Synthesis Of Phosphorus-Doped Porous Carbon And Its Application In Selective Oxidation Of Alcohols

Selective oxidation of alcohols is a common and important class of chemical reactions in organic synthesis and is widely used in medicine,chemicals,dyes and other fields.At present,the use of more extensive research is precious metal or composite metal catalysts.However,the kind of catalyst is expensive to produce and tends to have reduced catalytic activity during the reaction,due to carbon deposition,high-temperature sintering,etc.Therefore,the development of sustainable,high-efficiency carbon-based non-metallic catalysts has become one of the current research hotspots.Porous carbon materials are widely used in catalysis,adsorption,and hydrogen storage because of their large specific surface area,abundant channels,high chemical stability,good electrical conductivity and thermal conductivity.Heteroatoms act as electron donors to intervene in porous carbon-carbon structures,causing them to be distorted in space and causing local structural defects.At the same time,they change the distribution of electrons,increasing the adsorption capacity for oxygen and other gases which increase the catalytic activity of porous carbon material.In this paper,a kind of phosphorus-doped porous carbon was prepared by one-step microwave method,taking glucose as the carbon source and phosphoric acid as the phosphorus source.The preparation process was optimized,considering the doping ratio,microwave irradiation duration,microwave irradiation power,intermittent/continuous microwave modes.Firstly,SEM,FT-IR,Raman,XRD,XPS and TG characterization methods were used to study the apparent morphology,elemental composition and structural order of the catalyst samples.The results showed that phosphorus was successfully doped into the carbon structure.The content of phosphorus and oxygen functional groups in the material was abundant,and it had certain structural defects.It is an amorphous carbon material with good thermal stability.Subsequently,different types-of catalysts were used in the selective oxidation of benzyl alcohol.The reaction conditions were as follows:2mmol of benzyl alcohol,150mg of catalyst samples,10mL of 1,4-dioxane as solvent,and reaction at 120? for 12h.The catalytic activity of the sample was determined by comparing the conversion and selectivity of the reaction.The results showed that the preparation conditions were as follows:the phosphoric acid-glucose doping ratio 5:1,intermittent microwave 3min(microwave min,intermittent 2min,microwave 2min),middle and high fire stalls that had the highest catalytic activity,and the conversion rate of benzyl alcohol was 23.6%,and benzaldehyde selectivity was above 99%.Based on the research above,phosphorus-doped porous carbon was applied to the oxidation reaction of phenolic hydroxybenzyl alcohol compound-vanillol.The results showed that phosphorus-doped porous carbon catalyzed the oxidation of vanillyl alcohol to vanillin without affecting the phenolic hydroxyl group.The factors affecting the oxidation reaction of vanillyl alcohol were investigated from the aspects of reaction temperature,catalyst loading,reaction solvent and reaction time.The reaction conditions were 1 mmol vanillyl alcohol,the amount of catalyst M5 was 350mg,the reaction temperature was 120? that the conversion of vanillyl alcohol was highest(96.00%)and the vanillin selectivity was more than 99%when the reaction was carried out for 6h.The above experimental results show that the phosphorous doped porous carbon obtained by microwave irradiation has high specificity and catalytic activity.