Photocatalytic Oxidation Of Glucose By Supported Metal Porphyrazine And Bi-based Catalyst

Since the 21st century,a sustained rise in the price of petrochemical products,at the same time,the production processof them leads to the serious problems of environmental pollution.The widespread biomass in nature can be efficient way into a green material fuel or high value-added chemicals so based on the research of this transformation is of great significance for sustainable development of the society.Glucose is an important biomass and is the most widely distributed monosaccharide in nature.It can be obtained directly from plants or indirectly through hydrolysis of cellulose and lignin.Catalysts play an important role in the process of converting glucose into a variety of high value-added chemicals.Therefore,how to design green and efficient catalysts for this conversion process has become an important research direction in the field of biomass refining.Herein,three highly active composite photocatalysts,SnO₂/Fe Pz（SBu）₈,Bi₂WO₆/Co Pz（SBu）₈ and Bi_3.64Mo_0.36O_6.55/Bi,were designed and prepared for the selective photocatalytic oxidation of glucose in water system.Using oxygen in the air as oxidant,these catalysts have good catalytic effect on the photocatalytic oxidation of glucose under room temperature and pressure.The specific work includes the following:A composite photocatalyst SnO₂/Fe Pz（SBu）₈ was prepared by supporting Fe Pz（SBu）₈ on the surface of SnO₂.The photocatalytic activity of SnO₂/Fe Pz（SBu）₈ was better than that of SnO₂ alone.Under the optimized experimental conditions,the total selectivity of organic acids（gluconic acid,gluconic acid and formic acid）in the glucose oxidation products reached52.2%when the conversion rate of glucose was 34.2%.The main reactive oxygen species in the photocatalytic process are h⁺and O₂·^-by quenching experiment and ESR experiment.According to the relevant experimental results,it is speculated that there are two parallel reactions in the glucose photocatalytic oxidation system:one is that C1 atom of glucose is affected by reactive oxygen species to produce gluconic acid;The other is that the C6 atom of glucose is reacted by the reactive oxygen species to produce glucuronic acid,which is then oxidized to gluconediate.Using Bi₂WO₆/Co Pz（SBu）₈ as photocatalyst and oxygen in the air as oxygen source,the glucose was transformed into formic acid and arabinose under the optimized experimental conditions.The conversion rate was 45.3%and the total selectivity was 99.0%.O₂·^-,H⁺and¹O₂ were reactive oxygen species and played an important role in the catalytic system by quenching experiments and ESR experiments.Based on the analysis of the types of oxidation products,it is speculated that the oxidation of glucose in this system is through the process of breaking the carbon-carbon bond between C1 and C2 to produce arabinose and formic acid.When Bi_3.64Mo_0.36O_6.55 and Bi were used as photocatalyst to catalyze the oxidation of glucose,oxygen in the air as oxygen source,and the glucose was transformed into formic acid and arabinose by visible light irradiation under optimized experimental conditions.The conversion rate was 57.3%,and the total selectivity was 73.5%.If only Bi_3.64Mo_0.36O_6.55 is used as photocatalyst,the product will be mineralized and the total selectivity become lower.When the metal Bi was introduced,the total selectivity of the product increased by about 2times while maintaining the glucose conversion rate.O₂·^-,H⁺and ¹O₂ were reactive oxygen species and played an important role in the catalytic system by quenching experiments and ESR experiments.Through the analysis of the types of oxidation products,it is speculated that the oxidation mechanism of glucose in this system is the same as that of Bi₂WO₆/Co Pz（SBu）₈,which is the process of forming arabinose and formic acid through the broken carbon-carbon bond between C1 and C2.