by using the dielectric properties. The former had a higher efficiency than the latter. The former was easily heated by, microwave radiation and reached higher temperature than the latter. Since the calculated properties for microwave heating were in good agreement with he properties measured, the calculation method used was judged valid.The same method was applied to zeolites with different framework structures (zeolite A, L and mordenite). (In the followi … More ngs, zeolite A, L and mordenite are written as -A, -L and -M, respectively.) Absorption efficiencies for microwaves were calculated and were in the order of Na_<12>-A>Na_6K_6-A>Na_<4.3>-M>Na_<10>Ca_1-A>K_9-L>Na_4Ca_4-A On the other hand, final heating temperatures measured were in the order of Na_<12>-A>Na_<4.3>-M>Na_6K_6-A>K_9-L>Na_<10>Ca_1-A>Na_8Ca_2-A>Na_4Ca_4-A. There were two disagreement points in the orders, which are, underlined. The disagreements appeared in the points which are between zeolites with different framework structures. There is a large difference in structural density among these zeolites studied. A correction for the density was made to the absorption efficiencies. The absorption efficiencies were improved after correction but the discrepancies between the calculation and measurements remained still.It is found from the results that the present theoretical method can validly expect the microwave heating properties in the comparison with the identical kind of zeolite but may bring about some discrepancy in the comparison with the different kinds. Less