Preparation Of Vinyl Tar Based Pitch To Develop Spherical Activated Carbon

A series of pitches were prepared using vinyl tar from YangZi Petrochemical as raw material, through vacuum distillation, or vacuum distillation combined with air-blowing. The structure and properties of pitches were characterized by FT-IR, TG analysis, GPC, elemental analysis, composition analysis. Additionally, the pitch with high softening point (>190℃) was also obtained to prepare pitch spheres, and then it was oxidation stabilized in air and carbonized in nitrogen. Their surface morphology was observed under SEM to explore the possibility of prepared spherical activated carbon using vinyl tar as raw material.Vinyl tar was vacuum-distilled at different temperature from 250 to 350℃for different from 1 to 9 h to prepare pitches with low ash content of 0.02%, and their softening point varying from 86℃to 161℃. When the distilled temperature is 325℃and distilled time is 3 h, the number average molecular weight of the pitch was maximum and the polydispersity index was minimum. When this pitch was compared with the reference pitch, it was found that their softening point, carbon yield, FT-IR properties, ash content, and the aromaticity were very similar. Therefore, the distilled temperature of 325℃and distilled time of 3 h is the optimal condition.Under the optimum experimental condition mentioned above, air-blowing method was used to modify the distilled pitch to further increase its molecular size and softening point, and then such pitches were employed to prepare pitch spheres. The results showed that the surface morphology of pitch spheres after oxidative stabilization remained smooth with the oxidation time increasing when the air-blowing temperature was 325℃. The optimum oxidation condition to prepare pitch spheres was 325℃for 14 h though the oxidation stabilization pitch spheres still reveal some tiny cracks.To decrease the cracks on the surface of pitch spheres, the pitch after air-blowing was distilled under vacuum again. The results showed that a short vacuum-distilled time was useful for improving the surface of pitch spheres after oxidative stabilization or even carbonization.