Synthesis Of Sulfonic Carbon-bassed Solid Acid Catalysts And Its Catalytic Study Of Esterification

In traditional esterification process,liquid protonic acid such as sulfuric acid and hydrochloric acid are usually used to catalyze the esterification reaction.But this kind of catalyst belongs to the homogeneous catalyst.There are a lot of problems may occurred in the process of actual production such as large amount of waste water,corrosion of equipment and difficulties in separating the catalyst from product.This is contrary to the concept of green chemistry proposed by today's society.After more than half a century of research and development,the heterogeneous solid acid catalyst has attracted widespread attention,and there are new solid acid catalysts that have been developed and studied constantly.Since the carbon-based solid acid catalyst was first prepared,catalysts prepared from some carbohydrate or industrial waste to various sources of carbon carrier have been widely studied.Carbon-based solid acid catalyst has become a hot subject of research in the field of catalysis with low production cost,simple preparation process and higher catalytic activity.This paper targets on the synthesis of carbon-based solid acid catalyst and explores the structure-activity relationship of catalyst by using different acids to provide catalytic active center and different organic compounds as carbon carrier to synthesize a series of sulfonic carbon-based solid acid catalysts and exploring their catalytic performances in esterification reaction.?1?For the catalyst,the active center is the key of the catalyst.Firstly,through regulating the mass ratio of glucose to sodium hydrogen sulfate,we got a series of catalysts with the stable acidic compound salt monohydrate sodium bisulfate as catalytic active center and carbon carrier with glucose as the raw material.The catalysts were characterized by FT-IR,SEM,EDS,TGA,XPS and BET.The XPS proved that the active center SO₃H was successfully loaded on the carbon ball.Applying the catalysts in the esterification of oleic acid with methanol,the experimental results showed that the catalyst had good catalytic performance when the mass ratio of glucose to sodium hydrogen sulfate was 1:4.The conversion of oleic could reach 97.0%at 70 ^oC after 5 h.?2?The carbon carriers were synthesized by the hydrothermal reaction of terephthalaldehyde and four similar organics m-aminophenol,o-aminophenol,m-Nitrophenol and o-Nitrophenol,and then the carbon carriers were sulfonated by Chlorosulfonic acid.The catalysts were analyzed by FT-IR,SEM,EDS,TGA,XPS and BET.The total acid densities of the catalyst T-m-N-SO₃H prepared by m-Nitrophenol was the highest,reaching 2.17 mmol g^-1.From the performance tests,these catalysts were proved to be high catalytic activities for the conversion of oleic acid,and both could reach over 94.7%.Thereinto,the highest conversion of oleic acid was 97.8%with the catalyst T-m-N-SO₃H.And the conversion of the catalyst maintained 84.7%after 4 cycles,and total acid densities still kept 1.66 mmol g^-1.?3?Considering the effect of specific surface area on catalytic performance,organic polymer carbonation with higher specific surface area was used to prepare carbon carrier.We selected two solvents deionized water and 1,4-dioxane in the hydrothermal reaction of phloroglucinol and terephthalaldehyde,and then sulfonated by Chlorosulfonic acid.Characterization methods of FT-IR,SEM,EDS,TGA,XPS and BET etc.were carried out to have a comprehensive insight into the catalyst.It showed that the catalyst prepared by 1,4-dioxane as solvent had higher specific surface area?92.4 m²/g?and total acid densities(2.26mmol g^-1)and had better catalytic performance.The conversion of oleic acid attained 98.2%when the reaction temperature was 70 ^oC,reaction time was 4 h,the Me OH/OA molar ratio was10:1,2.0 wt.%of catalyst.Moreover,the conversion of oleic acid was still up to 84.3%when the catalyst was reused for the fifth time.?4?Through the hydrothermal reaction with pyrrole,indoles and terephthalaldehyde,two carbon solid catalysts TP-SO₃H and TI-SO₃H were prepared.Characterization methods of FT-IR,SEM,EDS,TGA,XPS and BET were carried out to conduct a comprehensive inspection.According to the characterization analysis,the TP-SO₃H had a neat spherical structure and specific surface area reached 70.9 m²/g.The catalysts were used in the preparation of esterification reaction of methyl oleate and the results showed that TP-SO₃H had better catalytic activity.The conversion of oleic acid was 98.8%under the reaction conditions of 10:1 molar ratio Me OH/OA,2.0 wt.%of catalyst and reacting at 60 ^oC for 4 h.And the conversion of oleic acid was still 87.4%,respectively,after recycling the catalyst six times.Overall,the catalyst TP-SO₃H showed excellent catalytic activity and stability.