用乙酸制备羟基化硅胶以增强虽CO_(2)吸附性能

Preparation of Hydroxylated Silica Gel Using Acetic Acid to Enhance CO_(2)Adsorption Performance

采用乙酸改性制备了一种羟基化硅胶吸附剂,用于CO,静态吸附研究以揭示乙酸浓度和吸附温度对羟基化硅胶吸附性能的影响。通过乙酸羟基化硅胶,可以清理硅胶孔道并暴露其表面羟基,提高CO_(2)平衡吸附量,其中最佳乙酸浓度为6mol/L,最佳吸附温度为20℃,吸附压力0.62MPa下吸附剂SG-C-6平衡吸附量可达35.88mL/g,比硅胶高14.3%。选取吸附剂SG-C-6进行了重复使用性能实验,经过10次的重复使用后,平衡吸附量仍达到34.44mL/g,比第1次吸附下降了4%,这表明其具有较好的重复使用性能。构建了羟基化硅胶的分子结构模型,从原子层面揭示了羟基化吸附剂的羟基化机理。结果表明,羟基化后的吸附剂的吸附能由-5.87 kJ/mol降至一10.57kJ/mol,更低的吸附能表明羟基化后的吸附剂对CO_(2)的亲和性更高,进一步证明了乙酸羟基化硅胶的必要性。

A hydroxylated silica gel adsorbent was prepared by acetic acid modification for CO_(2)static adsorption research to reveal the effects of acetic acid concentration and adsorption temperature on the adsorption performance of hydroxylated silica gel.By hydroxylating silica gel with acetic acid,the pores of the silica gel can be cleaned and the surface hydroxyl groups can be exposed,improving the CO_(2)equilibrium adsorption capacity.Under the conditions of optimal acetic acid concentration of 6 mol/L,optimal adsorption temperature of 20℃,and adsorption pressure of 0.62 MPa,the equilibrium adsorption capacity of adsorbent SG-C-6 can reach 35.88 mL/g,which is 14.3%higher than that of silica gel.The adsorbent SG-C-6 was selected for repeated use performance experiments.After 10 repeated uses,the equilibrium adsorption capacity still reached 34.44 mL/g,which was 4%lower than that of the first adsorption,indicating that it had good reusability.A molecular structure model of hydroxylated silica gel was constructed,revealing the hydroxylation mechanism of hydroxylated adsorbents at the atomic level.The results show that the adsorption energy of the hydroxylated adsorbent decreases from-5.87 kJ/mol to-10.57 kJ/mol,and the lower adsorption energy indicates that the affinity of the hydroxylated adsorbent to CO_(2)is higher,which further proves the necessity of hydroxylation of silica gel with acetic acid.