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Description
Agricultural-waste biomass is investigated as a template to tailor high specific surface area (SSA) nano-structured carbonaceous materials. These precursor materials exhibit naturally well developed surface and hierarchical structural features which may find particular application in gas storage or adsorption and catalyst support technology. Novel biomass systems are utilized, particularly flax and crambe, as well as lentil, camelina and field pea. Chemical activation processing with KOH yielded activated carbon (AC) materials with SSA values from _125 to 900 m_g__. The products retained the shape of the natural stalk material, _2cm x 500_m cylinder and are amorphous as observed by XRD measurement. Conventional SPS processing is conducted under 40MPa load, resulting in a well integrated component with _5 m_g__ apparent SSA values. Simple powder deposition and conventional thermal synthesis techniques are applied to crambe AC for the generation of silicon carbide nano-wires (SiCNWs). The resulting unpurified samples showed reduced SSA from _900 to 100 m_g__ and did not exhibit significant structural enhancement. Large scale growth of SiCNWs is observed after loading with Si and pyrolysis; combinations of gas, solid and liquid processes are considered potential mechanisms for nanowire development. Spark plasma sintering processing under 40MPa load resulted in significant structural stability however SSA values of the unpurified SiC/C composites are also drastically reduced from 160 to 16 m_g__. A novel free-pressure-less spark plasma sintering (FPSPS) process is developed for the optimized production of a structurally integrated component, which exhibits retention of SSA values. Synthesis of SiC-agricultural-waste derived AC composite nano-materials is demonstrated through FPSPS processing at heating rates of 25 to 100 C up to 1600 C in vacuum. Improved macroscopic structural integrity is achieved through the development of SiC nanowire networks and preliminary SSA values of 69 m_g__ are measured, exhibiting potential application in catalyst support and other adsorption applications. Morphological evolution of unique nanostructure morphologies; nano-belts, nano-peapods as well as high aspect ratio, prismatic-shaped nanowires is observed, potentially catalyzed by naturally occurring impurity content from biomass sources. Conventional and free pressure-less SPS synthesis procedures are investigated and compared for generation of biomass-derived high SSA activated carbon (AC) materials. SSA values of _2000 m_g__ were obtained through this SPS activation technique, achieving nearly twice the apparent available surface compared with conventional processing attempts.
