Preparation And Catalytic Performance Of A Carbon-based Solid Acid Catalyst With High Specific Surface Area By An Aryl Diazonium Salt Reduction Process

Carbon base solid acid material is currently the research focus in the field of catalysts. in order to make up the deficiency of sulphonated carbon solid acid material,need a carbon carrier with stable structure, high spicific surface and low cost, and the carbon carrier have high-density SO3H in its surface with covalent bond way. We think activated carbon is a more appropriate carbon carrier. If the activated carbon can be efficiently combined with sulfonic acid in covalent bond way, they are expected to get new solid acid catalyst with steady structure, low cost and high catalytic activity.In the experiment, a carbon-based solid acid catalyst was synthesized by sulfonating activated carbon in the diazonium salt reduction process.In order to comprehensive analysis of the composition,morphology,microstructure,BET surface area and pore size distribution of the carbon-based solid acid catalyst,various methods were taken to characterize the catalyst.We studied the catalytic activity used in different length of carbon chain of fatty acids with ethanol in esterification reactions and examined the activity of solid acid catalyst by esterification rate.The catalytic properties were compared with that of commercial solid acid catalysts.The activated carbon of coal was raw material in the experiment which had a specific surface area of 751 m2g^-1. we can known the results by elemental analysis and general acid density measuring result: before and after of the sulfonating ,S content of activated carbon were raised from 0.26 mmol g^-1 to 0.90 mmolg^-1 ,S content increased 0.64 mmolg^-1 in the sulfonating; the total acid density of activated carbon were raised from 0.3 mmolg^-1 to 1.01 0.3 mmolg^-1, acid density increased 0.71 mmolg^-1 in the sulfonating. this shows that the increase of S content and acid density were matched. XPS analysis further confirmed the state of being of S element in the solid acid catalyst;The TGA result showed that carbon-based solid acid catalyst has good thermal stability under 250℃.The BET result showed that the surface area and pore volume of the carbon materials decrease from 751 m2g^-1 and 0.47 cm³ g^-1 to 602 m2g^-1 and 0.38 cm³g^-1, suggesting that a little part of pore space has been occupied by the grafted SO3H group. The pore diameter does not change during sulfonation, This also suggests that carbon materials of microstructure has not changed much during sulfonation.We can see from this , the activated carbon were very suitable for catalyst carriers because of high mechanical strength, good thermal stability and high spicific surface.In order to investigate the catalytic activity of solid acid catalyst AC - PhSO3H,it was used in three different length of carbon chain of fatty acids in the esterification reaction,such as : acetic acid,hexanoic acid and decanoic acid. The catalytic properties were compared with that of commercial solid acid catalysts, Nafion NR50 and Amberlyst^-15. In the esterification of acetic acid , When solid acid catalyst were added 0.2 g, reaction 2h, esterification rate reached 36.8%,it has reached higher catalytic effect compared with foreign language document. The advantage of our carbon-based solid acid catalyst can be more evidently displayed in the esterification of decanoic acid,the decanoic acid conversion with AC- PhSO3H (52%) is much higher than that with Amberlyst-15 (36%) and with Nafion (17%) after 10 h of reaction.