Modified ZSM-5 For The Characterization Of Volatile Components Of Pyrolysis Of Victory Brown Coal Under Nitrogen And Hydrogenation Atmosphere

With the increasing shortage of global fossil energy and the environmental problems brought about by the use of fossil energy,the emergence of these problems urgently requires China to comprehensively consider its national conditions and make adjustments in the energy structure.As a large country with coal ownership and consumption,lignite accounts for a large proportion in China’s coal resources and coal consumption structure.Therefore,the clean and efficient utilization of lignite has become particularly important.Coal pyrolysis is the key core to realize the graded utilization of low metamorphic coal such as lignite,but the traditional coal pyrolysis has low product quality and difficult post-processing and utilization.Therefore,in order to realize the rational utilization of coal resources more efficiently,the effects of different modified ZSM-5 molecular sieves on the pyrolysis process of Shengli lignite in nitrogen atmosphere and hydrogenation atmosphere were investigated by using the rapid pyrolysis experimental device of powder particle fluidized bed,and the regeneration of catalyst in fluidized bed was investigated.First,the metal modified ZSM-5 zeolite catalyst was prepared,a series of methods were selected to characterize the catalyst acidity and structure,etc.,and the results found that:the metal loading does not affect the framework structure of the catalyst much,but the acidity changes to some extent,and the pore structure decreases with the metal loading.After metal modification,the distribution and composition of products from the pyrolysis reaction of Shengli brown coal changed.Under nitrogen atmosphere,when the catalyst was added,it had no great effect on the half tar yield,but sacrificed the tar yield and increased the gas yield,after the metal loading,it further promoted the catalytic cleavage of tar,the tar yield was lower than before modification,and the generation of each component in the gas also increased somewhat.The total aromatics content in tar increased from 28.4%to63.7%under non catalytic conditions after simultaneous introduction of metallic Ni.Under hydrogenation atmosphere,the pyrolysis half char yield decreased compared to that under nitrogen atmosphere,the relative increases of tar and gas yields were consistent,the changes of tar and gas yields after metal loading were consistent with that under nitrogen atmosphere,the gas components increased compared to nitrogen,the fatty hydrocarbons and phenolics in pyrolysis tar decreased significantly compared to that under nitrogen,and the phenolics after loading Fe and Co decreased by 63.4%and 68.4%compared to that under nitrogen,respectively.Secondly,multistage pore molecular sieves were prepared by base treatment and used as the support to support metal to synthesize AT-Me/ZSM-5 catalysts,and the analysis concluded that the molecular sieves structure was not changed after base treatment,the morphology became rough,the acid amount was also somewhat enlarged,and the pore structure was improved.Under nitrogen and hydrogenation atmosphere,the mesopores decreased the mass transfer resistance and improved the mass transfer efficiency,the pyrolysates were all improved significantly compared with those before alkaline treatment,the contents of each component in the gas were increased,and the quality of tar was also improved obviously.In which the introduction of Zn increased the relative content of monocyclic aromatic hydrocarbons by 48.4%under hydrogen atmosphere.Finally,the deactivated AT-Zn/ZSM-5 molecular sieve catalyst in the previous chapter was purged at 550℃and 1.8 L/min（85%N₂ and 15%O₂）for 30 min to realize the regeneration of the catalyst.Through the characterization analysis,it was found that the regeneration did not destroy the skeleton structure,but the acid content of the molecular sieve decreased and the mesoporous increased to a certain extent.After the regenerated catalyst participates in the pyrolysis reaction,the tar yield increases compared with that before regeneration,the gas yield decreases relatively,the content of each component in the gas decreases,and the fatty hydrocarbons and phenolic compounds in the tar increase.