Formation and Microstructure of Zeolite Silicalite-1 Membranes on α-Al_2O_3 Supports with Different Pore Sizes

The formation and microstructure of zeolite silicalite-1 membranes on the α-alumina supports with different pore sizes by secondary growth synthesis from clear solutions were studied. The deposition of the seeds with 100nm and 600nm sizes and growth of the membranes on the different supports were investigated, respectively. SEM and XRD characterization of the samples shows that a continuous uniform seed layer and dense, intergrown membrane on the support with the pore size of 0.1μm can be obtained by using both 100nm and 600nm size seeds, whereas, on the support with the pore size of 4μm, a continuous seed layer can not be formed by using the same seeding time for either 100nm or 600nm seeds. On the support with the pore size of 4μm, a seed layer can only be obtained by using 100nm seeds in a longer contact time, however, 600nm seeds cannot be deposited to form a seed layer. The seed layers and membranes grown from the smaller seeds are better intergrown and possess smooth surfaces, whereas the seed layers and membranes grown from the larger seeds display coarse surfaces and poorer intergrowth.