Experimental Study On Catalytic Synthesis Of Ammonia Assisted By Dielectric Barrier Discharge Plasma

In recent years,with the continuous expansion of application requirements,non-equilibrium discharge plasma has become a research hotspot in various engineering fields.As the most important means of ammonia synthesis,traditional industrial ammonia accounts for one percent of the total global energy consumption.The main reason for the low energy utilization rate of conventional industrial ammonia is that the activation energy required for the reaction is high,which affects the chemical reaction process and the synthesis of ammonia.In a non-equilibrium plasma nitrogen fixation system,plasma discharge plays a role in reducing the activation energy and accelerating the reaction rate,and the non-equilibrium plasma synthesis of ammonia can improve the harsh reaction conditions of traditional synthetic ammonia,making the reaction under milder conditions get on.The catalyst also has the effect of changing the synthetic ammonia reaction pathway and reducing the activation energy required for the reaction.Therefore,it is of great significance to achieve low temperature activity,low energy consumption,high yield and high selectivity in nitrogen fixation system by means of discharge and catalytic synergy.In this paper,two experiments are carried out for the synthesis of ammonia by nanosecond pulse discharge synthesis and nanosecond pulse discharge,and the main research contents and conclusions are as follows:Firstly,the nanosecond pulse dielectric barrier discharge synthesis ammonia was experimentally studied without adding a catalyst,and different electrical parameters such as pulse voltage,frequency and pulse width were investigated for plasma discharge characteristics and gas concentration.The essence of electrical parameter adjustment is the change in system energy input.At the same time,the effects of gas pressure,temperature,gas flow per unit time and nitrogen-hydrogen ratio on gas concentration were studied,and the effects of ammonia concentration on particle number density,gas residence time,electron collision reaction and chemical reaction rate were studied.analysis.The results show that different nitrogen to hydrogen ratios have a significant effect on the synthesis of ammonia.To some extent,the electrical parameters that characterize energy,as well as the pressure and temperature,contribute to the synthesis of ammonia.However,an increase in gas flow per unit time suppresses the generation of ammonia gas.Secondly,the experimental study on the synergistic synthesis of ammonia by plasma-catalyst(Al2O3,SiO2)was carried out.The experimental results before and after the addition of the catalyst were compared and analyzed.It was found that the activation energy required for the synthesis of ammonia can be effectively reduced by the synergistic effect of plasma-catalysis.Increase the reaction path of synthetic ammonia,accelerate the reaction rate,and increase the ammonia concentration by nearly 6 times.It is also found that different catalytic effects have a greater effect on the synthesis of ammonia,and the catalytic effect of SiO2 is stronger than that of Al2O3 synthesis.The reaction rate is accelerated,and the ammonia concentration is increased by nearly 6 times.It is also found that different catalytic effects have a great effect on the synthesis of ammonia,and the catalytic effect of SiO2 is stronger than that of Al2O3.The nanosecond pulse discharge has the advantages of short rising edge time and stable discharge.Further,compared with the results of nanosecond pulse excitation discharge and AC,RF and microwave discharge assisted ammonia synthesis,it is found that the energy efficiency of nanosecond pulse discharge in ammonia synthesis is higher than other discharge methods,and the main influencing factors affecting ammonia concentration are the deposition energy of the system and the choice of catalyst.