Ultramicroporous silicon nitride ceramics for CO₂ capture

Abstract

Carbon dioxide (CO 2 ) capture is regarded as one of the biggest challenges of the 21st century; therefore, intense research effort has been dedicated in the area of developing new materials for efficient CO 2 capture. Here, we report high CO 2 capture capacity in the low region of applied CO 2 pressures observed with ultramicroporous silicon nitride-based material. The latter is synthesized by a facile one-step NH 3 -assisted thermolysis of a polysilazane. Our newly developed material for CO 2 capture has the following outstanding properties: (i) one of the highest CO 2 capture capacities per surface area of micropores, with a CO 2 uptake of 2.35 mmol g À1 at 273 K and 1 bar (ii) a low isosteric heat of adsorption (27.6 kJ mol À1 ), which is independent from the fractional surface coverage of CO 2 . Furthermore, we demonstrate that the pore size plays a crucial role in elevating the CO 2 adsorption capacity, surpassing the effect of Brunauer-Emmett-Teller specific surface area.

Microporosity and CO2 Capture Properties of Amorphous Silicon Oxynitride Derived from Novel Polyalkoxysilsesquiazanes

“…Generally, CO 2 capture capacity strongly depends on the SSA of solid sorbent [15,44,45] and, in this study, evaluation was performed on the three samples; 550 °C-pyrolyzed DHNpOSZ having the highest SSA together with 600 °C- and 800 °C-pyrolyzed EtOSZ samples.…”

“…Then, the CO 2 adsorption capacities evaluated at the CO 2 partial pressure, p / p 0 = 1.0 were plotted as a function of SSA of the ROSZ-derived Si–O–N samples (Figure 12). In this figure, CO 2 adsorption capacities at 1 bar of some representative solid sorbents reported in the scientific literature [15,30,31,32,33,34,35,45] were also plotted. At 0 °C, the CO 2 capture capacity of the 800 °C-pyrolyzed EtOSZ (Et(800)) was 2.16 mmol·g −1 at SSA = 279 m 2 ·g − 1 .…”

“…Micro and mesoporous structure formation through the polymer-derived ceramics (PDCs) [1,2] route has received increasing attention as an attractive ceramic processing route to develop gas separation membranes, gas sorbents and catalysts with thermally and/or chemically stable amorphous systems such as silicon nitride [3], silicon carbide [4,5,6,7,8,9], silicon carbonitride (Si–C–N) [10], silicon oxycarbide (Si–O–C) [11,12,13], silicon oxycarbonitride (Si–O–C–N) [14,15,16] and other quaternary Si–M–C–N (M=B, [17,18], Ni [19]). During the crosslinking and subsequent high-temperature pyrolysis of polymer precursors, by-product gases such as CO 2 , CH 4 , NH 3 and H 2 were detected, and the microporosity in the amorphous PDCs could be assigned to the release of the small gaseous species formed in-situ [14,15,16,20,21,22,23].…”

“…During the crosslinking and subsequent high-temperature pyrolysis of polymer precursors, by-product gases such as CO 2 , CH 4 , NH 3 and H 2 were detected, and the microporosity in the amorphous PDCs could be assigned to the release of the small gaseous species formed in-situ [14,15,16,20,21,22,23]. …”

“…Schitco et al also reported that polymer-derived ultra-microporous amorphous silicon nitride showed an excellent CO 2 capture capacity of 2.35 mmol·g −1 at 0 °C and 1 bar. They proposed that the observed high CO 2 storage capacities could be achieved in materials with high amount of ultra-micropore volume [15]. …”