NH₃-assisted synthesis of microporous silicon oxycarbonitride ceramics from preceramic polymers: a combined N₂and CO₂adsorption and small angle X-ray scattering study

Abstract

The NH3-assisted synthesis strategy from preceramic polymers provides tools to engineer the porosity of microporous SiCNO ceramics for potential applications in the fields of catalysis, gas adsorption and gas separation.

Ultramicroporous silicon nitride ceramics for CO2 capture

“…Ultramicropore volume (V ultra ) was calculated by applying the Dubinin-Astakhov (D-A) equation to the CO 2 adsorption isotherm at 273 K. Mean pore size (d) was estimated by the equation of Stoeckli for the characteristic adsorption potential between 20 and 42 kJ mol À1 , the latter being determined as well by D-A equation from the CO 2 isotherm at 273 K. For more details, please refer to our previous work. 34 High pressure CO 2 adsorption isotherms were recorded with an automated high-pressure volumetric sorption analyzer iSorb (Quantachrome Instruments, Boynton Beach, FL). Prior to the adsorption run, the void volume of the sample cell was determined in a blank cell measurement under given analyses conditions.…”

“…34 The porosity characteristics of HTT600NH are mentioned in Table I. In addition, micropores can be divided to ultramicropores (pores below 0.7 nm) and supermicropores (pores between 0.7 and 2 nm).…”

Formation of Micro and Mesoporous Amorphous Silica-Based Materials from Single Source Precursors

“…During the crosslinking and subsequent high-temperature pyrolysis under an inert atmosphere of polymer precursors, by-product gases such as CH 4 , NH 3 and H 2 were detected [5,22], and the microporosity in the polymer-derived non-oxide amorphous ceramics could be assigned to the release of the small gaseous species formed in-situ [8,22].…”

“…Recently, micro and mesoporous structure formations have been often discussed for the polymer-derived amorphous silicon nitride [7,8], silicon carbide [9][10][11][12][13][14], silicon carbonitride (Si-C-N) [15], silicon oxycarbide (Si-O-C) [16][17][18] and quaternary Si-M-C-N (M = B [19,20], Ni [21]). During the crosslinking and subsequent high-temperature pyrolysis under an inert atmosphere of polymer precursors, by-product gases such as CH 4 , NH 3 and H 2 were detected [5,22], and the microporosity in the polymer-derived non-oxide amorphous ceramics could be assigned to the release of the small gaseous species formed in-situ [8,22].…”

Polymer-derived amorphous silica-based inorganic–organic hybrids having alkoxy groups: intermediates for synthesizing microporous amorphous silica materials

“…4) 6) Perhydropolysilazane (PHPS) has been extensively studied as a carbon free polymer precursor, that is readily oxidized to yield pure silica with a high ceramic yield, either by pyrolysis in air, 7) or by exposure to aqueous ammonia vapour at room temperature. 8), 9) To date, micro-and meso-porous structures formation has been often discussed for the polymer-derived amorphous ceramics such as silicon nitride (Si N), 10), 11) silicon carbide (Si C), 12) 17) silicon carbonitride (Si C N), 18) quaternary Si M C N (M=B, 19), 20) Ni 21) ), silicon oxycarbide (SiOC), 22) 24) and silica (Si O). 7),25), 26) During the crosslinking and subsequent hightemperature pyrolysis of polymer precursors, by-product gases such as CH 4 , NH 3 and H 2 were detected, 5), 27) and the microporosity in the polymer-derived non-oxide amorphous ceramics could be assigned to the release of the small gaseous species formed in-situ.…”