反气相色谱法研究前沥青烯的表面性质

Determination of preasphaltene surface properties by inverse gas chromatography

采用反气相色谱法表征前沥青烯的表面性质,测定了其表面色散自由能及酸碱常数,并基于极性探针的吸附,得到极性探针在前沥青烯表面的极性吸附自由能?G^(sp)和极性吸附焓?H^(sp)。结果显示,温度在60~100℃范围内,前沥青烯的表面色散自由能随着温度的升高而逐渐减小。前沥青烯表面的酸常数K_a为0.91,碱常数K_b为2.98,K_b/K_a=3.27。由此可知,前沥青烯为两性偏碱性材料。

The surface properties of the preasphaltene were characterized by inverse gas chromatography, surface dispersion free energy and acid-base constant. The polar adsorption free energy △G（sp） and the polar adsorption enthalpy △H（sp） of the polar probe on the surface of the preasphaltene were obtained by the adsorption of polar probes. The results show that the surface free energy of the preasphaltene decreases with the increase of the temperature at the temperature of 60—100℃. The acid constant Ka is equal to 0.91, the base constant Kb is equal to 2.98, and Kb/Ka is equal to 3.27. It can be seen that the surface of the preasphaltene is amphoteric, and the alkaline effect is stronger than acid effect.