The Regulation Of Carbon Material Surface Active Groups And Their Application In Styrene Selective Oxidation Reaction

There are a variety of carbon materials widely used because of their abundant physical and chemical properties.To obtain good performance,carbon materials are modified,for example,specific substances are added to obtain specific functional groups in hydrothermal synthesis reaction of carbohydrates.The activated carbon has crystallites with graphite structure,which are defective and therefore heteroatoms can be introduced.Effective catalysts can be produced by taking advantage of the two properties of carbon materials and modifying them.Catalytic performance was evaluated by the reaction of hydrogen peroxide selective oxidation styrene.The experiment contents are summarized as follows.Firstly,litchi-like monodisperse carbon spheres from hydrothermal synthesis of D-glucose and acrylic acid which are rich in carboxyl and mesoporous exchanged Fe³⁺with ferric nitrate solution in order to get Fe/C?A?.The dosage of acrylic acid,the concentration of ferric nitrate solution,exchange temperature and time were observed,and the dosage of catalyst,the volume ratio of hydrogen peroxide to styrene,the type of solvent,temperature and time were investigated using the optimal catalyst.The mechanism of free radical was proved to exist in the oxidation reaction.The surface morphology and functional groups of Fe/C?A?indicated that Fe³⁺was highly dispersed on the surface of the catalyst and reacted with carboxyl by using XRD,SEM,BET,TG-DTA,FT-IR and XPS characterization.Fe as the main active site catalyzed hydrogen peroxide to decompose free radicals which oxidated styrene to benzaldehyde.Secondly,activated carbon?AC?and p-toluenesulfonic acid?p-TsOH?were put in the reaction of hydrogen peroxide selective oxidation styrene.The dosage of AC and p-TsOH,the temperature of reaction,the molar ratio of hydrogen peroxide to styrene were investigated.AC and p-TsOH had synergistic effect to make the oxidation reaction get a high conversion of styrene,while these two could not promote the reaction solely.It was certified by acid simulation using non-sulfur inorganic acid that the acidity of p-TsOH did not play a significant role in catalytic process.Using sulfonated AC instead of p-TsOH and AC proved that the-SO3H played a major role.The FT-IR characterization showed that there were acid oxygen containing groups on AC soaked by nitric acid?HAC?,and the thermal treatment in H2 or N2 could remove them.The fluorescence spectra characterized that HACH2 and HACN2 were more efficient on the decomposition of hydrogen peroxide to free radicals,therefore enhanced the conversion of styrene and reduced the selectivity to benzaldehyde.The reaction mechanism was confirmed by free radical inhibitor,experiment data and characterization results,which was p-TsOH reacted with H2O2 by a non-radical process generating peroxysulfonic acid to oxidize styrene while the AC assisted the p-TsOH/H2O2 system by a radical process.