Study On The Synthesis And Performance Of Metallic Iron-doped SBA-15 Mesoporous Molecular Sieve

As an important raw material in chemical industry,dihydroxybenzene is mainly used to synthesize hair dyes,preservatives and developers.The traditional methods of producing dihydroxybenzene have the problems of high energy consumption,serious environmental pollution and corrosion of production equipment.Therefore,this paper chooses hydrogen peroxide as oxidant to synthesize dihydroxybenzene with phenol in one step.This method has the characteristics of mild reaction conditions and products have no pollution to the environment.In order to develop a catalyst with high efficiency for this reaction,a series of mesoporous materials were prepared by hydrothermal method using pure silicon SBA-15mesoporous molecular sieve as carrier.The hydroxylation reaction products of phenol were analyzed by high performance liquid chromatography?HPLC?.The main contents are as follows:?1?Mesoporous?x?Fe-SBA-15 materials with different iron content were prepared by hydrothermal method using P123 as template and tetraethyl orthosilicate?TEOS?as inorganic silicon source.The materials were characterized by X-ray diffraction,N₂adsorption-desorption,transmission electron microscopy and infrared spectrum.The experimental results showed that?0.05?Fe-SBA-15 mesoporous materials exhibit good catalytic performance in phenol hydroxylation while maintaining ordered mesoporous structure and large specific surface area of SBA-15 mesoporous molecular sieve.?2?In the environment containing F^-,F^-can not only form fluorine complexes with transition metals,but also accelerate the hydrolysis rate of silicon source,which is propitious to the introduction of metallic iron into the framework of mesoporous materials.In this paper,the grafting rate of metal in zeolite was improved by adding hydrolytic reagent NH4F.The experimental results showed that proper addition of NH4F can not only ensure orderly mesoporous structure of the material,but also facilitate the entry of iron into the framework of molecular sieve.The?0.05?Fe-SBA-15?0.03?mesoporous materials prepared at the molar ratio of fluorosilicon to 0.03 exhibit high metal grafting rate and high catalytic performance in phenol hydroxylation.?3?With the best material?0.05?Fe-SBA-15?0.03?mesoporous molecular sieves as catalyst,the effects of reaction time,solvent type,reaction temperature,catalyst dosage and n?phenol?/n?H₂O₂?on the reaction were further discussed.The experimental results showed that deionized water was applied as the solvent,the reaction temperature was 60?,the catalyst was 100mg,reaction time was 3h,and n?phenol?/n?H₂O₂?was 1:1,the conversion of phenol was 40.72%,and the selectivity of dihydroxybenzene was 91.14%.The purpose of further improving the conversion of phenol and the selectivity of dihydroxybenzene in catalytic reaction was achieved.