Growth of Silicalite–1 Coatings on SiC Foam Support

Solid polycrystalline silicon particles were used as Si source for in situ hydrothermal synthesis of continuous silicalite–1 coating on SiC foam support in this paper. It is supposed that the Si dissolution rate was suppressed by using solid Si source, which subsequently led to zeolite crystals preferential nucleation and growth on the support. The loading amount, crystal size, layer thickness and specific surface area of the synthesized zeolite coatings were investigated with respect to the polycrystalline silicon particle amount and concentration of NaOH and reaction time. It is found that continuous zeolite layer can not form on the SiC foam ceramic support with too low amount of polycrystal silicon, because of the low concentration of silicic acid radical ions in the solution. By contrast, when the polycrystal silicon amount is too high, the zeolite loading on the support is low. In addition, increasing the NaOH concentration can promote silicon dissolution, increase the saturation concentration of silicon, promote the zeolite nucleation, and increase the loading of zeolite crystals. Zeolite layer with the maximum loading amount of zeolite and a specific surface area of 81 m2g 1 was fabricated on the SiC foam support under optimum conditions.