Studies On Preparation And Properties Of Modified Activated Carbon Fiber And Adsorption Of SO₂ In The Atmosphere

The study on preparation and application of ACF for the problem of environmental contamination SO₂ in the atmosphere on the performance of catalyst poisoning of proton exchange membrane fuel cells(PEMFCs). To improve the adsorption properties of ACF, reactivation and remodification were carried out. The correlation between structures and adsorption properties were investigated by evaluation of adsorption properties. These basal data were very useful for how to enhance the adsorption properties of ACF and solve catalyst poisoning of proton exchange membrane fuel cells by the research of SO₂ adsorpted on ACF.Modified ACF was prepared from blending method combined with activation method under high temperature with Na₂CO₃,KI,Cu²⁺,Mn²⁺ four kinds modifiers. The influence of different factors on the reaction were studied, comparison of adsorption properties was preformed to confirm the optimal conditions of preparation. The optimum preparation conditions of Na₂CO₃ modifier were as follows: under 700℃protection by N₂, concentration of modifier 15%, activation time 40min, under the optimum conditions, the iodine number was 1144.91mg·g^-1, the basic groups content was 76.34mmol·g^-1, and the yield was 90.51%; the optimum preparation conditions of KI modifier were as follows: under 700℃protection by N₂, concentration of modifier 2%, activation time 60min, under the optimum conditions, the iodine number was 1167. 29mg·g^-1, the basic groups content was 61.14mmol·g^-1, and the yield was 90.4%; the optimum preparation conditions of Cu²⁺ modifier were as follows: under 700℃protection by N₂, concentration of modifiers 15%, activation time 40min, under the optimum conditions, the iodine number was 1185.2mg·g^-1, the basic groups content was 39.57mmol·g^-1, and the yield was 93.81%; the optimum preparation conditions of Mn²⁺ modifier were as follows: under 700℃protection by N₂, concentration of modifier 2%, activation time 80min, under the optimum conditions, the iodine number was 965.84mg·g^-1, the basic groups content was 82.99mmol·g^-1, and the yield was 89.74%.XRD, SEM, EDS indicated that modified ACF was turbostratic graphitelike crystallike structure, modifiers were well distributed, quantity of microporous and specific surface area was increased. Na weight percent of ACF-Na was 5.21%, atomic percent was 2.97%; K weight percent of ACF-I was 17.92%, atomic percent was 31.03%, I weight percent of ACF-I was 65.11%, atomic percent was 34.73%, Cu weight percent of ACF-Cu was 18.86%, atomic percent was 4.8%; Mn weight percent of ACF-Mn was 2.26%, atomic percent was 0.28%. ACF-Mn reactivated by Cu²⁺ modifier had better adsorption properties, the optimum preparation conditions were as follows: under 700℃protection by N₂, concentration of modifiers 10%, activation time 50min, under the optimum conditions, iodine number was 1605.36mg·g^-1, basic groups content was 119.86mmol·g^-1. XRD, SEM, EDS indicated that the particle size of Cu crystal from ACF-Mn-Cu50 is the biggest, the ordering degree and graphitization degree were both increased. Cu weight percent of ACF-Mn-Cu50 was 24.36%, atomic percent was 6.32%; Mn weight percent of it was 0.84%, atomic percent was 0.25%.The research of SO₂ adsorpted on ACF indicated that adsorbent ACF-Mn-Cu50 had a better adsorption effect than ACF-Mn, adsorption properties were increased by reactivation and remodification. The higher concentration of SO₂ in the atmosphere, the desulphurization effect is better. The optimum adsorption conditions were that, under the adsorption temperature 60℃, the rate of atmosphere Q1 was 0.3L·min^-1, Q2 was 0.4L·min^-1 respectively, the height of adsorption column was 20mm, the adsorption time was 3h. The dynamic analysis of SO₂ adsorpted on ACF concluded that dynamic process of SO₂ adsorpted on modified ACF coincidenced the second-order adsorption rate constants better.