Preparation Of High Density Sulfonic Acid Carbon Microsphere-based Solid Acid And Its Application In Transesterification Of Waste Frying Oil

In this paper,we prepared carbon microspheres using hydrothermal method,and sulfonated hydrothermal carbon microspheres with a designed sulfonation method to prepare high density sulfonic acid carbon microsphere-based solid acid,and applied the solid acid to catalytic the transesterification reaction of waste oil and methanol.The specific research content is as follows:（1）In this chapter,carbon microspheres（CMs）were prepared by hydrothermal method with glucose as carbon source.Then,CMs were used as carrier and modified by oxidation,acylation and sulfonation/substitution reaction to prepare high-density sulfonic acid-based carbon microsphere solid acids.The characterization results of FT-IR,XPS,TG and elemental analysis showed that amino groups（-NH₂）were grafted on the surface of amidated carbon microspheres（ACMs）and sulfonic acid groups（-SO₃H）were grafted on the surface of sulfonated carbon microspheres（SCMs）;acid-base titration results showed that the surface acid density of SCMs was 11.3 mmol/g.The catalyst showed a good catalytic performance on the transesterification of waste frying oil.When the amount of catalyst added was 6 wt%,the reaction temperature was140°C and reaction time was 4 h,the highest yield of fatty acid methyl esters（FAMEs）was92.2%.The repeatability and stability of the catalyst were average.After four cycles under the optimal conditions,the FAMEs yield decreased from 92.2%to 65.9%.（2）In this chapter,we prepared high density sulfonic acid-based carbon microsphere solid acid starting with the preparation of high specific surface area hydrothermal carbon microspheres,and conducted the following research:Sn O₂/C composite microspheres were prepared by hydrothermal method under the effection of tartaric acid using glucose as the carbon source and tin chloride dihydrate（SnCl₂·2H₂O）as a porogen.Hydrochloric acid was used to remove Sn O₂to obtain porous carbon microspheres（PCMs）.Then,PCMs were used as carriers for oxidation,amidation and sulfonation to obtain high density sulfonic acid porous carbon microsphere-based solid acid catalysts（SPCMs）.The results showed that PCMs had a porous structure with a specific surface area of 50 m²/g and an average pore size of 12.1 nm;the surface acid density of the sulfonated SPCMs is 12.0 mmol/g.When the catalyst was used to catalyze the transesterification reaction of waste fat and methanol to prepare FAMEs.When the amount of catalyst added was 6wt%,the reaction temperature was 140°C and reaction time was 4 h,the optimal yield of FAMEs was 93.5%.The stability of the catalyst was relatively general.