Preparation And Catalytic Performance Evaluation Of Carbon-based Solid Acid Catalyst

Biodiesel as a green renewable energy, which could be mixed with diesel oil has many advantages, such as combustion superior performance, non-corrosive, environment-friendly, and it is a part of substitute for conventional fossil diesel. Transesterification method is currently the main method for biodiesel production. In industrialized production, liquid acid and alkali is usually used as the catalyst. Acid-catalyzed transesterification reaction, which is no special requirements for free fatty acids content and water content of the oil, it has high conversion rate. But the catalyst is badly corruption for equipments and can not be recycled.Carbon-baesd solid acid catalyst is a new type of solid acid catalyst. It has the characteristic of high catalytic efficiency, no corrosion of equipment and easily recycled.Considering from production costs, seeking one kind of cheap raw material has positive significance for the development of biodiesel.In this paper, using the easily available, cheap carbohydrate materials for biodiesel production as the research object, the esterification reaction of oleic acid ethanol was taken as the model reaction to investigate the impact of preparation parameters on the catalyst activity. Carbon-based solid acid catalyst which under the optimal preparation conditions applied for the prepraration of high-acid value of biodiesel.The results are as follows:1) Using glucose, sucrose, starch as raw materials, carbon-based solid acid catalyst was obtained by mixed with p-toluene sulfonic acid and carbonized at the appropriate temperature. The optimal conditions of P-SO3carbon-based solid acid catalyst preparation is that:the content of p-toluene sulfonic acid was28%of glucose weight, carbonization temperature140℃, carbonization time4h. The optimal conditions of Z-SO3carbon-based solid acid catalyst preparation is that:the amount of p-toluene sulfonic acid was28%of sucrose weight, carbonization temperature160℃, carbonization time4h. The optimal conditions of D-SO3carbon-based solid acid catalyst preparation is that:the amount of p-toluene sulfonic acid was28%of starch weight, carbonization temperature180℃, carbonization time4h.2) Using carboniazation-sulphonation method, carbon-based solid acid was prepared by starch as the raw material and98%sulfuric acid as the sulfonation reagents. The optimal conditions of H-SO3carbon-based solid acid catalyst preparation is that:carbonization temperature370℃, sulphonation tempreature150℃, sulphonation time4h。3) Carbon-based solid acid catalyst which was obtained by D-SO3and H-SO3method, it was used for the research on the effect of reducing acid of high-acid value oil. The performances of the catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), the rmogravimetrican analysis (TG) and scanning electron microscope. The results show that the catalyst has high surface area, all samples were amorphous chars, the obtained charmaterials had polycyclic aromatic rings with many oxygen-containing groups, and sulfonic acid groups substituted for active hydrogen atoms at the edge of aromatic rings to anchor in char framework. The experimental results show that the D-SO3carbon-baesd solid acid catalyst has higher catalytic activity and stability in esterification. The best reaction condition was as follows:methanol to oleic acid molar ratio8:1, the amount of carbon-based solid acid catalyst was6%of oleic acid weight, reaction temperature80℃, reaction time4h. D-SO3carbon-based solid acid catalyst which we had prepared had high catalytic efficiency, the conversioin rate of oleicacid was89.44%. After it was used for5times the conversioin rate of oleicacid was still above80%. H-SO3carbon-based solid acid catalyst which we had prepared at the optimal conditions, the conversioin rate of oleicacid was85.75%. After be used for5times the conversioin rate of oleicacid declined.But its catalytic activity can be regenerateg by sulfonation.Carbon-based solid acid catalyst has environmentally friendly, renewably and low-costly advantages, it also show higher catalytic performance in esterification.