방향족 니트로화합물을 이용한 은 나노입자 표면 양전하 유도 및 올레핀 촉진수송 분리막에의 응용

Abstract

Facilitated olefin transport membranes were prepared with silver nanoparticles (Ag NPs) activated by noble electron acceptors, 1,2-dinitrobenzene (DNB) and 3,4-dinitrotoluene (DNT), and subsequently dispersed in a poly(vinyl pyrrolidone) (PVP) matrix. The positive charge inducement on the surface of Ag NPs with an electron acceptor is necessary to obtain high separation performance for propylene/propane mixtures. The noble electron acceptors containing two strong electronegative groups, -NO2, developed in this study show extremely high separation performance, the mixed-gas selectivity up to 172. Herein, the effects of the noble electron acceptor DNB and DNT on 1) surface positive charge inducement of Ag NPs, 2) the separation performances of facilitated olefin transport membranes, and 3) their correlation are investigated. In Part 1, the cryogenic distillation process, a conventional olefin/paraffin separation process, was first introduced. The needs for alternatives to the distillation process were proposed by emphasizing the importance of olefin separation in petrochemical industries and the merits of membrane separation technology. Subsequently, the concept of facilitated olefin transport was introduced to overcome the problems associated with membrane technologies using conventional polymeric materials. Previous researches on facilitated olefin transport membranes for separation of olefin/paraffin mixtures were reviewed and the importance of carriers in the facilitated transport membranes, particularly the function of electron acceptors, was highlighted. In Part 2, it was described that the surface positive charge inducement by nitroaromatic compounds, a noble electron acceptor, in facilitated olefin transport membranes. Ag NPs synthesized with PVP and AgBF4 were characterized by ultraviolet-visible (UV-vis) spectroscopy and transmission electron microscopy (TEM). DNB and DNT were used to induce the partial positive charge on the Ag NPs surface. The surface of positively charged Ag NPs was characterized by measuring the binding energy of Ag atom with X-ray photoelectron spectroscopy (XPS). The separation performance through the facilitated olefin separation membranes containing positively charged Ag NPs dispersed in PVP was characterized in terms of the pure propylene gas permeance and the mixed-gas selectivity of propylene/propane. Additionally, it is found that the separation performances have a close linear correlation with the positive charge density on the Ag NPs determined by the amount of electron acceptor. Finally, it is demonstrated that two noble electron acceptors are very effective in the inducement of partial positive charge on the surface of Ag NPs and the improvement in the separation performance for olefin/paraffin mixtures.