PNNL

Abstract

A previously class of porous coordination polymer (PCP) of formula [Cu(bpy-n)2(SiF6)] (bpy-1 = 4,4’-bipyridine; bpy-2 = 1,2-bis(4-pyridyl)ethene) has been studied to assess its selectivity towards CO2, CH4, N2 and H2O. Gas sorption measurements reveal that [Cu(bpy-1)2(SiF6)] exhibits the highest uptake for CO2 yet seen at 298K and 1atm by a PCP that does not contain open metal sites. Significantly, [Cu(bpy-1)2(SiF6)] does not exhibit particularly high uptake under the same conditions for CH4, N2, H2O and, presumably because of its lack of open metal sites. Consequently, at 298K and 1 atm [Cu(bpy-1)2(SiF6)] exhibits exceptional selectivity for CO2 over CH4 of ca. 10.5:1. [Cu(bpy-2)2(SiF6)] exhibits larger pores and surface area than [Cu(bpy-1)2(SiF6)] but retains relatively high selectivity for CO2 of ca. 8:1