五种香气分子在活性炭上的脱附活化能

Desorption activation energy of aromas molecules of five types on activated carbon adsorbent

运用程序升温脱附(TPD)实验测定了大马酮、γ-壬内酯、乙基香兰素、乙基麦芽酚和乙酸乙酯五种香气分子在活性炭上的脱附曲线,并根据实验数据计算香气分子在活性炭上的脱附活化能.结合香气分子的偶极矩和分子直径大小,分析五种香气分子的物性对其与活性炭表面吸附作用力(脱附活化能)强弱关系.结果表明:大马酮、γ-壬内酯、乙基香兰素、乙基麦芽酚和乙酸乙酯在活性炭表面上的脱附活化能分别是57.92,55.70,54.41,49.83和46.34kJ/mol.香气分子的直径大小顺序为:大马酮>γ-壬内酯>乙基香兰素>乙基麦芽酚>乙酸乙酯,分子直径大者,其脱附活化能就更大.而这些香气分子的极性大小与其脱附活化能未能形成单调增大或单调减少的关系,表明其极性大小在这些分子与活性炭表面的形成相互结合力方面未能起到主导作用.

The desorption activation energy of aroma molecules of five types, such as damascenone, γ- nonalactone, ethyl vanillin, ethyl matol and ethyl acetate on activated carbons were investigated by temperature program desorption （TPD） technique. The TPD experiments were conducted to analyze the interaction of an aroma molecule with adsorbent, and estimate desorption activation energy of these five kinds of aroma molecules on the activated carbons. The effects of the diameter and the polarity of aroma molecules on desorption activation energy were discussed. The results showed that the aroma molecules＇ diameter has significant influence on desorption activation energies. The desorption activation energies of damascenone, γ-nonalactone, ethyl vanillin, ethyl matol and ethyl acetate are separately 57.92, 55.70, 54.41, 49.83 and 46.34 kJ/mol, which decreases with a decrease in aroma molecules＇ diameter. The polarity of aroma molecules cannot pay a dominant role in interaction between these molecule and carbon surface.