Adsorption separation of carbon dioxide, methane and nitrogen on monoethanol amine modified β-zeolite

Abstract

A new type of composite adsorbents was synthesized by incorporating monoethanol amine (MEA) into β-zeolite. The parent and MEA-functionalized β-zeolites were characterized by X-ray diffraction (XRD), N 2 adsorption, and thermogravimetric analysis (TGA). The adsorption behavior of carbon dioxide (CO 2), methane (CH 4), and nitrogen (N 2) on these adsorbents was investigated at 303 K. The results show that the structure of zeolite was well preserved after MEA modification. In comparison with CH 4 and N 2, CO 2 was preferentially adsorbed on the adsorbents investigated. The introduction of MEA significantly improved the selectivity of both CO 2/CH 4 and CO 2/N 2, the optimal selectivity of CO 2/CH 4 can reach 7.70 on 40 wt% of MEA-functionalized β-zeolite (MEA(40)-β) at 1 atm. It is worth noticing that a very high selectivity of CO 2/N 2 of 25.67 was obtained on MEA(40)-β. Steric effect and chemical adsorbate-adsorbent interaction were responsible for such high adsorption selectivity of CO 2. The present MEA-functionalized β-zeolite adsorbents may be a good candidate for applications in flue gas separation, as well as natural gas and landfill gas purifications.