Study On Plasma Assisted Plasma Iron-based Catalyst For Reforming N-pentane To Prepare Oxygenates

The rapid development of the automotive industry has brought convenience to people’s lives,and its exhaust emissions have also brought great harm to people’s health.The emission of exhaust pollutants is mainly caused by insufficient combustion of fuels such as gasoline or diesel.Reforming the fuel using low-temperature plasma can produce cleaner oxygenates.The addition of oxygenates can make the fuel burn more fully,thereby reducing the emission of toxic gases.Previous studies have shown that low-temperature plasma assisted Fe catalyst partial oxidation reforming of fuel can improve the selectivity of oxygenates in the product compared to using plasma alone.However,its selectivity is still low,and changes in O₂ concentration in the reactant can affect product generation.Therefore,selecting an appropriate O₂ concentration for fuel reforming is of great significance for improving the selectivity of oxygenates.In addition,adding another metal element（such as Mn）to the Fe catalyst to prepare a binary catalyst can also solve the problem of low oxygenates.Based on the above analysis,this article conducted a study on the low-temperature plasma assisted Fe based catalyst reforming n-C₅H₁₂ using n-C₅H₁₂ as a gasoline simulator,exploring the optimal O₂ concentration and analyzing the effect of O₂ concentration on plasma and product generation.At the same time,we conducted a series of studies on plasma assisted Fe based binary catalysts at the optimal concentration,exploring highly active catalysts and proposing a method for regulating oxygenates,The specific research content and conclusions are as follows:（1）Study on the partial oxidation reforming of n-C₅H₁₂ by low temperature plasma in collaboration with Fe/Al₂O₃ and O₂ concentration.In this chapter,we obtain the highest selectivity of oxygenates in reforming by changing O₂ concentration,and analyze the influence of O₂ concentration on the results of plasma discharge and reforming by current voltage,Lissajous graph,discharge region temperature,discharge region image and data.As O₂ is a electronegative gas,it is more likely to adsorb electrons,so the increase of O₂ concentration increases the initial voltage U_on and breakdown voltage U_b in the plasma.The increase of O₂ concentration will lead to the increase of the reduced field intensity E/N,which is often used to describe the degree of electron dissociation.Therefore,the increase of E/N will lead to the increase of the conversion rate of n-C₅H₁₂ and the increase of the temperature in the discharge area.In addition,the increase of O₂ concentration leads to the decrease of discharge area,which is related to the decrease of effective capacitance C_d of dielectric barrier layer.In addition,we introduce the concept of the relative concentration of O₂,which can be regarded as the concentration ratio of O₂/n-C₅H₁₂.When filling Fe/Al₂O₃ catalyst,we find that when the ratio of O₂/n-C₅H₁₂increases from 0.25 to 1,the selectivity of oxygenates increases.When the ratio of O₂/n-C₅H₁₂（volume ratio）continues to increase from 1 to 4,the oxygenates shows a trend of first rising and then decreasing.The maximum value is found when the ratio of O₂/n-C₅H₁₂ is 2,which indicates partial oxidation at low O2concentration and deep oxidation at high O₂ concentration.In addition,when the O₂/n-C₅H₁₂ ratio increases from 0.25 to 4,the alcohol/aldehyde ratio in oxygenates decreases monotonically.This is because the partial oxidation of n-C₅H₁₂ first undergoes the dissociation of n-C₅H₁₂ into C_xH_y/C_5-xH_12-y free radicals.Then C_xH_y/C_5-xH_12-y radical and O atom generate alcohols,which are further dehydrogenated into aldehydes.Therefore,there are more alcohols in hydrocarbon fuel containing oxygen with low concentration O₂.With the increase of O₂ concentration,dehydrogenation reaction is intensified,so the content of aldehydes gradually increases.The change of O₂ concentration can change the distribution of the products,which provides us with an idea of regulating the products in the reforming of n-C₅H₁₂.（2）Study on the partial oxidation reforming of n-C₅H₁₂ by low temperature plasma in cooperation with x Fey Mn/Al₂O₃In order to further improve the selectivity of plasma co-oxidation reforming of oxygenates in n-C₅H₁₂ with Fe/Al₂O₃,we prepared x Fey Mn/Al₂O₃catalyst by adding Mn to Fe/Al₂O₃ catalyst.The activity of n-C₅H₁₂ in low temperature plasma mass is studied at the optimum concentration found in the previous section.With the decrease of Fe/Mn ratio in catalyst,the conversion rate of n-C₅H₁₂ decreases from 30.2%to 11.3%,and the selectivity of oxygenates increases first and then decreases.The 3Fe7Mn/Al₂O₃ catalyst showed the highest selectivity of hydrocarbon fuel with oxygen of 70%.At the same time,we found through NH3-TPD that with the change of Fe/Mn ratio in catalyst,the acid sites of catalyst first decreased and then increased with the decrease of Fe/Mn ratio,among which 3Fe7Mn/Al₂O₃ had the lowest number of acid sites.It can be seen that the variation trend of acid site with Fe/Mn ratio is opposite to that of oxygenates selectivity.Based on the above results,we propose that the acidic sites of catalysts can inhibit the generation of oxygenates.We also study the products generated on the catalyst surface by in-situ DRIFTS,and the results are consistent with the experimental results.In addition,we believe that the acid site of the catalyst can control the conversion of n-C₅H₁₂.This study provides a new idea for improving the selectivity of oxygenates and regulating it in partial oxidation reforming of fuel.