新型硅胶复合干燥剂的制备与性能研究

Research on a Modified Silica Gel-Based Desiccant

针对普通硅胶吸水率不高、单一组分改性硅胶再生温度相对较高的缺陷,运用氯化钙和氯化镁复合改性硅胶,制备新型干燥剂。通过测定复合硅胶的差示扫描量热曲线(DSC)和热重分析(TG)曲线,考察复合硅胶的吸水性能、再生性能和对水的脱附活化能的影响。研究表明:在室温饱和湿度下,用浓度均为0.25 mol L 1的氯化钙和氯化镁复合改性硅胶的吸水量约为未改性硅胶相应值的2倍,吸湿速率提高3.5倍以上。复合干燥剂的再生温度比改性前低了10℃,脱附活化能数值小,再生6次后再生率依然高达92%左右,且基本不再变化。

Since the water absorption ratio of ordinary silica gel is not high and the regeneration temperature of silica gel modified separately by magnesium chloride or calcium chloride only is relatively high, a new kind desiccant was prepared by modifying the silica gel with magnesium chloride and calcium chloride simultaneously. Using the solution with appropriate ratio of magnesium chloride and calcium chloride as the composite modifier could make the modified silica gel have high hydroscopic ability and lower regeneration temperature. The differential scanning calorimeter （DSC） and the thermogravimetric analysis （TG） were used to investigate the regeneration performance, hydroscopic properties and the corresponding activation energies of water desorption of the silica gel modified by the composite modifier. The results show that, at the saturated air humidity corresponding to room temperature and using solution composed of 0.25 mol.L-1 of calcium chloride and 0.25 mol.L-1 of magnesium chloride as modifier, the water absorption capacity of the modified silica gel enhances greatly, which is about 2 times higher than that of the unmodified silica gel. Besides, the water absorption rate of the modified silica gel is significantly improved by 3.5 times and more, and its regeneration temperature is about 10℃ lower. Moreover, after recycling for 6 times, the regeneration ratio of the modified silica gel is still as high as 92%, and which remains unchanged basically.