Nanoporous carbons have become a material of interest in many applications such as electrochemical double layer capacitors (supercapacitors). Supercapacitors are being studied for their potential in storing electrical energy storage from intermittent sources and in use as power sources that can be charged rapidly. However, a lack of understanding of the charge storage mechanism within a supercapacitor makes it difficult to optimize them. Two components of this challenge are the difficulties in experimentally characterizing the sub-nanoporous structure of carbon electrode materials and the electrical performance of the supercapacitors. This work provides a means to accurately characterize the porous structure of sub-nanoporus carbon materials and identifies the current limitations in characterizing the electrical performance of a supercapacitor cell. Future work may focus on the relationship between the sub-nano porous structure of the carbon electrode and the capacitance of supercapacitors, and on the elucidation of charge storage mechanisms.

Nanoporous carbons have become a material of interest in many applications such as electrochemical double layer capacitors (supercapacitors). Supercapacitors are being studied for their potential in storing electrical energy storage from intermittent sources and in use as power sources that can be charged rapidly. However, a lack of understanding of the charge storage mechanism within a supercapacitor makes it difficult to optimize them. Two components of this challenge are the difficulties in experimentally characterizing the sub-nanoporous structure of carbon electrode materials and the electrical performance of the supercapacitors. This work provides a means to accurately characterize the porous structure of sub-nanoporus carbon materials and identifies the current limitations in characterizing the electrical performance of a supercapacitor cell. Future work may focus on the relationship between the sub-nano porous structure of the carbon electrode and the capacitance of supercapacitors, and on the elucidation of charge storage mechanisms.

Mesoporous γ-Al2O3 is one of the most widely used catalyst supports for commercial catalytic applications. The performance of a catalyst strongly depends on the combination of textural, chemical and physical properties of the support. Pore size is essential since each catalytic system requires a unique pore size for optimal catalyst loading, diffusion and selectivity. In addition, high surface area and large pore volume usually result in higher catalyst loading, which increases the number of catalytic reaction sites and decreases reaction time. Therefore, determination of surface area and porosity of porous supports is critical for the successful design and optimization of a catalyst support. Moreover, it is important to produce supports with good thermal stability since pore collapsing due to sintering at high temperatures often results in catalyst deactivation. In addition, the ability to control the acidity of the catalyst enables us to design desirable acid sites to optimize product selectivity, activity, and stability in different catalytic applications. This dissertation presents a simple, one-pot, solvent-deficient method to synthesize thermally stable silica-doped alumina (SDA) without using templates. The XRD (X-ray diffraction), HTXRD (high temperature X-ray diffraction), SS NMR (solid state nuclear magnetic resonance), TEM (transmission electron microscopy), TGA(thermogravimetric analysis), and N2 adosorption techniques are used to characterize the structures of the synthesized SDAs and understand the origin of increased thermal stability. The obtained SDAs have a surface area of 160 m2/g, pore volume of 0.99 cm3/g, and a bimodal pore size distribution of 23 and 52 nm after calcination at 1100◦C. Compared to a commercial SDA, the surface area, pore volume, and pore diameter of synthesized SDAs are higher by 46%, 155%, and 94%, respectively. A split-plot fractional-factorial experimental design is also used to obtain a useful mathematical model for the control of textural properties of SDAs with a reduced cost and number of experiments. The proposed quantitative models can predict optimal conditions to produce SDAs with high surface areas greater than 250 m2/g, large pore volume greater than 1 cm3/g, and large (40-60 nm) or medium (16-19 nm) pore diameters. In my approach, I control acid sites formation by altering preparation variables in the synthesis method such as Si/Al ratio and calcination temperatures. The total acidity concentration (Brønsted and Lewis) of the synthesized SDAs are determined using ammonia temperatured program, pyridine fourier transform infrared spectroscopy (FTIR), and MAS NMR. The total acidity concentration is increased by introducing a higher mole ratio of Si to Al. In addition, the total acidity concentration is decreased by increasing calcination temperature while maintaining high surface area, large porosity, and thermal stability of γ-alumina support. I also present an optimized synthesis of various aluminum alkoxides (aluminum n-hexyloxide (AH), aluminum phenoxide (APh) and aluminum isopropoxide (AIP)) with high yields (90-95%). One mole of aluminum is reacted with excess alcohol in the presence of 0.1 mole % mercuric chloride catalyst. The synthesized aluminum alkoxides are used as starting materials to produce high surface area alumina catalyst supports. Aluminum alkoxides and nano aluminas are analyzed by 1H NMR, 13C NMR, 27Al NMR, gCOSY (2D nuclear magnetic resonance spectroscopy), IR (infrared spectroscopy), XRD, ICP (induced coupled plasma), and elemental analysis.

Self-activation is a process that takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon. The pyrolytic gases from the biomass contain CO2 and H2O, which can be used as activating agents. As two common methods, both of physical activation using CO2 and chemical activation using ZnCl2 introduce additional gas (CO2) or chemical (ZnCl2), in which the CO2 emission from the activation process or the zinc compound removal by acid from the follow-up process will cause environmental concerns. In comparison with these conventional activation processes, the self-activation process could avoid the cost of activating agents and is more environmentally friendly, since the exhaust gases (CO and H2) can be used as fuel or feedstock for the further synthesis in methanol production. In this research, many types of biomass were successfully converted into activated carbon through the self-activation process. An activation model was developed to describe the changes of specific surface area and pore volume during the activation. The relationships between the activating temperature, dwelling time, yield, specific surface area, and specific pore volume were detailed investigated. The highest specific surface area and pore volume of the biomass-derived activated carbon through the self-activation process were up to 2738 m2 g-1 and 2.209 cm3 g-1, respectively. Moreover, the applications of the activated carbons from the self-activation process have been studied, including lithium-ion battery (LIB) manufacturing, water cleaning, oil absorption, and electromagnetic interference (EMI) shielding.

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