Polycyclotrimers of 1,4-diethynylbenzene, 2,6-diethynylnaphthalene, and 2,6-diethynylanthracene: Preparation and gas adsorption properties

摘要

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/Ph_4Sn catalyst. Brunauer-Emmett-Teller (BET) surface area, microporosity, and maximum sorption capacity for H_2 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 S_(BET) = 1299 m~2 g ~(-1), a_(H2) = 1.26 wt% (100 kPa, 77 K), and a_(CO2) = 10.8 wt% (100 kPa, 273 K). N_2 isotherms show that adsorption/desorption hysteresis occurs already at low equilibrium pressures. CO_2 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.