| Using Shengli lignite as raw material, coal based solid acid catalyst was prepared by one-step carbonization sulfonation of concentrated sulfuric acid. The catalytic activity of the catalyst was evaluated by esterification reaction of oleic acid and methanol.The effects of solid-liquid ratio, sulfonation temperature and sulfonation time on the catalytic activity were investigated.The coal based solid acid catalyst was characterized by IR, EA, BET, SEM, XRD and TG-DTG.The results showed that when the sulfonation temperature was 110℃, the sulfonation time was 90 min, and the solid-liquid ratio was 1∶17, the coal based solid acid catalyst had the best catalytic activity with the esterification rate reaching 93.50%.The catalyst was amorphous carbon structure with low graphitization degree. The sulfonic acid group was successfully bonded to the carbon-based support. The catalyst had abundant oxygen-containing functional groups, and its surface presented dense pore structure, which was mainly mesoporous. The catalyst had better thermal stability below 140℃. After repeated use for 5 times, the esterification rate was 57.21%. |
