Oxygen Reduction To Produce Hydrogen Peroxide Coupled With The Selective Oxidation Of Organic Compounds

As an environmentally friendly oxidant,hydrogen peroxide is widely used in organic synthesis,wastewater treatment,sanitation and disinfection.At present,hydrogen peroxide is mainly synthesized by the anthraquinone oxidation-reduction method,which not only has high energy consumption and complicated equipment,but also generates a lot of waste.Electrocatalytic oxygen reduction to produce hydrogen peroxide takes oxygen（air）as a raw material and electricity as an energy source to directly obtain hydrogen peroxide in one step,which is a promising alternative way.However,the concentration of electrosynthetic hydrogen peroxide is usually not high,and separation and concentration are difficult.In addition,due to the strong oxiditive properties of hydrogen peroxide,its storage and transportation are dangerous.If the electrosynthetic hydrogen peroxide can be used in situ for the selective oxidation of organics,the purification,separation,storage,and transportation of hydrogen peroxide can be avoided,and the equipment investment and operation cost can also be reduced.Based on this,this paper has carried out the following two tasks:（1）The feasibility of the selective oxidation of organics coupled with oxygen reduction to produce hydrogen peroxide in the membrane electrode reactor was studied.The reactor consists of an anode chamber,a cathode chamber and an organic catalyst chamber.The cathode chamber contains an anion exchange membrane coated with a carbon catalyst,and the anode chamber contains a cation exchange membrane coated with Pt/C or Ir O₂/C.The organic catalyst is located in the middle,filled with titanium silicon molecular sieve（TS-1）.During operation,oxygen（air）is introduced into the cathode chamber to generate OOH^-,and hydrogen or water is introduced into the anode to be oxidized to H⁺,which enters the intermediate organic catalytic chamber through the corresponding anion and cation exchange membranes to form H₂O₂,which further reacts with organic substrate catalyzed by TS-1.The results show that when phenol is used as the organic substrate,the selectivity of catechol and hydroquinone can reach94.68%（conversion rate 10.32%）,and the total Faraday efficiency（FE）is 30.25%.The coupling of oxygen reduction and benzyl alcohol oxidation,cyclohexanone ammoximation,furfural oxidation and other reactions were further studied,and high product selectivity and Faraday efficiency were also obtained.At the same time,when the anode reaction was replaced by direct electrooxidation of furfural,the FE of the paired synthesis of furoic acid reached 132.79%.（2）A dual-functional catalyst TS-1@Co-N-C that simultaneously catalyzes the reduction of oxygen to produce hydrogen peroxide and the oxidation of organics was prepared.Firstly,a layer of polymerized dopamine is coated on the titanium silicon molecular sieve（TS-1）,and then dopamine’s N is coordinated with Co²⁺to form a bifunctional catalyst with uniform Ly dispersed Co after pyroysis.The effects of pyrolysis temperature,polymerization time,and the ratio of each component on the catalysis performance in the reduction of O₂to H₂O₂.Under the optimal condition,the catalyst was used to realize the selective oxidation of phenol in the H-type electrolytic cell.The obtained selectivity of bisphenol is 99.45%,and the FE is 30.05%,both of which are higher than the mechanically mixed TS-1+Co-NC.