Microwave hydrothermal synthesis and performance of NaA zeolite monolithic adsorbent with honeycomb ceramic matrix

Abstract

The NaA monolithic adsorbent composed of NaA zeolite and honeycomb ceramic matrix has been considered as an up-and-coming adsorbent for the utilization in adsorptive rotary dehumidification system. This contribution introduced a novel synthesis strategy of NaA monolithic adsorbent on the honeycomb ceramic matrix —— in situ microwave hydrothermal synthesis. Meanwhile, the influence of several key factors during the synthesis process, including CaCl2 concentration, seed coating, microwave temperature and time, on the performances of the adsorbent was systematically analyzed. The crystalloid phase and the morphology of the as-synthesized adsorbent were used to determine by X-ray powder diffraction and Scanning electronic microscope, and its adsorption and desorption performances were measured by static adsorption and temperature programmed desorption, respectively. The test results of X-ray powder diffraction and Scanning electronic microscope indicated that NaA zeolite with cubic form and particle size of about 0.9 μm could be quickly in situ synthesized on both the surface and the void of honeycomb ceramic matrix within 35–55min by microwave irradiation. Because of smaller size, more uniform distribution of NaA zeolite, the novel monolithic adsorbent synthesized by microwave method showed more excellent adsorption and desorption performances than that by traditional impregnation technology, which displayed a higher saturated adsorption ratio and faster early adsorption rate, as well as a lower desorption activation energy.