Synthesis Of Hydrogen Peroxide From H₂/O₂ With Flat Type Dielectric Barrier Discharge

Hydrogen peroxide(H₂O₂) is a versatile and environmentally friendly oxidizing agent. The direct synthesis of H₂O₂ via non-equilibrum plasma,which is characterized by simple operation process,high concentration and ultra high purity of the product,provides a promising alternative route for H₂O₂ production.Based on our previous works,the synthesis of H₂O₂ from hydrogen and oxygen using self-designed self-cooling flat type double dielectric barrier discharge(DDBD) reactor have been carried out in this study.The following main results were obtained:1.The material nature and the thickness of dielectric barrier,the gas gap distance,the material nature of electrodes,cooling-water temperature and discharge frequency all have significant effects on H₂O₂ synthesis.The energy efficiency,O₂ conversion and H₂O₂ yield were enhanced by using the reactor with appropriate thickness of quartz dielectric barrier, narrow gas gap distance and copper electrode.The increase of discharge frequency and decrease of cooling-water temperature at a certain extent also favored the improvement of O₂ conversion,H₂O₂ selectivity and energy efficiency.The direct synthesis of H₂O₂ has achieved 69.1%O₂ conversion,60.1%H₂O₂ selectivity,41.5%H₂O₂ yield and 9.5 gH₂O₂/kWh energy efficiency under the conditions of copper electrode,the quartz dielectric barrier,the thickness of barrier 2.0 mm,the gas gap distance 2.0 mm,the discharge frequency 13 kHz,the reactor input power 11.8 W,the H₂/O₂ mixture flow rate 118 ml/min,the O₂ concentration in the H₂/O₂ mixture 2.5%and the cooling-water temperature 5℃.2.The scale-up synthesis of H₂O₂ from H₂/O₂ via a dielectric barrier discharge at ambient conditions was studied by using a reactor consisting of multiple parallel fiat type DBD reactors.Varying the number of reactors had no significant effect on discharge mode and reaction mechanism.The H₂O₂ selectivity is the same as that of the single reactor.When the input power increased from 13.5 to 38.6 W,the residence time 2 s and the discharge frequency 13 kHz,the H₂O₂ productivity increased from 3.4 mmol/h to 8.8 mmol/h in the scale-up reactor.With the scale-up reactor,the energy efficiency was obtained as high as 9.5 gH₂O₂/k Wh.When residence time of the scale-up reactor is the same as that of the single flat type DBD reactor,the application of scale-up reactor can obtain higher H₂O₂ productivity and higher energy efficiency than the application of the single flat type DBD reactor.