SO₂ Adsorption Characteristics by Cellulose-Based Lyocell Activated Carbon Fiber on Cu Additive Effects

In this study, the Cu catalyst decorated with activated carbon fibers were prepared for improving SO2 adsorption properties. Flame retardant and heat treatments of Lyocell fibers were carried out to obtain carbon fibers with high yield. The prepared carbon fibers were activated by KOH solution for the high specific surface area and controlled pore size to improve SO2 adsorption properties. Copper nitrate was also used to introduce the Cu catalyst on the activated carbon fibers (ACFs), which can induce various reactions in the process; i) copper nitrate promotes the decomposition reaction of oxygen group on the carbon fiber and ii) oxygen radical is generated by the decomposition of copper oxide and nitrates to promote the activation reaction of carbon fibers. As a result, the micro and meso pores were formed and Cu catalysts evenly distributed on ACFs. By Cu-impregnation process, both the specific surface area and micropore volume of carbon fibers increased over 10% com- pared to those of ACFs only. Also, this resulted in an increase in SO2 adsorption capacity over 149% than that of using the raw ACF. The improvement in SO2 adsorption properties may be originated from the synergy effect of two properties; (i) the physical adsorption from micro, meso and specific surface area due to the transition metal catalyst effect appeared during Cu-impregnation process and ii) the chemical adsorption of SO2 gas promoted by the Cu catalyst on ACFs.