Synthesis and characterization of polymer derived porous carbons for gas adsorption, storage and separation

The space trapped between the carbon micro structures shapes irregular pores and microchannels with average pore width below 2 nm. This native porosity acts as molecular sieve being able to separate small molecules of different sizes and shapes. Because of their inherent porosity, relatively high surface area and small pore size, nanoporous carbons (NPCs) are extensively used in gas adsorption, gas membrane separations, shape selective catalysis and synthesis of battery and double layer capacitors.;This thesis resides in the area of development of novel carbon based adsorbents with enhanced adsorption properties. Briefly, novel approaches were implemented to characterize adsorption properties of the carbons at low and high pressures.;One major task in characterizing porous materials is to determine their textural properties including pore size, surface area and pore volume. This becomes a more complicated issue when the pores are of irregular shapes and spectroscopic methods like X-ray diffraction (XRD) cannot be effective. Gas adsorption is the simplest and yet the most general approach to evaluate porosity. Adsorption of a small probe molecule at different gas concentrations is analyzed to elucidate the pore size distribution, surface area and accessible pore volume of a porous material. Herein, we used methyl chloride as the probe molecule and proposed a novel pressure control algorithm to accelerate gas adsorption dynamics. Fast adsorption of methyl chloride combined with the pressure control method resulted in an accelerated gas porosimetry method that could characterize micro and mesopores of a porous sample near room temperature, under subatmospheric pressure and in a single run.;We continued studying gas adsorption properties of porous materials, by developing a high pressure gas adsorption instrument. Many industrial and commercial applications of gas adsorption, catalysis and separation operate at elevated pressures and temperatures. This chapter explains design and implementation of a custom-made automated high pressure gas adsorption instrument. The accuracy of the instrument is analyzed using error analysis.;The fifth chapter concerns about the energetics of adsorption of light gases in microporous carbons. Adsorption properties of light gases, including H2, N2, O2, Ar, CO, CH4, CO2 SF6, NH3, and SO2 were studied on microporous carbon materials near room temperature. Ono-Kondo model and coordinates were used to decouple surface interactions, the forces between adsorbed molecules and adsorbent surface, and lateral interactions, the forces between the adsorbed molecules in the adsorbed phase. The effect of adsorption uptake on the energy loss of the adsorbed molecules was also investigated for H2 adsorption at 4 K on PFA-derived carbons using Inelastic Neutron Scaterring.;Chapter six studies the effect of textural properties of the porous carbon materials on CO2 adsorption uptake. Different polymers including, polyfurfuryl alcohol, polyaniline, polypyrrole and poly (N-methyl aniline -- para-phenylene diamine) were synthesized and characterized. Accurately tuning the pore size and lowering the pore volume enhanced CO2 adsorption both on gravimetric and volumetric basis. KOH activated PFA-derived carbon with only pore volume of 0.6 cc/g exhibited gravimetric uptakes as high as the preeminent adsorbents at 1 bar and room temperature. In addition, they exhibited 20% improvement in the volumetric adsorption capacity.;Chapter seven studies adsorption of NH3 on functionalized microporous and mesoporous carbon materials. We synthesized acid functionalized carbon materials with different pore sizes. The materials were carefully studies using XPS and DRIFTs analysis before and after functionalization. Effect of surface functionalization on NH3 adsorption was invoked using high pressure gas adsorption.