Experimental Study On CH₄/CO₂ Reforming By Non-equilibrium Plasma Aided By Catalyst

As all known,human began facing two major crises in the 21st century.First,the greenhouse effect,caused by the burning of large amounts of C02 from fossil fuel combustion,led to global warming,climate and environmental problems;Secondly,because of the growing and the unscientific use of the energy,the oil resources would be increasingly exhausted and the oil crisis brought about.CH4 and CO2 were the two main greenhouse gases and their emission reduction,separation,collection,storage,conversion and reuse had been extensively concerned.Reforming CH4 and CO2 to produce hydrocarbons and syngas had important strategic significance for alleviating the oil crisis and mitigating the greenhouse effect.CH4 and CO2 were almost difficult to react under normal conditions.Non-equilibrium plasma technology allowed the reaction proceeding under milder conditions.Using the non-equilibrium plasma and catalyst synergistically to reform CH4 and CO2 had become a research hotspot.However,there were few studies on the co-reforming of CH4 and CO2 by non-equilibrium plasma and catalyst using nanosecond pulse power.The main research contents and conclusions of this thesis were as follows:(1)The influence of pulse,the pulse frequency and the ratio of CH4 to CO2 on reforming CH4/CO2 when the non-equilibrium plasma was used alone were investigated by using the nanosecond pulse dielectric barrier discharge.Selectivity:alkane>olefin>alkyne,CO>C2>C3.The most selective one among the hydrocarbons was C2H6.As the nanosecond pulse power input energy increased(pulse voltage or pulse frequency increased),the conversion of CH4 and CO2 were gradually increasing,the conversion of CH4 was up to 28.3%,the conversion of CO2 was up to 21.4%,the yields of H2 and CO were gradually increased,the yield of H2 was up to 9,9%and the yield of CO was up to 11.7%.When the proportion of CH4 was larger,it was more favorable for the formation of hydrocarbons.When the proportion of CH4 was smaller,it was more beneficial to increase the conversion of CH4 and CO2 and it was more conducive to the formation of H2 and CO.(2)The effects of pulse voltage,pulse frequency,carrier type and carrier specific surface area on the reforming of CH4/CO2 by non-equilibrium plasma aided by Ni-based catalysts were investigated by using nanosecond pulse dielectric barrier discharge.The results showed that the synergistic effects of non-equilibrium plasma and catalyst could improve the conversion of CH4 and CO2,the selectivity of Hz and CO and the yield of major products,H2and CO.The selectivity of hydrocarbons had dropped dramatically,compared with the non-equilibrium plasma alone.As the pulse voltage and pulse frequency increased,the conversion of CH4 and CO2,the yields of major products,H2 and CO increased gradually.The conversion of CH4 was up to 73.6%,the conversion of CO2 was up to 64.3%,the yield of H2 was up to 51.8%and the yield of CO was up to 52.6%.The Ni-based catalyst had a remarkable effect on improving the selectivity of HZ and CO.The activity of the carrier were in the following order:SiO2>Υ-Al2O3>4A molecular sieve.Larger surface area had better catalyst activity.