Preparation Of Benzoxazine-based Carbon Materials And Catalytic Oxidation Of 2-methylnaphthalene To 2-menaphthoquinone

2-Monaphthoquinone is an important chemical intermediate,which is mainly used in the fields of medicine and feed additives.At present,2-menaquinone is mainly obtained by oxidizing 2-methylnaphthalene with sulfuric acid/chromic anhydride,which has serious environmental pollution.This research focuses on the application of carbon materials in the field of catalysis,and intends to explore a method for the carbon materials to catalyze the oxidation of 2-methylnaphthalene to prepare 2-menaquinone.In this paper,benzoxazine was used as the precursor,and the hard template method was used to successfully prepare different heteroatom-doped carbon materials by using the molecular design of benzoxazine;In the experiment,acetic acid/hydrogen peroxide was used as the reaction system to investigate the catalytic performance of the carbon material for the oxidation of 2-methylnaphthalene to 2-menaquinone in this system;In addition,the carbon material was modified to explore the influence of the catalytic material's own properties on the catalytic ability.The main research contents are as follows:The nitrogen doped carbon material?NCM?was prepared with aniline-type benzoxazine as carbon precursor and SBA-15 as template.The carbon material was tested by SEM,TEM,XRD,N₂ adsorption/desorption,and XPS.The test results of SEM and TEM have shown that the carbon material successfully copied the worm-like ordered mesoporous structure of the template.The specific surface area of the carbon material measured by N₂ adsorption/desorption was 670.04 m²/g,the average pore diameter was 6.1 nm,the pore volume was 1.02 cm³/g.The results of XPS have proved that the nitrogen element was successfully doped into the carbon material.There are two forms of nitrogen atoms,pyridine nitrogen and graphite nitrogen,in the carbon material.The content of the nitrogen element is 4.95%.The presence of pyridine nitrogen increases the surface defects of the carbon material.Make carbon materials have higher catalytic activity.On the basis of previous experiments,the effects of five factors including the reaction temperature,reaction time,acetic acid,H₂O₂,and raw materials on the oxidation reaction were investigated.Firstly,the experiment has designed an orthogonal test with 5 factors and 4 levels to conduct preliminary screening of the reaction conditions,and then investigated each factor by the single factor method.The optimal reaction conditions were obtained by optimizing the reaction conditions:reaction temperature:83°C,reaction time:5 h,mass ratio of acetic acid to 2-methylnaphthalene:33:1,mass ratio of H₂O₂ to2-methylnaphthalene:10:1,mass ratio of raw materials to catalyst:4:1.The yield under the optimal conditions was 65.8%.The experiment explored the effect of activation modification on the catalytic performance of carbon materials.The results have shown that the specific surface area of carbon materials has been greatly increased after activation,and the specific surface area has increased to 1621.43 m²/g.The experimental results have shown that the increase of the specific surface area promotes the reaction and reduces reaction time.In order to further explore the effect of nitrogen/sulfur double doping on the catalytic performance of carbon materials,this paper employs thiourea-type benzoxazine as the precursor and SBA-15 as a template to prepare N/S double-doped mesoporous carbon materials?NSCM?.The N/S double-doped mesoporous carbon material was subjected to the same characterization test as the nitrogen doped carbon material,and the results showed that the N/S double-doped mesoporous carbon material and the nitrogen doped carbon material have the same structure,and the specific surface area is 886.19 m²/g,average pore diameter is 7.2 nm,pore volume is1.60 cm³/g,nitrogen and sulfur are successfully doped into the carbon material,nitrogen content is 19.16%,there are three types of nitrogen,respectively Pyridine nitrogen,pyrrole nitrogen,and graphitic nitrogen.The sulfur content is 1%,and the existing forms are S 2p3/2 and S 2p1/2 of the thiophene sulfur C-S bond,and the C-SO_X-C bond.The sulfur element and higher nitrogen element content makes N/S double-doped mesoporous carbon materials have better catalytic performance.The same experimental scheme as NCM catalyst was used to investigate the catalytic performance.The optimal conditions obtained are reaction time:4 h,reaction temperature:85°C,mass ratio of acetic acid to 2-methylnaphthalene:26:1,mass ratio of H₂O₂ to 2-methylnaphthalene:8:1,mass ratio of raw materials to catalyst:3:1.The yield under the optimal conditions was 78.8%.In order to investigate the effect of pore structure on the catalytic performance of carbon materials,hydrothermal method was used to prepare template with different pore sizes,and carbon materials were prepared by hard template method.Its catalytic performance has a greater impact.With the increase of the pore diameter of the carbon material,the catalytic performance of the carbon material shows a tendency of rising first and then decreasing.