Preparation And Application Of Sulfonic Acid Ordered Mesoporous Carbon-based Solid Acid Catalyst

Sulfonic acid-based ordered mesoporous carbon-based solid acid catalysts have the advantages of high specific surface area and good thermal stability,and have become research hotspots.In this paper,different methods of sulfonic acid-based ordered mesoporous carbon-based solid acid catalysts were prepared,and their transesterification reactions for frying waste oil were studied to synthesize fatty acid methyl esters.The specific research content is as follows:?1?An ordered mesoporous carbon material?OMC?was synthesized by self-assembly using a soft template method using a nonionic surfactant P123 as a structure directing agent and a carbon precursor,and tetraethyl silicate?TEOS?as a silicon source.Then,two kinds of sulfonic acid-based ordered mesoporous carbon-based solid acid catalysts?OMC-SS,OMC-DS?were obtained by sulfonating them by sulfuric acid sulfonation method and diazonium salt coupling sulfonation method.Transmission electron microscope?TEM?and small angle X-ray diffraction?XRD?results show that OMC-800 exhibits a highly ordered mesoporous structure.Physical adsorption analysis showed a BET surface area of 713m²/g and an average pore diameter of 3.2nm.Raman and wide-angle XRD analysis showed that OMC-800synthesized at high carbonization temperature showed a higher degree of graphitization.The surface acid contents of OMC-SS and OMC-DS were3.3mmolH⁺/g and 3.1mmolH⁺/g,respectively.In addition,FTIR results also confirmed the existence of-SO₃H.The catalytic activities of OMC-SS and OMC-DS for transesterification showed that the maximum yields of fatty acid methyl esters?FAME?were 93.5%at a reaction temperature of 180°C,a reaction time of 6h,and a catalyst amount of 0.6g And 92%.?2?Using sucrose as the carbon source,block copolymer P123 as the surfactant,and TEOS as the silicon source,a hydrothermal ordered mesoporous carbon material?HOMC?was prepared by a low-temperature hydrothermal method,and then a low-temperature sulfuric acid sulfonation method was used.Coupled with the diazonium salt sulfonation method,two sulfonic acid hydrothermal ordered mesoporous carbon-based solid acid catalysts?HOMC-SS,HOMC-DS?were obtained.Transmission electron microscope?TEM?and small-angle X-ray diffraction?XRD?results show that HOMC exhibits a highly ordered mesoporous structure.Physical adsorption analysis showed that the BET surface area of HOMC was 112m²/g,and the average pore size was 11.0nm.The surface acid content of HOMC-SS and HOMC-DS was 5.9mmolH⁺/g and 5.4mmolH⁺/g,respectively.From the catalytic activity of OMC-SS and OMC-DS for transesterification reaction,the highest yield of fatty acid methyl ester?FAME?was obtained when the reaction temperature of OMC-SS was 180?,the reaction time was 5h,and the amount of catalyst was 0.6g95%,and the maximum yield of fatty acid methyl ester?FAME?is 92%when the reaction temperature is 180°C,the reaction time is 6h,and the amount of catalyst is0.6g.?3?SiO₂ microspheres are used as the core,and mesoporous molecular sieve?SBA-15?is wrapped on the outside to obtain a mesoporous material with a core-shell structure,named SiO₂@SBA-15,using it as a template and sucrose as a carbon source Mesoporous hollow carbon microspheres?MHCM?were prepared by the hard template method.Finally,two kinds of mesoporous hollow carbon-based solid acid catalysts?MHCM-SS,MHCM-DS?were obtained by sulfuric acid heating sulfonation method and diazonium salt coupling sulfonation method.TEM results showed that the hollow carbon microspheres were successfully formed.Physical adsorption analysis showed that MHCM has an area of 620m²/g and double-porous mesopores with pore sizes of 2.7nm and 3.4nm,respectively.The surface acid contents of MHCM-SS and MHCM-DS were 2.8mmolH⁺/g and 3.0mmolH⁺/g,respectively.In addition,FTIR results also confirmed the presence of-SO₃H.From the catalytic activity of MHCM-SS and MHCM-DS for the transesterification reaction,the highest yield of fatty acid methyl ester?FAME?was obtained when the reaction temperature of MHCM-SS was 180°C,the reaction time was 5h,and the amount of catalyst was 0.6g90%,and the maximum yield of fatty acid methyl ester?FAME?is 93%when the reaction temperature is 180°C,the reaction time is 6h,and the amount of catalyst is0.6g.