Preparation, Characterization Of KCaA Molecular Sieve And NH₂-MIL-53Membrane And Their CO₂Capture Separation Capacities

In this work, we summarized the research background, preparation method, and application ofthe porous materials. Based on this, a novel route including the pre-filling and ion exchange wasdeveloped to synthesize the KCaA molecular sieve. The effects of the ion exchange time, differentpre-filling solvents and the tested pressure on the crystal morphology, structure and sorptioncapacity were investigated. The results show that the as-prepared KCaA molecular sieve displayhigher CO₂sorption capacity and the ideal separation factor of CO₂/N₂reached to more than120;NH₂-MIL-53membrane with high permeance of H₂and high ideal separation factor of H₂/CO₂was successfully fabricated by the secondary growth method after the acquisition of theNH₂-MIL-53crystals by hydrothermal synthesis process. The detailed works are summarized asfollows:1. First, KCaA molecular sieves were prepared by traditional ion exchange method. Second, theinner channel pores of CaA molecular sieve were pre-filled by organic solvents, then KCaAmolecular sieve was prepared by ion exchange method with pre-filled CaA molecular sieve andKCl solution as raw materials. And the influences of ion exchange time and degree, the pre-fillingorganic solvents on the sorption capacity of as-prepared KCaA were investigated under differention exchange method and preparation conditions were optimized.2. The solution of Al（NO₃）₃·9H₂O, NH₂-BDC and deionized water was used as the raw materialsto synthesize NH₂-MIL-53powder, then the as-prepared NH₂-MIL-53crystals were used to seedthe α-Al₂O₃support. NH₂-MIL-53membrance was synthesized by the second growth method. Theinfluences of different seed contents and synthesis time on the permeation of the membrance wereinvestigated and preparation conditions were optimized.3. XRD, SEM and EDS tests were used to characterize the morphology and structure of theas-prepared KCaA molecular sieve. In addition, PCT tests were used to characterize the CO₂sorption capacity and test conditions of the as-prepared KCaA molecular sieve were optimized. It’sfound that the morphology and structure of the molecular sieve did not been changed and the CO₂ sorption capacity was enhanced after ion exchange. Moreover, the CO₂sorption capacity of theas-prepared KCaA molecular sieve obtained by the pre-filling ion exchange method was higherthan obtained by the traditional ion exchange method.4. XRD and SEM tests were used to characterize the morphology and structure of theas-prepared NH₂-MIL-53membrance. And single gas permeation testing using CO₂,N₂, H₂andCH₄was employed to evaluate the permeation property of the NH₂-MIL-53membrane by apressure gradient method at room temperature. The results show that a dense, continuous, high H₂permeance and reasonable ideal selectivity of H₂/CO₂amine-functionalized MIL-53membranewas obtained and its thickness was about4μm.