改性活性炭吸附脱除二氧化碳中微量乙烷

Removal of trace amount of C_2H_6 from CO_2 by modified activated carbon

我国对食品级二氧化碳要求较高,在其生产过程中乙烷的脱除是难点。文章首先考察了市售的不同吸附剂,包括Y型、X型、A型等分子筛类,椰壳和煤基活性炭以及吸附树脂等吸附剂对CO2中微量C2H6的吸附效果,之后考察了不同浓度盐酸酸改性与氢氧化钠碱改性、双氧水氧化改性、氨水还原改性等改性条件对吸附剂吸附性能的影响。研究表明,具有高比表面积、丰富微孔和适量中孔结构的活性炭更有益于二氧化碳中微量乙烷的吸附;浓度为1%的盐酸溶液浸渍活性炭3 h后,能增强其对CO2中微量C2H6的吸附能力;浓度3%、浸渍时间6 h为氢氧化钠碱溶液改性活性炭的最佳条件;弱氧化剂双氧水改性能略微提高活性炭对二氧化碳中乙烷的吸附能力,弱还原剂氨水改性对吸附效果无明显影响。

The removal of ethane from food grade CO2 is the bottleneck in the food processing industry. This paper focused on finding the best adsorbent for ethane from food grade CO2 and the optimal adsorption conditions. Molecular sieve,coconut shell,coal based activated carbon,and resin were selected as the adsorbents. Activated carbon was modified using different methods,including hydrochloric acid and sodium hydroxide alkali modification,hydrogen peroxide oxidizing and ammonia reduction modification. The results showed that the activated carbon performed well in the CO2 adsorption at high specific surface area,abundance of micropores,a few mesopores and nonpolar surface were more conductive to the adsorption performance. Activated carbon impregnated by a concentration of 1% hydrochloric acid solution for 3 hours adsorbed more ethane. The best condition of the alkaline solution modified activated carbon was at the concentration of 3% and absorption time of 6 hours. Weak oxidant modification could increase the ethane adsorption to a certain point. Weak reducer modification did not have obvious effects on the adsorption of ethane.