Polycyclotrimers of 1,4-Diethynylbenzene, 2,6-Diethynylnaphthalene, and 2,6-Diethynylanthracene: Preparation and Gas Adsorption Properties
Abstract
Hyperbranched partly cross-linked polycyclotrimers of 1,4-diethynylbenzene, 2,6-diethynylnaphthalene, and 2,6-diethynylanthracene, Pc(1,4-DEB), Pc(2,6-DEN), and Pc(2,6-DEA), respectively, are prepared using TaCl 5/Ph4Sn catalyst. Brunauer-Emmett-Teller (BET) surface area, microporosity, and maximum sorption capacity for H2 and CO 2 decrease in the order of decreasing relative content of branching points in polycyclotrimers Pc(1,4-DEB) > Pc(2,6-DEN) > Pc(2,6-DEA), the highest values for Pc(1,4-DEB) being SBET = 1299 m2 g -1, aH2 = 1.26 wt% (100 kPa, 77 K), and aCO2 = 10.8 wt% (100 kPa, 273 K).
N2 isotherms show that adsorption/desorption hysteresis occurs already at low equilibrium pressures. CO2 isotherms show that the time allotted to the measurement influences both the maximum adsorption capacity and the hysteresis upon desorption.
Hyperbranched partly cross-linked diethynylarene based polycyclotrimers are prepared and their surface area, microporosity, and sorption capacity for hydrogen and carbon dioxide are reported to decrease in the order of decreasing relative content of branching points. Adsorption/desorption behavior and dependence of adsorption capacities on the time allotted to the measurements are discussed.