Synthesis Of Porous Carbon Based Solid Acid And Catalytic Activities

Catalysts play an important role in the modern chemical industry and are widely used in the manufacture of petrochemical and chemical products.The most used acid catalyst in modern chemical industry is sulfuric acid,which are annually consumed more than 15 million tons.However,sulfuric acid is difficult to separate from the homogeneous reaction system,which need tedious,complex and energy-consumed post-treatment.Solid acids are easy to be separated from the reaction system,but the traditional solid acid suffered from low acidity,poor thermal stability.Carbon based solid acids own the advantages of simple preparation process,which characterized by high acid density and structure stability etc.The traditional carbon based solid acids from glucose and sucrose as raw material,often give low surface area,resulting in a difficulty in contact of large molecule reactants and acidic sites on solid acid.Improving the carbon based solid acids surface area has become a research hotspot.Porous carbon material preparation methods are applied for the preparation of carbon based solid acids.However,the expensive mesoporous template is needed.Moreover,the template removal process is quite complex.In order to solve the above problems,this thesis presents green economic method to synthesize porous carbon based solid acid materials.The main research contents include:?1?Glucose is used as carbon source and NaHCO₃ as pore forming agent.NaHCO₃was used to decompose CO₂ and carbonate,which form pores in the incomplete carbonized intermediates.Then,sulfonation is applied to prepare porous carbon based solid acids.The influence of the ratio of glucose and NaHCO₃ on carbonization process was studied by thermogravimetry.The carbonization conditions were screened.The porous carbon was sulfonated to give the carbon based solid acids.The structure and morphology of the solid acids were characterized by elemental analysis,infrared spectrum,specific surface area and scanning electron microscope.Under the optimum conditions,the specific surface of the material can reach 98 m²/g,which shows high catalytic activity for esterification and acetalization with the average conversion over90%.?2?The porous carbon based solid acid was synthesized by ZnCl₂ molten salt template method.The high specific surface carbon based solid acid materials are prepared by the incomplete carbonization and sulfonation of glucose,sucrose and starch under the condition of zinc chloride molten salt carbonization.The influence of the experimental conditions on the structure and acidity of the solid acid are analyzed by orthogonal analysis,and the conditions for the synthesis of solid acid are optimized.On this basis,the material structure is characterized,with extremely high BET surface area of 1440 m²/g,which is highly active for biodiesel synthesis.?3?Magnetic porous carbon based solid acid materials have been prepared by hydrothermal carbonization.Chitosan was used as carbon source.Chitosan was used to protect the magnetic core and hydroxyethyl sulfonic acid as the center of acid.After the ultrasonic dispersion of magnetic iron oxide,a core-shell structure carbon based solid acid was prepared by one-step hydrothermal carbonization.The magnetic core gives the material magnetism and can be separated by a simple magnetic field.The acid center on the carbon shell is easy to contact with the reactants to improve the reaction activity.The synthetic carbon based solid acid acid value is 1.1 mmol/g,and the specific surface area of BET is 116 m²/g higher than that of the traditional carbon based solid acid.The materials have high catalytic activity for the alkylation of hydrophobic benzene and 1-dodecene,which greatly expanded the application range of carbon based solid acid.