Catalytic Oxidation Of No At Room Temperature By Activated Carbon Fibers And Modified Activated Carbon Fibers.

With rapid development of economy, the exhaust of nitrogen oxides has been increasing continuously. Nitrogen oxides are air pollutants which are harmful to the human and animals. Activated carbon fibers (ACFs) can used for NO_x removal because of their large specific surface areas, abundant micropores, rich surface functional groups and catalytic sites.The removal of NO is the focus of the study for NO accounts for 90% of NO_x. NO can be hardly physically adsorbed by activated carbon fibers at room temperature. However, NO can be easily removed by oxidation to NO₂. Therefore, the key point of my study is catalytic oxidation and removal of NO by activated carbon fibers and modified activated carbon fibers.Four pitch-based ACFs with different specific surface areas were used for catalytic oxidation of NO with a concentration of 50ppm at room temperature. ACFs were characterized with nitrogen adsorption, Raman and IR analysis. The results show that the breakthrough time of NO₂ increase with increasing the specific surface areas and total pore volumes while the catalytic oxidation abilities for NO are related to pore distribution and graphite microcrystalline size. Micropores and smaller graphite microcrystalline lead to higher catalytic oxidation abilities. Different kinds of ACFs'catalytic oxidation abilities have been studied. The pitch-based ACFs show higher catalytic capabilities than PAN-based ACFs partly because of their different surface functional groups.Pitch-based activated carbon fibers loaded with manganese oxides were used for the catalytic oxidation and removal of NO in air at room temperature. XPS analysis was used to characterize modified ACFs. The results show that when the ACFs are modified by loading manganese oxides, the breakthrough time of NO₂ is reduced but the catalytic oxidation abilities for NO are remarkably promoted. The optimal loading percent is 3.64%, which can make the oxidation rate of A15 for NO increase from 20.1% to 30.6%. Manganous acetate is deposited on pre-oxidized ACFs by solution dipping method. Then ACFs are calcined in the atmosphere of N2. Modified ACFs can chemically adsorbed NO in ambient condition. XPS analysis shows that manganese nitrates may be created during that progress. Besides, nitric acid is better than hydrogen dioxide for pre-oxidization of ACFs.