硅胶的改性及其脱碳性能研究

Research on modification and decarburization of silica gel

以稀硫酸溶液改性硅胶得到新型CO2吸附剂,探究CO2静态吸附中的硫酸浓度(cs)与吸附温度(ts)对CO2吸附量的影响,得到了最佳制备与吸附条件:cs=0.125 mol·L-1,ts=20℃,此时CO2吸附量可达33.97 mL·g-1.为了揭示吸附剂结构性能,分析吸附机制,对吸附剂进行氮气吸脱附分析,结果表明:硫酸溶液的浸渍具有清理硅胶孔道与扩孔效果,增加硅胶表面羟基数量,对CO2吸附有着良好的促进作用,有效地降低了CO2吸附温度的敏感性.通过对改性吸附剂的吸附动力学与热力学分析,表明改性后吸附剂符合准二级动力学模型.在不同吸附温度下,热力学参数保持VH0>0,VS0>0,VG0<0,表明反应是吸热过程,改性后吸附反应正向自发,温度越高自发进程越快.另外吸附剂重复使用10次后仍然保持较高吸附效果,为工业应用提供了可能.

Silica gel was modified by dilute sulfuric acid to prepare new carbon dioxide adsorbents,and the influence of sulfuric acid concentration(cs)and temperature(ts)of CO2 adsorption was investigated.The optimum preparation and adsorption conditions were obtained:cs=0.125 mol·L-1,ts=20℃.At this point,the adsorption capacity of CO2 reached to 33.97 mL·g-1.To reveal the influence mechanism between structural properties and adsorption amount of modified adsorbent,the adsorbent was analyzed by nitrogen adsorption and desorption.It was indicated that,due to the immersion of sulfuric acid,silica gel channels were cleaned,and numerous hydroxyl groups were increased,which promoted the adsorption of CO2 and reduced the sensitivity of adsorption temperature.The adsorption kinetics and thermodynamics of the modified adsorbent showed that the modified adsorbent conformed to the quasi-second-order kinetic model.At different adsorption temperatures,due to VH0>0,VS0>0,and VG0<0,the reaction was endothermic and the adsorption reaction was forward spontaneous after modification.The spontaneous process was to speed up via high temperature.After repeated for 10 times,the adsorption effect remained high,which provided the possibility for industrial application.