Synthesis Of Carbon-based Solid Acid Catalysts And Their Catalytic Performance

Carbon-based solid acid catalyst is a green and efficient catalyst derived from sulfonation of the incomplete carbonization of polycyclic aromatic hydrocarbon.This catalyst can keep the advantages of carbon materials,such as large specific surface area and excellent hydrothermal stability.In this work,several carbon-based solid acid catalysts have been prepared by different methods.The esterification of oleic acid with methanol was employed as a probe reaction to explore the catalytic performance of the as-made catalysts.The chemical and physical characteristics of the obtained catalysts were characterized by N₂adsorption,transmission electron microscope,X-ray powder diffractomter,X-ray photoelectronspectroscope,Ramanspectrometer,Fouriertransforminfrared spectrophotometer,element analysis and so on.The main contents and results are as following.?1?A carbon-based solid acid catalyst was simply prepared from petroleum coke by chemical activation and subsequent sulfonation.The relationships between the structure and function of the solid acid catalyst were investigated by regulating activation temperature.The solid acid catalyst activated at 800 ^oC exhibits the most excellent catalytic activity,which is attributed to its large surface area(851 m² g^-1)and high acid density(1.04 mmol g^-1).At the optimized conditions?80 ^oC for 6 h?,high conversion?89.5%?was achieved and no distinct activity drop was observed after five recycles.?2?SO₃H-functionalized monodispersed hollow carbon/silica spheres?HS/C-SO₃H?with primary mesopores were prepared with polystyrene as template and p-toluenesulfonic acid?TsOH?as a carbon precursor and-SO₃H source simultaneously.The well-defined hollow architecture and enhanced active site accessibility of HS/C-SO₃H guarantee the highest catalytic performance compared with the catalysts prepared by activation of TsOH deposited on the ordered mesoporous silicas SBA-15 and MCM-41.At the optimized conditions,i.e.80^oC for 5 h,high conversion?96.9%?was achieved and no distinct activity drop was observed after 5 recycles.?3?Sulfonic acid?-SO₃H?functionalized carbon/silica solid acid catalysts with high strong acid site density and large pore size were prepared by hydrothermal treatment of the mixture of glucose,p-toluenesulfonic acid?TsOH?and ordered mesoporous silica SBA-15.In the hydrothermal process,glucose underwent dehydration and decomposition reactions,then the intermediates polymerized to polymers as well as alkylated with TsOH to link-SO₃H to the polymers.These carbon-rich polymers were partically carbonized at low temperature to fabricate the carbon/silica solid acid catalysts.As a solid acid catalyst in the esterification of oleic acid with methanol,the catalyst prepared from 0.5 g SBA-15,2 g glucose and 3 g TsOH?SBA-15/C-2-3?exhibits the best catalytic activity.At the optimized conditions,i.e.80 ^oC for5 h,high oleic acid conversion?97.5%?was achieved and no ditinct activity drop was observed after 5 cycles.