Synthesis of 5A zeolite coating/PSSF composites and the application for adsorption of methane from air

Abstract

To remove lean methane from air, an adsorption process involving a fixed-bed filled with small adsorbents is often used. This process, however, has some drawbacks such as large bed pressure drop and low bed utilization. To overcome these shortcomings, we fabricated 5A zeolite coating/paper-like sintered stainless steel fiber (PSSF) composites by using an in situ hydrothermal method on a 3-aminopropyltrimethoxysilane-functionalized support. The composites have large external surface areas and high voidages. They were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N₂ adsorption/desorption. Moreover, we packed these composites at the end of fixed beds to form structured fixed beds and tested adsorption dynamics. We analyzed the breakthrough curves obtained from adsorption dynamics by the length of the unused bed model (LUB). Results showed that the composites were successfully prepared with dense coating. Furthermore, the breakthrough curves of structured fixed beds were steeper than that of the fixed bed. We concluded that by forming structured fixed beds with 5A zeolite coating/PSSF composites, the bed pressure drop could be reduced and the bed utilization could be improved.