碱土金属改性MCM-41对氨气吸附高温性能的影响

Effect of alkaline earth metals modification on high temperature adsorption performance of MCM-41 to ammonia

采用浸渍法制备不同负载量的碱土金属(MgCl_(2)、CaBr_(2)、MgBr_(2))改性MCM-41复合材料,并在固定床上进行氨气吸附实验。利用XRD、BET、SEM、TEM对吸附剂进行表征,并研究其在高温下对氨气吸附的性能。结果表明,氨气吸附容量随着温度的升高而减小,随着金属盐负载量的增大先增加后减少。对于MgCl_(2)和MgBr_(2)复合材料,负载量为40%时吸附容量达到最大;CaBr_(2)负载量为30%时达到最高,但其在300℃时吸附容量呈上升趋势。镁盐比钙盐吸附氨气的能力强,溴化物比氯化物的吸附容量大,MgBr2配位数比其他盐大。200℃下负载量为40%的MgBr_(2)/MCM-41吸附量最高。

Alkaline earth metal salts(MgCl_(2),CaBr_(2),MgBr_(2))are loaded on MCM-41 at various amount via impregnation method.Adsorption experiments of ammonia by the modified MCM-41 are carried out in a fixed bed column.The modified MCM-41 is characterized by XRD,BET,SEM/TEM,and its adsorption performance to ammonia at high temperature is studied.It is shown that its adsorption capacity to ammonia decreases with the increasing temperature,but increases firstly and decreases then with the increasing content of metal salts.For the adsorbents modified by MgCl_(2) and MgBr_(2),the maximum adsorption capacity to ammonia is achieved at a loading amount of 40%.The optimal loading content for CaBr_(2) is 30%,but the adsorption capacity of CaBr_(2) modified MCM-41 to ammonia can increase at 300℃.Generally,magnesium salts have stronger adsorption ability to ammonia than calcium salts,while bromides have larger adsorption capacity than chlorides.MgBr_(2) has a larger coordination number than other salts.At 200℃,the highest adsorption capacity has been achieved by MgBr_(2)/MCM-41 with 40% loading content.