| The development of renewable energy online hydrogen production technology is an important development direction of hydrogen energy in the future.The advantages of microwave liquid phase discharge plasma alcohol reforming hydrogen production are greater alcohol energy density,higher liquid phase discharge mass transfer efficiency,and more convenient operation.The liquid phase discharge plasma technology is very suitable for online hydrogen production.However,the development history of this technology is relatively short.There are few studies on microwave liquid phase discharge plasma characteristics,hydrogen production mechanism and optimization methods,and these research contents are the key factors to guide and improve hydrogen production efficiency.In this thesis,based on the experimental research on hydrogen production from microwave liquid phase discharge plasma ethanol reforming,the third electrode was designed to optimize hydrogen production from both physical and chemical aspects.The reaction kinetic model of liquid phase discharge was established,and the reaction pathway of hydrogen production was revealed.The hydrogen production from microwave liquid phase discharge plasma ethanol reforming was analyzed from both macroscopic and microscopic perspectives.The main research contents and conclusions of this thesis are as follows:（1）The characteristics of microwave liquid phase discharge plasma were studied.The morphology of liquid phase discharge plasma,the growth law of plasma,the motion law of bubbles during discharge,and the emission spectral characteristics of plasma region were investigated.It was found that the formation time of a single bubble was between 62-76 ms.In a single bubble cycle,the volume of the plasma luminescent region first increased and then decreased,and the maximum volume of the plasma luminescent region was about 2.15 cm3.When the ethanol volume fraction is 75%.the plasma gas temperature increases from 3603 K to 5207 K with increasing microwave input power.（2）Experimental study on hydrogen production from ethanol solution by microwave liquid phase discharge.The effects of discharge parameters such as microwave power and ethanol volume fraction on hydrogen efficiency of microwave liquid phase discharge plasma system were studied.Preliminary speculation of possible reaction pathways.The material balance and stability of ethanol reforming to hydrogen production by microwave liquid phase discharge plasma were evaluated,and the results showed that:Increasing microwave power can increase the gas production flow rate and reduce the concentration of gas by-products,but does not change the reaction path of ethanol reforming hydrogen production.The volume fraction of ethanol affects the reaction pathway of hydrogen production,and the addition of water can enhance?OH and inhibit the formation of carbon deposits and gas byproducts.When the molar ratio of ethanol to water was 1:1,the flow rate of hydrogen and energy yield of hydrogen were 12.98 NL/min and 0.52 m3/k Wh,respectively,and the total concentration of H2 was 62.0%.The hydrogen recovery rate after seven hours of discharge was 95.5%.（3）Experimental study on hydrogen production from ethanol solution by microwave liquid phase third electrode discharge.The effects of the third electrode on plasma morphology,plasma growth,motion of bubbles during discharge,gas products and active particles were investigated.The results showed that the use of the third electrode can change the discharge state of the plasma and significantly increase the volume of the plasma luminescence area.The third electrode plays the role of hindering the upward movement of the bubbles,increasing the residence time of ethanol vapor in the plasma region by 30.3%.The metal third electrode promotes the dehydrogenation of gas by-products,and the large specific surface area is conducive to improving the hydrogen production efficiency.The highest energy yield of hydrogen production was 0.70 Nm3/k Wh,which was 29.6%higher than that of the non-metallic.When the third electrode was combined with 80 ppi copper metal foam,the total gas flow rate,hydrogen flow rate,and energy yield of hydrogen were29.90 NL/min,17.69 NL/min and 0.71 Nm3/k Wh,respectively,which increased by 33.3%,36.3%and 36.5%compared with the none third electrode.（4）The reaction kinetic model was used to study the mechanism of hydrogen production by microwave liquid phase discharge plasma ethanol reforming.It was found that?OH,?H and?CH3 dominate the hydrogen production process of microwave liquid phase discharge plasma ethanol reforming.?OH in the reaction system mainly comes from the decomposition of H2O molecules,and H2 mainly comes from the dehydrogenation reaction of?CH2 and the recombination reaction of?H with?CH3,H2O,CH4.The addition of?OH can reduce the consumption of H2 by?C,which plays a crucial role in increasing hydrogen production.The formation of C2H2,C2H4 and C2H6 mainly comes from the mutual recombination reaction between?CH,?CH2,?CH3,?C2H3.?H plays an important role in the consumption of C2H2,C2H4 and C2H6,which can promote the dehydrogenation of hydrocarbons and help increase hydrogen production.The use of a third electrode can increase the water conversion rate,promote the transfer of?H from hydrocarbons to H2,and reduce the concentration of by-products. |
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