(329j) Olefin Selectivity Enhancement Of Silver-Nitrate Impregnated Aluminosilica By Sodium Hydroxide Treatment On Substrate

Olefin/paraffin separation by distillation is an energy-intensive process because the boiling points of olefins are so close to those of their corresponding paraffins. Recently, olefin/paraffin separation using adsorption based on π-complexation has attracted much attention due to its high selectivity and reversible capacity. Silver nitrate (AgNO₃) is expected to be one of the most effective materials for olefin/paraffin separation because it showed strong affinity toward double bonds compared to saturated single bonds. To increase the number of effective adsorption sites for olefin in adsorbent, silver nitrate was distributed on high surface area substrates. One of the most effective adsorbent for the separation of olefin from paraffin was silver nitrate supported on aluminosilica. However, aluminosilica has various types of pores such as micropores (< 2nm), mesopores (2 -10 nm), and macropores (> 10 nm). Silver nitrate located inside micropores in aluminosilica is not expected to be active adsorption site for olefin because micropores might be barriers for olefin diffusion toward siliver nitrate. High surface area substrates with minimized portion of micropores or without micropores might be an ideal substrate for olefin separation adsorbents. To achieve this goal, this report investigated the effect of basic solution treatment on the selective removal of micropores in aluminosilica. Although total surface area of aluminosilica decreased after basic solution treatment, 1-butene selectivity to n-butane increased at optimized condition because micropores, which is the barrier for olefin adsorption, was removed. In addition to selectivity, desorption speed was also enhanced for the same reason.